From: James Morris <[EMAIL PROTECTED]> Date: Thu, 1 Feb 2007 18:44:48 -0500 (EST)
> A quick & dirty solution, which is what I think the BSD kernels do, is to > still drop the packet but just not return an error to the app. The app > then just sees a slight delay on the initial connection, as if a DNS > lookup took a bit longer than usual. I have another idea. Why don't we just flat-out ignore MSG_DONTWAIT for the socket visible cases, and handle connect() similarly? I think this is (just barely) legal, will be simple to implement, and will leave us with semantics that look like: 1) Sockets never see -EAGAIN due to SA resolution. They'll just pause until the route is resolved, even with O_NONBLOCK or MSG_DONTWAIT. 2) Asynchronous contexts such as ICMP replies and firewalling will still see the -EAGAIN and simply drop packets. These sleeps are legal because all of the socket paths involved have to be able to do lock_socket() (at a minimum) anyways. Something like this (untested) on the ipv4 side, for example: diff --git a/include/net/route.h b/include/net/route.h index 486e37a..a8af632 100644 --- a/include/net/route.h +++ b/include/net/route.h @@ -146,7 +146,8 @@ static inline char rt_tos2priority(u8 tos) static inline int ip_route_connect(struct rtable **rp, __be32 dst, __be32 src, u32 tos, int oif, u8 protocol, - __be16 sport, __be16 dport, struct sock *sk) + __be16 sport, __be16 dport, struct sock *sk, + int flags) { struct flowi fl = { .oif = oif, .nl_u = { .ip4_u = { .daddr = dst, @@ -168,7 +169,7 @@ static inline int ip_route_connect(struct rtable **rp, __be32 dst, *rp = NULL; } security_sk_classify_flow(sk, &fl); - return ip_route_output_flow(rp, &fl, sk, 0); + return ip_route_output_flow(rp, &fl, sk, 1); } static inline int ip_route_newports(struct rtable **rp, u8 protocol, diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index 90c74b4..fa2c982 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -72,7 +72,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) tmp = ip_route_connect(&rt, nexthop, inet->saddr, RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, IPPROTO_DCCP, - inet->sport, usin->sin_port, sk); + inet->sport, usin->sin_port, sk, 1); if (tmp < 0) return tmp; diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 8640096..5750a2b 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1007,7 +1007,7 @@ static int inet_sk_reselect_saddr(struct sock *sk) RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, sk->sk_protocol, - inet->sport, inet->dport, sk); + inet->sport, inet->dport, sk, 0); if (err) return err; diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c index 7b068a8..0072d79 100644 --- a/net/ipv4/datagram.c +++ b/net/ipv4/datagram.c @@ -49,7 +49,7 @@ int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) err = ip_route_connect(&rt, usin->sin_addr.s_addr, saddr, RT_CONN_FLAGS(sk), oif, sk->sk_protocol, - inet->sport, usin->sin_port, sk); + inet->sport, usin->sin_port, sk, 1); if (err) return err; if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) { diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c index a6c63bb..fed6a1e 100644 --- a/net/ipv4/raw.c +++ b/net/ipv4/raw.c @@ -489,7 +489,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, } security_sk_classify_flow(sk, &fl); - err = ip_route_output_flow(&rt, &fl, sk, !(msg->msg_flags&MSG_DONTWAIT)); + err = ip_route_output_flow(&rt, &fl, sk, 1); } if (err) goto done; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index f061ec5..383e4b5 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -191,7 +191,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) tmp = ip_route_connect(&rt, nexthop, inet->saddr, RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, IPPROTO_TCP, - inet->sport, usin->sin_port, sk); + inet->sport, usin->sin_port, sk, 1); if (tmp < 0) return tmp; diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index cfff930..8b54c68 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -629,7 +629,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, { .sport = inet->sport, .dport = dport } } }; security_sk_classify_flow(sk, &fl); - err = ip_route_output_flow(&rt, &fl, sk, !(msg->msg_flags&MSG_DONTWAIT)); + err = ip_route_output_flow(&rt, &fl, sk, 1); if (err) goto out; - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html