diff --git a/.DS_Store b/.DS_Store new file mode 100644 index 0000000..c07c531 Binary files /dev/null and b/.DS_Store differ diff --git a/QUIC overview - Document Experimental.pdf b/QUIC overview - Document Experimental.pdf new file mode 100644 index 0000000..5b02261 Binary files /dev/null and b/QUIC overview - Document Experimental.pdf differ diff --git a/README.md b/README.md index fcf2240..a243014 100644 --- a/README.md +++ b/README.md @@ -1,3 +1,9 @@ # TER_QUIC_STRI2A -sources TER QUIC \ No newline at end of file +sources TER QUIC + + +#sujet +Dans l’optique d’améliorer les performances temporelles du trafic http tout en conservant et la fiabilité sous-jacente du transfert et les propriétés de sécurité, Google a conçu et puis déployé un nouveau protocole « Quick UDP Internet Connections(QUIC) » s’appuyant sur UDP. +Depuis 2016, en s’inspirant de ce protocole et de son acronyme, l’IETF a entamé un travail de normalisation d’un nouveau protocole de transport appelé QUIC. Dernièrement, au sein de l’IETF, le groupe de travail sur QUIC et celui sur la standardisation de http/3 ont même fusionné. +L’objectif de ce TER est d’étudier le protocole QUIC de l’IETF et de faire un état des lieux des travaux de standardisation, de recherche, d’implémentation dont il fait actuellement l’objet et de son déploiement. A partir des nombreuses implémentations déjà existantes, une expérimentation pourra être réalisée afin d’évaluer sur un scénario à définir les gains apportés par QUIC en comparaison aux approches classiques http/TLS/TCP. diff --git a/biblio.bib b/biblio.bib new file mode 100644 index 0000000..e93d848 --- /dev/null +++ b/biblio.bib @@ -0,0 +1,235 @@ +@techreport{I-D.ietf-quic-tls, + author = {Martin Thomson and Sean Turner}, + title = {Using {TLS} to {Secure} {QUIC}}, + howpublished = {Working Draft}, + type = {Internet-Draft}, + number = {draft-ietf-quic-tls-27}, + year = {2020}, + month = {February}, + institution = {Internet Engineering Task Force}, + url = {https://datatracker.ietf.org/doc/html/draft-ietf-quic-tls-27}, + pagetotal = 52, + note = {{Work} in Progress}, +} + +@techreport{I-D.ietf-quic-http, + author = {Mike Bishop}, + title = {Hypertext {Transfer} {Protocol} {Version} 3 {(HTTP/3)}}, + howpublished = {Working Draft}, + type = {Internet-Draft}, + number = {draft-ietf-quic-http-27}, + year = {2020}, + month = {February}, + institution = {Internet Engineering Task Force}, + url = {https://datatracker.ietf.org/doc/html/draft-ietf-quic-http-27}, + pagetotal = 61, + note = {{Work} in Progress}, +} + +@techreport{I-D.ietf-quic-invariants, + author = {Martin Thomson}, + title = {{Version-Independent} {Properties} of {QUIC}}, + howpublished = {Working Draft}, + type = {Internet-Draft}, + number = {draft-ietf-quic-invariants-07}, + year = {2019}, + month = {September}, + institution = {Internet Engineering Task Force}, + url = {https://datatracker.ietf.org/doc/html/draft-ietf-quic-invariants-07}, + pagetotal = 10, + note = {{Work} in Progress}, +} + +@techreport{I-D.ietf-quic-qpack, + author = {Charles Krasic and Mike Bishop and Alan Frindell}, + title = {{QPACK}: {Header} {Compression} for {HTTP/3}}, + howpublished = {Working Draft}, + type = {Internet-Draft}, + number = {draft-ietf-quic-qpack-14}, + year = {2020}, + month = {February}, + institution = {Internet Engineering Task Force}, + url = {https://datatracker.ietf.org/doc/html/draft-ietf-quic-qpack-14}, + pagetotal = 38, + note = {{Work} in Progress}, +} + + +@techreport{I-D.ietf-quic-recovery, + author = {Jana Iyengar and Ian Swett}, + title = {{QUIC} {Loss} {Detection} and {Congestion} {Control}}, + howpublished = {Working Draft}, + type = {Internet-Draft}, + number = {draft-ietf-quic-recovery-26}, + year = {2020}, + month = {February}, + institution = {Internet Engineering Task Force}, + url = {https://datatracker.ietf.org/doc/html/draft-ietf-quic-recovery-26}, + pagetotal = 41, + note = {{Work} in Progress}, +} + +@techreport{I-D.ietf-quic-transport, + author = {Jana Iyengar and Martin Thomson}, + title = {{QUIC}: A {UDP-Based} {Multiplexed} and {Secure} {Transport}}, + howpublished = {Working Draft}, + type = {Internet-Draft}, + number = {draft-ietf-quic-transport-27}, + year = {2020}, + month = {February}, + institution = {Internet Engineering Task Force}, + url = {https://datatracker.ietf.org/doc/html/draft-ietf-quic-transport-27}, + pagetotal = 174, + note = {{Work} in Progress}, +} + +@ARTICLE{innovating-transport-with-quic-Cui-2017, +author={Y. {Cui} and T. {Li} and C. {Liu} and X. {Wang} and M. {Kühlewind}}, +journal={IEEE Internet Computing}, +title={Innovating {Transport} with {QUIC}: Design {Approaches} and {Research} {Challenges}}, +year={2017}, +volume={21}, +number={2}, +pages={72-76}, +keywords={Internet;transport protocols;quick UDP Internet connections;QUIC;transport protocol;Servers;Cryptography;Protocols;Data transfer;Packet loss;Internet and Web services;Multiplexing;Latency;Internet/Web technologies;IETF;QUIC;HTTP/2;TCP;TLS;Internet standards;latency;security and privacy;multiplexing}, +doi={10.1109/MIC.2017.44}, +ISSN={1941-0131}, +month={Mars},} + +@techreport{RFC0793, + author = {Jon Postel}, + title = {Transmission {Control} {Protocol}}, + howpublished = {Internet Requests for Comments}, + type = {STD}, + number = {7}, + year = {1981}, + month = {September}, + issn = {2070-1721}, + publisher = {RFC Editor}, + institution = {RFC Editor}, + url = {https://www.rfc-editor.org/rfc/rfc793}, +} + +@misc{quic-wg.implementations, + author = {{IETF QUIC Working Group}}, + title = {Implementations}, + year = 2020, + url = {https://github.com/quicwg/base-drafts/wiki/Implementations}, +} + +@misc{quic-wg.related-activities, + author = {{IETF QUIC Working Group}}, + title = {Related {Activities}}, + year = 2020, + url = {https://github.com/quicwg/base-drafts/wiki/Related-Activities}, +} + +@misc{quic-wg.tools, + author = {{IETF QUIC Working Group}}, + title = {Tools}, + year = 2020, + url = {https://github.com/quicwg/base-drafts/wiki/Tools}, +} + +@misc{quiche.impl, +author = {{Cloudflare}}, +title = {Quiche}, +year = 2020, +url = {https://github.com/cloudflare/quiche}, +} + +@misc{picoquic.impl, +author={{picoQUIC}}, +title= {{picoQUIC}}, +year = 2020, +url = {https://github.com/private-octopus/picoquic}, +} + +@misc{quant.impl, +author = {{NetApp}}, +title={quant}, +year = 2020, +url = {https://github.com/NTAP/quant}, +} + +@misc{ngtcp2.impl, +author={{ngtcp2}}, +title={{ngtcp2}}, +year = 2020, +url = { https://github.com/ngtcp2/ngtcp2}, +} + +@misc{nginx.impl, +author={{Cloudflare}}, +title={Quiche's nginx patch}, +year=2020, +url = {https://github.com/cloudflare/quiche/tree/master/extras/nginx}, +} + +@misc{curl.http3.experimental, +author={Daniel Stenberg}, +title={Curl's {HTTP3} experimental support}, +year=2020, +url={https://github.com/curl/curl/wiki/HTTP3}, +} + +@misc{curl.http3.installation, +author={Daniel Stenberg}, +title={{Curl's {HTTP3} (and {QUIC}) support}}, +year=2020, +url={https://github.com/curl/curl/blob/faaa63f32359c5e7e91c02ad421105b3e2079d15/docs/HTTP3.md}, +} + +@misc{neqo.impl, +author={Mozilla}, +title={Neqo, an {Implementation} of {QUIC} written in {Rust}}, +year=2020, +url={https://github.com/mozilla/neqo}, +} +@inproceedings{1902.06121, +Author = {Alvise {De Biasio} and Federico Chiariotti and Michele Polese and Andrea Zanella and Michele Zorzi}, +isbn = {9781450371407}, +publisher = {Association for Computing Machinery}, +address = {New York, NY, USA}, +doi = {10.1145/3321349.3321351}, +booktitle = {Proceedings of the 2019 Workshop on ns-3}, +pages = {1–8}, +numpages = {8}, +keywords = {transport protocols, ns-3, QUIC}, +location = {Florence, Italy}, +series = {WNS3 2019}, +Title = {A QUIC Implementation for ns-3}, +Year = {2019}, +Month ={June}, +} + +@techreport{deconinck-quic-multipath-03, + number = {draft-deconinck-quic-multipath-03}, + type = {Internet-Draft}, + institution = {Internet Engineering Task Force}, + publisher = {Internet Engineering Task Force}, + note = {{Work} in Progress}, + url = {https://datatracker.ietf.org/doc/html/draft-deconinck-quic-multipath-03}, + author = {Quentin {De Coninck} and Olivier Bonaventure}, + title = {{Multipath Extensions for QUIC (MP-QUIC)}}, + pagetotal = 32, + year = 2019, + month = {August}, + day = 29, + abstract = {This document specifies extensions to the QUIC protocol to enable, other than connection migration, simultaneous usage of multiple paths for a single connection. Those extensions remain compliant with the current single-path QUIC design. They allow devices to benefit from multiple network paths while preserving the privacy features of QUIC.}, +} +@techreport{pardue-quic-http-mcast-06, + number = {draft-pardue-quic-http-mcast-06}, + type = {Internet-Draft}, + institution = {Internet Engineering Task Force}, + publisher = {Internet Engineering Task Force}, + note = {{Work} in Progress}, + url = {https://datatracker.ietf.org/doc/html/draft-pardue-quic-http-mcast-06}, + author = {Lucas Pardue and Richard Bradbury and Sam Hurst}, + title = {{Hypertext Transfer Protocol (HTTP) over multicast QUIC}}, + pagetotal = 64, + year = 2020, + month = {February}, + day = 7, + abstract = {This document specifies a profile of the QUIC protocol and the HTTP/3 mapping that facilitates the transfer of HTTP resources over multicast IP using the QUIC transport as its framing and packetisation layer. Compatibility with the QUIC protocol's syntax and semantics is maintained as far as practical and additional features are specified where this is not possible.}, +} \ No newline at end of file diff --git a/images/0RTThandshake.pdf b/images/0RTThandshake.pdf new file mode 100644 index 0000000..88c634b Binary files /dev/null and b/images/0RTThandshake.pdf differ diff --git a/images/1RTThandshake.pdf b/images/1RTThandshake.pdf new file mode 100644 index 0000000..3f6e122 Binary files /dev/null and b/images/1RTThandshake.pdf differ diff --git a/images/QUIC-and-TLS-Interactions.pdf b/images/QUIC-and-TLS-Interactions.pdf new file mode 100644 index 0000000..e8a4a00 Binary files /dev/null and b/images/QUIC-and-TLS-Interactions.pdf differ diff --git a/images/TCP.pdf b/images/TCP.pdf new file mode 100644 index 0000000..1d2b449 Binary files /dev/null and b/images/TCP.pdf differ diff --git a/images/stri_logo.png b/images/stri_logo.png new file mode 100644 index 0000000..de5030b Binary files /dev/null and b/images/stri_logo.png differ diff --git a/llncs.cls b/llncs.cls new file mode 100644 index 0000000..886bf72 --- /dev/null +++ b/llncs.cls @@ -0,0 +1,1218 @@ +% LLNCS DOCUMENT CLASS -- version 2.20 (10-Mar-2018) +% Springer Verlag LaTeX2e support for Lecture Notes in Computer Science +% +%% +%% \CharacterTable +%% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z +%% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z +%% Digits \0\1\2\3\4\5\6\7\8\9 +%% Exclamation \! Double quote \" Hash (number) \# +%% Dollar \$ Percent \% Ampersand \& +%% Acute accent \' Left paren \( Right paren \) +%% Asterisk \* Plus \+ Comma \, +%% Minus \- Point \. Solidus \/ +%% Colon \: Semicolon \; Less than \< +%% Equals \= Greater than \> Question mark \? +%% Commercial at \@ Left bracket \[ Backslash \\ +%% Right bracket \] Circumflex \^ Underscore \_ +%% Grave accent \` Left brace \{ Vertical bar \| +%% Right brace \} Tilde \~} +%% +\NeedsTeXFormat{LaTeX2e}[1995/12/01] +\ProvidesClass{llncs}[2018/03/10 v2.20 +^^J LaTeX document class for Lecture Notes in Computer Science] +% Options +\let\if@envcntreset\iffalse +\DeclareOption{envcountreset}{\let\if@envcntreset\iftrue} +\DeclareOption{citeauthoryear}{\let\citeauthoryear=Y} +\DeclareOption{oribibl}{\let\oribibl=Y} +\let\if@custvec\iftrue +\DeclareOption{orivec}{\let\if@custvec\iffalse} +\let\if@envcntsame\iffalse +\DeclareOption{envcountsame}{\let\if@envcntsame\iftrue} +\let\if@envcntsect\iffalse +\DeclareOption{envcountsect}{\let\if@envcntsect\iftrue} +\let\if@runhead\iffalse +\DeclareOption{runningheads}{\let\if@runhead\iftrue} + +\let\if@openright\iftrue +\let\if@openbib\iffalse +\DeclareOption{openbib}{\let\if@openbib\iftrue} + +% languages +\let\switcht@@therlang\relax +\def\ds@deutsch{\def\switcht@@therlang{\switcht@deutsch}} +\def\ds@francais{\def\switcht@@therlang{\switcht@francais}} + +\DeclareOption*{\PassOptionsToClass{\CurrentOption}{article}} + +\ProcessOptions + +\LoadClass[twoside]{article} +\RequirePackage{multicol} % needed for the list of participants, index +\RequirePackage{aliascnt} + +\setlength{\textwidth}{12.2cm} +\setlength{\textheight}{19.3cm} +\renewcommand\@pnumwidth{2em} +\renewcommand\@tocrmarg{3.5em} +% +\def\@dottedtocline#1#2#3#4#5{% + \ifnum #1>\c@tocdepth \else + \vskip \z@ \@plus.2\p@ + {\leftskip #2\relax \rightskip \@tocrmarg \advance\rightskip by 0pt plus 2cm + \parfillskip -\rightskip \pretolerance=10000 + \parindent #2\relax\@afterindenttrue + \interlinepenalty\@M + \leavevmode + \@tempdima #3\relax + \advance\leftskip \@tempdima \null\nobreak\hskip -\leftskip + {#4}\nobreak + \leaders\hbox{$\m@th + \mkern \@dotsep mu\hbox{.}\mkern \@dotsep + mu$}\hfill + \nobreak + \hb@xt@\@pnumwidth{\hfil\normalfont \normalcolor #5}% + \par}% + \fi} +% +\def\switcht@albion{% +\def\abstractname{Abstract.} +\def\ackname{Acknowledgement.} +\def\andname{and} +\def\lastandname{\unskip, and} +\def\appendixname{Appendix} +\def\chaptername{Chapter} +\def\claimname{Claim} +\def\conjecturename{Conjecture} +\def\contentsname{Table of Contents} +\def\corollaryname{Corollary} +\def\definitionname{Definition} +\def\examplename{Example} +\def\exercisename{Exercise} +\def\figurename{Fig.} +\def\keywordname{{\bf Keywords:}} +\def\indexname{Index} +\def\lemmaname{Lemma} +\def\contriblistname{List of Contributors} +\def\listfigurename{List of Figures} +\def\listtablename{List of Tables} +\def\mailname{{\it Correspondence to\/}:} +\def\noteaddname{Note added in proof} +\def\notename{Note} +\def\partname{Part} +\def\problemname{Problem} +\def\proofname{Proof} +\def\propertyname{Property} +\def\propositionname{Proposition} +\def\questionname{Question} +\def\remarkname{Remark} +\def\seename{see} +\def\solutionname{Solution} +\def\subclassname{{\it Subject Classifications\/}:} +\def\tablename{Table} +\def\theoremname{Theorem}} +\switcht@albion +% Names of theorem like environments are already defined +% but must be translated if another language is chosen +% +% French section +\def\switcht@francais{%\typeout{On parle francais.}% + \def\abstractname{R\'esum\'e.}% + \def\ackname{Remerciements.}% + \def\andname{et}% + \def\lastandname{ et}% + \def\appendixname{Appendice} + \def\chaptername{Chapitre}% + \def\claimname{Pr\'etention}% + \def\conjecturename{Hypoth\`ese}% + \def\contentsname{Table des mati\`eres}% + \def\corollaryname{Corollaire}% + \def\definitionname{D\'efinition}% + \def\examplename{Exemple}% + \def\exercisename{Exercice}% + \def\figurename{Fig.}% + \def\keywordname{{\bf Mots-cl\'e:}} + \def\indexname{Index} + \def\lemmaname{Lemme}% + \def\contriblistname{Liste des contributeurs} + \def\listfigurename{Liste des figures}% + \def\listtablename{Liste des tables}% + \def\mailname{{\it Correspondence to\/}:} + \def\noteaddname{Note ajout\'ee \`a l'\'epreuve}% + \def\notename{Remarque}% + \def\partname{Partie}% + \def\problemname{Probl\`eme}% + \def\proofname{Preuve}% + \def\propertyname{Caract\'eristique}% +%\def\propositionname{Proposition}% + \def\questionname{Question}% + \def\remarkname{Remarque}% + \def\seename{voir} + \def\solutionname{Solution}% + \def\subclassname{{\it Subject Classifications\/}:} + \def\tablename{Tableau}% + \def\theoremname{Th\'eor\`eme}% +} +% +% German section +\def\switcht@deutsch{%\typeout{Man spricht deutsch.}% + \def\abstractname{Zusammenfassung.}% + \def\ackname{Danksagung.}% + \def\andname{und}% + \def\lastandname{ und}% + \def\appendixname{Anhang}% + \def\chaptername{Kapitel}% + \def\claimname{Behauptung}% + \def\conjecturename{Hypothese}% + \def\contentsname{Inhaltsverzeichnis}% + \def\corollaryname{Korollar}% +%\def\definitionname{Definition}% + \def\examplename{Beispiel}% + \def\exercisename{\"Ubung}% + \def\figurename{Abb.}% + \def\keywordname{{\bf Schl\"usselw\"orter:}} + \def\indexname{Index} +%\def\lemmaname{Lemma}% + \def\contriblistname{Mitarbeiter} + \def\listfigurename{Abbildungsverzeichnis}% + \def\listtablename{Tabellenverzeichnis}% + \def\mailname{{\it Correspondence to\/}:} + \def\noteaddname{Nachtrag}% + \def\notename{Anmerkung}% + \def\partname{Teil}% +%\def\problemname{Problem}% + \def\proofname{Beweis}% + \def\propertyname{Eigenschaft}% +%\def\propositionname{Proposition}% + \def\questionname{Frage}% + \def\remarkname{Anmerkung}% + \def\seename{siehe} + \def\solutionname{L\"osung}% + \def\subclassname{{\it Subject Classifications\/}:} + \def\tablename{Tabelle}% +%\def\theoremname{Theorem}% +} + +% Ragged bottom for the actual page +\def\thisbottomragged{\def\@textbottom{\vskip\z@ plus.0001fil +\global\let\@textbottom\relax}} + +\renewcommand\small{% + \@setfontsize\small\@ixpt{11}% + \abovedisplayskip 8.5\p@ \@plus3\p@ \@minus4\p@ + \abovedisplayshortskip \z@ \@plus2\p@ + \belowdisplayshortskip 4\p@ \@plus2\p@ \@minus2\p@ + \def\@listi{\leftmargin\leftmargini + \parsep 0\p@ \@plus1\p@ \@minus\p@ + \topsep 8\p@ \@plus2\p@ \@minus4\p@ + \itemsep0\p@}% + \belowdisplayskip \abovedisplayskip +} + +\frenchspacing +\widowpenalty=10000 +\clubpenalty=10000 + +\setlength\oddsidemargin {63\p@} +\setlength\evensidemargin {63\p@} +\setlength\marginparwidth {90\p@} + +\setlength\headsep {16\p@} + +\setlength\footnotesep{7.7\p@} +\setlength\textfloatsep{8mm\@plus 2\p@ \@minus 4\p@} +\setlength\intextsep {8mm\@plus 2\p@ \@minus 2\p@} + +\setcounter{secnumdepth}{2} + +\newcounter {chapter} +\renewcommand\thechapter {\@arabic\c@chapter} + +\newif\if@mainmatter \@mainmattertrue +\newcommand\frontmatter{\cleardoublepage + \@mainmatterfalse\pagenumbering{Roman}} +\newcommand\mainmatter{\cleardoublepage + \@mainmattertrue\pagenumbering{arabic}} +\newcommand\backmatter{\if@openright\cleardoublepage\else\clearpage\fi + \@mainmatterfalse} + +\renewcommand\part{\cleardoublepage + \thispagestyle{empty}% + \if@twocolumn + \onecolumn + \@tempswatrue + \else + \@tempswafalse + \fi + \null\vfil + \secdef\@part\@spart} + +\def\@part[#1]#2{% + \ifnum \c@secnumdepth >-2\relax + \refstepcounter{part}% + \addcontentsline{toc}{part}{\thepart\hspace{1em}#1}% + \else + \addcontentsline{toc}{part}{#1}% + \fi + \markboth{}{}% + {\centering + \interlinepenalty \@M + \normalfont + \ifnum \c@secnumdepth >-2\relax + \huge\bfseries \partname~\thepart + \par + \vskip 20\p@ + \fi + \Huge \bfseries #2\par}% + \@endpart} +\def\@spart#1{% + {\centering + \interlinepenalty \@M + \normalfont + \Huge \bfseries #1\par}% + \@endpart} +\def\@endpart{\vfil\newpage + \if@twoside + \null + \thispagestyle{empty}% + \newpage + \fi + \if@tempswa + \twocolumn + \fi} + +\newcommand\chapter{\clearpage + \thispagestyle{empty}% + \global\@topnum\z@ + \@afterindentfalse + \secdef\@chapter\@schapter} +\def\@chapter[#1]#2{\ifnum \c@secnumdepth >\m@ne + \if@mainmatter + \refstepcounter{chapter}% + \typeout{\@chapapp\space\thechapter.}% + \addcontentsline{toc}{chapter}% + {\protect\numberline{\thechapter}#1}% + \else + \addcontentsline{toc}{chapter}{#1}% + \fi + \else + \addcontentsline{toc}{chapter}{#1}% + \fi + \chaptermark{#1}% + \addtocontents{lof}{\protect\addvspace{10\p@}}% + \addtocontents{lot}{\protect\addvspace{10\p@}}% + \if@twocolumn + \@topnewpage[\@makechapterhead{#2}]% + \else + \@makechapterhead{#2}% + \@afterheading + \fi} +\def\@makechapterhead#1{% +% \vspace*{50\p@}% + {\centering + \ifnum \c@secnumdepth >\m@ne + \if@mainmatter + \large\bfseries \@chapapp{} \thechapter + \par\nobreak + \vskip 20\p@ + \fi + \fi + \interlinepenalty\@M + \Large \bfseries #1\par\nobreak + \vskip 40\p@ + }} +\def\@schapter#1{\if@twocolumn + \@topnewpage[\@makeschapterhead{#1}]% + \else + \@makeschapterhead{#1}% + \@afterheading + \fi} 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+\renewcommand\subparagraph[1]{\typeout{LLNCS warning: You should not use + \string\subparagraph\space with this class}\vskip0.5cm +You should not use \verb|\subparagraph| with this class.\vskip0.5cm} + +\DeclareMathSymbol{\Gamma}{\mathalpha}{letters}{"00} +\DeclareMathSymbol{\Delta}{\mathalpha}{letters}{"01} +\DeclareMathSymbol{\Theta}{\mathalpha}{letters}{"02} +\DeclareMathSymbol{\Lambda}{\mathalpha}{letters}{"03} +\DeclareMathSymbol{\Xi}{\mathalpha}{letters}{"04} +\DeclareMathSymbol{\Pi}{\mathalpha}{letters}{"05} +\DeclareMathSymbol{\Sigma}{\mathalpha}{letters}{"06} +\DeclareMathSymbol{\Upsilon}{\mathalpha}{letters}{"07} +\DeclareMathSymbol{\Phi}{\mathalpha}{letters}{"08} +\DeclareMathSymbol{\Psi}{\mathalpha}{letters}{"09} +\DeclareMathSymbol{\Omega}{\mathalpha}{letters}{"0A} + +\let\footnotesize\small + +\if@custvec +\def\vec#1{\mathchoice{\mbox{\boldmath$\displaystyle#1$}} +{\mbox{\boldmath$\textstyle#1$}} +{\mbox{\boldmath$\scriptstyle#1$}} +{\mbox{\boldmath$\scriptscriptstyle#1$}}} +\fi + +\def\squareforqed{\hbox{\rlap{$\sqcap$}$\sqcup$}} +\def\qed{\ifmmode\squareforqed\else{\unskip\nobreak\hfil +\penalty50\hskip1em\null\nobreak\hfil\squareforqed +\parfillskip=0pt\finalhyphendemerits=0\endgraf}\fi} + +\def\getsto{\mathrel{\mathchoice {\vcenter{\offinterlineskip +\halign{\hfil +$\displaystyle##$\hfil\cr\gets\cr\to\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr\gets +\cr\to\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr\gets +\cr\to\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr +\gets\cr\to\cr}}}}} +\def\lid{\mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil +$\displaystyle##$\hfil\cr<\cr\noalign{\vskip1.2pt}=\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr<\cr +\noalign{\vskip1.2pt}=\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr<\cr +\noalign{\vskip1pt}=\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr +<\cr +\noalign{\vskip0.9pt}=\cr}}}}} +\def\gid{\mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil +$\displaystyle##$\hfil\cr>\cr\noalign{\vskip1.2pt}=\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr>\cr +\noalign{\vskip1.2pt}=\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr>\cr +\noalign{\vskip1pt}=\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr +>\cr +\noalign{\vskip0.9pt}=\cr}}}}} +\def\grole{\mathrel{\mathchoice {\vcenter{\offinterlineskip +\halign{\hfil +$\displaystyle##$\hfil\cr>\cr\noalign{\vskip-1pt}<\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr +>\cr\noalign{\vskip-1pt}<\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr +>\cr\noalign{\vskip-0.8pt}<\cr}}} +{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr +>\cr\noalign{\vskip-0.3pt}<\cr}}}}} +\def\bbbr{{\rm I\!R}} %reelle Zahlen +\def\bbbm{{\rm I\!M}} +\def\bbbn{{\rm I\!N}} %natuerliche Zahlen +\def\bbbf{{\rm I\!F}} +\def\bbbh{{\rm I\!H}} +\def\bbbk{{\rm I\!K}} +\def\bbbp{{\rm I\!P}} +\def\bbbone{{\mathchoice {\rm 1\mskip-4mu l} {\rm 1\mskip-4mu l} +{\rm 1\mskip-4.5mu l} {\rm 1\mskip-5mu l}}} +\def\bbbc{{\mathchoice {\setbox0=\hbox{$\displaystyle\rm C$}\hbox{\hbox +to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}} +{\setbox0=\hbox{$\textstyle\rm C$}\hbox{\hbox +to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptstyle\rm C$}\hbox{\hbox +to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptscriptstyle\rm C$}\hbox{\hbox +to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}}}} +\def\bbbq{{\mathchoice {\setbox0=\hbox{$\displaystyle\rm +Q$}\hbox{\raise +0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.8\ht0\hss}\box0}} +{\setbox0=\hbox{$\textstyle\rm Q$}\hbox{\raise +0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.8\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptstyle\rm Q$}\hbox{\raise +0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.7\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptscriptstyle\rm Q$}\hbox{\raise +0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.7\ht0\hss}\box0}}}} +\def\bbbt{{\mathchoice {\setbox0=\hbox{$\displaystyle\rm +T$}\hbox{\hbox to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}} +{\setbox0=\hbox{$\textstyle\rm T$}\hbox{\hbox +to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptstyle\rm T$}\hbox{\hbox +to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptscriptstyle\rm T$}\hbox{\hbox +to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}}}} +\def\bbbs{{\mathchoice +{\setbox0=\hbox{$\displaystyle \rm S$}\hbox{\raise0.5\ht0\hbox +to0pt{\kern0.35\wd0\vrule height0.45\ht0\hss}\hbox +to0pt{\kern0.55\wd0\vrule height0.5\ht0\hss}\box0}} +{\setbox0=\hbox{$\textstyle \rm S$}\hbox{\raise0.5\ht0\hbox +to0pt{\kern0.35\wd0\vrule height0.45\ht0\hss}\hbox +to0pt{\kern0.55\wd0\vrule height0.5\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptstyle \rm S$}\hbox{\raise0.5\ht0\hbox +to0pt{\kern0.35\wd0\vrule height0.45\ht0\hss}\raise0.05\ht0\hbox +to0pt{\kern0.5\wd0\vrule height0.45\ht0\hss}\box0}} +{\setbox0=\hbox{$\scriptscriptstyle\rm S$}\hbox{\raise0.5\ht0\hbox +to0pt{\kern0.4\wd0\vrule height0.45\ht0\hss}\raise0.05\ht0\hbox +to0pt{\kern0.55\wd0\vrule height0.45\ht0\hss}\box0}}}} +\def\bbbz{{\mathchoice {\hbox{$\mathsf\textstyle Z\kern-0.4em Z$}} +{\hbox{$\mathsf\textstyle Z\kern-0.4em Z$}} +{\hbox{$\mathsf\scriptstyle Z\kern-0.3em Z$}} +{\hbox{$\mathsf\scriptscriptstyle Z\kern-0.2em Z$}}}} + +\let\ts\, + +\setlength\leftmargini {17\p@} +\setlength\leftmargin {\leftmargini} +\setlength\leftmarginii {\leftmargini} +\setlength\leftmarginiii {\leftmargini} +\setlength\leftmarginiv {\leftmargini} +\setlength \labelsep {.5em} +\setlength \labelwidth{\leftmargini} +\addtolength\labelwidth{-\labelsep} + +\def\@listI{\leftmargin\leftmargini + \parsep 0\p@ \@plus1\p@ \@minus\p@ + \topsep 8\p@ \@plus2\p@ \@minus4\p@ + \itemsep0\p@} +\let\@listi\@listI +\@listi +\def\@listii {\leftmargin\leftmarginii + \labelwidth\leftmarginii + \advance\labelwidth-\labelsep + \topsep 0\p@ \@plus2\p@ \@minus\p@} +\def\@listiii{\leftmargin\leftmarginiii + \labelwidth\leftmarginiii + \advance\labelwidth-\labelsep + \topsep 0\p@ \@plus\p@\@minus\p@ + \parsep \z@ + \partopsep \p@ \@plus\z@ \@minus\p@} + +\renewcommand\labelitemi{\normalfont\bfseries --} +\renewcommand\labelitemii{$\m@th\bullet$} + +\setlength\arraycolsep{1.4\p@} +\setlength\tabcolsep{1.4\p@} + +\def\tableofcontents{\chapter*{\contentsname\@mkboth{{\contentsname}}% + {{\contentsname}}} + \def\authcount##1{\setcounter{auco}{##1}\setcounter{@auth}{1}} + \def\lastand{\ifnum\value{auco}=2\relax + \unskip{} \andname\ + \else + \unskip \lastandname\ + \fi}% + \def\and{\stepcounter{@auth}\relax + \ifnum\value{@auth}=\value{auco}% + \lastand + \else + \unskip, + \fi}% + \@starttoc{toc}\if@restonecol\twocolumn\fi} + +\def\l@part#1#2{\addpenalty{\@secpenalty}% + \addvspace{2em plus\p@}% % space above part line + \begingroup + \parindent \z@ + \rightskip \z@ plus 5em + \hrule\vskip5pt + \large % same size as for a contribution heading + \bfseries\boldmath % set line in boldface + \leavevmode % TeX command to enter horizontal mode. + #1\par + \vskip5pt + \hrule + \vskip1pt + \nobreak % Never break after part entry + \endgroup} + +\def\@dotsep{2} + +\let\phantomsection=\relax + +\def\hyperhrefextend{\ifx\hyper@anchor\@undefined\else +{}\fi} + +\def\addnumcontentsmark#1#2#3{% +\addtocontents{#1}{\protect\contentsline{#2}{\protect\numberline + {\thechapter}#3}{\thepage}\hyperhrefextend}}% +\def\addcontentsmark#1#2#3{% +\addtocontents{#1}{\protect\contentsline{#2}{#3}{\thepage}\hyperhrefextend}}% +\def\addcontentsmarkwop#1#2#3{% +\addtocontents{#1}{\protect\contentsline{#2}{#3}{0}\hyperhrefextend}}% + +\def\@adcmk[#1]{\ifcase #1 \or +\def\@gtempa{\addnumcontentsmark}% + \or \def\@gtempa{\addcontentsmark}% + \or \def\@gtempa{\addcontentsmarkwop}% + \fi\@gtempa{toc}{chapter}% +} +\def\addtocmark{% +\phantomsection +\@ifnextchar[{\@adcmk}{\@adcmk[3]}% +} + +\def\l@chapter#1#2{\addpenalty{-\@highpenalty} + \vskip 1.0em plus 1pt \@tempdima 1.5em \begingroup + \parindent \z@ \rightskip \@tocrmarg + \advance\rightskip by 0pt plus 2cm + \parfillskip -\rightskip \pretolerance=10000 + \leavevmode \advance\leftskip\@tempdima \hskip -\leftskip + {\large\bfseries\boldmath#1}\ifx0#2\hfil\null + \else + \nobreak + \leaders\hbox{$\m@th \mkern \@dotsep mu.\mkern + \@dotsep mu$}\hfill + \nobreak\hbox to\@pnumwidth{\hss #2}% + \fi\par + \penalty\@highpenalty \endgroup} + +\def\l@title#1#2{\addpenalty{-\@highpenalty} + \addvspace{8pt plus 1pt} + \@tempdima \z@ + \begingroup + \parindent \z@ \rightskip \@tocrmarg + \advance\rightskip by 0pt plus 2cm + \parfillskip -\rightskip \pretolerance=10000 + \leavevmode \advance\leftskip\@tempdima \hskip -\leftskip + #1\nobreak + \leaders\hbox{$\m@th \mkern \@dotsep mu.\mkern + \@dotsep mu$}\hfill + \nobreak\hbox to\@pnumwidth{\hss #2}\par + \penalty\@highpenalty \endgroup} + +\def\l@author#1#2{\addpenalty{\@highpenalty} + \@tempdima=15\p@ %\z@ + \begingroup + \parindent \z@ \rightskip \@tocrmarg + \advance\rightskip by 0pt plus 2cm + \pretolerance=10000 + \leavevmode \advance\leftskip\@tempdima %\hskip -\leftskip + \textit{#1}\par + \penalty\@highpenalty \endgroup} + +\setcounter{tocdepth}{0} +\newdimen\tocchpnum +\newdimen\tocsecnum +\newdimen\tocsectotal +\newdimen\tocsubsecnum +\newdimen\tocsubsectotal +\newdimen\tocsubsubsecnum +\newdimen\tocsubsubsectotal +\newdimen\tocparanum +\newdimen\tocparatotal +\newdimen\tocsubparanum +\tocchpnum=\z@ % no chapter numbers +\tocsecnum=15\p@ % section 88. plus 2.222pt +\tocsubsecnum=23\p@ % subsection 88.8 plus 2.222pt +\tocsubsubsecnum=27\p@ % subsubsection 88.8.8 plus 1.444pt +\tocparanum=35\p@ % paragraph 88.8.8.8 plus 1.666pt +\tocsubparanum=43\p@ % subparagraph 88.8.8.8.8 plus 1.888pt +\def\calctocindent{% +\tocsectotal=\tocchpnum +\advance\tocsectotal by\tocsecnum +\tocsubsectotal=\tocsectotal +\advance\tocsubsectotal by\tocsubsecnum +\tocsubsubsectotal=\tocsubsectotal +\advance\tocsubsubsectotal by\tocsubsubsecnum +\tocparatotal=\tocsubsubsectotal +\advance\tocparatotal by\tocparanum} +\calctocindent + +\def\l@section{\@dottedtocline{1}{\tocchpnum}{\tocsecnum}} +\def\l@subsection{\@dottedtocline{2}{\tocsectotal}{\tocsubsecnum}} +\def\l@subsubsection{\@dottedtocline{3}{\tocsubsectotal}{\tocsubsubsecnum}} +\def\l@paragraph{\@dottedtocline{4}{\tocsubsubsectotal}{\tocparanum}} +\def\l@subparagraph{\@dottedtocline{5}{\tocparatotal}{\tocsubparanum}} + +\def\listoffigures{\@restonecolfalse\if@twocolumn\@restonecoltrue\onecolumn + \fi\section*{\listfigurename\@mkboth{{\listfigurename}}{{\listfigurename}}} + \@starttoc{lof}\if@restonecol\twocolumn\fi} +\def\l@figure{\@dottedtocline{1}{0em}{1.5em}} + +\def\listoftables{\@restonecolfalse\if@twocolumn\@restonecoltrue\onecolumn + \fi\section*{\listtablename\@mkboth{{\listtablename}}{{\listtablename}}} + \@starttoc{lot}\if@restonecol\twocolumn\fi} +\let\l@table\l@figure + +\renewcommand\listoffigures{% + \section*{\listfigurename + \@mkboth{\listfigurename}{\listfigurename}}% + \@starttoc{lof}% + } + +\renewcommand\listoftables{% + \section*{\listtablename + \@mkboth{\listtablename}{\listtablename}}% + \@starttoc{lot}% + } + +\ifx\oribibl\undefined +\ifx\citeauthoryear\undefined +\renewenvironment{thebibliography}[1] + {\section*{\refname} + \def\@biblabel##1{##1.} + \small + \list{\@biblabel{\@arabic\c@enumiv}}% + {\settowidth\labelwidth{\@biblabel{#1}}% + \leftmargin\labelwidth + \advance\leftmargin\labelsep + \if@openbib + \advance\leftmargin\bibindent + \itemindent -\bibindent + \listparindent \itemindent + \parsep \z@ + \fi + \usecounter{enumiv}% + \let\p@enumiv\@empty + \renewcommand\theenumiv{\@arabic\c@enumiv}}% + \if@openbib + \renewcommand\newblock{\par}% + \else + \renewcommand\newblock{\hskip .11em \@plus.33em \@minus.07em}% + \fi + \sloppy\clubpenalty4000\widowpenalty4000% + \sfcode`\.=\@m} + {\def\@noitemerr + {\@latex@warning{Empty `thebibliography' environment}}% + \endlist} +\def\@lbibitem[#1]#2{\item[{[#1]}\hfill]\if@filesw + {\let\protect\noexpand\immediate + \write\@auxout{\string\bibcite{#2}{#1}}}\fi\ignorespaces} +\newcount\@tempcntc +\def\@citex[#1]#2{\if@filesw\immediate\write\@auxout{\string\citation{#2}}\fi + \@tempcnta\z@\@tempcntb\m@ne\def\@citea{}\@cite{\@for\@citeb:=#2\do + {\@ifundefined + {b@\@citeb}{\@citeo\@tempcntb\m@ne\@citea\def\@citea{,}{\bfseries + ?}\@warning + {Citation `\@citeb' on page \thepage \space undefined}}% + {\setbox\z@\hbox{\global\@tempcntc0\csname b@\@citeb\endcsname\relax}% + \ifnum\@tempcntc=\z@ \@citeo\@tempcntb\m@ne + \@citea\def\@citea{,}\hbox{\csname b@\@citeb\endcsname}% + \else + \advance\@tempcntb\@ne + \ifnum\@tempcntb=\@tempcntc + \else\advance\@tempcntb\m@ne\@citeo + \@tempcnta\@tempcntc\@tempcntb\@tempcntc\fi\fi}}\@citeo}{#1}} +\def\@citeo{\ifnum\@tempcnta>\@tempcntb\else + \@citea\def\@citea{,\,\hskip\z@skip}% + \ifnum\@tempcnta=\@tempcntb\the\@tempcnta\else + {\advance\@tempcnta\@ne\ifnum\@tempcnta=\@tempcntb \else + \def\@citea{--}\fi + \advance\@tempcnta\m@ne\the\@tempcnta\@citea\the\@tempcntb}\fi\fi} +\else +\renewenvironment{thebibliography}[1] + {\section*{\refname} + \small + \list{}% + {\settowidth\labelwidth{}% + \leftmargin\parindent + \itemindent=-\parindent + \labelsep=\z@ + \if@openbib + \advance\leftmargin\bibindent + \itemindent -\bibindent + \listparindent \itemindent + \parsep \z@ + \fi + \usecounter{enumiv}% + \let\p@enumiv\@empty + \renewcommand\theenumiv{}}% + \if@openbib + \renewcommand\newblock{\par}% + \else + \renewcommand\newblock{\hskip .11em \@plus.33em \@minus.07em}% + \fi + \sloppy\clubpenalty4000\widowpenalty4000% + \sfcode`\.=\@m} + {\def\@noitemerr + {\@latex@warning{Empty `thebibliography' environment}}% + \endlist} + \def\@cite#1{#1}% + \def\@lbibitem[#1]#2{\item[]\if@filesw + {\def\protect##1{\string ##1\space}\immediate + \write\@auxout{\string\bibcite{#2}{#1}}}\fi\ignorespaces} + \fi +\else +\@cons\@openbib@code{\noexpand\small} +\fi + +\def\idxquad{\hskip 10\p@}% space that divides entry from number + +\def\@idxitem{\par\hangindent 10\p@} + +\def\subitem{\par\setbox0=\hbox{--\enspace}% second order + \noindent\hangindent\wd0\box0}% index entry + +\def\subsubitem{\par\setbox0=\hbox{--\,--\enspace}% third + \noindent\hangindent\wd0\box0}% order index entry + +\def\indexspace{\par \vskip 10\p@ plus5\p@ minus3\p@\relax} + +\renewenvironment{theindex} + {\@mkboth{\indexname}{\indexname}% + \thispagestyle{empty}\parindent\z@ + \parskip\z@ \@plus .3\p@\relax + \let\item\par + \def\,{\relax\ifmmode\mskip\thinmuskip + \else\hskip0.2em\ignorespaces\fi}% + \normalfont\small + \begin{multicols}{2}[\@makeschapterhead{\indexname}]% + } + {\end{multicols}} + +\renewcommand\footnoterule{% + \kern-3\p@ + \hrule\@width 2truecm + \kern2.6\p@} + \newdimen\fnindent + \fnindent1em +\long\def\@makefntext#1{% + \parindent \fnindent% + \leftskip \fnindent% + \noindent + \llap{\hb@xt@1em{\hss\@makefnmark\ }}\ignorespaces#1} + +\long\def\@makecaption#1#2{% + \small + \vskip\abovecaptionskip + \sbox\@tempboxa{{\bfseries #1.} #2}% + \ifdim \wd\@tempboxa >\hsize + {\bfseries #1.} #2\par + \else + \global \@minipagefalse + \hb@xt@\hsize{\hfil\box\@tempboxa\hfil}% + \fi + \vskip\belowcaptionskip} + +\def\fps@figure{htbp} +\def\fnum@figure{\figurename\thinspace\thefigure} +\def \@floatboxreset {% + \reset@font + \small + \@setnobreak + \@setminipage +} +\def\fps@table{htbp} +\def\fnum@table{\tablename~\thetable} +\renewenvironment{table} + {\setlength\abovecaptionskip{0\p@}% + \setlength\belowcaptionskip{10\p@}% + \@float{table}} + {\end@float} +\renewenvironment{table*} + {\setlength\abovecaptionskip{0\p@}% + \setlength\belowcaptionskip{10\p@}% + \@dblfloat{table}} + {\end@dblfloat} + +\long\def\@caption#1[#2]#3{\par\addcontentsline{\csname + ext@#1\endcsname}{#1}{\protect\numberline{\csname + the#1\endcsname}{\ignorespaces #2}}\begingroup + \@parboxrestore + \@makecaption{\csname fnum@#1\endcsname}{\ignorespaces #3}\par + \endgroup} + +% LaTeX does not provide a command to enter the authors institute +% addresses. The \institute command is defined here. + +\newcounter{@inst} +\newcounter{@auth} +\newcounter{auco} +\newdimen\instindent +\newbox\authrun +\newtoks\authorrunning +\newtoks\tocauthor +\newbox\titrun +\newtoks\titlerunning +\newtoks\toctitle + +\def\clearheadinfo{\gdef\@author{No Author Given}% + \gdef\@title{No Title Given}% + \gdef\@subtitle{}% + \gdef\@institute{No Institute Given}% + \gdef\@thanks{}% + \global\titlerunning={}\global\authorrunning={}% + \global\toctitle={}\global\tocauthor={}} + +\def\institute#1{\gdef\@institute{#1}} + +\def\institutename{\par + \begingroup + \parskip=\z@ + \parindent=\z@ + \setcounter{@inst}{1}% + \def\and{\par\stepcounter{@inst}% + \noindent$^{\the@inst}$\enspace\ignorespaces}% + \setbox0=\vbox{\def\thanks##1{}\@institute}% + \ifnum\c@@inst=1\relax + \gdef\fnnstart{0}% + \else + \xdef\fnnstart{\c@@inst}% + \setcounter{@inst}{1}% + \noindent$^{\the@inst}$\enspace + \fi + \ignorespaces + \@institute\par + \endgroup} + +\def\@fnsymbol#1{\ensuremath{\ifcase#1\or\star\or{\star\star}\or + {\star\star\star}\or \dagger\or \ddagger\or + \mathchar "278\or \mathchar "27B\or \|\or **\or \dagger\dagger + \or \ddagger\ddagger \else\@ctrerr\fi}} + +\def\inst#1{\unskip$^{#1}$} +\def\orcidID#1{\unskip$^{[#1]}$} % added MR 2018-03-10 +\def\fnmsep{\unskip$^,$} +\def\email#1{{\tt#1}} + +\AtBeginDocument{\@ifundefined{url}{\def\url#1{#1}}{}% +\@ifpackageloaded{babel}{% +\@ifundefined{extrasenglish}{}{\addto\extrasenglish{\switcht@albion}}% +\@ifundefined{extrasfrenchb}{}{\addto\extrasfrenchb{\switcht@francais}}% +\@ifundefined{extrasgerman}{}{\addto\extrasgerman{\switcht@deutsch}}% +\@ifundefined{extrasngerman}{}{\addto\extrasngerman{\switcht@deutsch}}% +}{\switcht@@therlang}% +\providecommand{\keywords}[1]{\def\and{{\textperiodcentered} }% +\par\addvspace\baselineskip +\noindent\keywordname\enspace\ignorespaces#1}% +\@ifpackageloaded{hyperref}{% +\def\doi#1{\href{https://doi.org/#1}{https://doi.org/#1}}}{ +\def\doi#1{https://doi.org/#1}} +} +\def\homedir{\~{ }} + +\def\subtitle#1{\gdef\@subtitle{#1}} +\clearheadinfo +% +%%% to avoid hyperref warnings +\providecommand*{\toclevel@author}{999} +%%% to make title-entry parent of section-entries +\providecommand*{\toclevel@title}{0} +% +\renewcommand\maketitle{\newpage +\phantomsection + \refstepcounter{chapter}% + \stepcounter{section}% + \setcounter{section}{0}% + \setcounter{subsection}{0}% + \setcounter{figure}{0} + \setcounter{table}{0} + \setcounter{equation}{0} + \setcounter{footnote}{0}% + \begingroup + \parindent=\z@ + \renewcommand\thefootnote{\@fnsymbol\c@footnote}% + \if@twocolumn + \ifnum \col@number=\@ne + \@maketitle + \else + \twocolumn[\@maketitle]% + \fi + \else + \newpage + \global\@topnum\z@ % Prevents figures from going at top of page. + \@maketitle + \fi + \thispagestyle{empty}\@thanks +% + \def\\{\unskip\ \ignorespaces}\def\inst##1{\unskip{}}% + \def\thanks##1{\unskip{}}\def\fnmsep{\unskip}% + \instindent=\hsize + \advance\instindent by-\headlineindent + \if!\the\toctitle!\addcontentsline{toc}{title}{\@title}\else + \addcontentsline{toc}{title}{\the\toctitle}\fi + \if@runhead + \if!\the\titlerunning!\else + \edef\@title{\the\titlerunning}% + \fi + \global\setbox\titrun=\hbox{\small\rm\unboldmath\ignorespaces\@title}% + \ifdim\wd\titrun>\instindent + \typeout{Title too long for running head. Please supply}% + \typeout{a shorter form with \string\titlerunning\space prior to + \string\maketitle}% + \global\setbox\titrun=\hbox{\small\rm + Title Suppressed Due to Excessive Length}% + \fi + \xdef\@title{\copy\titrun}% + \fi +% + \if!\the\tocauthor!\relax + {\def\and{\noexpand\protect\noexpand\and}% + \def\inst##1{}% added MR 2017-09-20 to remove inst numbers from the TOC + \def\orcidID##1{}% added MR 2017-09-20 to remove ORCID ids from the TOC + \protected@xdef\toc@uthor{\@author}}% + \else + \def\\{\noexpand\protect\noexpand\newline}% + \protected@xdef\scratch{\the\tocauthor}% + \protected@xdef\toc@uthor{\scratch}% + \fi + \addtocontents{toc}{\noexpand\protect\noexpand\authcount{\the\c@auco}}% + \addcontentsline{toc}{author}{\toc@uthor}% + \if@runhead + \if!\the\authorrunning! + \value{@inst}=\value{@auth}% + \setcounter{@auth}{1}% + \else + \edef\@author{\the\authorrunning}% + \fi + \global\setbox\authrun=\hbox{\def\inst##1{}% added MR 2017-09-20 to remove inst numbers from the runninghead + \def\orcidID##1{}% added MR 2017-09-20 to remove ORCID ids from the runninghead + \small\unboldmath\@author\unskip}% + \ifdim\wd\authrun>\instindent + \typeout{Names of authors too long for running head. Please supply}% + \typeout{a shorter form with \string\authorrunning\space prior to + \string\maketitle}% + \global\setbox\authrun=\hbox{\small\rm + Authors Suppressed Due to Excessive Length}% + \fi + \xdef\@author{\copy\authrun}% + \markboth{\@author}{\@title}% + \fi + \endgroup + \setcounter{footnote}{\fnnstart}% + \clearheadinfo} +% +\def\@maketitle{\newpage + \markboth{}{}% + \def\lastand{\ifnum\value{@inst}=2\relax + \unskip{} \andname\ + \else + \unskip \lastandname\ + \fi}% + \def\and{\stepcounter{@auth}\relax + \ifnum\value{@auth}=\value{@inst}% + \lastand + \else + \unskip, + \fi}% + \begin{center}% + \let\newline\\ + {\Large \bfseries\boldmath + \pretolerance=10000 + \@title \par}\vskip .8cm +\if!\@subtitle!\else {\large \bfseries\boldmath + \vskip -.65cm + \pretolerance=10000 + \@subtitle \par}\vskip .8cm\fi + \setbox0=\vbox{\setcounter{@auth}{1}\def\and{\stepcounter{@auth}}% + \def\thanks##1{}\@author}% + \global\value{@inst}=\value{@auth}% + \global\value{auco}=\value{@auth}% + \setcounter{@auth}{1}% +{\lineskip .5em +\noindent\ignorespaces +\@author\vskip.35cm} + {\small\institutename} + \end{center}% + } + +% definition of the "\spnewtheorem" command. +% +% Usage: +% +% \spnewtheorem{env_nam}{caption}[within]{cap_font}{body_font} +% or \spnewtheorem{env_nam}[numbered_like]{caption}{cap_font}{body_font} +% or \spnewtheorem*{env_nam}{caption}{cap_font}{body_font} +% +% New is "cap_font" and "body_font". It stands for +% fontdefinition of the caption and the text itself. +% +% "\spnewtheorem*" gives a theorem without number. +% +% A defined spnewthoerem environment is used as described +% by Lamport. +% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +\def\@thmcountersep{} +\def\@thmcounterend{.} + +\def\spnewtheorem{\@ifstar{\@sthm}{\@Sthm}} + +% definition of \spnewtheorem with number + +\def\@spnthm#1#2{% + \@ifnextchar[{\@spxnthm{#1}{#2}}{\@spynthm{#1}{#2}}} +\def\@Sthm#1{\@ifnextchar[{\@spothm{#1}}{\@spnthm{#1}}} + +\def\@spxnthm#1#2[#3]#4#5{\expandafter\@ifdefinable\csname #1\endcsname + {\@definecounter{#1}\@addtoreset{#1}{#3}% + \expandafter\xdef\csname the#1\endcsname{\expandafter\noexpand + \csname the#3\endcsname \noexpand\@thmcountersep \@thmcounter{#1}}% + \expandafter\xdef\csname #1name\endcsname{#2}% + \global\@namedef{#1}{\@spthm{#1}{\csname #1name\endcsname}{#4}{#5}}% + \global\@namedef{end#1}{\@endtheorem}}} + +\def\@spynthm#1#2#3#4{\expandafter\@ifdefinable\csname #1\endcsname + {\@definecounter{#1}% + \expandafter\xdef\csname the#1\endcsname{\@thmcounter{#1}}% + \expandafter\xdef\csname #1name\endcsname{#2}% + \global\@namedef{#1}{\@spthm{#1}{\csname #1name\endcsname}{#3}{#4}}% + \global\@namedef{end#1}{\@endtheorem}}} + +\def\@spothm#1[#2]#3#4#5{% + \@ifundefined{c@#2}{\@latexerr{No theorem environment `#2' defined}\@eha}% + {\expandafter\@ifdefinable\csname #1\endcsname + {\newaliascnt{#1}{#2}% + \expandafter\xdef\csname #1name\endcsname{#3}% + \global\@namedef{#1}{\@spthm{#1}{\csname #1name\endcsname}{#4}{#5}}% + \global\@namedef{end#1}{\@endtheorem}}}} + +\def\@spthm#1#2#3#4{\topsep 7\p@ \@plus2\p@ \@minus4\p@ +\refstepcounter{#1}% +\@ifnextchar[{\@spythm{#1}{#2}{#3}{#4}}{\@spxthm{#1}{#2}{#3}{#4}}} + +\def\@spxthm#1#2#3#4{\@spbegintheorem{#2}{\csname the#1\endcsname}{#3}{#4}% + \ignorespaces} + +\def\@spythm#1#2#3#4[#5]{\@spopargbegintheorem{#2}{\csname + the#1\endcsname}{#5}{#3}{#4}\ignorespaces} + +\def\@spbegintheorem#1#2#3#4{\trivlist + \item[\hskip\labelsep{#3#1\ #2\@thmcounterend}]#4} + +\def\@spopargbegintheorem#1#2#3#4#5{\trivlist + \item[\hskip\labelsep{#4#1\ #2}]{#4(#3)\@thmcounterend\ }#5} + +% definition of \spnewtheorem* without number + +\def\@sthm#1#2{\@Ynthm{#1}{#2}} + +\def\@Ynthm#1#2#3#4{\expandafter\@ifdefinable\csname #1\endcsname + {\global\@namedef{#1}{\@Thm{\csname #1name\endcsname}{#3}{#4}}% + \expandafter\xdef\csname #1name\endcsname{#2}% + \global\@namedef{end#1}{\@endtheorem}}} + +\def\@Thm#1#2#3{\topsep 7\p@ \@plus2\p@ \@minus4\p@ +\@ifnextchar[{\@Ythm{#1}{#2}{#3}}{\@Xthm{#1}{#2}{#3}}} + +\def\@Xthm#1#2#3{\@Begintheorem{#1}{#2}{#3}\ignorespaces} + +\def\@Ythm#1#2#3[#4]{\@Opargbegintheorem{#1} + {#4}{#2}{#3}\ignorespaces} + +\def\@Begintheorem#1#2#3{#3\trivlist + \item[\hskip\labelsep{#2#1\@thmcounterend}]} + +\def\@Opargbegintheorem#1#2#3#4{#4\trivlist + \item[\hskip\labelsep{#3#1}]{#3(#2)\@thmcounterend\ }} + +\if@envcntsect + \def\@thmcountersep{.} + \spnewtheorem{theorem}{Theorem}[section]{\bfseries}{\itshape} +\else + \spnewtheorem{theorem}{Theorem}{\bfseries}{\itshape} + \if@envcntreset + \@addtoreset{theorem}{section} + \else + \@addtoreset{theorem}{chapter} + \fi +\fi + +%definition of divers theorem environments +\spnewtheorem*{claim}{Claim}{\itshape}{\rmfamily} +\spnewtheorem*{proof}{Proof}{\itshape}{\rmfamily} +\if@envcntsame % alle Umgebungen wie Theorem. + \def\spn@wtheorem#1#2#3#4{\@spothm{#1}[theorem]{#2}{#3}{#4}} +\else % alle Umgebungen mit eigenem Zaehler + \if@envcntsect % mit section numeriert + \def\spn@wtheorem#1#2#3#4{\@spxnthm{#1}{#2}[section]{#3}{#4}} + \else % nicht mit section numeriert + \if@envcntreset + \def\spn@wtheorem#1#2#3#4{\@spynthm{#1}{#2}{#3}{#4} + \@addtoreset{#1}{section}} + \else + \def\spn@wtheorem#1#2#3#4{\@spynthm{#1}{#2}{#3}{#4} + \@addtoreset{#1}{chapter}}% + \fi + \fi +\fi +\spn@wtheorem{case}{Case}{\itshape}{\rmfamily} +\spn@wtheorem{conjecture}{Conjecture}{\itshape}{\rmfamily} +\spn@wtheorem{corollary}{Corollary}{\bfseries}{\itshape} +\spn@wtheorem{definition}{Definition}{\bfseries}{\itshape} +\spn@wtheorem{example}{Example}{\itshape}{\rmfamily} +\spn@wtheorem{exercise}{Exercise}{\itshape}{\rmfamily} +\spn@wtheorem{lemma}{Lemma}{\bfseries}{\itshape} +\spn@wtheorem{note}{Note}{\itshape}{\rmfamily} +\spn@wtheorem{problem}{Problem}{\itshape}{\rmfamily} +\spn@wtheorem{property}{Property}{\itshape}{\rmfamily} +\spn@wtheorem{proposition}{Proposition}{\bfseries}{\itshape} +\spn@wtheorem{question}{Question}{\itshape}{\rmfamily} +\spn@wtheorem{solution}{Solution}{\itshape}{\rmfamily} +\spn@wtheorem{remark}{Remark}{\itshape}{\rmfamily} + +\def\@takefromreset#1#2{% + \def\@tempa{#1}% + \let\@tempd\@elt + \def\@elt##1{% + \def\@tempb{##1}% + \ifx\@tempa\@tempb\else + \@addtoreset{##1}{#2}% + \fi}% + \expandafter\expandafter\let\expandafter\@tempc\csname cl@#2\endcsname + \expandafter\def\csname cl@#2\endcsname{}% + \@tempc + \let\@elt\@tempd} + +\def\theopargself{\def\@spopargbegintheorem##1##2##3##4##5{\trivlist + \item[\hskip\labelsep{##4##1\ ##2}]{##4##3\@thmcounterend\ }##5} + \def\@Opargbegintheorem##1##2##3##4{##4\trivlist + \item[\hskip\labelsep{##3##1}]{##3##2\@thmcounterend\ }} + } + +\renewenvironment{abstract}{% + \list{}{\advance\topsep by0.35cm\relax\small + \leftmargin=1cm + \labelwidth=\z@ + \listparindent=\z@ + \itemindent\listparindent + \rightmargin\leftmargin}\item[\hskip\labelsep + \bfseries\abstractname]} + {\endlist} + +\newdimen\headlineindent % dimension for space between +\headlineindent=1.166cm % number and text of headings. + +\def\ps@headings{\let\@mkboth\@gobbletwo + \let\@oddfoot\@empty\let\@evenfoot\@empty + \def\@evenhead{\normalfont\small\rlap{\thepage}\hspace{\headlineindent}% + \leftmark\hfil} + \def\@oddhead{\normalfont\small\hfil\rightmark\hspace{\headlineindent}% + \llap{\thepage}} + \def\chaptermark##1{}% + \def\sectionmark##1{}% + \def\subsectionmark##1{}} + +\def\ps@titlepage{\let\@mkboth\@gobbletwo + \let\@oddfoot\@empty\let\@evenfoot\@empty + \def\@evenhead{\normalfont\small\rlap{\thepage}\hspace{\headlineindent}% + \hfil} + \def\@oddhead{\normalfont\small\hfil\hspace{\headlineindent}% + \llap{\thepage}} + \def\chaptermark##1{}% + \def\sectionmark##1{}% + \def\subsectionmark##1{}} + +\if@runhead\ps@headings\else +\ps@empty\fi + +\setlength\arraycolsep{1.4\p@} +\setlength\tabcolsep{1.4\p@} + +\endinput +%end of file llncs.cls diff --git a/llncsdoc.pdf b/llncsdoc.pdf new file mode 100644 index 0000000..24a36b5 Binary files /dev/null and b/llncsdoc.pdf differ diff --git a/quic.tex b/quic.tex new file mode 100644 index 0000000..17d79f5 --- /dev/null +++ b/quic.tex @@ -0,0 +1,258 @@ +\documentclass[runningheads]{llncs} +\usepackage[english]{babel} +\usepackage{graphicx} +\usepackage{subcaption} +\usepackage{float} +\setlength\intextsep{0mm} +% Used for displaying a sample figure. If possible, figure files should be included in EPS format. +% If you use the hyperref package, please uncomment the following line to display URLs in blue roman font according to Springer's eBook style: +\usepackage[pdfencoding=auto,psdextra,bookmarks=false]{hyperref} +\renewcommand\UrlFont{\color{blue}\rmfamily} + % pour que les liens avec le doi soient aussi colorés en bleu comme demandé +\hypersetup{colorlinks=true,urlcolor=blue} +% Macros custom +\newcommand\ProtocolElement[1]{\texttt{#1}} + +\begin{document} + +\title{QUIC overview} +\author{Flavien Haas \and Louis Royer \and Daniel Sanchez Pelegrin\and Maïmouna Diouf \and Carine Koumsaga} +\institute{UPSSITECH, Paul Sabatier University campus in Toulouse, France} +\authorrunning{F. Haas, L. Royer, D. Sanchez, M. Diouf, C. Koumsaga} +% First names are abbreviated in the running head. If there are more than two authors, 'et al.' is used. +\maketitle + +\begin{abstract} +This paper explains the basic principle of QUIC protocol, located just above UDP, in its ways of standardization by the IETF. QUIC is going to be the transport protocol used in HTTP/3, this paper aims to describe how handshake and data transfer are orchestrated while comparing them to TCP HTTP/2. This approach allows explaining the need for QUIC and how it solves HTTP/2’s issues like the lack of early data management, TCP’s head-of-line blocking or higher number of RTT. Then, it shows an overview of QUIC’s next implementations with current research issues and a summary table of the comparison with TCP. +\keywords{OSI model \and Transport layer \and QUIC \and Internet Protocol} +\end{abstract} + +\section{Introduction} +The beginning of the 21st century has been marked with the use of the internet. For communicating, we used in first telephonic lines that have been made only for voice, and therefore haven't been reliable for data. Transport protocols like TCP \cite{rfc0793} were created to assure that information will be delivered. + +Many round trips are needed to verify that data are received correctly. +Now, the complexity of our usages makes the internet an expanding place. In times where connections multiply on a very large scale, these connections must be always faster; and protocol study is necessary to meet those requierements. + +QUIC is a new transport protocol developed by many companies. It aims to improve the internet efficiency. +For instance, Google and IETF are the main contributors in this project. Google has developed gQUIC, its own version of the protocol and uses it for its own services. +On the other hand, IETF's goal is to standardize the protocol to be used worldwide. + +QUIC introduces HTTP/3 \cite{I-D.ietf-quic-http}. +The goal is to solve problems related to HTTP/2 linked to the use of TCP: like minimizing the latency of the handshake, introducing early data and prevent TCP’s head-of-line blocking \cite{I-D.ietf-quic-qpack}. +In this document, we will discuss how IETF's QUIC solves these issues while explaining how it works. + +The rest of the paper is organized as follows. Section~\ref{section:crypto-based-handshake} describes Crypto-based Handshake. Data transfer is presented in section~\ref{section:data-transfer}. Section~\ref{section:research-issues} presents research issues. Section~\ref{section:general-analysis} summarize differences between TCP and QUIC. + +\section{Crypto-based Handshake}\label{section:crypto-based-handshake} +To minimize connection establishment latency, QUIC relies on a combined cryptographic and transport handshake. Each connection starts with a handshake phase in which one client and one server establish a shared secret \cite[section~5.3]{I-D.ietf-quic-transport}. + +\subsection{Handshake} +TLS provides two handshake mode to QUIC \cite[section~2.1]{I-D.ietf-quic-tls}: +\begin{description} + \item [A full 1-RTT handshake]: client is able to send Application Data after one round trip and the server can immediately respond. + \item [A 0-RTT handshake]: client uses information previously learned about the server and then is able to send Application Data immediately, but server can accept or reject early data sent with this handshake mode \cite[section~17.2.3]{I-D.ietf-quic-transport} (see section~\ref{section:0-RTT}). +\end{description} + +\begin{figure}[ht] + \centering + \begin{subfigure}[b]{0.49\linewidth} + \caption{0-RTT handshake \cite[Figure 4]{I-D.ietf-quic-transport}.} + \includegraphics[width=\linewidth]{images/0RTThandshake.pdf} + \label{fig:0RTThandshake} + \end{subfigure} + \begin{subfigure}[b]{0.49\linewidth} + \caption{1-RTT handshake \cite[Figure 3]{I-D.ietf-quic-transport}.} + \includegraphics[width=\linewidth]{images/1RTThandshake.pdf} + \label{fig:1RTThandshake} + \end{subfigure} + \caption{Comparison between 0-RTT and 1-RTT handshakes.} + \label{fig:Comparison-0RTThandshake-1RTThandshake} +\end{figure} + +Figure~\ref{fig:0RTThandshake} shows the QUIC handshake with 0-RTT. +Figure~\ref{fig:1RTThandshake} shows the QUIC handshake with 1-RTT. + +\label{section:0-RTT} +0-RTT connection establishment which recently contacted servers allows the client to send application messages before receiving any messages from the server (early data, see \cite[section~17.2.3]{I-D.ietf-quic-transport}). + +However, 0-RTT lacks certain key security guarantees. In particular, there is no protection against replay attacks in 0-RTT. To enable 0-RTT, QUIC uses connection IDs \cite[section~4.3]{I-D.ietf-quic-invariants} and also provides a way to terminate a connection no longer desired. + +\subsection{CRYPTO typed frames} +To transmit the cryptographic handshake, QUIC relies on \ProtocolElement{CRYPTO} typed frames \cite[section~19.6]{I-D.ietf-quic-transport}. +Each \ProtocolElement{CRYPTO} frame consists in a contiguous block of handshake data and can be sent in all packet types with the exception of 0-RTT. + +As stated in draft IETF QUIC transport \cite[section~19.6]{I-D.ietf-quic-transport} the \ProtocolElement{CRYPTO} frame contains 3~fields: +\begin{itemize} + \item \ProtocolElement{Offset}: A variable-length integer specifying the byte offset in the stream for the data in this \ProtocolElement{CRYPTO} frame. + \item \ProtocolElement{Length}: A variable-length integer specifying the length of the \ProtocolElement{Crypto Data} field in this \ProtocolElement{CRYPTO} frame. + \item \ProtocolElement{Crypto Data}: The cryptographic message data. +\end{itemize} + +There is a separate flow of cryptographic handshake data in each encryption level. Each of these starts at an offset of 0. This implies that each encryption level is treated as a separate \ProtocolElement{CRYPTO} stream of data. + +As opposite to TLS records used with TCP, in QUIC multiple \ProtocolElement{CRYPTO} frames may appear in the same QUIC packet as long as they are associated with the same encryption level \cite[section~4]{I-D.ietf-quic-tls}. + +\subsection{Handshake TLS} + +TLS is a protocol which permits to establish a secure channel between two communicating entities. It simply expected from the underlying transport a reliable, in-order data stream. +TLS function in a client-server mode. It can allow the following security objectives: +\begin{itemize} +\item Authentication: The server has to authenticate; the client may not. +\item Confidentiality of exchanged data. +\item Integrity of exchanged data. +\end{itemize} + +As stated in \cite[section~3]{I-D.ietf-quic-tls}, QUIC provides the confidentiality and integrity of packets by using keys from TLS Handshake. +As with TLS over TCP, once TLS handshake data has been delivered to QUIC, it is QUIC’s responsibility to deliver it reliably. Each chunk of data that is produced by TLS is associated with the set of keys that TLS is currently using. If QUIC needs to retransmit that data, it must use the same keys even if TLS has already updated to newer keys \cite[section~4]{I-D.ietf-quic-tls}. + +TLS Handshake and Alert messages are carried directly over the QUIC transport, which takes over the responsibilities of the TLS record layer, while TCP carries TLS record inside TCP packets payload: unlike TLS over TCP, QUIC applications which want to send data do not send it through TLS \ProtocolElement{application\_data} records \cite[section~3]{I-D.ietf-quic-tls}. + +There are two main interactions between the TLS and QUIC components showed in figure~\ref{fig:QUIC-and-TLS-Interactions}: +\begin{itemize} +\item The TLS component sends and receives messages via the QUIC component, with QUIC providing a reliable stream abstraction to TLS. +\item The TLS component provides a series of updates to the QUIC +component. +\end{itemize} + +\begin{figure}[H] + \centering + \caption{QUIC and TLS Interactions \cite[Figure~4]{I-D.ietf-quic-tls}.} + \includegraphics[width=0.6\linewidth]{images/QUIC-and-TLS-Interactions.pdf} + \label{fig:QUIC-and-TLS-Interactions} +\end{figure} + +As stated in \cite[section~4.8]{I-D.ietf-quic-tls}, in TLS over TCP, the HelloRetryRequest feature can be used to correct a client’s incorrect KeyShare extension as well as for a stateless round-trip check. From the perspective of QUIC, this just looks like additional messages carried in the Initial encryption level. + +The inclusion of the QUIC transport parameters extension ensures that handshake and 1-RTT keys are not the same as those that might be produced by a server running TLS over TCP. To avoid the possibility of cross-protocol key synchronization, additional measures are provided to improve key separation \cite[section~9.5]{I-D.ietf-quic-tls}. + + +\section{Data transfer}\label{section:data-transfer} +In HTTP/2, TCP is used as the transport protocol. Because TCP is reliable and byte-ordered, when multiple streams are multiplexed within the same connection, head-of-line blocking can appear. Head-of-line blocking in TCP is a phenomenon that happens when all the streams of a connection have to wait for a packet of a single stream that is currently lost. This phenomenon occurs because streams are not independent of each other. + +QUIC uses streams just as TCP but they are independent within the same connection. They are identified by a unique numerical value within the connection: the \ProtocolElement{STREAM ID}. This value is a 62-bit integer that can not be reused during the connection. + +Within a QUIC connection, data is therefore sent in \ProtocolElement{STREAM} type frames. +This type of frame is composed of the \ProtocolElement{STREAM ID}, the length of the data sent, the offset within the stream and the data itself. Thanks to the offset, the receiver can reorder data if it does not arrive in order. +If a packet is lost and \ProtocolElement{STREAM} frames were sent within it, only the streams referred by the frames will only have to wait for retransmission. The other streams which are not involved will be able to continue receiving data. + + +\subsection{Loss Detection and Retransmission} +As TCP does, QUIC implements an acknowledgment-based loss detection with TCP's Fast Retransmit, Early Retransmit, FACK, SACK loss recovery, and RACK \cite[section~5.1]{I-D.ietf-quic-recovery} but offers more detailed feedback information for loss detection than TCP \cite[page~74]{innovating-transport-with-quic-Cui-2017}. + +When a packet is received, once packet protection is removed and all the frames in it have been processed, the receiver has to send an acknowledgment to the sender containing the number of the packet received. By receiving it, the sender can know that the packet sent was successfully received and no retransmission is needed. A timer is settled by the sender when a packet is sent. It prevents the sender to wait for an acknowledgment that never arrives. If an arbitrary amount of time, declared during the handshake, expires, the sender will declare the packet as lost. + +In QUIC \cite[section~2]{I-D.ietf-quic-recovery}, an ack-eliciting is a packet that needs to be acknowledged within the maximum delay established. A no ack-eliciting packet is a packet containing \ProtocolElement{ACK}, \ProtocolElement{PADDING} or \ProtocolElement{CONNECTION\_CLOSE} frames. This kind of packet does not need to be acknowledged within the maximum delay established. Therefore, the acknowledgment will be sent only if an ACK frame has to be sent for other reasons. For example, if an ack-eliciting packet arrives, the receiver can acknowledge the packet which just arrives and the non-ack-eliciting packet which arrived before. + +Sending acknowledgments without control can increase the load between the sender and the receiver. The receiver has to balance its sendings. An acknowledgment of an ack-eliciting packet can be delayed as much as the maximum ACK delay time is not exceeded. In some cases, it will wait until more packets arrive to send a packet with more ACK frames rather than sending an acknowledgment every time an ack-eliciting packet arrives. However, an acknowledgment will have to be sent immediately in the following situations: +\begin{itemize} + \item An ack-eliciting packet is received out of order. + \item A packet marked with the ECN-CE (Explicit Congestion Notification - Congestion Experienced, see section~\ref{section:congestion-control}) codepoint is received. +\end{itemize} + +An acknowledgment can only be carried in a packet using the same protection as the packet acknowledged. For example, an acknowledgment for an Application data packet will only be carried in an Application data packet and not in a Handshake packet. + +An ack-eliciting packet will be determined as lost if: +\begin{itemize} + \item The packet is unacknowledged and was sent before and acknowledged packet. + \item No acknowledgement for the packet has arrived in an arbitrary amount of time, maximum acknowledgement delay, that will be established by the endpoint. +\end{itemize} + +If a packet is determined as lost the packet itself is not retransmitted. The information will be retransmitted in a new packet with new frames and only if it is necessary: Data in STREAM frames will not have to be retransmitted if a \ProtocolElement{RESET STREAM} frame is received and data in \ProtocolElement{CRYPTO} frames will not have to be retransmitted if the keys of the encryption level are discarded for example. + +\subsection{Congestion control} \label{section:congestion-control} +QUIC uses TCP’s NewReno \cite[section~6.3]{I-D.ietf-quic-recovery} for congestion control, but unlike TCP, the congestion window is specified in bytes rather than segments. The mechanisms used in TCP to solve congestion problems are therefore implemented in QUIC with a few improvements that should be noted. + +Each QUIC connection begins with a slow start. During slow start, QUIC increases the congestion window by the number of bytes acknowledged when each acknowledgment is processed; and in case of loss, the threshold is lowered to half of the last window and the slow start process is resumed. The slow start process ends once the value of the congestion window exceeds the defined threshold, and it switch to avoidance collision. + +As in TCP, an additive increase multiplicative decrease (AIMD) is used in this phase. It consists of increasing the congestion window by 1 each time until the next loss. When a loss is detected, NewReno halves the congestion window and sets the slow start threshold to the new congestion window. + +The recovery period is slightly different from the TCP recovery definition, which ends when the lost packet that caused the recovery is recognized. Because QUIC does not retransmit lost packets, the end of recovery is achieved when a new packet is sent. +The loss of some packets such as Handshake, 0-RTT, and 1-RTT is ignored when their protection keys are not available when they arrive. + +When persistent congestion is established, the sender's congestion window must be reduced to the minimum congestion window, which is similar to the sender's response on a Retransmission Timeout (RTO) in TCP after Tail Loss Probes(TLP). + +A sender can use the pipeACK method to determine if the congestion window is sufficiently utilized. This underutilization may be due to pacing, which can delay sending packets. However, as in TCP, a sender can implement alternate mechanisms to update its congestion after periods of under-utilization. + +QUIC can also use Explicit Congestion Notification (ECN) to signal network congestion before packet loss occurs. ECN is an IP’s header field. It is only used if both endpoints and the nodes existing in the path can read and understand the ECN field. The use of ECN must be validated by the endpoints during connection establishment and when migrating to another path. This validation, when packets are sent to a host on a new path is done as follows: +\begin{itemize} +\item Setting the ECT(0) code point in the IP header of the first outgoing packets. +\item The validation fails if all packets sent with the ECT(0) code point are lost. +\end{itemize} + +If a receiver receives a QUIC packet without an ECT or CE code point in the IP header it does not increase the number of ECNs. +The QUIC signals which control congestion are generic and are designed to support different algorithms. The use of NewReno is not mandatory as another congestion algorithm exists such as Cubic. Moreover, endpoints can use different algorithms between each other. + +\section{Research issues}\label{section:research-issues} +Various implementations of IETF's QUIC are already available \cite{quic-wg.implementations}. +One of the first available implementations was picoQUIC. This project is a minimal implementation of QUIC aiming to provide feedback on the development of a QUIC standard in the IETF QUIC Working Group \cite{picoquic.impl}. It is actively tested against other implementations. + +Another of the older QUIC implementations is ngtcp2, a community project developed in C. This project provides libraries for client and server roles, with samples of HTTP/3 client and server \cite{ngtcp2.impl}. +quant is a NetApp's implementation providing libraries for both client and server sides \cite{quant.impl}, but it does not implement HTTP/3. + +Quiche is developed by Cloudflare. It provides a low-level API written in Rust for processing QUIC packets. It follows the latest version of QUIC's draft \cite{quiche.impl}. There is a patch for NGINX implementing Cloudflare's Quiche's server role with a Rust to C binding layer \cite{nginx.impl}. + +Recently, HTTP/3 support has been integrated into Curl, although the support is still experimental and needs to be enabled at build time \cite{curl.http3.experimental}. There are two implementations avaible: one using ngtcp2 libraries and the other using quiche's \cite{curl.http3.installation}. + +Neqo has been developed by Mozilla, it implements a client and a server written in Rust. This project aims to be integrated into Gecko and to provide QUIC support to Firefox in the future \cite{neqo.impl}. + +There is also active related work \cite{quic-wg.related-activities} as multipath extension \cite{deconinck-quic-multipath-03}, HTTP over multicast quic \cite{pardue-quic-http-mcast-06}, ns-3 module \cite{1902.06121}, or wireshark integration \cite{quic-wg.tools}. + +\section{General Analysis}\label{section:general-analysis} + +Some criteria have been chosen to recapitulate in a summary table, Table~\ref{tab:comp_tcp_quic}, the differences between QUIC and TCP. These can be classified into two main categories: general and specified criteria related to data transfer and the handshake. + +Firstly, the level of each protocol in the OSI model which marks the possibility of updates in case of a security issue or functionality lack. They help the reader to have a first impression of each protocol. + +Secondly, specified criteria allow an understanding of how each protocol will work in a practical case. The way they manage congestion, handle loss detection and retransmission of packets during data transfer is mandatory for transport protocols to understand the main differences. + +TCP and QUIC both use Header compression with HTTP to transmit data more efficiently, but HTTP/3 design does not allow the use of HPACK because it would induce Head-of-line blocking. QPACK reuses core concepts from HPACK, but is redesigned to allow correctness in the presence of out-of-order delivery, with flexibility for implementations to balance between resilience against head-of-line blocking and optimal compression ratio \cite[section~1]{I-D.ietf-quic-qpack}. + +Being able to do independent streams allows early data transmission and to avoid Head-of-line blocking. The reduction of the RTT during the handshake is significant on networks with high latency and helps reduce the load on operator networks always overloaded. +\begin{table}[H] +\caption {Comparison between TCP and QUIC for sending a secure web page} + \centering + \begin{center} + \begin{tabular}{|p{4.2cm}|p{3.8cm}|p{3.8cm}|} + \hline + \hfil\textbf{Criteria} & \hfil\textbf{TCP (HTTP/2)} & \hfil\textbf{QUIC (HTTP/3)} \\ + \hline + \hfil Layer (OSI model) & \hfil4 & \hfil4.5 \\ + \hline + \hfil Ease of updates & \hfil hard (kernel space) & \hfil easy (user space) \\ + \hline + \hfil Header compression & \hfil HPACK & \hfil QPACK \\ + \hline + \hfil Congestion control algorithm & \multicolumn{2}{c|}{NewReno}\\ + \hline + \hfil Loss detection &\multicolumn{2}{c|}{ using ACK packets and timer}\\ + \hline + \hfil Retransmission packets & \hfil same as lost ones & new packet with same data \\ + \hline + \hfil Independent streams & \hfil no & \hfil yes \\ + \hline + \hfil Early data transmission & \hfil no & if hosts already know each other and are allowed to \\ + \hline + + \end{tabular} + \end{center} + \label{tab:comp_tcp_quic} +\end{table} +\section{Conclusion}\label{section:conclusion} +This paper showed an overview of the QUIC transport protocol. + +The comparison between QUIC and TLS over TCP for a basic web page request showed that many round trips aren't needed to assure speed and security. +HTTP/3 is basically HTTP/2 using QUIC transport protocol, it reduces the number of round trips compared to HTTP over TLS/TCP. + +The use of QUIC doesn't compromise on security (early data responses used in 0-RTT lacks certain key security guarantees). + +The main functionalities of a connected transport protocol for assuring the delivery are designed using already existing algorithms and protocols from TCP. + +QUIC strength is that it's based on UDP transport protocol and this gave freedom of design: one of QUIC's power is to reside in the user space so it is more able to change. + +There is an active community around the development of different implementations as shown in section~\ref{section:research-issues}. +Network analysis tools like ns-3 or Wireshark are the firsts to get QUIC support as they're useful for development. +\newpage +\bibliography{biblio} +\bibliographystyle{splncs04} + +\end{document} diff --git a/splncs04.bst b/splncs04.bst new file mode 100644 index 0000000..3be8de3 --- /dev/null +++ b/splncs04.bst @@ -0,0 +1,1548 @@ +%% BibTeX bibliography style `splncs03' +%% +%% BibTeX bibliography style for use with numbered references in +%% Springer Verlag's "Lecture Notes in Computer Science" series. +%% (See Springer's documentation for llncs.cls for +%% more details of the suggested reference format.) Note that this +%% file will not work for author-year style citations. +%% +%% Use \documentclass{llncs} and \bibliographystyle{splncs03}, and cite +%% a reference with (e.g.) \cite{smith77} to get a "[1]" in the text. +%% +%% This file comes to you courtesy of Maurizio "Titto" Patrignani of +%% Dipartimento di Informatica e Automazione Universita' Roma Tre +%% +%% ================================================================================================ +%% This was file `titto-lncs-02.bst' produced on Wed Apr 1, 2009 +%% Edited by hand by titto based on `titto-lncs-01.bst' (see below) +%% +%% CHANGES (with respect to titto-lncs-01.bst): +%% - Removed the call to \urlprefix (thus no "URL" string is added to the output) +%% ================================================================================================ +%% This was file `titto-lncs-01.bst' produced on Fri Aug 22, 2008 +%% Edited by hand by titto based on `titto.bst' (see below) +%% +%% CHANGES (with respect to titto.bst): +%% - Removed the "capitalize" command for editors string "(eds.)" and "(ed.)" +%% - Introduced the functions titto.bbl.pages and titto.bbl.page for journal pages (without "pp.") +%% - Added a new.sentence command to separate with a dot booktitle and series in the inproceedings +%% - Commented all new.block commands before urls and notes (to separate them with a comma) +%% - Introduced the functions titto.bbl.volume for handling journal volumes (without "vol." label) +%% - Used for editors the same name conventions used for authors (see function format.in.ed.booktitle) +%% - Removed a \newblock to avoid long spaces between title and "In: ..." +%% - Added function titto.space.prefix to add a space instead of "~" after the (removed) "vol." label +%% - Added doi +%% ================================================================================================ +%% This was file `titto.bst', +%% generated with the docstrip utility. +%% +%% The original source files were: +%% +%% merlin.mbs (with options: `vonx,nm-rvvc,yr-par,jttl-rm,volp-com,jwdpg,jwdvol,numser,ser-vol,jnm-x,btit-rm,bt-rm,edparxc,bkedcap,au-col,in-col,fin-bare,pp,ed,abr,mth-bare,xedn,jabr,and-com,and-com-ed,xand,url,url-blk,em-x,nfss,') +%% ---------------------------------------- +%% *** Tentative .bst file for Springer LNCS *** +%% +%% Copyright 1994-2007 Patrick W Daly + % =============================================================== + % IMPORTANT NOTICE: + % This bibliographic style (bst) file has been generated from one or + % more master bibliographic style (mbs) files, listed above. + % + % This generated file can be redistributed and/or modified under the terms + % of the LaTeX Project Public License Distributed from CTAN + % archives in directory macros/latex/base/lppl.txt; either + % version 1 of the License, or any later version. + % =============================================================== + % Name and version information of the main mbs file: + % \ProvidesFile{merlin.mbs}[2007/04/24 4.20 (PWD, AO, DPC)] + % For use with BibTeX version 0.99a or later + %------------------------------------------------------------------- + % This bibliography style file is intended for texts in ENGLISH + % This is a numerical citation style, and as such is standard LaTeX. + % It requires no extra package to interface to the main text. + % The form of the \bibitem entries is + % \bibitem{key}... + % Usage of \cite is as follows: + % \cite{key} ==>> [#] + % \cite[chap. 2]{key} ==>> [#, chap. 2] + % where # is a number determined by the ordering in the reference list. + % The order in the reference list is alphabetical by authors. + %--------------------------------------------------------------------- + +ENTRY + { address + author + booktitle + chapter + doi + edition + editor + eid + howpublished + institution + journal + key + month + note + number + organization + pages + publisher + school + series + title + type + url + volume + year + } + {} + { label } +INTEGERS { output.state before.all mid.sentence after.sentence after.block } +FUNCTION {init.state.consts} +{ #0 'before.all := + #1 'mid.sentence := + #2 'after.sentence := + #3 'after.block := +} +STRINGS { s t} +FUNCTION {output.nonnull} +{ 's := + output.state mid.sentence = + { ", " * write$ } + { output.state after.block = + { add.period$ write$ +% newline$ +% "\newblock " write$ % removed for titto-lncs-01 + " " write$ % to avoid long spaces between title and "In: ..." + } + { output.state before.all = + 'write$ + { add.period$ " " * write$ } + if$ + } + if$ + mid.sentence 'output.state := + } + if$ + s +} +FUNCTION {output} +{ duplicate$ empty$ + 'pop$ + 'output.nonnull + if$ +} +FUNCTION {output.check} +{ 't := + duplicate$ empty$ + { pop$ "empty " t * " in " * cite$ * warning$ } + 'output.nonnull + if$ +} +FUNCTION {fin.entry} +{ duplicate$ empty$ + 'pop$ + 'write$ + if$ + newline$ +} + +FUNCTION {new.block} +{ output.state before.all = + 'skip$ + { after.block 'output.state := } + if$ +} +FUNCTION {new.sentence} +{ output.state after.block = + 'skip$ + { output.state before.all = + 'skip$ + { after.sentence 'output.state := } + if$ + } + if$ +} +FUNCTION {add.blank} +{ " " * before.all 'output.state := +} + + +FUNCTION {add.colon} +{ duplicate$ empty$ + 'skip$ + { ":" * add.blank } + if$ +} + +FUNCTION {date.block} +{ + new.block +} + +FUNCTION {not} +{ { #0 } + { #1 } + if$ +} +FUNCTION {and} +{ 'skip$ + { pop$ #0 } + if$ +} +FUNCTION {or} +{ { pop$ #1 } + 'skip$ + if$ +} +STRINGS {z} +FUNCTION {remove.dots} +{ 'z := + "" + { z empty$ not } + { z #1 #1 substring$ + z #2 global.max$ substring$ 'z := + duplicate$ "." = 'pop$ + { * } + if$ + } + while$ +} +FUNCTION {new.block.checka} +{ empty$ + 'skip$ + 'new.block + if$ +} +FUNCTION {new.block.checkb} +{ empty$ + swap$ empty$ + and + 'skip$ + 'new.block + if$ +} +FUNCTION {new.sentence.checka} +{ empty$ + 'skip$ + 'new.sentence + if$ +} +FUNCTION {new.sentence.checkb} +{ empty$ + swap$ empty$ + and + 'skip$ + 'new.sentence + if$ +} +FUNCTION {field.or.null} +{ duplicate$ empty$ + { pop$ "" } + 'skip$ + if$ +} +FUNCTION {emphasize} +{ skip$ } + +FUNCTION {embolden} +{ duplicate$ empty$ +{ pop$ "" } +{ "\textbf{" swap$ * "}" * } +if$ +} +FUNCTION {tie.or.space.prefix} +{ duplicate$ text.length$ #5 < + { "~" } + { " " } + if$ + swap$ +} +FUNCTION {titto.space.prefix} % always introduce a space +{ duplicate$ text.length$ #3 < + { " " } + { " " } + if$ + swap$ +} + + +FUNCTION {capitalize} +{ "u" change.case$ "t" change.case$ } + +FUNCTION {space.word} +{ " " swap$ * " " * } + % Here are the language-specific definitions for explicit words. + % Each function has a name bbl.xxx where xxx is the English word. + % The language selected here is ENGLISH +FUNCTION {bbl.and} +{ "and"} + +FUNCTION {bbl.etal} +{ "et~al." } + +FUNCTION {bbl.editors} +{ "eds." } + +FUNCTION {bbl.editor} +{ "ed." } + +FUNCTION {bbl.edby} +{ "edited by" } + +FUNCTION {bbl.edition} +{ "edn." } + +FUNCTION {bbl.volume} +{ "vol." } + +FUNCTION {titto.bbl.volume} % for handling journals +{ "" } + +FUNCTION {bbl.of} +{ "of" } + +FUNCTION {bbl.number} +{ "no." } + +FUNCTION {bbl.nr} +{ "no." } + +FUNCTION {bbl.in} +{ "in" } + +FUNCTION {bbl.pages} +{ "pp." } + +FUNCTION {bbl.page} +{ "p." } + +FUNCTION {titto.bbl.pages} % for journals +{ "" } + +FUNCTION {titto.bbl.page} % for journals +{ "" } + +FUNCTION {bbl.chapter} +{ "chap." } + +FUNCTION {bbl.techrep} +{ "Tech. Rep." } + +FUNCTION {bbl.mthesis} +{ "Master's thesis" } + +FUNCTION {bbl.phdthesis} +{ "Ph.D. thesis" } + +MACRO {jan} {"Jan."} + +MACRO {feb} {"Feb."} + +MACRO {mar} {"Mar."} + +MACRO {apr} {"Apr."} + +MACRO {may} {"May"} + +MACRO {jun} {"Jun."} + +MACRO {jul} {"Jul."} + +MACRO {aug} {"Aug."} + +MACRO {sep} {"Sep."} + +MACRO {oct} {"Oct."} + +MACRO {nov} {"Nov."} + +MACRO {dec} {"Dec."} + +MACRO {acmcs} {"ACM Comput. Surv."} + +MACRO {acta} {"Acta Inf."} + +MACRO {cacm} {"Commun. ACM"} + +MACRO {ibmjrd} {"IBM J. Res. Dev."} + +MACRO {ibmsj} {"IBM Syst.~J."} + +MACRO {ieeese} {"IEEE Trans. Software Eng."} + +MACRO {ieeetc} {"IEEE Trans. Comput."} + +MACRO {ieeetcad} + {"IEEE Trans. Comput. Aid. Des."} + +MACRO {ipl} {"Inf. Process. Lett."} + +MACRO {jacm} {"J.~ACM"} + +MACRO {jcss} {"J.~Comput. Syst. Sci."} + +MACRO {scp} {"Sci. Comput. Program."} + +MACRO {sicomp} {"SIAM J. Comput."} + +MACRO {tocs} {"ACM Trans. Comput. Syst."} + +MACRO {tods} {"ACM Trans. Database Syst."} + +MACRO {tog} {"ACM Trans. Graphic."} + +MACRO {toms} {"ACM Trans. Math. Software"} + +MACRO {toois} {"ACM Trans. Office Inf. Syst."} + +MACRO {toplas} {"ACM Trans. Progr. Lang. Syst."} + +MACRO {tcs} {"Theor. Comput. Sci."} + +FUNCTION {bibinfo.check} +{ swap$ + duplicate$ missing$ + { + pop$ pop$ + "" + } + { duplicate$ empty$ + { + swap$ pop$ + } + { swap$ + pop$ + } + if$ + } + if$ +} +FUNCTION {bibinfo.warn} +{ swap$ + duplicate$ missing$ + { + swap$ "missing " swap$ * " in " * cite$ * warning$ pop$ + "" + } + { duplicate$ empty$ + { + swap$ "empty " swap$ * " in " * cite$ * warning$ + } + { swap$ + pop$ + } + if$ + } + if$ +} +FUNCTION {format.url} +{ url empty$ + { "" } +% { "\urlprefix\url{" url * "}" * } + { "\url{" url * "}" * } % changed in titto-lncs-02.bst + if$ +} + +FUNCTION {format.doi} % added in splncs04.bst +{ doi empty$ + { "" } + { after.block 'output.state := + "\doi{" doi * "}" * } + if$ +} + +INTEGERS { nameptr namesleft numnames } + + +STRINGS { bibinfo} + +FUNCTION {format.names} +{ 'bibinfo := + duplicate$ empty$ 'skip$ { + 's := + "" 't := + #1 'nameptr := + s num.names$ 'numnames := + numnames 'namesleft := + { namesleft #0 > } + { s nameptr + "{vv~}{ll}{, jj}{, f{.}.}" + format.name$ + bibinfo bibinfo.check + 't := + nameptr #1 > + { + namesleft #1 > + { ", " * t * } + { + s nameptr "{ll}" format.name$ duplicate$ "others" = + { 't := } + { pop$ } + if$ + "," * + t "others" = + { + " " * bbl.etal * + } + { " " * t * } + if$ + } + if$ + } + 't + if$ + nameptr #1 + 'nameptr := + namesleft #1 - 'namesleft := + } + while$ + } if$ +} +FUNCTION {format.names.ed} +{ + 'bibinfo := + duplicate$ empty$ 'skip$ { + 's := + "" 't := + #1 'nameptr := + s num.names$ 'numnames := + numnames 'namesleft := + { namesleft #0 > } + { s nameptr + "{f{.}.~}{vv~}{ll}{ jj}" + format.name$ + bibinfo bibinfo.check + 't := + nameptr #1 > + { + namesleft #1 > + { ", " * t * } + { + s nameptr "{ll}" format.name$ duplicate$ "others" = + { 't := } + { pop$ } + if$ + "," * + t "others" = + { + + " " * bbl.etal * + } + { " " * t * } + if$ + } + if$ + } + 't + if$ + nameptr #1 + 'nameptr := + namesleft #1 - 'namesleft := + } + while$ + } if$ +} +FUNCTION {format.authors} +{ author "author" format.names +} +FUNCTION {get.bbl.editor} +{ editor num.names$ #1 > 'bbl.editors 'bbl.editor if$ } + +FUNCTION {format.editors} +{ editor "editor" format.names duplicate$ empty$ 'skip$ + { + " " * + get.bbl.editor +% capitalize + "(" swap$ * ")" * + * + } + if$ +} +FUNCTION {format.note} +{ + note empty$ + { "" } + { note #1 #1 substring$ + duplicate$ "{" = + 'skip$ + { output.state mid.sentence = + { "l" } + { "u" } + if$ + change.case$ + } + if$ + note #2 global.max$ substring$ * "note" bibinfo.check + } + if$ +} + +FUNCTION {format.title} +{ title + duplicate$ empty$ 'skip$ + { "t" change.case$ } + if$ + "title" bibinfo.check +} +FUNCTION {output.bibitem} +{ newline$ + "\bibitem{" write$ + cite$ write$ + "}" write$ + newline$ + "" + before.all 'output.state := +} + +FUNCTION {n.dashify} +{ + 't := + "" + { t empty$ not } + { t #1 #1 substring$ "-" = + { t #1 #2 substring$ "--" = not + { "--" * + t #2 global.max$ substring$ 't := + } + { { t #1 #1 substring$ "-" = } + { "-" * + t #2 global.max$ substring$ 't := + } + while$ + } + if$ + } + { t #1 #1 substring$ * + t #2 global.max$ substring$ 't := + } + if$ + } + while$ +} + +FUNCTION {word.in} +{ bbl.in capitalize + ":" * + " " * } + +FUNCTION {format.date} +{ + month "month" bibinfo.check + duplicate$ empty$ + year "year" bibinfo.check duplicate$ empty$ + { swap$ 'skip$ + { "there's a month but no year in " cite$ * warning$ } + if$ + * + } + { swap$ 'skip$ + { + swap$ + " " * swap$ + } + if$ + * + remove.dots + } + if$ + duplicate$ empty$ + 'skip$ + { + before.all 'output.state := + " (" swap$ * ")" * + } + if$ +} +FUNCTION {format.btitle} +{ title "title" bibinfo.check + duplicate$ empty$ 'skip$ + { + } + if$ +} +FUNCTION {either.or.check} +{ empty$ + 'pop$ + { "can't use both " swap$ * " fields in " * cite$ * warning$ } + if$ +} +FUNCTION {format.bvolume} +{ volume empty$ + { "" } + { bbl.volume volume tie.or.space.prefix + "volume" bibinfo.check * * + series "series" bibinfo.check + duplicate$ empty$ 'pop$ + { emphasize ", " * swap$ * } + if$ + "volume and number" number either.or.check + } + if$ +} +FUNCTION {format.number.series} +{ volume empty$ + { number empty$ + { series field.or.null } + { output.state mid.sentence = + { bbl.number } + { bbl.number capitalize } + if$ + number tie.or.space.prefix "number" bibinfo.check * * + series empty$ + { "there's a number but no series in " cite$ * warning$ } + { bbl.in space.word * + series "series" bibinfo.check * + } + if$ + } + if$ + } + { "" } + if$ +} + +FUNCTION {format.edition} +{ edition duplicate$ empty$ 'skip$ + { + output.state mid.sentence = + { "l" } + { "t" } + if$ change.case$ + "edition" bibinfo.check + " " * bbl.edition * + } + if$ +} +INTEGERS { multiresult } +FUNCTION {multi.page.check} +{ 't := + #0 'multiresult := + { multiresult not + t empty$ not + and + } + { t #1 #1 substring$ + duplicate$ "-" = + swap$ duplicate$ "," = + swap$ "+" = + or or + { #1 'multiresult := } + { t #2 global.max$ substring$ 't := } + if$ + } + while$ + multiresult +} +FUNCTION {format.pages} +{ pages duplicate$ empty$ 'skip$ + { duplicate$ multi.page.check + { + bbl.pages swap$ + n.dashify + } + { + bbl.page swap$ + } + if$ + tie.or.space.prefix + "pages" bibinfo.check + * * + } + if$ +} +FUNCTION {format.journal.pages} +{ pages duplicate$ empty$ 'pop$ + { swap$ duplicate$ empty$ + { pop$ pop$ format.pages } + { + ", " * + swap$ + n.dashify + pages multi.page.check + 'titto.bbl.pages + 'titto.bbl.page + if$ + swap$ tie.or.space.prefix + "pages" bibinfo.check + * * + * + } + if$ + } + if$ +} +FUNCTION {format.journal.eid} +{ eid "eid" bibinfo.check + duplicate$ empty$ 'pop$ + { swap$ duplicate$ empty$ 'skip$ + { + ", " * + } + if$ + swap$ * + } + if$ +} +FUNCTION {format.vol.num.pages} % this function is used only for journal entries +{ volume field.or.null embolden + duplicate$ empty$ 'skip$ + { +% bbl.volume swap$ tie.or.space.prefix + titto.bbl.volume swap$ titto.space.prefix +% rationale for the change above: for journals you don't want "vol." label +% hence it does not make sense to attach the journal number to the label when +% it is short + "volume" bibinfo.check + * * + } + if$ + number "number" bibinfo.check duplicate$ empty$ 'skip$ + { + swap$ duplicate$ empty$ + { "there's a number but no volume in " cite$ * warning$ } + 'skip$ + if$ + swap$ + "(" swap$ * ")" * + } + if$ * + eid empty$ + { format.journal.pages } + { format.journal.eid } + if$ +} + +FUNCTION {format.chapter.pages} +{ chapter empty$ + 'format.pages + { type empty$ + { bbl.chapter } + { type "l" change.case$ + "type" bibinfo.check + } + if$ + chapter tie.or.space.prefix + "chapter" bibinfo.check + * * + pages empty$ + 'skip$ + { ", " * format.pages * } + if$ + } + if$ +} + +FUNCTION {format.booktitle} +{ + booktitle "booktitle" bibinfo.check +} +FUNCTION {format.in.ed.booktitle} +{ format.booktitle duplicate$ empty$ 'skip$ + { +% editor "editor" format.names.ed duplicate$ empty$ 'pop$ % changed by titto + editor "editor" format.names duplicate$ empty$ 'pop$ + { + " " * + get.bbl.editor +% capitalize + "(" swap$ * ") " * + * swap$ + * } + if$ + word.in swap$ * + } + if$ +} +FUNCTION {empty.misc.check} +{ author empty$ title empty$ howpublished empty$ + month empty$ year empty$ note empty$ + and and and and and + key empty$ not and + { "all relevant fields are empty in " cite$ * warning$ } + 'skip$ + if$ +} +FUNCTION {format.thesis.type} +{ type duplicate$ empty$ + 'pop$ + { swap$ pop$ + "t" change.case$ "type" bibinfo.check + } + if$ +} +FUNCTION {format.tr.number} +{ number "number" bibinfo.check + type duplicate$ empty$ + { pop$ bbl.techrep } + 'skip$ + if$ + "type" bibinfo.check + swap$ duplicate$ empty$ + { pop$ "t" change.case$ } + { tie.or.space.prefix * * } + if$ +} +FUNCTION {format.article.crossref} +{ + key duplicate$ empty$ + { pop$ + journal duplicate$ empty$ + { "need key or journal for " cite$ * " to crossref " * crossref * warning$ } + { "journal" bibinfo.check emphasize word.in swap$ * } + if$ + } + { word.in swap$ * " " *} + if$ + " \cite{" * crossref * "}" * +} +FUNCTION {format.crossref.editor} +{ editor #1 "{vv~}{ll}" format.name$ + "editor" bibinfo.check + editor num.names$ duplicate$ + #2 > + { pop$ + "editor" bibinfo.check + " " * bbl.etal + * + } + { #2 < + 'skip$ + { editor #2 "{ff }{vv }{ll}{ jj}" format.name$ "others" = + { + "editor" bibinfo.check + " " * bbl.etal + * + } + { + bbl.and space.word + * editor #2 "{vv~}{ll}" format.name$ + "editor" bibinfo.check + * + } + if$ + } + if$ + } + if$ +} +FUNCTION {format.book.crossref} +{ volume duplicate$ empty$ + { "empty volume in " cite$ * "'s crossref of " * crossref * warning$ + pop$ word.in + } + { bbl.volume + capitalize + swap$ tie.or.space.prefix "volume" bibinfo.check * * bbl.of space.word * + } + if$ + editor empty$ + editor field.or.null author field.or.null = + or + { key empty$ + { series empty$ + { "need editor, key, or series for " cite$ * " to crossref " * + crossref * warning$ + "" * + } + { series emphasize * } + if$ + } + { key * } + if$ + } + { format.crossref.editor * } + if$ + " \cite{" * crossref * "}" * +} +FUNCTION {format.incoll.inproc.crossref} +{ + editor empty$ + editor field.or.null author field.or.null = + or + { key empty$ + { format.booktitle duplicate$ empty$ + { "need editor, key, or booktitle for " cite$ * " to crossref " * + crossref * warning$ + } + { word.in swap$ * } + if$ + } + { word.in key * " " *} + if$ + } + { word.in format.crossref.editor * " " *} + if$ + " \cite{" * crossref * "}" * +} +FUNCTION {format.org.or.pub} +{ 't := + "" + address empty$ t empty$ and + 'skip$ + { + t empty$ + { address "address" bibinfo.check * + } + { t * + address empty$ + 'skip$ + { ", " * address "address" bibinfo.check * } + if$ + } + if$ + } + if$ +} +FUNCTION {format.publisher.address} +{ publisher "publisher" bibinfo.warn format.org.or.pub +} + +FUNCTION {format.organization.address} +{ organization "organization" bibinfo.check format.org.or.pub +} + +FUNCTION {article} +{ output.bibitem + format.authors "author" output.check + add.colon + new.block + format.title "title" output.check + new.block + crossref missing$ + { + journal + "journal" bibinfo.check + "journal" output.check + add.blank + format.vol.num.pages output + format.date "year" output.check + } + { format.article.crossref output.nonnull + format.pages output + } + if$ +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} +FUNCTION {book} +{ output.bibitem + author empty$ + { format.editors "author and editor" output.check + add.colon + } + { format.authors output.nonnull + add.colon + crossref missing$ + { "author and editor" editor either.or.check } + 'skip$ + if$ + } + if$ + new.block + format.btitle "title" output.check + crossref missing$ + { format.bvolume output + new.block + new.sentence + format.number.series output + format.publisher.address output + } + { + new.block + format.book.crossref output.nonnull + } + if$ + format.edition output + format.date "year" output.check +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} +FUNCTION {booklet} +{ output.bibitem + format.authors output + add.colon + new.block + format.title "title" output.check + new.block + howpublished "howpublished" bibinfo.check output + address "address" bibinfo.check output + format.date output +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} + +FUNCTION {inbook} +{ output.bibitem + author empty$ + { format.editors "author and editor" output.check + add.colon + } + { format.authors output.nonnull + add.colon + crossref missing$ + { "author and editor" editor either.or.check } + 'skip$ + if$ + } + if$ + new.block + format.btitle "title" output.check + crossref missing$ + { + format.bvolume output + format.chapter.pages "chapter and pages" output.check + new.block + new.sentence + format.number.series output + format.publisher.address output + } + { + format.chapter.pages "chapter and pages" output.check + new.block + format.book.crossref output.nonnull + } + if$ + format.edition output + format.date "year" output.check +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} + +FUNCTION {incollection} +{ output.bibitem + format.authors "author" output.check + add.colon + new.block + format.title "title" output.check + new.block + crossref missing$ + { format.in.ed.booktitle "booktitle" output.check + format.bvolume output + format.chapter.pages output + new.sentence + format.number.series output + format.publisher.address output + format.edition output + format.date "year" output.check + } + { format.incoll.inproc.crossref output.nonnull + format.chapter.pages output + } + if$ +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} +FUNCTION {inproceedings} +{ output.bibitem + format.authors "author" output.check + add.colon + new.block + format.title "title" output.check + new.block + crossref missing$ + { format.in.ed.booktitle "booktitle" output.check + new.sentence % added by titto + format.bvolume output + format.pages output + new.sentence + format.number.series output + publisher empty$ + { format.organization.address output } + { organization "organization" bibinfo.check output + format.publisher.address output + } + if$ + format.date "year" output.check + } + { format.incoll.inproc.crossref output.nonnull + format.pages output + } + if$ +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} +FUNCTION {conference} { inproceedings } +FUNCTION {manual} +{ output.bibitem + author empty$ + { organization "organization" bibinfo.check + duplicate$ empty$ 'pop$ + { output + address "address" bibinfo.check output + } + if$ + } + { format.authors output.nonnull } + if$ + add.colon + new.block + format.btitle "title" output.check + author empty$ + { organization empty$ + { + address new.block.checka + address "address" bibinfo.check output + } + 'skip$ + if$ + } + { + organization address new.block.checkb + organization "organization" bibinfo.check output + address "address" bibinfo.check output + } + if$ + format.edition output + format.date output +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} + +FUNCTION {mastersthesis} +{ output.bibitem + format.authors "author" output.check + add.colon + new.block + format.btitle + "title" output.check + new.block + bbl.mthesis format.thesis.type output.nonnull + school "school" bibinfo.warn output + address "address" bibinfo.check output + format.date "year" output.check +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} + +FUNCTION {misc} +{ output.bibitem + format.authors output + add.colon + title howpublished new.block.checkb + format.title output + howpublished new.block.checka + howpublished "howpublished" bibinfo.check output + format.date output +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry + empty.misc.check +} +FUNCTION {phdthesis} +{ output.bibitem + format.authors "author" output.check + add.colon + new.block + format.btitle + "title" output.check + new.block + bbl.phdthesis format.thesis.type output.nonnull + school "school" bibinfo.warn output + address "address" bibinfo.check output + format.date "year" output.check +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} + +FUNCTION {proceedings} +{ output.bibitem + editor empty$ + { organization "organization" bibinfo.check output + } + { format.editors output.nonnull } + if$ + add.colon + new.block + format.btitle "title" output.check + format.bvolume output + editor empty$ + { publisher empty$ + { format.number.series output } + { + new.sentence + format.number.series output + format.publisher.address output + } + if$ + } + { publisher empty$ + { + new.sentence + format.number.series output + format.organization.address output } + { + new.sentence + format.number.series output + organization "organization" bibinfo.check output + format.publisher.address output + } + if$ + } + if$ + format.date "year" output.check +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} + +FUNCTION {techreport} +{ output.bibitem + format.authors "author" output.check + add.colon + new.block + format.title + "title" output.check + new.block + format.tr.number output.nonnull + institution "institution" bibinfo.warn output + address "address" bibinfo.check output + format.date "year" output.check +% new.block + format.doi output + format.url output +% new.block + format.note output + fin.entry +} + +FUNCTION {unpublished} +{ output.bibitem + format.authors "author" output.check + add.colon + new.block + format.title "title" output.check + format.date output +% new.block + format.url output +% new.block + format.note "note" output.check + fin.entry +} + +FUNCTION {default.type} { misc } +READ +FUNCTION {sortify} +{ purify$ + "l" change.case$ +} +INTEGERS { len } +FUNCTION {chop.word} +{ 's := + 'len := + s #1 len substring$ = + { s len #1 + global.max$ substring$ } + 's + if$ +} +FUNCTION {sort.format.names} +{ 's := + #1 'nameptr := + "" + s num.names$ 'numnames := + numnames 'namesleft := + { namesleft #0 > } + { s nameptr + "{ll{ }}{ ff{ }}{ jj{ }}" + format.name$ 't := + nameptr #1 > + { + " " * + namesleft #1 = t "others" = and + { "zzzzz" * } + { t sortify * } + if$ + } + { t sortify * } + if$ + nameptr #1 + 'nameptr := + namesleft #1 - 'namesleft := + } + while$ +} + +FUNCTION {sort.format.title} +{ 't := + "A " #2 + "An " #3 + "The " #4 t chop.word + chop.word + chop.word + sortify + #1 global.max$ substring$ +} +FUNCTION {author.sort} +{ author empty$ + { key empty$ + { "to sort, need author or key in " cite$ * warning$ + "" + } + { key sortify } + if$ + } + { author sort.format.names } + if$ +} +FUNCTION {author.editor.sort} +{ author empty$ + { editor empty$ + { key empty$ + { "to sort, need author, editor, or key in " cite$ * warning$ + "" + } + { key sortify } + if$ + } + { editor sort.format.names } + if$ + } + { author sort.format.names } + if$ +} +FUNCTION {author.organization.sort} +{ author empty$ + { organization empty$ + { key empty$ + { "to sort, need author, organization, or key in " cite$ * warning$ + "" + } + { key sortify } + if$ + } + { "The " #4 organization chop.word sortify } + if$ + } + { author sort.format.names } + if$ +} +FUNCTION {editor.organization.sort} +{ editor empty$ + { organization empty$ + { key empty$ + { "to sort, need editor, organization, or key in " cite$ * warning$ + "" + } + { key sortify } + if$ + } + { "The " #4 organization chop.word sortify } + if$ + } + { editor sort.format.names } + if$ +} +FUNCTION {presort} +{ type$ "book" = + type$ "inbook" = + or + 'author.editor.sort + { type$ "proceedings" = + 'editor.organization.sort + { type$ "manual" = + 'author.organization.sort + 'author.sort + if$ + } + if$ + } + if$ + " " + * + year field.or.null sortify + * + " " + * + title field.or.null + sort.format.title + * + #1 entry.max$ substring$ + 'sort.key$ := +} +ITERATE {presort} +SORT +STRINGS { longest.label } +INTEGERS { number.label longest.label.width } +FUNCTION {initialize.longest.label} +{ "" 'longest.label := + #1 'number.label := + #0 'longest.label.width := +} +FUNCTION {longest.label.pass} +{ number.label int.to.str$ 'label := + number.label #1 + 'number.label := + label width$ longest.label.width > + { label 'longest.label := + label width$ 'longest.label.width := + } + 'skip$ + if$ +} +EXECUTE {initialize.longest.label} +ITERATE {longest.label.pass} +FUNCTION {begin.bib} +{ preamble$ empty$ + 'skip$ + { preamble$ write$ newline$ } + if$ + "\begin{thebibliography}{" longest.label * "}" * + write$ newline$ + "\providecommand{\url}[1]{\texttt{#1}}" + write$ newline$ + "\providecommand{\urlprefix}{URL }" + write$ newline$ + "\providecommand{\doi}[1]{https://doi.org/#1}" + write$ newline$ +} +EXECUTE {begin.bib} +EXECUTE {init.state.consts} +ITERATE {call.type$} +FUNCTION {end.bib} +{ newline$ + "\end{thebibliography}" write$ newline$ +} +EXECUTE {end.bib} +%% End of customized bst file +%% +%% End of file `titto.bst'.