Make UDP sockets not blocking

[nfs-utils.git] / support / nfs / svc_socket.c

diff --git a/support/nfs/svc_socket.c b/support/nfs/svc_socket.c
index 888c915931b000f42d86d026bc94e86ed8329139..33076009ac0538de8569fd3489282bbeb2d672ed 100644 (file)
--- a/support/nfs/svc_socket.c
+++ b/support/nfs/svc_socket.c
@@ -42,7 +42,7 @@ svc_socket (u_long number, int type, int protocol, int reuse)
   socklen_t len = sizeof (struct sockaddr_in);
   char rpcdata [1024], servdata [1024];
   struct rpcent rpcbuf, *rpcp;
-  struct servent servbuf, *servp;
+  struct servent servbuf, *servp = NULL;
   int sock, ret;
   const char *proto = protocol == IPPROTO_TCP ? "tcp" : "udp";
 
@@ -64,7 +64,7 @@ svc_socket (u_long number, int type, int protocol, int reuse)
        }
     }
 
-  __bzero ((char *) &addr, sizeof (addr));
+  memset (&addr, 0, sizeof (addr));
   addr.sin_family = AF_INET;
 
   ret = getrpcbynumber_r (number, &rpcbuf, rpcdata, sizeof rpcdata,
@@ -113,11 +113,22 @@ svc_socket (u_long number, int type, int protocol, int reuse)
        }
     }
 
-  if (sock >= 0 && protocol == IPPROTO_TCP)
+  if (sock >= 0)
     {
-       /* Make the TCP rendezvous socket non-block to avoid
-        * problems with blocking in accept() after a spurious
-        * wakeup from the kernel */
+           /* This socket might be shared among multiple processes
+            * if mountd is run multi-threaded.  So it is safest to
+            * make it non-blocking, else all threads might wake
+            * one will get the data, and the others will block
+            * indefinitely.
+            * In all cases, transaction on this socket are atomic
+            * (accept for TCP, packet-read and packet-write for UDP)
+            * so O_NONBLOCK will not confuse unprepared code causing
+            * it to corrupt messages.
+            * It generally safest to have O_NONBLOCK when doing an accept
+            * as if we get a RST after the SYN and before accept runs,
+            * we can block despite being told there was an acceptable
+            * connection.
+            */
        int flags;
        if ((flags = fcntl(sock, F_GETFL)) < 0)
          {