From 305b5db4ebcef190873bf475d50d1e12738cabc2 Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Mon, 9 Sep 2024 13:09:47 +0200
Subject: [PATCH] dns_msg: add debug output

---
 sys/net/application_layer/dns/msg.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/sys/net/application_layer/dns/msg.c b/sys/net/application_layer/dns/msg.c
index 767c697d87..4cf5758594 100644
--- a/sys/net/application_layer/dns/msg.c
+++ b/sys/net/application_layer/dns/msg.c
@@ -26,6 +26,9 @@
 
 #include "net/dns/msg.h"
 
+#define ENABLE_DEBUG 0
+#include "debug.h"
+
 static ssize_t _enc_domain_name(uint8_t *out, const char *domain_name)
 {
     /*
@@ -76,10 +79,13 @@ static ssize_t _skip_hostname(const uint8_t *buf, size_t len,
 
     if (bufpos >= buflim) {
         /* out-of-bound */
+        DEBUG("dns_msg: bufpos is out of bounds\n");
         return -EBADMSG;
     }
+
     /* handle DNS Message Compression */
-    if (*bufpos >= 192) {
+    if (*bufpos & 0xc0) {
+        DEBUG("dns_msg: hostname is compressed\n");
         if ((bufpos + 2) >= buflim) {
             return -EBADMSG;
         }
@@ -90,6 +96,7 @@ static ssize_t _skip_hostname(const uint8_t *buf, size_t len,
         res += bufpos[res] + 1;
         if ((&bufpos[res]) >= buflim) {
             /* out-of-bound */
+            DEBUG("dns_msg: hostname out-of-bounds\n");
             return -EBADMSG;
         }
     }
@@ -156,6 +163,7 @@ int dns_msg_parse_reply(const uint8_t *buf, size_t len, int family,
         bufpos += tmp;
         if ((bufpos + RR_TYPE_LENGTH + RR_CLASS_LENGTH +
              RR_TTL_LENGTH + sizeof(uint16_t)) >= buflim) {
+            DEBUG("dns_msg: record beyond buf limit");
             return -EBADMSG;
         }
         uint16_t _type = ntohs(_get_short(bufpos));
@@ -173,6 +181,8 @@ int dns_msg_parse_reply(const uint8_t *buf, size_t len, int family,
             return -EBADMSG;
         }
 
+        DEBUG("dns_msg: type: %u, class: %u, len: %u\n", _type, class, addrlen);
+
         /* skip unwanted answers */
         if ((class != DNS_CLASS_IN) ||
                 ((_type == DNS_TYPE_A) && (family == AF_INET6)) ||