It's required for restoring sockets in closing states:
TCP_FIN_WAIT{1,2}, TCP_WAIT_STOP, TCP_CLOSING, TCP_LAST_ACK.A fin packet is restored by sending a control message (ancillary data). In which queue a packet is restored depends on a value of tp->repair_queue. This interface is choosen, because we are goint to use sendmsg for restoring sockets in TCP_SYN_RECV states. Requests in the TCP_SYN_RECV state will be restored by sending messages in a proper listen socket. A message will contain address and a control messages with sequence numbers. Cc: "David S. Miller" <[email protected]> Cc: Alexey Kuznetsov <[email protected]> Cc: James Morris <[email protected]> Cc: Hideaki YOSHIFUJI <[email protected]> Cc: Patrick McHardy <[email protected]> Cc: Eric Dumazet <[email protected]> Cc: Pavel Emelyanov <[email protected]> Cc: Cyrill Gorcunov <[email protected]> Signed-off-by: Andrey Vagin <[email protected]> --- include/net/tcp.h | 1 + include/uapi/linux/tcp.h | 3 +++ net/ipv4/tcp.c | 40 ++++++++++++++++++++++++++++++++++++++++ net/ipv4/tcp_input.c | 2 +- 4 files changed, 45 insertions(+), 1 deletion(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 8c4dd63..4b4d9e8 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -561,6 +561,7 @@ void tcp_cwnd_application_limited(struct sock *sk); void tcp_resume_early_retransmit(struct sock *sk); void tcp_rearm_rto(struct sock *sk); void tcp_reset(struct sock *sk); +void tcp_fin(struct sock *sk); /* tcp_timer.c */ void tcp_init_xmit_timers(struct sock *); diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index 377f1e5..2cc6876 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -199,4 +199,7 @@ struct tcp_md5sig { __u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN]; /* key (binary) */ }; +/* Conntroll message types to repair tcp connections */ +#define TCP_REPAIR_SEND_FIN 1 + #endif /* _UAPI_LINUX_TCP_H */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 4cd0e87..7f5a15c 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1070,6 +1070,34 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, return err; } +static int tcp_repair_cmsg(struct sock *sk, struct msghdr *msg) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct cmsghdr *cmsg; + + for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) { + if (!CMSG_OK(msg, cmsg)) + return -EINVAL; + if (cmsg->cmsg_level != SOL_TCP) + continue; + + switch (cmsg->cmsg_type) { + case TCP_REPAIR_SEND_FIN: + if (tp->repair_queue == TCP_RECV_QUEUE) + tcp_fin(sk); + else if (tp->repair_queue == TCP_SEND_QUEUE) + tcp_shutdown(sk, SEND_SHUTDOWN); + else + return -EINVAL; + break; + default: + return -EINVAL; + } + } + + return 0; +} + int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t size) { @@ -1090,6 +1118,18 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, if (tp->repair_queue == TCP_NO_QUEUE) goto out_err; + if (msg->msg_controllen) { + if (size != 0) + return -EINVAL; + + err = tcp_repair_cmsg(sk, msg); + if (err < 0) + goto out_err; + + goto out; + } + + err = -EINVAL; if (sk->sk_state != TCP_ESTABLISHED) goto out_err; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eeaac39..352480c 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3820,7 +3820,7 @@ void tcp_reset(struct sock *sk) * * If we are in FINWAIT-2, a received FIN moves us to TIME-WAIT. */ -static void tcp_fin(struct sock *sk) +void tcp_fin(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); const struct dst_entry *dst; -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
