git: 80586e853674 - main - libsysdecode: decode Generic Netlink controller messages

The branch main has been updated by kp:

URL: https://cgit.FreeBSD.org/src/commit/?id=80586e853674c6d63888379274accea5c82407f2

commit 80586e853674c6d63888379274accea5c82407f2
Author:     Ishan Agrawal <iagrawal9990@gmail.com>
AuthorDate: 2026-06-29 05:17:14 +0000
Commit:     Kristof Provost <kp@FreeBSD.org>
CommitDate: 2026-07-05 14:03:34 +0000

    libsysdecode: decode Generic Netlink controller messages
    
    Decode Generic Netlink controller (GENL_ID_CTRL) messages in
    Netlink payloads. Display the Generic Netlink header along with
    the CTRL_CMD_GETFAMILY attributes, including the family ID and
    family name.
    
    Signed-off-by:  Ishan Agrawal <iagrawal9990@gmail.com>
    Reviewed by:    kp
    Sponsored-by:   Google LLC (GSoC 2026)
---
 lib/libsysdecode/netlink.c | 70 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 60 insertions(+), 10 deletions(-)

diff --git a/lib/libsysdecode/netlink.c b/lib/libsysdecode/netlink.c
index 723272d3b8da..4dbe6c087dcf 100644
--- a/lib/libsysdecode/netlink.c
+++ b/lib/libsysdecode/netlink.c
@@ -6,6 +6,8 @@
 
 #include <sys/param.h>
 #include <netlink/netlink.h>
+#include <netlink/netlink_generic.h>
+#include <netlink/netlink_snl.h>
 
 #include <stdio.h>
 #include <stdbool.h>
@@ -20,6 +22,7 @@
  * Returns false if the data is malformed, allowing the caller
  * to fallback to a standard hex/string dump.
  */
+
 bool
 sysdecode_netlink(FILE *fp, const void *buf, size_t len, int protocol)
 {
@@ -51,7 +54,16 @@ sysdecode_netlink(FILE *fp, const void *buf, size_t len, int protocol)
 			break;
 		}
 
-		fprintf(fp, "len=%u,type=", nl->nlmsg_len);
+		fprintf(fp, "flags=");
+		const char *nlm_f = sysdecode_nlm_flag(nl->nlmsg_flags);
+		if (nlm_f != NULL)
+			fprintf(fp, "%s", nlm_f);
+		else
+			fprintf(fp, "0x%x", nl->nlmsg_flags);
+
+		fprintf(fp, ",seq=%u,pid=%u", nl->nlmsg_seq, nl->nlmsg_pid);
+
+		fprintf(fp, ",len=%u,type=", nl->nlmsg_len);
 
 		/* Decode Standard Message Types. */
 		switch (nl->nlmsg_type) {
@@ -67,20 +79,58 @@ sysdecode_netlink(FILE *fp, const void *buf, size_t len, int protocol)
 		case NLMSG_OVERRUN:
 			fprintf(fp, "NLMSG_OVERRUN");
 			break;
+		case GENL_ID_CTRL:
+			if (protocol != NETLINK_GENERIC)
+				break;
+
+			fprintf(fp, "GENL_ID_CTRL");
+
+			const struct genlmsghdr *genl =
+			    (const struct genlmsghdr *)(const void *)
+			    ((const char *)nl + sizeof(struct nlmsghdr));
+
+			uint16_t family_id = 0;
+			const char *family_name = NULL;
+
+			fprintf(fp,
+			    ",genl={cmd=%u,"
+			    "ver=%u,reserve=%u",
+			    genl->cmd,
+			    genl->version, genl->reserved);
+
+			size_t cur_len = (sizeof(struct nlmsghdr)
+			    + sizeof(struct genlmsghdr));
+			size_t nla_len = nl->nlmsg_len - cur_len;
+
+			const struct nlattr *nla;
+			const struct nlattr *nla_head = (const struct nlattr *)
+			    (const void *)((const char *)nl + cur_len);
+
+			NLA_FOREACH_CONST(nla, nla_head, nla_len) {
+				switch (nla->nla_type) {
+				case CTRL_ATTR_FAMILY_ID:
+					memcpy(&family_id, NLA_DATA_CONST(nla),
+					    sizeof(family_id));
+					fprintf(fp, ",family_id=%u", family_id);
+					break;
+				case CTRL_ATTR_FAMILY_NAME:
+					family_name =
+					    ((const char *)NLA_DATA_CONST(nla));
+					fprintf(fp, ",family_name=%s",
+					    family_name);
+					break;
+				default:
+					break;
+				}
+			}
+
+			fprintf(fp, "}");
+			break;
 		default:
 			fprintf(fp, "%u", nl->nlmsg_type);
 			break;
 		}
 
-		fprintf(fp, ",flags=");
-		const char *nlm_f = sysdecode_nlm_flag(nl->nlmsg_flags);
-		if (nlm_f != NULL)
-			fprintf(fp, "%s", nlm_f);
-		else
-			fprintf(fp, "0x%x", nl->nlmsg_flags);
-
-		fprintf(fp, ",seq=%u,pid=%u", nl->nlmsg_seq, nl->nlmsg_pid);
-
 		/* Handle Alignment (Netlink messages are 4-byte aligned). */
 		size_t aligned_len = NLMSG_ALIGN(nl->nlmsg_len);
 		if (aligned_len > remaining)