1#define _BSD_SOURCE 2#include <errno.h> 3#include <stddef.h> 4#include <resolv.h> 5#include <arpa/nameser.h> 6 7const struct _ns_flagdata _ns_flagdata[16] = { 8 { 0x8000, 15 }, 9 { 0x7800, 11 }, 10 { 0x0400, 10 }, 11 { 0x0200, 9 }, 12 { 0x0100, 8 }, 13 { 0x0080, 7 }, 14 { 0x0040, 6 }, 15 { 0x0020, 5 }, 16 { 0x0010, 4 }, 17 { 0x000f, 0 }, 18 { 0x0000, 0 }, 19 { 0x0000, 0 }, 20 { 0x0000, 0 }, 21 { 0x0000, 0 }, 22 { 0x0000, 0 }, 23 { 0x0000, 0 }, 24}; 25 26unsigned ns_get16(const unsigned char *cp) 27{ 28 return cp[0]<<8 | cp[1]; 29} 30 31unsigned long ns_get32(const unsigned char *cp) 32{ 33 return (unsigned)cp[0]<<24 | cp[1]<<16 | cp[2]<<8 | cp[3]; 34} 35 36void ns_put16(unsigned s, unsigned char *cp) 37{ 38 *cp++ = s>>8; 39 *cp++ = s; 40} 41 42void ns_put32(unsigned long l, unsigned char *cp) 43{ 44 *cp++ = l>>24; 45 *cp++ = l>>16; 46 *cp++ = l>>8; 47 *cp++ = l; 48} 49 50int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle) 51{ 52 int i, r; 53 54 handle->_msg = msg; 55 handle->_eom = msg + msglen; 56 if (msglen < (2 + ns_s_max) * NS_INT16SZ) goto bad; 57 NS_GET16(handle->_id, msg); 58 NS_GET16(handle->_flags, msg); 59 for (i = 0; i < ns_s_max; i++) NS_GET16(handle->_counts[i], msg); 60 for (i = 0; i < ns_s_max; i++) { 61 if (handle->_counts[i]) { 62 handle->_sections[i] = msg; 63 r = ns_skiprr(msg, handle->_eom, i, handle->_counts[i]); 64 if (r < 0) return -1; 65 msg += r; 66 } else { 67 handle->_sections[i] = NULL; 68 } 69 } 70 if (msg != handle->_eom) goto bad; 71 handle->_sect = ns_s_max; 72 handle->_rrnum = -1; 73 handle->_msg_ptr = NULL; 74 return 0; 75bad: 76 errno = EMSGSIZE; 77 return -1; 78} 79 80int ns_skiprr(const unsigned char *ptr, const unsigned char *eom, ns_sect section, int count) 81{ 82 const unsigned char *p = ptr; 83 int r; 84 85 while (count--) { 86 r = dn_skipname(p, eom); 87 if (r < 0) goto bad; 88 if (r + 2 * NS_INT16SZ > eom - p) goto bad; 89 p += r + 2 * NS_INT16SZ; 90 if (section != ns_s_qd) { 91 if (NS_INT32SZ + NS_INT16SZ > eom - p) goto bad; 92 p += NS_INT32SZ; 93 NS_GET16(r, p); 94 if (r > eom - p) goto bad; 95 p += r; 96 } 97 } 98 return p - ptr; 99bad: 100 errno = EMSGSIZE; 101 return -1; 102} 103 104int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) 105{ 106 int r; 107 108 if (section < 0 || section >= ns_s_max) goto bad; 109 if (section != handle->_sect) { 110 handle->_sect = section; 111 handle->_rrnum = 0; 112 handle->_msg_ptr = handle->_sections[section]; 113 } 114 if (rrnum == -1) rrnum = handle->_rrnum; 115 if (rrnum < 0 || rrnum >= handle->_counts[section]) goto bad; 116 if (rrnum < handle->_rrnum) { 117 handle->_rrnum = 0; 118 handle->_msg_ptr = handle->_sections[section]; 119 } 120 if (rrnum > handle->_rrnum) { 121 r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum); 122 if (r < 0) return -1; 123 handle->_msg_ptr += r; 124 handle->_rrnum = rrnum; 125 } 126 r = ns_name_uncompress(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME); 127 if (r < 0) return -1; 128 handle->_msg_ptr += r; 129 if (2 * NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size; 130 NS_GET16(rr->type, handle->_msg_ptr); 131 NS_GET16(rr->rr_class, handle->_msg_ptr); 132 if (section != ns_s_qd) { 133 if (NS_INT32SZ + NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size; 134 NS_GET32(rr->ttl, handle->_msg_ptr); 135 NS_GET16(rr->rdlength, handle->_msg_ptr); 136 if (rr->rdlength > handle->_eom - handle->_msg_ptr) goto size; 137 rr->rdata = handle->_msg_ptr; 138 handle->_msg_ptr += rr->rdlength; 139 } else { 140 rr->ttl = 0; 141 rr->rdlength = 0; 142 rr->rdata = NULL; 143 } 144 handle->_rrnum++; 145 if (handle->_rrnum > handle->_counts[section]) { 146 handle->_sect = section + 1; 147 if (handle->_sect == ns_s_max) { 148 handle->_rrnum = -1; 149 handle->_msg_ptr = NULL; 150 } else { 151 handle->_rrnum = 0; 152 } 153 } 154 return 0; 155bad: 156 errno = ENODEV; 157 return -1; 158size: 159 errno = EMSGSIZE; 160 return -1; 161} 162 163int ns_name_uncompress(const unsigned char *msg, const unsigned char *eom, 164 const unsigned char *src, char *dst, size_t dstsiz) 165{ 166 int r; 167 r = dn_expand(msg, eom, src, dst, dstsiz); 168 if (r < 0) errno = EMSGSIZE; 169 return r; 170} 171 172