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| author | samanthakumar <samanthakumar@google.com> | 2016-04-05 12:41:16 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-04-05 16:29:37 -0400 |
| commit | 627d2d6b550094d88f9e518e15967e7bf906ebbf (patch) | |
| tree | 4a4d64af861781920b2b4ef6d0e7b4423b787292 /net/ipv4/udp.c | |
| parent | e6afc8ace6dd5cef5e812f26c72579da8806f5ac (diff) | |
| download | linux-627d2d6b550094d88f9e518e15967e7bf906ebbf.tar.gz linux-627d2d6b550094d88f9e518e15967e7bf906ebbf.tar.xz | |
udp: enable MSG_PEEK at non-zero offset
Enable peeking at UDP datagrams at the offset specified with socket
option SOL_SOCKET/SO_PEEK_OFF. Peek at any datagram in the queue, up
to the end of the given datagram.
Implement the SO_PEEK_OFF semantics introduced in commit ef64a54f6e55
("sock: Introduce the SO_PEEK_OFF sock option"). Increase the offset
on peek, decrease it on regular reads.
When peeking, always checksum the packet immediately, to avoid
recomputation on subsequent peeks and final read.
The socket lock is not held for the duration of udp_recvmsg, so
peek and read operations can run concurrently. Only the last store
to sk_peek_off is preserved.
Signed-off-by: Sam Kumar <samanthakumar@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/udp.c')
| -rw-r--r-- | net/ipv4/udp.c | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index cf747e86ce52..d80312ddbb8a 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1294,7 +1294,7 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock, DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name); struct sk_buff *skb; unsigned int ulen, copied; - int peeked, off = 0; + int peeked, peeking, off; int err; int is_udplite = IS_UDPLITE(sk); bool checksum_valid = false; @@ -1304,15 +1304,16 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock, return ip_recv_error(sk, msg, len, addr_len); try_again: + peeking = off = sk_peek_offset(sk, flags); skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0), &peeked, &off, &err); if (!skb) - goto out; + return err; ulen = skb->len; copied = len; - if (copied > ulen) - copied = ulen; + if (copied > ulen - off) + copied = ulen - off; else if (copied < ulen) msg->msg_flags |= MSG_TRUNC; @@ -1322,16 +1323,16 @@ try_again: * coverage checksum (UDP-Lite), do it before the copy. */ - if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) { + if (copied < ulen || UDP_SKB_CB(skb)->partial_cov || peeking) { checksum_valid = !udp_lib_checksum_complete(skb); if (!checksum_valid) goto csum_copy_err; } if (checksum_valid || skb_csum_unnecessary(skb)) - err = skb_copy_datagram_msg(skb, 0, msg, copied); + err = skb_copy_datagram_msg(skb, off, msg, copied); else { - err = skb_copy_and_csum_datagram_msg(skb, 0, msg); + err = skb_copy_and_csum_datagram_msg(skb, off, msg); if (err == -EINVAL) goto csum_copy_err; @@ -1344,7 +1345,8 @@ try_again: UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite); } - goto out_free; + skb_free_datagram_locked(sk, skb); + return err; } if (!peeked) @@ -1368,9 +1370,7 @@ try_again: if (flags & MSG_TRUNC) err = ulen; -out_free: - skb_free_datagram_locked(sk, skb); -out: + __skb_free_datagram_locked(sk, skb, peeking ? -err : err); return err; csum_copy_err: |