Polish VTCP usage in the acceptor setup

This adds the errno value to error logs for TCP fast open and accept
filters. For FreeBSD errno is cleared prior to calling setsockopt with
the hope that it will help understand if it's actually failing with an
undocumented ENOENT.

Speaking of documentation, the return value is either 0 or -1 for so
there's no point in logging that.

bin/varnishd/cache/cache_acceptor.c

@@ -623,14 +623,11 @@ ccf_start(struct cli *cli, const char * const *av, void *priv)
 	VTAILQ_FOREACH(ls, &heritage.socks, list) {
 		CHECK_OBJ_NOTNULL(ls->transport, TRANSPORT_MAGIC);
 		assert (ls->sock > 0);	// We know where stdin is
-		if (cache_param->tcp_fastopen) {
-			int i;
-			i = VTCP_fastopen(ls->sock, cache_param->listen_depth);
-			if (i)
-				VSL(SLT_Error, 0,
-				    "Kernel TCP Fast Open: sock=%d, ret=%d %s",
-				    ls->sock, i, vstrerror(errno));
-		}
+		if (cache_param->tcp_fastopen &&
+		    VTCP_fastopen(ls->sock, cache_param->listen_depth))
+			VSL(SLT_Error, 0,
+			    "Kernel TCP Fast Open: sock=%d, errno=%d %s",
+			    ls->sock, errno, vstrerror(errno));
 		if (listen(ls->sock, cache_param->listen_depth)) {
 			VCLI_SetResult(cli, CLIS_CANT);
 			VCLI_Out(cli, "Listen failed on socket '%s': %s",
@@ -638,14 +635,10 @@ ccf_start(struct cli *cli, const char * const *av, void *priv)
 			return;
 		}
 		vca_tcp_opt_set(ls->sock, ls->uds, 1);
-		if (cache_param->accept_filter) {
-			int i;
-			i = VTCP_filter_http(ls->sock);
-			if (i)
-				VSL(SLT_Error, 0,
-				    "Kernel filtering: sock=%d, ret=%d %s",
-				    ls->sock, i, vstrerror(errno));
-		}
+		if (cache_param->accept_filter && VTCP_filter_http(ls->sock))
+			VSL(SLT_Error, 0,
+			    "Kernel filtering: sock=%d, errno=%d %s",
+			    ls->sock, errno, vstrerror(errno));
 	}
 
 	need_test = 1;

lib/libvarnish/vtcp.c

@@ -151,10 +151,11 @@ VTCP_filter_http(int sock)
 	int retval;
 	struct accept_filter_arg afa;
 
-	memset(&afa, 0, sizeof(afa));
-	strcpy(afa.af_name, "httpready");
+	memset(&afa, 0, sizeof afa);
+	bprintf(afa.af_name, "httpready");
+	errno = 0;
 	retval = setsockopt(sock, SOL_SOCKET, SO_ACCEPTFILTER,
-	    &afa, sizeof afa );
+	    &afa, sizeof afa);
 	return (retval);
 }
 
@@ -166,7 +167,7 @@ VTCP_filter_http(int sock)
 	int retval;
 	int defer = 1;
 
-	retval = setsockopt(sock, SOL_TCP,TCP_DEFER_ACCEPT,
+	retval = setsockopt(sock, SOL_TCP, TCP_DEFER_ACCEPT,
 	    &defer, sizeof defer);
 	return (retval);
 }