sockets: add helpers for creating SocketAddress from a socket

Add two helper methods that, given a socket file descriptor,
can return a populated SocketAddress struct containing either
the local or remote address information.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

include/qemu/sockets.h

@@ -88,4 +88,34 @@ int socket_dgram(SocketAddress *remote, SocketAddress *local, Error **errp);
 int parse_host_port(struct sockaddr_in *saddr, const char *str);
 int socket_init(void);
 
+/**
+ * socket_local_address:
+ * @fd: the socket file handle
+ * @errp: pointer to uninitialized error object
+ *
+ * Get the string representation of the local socket
+ * address. A pointer to the allocated address information
+ * struct will be returned, which the caller is required to
+ * release with a call qapi_free_SocketAddress when no
+ * longer required.
+ *
+ * Returns: the socket address struct, or NULL on error
+ */
+SocketAddress *socket_local_address(int fd, Error **errp);
+
+/**
+ * socket_remote_address:
+ * @fd: the socket file handle
+ * @errp: pointer to uninitialized error object
+ *
+ * Get the string representation of the remote socket
+ * address. A pointer to the allocated address information
+ * struct will be returned, which the caller is required to
+ * release with a call qapi_free_SocketAddress when no
+ * longer required.
+ *
+ * Returns: the socket address struct, or NULL on error
+ */
+SocketAddress *socket_remote_address(int fd, Error **errp);
+
 #endif /* QEMU_SOCKET_H */

util/qemu-sockets.c

@@ -1018,3 +1018,113 @@ int socket_dgram(SocketAddress *remote, SocketAddress *local, Error **errp)
     qemu_opts_del(opts);
     return fd;
 }
+
+
+static SocketAddress *
+socket_sockaddr_to_address_inet(struct sockaddr_storage *sa,
+                                socklen_t salen,
+                                Error **errp)
+{
+    char host[NI_MAXHOST];
+    char serv[NI_MAXSERV];
+    SocketAddress *addr;
+    int ret;
+
+    ret = getnameinfo((struct sockaddr *)sa, salen,
+                      host, sizeof(host),
+                      serv, sizeof(serv),
+                      NI_NUMERICHOST | NI_NUMERICSERV);
+    if (ret != 0) {
+        error_setg(errp, "Cannot format numeric socket address: %s",
+                   gai_strerror(ret));
+        return NULL;
+    }
+
+    addr = g_new0(SocketAddress, 1);
+    addr->kind = SOCKET_ADDRESS_KIND_INET;
+    addr->inet = g_new0(InetSocketAddress, 1);
+    addr->inet->host = g_strdup(host);
+    addr->inet->port = g_strdup(serv);
+    if (sa->ss_family == AF_INET) {
+        addr->inet->has_ipv4 = addr->inet->ipv4 = true;
+    } else {
+        addr->inet->has_ipv6 = addr->inet->ipv6 = true;
+    }
+
+    return addr;
+}
+
+
+#ifndef WIN32
+static SocketAddress *
+socket_sockaddr_to_address_unix(struct sockaddr_storage *sa,
+                                socklen_t salen,
+                                Error **errp)
+{
+    SocketAddress *addr;
+    struct sockaddr_un *su = (struct sockaddr_un *)sa;
+
+    addr = g_new0(SocketAddress, 1);
+    addr->kind = SOCKET_ADDRESS_KIND_UNIX;
+    addr->q_unix = g_new0(UnixSocketAddress, 1);
+    if (su->sun_path[0]) {
+        addr->q_unix->path = g_strndup(su->sun_path,
+                                       sizeof(su->sun_path));
+    }
+
+    return addr;
+}
+#endif /* WIN32 */
+
+static SocketAddress *
+socket_sockaddr_to_address(struct sockaddr_storage *sa,
+                           socklen_t salen,
+                           Error **errp)
+{
+    switch (sa->ss_family) {
+    case AF_INET:
+    case AF_INET6:
+        return socket_sockaddr_to_address_inet(sa, salen, errp);
+
+#ifndef WIN32
+    case AF_UNIX:
+        return socket_sockaddr_to_address_unix(sa, salen, errp);
+#endif /* WIN32 */
+
+    default:
+        error_setg(errp, "socket family %d unsupported",
+                   sa->ss_family);
+        return NULL;
+    }
+    return 0;
+}
+
+
+SocketAddress *socket_local_address(int fd, Error **errp)
+{
+    struct sockaddr_storage ss;
+    socklen_t sslen = sizeof(ss);
+
+    if (getsockname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
+        error_setg_errno(errp, socket_error(), "%s",
+                         "Unable to query local socket address");
+        return NULL;
+    }
+
+    return socket_sockaddr_to_address(&ss, sslen, errp);
+}
+
+
+SocketAddress *socket_remote_address(int fd, Error **errp)
+{
+    struct sockaddr_storage ss;
+    socklen_t sslen = sizeof(ss);
+
+    if (getpeername(fd, (struct sockaddr *)&ss, &sslen) < 0) {
+        error_setg_errno(errp, socket_error(), "%s",
+                         "Unable to query remote socket address");
+        return NULL;
+    }
+
+    return socket_sockaddr_to_address(&ss, sslen, errp);
+}