From: Tom Tucker <tom@opengridcomputing.com>
Subject: [RFC,PATCH] svc: REPOST - Fix the UDP address logic
Date: Tue, 23 Oct 2007 13:13:01 -0500
Message-ID: <20071023181301.11155.90411.stgit@dell3.ogc.int>
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Cc: bfields@fieldses.org, neilb@suse.de, gnb@sgi.com
To: nfs@lists.sourceforge.net
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This version of the patch sets xpt_remotelen based on the address
family returned in the sockaddr. If the address family is not
AF_INET or AF_INET6, the svc_udp_recvfrom function will
return -ENOTSUPP.
--

When the address information was moved to the svc_xprt structure, a bug
was introduced to UDP that caused an incorrect address to be used
when responding to RPC on the UDP transport. This was the result of
failing to completely implement the generic address logic for the UDP 
transport.

Thanks to Greg for pointing this out...

Since I confused myself, it's probably a good idea to describe how 
this is supposed to work. The transport is responsible for setting 
the xpt_local and xpt_remote addresses in the svc_xprt structure as
part of xpo_recvfrom processing. This cannot be done in a generic way 
and in fact varies between TCP, UDP and RDMA. A set of xpo_ functions
(e.g. getlocalname, getremotename) could have been added but this would
have resulted in additional caching and copying of the addresses around. 

The generic svc_recv code copies the addresses from the svc_xprt 
structure into the rqstp structure as part of svc_recv processing.  

The xpt_local address should also be set on listening endpoints, for
tcp/rdma this is done as part of endpoint creation and for new 
connections in xpo_accept processing. 

This patch was tested with Connectathon over V3 on UDP.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
---

 net/sunrpc/svcsock.c |   31 +++++++++++++++++++++++++------
 1 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index e1a27ee..8924cad 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -140,6 +140,18 @@ static char *__svc_print_addr(struct soc
 	return buf;
 }
 
+static size_t svc_sockaddr_len(struct sockaddr *addr)
+{
+	switch (addr->sa_family) {
+	case AF_INET:
+		return sizeof(struct sockaddr_in);
+	case AF_INET6:
+		return sizeof(struct sockaddr_in6);
+	}
+	dprintk("svc: unrecognized address family %d\n", addr->sa_family);
+	return -ENOTSUPP;
+}
+
 /**
  * svc_print_addr - Format rq_addr field for printing
  * @rqstp: svc_rqst struct containing address to print
@@ -473,17 +485,21 @@ svc_write_space(struct sock *sk)
 static inline void svc_udp_get_dest_address(struct svc_rqst *rqstp,
 					    struct cmsghdr *cmh)
 {
-	struct svc_sock *svsk =
-		container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
+	struct svc_xprt *xprt = rqstp->rq_xprt;
+	struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
 	switch (svsk->sk_sk->sk_family) {
 	case AF_INET: {
 		struct in_pktinfo *pki = CMSG_DATA(cmh);
-		rqstp->rq_daddr.addr.s_addr = pki->ipi_spec_dst.s_addr;
+		struct sockaddr_in *sin =
+			(struct sockaddr_in *)&xprt->xpt_local;
+		sin->sin_addr.s_addr = pki->ipi_spec_dst.s_addr;
 		break;
 		}
 	case AF_INET6: {
 		struct in6_pktinfo *pki = CMSG_DATA(cmh);
-		ipv6_addr_copy(&rqstp->rq_daddr.addr6, &pki->ipi6_addr);
+		struct sockaddr_in6 *sin6 =
+			(struct sockaddr_in6 *)&xprt->xpt_local;
+		ipv6_addr_copy(&sin6->sin6_addr, &pki->ipi6_addr);
 		break;
 		}
 	}
@@ -506,7 +522,7 @@ svc_udp_recvfrom(struct svc_rqst *rqstp)
 	struct cmsghdr *cmh = &buffer.hdr;
 	int		err, len;
 	struct msghdr msg = {
-		.msg_name = svc_addr(rqstp),
+		.msg_name = &svsk->sk_xprt.xpt_remote,
 		.msg_control = cmh,
 		.msg_controllen = sizeof(buffer),
 		.msg_flags = MSG_DONTWAIT,
@@ -541,7 +557,10 @@ svc_udp_recvfrom(struct svc_rqst *rqstp)
 		svc_xprt_received(&svsk->sk_xprt);
 		return -EAGAIN;
 	}
-	rqstp->rq_addrlen = sizeof(rqstp->rq_addr);
+	len = svc_sockaddr_len((struct sockaddr *)&svsk->sk_xprt.xpt_remote);
+	if (len < 0)
+		return len;
+	svsk->sk_xprt.xpt_remotelen = len;
 	if (skb->tstamp.tv64 == 0) {
 		skb->tstamp = ktime_get_real();
 		/* Don't enable netstamp, sunrpc doesn't

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