| 1 | #include <stdio.h> |
| 2 | #include <netdb.h> |
| 3 | #include <sys/types.h> |
| 4 | #include <netinet/in.h> |
| 5 | #include <arpa/nameser.h> |
| 6 | #include <resolv.h> |
| 7 | #include <errno.h> |
| 8 | extern int res_query(); |
| 9 | extern int res_search(); |
| 10 | extern int errno; |
| 11 | extern int h_errno; |
| 12 | #include "ip.h" |
| 13 | #include "ipalloc.h" |
| 14 | #include "fmt.h" |
| 15 | #include "alloc.h" |
| 16 | #include "str.h" |
| 17 | #include "stralloc.h" |
| 18 | #include "dns.h" |
| 19 | #include "case.h" |
| 20 | |
| 21 | static unsigned short getshort(c) unsigned char *c; |
| 22 | { unsigned short u; u = c[0]; return (u << 8) + c[1]; } |
| 23 | |
| 24 | static union { HEADER hdr; unsigned char buf[PACKETSZ]; } response; |
| 25 | static int responselen; |
| 26 | static unsigned char *responseend; |
| 27 | static unsigned char *responsepos; |
| 28 | |
| 29 | static int numanswers; |
| 30 | static char name[MAXDNAME]; |
| 31 | static struct ip_address ip; |
| 32 | unsigned short pref; |
| 33 | |
| 34 | static stralloc glue = {0}; |
| 35 | |
| 36 | static int (*lookup)() = res_query; |
| 37 | |
| 38 | static int resolve(domain,type) |
| 39 | stralloc *domain; |
| 40 | int type; |
| 41 | { |
| 42 | int n; |
| 43 | int i; |
| 44 | |
| 45 | errno = 0; |
| 46 | if (!stralloc_copy(&glue,domain)) return DNS_MEM; |
| 47 | if (!stralloc_0(&glue)) return DNS_MEM; |
| 48 | responselen = lookup(glue.s,C_IN,type,response.buf,sizeof(response)); |
| 49 | if (responselen <= 0) |
| 50 | { |
| 51 | if (errno == ECONNREFUSED) return DNS_SOFT; |
| 52 | if (h_errno == TRY_AGAIN) return DNS_SOFT; |
| 53 | return DNS_HARD; |
| 54 | } |
| 55 | if (responselen >= sizeof(response)) |
| 56 | responselen = sizeof(response); |
| 57 | responseend = response.buf + responselen; |
| 58 | responsepos = response.buf + sizeof(HEADER); |
| 59 | n = ntohs(response.hdr.qdcount); |
| 60 | while (n-- > 0) |
| 61 | { |
| 62 | i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME); |
| 63 | if (i < 0) return DNS_SOFT; |
| 64 | responsepos += i; |
| 65 | i = responseend - responsepos; |
| 66 | if (i < QFIXEDSZ) return DNS_SOFT; |
| 67 | responsepos += QFIXEDSZ; |
| 68 | } |
| 69 | numanswers = ntohs(response.hdr.ancount); |
| 70 | return 0; |
| 71 | } |
| 72 | |
| 73 | static int findname(wanttype) |
| 74 | int wanttype; |
| 75 | { |
| 76 | unsigned short rrtype; |
| 77 | unsigned short rrdlen; |
| 78 | int i; |
| 79 | |
| 80 | if (numanswers <= 0) return 2; |
| 81 | --numanswers; |
| 82 | if (responsepos == responseend) return DNS_SOFT; |
| 83 | |
| 84 | i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME); |
| 85 | if (i < 0) return DNS_SOFT; |
| 86 | responsepos += i; |
| 87 | |
| 88 | i = responseend - responsepos; |
| 89 | if (i < 4 + 3 * 2) return DNS_SOFT; |
| 90 | |
| 91 | rrtype = getshort(responsepos); |
| 92 | rrdlen = getshort(responsepos + 8); |
| 93 | responsepos += 10; |
| 94 | |
| 95 | if (rrtype == wanttype) |
| 96 | { |
| 97 | if (dn_expand(response.buf,responseend,responsepos,name,MAXDNAME) < 0) |
| 98 | return DNS_SOFT; |
| 99 | responsepos += rrdlen; |
| 100 | return 1; |
| 101 | } |
| 102 | |
| 103 | responsepos += rrdlen; |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | static int findip(wanttype) |
| 108 | int wanttype; |
| 109 | { |
| 110 | unsigned short rrtype; |
| 111 | unsigned short rrdlen; |
| 112 | int i; |
| 113 | |
| 114 | if (numanswers <= 0) return 2; |
| 115 | --numanswers; |
| 116 | if (responsepos == responseend) return DNS_SOFT; |
| 117 | |
| 118 | i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME); |
| 119 | if (i < 0) return DNS_SOFT; |
| 120 | responsepos += i; |
| 121 | |
| 122 | i = responseend - responsepos; |
| 123 | if (i < 4 + 3 * 2) return DNS_SOFT; |
| 124 | |
| 125 | rrtype = getshort(responsepos); |
| 126 | rrdlen = getshort(responsepos + 8); |
| 127 | responsepos += 10; |
| 128 | |
| 129 | if (rrtype == wanttype) |
| 130 | { |
| 131 | if (rrdlen < 4) |
| 132 | return DNS_SOFT; |
| 133 | ip.d[0] = responsepos[0]; |
| 134 | ip.d[1] = responsepos[1]; |
| 135 | ip.d[2] = responsepos[2]; |
| 136 | ip.d[3] = responsepos[3]; |
| 137 | responsepos += rrdlen; |
| 138 | return 1; |
| 139 | } |
| 140 | |
| 141 | responsepos += rrdlen; |
| 142 | return 0; |
| 143 | } |
| 144 | |
| 145 | static int findmx(wanttype) |
| 146 | int wanttype; |
| 147 | { |
| 148 | unsigned short rrtype; |
| 149 | unsigned short rrdlen; |
| 150 | int i; |
| 151 | |
| 152 | if (numanswers <= 0) return 2; |
| 153 | --numanswers; |
| 154 | if (responsepos == responseend) return DNS_SOFT; |
| 155 | |
| 156 | i = dn_expand(response.buf,responseend,responsepos,name,MAXDNAME); |
| 157 | if (i < 0) return DNS_SOFT; |
| 158 | responsepos += i; |
| 159 | |
| 160 | i = responseend - responsepos; |
| 161 | if (i < 4 + 3 * 2) return DNS_SOFT; |
| 162 | |
| 163 | rrtype = getshort(responsepos); |
| 164 | rrdlen = getshort(responsepos + 8); |
| 165 | responsepos += 10; |
| 166 | |
| 167 | if (rrtype == wanttype) |
| 168 | { |
| 169 | if (rrdlen < 3) |
| 170 | return DNS_SOFT; |
| 171 | pref = (responsepos[0] << 8) + responsepos[1]; |
| 172 | if (dn_expand(response.buf,responseend,responsepos + 2,name,MAXDNAME) < 0) |
| 173 | return DNS_SOFT; |
| 174 | responsepos += rrdlen; |
| 175 | return 1; |
| 176 | } |
| 177 | |
| 178 | responsepos += rrdlen; |
| 179 | return 0; |
| 180 | } |
| 181 | |
| 182 | void dns_init(flagsearch) |
| 183 | int flagsearch; |
| 184 | { |
| 185 | res_init(); |
| 186 | if (flagsearch) lookup = res_search; |
| 187 | } |
| 188 | |
| 189 | int dns_cname(sa) |
| 190 | stralloc *sa; |
| 191 | { |
| 192 | int r; |
| 193 | int loop; |
| 194 | for (loop = 0;loop < 10;++loop) |
| 195 | { |
| 196 | if (!sa->len) return loop; |
| 197 | if (sa->s[sa->len - 1] == ']') return loop; |
| 198 | if (sa->s[sa->len - 1] == '.') { --sa->len; continue; } |
| 199 | switch(resolve(sa,T_ANY)) |
| 200 | { |
| 201 | case DNS_MEM: return DNS_MEM; |
| 202 | case DNS_SOFT: return DNS_SOFT; |
| 203 | case DNS_HARD: return loop; |
| 204 | default: |
| 205 | while ((r = findname(T_CNAME)) != 2) |
| 206 | { |
| 207 | if (r == DNS_SOFT) return DNS_SOFT; |
| 208 | if (r == 1) |
| 209 | { |
| 210 | if (!stralloc_copys(sa,name)) return DNS_MEM; |
| 211 | break; |
| 212 | } |
| 213 | } |
| 214 | if (r == 2) return loop; |
| 215 | } |
| 216 | } |
| 217 | return DNS_HARD; /* alias loop */ |
| 218 | } |
| 219 | |
| 220 | #define FMT_IAA 40 |
| 221 | |
| 222 | static int iaafmt(s,ip) |
| 223 | char *s; |
| 224 | struct ip_address *ip; |
| 225 | { |
| 226 | unsigned int i; |
| 227 | unsigned int len; |
| 228 | len = 0; |
| 229 | i = fmt_ulong(s,(unsigned long) ip->d[3]); len += i; if (s) s += i; |
| 230 | i = fmt_str(s,"."); len += i; if (s) s += i; |
| 231 | i = fmt_ulong(s,(unsigned long) ip->d[2]); len += i; if (s) s += i; |
| 232 | i = fmt_str(s,"."); len += i; if (s) s += i; |
| 233 | i = fmt_ulong(s,(unsigned long) ip->d[1]); len += i; if (s) s += i; |
| 234 | i = fmt_str(s,"."); len += i; if (s) s += i; |
| 235 | i = fmt_ulong(s,(unsigned long) ip->d[0]); len += i; if (s) s += i; |
| 236 | i = fmt_str(s,".in-addr.arpa."); len += i; if (s) s += i; |
| 237 | return len; |
| 238 | } |
| 239 | |
| 240 | int dns_ptr(sa,ip) |
| 241 | stralloc *sa; |
| 242 | struct ip_address *ip; |
| 243 | { |
| 244 | int r; |
| 245 | |
| 246 | if (!stralloc_ready(sa,iaafmt((char *) 0,ip))) return DNS_MEM; |
| 247 | sa->len = iaafmt(sa->s,ip); |
| 248 | switch(resolve(sa,T_PTR)) |
| 249 | { |
| 250 | case DNS_MEM: return DNS_MEM; |
| 251 | case DNS_SOFT: return DNS_SOFT; |
| 252 | case DNS_HARD: return DNS_HARD; |
| 253 | } |
| 254 | while ((r = findname(T_PTR)) != 2) |
| 255 | { |
| 256 | if (r == DNS_SOFT) return DNS_SOFT; |
| 257 | if (r == 1) |
| 258 | { |
| 259 | if (!stralloc_copys(sa,name)) return DNS_MEM; |
| 260 | return 0; |
| 261 | } |
| 262 | } |
| 263 | return DNS_HARD; |
| 264 | } |
| 265 | |
| 266 | static int dns_ipplus(ia,sa,pref) |
| 267 | ipalloc *ia; |
| 268 | stralloc *sa; |
| 269 | int pref; |
| 270 | { |
| 271 | int r; |
| 272 | struct ip_mx ix; |
| 273 | |
| 274 | if (!stralloc_copy(&glue,sa)) return DNS_MEM; |
| 275 | if (!stralloc_0(&glue)) return DNS_MEM; |
| 276 | if (glue.s[0]) { |
| 277 | ix.pref = 0; |
| 278 | if (!glue.s[ip_scan(glue.s,&ix.ip)] || !glue.s[ip_scanbracket(glue.s,&ix.ip)]) |
| 279 | { |
| 280 | if (!ipalloc_append(ia,&ix)) return DNS_MEM; |
| 281 | return 0; |
| 282 | } |
| 283 | } |
| 284 | |
| 285 | switch(resolve(sa,T_A)) |
| 286 | { |
| 287 | case DNS_MEM: return DNS_MEM; |
| 288 | case DNS_SOFT: return DNS_SOFT; |
| 289 | case DNS_HARD: return DNS_HARD; |
| 290 | } |
| 291 | while ((r = findip(T_A)) != 2) |
| 292 | { |
| 293 | ix.ip = ip; |
| 294 | ix.pref = pref; |
| 295 | if (r == DNS_SOFT) return DNS_SOFT; |
| 296 | if (r == 1) |
| 297 | if (!ipalloc_append(ia,&ix)) return DNS_MEM; |
| 298 | } |
| 299 | return 0; |
| 300 | } |
| 301 | |
| 302 | int dns_ip(ia,sa) |
| 303 | ipalloc *ia; |
| 304 | stralloc *sa; |
| 305 | { |
| 306 | if (!ipalloc_readyplus(ia,0)) return DNS_MEM; |
| 307 | ia->len = 0; |
| 308 | return dns_ipplus(ia,sa,0); |
| 309 | } |
| 310 | |
| 311 | int dns_mxip(ia,sa,random) |
| 312 | ipalloc *ia; |
| 313 | stralloc *sa; |
| 314 | unsigned long random; |
| 315 | { |
| 316 | int r; |
| 317 | struct mx { stralloc sa; unsigned short p; } *mx; |
| 318 | struct ip_mx ix; |
| 319 | int nummx; |
| 320 | int i; |
| 321 | int j; |
| 322 | int flagsoft; |
| 323 | |
| 324 | if (!ipalloc_readyplus(ia,0)) return DNS_MEM; |
| 325 | ia->len = 0; |
| 326 | |
| 327 | if (!stralloc_copy(&glue,sa)) return DNS_MEM; |
| 328 | if (!stralloc_0(&glue)) return DNS_MEM; |
| 329 | if (glue.s[0]) { |
| 330 | ix.pref = 0; |
| 331 | if (!glue.s[ip_scan(glue.s,&ix.ip)] || !glue.s[ip_scanbracket(glue.s,&ix.ip)]) |
| 332 | { |
| 333 | if (!ipalloc_append(ia,&ix)) return DNS_MEM; |
| 334 | return 0; |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | switch(resolve(sa,T_MX)) |
| 339 | { |
| 340 | case DNS_MEM: return DNS_MEM; |
| 341 | case DNS_SOFT: return DNS_SOFT; |
| 342 | case DNS_HARD: return dns_ip(ia,sa); |
| 343 | } |
| 344 | |
| 345 | mx = (struct mx *) alloc(numanswers * sizeof(struct mx)); |
| 346 | if (!mx) return DNS_MEM; |
| 347 | nummx = 0; |
| 348 | |
| 349 | while ((r = findmx(T_MX)) != 2) |
| 350 | { |
| 351 | if (r == DNS_SOFT) { alloc_free(mx); return DNS_SOFT; } |
| 352 | if (r == 1) |
| 353 | { |
| 354 | mx[nummx].p = pref; |
| 355 | mx[nummx].sa.s = 0; |
| 356 | if (!stralloc_copys(&mx[nummx].sa,name)) |
| 357 | { |
| 358 | while (nummx > 0) alloc_free(mx[--nummx].sa.s); |
| 359 | alloc_free(mx); return DNS_MEM; |
| 360 | } |
| 361 | ++nummx; |
| 362 | } |
| 363 | } |
| 364 | |
| 365 | if (!nummx) return dns_ip(ia,sa); /* e.g., CNAME -> A */ |
| 366 | |
| 367 | flagsoft = 0; |
| 368 | while (nummx > 0) |
| 369 | { |
| 370 | unsigned long numsame; |
| 371 | |
| 372 | i = 0; |
| 373 | numsame = 1; |
| 374 | for (j = 1;j < nummx;++j) |
| 375 | if (mx[j].p < mx[i].p) |
| 376 | { |
| 377 | i = j; |
| 378 | numsame = 1; |
| 379 | } |
| 380 | else if (mx[j].p == mx[i].p) |
| 381 | { |
| 382 | ++numsame; |
| 383 | random = random * 69069 + 1; |
| 384 | if ((random / 2) < (2147483647 / numsame)) |
| 385 | i = j; |
| 386 | } |
| 387 | |
| 388 | switch(dns_ipplus(ia,&mx[i].sa,mx[i].p)) |
| 389 | { |
| 390 | case DNS_MEM: case DNS_SOFT: |
| 391 | flagsoft = 1; break; |
| 392 | } |
| 393 | |
| 394 | alloc_free(mx[i].sa.s); |
| 395 | mx[i] = mx[--nummx]; |
| 396 | } |
| 397 | |
| 398 | alloc_free(mx); |
| 399 | return flagsoft; |
| 400 | } |