| 1 | #include <unistd.h> |
| 2 | #include "droproot.h" |
| 3 | #include "exit.h" |
| 4 | #include "env.h" |
| 5 | #include "uint32.h" |
| 6 | #include "uint16.h" |
| 7 | #include "ip4.h" |
| 8 | #include "tai.h" |
| 9 | #include "buffer.h" |
| 10 | #include "timeoutread.h" |
| 11 | #include "timeoutwrite.h" |
| 12 | #include "open.h" |
| 13 | #include "seek.h" |
| 14 | #include "cdb.h" |
| 15 | #include "stralloc.h" |
| 16 | #include "strerr.h" |
| 17 | #include "str.h" |
| 18 | #include "byte.h" |
| 19 | #include "case.h" |
| 20 | #include "dns.h" |
| 21 | #include "scan.h" |
| 22 | #include "qlog.h" |
| 23 | #include "response.h" |
| 24 | |
| 25 | extern int respond(char *,char *,char *); |
| 26 | |
| 27 | #define FATAL "axfrdns: fatal: " |
| 28 | |
| 29 | void nomem() |
| 30 | { |
| 31 | strerr_die2x(111,FATAL,"out of memory"); |
| 32 | } |
| 33 | void die_truncated() |
| 34 | { |
| 35 | strerr_die2x(111,FATAL,"truncated request"); |
| 36 | } |
| 37 | void die_netwrite() |
| 38 | { |
| 39 | strerr_die2sys(111,FATAL,"unable to write to network: "); |
| 40 | } |
| 41 | void die_netread() |
| 42 | { |
| 43 | strerr_die2sys(111,FATAL,"unable to read from network: "); |
| 44 | } |
| 45 | void die_outside() |
| 46 | { |
| 47 | strerr_die2x(111,FATAL,"unable to locate information in data.cdb"); |
| 48 | } |
| 49 | void die_cdbread() |
| 50 | { |
| 51 | strerr_die2sys(111,FATAL,"unable to read data.cdb: "); |
| 52 | } |
| 53 | void die_cdbformat() |
| 54 | { |
| 55 | strerr_die3x(111,FATAL,"unable to read data.cdb: ","format error"); |
| 56 | } |
| 57 | |
| 58 | int safewrite(int fd,char *buf,unsigned int len) |
| 59 | { |
| 60 | int w; |
| 61 | |
| 62 | w = timeoutwrite(60,fd,buf,len); |
| 63 | if (w <= 0) die_netwrite(); |
| 64 | return w; |
| 65 | } |
| 66 | |
| 67 | char netwritespace[1024]; |
| 68 | buffer netwrite = BUFFER_INIT(safewrite,1,netwritespace,sizeof netwritespace); |
| 69 | |
| 70 | void print(char *buf,unsigned int len) |
| 71 | { |
| 72 | char tcpheader[2]; |
| 73 | uint16_pack_big(tcpheader,len); |
| 74 | buffer_put(&netwrite,tcpheader,2); |
| 75 | buffer_put(&netwrite,buf,len); |
| 76 | buffer_flush(&netwrite); |
| 77 | } |
| 78 | |
| 79 | char *axfr; |
| 80 | static char *axfrok; |
| 81 | |
| 82 | void axfrcheck(char *q) |
| 83 | { |
| 84 | int i; |
| 85 | int j; |
| 86 | |
| 87 | if (!axfr) return; |
| 88 | |
| 89 | i = j = 0; |
| 90 | for (;;) { |
| 91 | if (!axfr[i] || (axfr[i] == '/')) { |
| 92 | if (i > j) { |
| 93 | if (!dns_domain_fromdot(&axfrok,axfr + j,i - j)) nomem(); |
| 94 | if (dns_domain_equal(q,axfrok)) return; |
| 95 | } |
| 96 | j = i + 1; |
| 97 | } |
| 98 | if (!axfr[i]) break; |
| 99 | ++i; |
| 100 | } |
| 101 | |
| 102 | strerr_die2x(111,FATAL,"disallowed zone transfer request"); |
| 103 | } |
| 104 | |
| 105 | static char *zone; |
| 106 | unsigned int zonelen; |
| 107 | char typeclass[4]; |
| 108 | |
| 109 | int fdcdb; |
| 110 | buffer bcdb; |
| 111 | char bcdbspace[1024]; |
| 112 | |
| 113 | void get(char *buf,unsigned int len) |
| 114 | { |
| 115 | int r; |
| 116 | |
| 117 | while (len > 0) { |
| 118 | r = buffer_get(&bcdb,buf,len); |
| 119 | if (r < 0) die_cdbread(); |
| 120 | if (!r) die_cdbformat(); |
| 121 | buf += r; |
| 122 | len -= r; |
| 123 | } |
| 124 | } |
| 125 | |
| 126 | char ip[4]; |
| 127 | unsigned long port; |
| 128 | char clientloc[2]; |
| 129 | |
| 130 | struct tai now; |
| 131 | char data[32767]; |
| 132 | uint32 dlen; |
| 133 | uint32 dpos; |
| 134 | |
| 135 | void copy(char *buf,unsigned int len) |
| 136 | { |
| 137 | dpos = dns_packet_copy(data,dlen,dpos,buf,len); |
| 138 | if (!dpos) die_cdbread(); |
| 139 | } |
| 140 | |
| 141 | void doname(stralloc *sa) |
| 142 | { |
| 143 | static char *d; |
| 144 | dpos = dns_packet_getname(data,dlen,dpos,&d); |
| 145 | if (!dpos) die_cdbread(); |
| 146 | if (!stralloc_catb(sa,d,dns_domain_length(d))) nomem(); |
| 147 | } |
| 148 | |
| 149 | int build(stralloc *sa,char *q,int flagsoa,char id[2]) |
| 150 | { |
| 151 | unsigned int rdatapos; |
| 152 | char misc[20]; |
| 153 | char type[2]; |
| 154 | char recordloc[2]; |
| 155 | char ttl[4]; |
| 156 | char ttd[8]; |
| 157 | struct tai cutoff; |
| 158 | |
| 159 | dpos = 0; |
| 160 | copy(type,2); |
| 161 | if (flagsoa) if (byte_diff(type,2,DNS_T_SOA)) return 0; |
| 162 | if (!flagsoa) if (byte_equal(type,2,DNS_T_SOA)) return 0; |
| 163 | |
| 164 | if (!stralloc_copyb(sa,id,2)) nomem(); |
| 165 | if (!stralloc_catb(sa,"\204\000\0\0\0\1\0\0\0\0",10)) nomem(); |
| 166 | copy(misc,1); |
| 167 | if ((misc[0] == '=' + 1) || (misc[0] == '*' + 1)) { |
| 168 | --misc[0]; |
| 169 | copy(recordloc,2); |
| 170 | if (byte_diff(recordloc,2,clientloc)) return 0; |
| 171 | } |
| 172 | if (misc[0] == '*') { |
| 173 | if (flagsoa) return 0; |
| 174 | if (!stralloc_catb(sa,"\1*",2)) nomem(); |
| 175 | } |
| 176 | if (!stralloc_catb(sa,q,dns_domain_length(q))) nomem(); |
| 177 | if (!stralloc_catb(sa,type,2)) nomem(); |
| 178 | |
| 179 | copy(ttl,4); |
| 180 | copy(ttd,8); |
| 181 | if (byte_diff(ttd,8,"\0\0\0\0\0\0\0\0")) { |
| 182 | tai_unpack(ttd,&cutoff); |
| 183 | if (byte_equal(ttl,4,"\0\0\0\0")) { |
| 184 | if (tai_less(&cutoff,&now)) return 0; |
| 185 | uint32_pack_big(ttl,2); |
| 186 | } |
| 187 | else |
| 188 | if (!tai_less(&cutoff,&now)) return 0; |
| 189 | } |
| 190 | |
| 191 | if (!stralloc_catb(sa,DNS_C_IN,2)) nomem(); |
| 192 | if (!stralloc_catb(sa,ttl,4)) nomem(); |
| 193 | if (!stralloc_catb(sa,"\0\0",2)) nomem(); |
| 194 | rdatapos = sa->len; |
| 195 | |
| 196 | if (byte_equal(type,2,DNS_T_SOA)) { |
| 197 | doname(sa); |
| 198 | doname(sa); |
| 199 | copy(misc,20); |
| 200 | if (!stralloc_catb(sa,misc,20)) nomem(); |
| 201 | } |
| 202 | else if (byte_equal(type,2,DNS_T_NS) || byte_equal(type,2,DNS_T_PTR) || byte_equal(type,2,DNS_T_CNAME)) { |
| 203 | doname(sa); |
| 204 | } |
| 205 | else if (byte_equal(type,2,DNS_T_MX)) { |
| 206 | copy(misc,2); |
| 207 | if (!stralloc_catb(sa,misc,2)) nomem(); |
| 208 | doname(sa); |
| 209 | } |
| 210 | else |
| 211 | if (!stralloc_catb(sa,data + dpos,dlen - dpos)) nomem(); |
| 212 | |
| 213 | if (sa->len > 65535) die_cdbformat(); |
| 214 | uint16_pack_big(sa->s + rdatapos - 2,sa->len - rdatapos); |
| 215 | return 1; |
| 216 | } |
| 217 | |
| 218 | static struct cdb c; |
| 219 | static char *q; |
| 220 | static stralloc soa; |
| 221 | static stralloc message; |
| 222 | |
| 223 | void doaxfr(char id[2]) |
| 224 | { |
| 225 | char key[512]; |
| 226 | uint32 klen; |
| 227 | char num[4]; |
| 228 | uint32 eod; |
| 229 | uint32 pos; |
| 230 | int r; |
| 231 | |
| 232 | axfrcheck(zone); |
| 233 | |
| 234 | tai_now(&now); |
| 235 | cdb_init(&c,fdcdb); |
| 236 | |
| 237 | byte_zero(clientloc,2); |
| 238 | key[0] = 0; |
| 239 | key[1] = '%'; |
| 240 | byte_copy(key + 2,4,ip); |
| 241 | r = cdb_find(&c,key,6); |
| 242 | if (!r) r = cdb_find(&c,key,5); |
| 243 | if (!r) r = cdb_find(&c,key,4); |
| 244 | if (!r) r = cdb_find(&c,key,3); |
| 245 | if (!r) r = cdb_find(&c,key,2); |
| 246 | if (r == -1) die_cdbread(); |
| 247 | if (r && (cdb_datalen(&c) == 2)) |
| 248 | if (cdb_read(&c,clientloc,2,cdb_datapos(&c)) == -1) die_cdbread(); |
| 249 | |
| 250 | cdb_findstart(&c); |
| 251 | for (;;) { |
| 252 | r = cdb_findnext(&c,zone,zonelen); |
| 253 | if (r == -1) die_cdbread(); |
| 254 | if (!r) die_outside(); |
| 255 | dlen = cdb_datalen(&c); |
| 256 | if (dlen > sizeof data) die_cdbformat(); |
| 257 | if (cdb_read(&c,data,dlen,cdb_datapos(&c)) == -1) die_cdbformat(); |
| 258 | if (build(&soa,zone,1,id)) break; |
| 259 | } |
| 260 | |
| 261 | cdb_free(&c); |
| 262 | print(soa.s,soa.len); |
| 263 | |
| 264 | seek_begin(fdcdb); |
| 265 | buffer_init(&bcdb,buffer_unixread,fdcdb,bcdbspace,sizeof bcdbspace); |
| 266 | |
| 267 | pos = 0; |
| 268 | get(num,4); pos += 4; |
| 269 | uint32_unpack(num,&eod); |
| 270 | while (pos < 2048) { get(num,4); pos += 4; } |
| 271 | |
| 272 | while (pos < eod) { |
| 273 | if (eod - pos < 8) die_cdbformat(); |
| 274 | get(num,4); pos += 4; |
| 275 | uint32_unpack(num,&klen); |
| 276 | get(num,4); pos += 4; |
| 277 | uint32_unpack(num,&dlen); |
| 278 | if (eod - pos < klen) die_cdbformat(); |
| 279 | pos += klen; |
| 280 | if (eod - pos < dlen) die_cdbformat(); |
| 281 | pos += dlen; |
| 282 | |
| 283 | if (klen > sizeof key) die_cdbformat(); |
| 284 | get(key,klen); |
| 285 | if (dlen > sizeof data) die_cdbformat(); |
| 286 | get(data,dlen); |
| 287 | |
| 288 | if ((klen > 1) && (key[0] == 0)) continue; /* location */ |
| 289 | if (klen < 1) die_cdbformat(); |
| 290 | if (dns_packet_getname(key,klen,0,&q) != klen) die_cdbformat(); |
| 291 | if (!dns_domain_suffix(q,zone)) continue; |
| 292 | if (!build(&message,q,0,id)) continue; |
| 293 | print(message.s,message.len); |
| 294 | } |
| 295 | |
| 296 | print(soa.s,soa.len); |
| 297 | } |
| 298 | |
| 299 | void netread(char *buf,unsigned int len) |
| 300 | { |
| 301 | int r; |
| 302 | |
| 303 | while (len > 0) { |
| 304 | r = timeoutread(60,0,buf,len); |
| 305 | if (r == 0) _exit(0); |
| 306 | if (r < 0) die_netread(); |
| 307 | buf += r; len -= r; |
| 308 | } |
| 309 | } |
| 310 | |
| 311 | char tcpheader[2]; |
| 312 | char buf[512]; |
| 313 | uint16 len; |
| 314 | |
| 315 | static char seed[128]; |
| 316 | |
| 317 | int main() |
| 318 | { |
| 319 | unsigned int pos; |
| 320 | char header[12]; |
| 321 | char qtype[2]; |
| 322 | char qclass[2]; |
| 323 | const char *x; |
| 324 | |
| 325 | droproot(FATAL); |
| 326 | dns_random_init(seed); |
| 327 | |
| 328 | axfr = env_get("AXFR"); |
| 329 | |
| 330 | x = env_get("TCPREMOTEIP"); |
| 331 | if (x && ip4_scan(x,ip)) |
| 332 | ; |
| 333 | else |
| 334 | byte_zero(ip,4); |
| 335 | |
| 336 | x = env_get("TCPREMOTEPORT"); |
| 337 | if (!x) x = "0"; |
| 338 | scan_ulong(x,&port); |
| 339 | |
| 340 | for (;;) { |
| 341 | netread(tcpheader,2); |
| 342 | uint16_unpack_big(tcpheader,&len); |
| 343 | if (len > 512) strerr_die2x(111,FATAL,"excessively large request"); |
| 344 | netread(buf,len); |
| 345 | |
| 346 | pos = dns_packet_copy(buf,len,0,header,12); if (!pos) die_truncated(); |
| 347 | if (header[2] & 254) strerr_die2x(111,FATAL,"bogus query"); |
| 348 | if (header[4] || (header[5] != 1)) strerr_die2x(111,FATAL,"bogus query"); |
| 349 | |
| 350 | pos = dns_packet_getname(buf,len,pos,&zone); if (!pos) die_truncated(); |
| 351 | zonelen = dns_domain_length(zone); |
| 352 | pos = dns_packet_copy(buf,len,pos,qtype,2); if (!pos) die_truncated(); |
| 353 | pos = dns_packet_copy(buf,len,pos,qclass,2); if (!pos) die_truncated(); |
| 354 | |
| 355 | if (byte_diff(qclass,2,DNS_C_IN) && byte_diff(qclass,2,DNS_C_ANY)) |
| 356 | strerr_die2x(111,FATAL,"bogus query: bad class"); |
| 357 | |
| 358 | qlog(ip,port,header,zone,qtype," "); |
| 359 | |
| 360 | if (byte_equal(qtype,2,DNS_T_AXFR)) { |
| 361 | case_lowerb(zone,zonelen); |
| 362 | fdcdb = open_read("data.cdb"); |
| 363 | if (fdcdb == -1) die_cdbread(); |
| 364 | doaxfr(header); |
| 365 | close(fdcdb); |
| 366 | } |
| 367 | else { |
| 368 | if (!response_query(zone,qtype,qclass)) nomem(); |
| 369 | response[2] |= 4; |
| 370 | case_lowerb(zone,zonelen); |
| 371 | response_id(header); |
| 372 | response[3] &= ~128; |
| 373 | if (!(header[2] & 1)) response[2] &= ~1; |
| 374 | if (!respond(zone,qtype,ip)) die_outside(); |
| 375 | print(response,response_len); |
| 376 | } |
| 377 | } |
| 378 | } |