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1 | /********************************************************** |
2 | SixXS - Automatic IPv6 Connectivity Configuration Utility | |
3 | *********************************************************** | |
4 | Copyright 2003-2005 SixXS - http://www.sixxs.net | |
5 | *********************************************************** | |
6 | common/resolver.c - Simple DNS RR lookup function | |
7 | *********************************************************** | |
8 | $Author: jeroen $ | |
9 | $Id: resolver.c,v 1.3 2006-07-23 14:13:57 jeroen Exp $ | |
10 | $Date: 2006-07-23 14:13:57 $ | |
11 | **********************************************************/ | |
12 | ||
13 | #include <stdlib.h> | |
14 | #include <errno.h> | |
15 | #include <stdio.h> | |
16 | #include <string.h> | |
17 | ||
18 | #include "resolver.h" | |
19 | ||
20 | #ifndef _WIN32 | |
21 | #include <unistd.h> | |
22 | #include <netinet/in.h> | |
23 | #include <arpa/nameser.h> | |
24 | #include <resolv.h> | |
25 | #include <netdb.h> | |
26 | ||
27 | int getrrs(const char *label, int rrtype, void gotrec(unsigned int num, int type, const char *record)) | |
28 | { | |
29 | #ifdef _LINUX | |
30 | struct __res_state res; | |
31 | #endif | |
32 | unsigned char answer[8192]; | |
33 | HEADER *header = (HEADER *)answer; | |
34 | char buf[2048]; | |
35 | int ret, count; | |
36 | unsigned int i,j,k,rrnum = 0; | |
37 | unsigned char *startptr, *endptr, *ptr; | |
38 | uint16_t type = 0, class = 0; | |
39 | uint32_t ttl = 0; | |
40 | ||
41 | #ifdef _LINUX | |
42 | memset(&res, 0, sizeof(res)); | |
43 | res.options = RES_DEBUG; | |
44 | res_ninit(&res); | |
45 | #else | |
46 | res_init(); | |
47 | #endif | |
48 | ||
49 | memset(answer, 0, sizeof(answer)); | |
50 | #ifdef _LINUX | |
51 | ret = res_nquery(&res, label, C_IN, rrtype, answer, sizeof(answer)); | |
52 | #else | |
53 | ret = res_query(label, C_IN, rrtype, answer, sizeof(answer)); | |
54 | #endif | |
55 | if (ret < 0) return -1; | |
56 | ||
57 | /* Our start and end */ | |
58 | startptr = &answer[0]; | |
59 | endptr = &answer[ret]; | |
60 | ||
61 | /* Skip the header */ | |
62 | ptr = startptr + HFIXEDSZ; | |
63 | ||
64 | /* Skip Query part */ | |
65 | for (count = ntohs(header->qdcount); count--; ptr += ret + QFIXEDSZ) | |
66 | { | |
67 | if ((ret = dn_skipname(ptr, endptr)) < 0) return -1; | |
68 | } | |
69 | ||
70 | /* Only look at the Answer section */ | |
71 | count = ntohs(header->ancount); | |
72 | ||
73 | /* Go through all the Answer records */ | |
74 | while (ptr < endptr && count > 0) | |
75 | { | |
76 | rrnum++; | |
77 | ||
78 | memset(buf, 0, sizeof(buf)); | |
79 | ret = dn_expand (startptr, endptr, ptr, buf, sizeof(buf)); | |
80 | if (ret < 0) break; | |
81 | ptr += ret; | |
82 | ||
83 | if (ptr + INT16SZ + INT16SZ + INT32SZ >= endptr) break; | |
84 | ||
85 | /* Get the type */ | |
86 | NS_GET16(type, ptr); | |
87 | ||
88 | /* Get the class */ | |
89 | NS_GET16(class, ptr); | |
90 | ||
91 | /* Get the TTL */ | |
92 | NS_GET32(ttl, ptr); | |
93 | ||
94 | /* Get the RDLength */ | |
95 | NS_GET16(ret, ptr); | |
96 | ||
97 | memset(buf, 0, sizeof(buf)); | |
98 | ||
99 | switch (type) | |
100 | { | |
101 | case T_TXT: | |
102 | for (k = ret, j = 0; j < k && &ptr[j] < endptr; j += (i+1)) | |
103 | { | |
104 | i = ptr[j]; | |
105 | memcpy(buf, &ptr[j+1], i > sizeof(buf) ? sizeof(buf) : i); | |
106 | buf[i > sizeof(buf) ? sizeof(buf) : i] = '\0'; | |
107 | if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf); | |
108 | } | |
109 | break; | |
110 | ||
111 | case T_A: | |
112 | inet_ntop(AF_INET, ptr, buf, sizeof(buf)); | |
113 | if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf); | |
114 | break; | |
115 | ||
116 | case T_AAAA: | |
117 | inet_ntop(AF_INET6, ptr, buf, sizeof(buf)); | |
118 | if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf); | |
119 | break; | |
120 | ||
121 | case T_MX: | |
122 | /* Get the MX preference */ | |
123 | NS_GET16(ttl, ptr); | |
124 | ret = dn_expand(startptr, endptr, ptr, buf, sizeof(buf)); | |
125 | if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf); | |
126 | break; | |
127 | ||
128 | case T_NS: | |
129 | ret = dn_expand(startptr, endptr, ptr, buf, sizeof(buf)); | |
130 | if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf); | |
131 | break; | |
132 | ||
133 | default: | |
134 | /* Unhandled */ | |
135 | break; | |
136 | } | |
137 | ||
138 | ptr += ret; | |
139 | count--; | |
140 | } | |
141 | return 0; | |
142 | } | |
143 | #else | |
144 | /* | |
145 | * Windows Resolver Code, as per: | |
146 | * http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dns/dns/dnsquery.asp | |
147 | * http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B831226 | |
148 | */ | |
149 | #include <windns.h> | |
150 | ||
151 | int getrrs(const char *label, int rrtype, void gotrec(unsigned int num, int type, const char *record)) | |
152 | { | |
153 | DNS_STATUS status; /* Return value of DnsQuery_A() function */ | |
154 | PDNS_RECORD pResult, pRec; /* Pointer to DNS_RECORD structure */ | |
155 | unsigned int rrnum = 0, i; | |
156 | uint16_t type; | |
157 | ||
158 | status = DnsQuery(label, /* Pointer to OwnerName */ | |
159 | rrtype, /* Type of the record to be queried */ | |
160 | DNS_QUERY_STANDARD, /* Standard Query */ | |
161 | NULL, /* Contains DNS server IP address */ | |
162 | &pResult, /* Resource record that contains the response */ | |
163 | NULL); /* Reserved for future use */ | |
164 | ||
165 | if (status) return -1; | |
166 | else | |
167 | { | |
168 | for (pRec = pResult; pRec; pRec = pRec->pNext) | |
169 | { | |
170 | rrnum++; | |
171 | type = pRec->wType; | |
172 | ||
173 | if (rrtype != type && rrtype != ns_t_any) continue; | |
174 | ||
175 | switch (type) | |
176 | { | |
177 | case ns_t_txt: | |
178 | for (i=0; i < pRec->Data.TXT.dwStringCount; i++) | |
179 | { | |
180 | gotrec(rrnum, type, pRec->Data.TXT.pStringArray[i]); | |
181 | } | |
182 | break; | |
183 | ||
184 | case ns_t_a: | |
185 | gotrec(rrnum, type, (const char *)&pRec->Data.A.IpAddress); | |
186 | break; | |
187 | ||
188 | case ns_t_aaaa: | |
189 | gotrec(rrnum, type, (const char *)&pRec->Data.AAAA.Ip6Address); | |
190 | break; | |
191 | ||
192 | case ns_t_mx: | |
193 | gotrec(rrnum, type, pRec->Data.MX.pNameExchange); | |
194 | break; | |
195 | ||
196 | case ns_t_ns: | |
197 | gotrec(rrnum, type, pRec->Data.NS.pNameHost); | |
198 | break; | |
199 | } | |
200 | } | |
201 | } | |
202 | ||
203 | /* Free memory allocated for DNS records. */ | |
204 | DnsRecordListFree(pResult, DnsFreeRecordListDeep); | |
205 | ||
206 | return 0; | |
207 | } | |
208 | #endif | |
209 |