improve socket error reporting

always use getsockopt() to query the meaning of POLLERR, rather than
reporting "Unidentified socket error".
this is unlikely to have any effect when using select(), as that one
pretty much never signals exceptional conditions.

src/socket.c

@@ -297,7 +297,7 @@ static void start_tls_p3( conn_t *conn, int ok )
 static void socket_fd_cb( int, void * );
 
 static void socket_connect_failed( conn_t * );
-static void socket_connected2( conn_t * );
+static void socket_connected( conn_t * );
 static void socket_connect_bail( conn_t * );
 
 static void
@@ -388,7 +388,7 @@ socket_connect( conn_t *sock, void (*cb)( int ok, void *aux ) )
 
 	}
 	info( "\vok\n" );
-	socket_connected2( sock );
+	socket_connected( sock );
 	return;
 }
 
@@ -402,24 +402,6 @@ socket_connect_failed( conn_t *conn )
 
 static void
 socket_connected( conn_t *conn )
-{
-	int soerr;
-	socklen_t selen = sizeof(soerr);
-
-	if (getsockopt( conn->fd, SOL_SOCKET, SO_ERROR, &soerr, &selen )) {
-		perror( "getsockopt" );
-		exit( 1 );
-	}
-	if (soerr) {
-		errno = soerr;
-		socket_connect_failed( conn );
-		return;
-	}
-	socket_connected2( conn );
-}
-
-static void
-socket_connected2( conn_t *conn )
 {
 	conf_fd( conn->fd, 0, POLLIN );
 	conn->state = SCK_READY;
@@ -637,13 +619,22 @@ socket_fd_cb( int events, void *aux )
 {
 	conn_t *conn = (conn_t *)aux;
 
+	if ((events & POLLERR) || conn->state == SCK_CONNECTING) {
+		int soerr;
+		socklen_t selen = sizeof(soerr);
+		if (getsockopt( conn->fd, SOL_SOCKET, SO_ERROR, &soerr, &selen )) {
+			perror( "getsockopt" );
+			exit( 1 );
+		}
+		errno = soerr;
 		if (conn->state == SCK_CONNECTING) {
+			if (errno)
+				socket_connect_failed( conn );
+			else
 				socket_connected( conn );
 			return;
 		}
-
-	if (events & POLLERR) {
-		error( "Unidentified socket error from %s.\n", conn->name );
+		sys_error( "Socket error from %s", conn->name );
 		socket_fail( conn );
 		return;
 	}