sctp: add support for SCTP_REUSE_PORT sockopt

This feature is actually already supported by sk->sk_reuse which can be set by socket level opt SO_REUSEADDR. But it's not working exactly as RFC6458 demands in section 8.1.27, like: - This option only supports one-to-one style SCTP sockets - This socket option must not be used after calling bind() or sctp_bindx(). Besides, SCTP_REUSE_PORT sockopt should be provided for user's programs. Otherwise, the programs with SCTP_REUSE_PORT from other systems will not work in linux. To separate it from the socket level version, this patch adds 'reuse' in sctp_sock and it works pretty much as sk->sk_reuse, but with some extra setup limitations that are needed when it is being enabled. "It should be noted that the behavior of the socket-level socket option to reuse ports and/or addresses for SCTP sockets is unspecified", so it leaves SO_REUSEADDR as is for the compatibility. Note that the name SCTP_REUSE_PORT is somewhat confusing, as its functionality is nearly identical to SO_REUSEADDR, but with some extra restrictions. Here it uses 'reuse' in sctp_sock instead of 'reuseport'. As for sk->sk_reuseport support for SCTP, it will be added in another patch. Thanks to Neil to make this clear. v1->v2: - add sctp_sk->reuse to separate it from the socket level version. v2->v3: - improve changelog according to Marcelo's suggestion.

Xin Long committed 8 years ago

Commit b0e9a2f1 parent 23c94d63 files · +57 −7Browse files

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include/uapi/linux/sctp.h+1−0

@@ -100,6 +100,7 @@ typedef __s32 sctp_assoc_t; · 99 unmodified lines
100	#define SCTP_RECVNXTINFO 33	100	#define SCTP_RECVNXTINFO 33
101	#define SCTP_DEFAULT_SNDINFO 34	101	#define SCTP_DEFAULT_SNDINFO 34
102	#define SCTP_AUTH_DEACTIVATE_KEY 35	102	#define SCTP_AUTH_DEACTIVATE_KEY 35
		103	#define SCTP_REUSE_PORT 36
103		104
104	/* Internal Socket Options. Some of the sctp library functions are	105	/* Internal Socket Options. Some of the sctp library functions are
105	* implemented using these socket options.	106	* implemented using these socket options.