sockets: factor out a new try_bind() function

A refactoring step to prepare for the problem
exposed by the test-listen test in the previous commit.

Simplify and reorganize the IPv6 specific extra
measures and move it out of the for loop to increase
code readability. No semantic changes.

Signed-off-by: Knut Omang <knut.omang@oracle.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

1 files changed, 39 insertions, 30 deletions

diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index d149383bb9..211ebadcec 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -149,6 +149,44 @@ int inet_ai_family_from_address(InetSocketAddress *addr,
     return PF_UNSPEC;
 }
 
+static int try_bind(int socket, InetSocketAddress *saddr, struct addrinfo *e)
+{
+#ifndef IPV6_V6ONLY
+    return bind(socket, e->ai_addr, e->ai_addrlen);
+#else
+    /*
+     * Deals with first & last cases in matrix in comment
+     * for inet_ai_family_from_address().
+     */
+    int v6only =
+        ((!saddr->has_ipv4 && !saddr->has_ipv6) ||
+         (saddr->has_ipv4 && saddr->ipv4 &&
+          saddr->has_ipv6 && saddr->ipv6)) ? 0 : 1;
+    int stat;
+
+ rebind:
+    if (e->ai_family == PF_INET6) {
+        qemu_setsockopt(socket, IPPROTO_IPV6, IPV6_V6ONLY, &v6only,
+                        sizeof(v6only));
+    }
+
+    stat = bind(socket, e->ai_addr, e->ai_addrlen);
+    if (!stat) {
+        return 0;
+    }
+
+    /* If we got EADDRINUSE from an IPv6 bind & v6only is unset,
+     * it could be that the IPv4 port is already claimed, so retry
+     * with v6only set
+     */
+    if (e->ai_family == PF_INET6 && errno == EADDRINUSE && !v6only) {
+        v6only = 1;
+        goto rebind;
+    }
+    return stat;
+#endif
+}
+
 static int inet_listen_saddr(InetSocketAddress *saddr,
                              int port_offset,
                              bool update_addr,
@@ -228,39 +266,10 @@ static int inet_listen_saddr(InetSocketAddress *saddr,
         port_min = inet_getport(e);
         port_max = saddr->has_to ? saddr->to + port_offset : port_min;
         for (p = port_min; p <= port_max; p++) {
-#ifdef IPV6_V6ONLY
-            /*
-             * Deals with first & last cases in matrix in comment
-             * for inet_ai_family_from_address().
-             */
-            int v6only =
-                ((!saddr->has_ipv4 && !saddr->has_ipv6) ||
-                 (saddr->has_ipv4 && saddr->ipv4 &&
-                  saddr->has_ipv6 && saddr->ipv6)) ? 0 : 1;
-#endif
             inet_setport(e, p);
-#ifdef IPV6_V6ONLY
-        rebind:
-            if (e->ai_family == PF_INET6) {
-                qemu_setsockopt(slisten, IPPROTO_IPV6, IPV6_V6ONLY, &v6only,
-                                sizeof(v6only));
-            }
-#endif
-            if (bind(slisten, e->ai_addr, e->ai_addrlen) == 0) {
+            if (try_bind(slisten, saddr, e) >= 0) {
                 goto listen;
             }
-
-#ifdef IPV6_V6ONLY
-            /* If we got EADDRINUSE from an IPv6 bind & V6ONLY is unset,
-             * it could be that the IPv4 port is already claimed, so retry
-             * with V6ONLY set
-             */
-            if (e->ai_family == PF_INET6 && errno == EADDRINUSE && !v6only) {
-                v6only = 1;
-                goto rebind;
-            }
-#endif
-
             if (p == port_max) {
                 if (!e->ai_next) {
                     error_setg_errno(errp, errno, "Failed to bind socket");