From 2f267b57ef0e145e397be571a000a11dc8188af2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timo=20Ter=C3=A4s?= Date: Mon, 14 Oct 2013 10:01:01 +0300 Subject: [PATCH] add basic dns record parsing functions --- include/arpa/nameser.h | 24 ++++++- src/network/ns_parse.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 195 insertions(+), 1 deletion(-) create mode 100644 src/network/ns_parse.c diff --git a/include/arpa/nameser.h b/include/arpa/nameser.h index b9ee665..9c5f990 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 #include #define __NAMESER 19991006 @@ -48,6 +53,8 @@ extern const struct _ns_flagdata _ns_flagdata[]; #define ns_msg_end(handle) ((handle)._eom + 0) #define ns_msg_size(handle) ((handle)._eom - (handle)._msg) #define ns_msg_count(handle, section) ((handle)._counts[section] + 0) +#define ns_msg_getflag(handle, flag) \ + (((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift) typedef struct __ns_rr { char name[NS_MAXDNAME]; @@ -332,7 +339,18 @@ typedef enum __ns_cert_types { (cp) += NS_INT32SZ; \ } while (0) - +#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE) +u_int ns_get16(const unsigned char *cp); +u_long ns_get32(const unsigned char *cp); +void ns_put16(u_int s, unsigned char *cp); +void ns_put32(u_long l, unsigned char *cp); + +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 +482,8 @@ 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..7e40237 --- /dev/null +++ b/src/network/ns_parse.c @@ -0,0 +1,172 @@ +#define _BSD_SOURCE +#include +#include +#include +#include + +const struct _ns_flagdata _ns_flagdata[16] = { + { 0x8000, 15 }, + { 0x7800, 11 }, + { 0x0400, 10 }, + { 0x0200, 9 }, + { 0x0100, 8 }, + { 0x0080, 7 }, + { 0x0040, 6 }, + { 0x0020, 5 }, + { 0x0010, 4 }, + { 0x000f, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, +}; + +u_int ns_get16(const unsigned char *cp) +{ + u_short s; + NS_GET16(s, cp); + return s; +} + +u_long ns_get32(const unsigned char *cp) +{ + u_long l; + NS_GET32(l, cp); + return l; +} + +void ns_put16(u_int s, unsigned char *cp) +{ + NS_PUT16(s, cp); +} + +void ns_put32(u_long l, unsigned char *cp) +{ + NS_PUT32(l, cp); +} + +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; +} + -- 2.0.2