From: Willem Toorop <willem@nlnetlabs.nl>
Date: Mon, 19 Jan 2026 14:16:56 +0000 (+0100)
Subject: reserve enough space for str in ldns_pkt2str_fmt
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5a5a938f358e0037328f7091aac9f5604b8bf7ec;p=thirdparty%2Fldns.git

reserve enough space for str in ldns_pkt2str_fmt

Also, let ldns_pkt_print_fmt report the error if converting the host format
to presentation format failed.
---

diff --git a/Changelog b/Changelog
index 6106b66b..bd5290c1 100644
--- a/Changelog
+++ b/Changelog
@@ -4,6 +4,8 @@
 	* Fix memory leak in ldns-notify
 	* Prevent "null pointer pass as 2nd argument to memcpy" runtime
 	  error, when size is 0
+	* Fix to reserve enough space to convert the largest packets to
+	  presentation format in ldns_pkt2str_fmt. Thanks Peter Kästle
 	
 1.9.0	2025-12-04
 	* PR #246: Make ldns_calc_keytag() available for CDNSKEY RR
diff --git a/host2str.c b/host2str.c
index 9f2795af..efa1bf87 100644
--- a/host2str.c
+++ b/host2str.c
@@ -3374,24 +3374,33 @@ ldns_rr2str(const ldns_rr *rr)
 }
 
 char *
-ldns_pkt2str_fmt(const ldns_output_format *fmt, const ldns_pkt *pkt)
+ldns_pkt2str_fmt_status(const ldns_output_format *fmt, const ldns_pkt *pkt,
+		ldns_status *return_status)
 {
 	char *result = NULL;
-	ldns_buffer *tmp_buffer = ldns_buffer_new(LDNS_MAX_PACKETLEN);
+	ldns_status s;
+	ldns_buffer *tmp_buffer = ldns_buffer_new(LDNS_MAX_PACKETLEN * 5);
 
 	if (!tmp_buffer) {
 		return NULL;
 	}
-	if (ldns_pkt2buffer_str_fmt(tmp_buffer, fmt, pkt)
-		       	== LDNS_STATUS_OK) {
+	if ((s = ldns_pkt2buffer_str_fmt(tmp_buffer, fmt, pkt))
+		       == LDNS_STATUS_OK) {
 		/* export and return string, destroy rest */
 		result = ldns_buffer_export2str(tmp_buffer);
 	}
-
 	ldns_buffer_free(tmp_buffer);
+	if (return_status)
+		*return_status = s;
 	return result;
 }
 
+char *
+ldns_pkt2str_fmt(const ldns_output_format *fmt, const ldns_pkt *pkt)
+{
+	return ldns_pkt2str_fmt_status(fmt, pkt, NULL);
+}
+
 char *
 ldns_pkt2str(const ldns_pkt *pkt)
 {
@@ -3485,11 +3494,13 @@ void
 ldns_pkt_print_fmt(FILE *output, 
 		const ldns_output_format *fmt, const ldns_pkt *pkt)
 {
-	char *str = ldns_pkt2str_fmt(fmt, pkt);
+	ldns_status s = LDNS_STATUS_OK;
+	char *str = ldns_pkt2str_fmt_status(fmt, pkt, &s);
 	if (str) {
 		fprintf(output, "%s", str);
 	} else {
-		fprintf(output, ";Unable to convert packet to string\n");
+		fprintf(output, ";Unable to convert packet to string%s%s\n",
+			(s ? ": " : ""), (s ? ldns_get_errorstr_by_id(s) : ""));
 	}
 	LDNS_FREE(str);
 }