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From cc449aebaa572fbea2d400d1ee058f03f2638df2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>
Date: Mon, 14 Oct 2013 10:01:01 +0300
Subject: [PATCH] add basic dns record parsing functions
---
include/arpa/nameser.h | 89 ++++++++++++++++++-------------
src/network/ns_parse.c | 140 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 192 insertions(+), 37 deletions(-)
create mode 100644 src/network/ns_parse.c
diff --git a/include/arpa/nameser.h b/include/arpa/nameser.h
index b9ee665..1fc7339 100644
--- a/include/arpa/nameser.h
+++ b/include/arpa/nameser.h
@@ -1,6 +1,11 @@
#ifndef _ARPA_NAMESER_H
#define _ARPA_NAMESER_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/types.h>
#include <stdint.h>
#define __NAMESER 19991006
@@ -296,43 +301,49 @@ typedef enum __ns_cert_types {
#define NS_OPT_DNSSEC_OK 0x8000U
#define NS_OPT_NSID 3
-#define NS_GET16(s, cp) do { \
- register const unsigned char *t_cp = (const unsigned char *)(cp); \
- (s) = ((uint16_t)t_cp[0] << 8) \
- | ((uint16_t)t_cp[1]) \
- ; \
- (cp) += NS_INT16SZ; \
-} while (0)
-
-#define NS_GET32(l, cp) do { \
- register const unsigned char *t_cp = (const unsigned char *)(cp); \
- (l) = ((uint32_t)t_cp[0] << 24) \
- | ((uint32_t)t_cp[1] << 16) \
- | ((uint32_t)t_cp[2] << 8) \
- | ((uint32_t)t_cp[3]) \
- ; \
- (cp) += NS_INT32SZ; \
-} while (0)
-
-#define NS_PUT16(s, cp) do { \
- register uint16_t t_s = (uint16_t)(s); \
- register unsigned char *t_cp = (unsigned char *)(cp); \
- *t_cp++ = t_s >> 8; \
- *t_cp = t_s; \
- (cp) += NS_INT16SZ; \
-} while (0)
-
-#define NS_PUT32(l, cp) do { \
- register uint32_t t_l = (uint32_t)(l); \
- register unsigned char *t_cp = (unsigned char *)(cp); \
- *t_cp++ = t_l >> 24; \
- *t_cp++ = t_l >> 16; \
- *t_cp++ = t_l >> 8; \
- *t_cp = t_l; \
- (cp) += NS_INT32SZ; \
-} while (0)
-
-
+static __inline uint16_t ns_get16(const unsigned char *cp)
+{
+ return ((uint16_t)cp[0] << 8)
+ | ((uint16_t)cp[1]);
+}
+
+#define NS_GET16(s, cp) do { (s) = ns_get16(cp); (cp) += NS_INT16SZ; } while (0)
+
+static __inline uint32_t ns_get32(const unsigned char *cp)
+{
+ return ((uint32_t)cp[0] << 24)
+ | ((uint32_t)cp[1] << 16)
+ | ((uint32_t)cp[2] << 8)
+ | ((uint32_t)cp[3]);
+}
+
+#define NS_GET32(s, cp) do { (s) = ns_get32(cp); (cp) += NS_INT32SZ; } while (0)
+
+static __inline void ns_put16(uint16_t s, unsigned char *cp)
+{
+ cp[0] = s >> 8;
+ cp[1] = s;
+}
+
+#define NS_PUT16(s, cp) do { ns_put16(s, cp); (cp) += NS_INT16SZ; } while (0)
+
+static __inline void ns_put32(uint32_t l, unsigned char *cp)
+{
+ cp[0] = l >> 24;
+ cp[1] = l >> 16;
+ cp[2] = l >> 8;
+ cp[3] = l;
+}
+
+#define NS_PUT32(s, cp) do { ns_put32(s, cp); (cp) += NS_INT32SZ; } while (0)
+
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+int ns_initparse(const u_char *msg, int msglen, ns_msg *handle);
+int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr);
+int ns_skiprr(const u_char *msg, const u_char *eom, ns_sect section, int count);
+int ns_name_uncompress(const u_char *msg, const u_char *eom,
+ const u_char *comp_dn, char *exp_dn, size_t length);
+#endif
#define __BIND 19950621
@@ -464,4 +475,8 @@ typedef struct {
#define PUTSHORT NS_PUT16
#define PUTLONG NS_PUT32
+#ifdef __cplusplus
+}
+#endif
+
#endif
diff --git a/src/network/ns_parse.c b/src/network/ns_parse.c
new file mode 100644
index 0000000..5ef0d90
--- /dev/null
+++ b/src/network/ns_parse.c
@@ -0,0 +1,140 @@
+#define _BSD_SOURCE
+#include <errno.h>
+#include <stddef.h>
+#include <resolv.h>
+#include <arpa/nameser.h>
+
+int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle)
+{
+ int i, r;
+
+ handle->_msg = msg;
+ handle->_eom = msg + msglen;
+ if (msglen < (2 + ns_s_max) * NS_INT16SZ)
+ goto bad;
+
+ NS_GET16(handle->_id, msg);
+ NS_GET16(handle->_flags, msg);
+ for (i = 0; i < ns_s_max; i++)
+ NS_GET16(handle->_counts[i], msg);
+ for (i = 0; i < ns_s_max; i++) {
+ if (handle->_counts[i]) {
+ handle->_sections[i] = msg;
+ r = ns_skiprr(msg, handle->_eom, i, handle->_counts[i]);
+ if (r < 0) return -1;
+ msg += r;
+ } else {
+ handle->_sections[i] = NULL;
+ }
+ }
+ if (msg != handle->_eom)
+ goto bad;
+
+ handle->_sect = ns_s_max;
+ handle->_rrnum = -1;
+ handle->_msg_ptr = NULL;
+ return 0;
+bad:
+ errno = EMSGSIZE;
+ return -1;
+}
+
+int ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count)
+{
+ const u_char *p = ptr;
+ int r;
+
+ while (count--) {
+ r = dn_skipname(p, eom);
+ if (r < 0) goto bad;
+ p += r + 2 * NS_INT16SZ;
+ if (section != ns_s_qd) {
+ if (p + NS_INT32SZ + NS_INT16SZ > eom) goto bad;
+ p += NS_INT32SZ;
+ NS_GET16(r, p);
+ p += r;
+ }
+ }
+ if (p > eom) goto bad;
+ return ptr - p;
+bad:
+ errno = EMSGSIZE;
+ return -1;
+}
+
+int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr)
+{
+ int r;
+
+ if (section < 0 || section >= ns_s_max)
+ goto bad;
+ if (section != handle->_sect) {
+ handle->_sect = section;
+ handle->_rrnum = 0;
+ handle->_msg_ptr = handle->_sections[section];
+ }
+ if (rrnum == -1)
+ rrnum = handle->_rrnum;
+ if (rrnum < 0 || rrnum >= handle->_counts[section])
+ goto bad;
+ if (rrnum < handle->_rrnum) {
+ handle->_rrnum = 0;
+ handle->_msg_ptr = handle->_sections[section];
+ }
+ if (rrnum > handle->_rrnum) {
+ r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum);
+ if (r < 0) return -1;
+ handle->_msg_ptr += r;
+ handle->_rrnum = rrnum;
+ }
+ r = dn_expand(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME);
+ if (r < 0) return -1;
+ handle->_msg_ptr += r;
+ if (handle->_msg_ptr + 2 * NS_INT16SZ > handle->_eom)
+ goto size;
+ NS_GET16(rr->type, handle->_msg_ptr);
+ NS_GET16(rr->rr_class, handle->_msg_ptr);
+ if (section != ns_s_qd) {
+ if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
+ goto size;
+ NS_GET32(rr->ttl, handle->_msg_ptr);
+ NS_GET16(rr->rdlength, handle->_msg_ptr);
+ if (handle->_msg_ptr + rr->rdlength > handle->_eom)
+ goto size;
+ rr->rdata = handle->_msg_ptr;
+ handle->_msg_ptr += rr->rdlength;
+ } else {
+ rr->ttl = 0;
+ rr->rdlength = 0;
+ rr->rdata = NULL;
+ }
+ handle->_rrnum++;
+ if (handle->_rrnum > handle->_counts[section]) {
+ handle->_sect = section + 1;
+ if (handle->_sect == ns_s_max) {
+ handle->_rrnum = -1;
+ handle->_msg_ptr = NULL;
+ } else {
+ handle->_rrnum = 0;
+ }
+ }
+ return 0;
+bad:
+ errno = ENODEV;
+ return -1;
+size:
+ errno = EMSGSIZE;
+ return -1;
+}
+
+int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
+
+int ns_name_uncompress(const u_char *msg, const u_char *eom,
+ const u_char *src, char *dst, size_t dstsiz)
+{
+ int r;
+ r = __dn_expand(msg, eom, src, dst, dstsiz);
+ if (r < 0) errno = EMSGSIZE;
+ return r;
+}
+
--
1.8.4
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