3 files changed, 62 insertions, 36 deletions

diff --git a/contrib/bsnmp/lib/bsnmpclient.3 b/contrib/bsnmp/lib/bsnmpclient.3
index 0a2286eb14c4..1a5aa2e5e3a6 100644
--- a/contrib/bsnmp/lib/bsnmpclient.3
+++ b/contrib/bsnmp/lib/bsnmpclient.3
@@ -31,7 +31,7 @@
 .\"
 .\" $Begemot: bsnmp/lib/bsnmpclient.3,v 1.12 2005/10/04 08:46:50 brandt_h Exp $
 .\"
-.Dd March 31, 2020
+.Dd June 24, 2025
 .Dt BSNMPCLIENT 3
 .Os
 .Sh NAME
@@ -155,7 +155,7 @@ struct snmp_client {
 	snmp_timeout_start_f	timeout_start;
 	snmp_timeout_stop_f	timeout_stop;
 
-	char			local_path[sizeof(SNMP_LOCAL_PATH)];
+	char			local_path[SUNPATHLEN];
 };
 .Ed
 .Pp
@@ -285,8 +285,19 @@ The function will be called with the return value of the corresponding
 .Fn timeout_start
 function.
 .It Va local_path
-If in local socket mode, the name of the clients socket.
-Not needed by the application.
+In local socket mode, optional path name the client socket shall be bound to
+before connecting to the server.
+For
+.Dv SOCK_STREAM
+local socket the named path is optional, and library will skip
+.Xr bind 2
+if path is not provided.
+For
+.Dv SOCK_DGRAM
+local socket the named path is required, thus library will create a random
+one in
+.Pa /tmp
+if path is not provided.
 .El
 .Pp
 In the current implementation there is a global variable
diff --git a/contrib/bsnmp/lib/snmpclient.c b/contrib/bsnmp/lib/snmpclient.c
index d5d4af998a0c..5fa7d4f5be2a 100644
--- a/contrib/bsnmp/lib/snmpclient.c
+++ b/contrib/bsnmp/lib/snmpclient.c
@@ -977,7 +977,10 @@ remove_local(void)
 static int
 open_client_local(const char *path)
 {
-	struct sockaddr_un sa;
+	struct sockaddr_un sa = {
+		.sun_family = AF_LOCAL,
+		.sun_len = sizeof(sa),
+	};
 	char *ptr;
 	int stype;
 
@@ -1003,43 +1006,56 @@ open_client_local(const char *path)
 		return (-1);
 	}
 
-	snprintf(snmp_client.local_path, sizeof(snmp_client.local_path),
-	    "%s", SNMP_LOCAL_PATH);
-
-	if (mktemp(snmp_client.local_path) == NULL) {
-		seterr(&snmp_client, "%s", strerror(errno));
-		(void)close(snmp_client.fd);
-		snmp_client.fd = -1;
-		return (-1);
+	/*
+	 * A datagram socket requires a name to receive replies back.  Would
+	 * be cool to have an extension to unix(4) sockets similar to ip(4)
+	 * IP_RECVDSTADDR/IP_SENDSRCADDR, so that a one-to-many datagram
+	 * UNIX socket can send replies to its anonymous peers.
+	 */
+	if (snmp_client.trans == SNMP_TRANS_LOC_DGRAM &&
+	    snmp_client.local_path[0] == '\0') {
+		(void)strlcpy(snmp_client.local_path, "/tmp/snmpXXXXXXXXXXXXXX",
+		    sizeof(snmp_client.local_path));
+		if (mktemp(snmp_client.local_path) == NULL) {
+			seterr(&snmp_client, "mktemp(3): %s", strerror(errno));
+			goto fail;
+		}
 	}
 
-	sa.sun_family = AF_LOCAL;
-	sa.sun_len = sizeof(sa);
-	strcpy(sa.sun_path, snmp_client.local_path);
-
-	if (bind(snmp_client.fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
-		seterr(&snmp_client, "%s", strerror(errno));
-		(void)close(snmp_client.fd);
-		snmp_client.fd = -1;
-		(void)remove(snmp_client.local_path);
-		return (-1);
+	if (snmp_client.local_path[0] != '\0') {
+		if (strlcpy(sa.sun_path, snmp_client.local_path,
+		    sizeof(sa.sun_path)) >=
+		    sizeof(sa.sun_path)) {
+			seterr(&snmp_client, "%s",
+			    "Local socket pathname too long");
+			goto fail;
+		}
+		if (bind(snmp_client.fd, (struct sockaddr *)&sa, sizeof(sa)) ==
+		    -1) {
+			seterr(&snmp_client, "%s", strerror(errno));
+			goto fail;
+		}
+		atexit(remove_local);
 	}
-	atexit(remove_local);
 
-	sa.sun_family = AF_LOCAL;
-	sa.sun_len = offsetof(struct sockaddr_un, sun_path) +
-	    strlen(snmp_client.chost);
-	strncpy(sa.sun_path, snmp_client.chost, sizeof(sa.sun_path) - 1);
-	sa.sun_path[sizeof(sa.sun_path) - 1] = '\0';
+	if (strlcpy(sa.sun_path, snmp_client.chost, sizeof(sa.sun_path)) >=
+	    sizeof(sa.sun_path)) {
+		seterr(&snmp_client, "%s", "Server socket pathname too long");
+		goto fail;
+	}
 
 	if (connect(snmp_client.fd, (struct sockaddr *)&sa, sa.sun_len) == -1) {
 		seterr(&snmp_client, "%s", strerror(errno));
-		(void)close(snmp_client.fd);
-		snmp_client.fd = -1;
-		(void)remove(snmp_client.local_path);
-		return (-1);
+		goto fail;
 	}
 	return (0);
+
+fail:
+	(void)close(snmp_client.fd);
+	snmp_client.fd = -1;
+	if (snmp_client.local_path[0] != '\0')
+		(void)remove(snmp_client.local_path);
+	return (-1);
 }
 
 /*
diff --git a/contrib/bsnmp/lib/snmpclient.h b/contrib/bsnmp/lib/snmpclient.h
index 662dc7c4a204..a8a79ff824bc 100644
--- a/contrib/bsnmp/lib/snmpclient.h
+++ b/contrib/bsnmp/lib/snmpclient.h
@@ -35,6 +35,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/time.h>
+#include <sys/un.h>
 #include <netinet/in.h>
 #include <stddef.h>
 
@@ -42,8 +43,6 @@
 #define SNMP_STRERROR_LEN 200
 #define	SNMP_DEFAULT_LOCAL "/var/run/snmpd.sock"
 
-#define SNMP_LOCAL_PATH	"/tmp/snmpXXXXXXXXXXXXXX"
-
 /*
  * transport methods
  */
@@ -111,7 +110,7 @@ struct snmp_client {
 	snmp_timeout_start_f	timeout_start;
 	snmp_timeout_stop_f	timeout_stop;
 
-	char			local_path[sizeof(SNMP_LOCAL_PATH)];
+	char			local_path[SUNPATHLEN];
 };
 
 /* the global context */