source/libaddns/dnssock.c

   1 /*
   2   Linux DNS client library implementation
   3
   4   Copyright (C) 2006 Krishna Ganugapati <krishnag@centeris.com>
   5   Copyright (C) 2006 Gerald Carter <jerry@samba.org>
   6
   7      ** NOTE! The following LGPL license applies to the libaddns
   8      ** library. This does NOT imply that all of Samba is released
   9      ** under the LGPL
  10
  11   This library is free software; you can redistribute it and/or
  12   modify it under the terms of the GNU Lesser General Public
  13   License as published by the Free Software Foundation; either
  14   version 2.1 of the License, or (at your option) any later version.
  15
  16   This library is distributed in the hope that it will be useful,
  17   but WITHOUT ANY WARRANTY; without even the implied warranty of
  18   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19   Lesser General Public License for more details.
  20
  21   You should have received a copy of the GNU Lesser General Public
  22   License along with this library; if not, see <http://www.gnu.org/licenses/>.
  23 */
  24
  25 #include "dns.h"
  26 #include <sys/time.h>
  27 #include <unistd.h>
  28
  29 static int destroy_dns_connection(struct dns_connection *conn)
  30 {
  31         return close(conn->s);
  32 }
  33
  34 /********************************************************************
  35 ********************************************************************/
  36
  37 static DNS_ERROR dns_tcp_open( const char *nameserver,
  38                                TALLOC_CTX *mem_ctx,
  39                                struct dns_connection **result )
  40 {
  41         uint32_t ulAddress;
  42         struct hostent *pHost;
  43         struct sockaddr_in s_in;
  44         struct dns_connection *conn;
  45         int res;
  46
  47         if (!(conn = talloc(mem_ctx, struct dns_connection))) {
  48                 return ERROR_DNS_NO_MEMORY;
  49         }
  50
  51         if ( (ulAddress = inet_addr( nameserver )) == INADDR_NONE ) {
  52                 if ( (pHost = gethostbyname( nameserver )) == NULL ) {
  53                         TALLOC_FREE(conn);
  54                         return ERROR_DNS_INVALID_NAME_SERVER;
  55                 }
  56                 memcpy( &ulAddress, pHost->h_addr, pHost->h_length );
  57         }
  58
  59         conn->s = socket( PF_INET, SOCK_STREAM, 0 );
  60         if (conn->s == -1) {
  61                 TALLOC_FREE(conn);
  62                 return ERROR_DNS_CONNECTION_FAILED;
  63         }
  64
  65         talloc_set_destructor(conn, destroy_dns_connection);
  66
  67         s_in.sin_family = AF_INET;
  68         s_in.sin_addr.s_addr = ulAddress;
  69         s_in.sin_port = htons( DNS_TCP_PORT );
  70
  71         res = connect(conn->s, (struct sockaddr*)&s_in, sizeof( s_in ));
  72         if (res == -1) {
  73                 TALLOC_FREE(conn);
  74                 return ERROR_DNS_CONNECTION_FAILED;
  75         }
  76
  77         conn->hType = DNS_TCP;
  78
  79         *result = conn;
  80         return ERROR_DNS_SUCCESS;
  81 }
  82
  83 /********************************************************************
  84 ********************************************************************/
  85
  86 static DNS_ERROR dns_udp_open( const char *nameserver,
  87                                TALLOC_CTX *mem_ctx,
  88                                struct dns_connection **result )
  89 {
  90         unsigned long ulAddress;
  91         struct hostent *pHost;
  92         struct sockaddr_in RecvAddr;
  93         struct dns_connection *conn;
  94
  95         if (!(conn = talloc(NULL, struct dns_connection))) {
  96                 return ERROR_DNS_NO_MEMORY;
  97         }
  98
  99         if ( (ulAddress = inet_addr( nameserver )) == INADDR_NONE ) {
 100                 if ( (pHost = gethostbyname( nameserver )) == NULL ) {
 101                         TALLOC_FREE(conn);
 102                         return ERROR_DNS_INVALID_NAME_SERVER;
 103                 }
 104                 memcpy( &ulAddress, pHost->h_addr, pHost->h_length );
 105         }
 106
 107         /* Create a socket for sending data */
 108
 109         conn->s = socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
 110         if (conn->s == -1) {
 111                 TALLOC_FREE(conn);
 112                 return ERROR_DNS_CONNECTION_FAILED;
 113         }
 114
 115         talloc_set_destructor(conn, destroy_dns_connection);
 116
 117         /* Set up the RecvAddr structure with the IP address of
 118            the receiver (in this example case "123.456.789.1")
 119            and the specified port number. */
 120
 121         ZERO_STRUCT(RecvAddr);
 122         RecvAddr.sin_family = AF_INET;
 123         RecvAddr.sin_port = htons( DNS_UDP_PORT );
 124         RecvAddr.sin_addr.s_addr = ulAddress;
 125
 126         conn->hType = DNS_UDP;
 127         memcpy( &conn->RecvAddr, &RecvAddr, sizeof( struct sockaddr_in ) );
 128
 129         *result = conn;
 130         return ERROR_DNS_SUCCESS;
 131 }
 132
 133 /********************************************************************
 134 ********************************************************************/
 135
 136 DNS_ERROR dns_open_connection( const char *nameserver, int32 dwType,
 137                     TALLOC_CTX *mem_ctx,
 138                     struct dns_connection **conn )
 139 {
 140         switch ( dwType ) {
 141         case DNS_TCP:
 142                 return dns_tcp_open( nameserver, mem_ctx, conn );
 143         case DNS_UDP:
 144                 return dns_udp_open( nameserver, mem_ctx, conn );
 145         }
 146
 147         return ERROR_DNS_INVALID_PARAMETER;
 148 }
 149
 150 static DNS_ERROR write_all(int fd, uint8 *data, size_t len)
 151 {
 152         size_t total = 0;
 153
 154         while (total < len) {
 155
 156                 ssize_t ret = write(fd, data + total, len - total);
 157
 158                 if (ret <= 0) {
 159                         /*
 160                          * EOF or error
 161                          */
 162                         return ERROR_DNS_SOCKET_ERROR;
 163                 }
 164
 165                 total += ret;
 166         }
 167
 168         return ERROR_DNS_SUCCESS;
 169 }
 170
 171 static DNS_ERROR dns_send_tcp(struct dns_connection *conn,
 172                               const struct dns_buffer *buf)
 173 {
 174         uint16 len = htons(buf->offset);
 175         DNS_ERROR err;
 176
 177         err = write_all(conn->s, (uint8 *)&len, sizeof(len));
 178         if (!ERR_DNS_IS_OK(err)) return err;
 179
 180         return write_all(conn->s, buf->data, buf->offset);
 181 }
 182
 183 static DNS_ERROR dns_send_udp(struct dns_connection *conn,
 184                               const struct dns_buffer *buf)
 185 {
 186         ssize_t ret;
 187
 188         ret = sendto(conn->s, buf->data, buf->offset, 0,
 189                      (struct sockaddr *)&conn->RecvAddr,
 190                      sizeof(conn->RecvAddr));
 191
 192         if (ret != buf->offset) {
 193                 return ERROR_DNS_SOCKET_ERROR;
 194         }
 195
 196         return ERROR_DNS_SUCCESS;
 197 }
 198
 199 DNS_ERROR dns_send(struct dns_connection *conn, const struct dns_buffer *buf)
 200 {
 201         if (conn->hType == DNS_TCP) {
 202                 return dns_send_tcp(conn, buf);
 203         }
 204
 205         if (conn->hType == DNS_UDP) {
 206                 return dns_send_udp(conn, buf);
 207         }
 208
 209         return ERROR_DNS_INVALID_PARAMETER;
 210 }
 211
 212 static DNS_ERROR read_all(int fd, uint8 *data, size_t len)
 213 {
 214         size_t total = 0;
 215         fd_set rfds;
 216         struct timeval tv;
 217
 218         while (total < len) {
 219                 ssize_t ret;
 220                 int fd_ready;
 221
 222                 if (fd < 0 || fd >= FD_SETSIZE) {
 223                         return ERROR_DNS_SOCKET_ERROR;
 224                 }
 225
 226                 FD_ZERO( &rfds );
 227                 FD_SET( fd, &rfds );
 228
 229                 /* 10 second timeout */
 230                 tv.tv_sec = 10;
 231                 tv.tv_usec = 0;
 232
 233                 fd_ready = select( fd+1, &rfds, NULL, NULL, &tv );
 234                 if ( fd_ready == 0 ) {
 235                         /* read timeout */
 236                         return ERROR_DNS_SOCKET_ERROR;
 237                 }
 238
 239                 ret = read(fd, data + total, len - total);
 240                 if (ret <= 0) {
 241                         /* EOF or error */
 242                         return ERROR_DNS_SOCKET_ERROR;
 243                 }
 244
 245                 total += ret;
 246         }
 247
 248         return ERROR_DNS_SUCCESS;
 249 }
 250
 251 static DNS_ERROR dns_receive_tcp(TALLOC_CTX *mem_ctx,
 252                                  struct dns_connection *conn,
 253                                  struct dns_buffer **presult)
 254 {
 255         struct dns_buffer *buf;
 256         DNS_ERROR err;
 257         uint16 len;
 258
 259         if (!(buf = TALLOC_ZERO_P(mem_ctx, struct dns_buffer))) {
 260                 return ERROR_DNS_NO_MEMORY;
 261         }
 262
 263         err = read_all(conn->s, (uint8 *)&len, sizeof(len));
 264         if (!ERR_DNS_IS_OK(err)) {
 265                 return err;
 266         }
 267
 268         buf->size = ntohs(len);
 269
 270         if (buf->size) {
 271                 if (!(buf->data = TALLOC_ARRAY(buf, uint8, buf->size))) {
 272                         TALLOC_FREE(buf);
 273                         return ERROR_DNS_NO_MEMORY;
 274                 }
 275         } else {
 276                 buf->data = NULL;
 277         }
 278
 279         err = read_all(conn->s, buf->data, buf->size);
 280         if (!ERR_DNS_IS_OK(err)) {
 281                 TALLOC_FREE(buf);
 282                 return err;
 283         }
 284
 285         *presult = buf;
 286         return ERROR_DNS_SUCCESS;
 287 }
 288
 289 static DNS_ERROR dns_receive_udp(TALLOC_CTX *mem_ctx,
 290                                  struct dns_connection *conn,
 291                                  struct dns_buffer **presult)
 292 {
 293         struct dns_buffer *buf;
 294         ssize_t received;
 295
 296         if (!(buf = TALLOC_ZERO_P(mem_ctx, struct dns_buffer))) {
 297                 return ERROR_DNS_NO_MEMORY;
 298         }
 299
 300         /*
 301          * UDP based DNS can only be 512 bytes
 302          */
 303
 304         if (!(buf->data = TALLOC_ARRAY(buf, uint8, 512))) {
 305                 TALLOC_FREE(buf);
 306                 return ERROR_DNS_NO_MEMORY;
 307         }
 308
 309         received = recv(conn->s, (void *)buf->data, 512, 0);
 310
 311         if (received == -1) {
 312                 TALLOC_FREE(buf);
 313                 return ERROR_DNS_SOCKET_ERROR;
 314         }
 315
 316         if (received > 512) {
 317                 TALLOC_FREE(buf);
 318                 return ERROR_DNS_BAD_RESPONSE;
 319         }
 320
 321         buf->size = received;
 322         buf->offset = 0;
 323
 324         *presult = buf;
 325         return ERROR_DNS_SUCCESS;
 326 }
 327
 328 DNS_ERROR dns_receive(TALLOC_CTX *mem_ctx, struct dns_connection *conn,
 329                       struct dns_buffer **presult)
 330 {
 331         if (conn->hType == DNS_TCP) {
 332                 return dns_receive_tcp(mem_ctx, conn, presult);
 333         }
 334
 335         if (conn->hType == DNS_UDP) {
 336                 return dns_receive_udp(mem_ctx, conn, presult);
 337         }
 338
 339         return ERROR_DNS_INVALID_PARAMETER;
 340 }
 341
 342 DNS_ERROR dns_transaction(TALLOC_CTX *mem_ctx, struct dns_connection *conn,
 343                           const struct dns_request *req,
 344                           struct dns_request **resp)
 345 {
 346         struct dns_buffer *buf = NULL;
 347         DNS_ERROR err;
 348
 349         err = dns_marshall_request(conn, req, &buf);
 350         if (!ERR_DNS_IS_OK(err)) goto error;
 351
 352         err = dns_send(conn, buf);
 353         if (!ERR_DNS_IS_OK(err)) goto error;
 354         TALLOC_FREE(buf);
 355
 356         err = dns_receive(mem_ctx, conn, &buf);
 357         if (!ERR_DNS_IS_OK(err)) goto error;
 358
 359         err = dns_unmarshall_request(mem_ctx, buf, resp);
 360
 361  error:
 362         TALLOC_FREE(buf);
 363         return err;
 364 }
 365
 366 DNS_ERROR dns_update_transaction(TALLOC_CTX *mem_ctx,
 367                                  struct dns_connection *conn,
 368                                  struct dns_update_request *up_req,
 369                                  struct dns_update_request **up_resp)
 370 {
 371         struct dns_request *resp;
 372         DNS_ERROR err;
 373
 374         err = dns_transaction(mem_ctx, conn, dns_update2request(up_req),
 375                               &resp);
 376
 377         if (!ERR_DNS_IS_OK(err)) return err;
 378
 379         *up_resp = dns_request2update(resp);
 380         return ERROR_DNS_SUCCESS;
 381 }