Merge remote-tracking branch 'remotes/berrange/tags/pull-sockets-2017-07-11-3' into staging

Merge sockets 2017/07/11 v3

# gpg: Signature made Fri 14 Jul 2017 16:09:03 BST
# gpg:                using RSA key 0xBE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>"
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange/tags/pull-sockets-2017-07-11-3:
  io: preserve ipv4/ipv6 flags when resolving InetSocketAddress
  sockets: ensure we don't accept IPv4 clients when IPv4 is disabled
  sockets: don't block IPv4 clients when listening on "::"
  sockets: ensure we can bind to both ipv4 & ipv6 separately

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 56 insertions, 21 deletions

diff --git a/io/dns-resolver.c b/io/dns-resolver.c
index 57a8896cbb..c072d121c3 100644
--- a/io/dns-resolver.c
+++ b/io/dns-resolver.c
@@ -116,8 +116,10 @@ static int qio_dns_resolver_lookup_sync_inet(QIODNSResolver *resolver,
             .numeric = true,
             .has_to = iaddr->has_to,
             .to = iaddr->to,
-            .has_ipv4 = false,
-            .has_ipv6 = false,
+            .has_ipv4 = iaddr->has_ipv4,
+            .ipv4 = iaddr->ipv4,
+            .has_ipv6 = iaddr->has_ipv6,
+            .ipv6 = iaddr->ipv6,
         };
 
         (*addrs)[i] = newaddr;
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index 55b6c17f5f..1358c81bcc 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -104,17 +104,16 @@ NetworkAddressFamily inet_netfamily(int family)
  *   f     t       PF_INET6
  *   t     -       PF_INET
  *   t     f       PF_INET
- *   t     t       PF_INET6
+ *   t     t       PF_INET6/PF_UNSPEC
  *
  * NB, this matrix is only about getting the necessary results
  * from getaddrinfo(). Some of the cases require further work
  * after reading results from getaddrinfo in order to fully
- * apply the logic the end user wants. eg with the last case
- * ipv4=t + ipv6=t + PF_INET6, getaddrinfo alone can only
- * guarantee the ipv6=t part of the request - we need more
- * checks to provide ipv4=t part of the guarantee. This is
- * outside scope of this method and not currently handled by
- * callers at all.
+ * apply the logic the end user wants.
+ *
+ * In the first and last cases, we must set IPV6_V6ONLY=0
+ * when binding, to allow a single listener to potentially
+ * accept both IPv4+6 addresses.
  */
 int inet_ai_family_from_address(InetSocketAddress *addr,
                                 Error **errp)
@@ -124,6 +123,23 @@ int inet_ai_family_from_address(InetSocketAddress *addr,
         error_setg(errp, "Cannot disable IPv4 and IPv6 at same time");
         return PF_UNSPEC;
     }
+    if ((addr->has_ipv6 && addr->ipv6) && (addr->has_ipv4 && addr->ipv4)) {
+        /*
+         * Some backends can only do a single listener. In that case
+         * we want empty hostname to resolve to "::" and then use the
+         * flag IPV6_V6ONLY==0 to get both protocols on 1 socket. This
+         * doesn't work for addresses other than "", so they're just
+         * inevitably broken until multiple listeners can be used,
+         * and thus we honour getaddrinfo automatic protocol detection
+         * Once all backends do multi-listener, remove the PF_INET6
+         * branch entirely.
+         */
+        if (!addr->host || g_str_equal(addr->host, "")) {
+            return PF_INET6;
+        } else {
+            return PF_UNSPEC;
+        }
+    }
     if ((addr->has_ipv6 && addr->ipv6) || (addr->has_ipv4 && !addr->ipv4)) {
         return PF_INET6;
     }
@@ -208,22 +224,43 @@ static int inet_listen_saddr(InetSocketAddress *saddr,
         }
 
         socket_set_fast_reuse(slisten);
-#ifdef IPV6_V6ONLY
-        if (e->ai_family == PF_INET6) {
-            /* listen on both ipv4 and ipv6 */
-            const int off = 0;
-            qemu_setsockopt(slisten, IPPROTO_IPV6, IPV6_V6ONLY, &off,
-                            sizeof(off));
-        }
-#endif
 
         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) {
                 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");
@@ -603,16 +640,12 @@ int inet_parse(InetSocketAddress *addr, const char *str, Error **errp)
             error_setg(errp, "error parsing IPv6 address '%s'", str);
             return -1;
         }
-        addr->ipv6 = addr->has_ipv6 = true;
     } else {
         /* hostname or IPv4 addr */
         if (sscanf(str, "%64[^:]:%32[^,]%n", host, port, &pos) != 2) {
             error_setg(errp, "error parsing address '%s'", str);
             return -1;
         }
-        if (host[strspn(host, "0123456789.")] == '\0') {
-            addr->ipv4 = addr->has_ipv4 = true;
-        }
     }
 
     addr->host = g_strdup(host);