Description

A NAPTR record in dns cache may be skipped if all IPs are unreachable. The NAPTR record contains the internal parameter skip_record. From outside, it is not possible to view the state of a certain NAPTR record.

Extend the return value of dns_cache_print_entry with the parameter skip_record.

Expected behavior

The answer of kamcmd dns.view shows yes or no depending on the internal state of skip_record.

{
	name: skipped.example.com
	type: NAPTR
	size_bytes: 208
	reference_counter: 2
	permanent: no
	expires: 268
	last_used: 29
	negative_entry: no
	records: {
		{
			rr_idx: 0
			rr_order: 10
			rr_preference: 10
->			rr_skip_record: yes
			rr_flags: S
			rr_service: SIPS+D2T
			rr_regexp: 
			rr_regexp: _sips._tcp.skipped.example.com
			rr_permanent: no
			rr_expires: 268
		}
	}
}
{
	name: valid.example.com
	type: NAPTR
	size_bytes: 328
	reference_counter: 1
	permanent: no
	expires: 294
	last_used: 5
	negative_entry: no
	records: {
		{
			rr_idx: 0
			rr_order: 20
			rr_preference: 20
->			rr_skip_record: no
			rr_flags: S
			rr_service: SIP+D2U
			rr_regexp: 
			rr_regexp: _sip._udp.valid.example.com
			rr_permanent: no
			rr_expires: 294
		}
		{
			rr_idx: 1
			rr_order: 10
			rr_preference: 10
->			rr_skip_record: no
			rr_flags: S
			rr_service: SIPS+D2T
			rr_regexp: 
			rr_regexp: _sips._tcp.valid.example.com
			rr_permanent: no
			rr_expires: 294
		}
	}
}

Actual observed behavior

At the moment it is not visible why a NAPTR record is not used.

Possible Solutions

The following patch extends the output of dns_cache_print_entry with the parameter rr_skip_record.

The patch has been tested locally.

From c4d559f12892fb5a2c3b572f9660b637299fcafb Mon Sep 17 00:00:00 2001
From: Mathias Schneuwly <mathias.schneuwly@ruag.ch>
Date: Tue, 11 Mar 2025 12:38:44 +0000
Subject: [PATCH] Print parameter skip_record in dns_cache_print_entry

---
 src/core/dns_cache.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/core/dns_cache.c b/src/core/dns_cache.c
index 1507e89015..1bb95a2d41 100644
--- a/src/core/dns_cache.c
+++ b/src/core/dns_cache.c
@@ -3898,6 +3898,13 @@ int dns_cache_print_entry(rpc_t *rpc, void *ctx, struct dns_hash_entry *e)
 					rpc->fault(ctx, 500, "Internal error adding naptr order");
 					return -1;
 				}
+				if(rpc->struct_add(sh, "s", "rr_skip_record",
+							((struct naptr_rdata *)(rr->rdata))->skip_record ? "yes" : "no")
+							< 0) {
+					rpc->fault(
+						ctx, 500, "Internal error adding naptr rr_skip_record");
+					return -1;
+				}
 				s.s = ((struct naptr_rdata *)(rr->rdata))->flags;
 				s.len = ((struct naptr_rdata *)(rr->rdata))->flags_len;
 				if(rpc->struct_add(sh, "S", "rr_flags", &s) < 0) {
-- 
2.44.1

Additional Information

Kamailio Version - output of kamailio -v

version: kamailio 5.8.4 (x86_64/linux) f1d83d
flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, MEM_JOIN_FREE, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLOCKLIST, HAVE_RESOLV_RES
ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_SEND_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB
poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
id: f1d83d

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schneuwlym created an issue (kamailio/kamailio#4174)