From 8ad5e44cbaea616885bfc5cb032d911089383fe5 Mon Sep 17 00:00:00 2001
From: Martine Lenders <mail@martine-lenders.eu>
Date: Wed, 9 Jan 2019 22:14:08 +0100
Subject: [PATCH] sock_dns: remove some magic numbers
---
sys/include/net/dns.h | 42 +++++++++++++++++++++++++++++
sys/net/application_layer/dns/dns.c | 14 +++++-----
2 files changed, 50 insertions(+), 6 deletions(-)
create mode 100644 sys/include/net/dns.h
diff --git a/sys/include/net/dns.h b/sys/include/net/dns.h
new file mode 100644
index 0000000000..09ee148e16
--- /dev/null
+++ b/sys/include/net/dns.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2019 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup net_dns DNS defines
+ * @ingroup net
+ * @brief Generic DNS values
+ * @{
+ *
+ * @file
+ * @brief Generic DNS values
+ *
+ * @author Martine Lenders <m.lenders@fu-berlin.de>
+ */
+#ifndef NET_DNS_H
+#define NET_DNS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @name Field lengths
+ * @{
+ */
+#define RR_TYPE_LENGTH (2U)
+#define RR_CLASS_LENGTH (2U)
+#define RR_TTL_LENGTH (4U)
+#define RR_RDLENGTH_LENGTH (2U)
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_DNS_H */
+/** @} */
diff --git a/sys/net/application_layer/dns/dns.c b/sys/net/application_layer/dns/dns.c
index 8bda172367..55a1f63e54 100644
--- a/sys/net/application_layer/dns/dns.c
+++ b/sys/net/application_layer/dns/dns.c
@@ -19,6 +19,7 @@
#include <string.h>
#include <stdio.h>
+#include "net/dns.h"
#include "net/sock/udp.h"
#include "net/sock/dns.h"
@@ -114,7 +115,8 @@ static int _parse_dns_reply(uint8_t *buf, size_t len, void* addr_out, int family
return tmp;
}
bufpos += tmp;
- bufpos += 4; /* skip type and class of query */
+ /* skip type and class of query */
+ bufpos += (RR_TYPE_LENGTH + RR_CLASS_LENGTH);
}
for (unsigned n = 0; n < ntohs(hdr->ancount); n++) {
@@ -123,14 +125,14 @@ static int _parse_dns_reply(uint8_t *buf, size_t len, void* addr_out, int family
return tmp;
}
bufpos += tmp;
- if ((bufpos + 2 + 2 + 4) >= buflim) {
+ if ((bufpos + RR_TYPE_LENGTH + RR_CLASS_LENGTH + RR_TTL_LENGTH) >= buflim) {
return -EBADMSG;
}
uint16_t _type = ntohs(_get_short(bufpos));
- bufpos += 2;
+ bufpos += RR_TYPE_LENGTH;
uint16_t class = ntohs(_get_short(bufpos));
- bufpos += 2;
- bufpos += 4; /* skip ttl */
+ bufpos += RR_CLASS_LENGTH;
+ bufpos += RR_TTL_LENGTH; /* skip ttl */
unsigned addrlen = ntohs(_get_short(bufpos));
/* skip unwanted answers */
@@ -154,7 +156,7 @@ static int _parse_dns_reply(uint8_t *buf, size_t len, void* addr_out, int family
(family == AF_UNSPEC))) {
return -EBADMSG;
}
- bufpos += 2;
+ bufpos += RR_RDLENGTH_LENGTH;
if ((bufpos + addrlen) >= buflim) {
return -EBADMSG;
}
--
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