src/connection.c

   1 /*
   2  * Handle connections.
   3  *
   4  * Copyright (C) 2011-2013  Simon Ruderich
   5  *
   6  * This program is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "tlsproxy.h"
  21 #include "connection.h"
  22 #include "verify.h"
  23
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <limits.h>
  27 #include <netdb.h>
  28 #include <poll.h>
  29 #include <unistd.h>
  30
  31 #include <gnutls/x509.h>
  32
  33
  34 /* Maximum length of a HTTP request line. Longer request lines are aborted
  35  * with an error. The standard doesn't specify a maximum line length but this
  36  * should be a good limit to make processing simpler. As HTTPS is used this
  37  * doesn't limit long GET requests. */
  38 #define MAX_REQUEST_LINE 4096
  39
  40 /* Format string used to send HTTP/1.0 error responses to the client.
  41  *
  42  * %s is used 5 times, first is the error code, then additional headers, next
  43  * two are the error code (no %n$s!), the last is the message. */
  44 #define HTTP_RESPONSE_FORMAT "HTTP/1.0 %s\r\n\
  45 Content-Type: text/html; charset=US-ASCII\r\n\
  46 %s\r\n\
  47 <!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n\
  48 <html>\n\
  49 <head><title>%s</title></head>\n\
  50 <body>\n\
  51 <h1>%s</h1>\n\
  52 <p>%s</p>\n\
  53 </body>\n\
  54 </html>\n"
  55
  56
  57 static int initialize_tls_session_client(int peer_socket,
  58         const char *hostname,
  59         gnutls_session_t *session,
  60         gnutls_certificate_credentials_t *x509_cred);
  61 static int initialize_tls_session_server(int peer_socket,
  62         gnutls_session_t *session,
  63         gnutls_certificate_credentials_t *x509_cred);
  64 static int initialize_tls_session_both(unsigned int flags,
  65         int peer_socket,
  66         gnutls_session_t *session,
  67         gnutls_certificate_credentials_t *x509_cred);
  68
  69 static int fdopen_read_write(int socket, FILE **read_fd, FILE **write_fd);
  70 static int read_http_request(FILE *client_fd, char *request, size_t length);
  71 static void send_bad_request(FILE *client_fd);
  72 static void send_authentication_required(FILE *client_fd);
  73 static void send_forwarding_failure(FILE *client_fd);
  74 static void tls_send_invalid_cert_message(gnutls_session_t session);
  75
  76 static void transfer_data(int client, int server);
  77 static int read_from_write_to(int from, int to);
  78 static void transfer_data_tls(int client, int server,
  79                               gnutls_session_t client_session,
  80                               gnutls_session_t server_session);
  81 static int read_from_write_to_tls(gnutls_session_t from, gnutls_session_t to,
  82                                   size_t buffer_size);
  83
  84 static int connect_to_host(const char *hostname, const char *port);
  85
  86 static int parse_request(const char *buffer, char *host, char *port,
  87                                              int *version_minor);
  88
  89 static void log_session_information(gnutls_session_t session);
  90
  91
  92 void handle_connection(int client_socket) {
  93     int server_socket;
  94     FILE *client_fd_read, *client_fd_write, *server_fd_read, *server_fd_write;
  95
  96     char buffer[MAX_REQUEST_LINE];
  97     char host[MAX_REQUEST_LINE];
  98     char port[5 + 1];
  99
 100     int version_minor; /* x in HTTP/1.x */
 101     int result;
 102
 103     /* client_x509_cred is used when talking to the client (acting as a TSL
 104      * server), server_x509_cred is used when talking to the server (acting as
 105      * a TSL client). */
 106     gnutls_certificate_credentials_t client_x509_cred, server_x509_cred;
 107
 108     gnutls_session_t client_session, server_session;
 109     /* initialize_tls_session_*() called? - used for goto out */
 110     int client_session_init, server_session_init;
 111     /* gnutls_handshake() called? - used for goto out */
 112     int client_session_started, server_session_started;
 113     /* Validation failed? If yes we need to send the special "invalid"
 114      * certificate. */
 115     int validation_failed;
 116
 117     LOG(DEBUG1, "new connection");
 118
 119     server_socket = -1;
 120     client_fd_read = NULL;
 121     client_fd_write = NULL;
 122     server_fd_read = NULL;
 123     server_fd_write = NULL;
 124     client_session_init = 0;
 125     server_session_init = 0;
 126     client_session_started = 0;
 127     server_session_started = 0;
 128     validation_failed = 0;
 129
 130     if (fdopen_read_write(client_socket, &client_fd_read,
 131                                          &client_fd_write) != 0) {
 132         goto out;
 133     }
 134
 135     /* Read request line (CONNECT ..) and headers (they are discarded). */
 136     result = read_http_request(client_fd_read, buffer, sizeof(buffer));
 137     if (result == -1) {
 138         LOG(WARNING, "read_http_request(): client read error");
 139         goto out;
 140     } else if (result == -2) {
 141         LOG(WARNING, "read_http_request(): client EOF");
 142         send_bad_request(client_fd_write);
 143         goto out;
 144     } else if (result == -3) {
 145         LOG(WARNING, "read_http_request(): proxy authentication failed");
 146         send_authentication_required(client_fd_write);
 147         goto out;
 148     }
 149
 150     if (parse_request(buffer, host, port, &version_minor) != 0) {
 151         LOG(WARNING, "bad request: >%s<", buffer);
 152         send_bad_request(client_fd_write);
 153         goto out;
 154     }
 155
 156     LOG(DEBUG2, "target: %s:%s (HTTP 1.%d)", host, port, version_minor);
 157
 158     /* Connect to proxy server or directly to server. */
 159     if (global_proxy_host != NULL && global_proxy_port != NULL) {
 160         LOG(DEBUG1, "connecting to %s:%s", global_proxy_host,
 161                                            global_proxy_port);
 162         server_socket = connect_to_host(global_proxy_host, global_proxy_port);
 163     } else {
 164         LOG(DEBUG1, "connecting to %s:%s", host, port);
 165         server_socket = connect_to_host(host, port);
 166     }
 167
 168     if (server_socket < 0) {
 169         LOG(WARNING, "failed to connect to server");
 170         send_forwarding_failure(client_fd_write);
 171         goto out;
 172     }
 173     if (fdopen_read_write(server_socket, &server_fd_read,
 174                                          &server_fd_write) != 0) {
 175         send_forwarding_failure(client_fd_write);
 176         goto out;
 177     }
 178
 179     /* Connect to proxy if requested (command line option). */
 180     if (global_proxy_host != NULL && global_proxy_port != NULL) {
 181         fprintf(server_fd_write, "CONNECT %s:%s HTTP/1.0\r\n", host, port);
 182         fprintf(server_fd_write, "\r\n");
 183         fflush(server_fd_write);
 184
 185         /* Read response line from proxy server. */
 186         result = read_http_request(server_fd_read, buffer, sizeof(buffer));
 187         if (result == -1) {
 188             LOG(WARNING, "read_http_request(): proxy read error");
 189             send_forwarding_failure(client_fd_write);
 190             goto out;
 191         } else if (result == -2) {
 192             LOG(WARNING, "read_http_request(): proxy EOF");
 193             send_forwarding_failure(client_fd_write);
 194             goto out;
 195         }
 196
 197         /* Check response of proxy server. */
 198         if (strncmp(buffer, "HTTP/1.0 200", 12)) {
 199             LOG(WARNING, "bad proxy response: >%s<", buffer);
 200             send_forwarding_failure(client_fd_write);
 201             goto out;
 202         }
 203     }
 204
 205     LOG(DEBUG1, "connection to server established");
 206
 207     /* If the -u option is used and we don't know this hostname's server
 208      * certificate then just pass through the connection and let the client
 209      * verify the server certificate. */
 210     if (global_passthrough_unknown) {
 211         char path[TLSPROXY_MAX_PATH_LENGTH];
 212         FILE *file = NULL;
 213
 214         if (server_certificate_file(&file, host, path, sizeof(path)) == -2) {
 215             /* We've established a connection, tell the client. */
 216             fprintf(client_fd_write, "HTTP/1.0 200 Connection established\r\n");
 217             fprintf(client_fd_write, "\r\n");
 218             fflush(client_fd_write);
 219
 220             LOG(DEBUG1, "transferring data");
 221
 222             /* Proxy data between client and server until one side is done
 223              * (EOF or error). */
 224             transfer_data(client_socket, server_socket);
 225
 226             LOG(DEBUG1, "finished transferring data");
 227
 228             goto out;
 229         }
 230         /* server_certificate_file() may have opened the file, close it. */
 231         if (file != NULL) {
 232             fclose(file);
 233         }
 234     }
 235
 236     /* Initialize TLS client credentials to talk to the server. */
 237     result = initialize_tls_session_server(server_socket, &server_session,
 238                                                           &server_x509_cred);
 239     if (result != 0) {
 240         LOG(WARNING, "initialize_tls_session_server() failed");
 241         send_forwarding_failure(client_fd_write);
 242         goto out;
 243     }
 244     server_session_init = 1;
 245
 246     LOG(DEBUG1, "starting server TLS handshake");
 247
 248     /* Try to establish TLS handshake between us and server. */
 249     result = gnutls_handshake(server_session);
 250     if (result != GNUTLS_E_SUCCESS) {
 251         LOG(WARNING, "server TLS handshake failed: %s",
 252                      gnutls_strerror(result));
 253         send_forwarding_failure(client_fd_write);
 254         goto out;
 255     }
 256     server_session_started = 1;
 257
 258     LOG(DEBUG1, "server TLS handshake finished");
 259
 260     if (global_log_level >= LOG_DEBUG2_LEVEL) {
 261         log_session_information(server_session);
 262     }
 263
 264     /* Make sure the server certificate is valid and known. */
 265     if (verify_tls_connection(server_session, host) != 0) {
 266         LOG(ERROR, "server certificate validation failed!");
 267         /* We'll send the error message over our TLS connection to the client,
 268          * but with an invalid certificate. No data is transfered from/to the
 269          * target server. */
 270         validation_failed = 1;
 271     }
 272
 273     /* Initialize TLS server credentials to talk to the client. */
 274     result = initialize_tls_session_client(client_socket,
 275                                            /* use a special host if the server
 276                                             * certificate was invalid */
 277                                            (validation_failed) ? "invalid"
 278                                                                : host,
 279                                            &client_session,
 280                                            &client_x509_cred);
 281     if (result != 0) {
 282         LOG(WARNING, "initialize_tls_session_client() failed");
 283         send_forwarding_failure(client_fd_write);
 284         goto out;
 285     }
 286     client_session_init = 1;
 287
 288     /* We've established a connection, tell the client. */
 289     fprintf(client_fd_write, "HTTP/1.0 200 Connection established\r\n");
 290     fprintf(client_fd_write, "\r\n");
 291     fflush(client_fd_write);
 292
 293     LOG(DEBUG1, "starting client TLS handshake");
 294
 295     /* Try to establish TLS handshake between client and us. */
 296     result = gnutls_handshake(client_session);
 297     if (result != GNUTLS_E_SUCCESS) {
 298         LOG(WARNING, "client TLS handshake failed: %s",
 299                      gnutls_strerror(result));
 300         send_forwarding_failure(client_fd_write);
 301         goto out;
 302     }
 303     client_session_started = 1;
 304
 305     LOG(DEBUG1, "client TLS handshake finished");
 306
 307     if (global_log_level >= LOG_DEBUG2_LEVEL) {
 308         log_session_information(client_session);
 309     }
 310
 311     /* Tell the client that the verification failed. Shouldn't be necessary as
 312      * the client should terminate the connection because he received the
 313      * invalid certificate but better be sure. */
 314     if (validation_failed) {
 315         tls_send_invalid_cert_message(client_session);
 316         goto out;
 317     }
 318
 319     LOG(DEBUG1, "transferring TLS data");
 320
 321     /* Proxy data between client and server until one side is done (EOF or
 322      * error). */
 323     transfer_data_tls(client_socket, server_socket,
 324                       client_session, server_session);
 325
 326     LOG(DEBUG1, "finished transferring TLS data");
 327
 328 out:
 329     /* Close TLS sessions if necessary. Use GNUTLS_SHUT_RDWR so the data is
 330      * reliable transmitted. */
 331     if (server_session_started) {
 332         /* Recent gnutls-serv (used in the test-suite) won't terminate the
 333          * connection when gnutls_bye(session, GNUTLS_SHUT_RDWR) is used
 334          * before any other data was received. If the validation failed just
 335          * close the connection without waiting for data, we won't read it
 336          * anyway.
 337          *
 338          * For verified connections GNUTLS_SHUT_RDWR is important or we might
 339          * lose data. */
 340         gnutls_bye(server_session, validation_failed ? GNUTLS_SHUT_WR
 341                                                      : GNUTLS_SHUT_RDWR);
 342     }
 343     if (client_session_started) {
 344         gnutls_bye(client_session, GNUTLS_SHUT_RDWR);
 345     }
 346     if (server_session_init) {
 347         gnutls_deinit(server_session);
 348         gnutls_certificate_free_credentials(server_x509_cred);
 349     }
 350     if (client_session_init) {
 351         gnutls_deinit(client_session);
 352         gnutls_certificate_free_credentials(client_x509_cred);
 353     }
 354
 355     /* Close connection to server/proxy. */
 356     if (server_fd_read != NULL) {
 357         if (server_fd_write != NULL) {
 358             fclose(server_fd_write);
 359         }
 360         fclose(server_fd_read);
 361     } else if (server_socket != -1) {
 362         close(server_socket);
 363     }
 364     LOG(DEBUG1, "connection to server closed");
 365     /* Close connection to client. */
 366     if (client_fd_read != NULL) {
 367         if (client_fd_write != NULL) {
 368             fclose(client_fd_write);
 369         }
 370         fclose(client_fd_read);
 371     } else {
 372         close(client_socket);
 373     }
 374     LOG(DEBUG1, "connection to client closed");
 375
 376     LOG(DEBUG1, "connection finished");
 377 }
 378
 379
 380 static int initialize_tls_session_client(int peer_socket,
 381         const char *hostname,
 382         gnutls_session_t *session,
 383         gnutls_certificate_credentials_t *x509_cred) {
 384     int result;
 385     int use_invalid_cert;
 386     char path[TLSPROXY_MAX_PATH_LENGTH];
 387
 388     /* The "invalid" hostname is special. If it's used we send an invalid
 389      * certificate to let the client know something is wrong. */
 390     use_invalid_cert = (!strcmp(hostname, "invalid"));
 391
 392     if (proxy_certificate_path(hostname, path, sizeof(path)) != 0) {
 393         LOG(ERROR,
 394             "initialize_tls_session_client(): "
 395             "failed to get proxy certificate path");
 396         return -1;
 397     }
 398
 399     result = gnutls_certificate_allocate_credentials(x509_cred);
 400     if (result != GNUTLS_E_SUCCESS) {
 401         LOG(ERROR,
 402             "initialize_tls_session_client(): "
 403             "gnutls_certificate_allocate_credentials(): %s",
 404             gnutls_strerror(result));
 405         return -1;
 406     }
 407
 408     /* Load proxy CA file, this CA "list" is send to the client. */
 409     if (!use_invalid_cert) {
 410         result = gnutls_certificate_set_x509_trust_file(*x509_cred,
 411                                                         PROXY_CA_PATH,
 412                                                         GNUTLS_X509_FMT_PEM);
 413         if (result <= 0) {
 414             LOG(ERROR,
 415                 "initialize_tls_session_client(): can't read CA file: '%s'",
 416                 PROXY_CA_PATH);
 417             gnutls_certificate_free_credentials(*x509_cred);
 418             return -1;
 419         } else if (result != 1) {
 420             /* Must contain only one CA, our proxy CA. */
 421             LOG(ERROR, "initialize_tls_session_client(): multiple CAs found");
 422             gnutls_certificate_free_credentials(*x509_cred);
 423             return -1;
 424         }
 425     }
 426     /* If the invalid hostname was specified do nothing, we use a self-signed
 427      * certificate in this case. */
 428
 429     /* And certificate for this website and proxy's private key. */
 430     if (!use_invalid_cert) {
 431         result = gnutls_certificate_set_x509_key_file(*x509_cred,
 432                                                       path,
 433                                                       PROXY_KEY_PATH,
 434                                                       GNUTLS_X509_FMT_PEM);
 435     /* If the invalid hostname was specified load our special "invalid"
 436      * certificate. */
 437     } else {
 438         result = gnutls_certificate_set_x509_key_file(*x509_cred,
 439                                                       PROXY_INVALID_CERT_PATH,
 440                                                       PROXY_KEY_PATH,
 441                                                       GNUTLS_X509_FMT_PEM);
 442     }
 443     if (result != GNUTLS_E_SUCCESS) {
 444         LOG(ERROR,
 445             "initialize_tls_session_client(): "
 446             "can't read server certificate ('%s') or key file ('%s'): %s",
 447             path, PROXY_KEY_PATH, gnutls_strerror(result));
 448         gnutls_certificate_free_credentials(*x509_cred);
 449         /* Could be a missing certificate. */
 450         return -2;
 451     }
 452
 453     gnutls_certificate_set_dh_params(*x509_cred, global_tls_dh_params);
 454
 455     return initialize_tls_session_both(GNUTLS_SERVER,
 456                                        peer_socket, session, x509_cred);
 457 }
 458 static int initialize_tls_session_server(int peer_socket,
 459         gnutls_session_t *session,
 460         gnutls_certificate_credentials_t *x509_cred) {
 461     int result;
 462
 463     result = gnutls_certificate_allocate_credentials(x509_cred);
 464     if (result != GNUTLS_E_SUCCESS) {
 465         LOG(ERROR,
 466             "initialize_tls_session_server(): "
 467             "gnutls_certificate_allocate_credentials(): %s",
 468             gnutls_strerror(result));
 469         return -1;
 470     }
 471
 472     return initialize_tls_session_both(GNUTLS_CLIENT,
 473                                        peer_socket, session, x509_cred);
 474 }
 475 static int initialize_tls_session_both(unsigned int flags,
 476         int peer_socket,
 477         gnutls_session_t *session,
 478         gnutls_certificate_credentials_t *x509_cred) {
 479     int result;
 480
 481     *session = NULL;
 482
 483     result = gnutls_init(session, flags);
 484     if (result != GNUTLS_E_SUCCESS) {
 485         LOG(ERROR,
 486             "initialize_tls_session_both(): gnutls_init(): %s",
 487             gnutls_strerror(result));
 488         goto err;
 489     }
 490     result = gnutls_priority_set(*session, global_tls_priority_cache);
 491     if (result != GNUTLS_E_SUCCESS) {
 492         LOG(ERROR,
 493             "initialize_tls_session_both(): gnutls_priority_set(): %s",
 494             gnutls_strerror(result));
 495         goto err;
 496     }
 497     result = gnutls_credentials_set(*session,
 498                                     GNUTLS_CRD_CERTIFICATE, *x509_cred);
 499     if (result != GNUTLS_E_SUCCESS) {
 500         LOG(ERROR,
 501             "initialize_tls_session_both(): gnutls_credentials_set(): %s",
 502             gnutls_strerror(result));
 503         goto err;
 504     }
 505
 506 #ifdef HAVE_GNUTLS_TRANSPORT_SET_INT2
 507     /* gnutls_transport_set_int() is a macro. */
 508     gnutls_transport_set_int(*session, peer_socket);
 509 #else
 510     gnutls_transport_set_ptr(*session, (gnutls_transport_ptr_t)peer_socket);
 511 #endif
 512
 513     return 0;
 514
 515 err:
 516     if (*session) {
 517         gnutls_deinit(*session);
 518     }
 519     gnutls_certificate_free_credentials(*x509_cred);
 520     return -1;
 521 }
 522
 523
 524 static int fdopen_read_write(int socket, FILE **read_fd, FILE **write_fd) {
 525     *read_fd = fdopen(socket, "r");
 526     if (*read_fd == NULL) {
 527         LOG_PERROR(WARNING, "fdopen_read_write(): fdopen(\"r\") failed");
 528         return -1;
 529     }
 530
 531     *write_fd = fdopen(dup(socket), "w");
 532     if (*write_fd == NULL) {
 533         LOG_PERROR(WARNING, "fdopen_read_write(): fdopen(\"w\") failed");
 534         fclose(*read_fd);
 535         *read_fd = NULL; /* "tell" caller read_fd is already closed */
 536         return -1;
 537     }
 538
 539     return 0;
 540 }
 541
 542 /* Read HTTP request line and headers (ignored).
 543  *
 544  * On success 0 is returned, -1 on client error, -2 on unexpected EOF.
 545  */
 546 static int read_http_request(FILE *client_fd, char *request, size_t length) {
 547     char buffer[MAX_REQUEST_LINE];
 548     int found_proxy_authorization;
 549
 550     assert(length <= INT_MAX);
 551     if (fgets(request, (int)length, client_fd) == NULL) {
 552         if (ferror(client_fd)) {
 553             LOG_PERROR(WARNING, "read_http_request(): fgets()");
 554             return -1;
 555         }
 556         /* EOF */
 557         return -2;
 558     }
 559
 560     found_proxy_authorization = 0;
 561     while (fgets(buffer, sizeof(buffer), client_fd) != NULL) {
 562         const char *authentication = "Proxy-Authorization: Basic ";
 563
 564         if (global_http_digest_authorization != NULL
 565                 && !strncmp(buffer, authentication, strlen(authentication))) {
 566             found_proxy_authorization = 1;
 567
 568             /* Check if the passphrase matches. */
 569             strtok(buffer, "\r\n");
 570             if (strcmp(buffer + strlen(authentication),
 571                        global_http_digest_authorization)) {
 572                 return -3;
 573             }
 574         }
 575
 576         /* End of header. */
 577         if (!strcmp(buffer, "\n") || !strcmp(buffer, "\r\n")) {
 578             break;
 579         }
 580     }
 581     if (ferror(client_fd)) {
 582         LOG_PERROR(WARNING, "read_http_request(): fgets()");
 583         return -1;
 584     } else if (feof(client_fd)) {
 585         return -2;
 586     }
 587
 588     if (global_http_digest_authorization != NULL && !found_proxy_authorization) {
 589         return -3;
 590     }
 591
 592     return 0;
 593 }
 594
 595 static void send_bad_request(FILE *client_fd) {
 596     const char error[] = "400 Bad Request";
 597     const char msg[]   = "Your browser sent an invalid request.";
 598     fprintf(client_fd, HTTP_RESPONSE_FORMAT, error, "", error, error, msg);
 599     fflush(client_fd);
 600 }
 601 static void send_authentication_required(FILE *client_fd) {
 602     const char error[] = "407 Proxy Authentication Required";
 603     const char auth[]  = "Proxy-Authenticate: Basic realm=\"tlsproxy\"\r\n";
 604     const char msg[]   = "TODO";
 605     fprintf(client_fd, HTTP_RESPONSE_FORMAT, error, auth, error, error, msg);
 606     fflush(client_fd);
 607 }
 608 static void send_forwarding_failure(FILE *client_fd) {
 609     const char error[] = "503 Forwarding failure";
 610     const char msg[]   = "Failed to connect to server, check logs.";
 611     fprintf(client_fd, HTTP_RESPONSE_FORMAT, error, "", error, error, msg);
 612     fflush(client_fd);
 613 }
 614 static void tls_send_invalid_cert_message(gnutls_session_t session) {
 615     const char error[] = "500 Internal Server Error";
 616     const char msg[]   = "Server certificate validation failed, check logs.";
 617
 618     int result;
 619     char buffer[sizeof(HTTP_RESPONSE_FORMAT)
 620                 + 3 * sizeof(error) + sizeof(msg)];
 621
 622     result = snprintf(buffer, sizeof(buffer), HTTP_RESPONSE_FORMAT,
 623                                               error, "", error, error, msg);
 624     assert(result > 0 && (size_t)result < sizeof(buffer));
 625
 626     gnutls_record_send(session, buffer, strlen(buffer));
 627 }
 628
 629
 630 /* Transfer data between client and server sockets until one closes the
 631  * connection. */
 632 static void transfer_data(int client, int server) {
 633     struct pollfd fds[2];
 634     fds[0].fd      = client;
 635     fds[0].events  = POLLIN | POLLPRI | POLLHUP | POLLERR;
 636     fds[0].revents = 0;
 637     fds[1].fd      = server;
 638     fds[1].events  = POLLIN | POLLPRI | POLLHUP | POLLERR;
 639     fds[1].revents = 0;
 640
 641     LOG(DEBUG2, "transfer_data(): %d -> %d", client, server);
 642
 643     for (;;) {
 644         int result = poll(fds, 2 /* fd count */, -1 /* no timeout */);
 645         if (result < 0) {
 646             LOG_PERROR(ERROR, "transfer_data(): poll()");
 647             return;
 648         }
 649
 650         /* Data available from client. */
 651         if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
 652             if (read_from_write_to(client, server) != 0) {
 653                 /* EOF (or other error) */
 654                 break;
 655             }
 656         }
 657         /* Data available from server. */
 658         if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
 659             if (read_from_write_to(server, client) != 0) {
 660                 /* EOF (or other error) */
 661                 break;
 662             }
 663         }
 664
 665         /* Client closed connection. */
 666         if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
 667             break;
 668         }
 669         /* Server closed connection. */
 670         if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
 671             break;
 672         }
 673     }
 674 }
 675
 676 /* Read available data from socket from and write it to socket to. At maximum
 677  * 4096 bytes are read/written. */
 678 static int read_from_write_to(int from, int to) {
 679     ssize_t size_read;
 680     ssize_t size_written;
 681     char buffer[4096];
 682
 683     size_read = read(from, buffer, sizeof(buffer));
 684     if (size_read < 0) {
 685         LOG_PERROR(WARNING, "read_from_write_to(): read()");
 686         return -1;
 687     /* EOF */
 688     } else if (size_read == 0) {
 689         return -1;
 690     }
 691
 692     size_written = write(to, buffer, (size_t)size_read);
 693     if (size_written < 0) {
 694         LOG_PERROR(WARNING, "read_from_write_to(): write()");
 695         return -1;
 696     }
 697     if (size_read != size_written) {
 698         LOG(ERROR, "read_from_write_to(): only written %ld of %ld bytes!",
 699                    (long int)size_written, (long int)size_read);
 700         return -1;
 701     }
 702
 703     return 0;
 704 }
 705
 706 /* Transfer data between client and server TLS connection until one closes the
 707  * connection. */
 708 static void transfer_data_tls(int client, int server,
 709                               gnutls_session_t client_session,
 710                               gnutls_session_t server_session) {
 711     size_t buffer_size;
 712
 713     struct pollfd fds[2];
 714     fds[0].fd      = client;
 715     fds[0].events  = POLLIN | POLLPRI | POLLHUP | POLLERR;
 716     fds[0].revents = 0;
 717     fds[1].fd      = server;
 718     fds[1].events  = POLLIN | POLLPRI | POLLHUP | POLLERR;
 719     fds[1].revents = 0;
 720
 721     /* Get maximum possible buffer size. */
 722     buffer_size = gnutls_record_get_max_size(client_session);
 723     if (gnutls_record_get_max_size(server_session) < buffer_size) {
 724         buffer_size = gnutls_record_get_max_size(server_session);
 725     }
 726     LOG(DEBUG2, "transfer_data_tls(): suggested buffer size: %ld",
 727                 (long int)buffer_size);
 728
 729     for (;;) {
 730         int result = poll(fds, 2 /* fd count */, -1 /* no timeout */);
 731         if (result < 0) {
 732             LOG_PERROR(ERROR, "transfer_data(): poll()");
 733             return;
 734         }
 735
 736         /* Data available from client. */
 737         if (fds[0].revents & POLLIN || fds[0].revents & POLLPRI) {
 738             if (read_from_write_to_tls(client_session, server_session,
 739                                        buffer_size) != 0) {
 740                 /* EOF (or other error) */
 741                 break;
 742             }
 743         }
 744         /* Data available from server. */
 745         if (fds[1].revents & POLLIN || fds[1].revents & POLLPRI) {
 746             if (read_from_write_to_tls(server_session, client_session,
 747                                        buffer_size) != 0) {
 748                 /* EOF (or other error) */
 749                 break;
 750             }
 751         }
 752
 753         /* Client closed connection. */
 754         if (fds[0].revents & POLLERR || fds[0].revents & POLLHUP) {
 755             break;
 756         }
 757         /* Server closed connection. */
 758         if (fds[1].revents & POLLERR || fds[1].revents & POLLHUP) {
 759             break;
 760         }
 761     }
 762 }
 763
 764 /* Read available data from session from and write to session to. */
 765 static int read_from_write_to_tls(gnutls_session_t from,
 766                                   gnutls_session_t to,
 767                                   size_t buffer_size) {
 768     ssize_t size_read;
 769     ssize_t size_written;
 770     char buffer[16384];
 771
 772     if (buffer_size > sizeof(buffer)) {
 773         LOG(WARNING, "read_from_write_to_tls(): reduced buffer size to %ld",
 774                      (long int)(sizeof(buffer)));
 775         buffer_size = sizeof(buffer);
 776     }
 777
 778     size_read = gnutls_record_recv(from, buffer, buffer_size);
 779     if (size_read < 0) {
 780         LOG(WARNING, "read_from_write_to_tls(): gnutls_record_recv(): %s",
 781                      gnutls_strerror((int)size_read));
 782         return -1;
 783     /* EOF */
 784     } else if (size_read == 0) {
 785         return -1;
 786     }
 787
 788     size_written = gnutls_record_send(to, buffer, (size_t)size_read);
 789     if (size_written < 0) {
 790         LOG(WARNING, "read_from_write_to_tls(): gnutls_record_send(): %s",
 791                      gnutls_strerror((int)size_written));
 792         return -1;
 793     }
 794     if (size_read != size_written) {
 795         LOG(ERROR, "read_from_write_to_tls(): only written %ld of %ld bytes!",
 796                    (long int)size_written, (long int)size_read);
 797         return -1;
 798     }
 799
 800     return 0;
 801 }
 802
 803
 804 static int connect_to_host(const char *hostname, const char *port) {
 805     struct addrinfo gai_hints;
 806     struct addrinfo *gai_result;
 807     int gai_return;
 808
 809     int server_socket;
 810     struct addrinfo *server;
 811
 812     if (hostname == NULL || port == NULL) {
 813         return -1;
 814     }
 815
 816     /* Get IP of hostname server. */
 817     memset(&gai_hints, 0, sizeof(gai_hints));
 818     gai_hints.ai_family   = AF_UNSPEC;
 819     gai_hints.ai_socktype = SOCK_STREAM;
 820     gai_hints.ai_protocol = 0;
 821     gai_hints.ai_flags    = AI_NUMERICSERV /* given port is numeric */
 822                           | AI_ADDRCONFIG  /* supported by this computer */
 823                           | AI_V4MAPPED;   /* support IPv4 through IPv6 */
 824     gai_return = getaddrinfo(hostname, port, &gai_hints, &gai_result);
 825     if (gai_return != 0) {
 826         if (gai_return == EAI_SYSTEM) {
 827             LOG_PERROR(WARNING, "connect_to_host(): getaddrinfo()");
 828         } else {
 829             LOG(WARNING, "connect_to_host(): getaddrinfo(): %s",
 830                          gai_strerror(gai_return));
 831         }
 832         return -1;
 833     }
 834
 835     /* Now try to connect to each server returned by getaddrinfo(), use the
 836      * first successful connect. */
 837     for (server = gai_result; server != NULL; server = server->ai_next) {
 838         server_socket = socket(server->ai_family,
 839                                server->ai_socktype,
 840                                server->ai_protocol);
 841         if (server_socket < 0) {
 842             LOG_PERROR(DEBUG1, "connect_to_host(): socket(), trying next");
 843             continue;
 844         }
 845
 846         if (connect(server_socket, server->ai_addr, server->ai_addrlen) == 0) {
 847             break;
 848         }
 849         LOG_PERROR(DEBUG1, "connect_to_host(): connect(), trying next");
 850
 851         close(server_socket);
 852     }
 853     /* Make sure we free the result from getaddrinfo(). */
 854     freeaddrinfo(gai_result);
 855
 856     if (server == NULL) {
 857         LOG_PERROR(WARNING, "connect_to_host(): no server found, abort");
 858         return -1;
 859     }
 860
 861     return server_socket;
 862 }
 863
 864
 865 /* Parse HTTP CONNECT request string and save its parameters.
 866  *
 867  * The following format is expected: "CONNECT host:port HTTP/1.x".
 868  *
 869  * request and host must have the same size! port must be at least 6 bytes
 870  * long (5 + '\0').
 871  */
 872 static int parse_request(const char *request, char *host, char *port,
 873                                               int *version_minor) {
 874     int port_unused; /* just used to verify the port is numeric */
 875     char *position;
 876
 877     /* scanf() doesn't check spaces. */
 878     if (strncmp(request, "CONNECT ", 8)) {
 879         return -1;
 880     }
 881     /* Check request and extract data, "host:port" is not yet separated. */
 882     if (sscanf(request, "CONNECT %s HTTP/1.%d", host, version_minor) != 2) {
 883         return -1;
 884     }
 885     /* Make sure ":port" is there. */
 886     if ((position = strchr(host, ':')) == NULL) {
 887         return -1;
 888     }
 889     /* Make sure port is numeric. */
 890     if (sscanf(position + 1, "%d", &port_unused) != 1) {
 891         return -1;
 892     }
 893     /* Store it in *port. */
 894     strncpy(port, position + 1, 5);
 895     port[5] = '\0';
 896     /* And remove port from host. */
 897     *position = '\0';
 898
 899     return 0;
 900 }
 901
 902
 903 static void log_session_information(gnutls_session_t session) {
 904     /* From doc/examples/ex-session-info.c of GnuTLS 3.2.3's tarball and
 905      * modified, thanks. */
 906
 907     const char *tmp;
 908     gnutls_credentials_type_t cred;
 909     gnutls_kx_algorithm_t kx;
 910     int dhe, ecdh;
 911
 912     dhe = 0;
 913     ecdh = 0;
 914
 915     /* Key exchange algorithm. */
 916     kx = gnutls_kx_get(session);
 917     LOG(DEBUG2, "- key exchange: %s", gnutls_kx_get_name(kx));
 918
 919     /* Authentication type. */
 920     cred = gnutls_auth_get_type(session);
 921     switch (cred) {
 922         case GNUTLS_CRD_CERTIFICATE:
 923             if (kx == GNUTLS_KX_DHE_RSA
 924                     || kx == GNUTLS_KX_DHE_DSS) {
 925                 dhe = 1;
 926 #ifdef GNUTLS_KX_ECDHE_RSA
 927             } else if (kx == GNUTLS_KX_ECDHE_RSA
 928                     || kx == GNUTLS_KX_ECDHE_ECDSA) {
 929                 ecdh = 1;
 930 #endif
 931             }
 932             break;
 933
 934         case GNUTLS_CRD_IA:
 935         case GNUTLS_CRD_SRP:
 936         case GNUTLS_CRD_PSK:
 937         case GNUTLS_CRD_ANON:
 938         default:
 939             /* This shouldn't occur. */
 940             LOG(WARNING, "unexpected authentication method: %d", cred);
 941             break;
 942     }
 943
 944     /* Information about key exchange. */
 945     if (dhe) {
 946         LOG(DEBUG2, "- ephemeral DH using prime of %d bits",
 947                     gnutls_dh_get_prime_bits(session));
 948     } else if (ecdh) {
 949 #ifdef GNUTLS_KX_ECDHE_RSA
 950         LOG(DEBUG2, "- ephemeral ECDH using curve %s",
 951                     gnutls_ecc_curve_get_name(gnutls_ecc_curve_get(session)));
 952 #endif
 953     }
 954
 955     tmp = gnutls_protocol_get_name(gnutls_protocol_get_version(session));
 956     LOG(DEBUG2, "- protocol: %s", tmp); /* e.g. TLS 1.0 */
 957
 958     tmp = gnutls_certificate_type_get_name(gnutls_certificate_type_get(session));
 959     LOG(DEBUG2, "- certificate type: %s", tmp);
 960
 961     tmp = gnutls_compression_get_name(gnutls_compression_get(session));
 962     LOG(DEBUG2, "- compression: %s", tmp);
 963
 964     tmp = gnutls_cipher_get_name(gnutls_cipher_get(session));
 965     LOG(DEBUG2, "- cipher: %s", tmp);
 966
 967     tmp = gnutls_mac_get_name(gnutls_mac_get(session));
 968     LOG(DEBUG2, "- MAC: %s", tmp);
 969 }