[master] 1e1493bdc Refactor: Centralize (struct sockaddr_un) initialization

[Nils Goroll]

commit 1e1493bdc7ba4f8ef6dba35281fb2b18c688423c
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Mon Nov 14 16:45:22 2022 +0100

    Refactor: Centralize (struct sockaddr_un) initialization
    
    We had three call sites, one with and two without size checking.
    
    Other improvements:
    
    - zero (struct sockaddr_un).sun_path
    - set errno if the path argument does not fit
    
    Motivated by: #3863

diff --git a/bin/varnishd/mgt/mgt_acceptor.c b/bin/varnishd/mgt/mgt_acceptor.c
index 612198672..9cbeb81aa 100644
--- a/bin/varnishd/mgt/mgt_acceptor.c
+++ b/bin/varnishd/mgt/mgt_acceptor.c
@@ -76,11 +76,17 @@ struct uds_perms {
 static VTAILQ_HEAD(,listen_arg) listen_args =
     VTAILQ_HEAD_INITIALIZER(listen_args);
 
+static int
+mac_vus_bind(void *priv, const struct sockaddr_un *uds)
+{
+	return (VUS_bind(uds, priv));
+}
+
 static int
 mac_opensocket(struct listen_sock *ls)
 {
 	int fail;
-	struct sockaddr_un uds;
+	const char *err;
 
 	CHECK_OBJ_NOTNULL(ls, LISTEN_SOCK_MAGIC);
 	if (ls->sock > 0) {
@@ -89,11 +95,8 @@ mac_opensocket(struct listen_sock *ls)
 	}
 	if (!ls->uds)
 		ls->sock = VTCP_bind(ls->addr, NULL);
-	else {
-		uds.sun_family = PF_UNIX;
-		bprintf(uds.sun_path, "%s", ls->endpoint);
-		ls->sock = VUS_bind(&uds, NULL);
-	}
+	else
+		ls->sock = VUS_resolver(ls->endpoint, mac_vus_bind, NULL, &err);
 	fail = errno;
 	if (ls->sock < 0) {
 		AN(fail);
diff --git a/lib/libvarnish/vus.c b/lib/libvarnish/vus.c
index ba803b08d..0f39fb601 100644
--- a/lib/libvarnish/vus.c
+++ b/lib/libvarnish/vus.c
@@ -41,24 +41,41 @@
 #include "vus.h"
 #include "vtcp.h"
 
+static int
+sun_init(struct sockaddr_un *uds, const char *path, const char **err)
+{
+	AN(uds);
+	AN(path);
+	assert(*path == '/');
+
+	if (err)
+		*err = NULL;
+
+	if (strlen(path) + 1 > sizeof(uds->sun_path)) {
+		errno = ENAMETOOLONG;
+		if (err)
+			*err = "Path too long for a Unix domain socket";
+		return (-1);
+	}
+	memset(uds->sun_path, 0, sizeof(uds->sun_path));
+	bprintf(uds->sun_path, "%s", path);
+	uds->sun_family = PF_UNIX;
+	return (0);
+}
+
 int
 VUS_resolver(const char *path, vus_resolved_f *func, void *priv,
 	     const char **err)
 {
 	struct sockaddr_un uds;
-	int ret = 0;
-
-	AN(path);
-	assert(*path == '/');
+	int ret;
 
 	AN(err);
-	*err = NULL;
-	if (strlen(path) + 1 > sizeof(uds.sun_path)) {
-		*err = "Path too long for a Unix domain socket";
-		return (-1);
-	}
-	bprintf(uds.sun_path, "%s", path);
-	uds.sun_family = PF_UNIX;
+
+	ret = sun_init(&uds, path, err);
+	if (ret)
+		return (ret);
+
 	if (func != NULL)
 		ret = func(priv, &uds);
 	return (ret);
@@ -110,8 +127,9 @@ VUS_connect(const char *path, int msec)
 
 	if (path == NULL)
 		return (-1);
-	uds.sun_family = PF_UNIX;
-	bprintf(uds.sun_path, "%s", path);
+	i = sun_init(&uds, path, NULL);
+	if (i)
+		return (i);
 	AN(sl);
 
 	s = socket(PF_UNIX, SOCK_STREAM, 0);