Sometimes it is helpful to see a hexdump of the additional notification
data sent since it may provide the needed info to better understand why
the notification was triggered.

This diff adds this extra logging for UPDATE if verbose is on.
-- 
:wq Claudio

Index: logmsg.c
===================================================================
RCS file: /cvs/src/usr.sbin/bgpd/logmsg.c,v
diff -u -p -r1.15 logmsg.c
--- logmsg.c	21 Aug 2025 15:15:25 -0000	1.15
+++ logmsg.c	9 Sep 2025 11:33:36 -0000
@@ -128,6 +128,27 @@ log_statechange(struct peer *peer, enum 
 	    eventnames[event]);
 }
 
+static const char *
+tohex(const unsigned char *in, size_t len)
+{
+	const char hex[] = "0123456789ABCDEF";
+	static char out[(16 + 1) * 3];
+	size_t i, o = 0;
+
+	if (len > 16)
+		len = 16;
+	for (i = 0; i < len; i++) {
+		out[o++] = hex[in[i] >> 4];
+		out[o++] = hex[in[i] & 0xf];
+		out[o++] = ' ';
+		if (i == 7)
+			out[o++] = ' ';
+	}
+	out[o - 1] = '\0';
+
+	return out;
+}
+
 void
 log_notification(const struct peer *peer, uint8_t errcode, uint8_t subcode,
     const struct ibuf *data, const char *dir)
@@ -135,7 +156,7 @@ log_notification(const struct peer *peer
 	struct ibuf	 ibuf;
 	char		*p;
 	const char	*suberrname = NULL;
-	int		 uk = 0;
+	int		 uk = 0, dump = 0;
 
 	if (data != NULL)
 		ibuf_from_ibuf(&ibuf, data);
@@ -176,6 +197,7 @@ log_notification(const struct peer *peer
 			uk = 1;
 		else
 			suberrname = suberr_update_names[subcode];
+		dump = 1;
 		break;
 	case ERR_CEASE:
 		if (subcode >= sizeof(suberr_cease_names) / sizeof(char *) ||
@@ -238,6 +260,23 @@ log_notification(const struct peer *peer
 			logit(LOG_ERR, "%s: %s notification: %s, %s",
 			    p, dir, errnames[errcode], suberrname);
 	}
+
+	if (dump && log_getverbose() && ibuf_size(&ibuf) > 0) {
+		size_t off = 0;
+		logit(LOG_INFO, "%s: notification data", p);
+		while (ibuf_size(&ibuf) > 0) {
+			unsigned char buf[16];
+			size_t len = sizeof(buf);
+			if (ibuf_size(&ibuf) < len)
+				len = ibuf_size(&ibuf);
+			if (ibuf_get(&ibuf, buf, len) == -1) {
+				break;
+			}
+			logit(LOG_INFO, "   %5zu: %s", off, tohex(buf, len));
+			off += len;
+		}
+	}
+
 	free(p);
 }