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| author |   Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2007-10-04 14:39:22 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@sunset.davemloft.net> | 2007-10-10 16:54:31 -0700 |
| commit | 7c559a9e44ee61faf2f339604ce708decb345a93 (patch) | |
| tree | 8e0e89521445a42cf801747af20be172b6e9e582 /net/dccp/proto.c | |
| parent | [DCCP]: Wait for CCID (diff) | |
| download | linux-dev-7c559a9e44ee61faf2f339604ce708decb345a93.tar.xz linux-dev-7c559a9e44ee61faf2f339604ce708decb345a93.zip | |
[DCCP]: Add socket option to query the current MPS
This enables applications to query the current value of the Maximum
Packet Size via a socket option, suggested as a SHOULD in (RFC 4340,
p. 102).
This socket option is useful to avoid the annoying bail-out via
`-EMSGSIZE'. In particular, as fragmentation is not currently
supported (and its use is partly discouraged in RFC 4340).
With this option, it is possible to size buffers accordingly, e.g.
int buflen = dccp_get_cur_mps(sockfd);
/* or */
if (msgsize > dccp_get_cur_mps(sockfd))
die("message is too large for this path");
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
| -rw-r--r-- | net/dccp/proto.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/dccp/proto.c b/net/dccp/proto.c index 7e4f54a4ecaf..c0b685efe245 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -587,6 +587,10 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname, case DCCP_SOCKOPT_SERVICE: return dccp_getsockopt_service(sk, len, (__be32 __user *)optval, optlen); + case DCCP_SOCKOPT_GET_CUR_MPS: + val = dp->dccps_mss_cache; + len = sizeof(val); + break; case DCCP_SOCKOPT_SEND_CSCOV: val = dp->dccps_pcslen; len = sizeof(val); |