todo

DCCP协议在linux下的C编程实现 linux C

Bugs to fix:
- Killing the server while the client is still connected causes a kernel panic
  on the machine running the server.
- Killing the server while the client is NOT connected causes a kernel panic on
  the machine running the server. Seems to panic at sched.c:557 which indicates
  interrupt called during scheduling which means probably not correct locks
  implemented in DCCP kernel I would guess
- Assuming we're using version 1 of the draft DCCP specification, initial
  sequence number needs to be randomly set. Not 100% sure this is being done
  currently.
- Doubts regarding the for loop that deals with an ASK option where a CCID
  change is requested in function generic_option_parse. It does not appear to
  appropriately handle multiple CCID suggestions correctly. A proposed solution
  can be found in source code so it is just a matter of implementing and
  testing it.
- DCCP Prefer options only allow a single preferred value for a feature.
  Multiple preferences should be supported.
- Acks are not credited under CCID 2 - the function calls are commented out.
  Seems easy to fix, I'm not sure if there is a bigger underlying problem yet
  that caused someone to comment them out initially.
- dccp_add_option doesn't update tp->opt_a_sz correctly. It should be "+ optlen
  + 2" but according to someone who worked on this before me adding +2 creates
  a DOS attack. It really should be +2 though!

Changes to make:
- Migrate to kernel 2.6.x (underway)
- Move to latest version of specs
- Change c name from dcp.c to dccp.c (done in development tree)
- Change symbol CONFIG_NET_DCP to CONFIG_NET_DCCP (done in development tree)
- Put include files in correct place for dccp headers
- Make work as part of kernel as well as a module (done under previous release
  but not tested)