[388] | 1 | #define _BSD_SOURCE
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| 2 | #include <errno.h>
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| 3 | #include <stddef.h>
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| 4 | #include <resolv.h>
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| 5 | #include <arpa/nameser.h>
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| 6 |
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| 7 | const struct _ns_flagdata _ns_flagdata[16] = {
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| 8 | { 0x8000, 15 },
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| 9 | { 0x7800, 11 },
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| 10 | { 0x0400, 10 },
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| 11 | { 0x0200, 9 },
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| 12 | { 0x0100, 8 },
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| 13 | { 0x0080, 7 },
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| 14 | { 0x0040, 6 },
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| 15 | { 0x0020, 5 },
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| 16 | { 0x0010, 4 },
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| 17 | { 0x000f, 0 },
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| 18 | { 0x0000, 0 },
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| 19 | { 0x0000, 0 },
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| 20 | { 0x0000, 0 },
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| 21 | { 0x0000, 0 },
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| 22 | { 0x0000, 0 },
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| 23 | { 0x0000, 0 },
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| 24 | };
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| 25 |
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| 26 | unsigned ns_get16(const unsigned char *cp)
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| 27 | {
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| 28 | return cp[0]<<8 | cp[1];
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| 29 | }
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| 30 |
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| 31 | unsigned long ns_get32(const unsigned char *cp)
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| 32 | {
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| 33 | return (unsigned)cp[0]<<24 | cp[1]<<16 | cp[2]<<8 | cp[3];
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| 34 | }
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| 35 |
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| 36 | void ns_put16(unsigned s, unsigned char *cp)
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| 37 | {
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| 38 | *cp++ = s>>8;
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| 39 | *cp++ = s;
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| 40 | }
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| 41 |
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| 42 | void ns_put32(unsigned long l, unsigned char *cp)
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| 43 | {
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| 44 | *cp++ = l>>24;
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| 45 | *cp++ = l>>16;
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| 46 | *cp++ = l>>8;
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| 47 | *cp++ = l;
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| 48 | }
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| 49 |
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| 50 | int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle)
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| 51 | {
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| 52 | int i, r;
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| 53 |
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| 54 | handle->_msg = msg;
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| 55 | handle->_eom = msg + msglen;
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| 56 | if (msglen < (2 + ns_s_max) * NS_INT16SZ) goto bad;
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| 57 | NS_GET16(handle->_id, msg);
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| 58 | NS_GET16(handle->_flags, msg);
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| 59 | for (i = 0; i < ns_s_max; i++) NS_GET16(handle->_counts[i], msg);
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| 60 | for (i = 0; i < ns_s_max; i++) {
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| 61 | if (handle->_counts[i]) {
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| 62 | handle->_sections[i] = msg;
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| 63 | r = ns_skiprr(msg, handle->_eom, i, handle->_counts[i]);
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| 64 | if (r < 0) return -1;
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| 65 | msg += r;
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| 66 | } else {
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| 67 | handle->_sections[i] = NULL;
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| 68 | }
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| 69 | }
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| 70 | if (msg != handle->_eom) goto bad;
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| 71 | handle->_sect = ns_s_max;
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| 72 | handle->_rrnum = -1;
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| 73 | handle->_msg_ptr = NULL;
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| 74 | return 0;
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| 75 | bad:
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| 76 | errno = EMSGSIZE;
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| 77 | return -1;
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| 78 | }
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| 79 |
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| 80 | int ns_skiprr(const unsigned char *ptr, const unsigned char *eom, ns_sect section, int count)
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| 81 | {
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| 82 | const unsigned char *p = ptr;
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| 83 | int r;
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| 84 |
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| 85 | while (count--) {
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| 86 | r = dn_skipname(p, eom);
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| 87 | if (r < 0) goto bad;
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| 88 | if (r + 2 * NS_INT16SZ > eom - p) goto bad;
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| 89 | p += r + 2 * NS_INT16SZ;
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| 90 | if (section != ns_s_qd) {
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| 91 | if (NS_INT32SZ + NS_INT16SZ > eom - p) goto bad;
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| 92 | p += NS_INT32SZ;
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| 93 | NS_GET16(r, p);
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| 94 | if (r > eom - p) goto bad;
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| 95 | p += r;
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| 96 | }
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| 97 | }
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| 98 | return p - ptr;
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| 99 | bad:
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| 100 | errno = EMSGSIZE;
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| 101 | return -1;
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| 102 | }
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| 103 |
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| 104 | int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr)
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| 105 | {
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| 106 | int r;
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| 107 |
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| 108 | if (section < 0 || section >= ns_s_max) goto bad;
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| 109 | if (section != handle->_sect) {
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| 110 | handle->_sect = section;
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| 111 | handle->_rrnum = 0;
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| 112 | handle->_msg_ptr = handle->_sections[section];
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| 113 | }
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| 114 | if (rrnum == -1) rrnum = handle->_rrnum;
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| 115 | if (rrnum < 0 || rrnum >= handle->_counts[section]) goto bad;
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| 116 | if (rrnum < handle->_rrnum) {
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| 117 | handle->_rrnum = 0;
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| 118 | handle->_msg_ptr = handle->_sections[section];
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| 119 | }
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| 120 | if (rrnum > handle->_rrnum) {
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| 121 | r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum);
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| 122 | if (r < 0) return -1;
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| 123 | handle->_msg_ptr += r;
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| 124 | handle->_rrnum = rrnum;
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| 125 | }
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| 126 | r = ns_name_uncompress(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME);
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| 127 | if (r < 0) return -1;
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| 128 | handle->_msg_ptr += r;
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| 129 | if (2 * NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size;
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| 130 | NS_GET16(rr->type, handle->_msg_ptr);
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| 131 | NS_GET16(rr->rr_class, handle->_msg_ptr);
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| 132 | if (section != ns_s_qd) {
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| 133 | if (NS_INT32SZ + NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size;
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| 134 | NS_GET32(rr->ttl, handle->_msg_ptr);
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| 135 | NS_GET16(rr->rdlength, handle->_msg_ptr);
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| 136 | if (rr->rdlength > handle->_eom - handle->_msg_ptr) goto size;
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| 137 | rr->rdata = handle->_msg_ptr;
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| 138 | handle->_msg_ptr += rr->rdlength;
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| 139 | } else {
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| 140 | rr->ttl = 0;
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| 141 | rr->rdlength = 0;
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| 142 | rr->rdata = NULL;
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| 143 | }
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| 144 | handle->_rrnum++;
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| 145 | if (handle->_rrnum > handle->_counts[section]) {
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| 146 | handle->_sect = section + 1;
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| 147 | if (handle->_sect == ns_s_max) {
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| 148 | handle->_rrnum = -1;
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| 149 | handle->_msg_ptr = NULL;
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| 150 | } else {
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| 151 | handle->_rrnum = 0;
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| 152 | }
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| 153 | }
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| 154 | return 0;
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| 155 | bad:
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| 156 | errno = ENODEV;
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| 157 | return -1;
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| 158 | size:
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| 159 | errno = EMSGSIZE;
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| 160 | return -1;
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| 161 | }
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| 162 |
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| 163 | int ns_name_uncompress(const unsigned char *msg, const unsigned char *eom,
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| 164 | const unsigned char *src, char *dst, size_t dstsiz)
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| 165 | {
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| 166 | int r;
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| 167 | r = dn_expand(msg, eom, src, dst, dstsiz);
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| 168 | if (r < 0) errno = EMSGSIZE;
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| 169 | return r;
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| 170 | }
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| 171 |
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