Projet_JAVA_P2P_STRI2A/doc/protocol.md

P2P-JAVA-PROJECT version 1 (Protocol for step 1)

All messages begins with P2P-JAVA-PROJECT VERSION 1.0\n (this version of the protocol).

Client messages

• LIST\n: ask the server to list files from server root directory
• DOWNLOAD\n<FILENAME>\n: ask the server to download file from server root directory. Only one filename is allowed per request.

Server responses

• The response to LIST request is in the format LIST\n<FILENAME 1>\n<FILENAME 2>\n[…]<LAST FILENAME>\n\n
• The response to DOWNLOAD request is LOAD\n<FILESIZE (BYTES)>\n<POSITION>\n<CONTENT OF FILE> or NOT FOUND\n if the file doesn't exists.
• The server send a PROTOCOL ERROR\n message if it doesn't understands what the client sent.
• The server send a INTERNAL ERROR\n message if it encounters an internal error.

P2P-JAVA-PROJECT version 1.1 (Binary protocol for step 1)

[0-7: VERSION(0x11, first quartet is major version, second is minor)]
[8-15: REQUEST/RESPONSE CODE]
[16-31: RESERVED FOR FUTURE USE]
[32-63: PAYLOAD SIZE IN BYTES]
[64-xx: PAYLOAD]

Requests and responses codes

• REQUESTS (msb is 0):

  • LIST (0x00)
  • DOWNLOAD (0x01)

• RESPONSES (msb is 1):

  • LIST (0x80)
  • LOAD (0x81)
  • NOT FOUND (0x82)
  • PROTOCOL ERROR (0x83)
  • INTERNAL ERROR (0x84)

List

Payload size for list request is always zero. Payload for list response is filenames separated by \n.

Download

Not found

Response when the file requested is not found on the server. Payload size for Not found is zero

Protocol error

Response when the request cannot be interpreted. Payload size for Protocol error is zero

Internal error

Response in internal failure case. Payload size for Internal error is zero

Load response

Payload contains

[64-127: OFFSET OF FILE CONTENT IN BYTES]
[128-159: TOTAL FILESIZE]
[<FILENAME>\n]
[FILE CONTENT]