crypto/dist/heimdal/kdc/connect.c

   1 /*
   2  * Copyright (c) 1997-2005 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "kdc_locl.h"
  35
  36 __RCSID("$Heimdal: connect.c 22434 2008-01-14 09:21:37Z lha $"
  37         "$NetBSD$");
  38
  39 /* Should we enable the HTTP hack? */
  40 int enable_http = -1;
  41
  42 /* Log over requests to the KDC */
  43 const char *request_log;
  44
  45 /* A string describing on what ports to listen */
  46 const char *port_str;
  47
  48 krb5_addresses explicit_addresses;
  49
  50 size_t max_request;             /* maximal size of a request */
  51
  52 /*
  53  * a tuple describing on what to listen
  54  */
  55
  56 struct port_desc{
  57     int family;
  58     int type;
  59     int port;
  60 };
  61
  62 /* the current ones */
  63
  64 static struct port_desc *ports;
  65 static int num_ports;
  66
  67 /*
  68  * add `family, port, protocol' to the list with duplicate suppresion.
  69  */
  70
  71 static void
  72 add_port(krb5_context context,
  73          int family, int port, const char *protocol)
  74 {
  75     int type;
  76     int i;
  77
  78     if(strcmp(protocol, "udp") == 0)
  79         type = SOCK_DGRAM;
  80     else if(strcmp(protocol, "tcp") == 0)
  81         type = SOCK_STREAM;
  82     else
  83         return;
  84     for(i = 0; i < num_ports; i++){
  85         if(ports[i].type == type
  86            && ports[i].port == port
  87            && ports[i].family == family)
  88             return;
  89     }
  90     ports = realloc(ports, (num_ports + 1) * sizeof(*ports));
  91     if (ports == NULL)
  92         krb5_err (context, 1, errno, "realloc");
  93     ports[num_ports].family = family;
  94     ports[num_ports].type   = type;
  95     ports[num_ports].port   = port;
  96     num_ports++;
  97 }
  98
  99 /*
 100  * add a triple but with service -> port lookup
 101  * (this prints warnings for stuff that does not exist)
 102  */
 103
 104 static void
 105 add_port_service(krb5_context context,
 106                  int family, const char *service, int port,
 107                  const char *protocol)
 108 {
 109     port = krb5_getportbyname (context, service, protocol, port);
 110     add_port (context, family, port, protocol);
 111 }
 112
 113 /*
 114  * add the port with service -> port lookup or string -> number
 115  * (no warning is printed)
 116  */
 117
 118 static void
 119 add_port_string (krb5_context context,
 120                  int family, const char *str, const char *protocol)
 121 {
 122     struct servent *sp;
 123     int port;
 124
 125     sp = roken_getservbyname (str, protocol);
 126     if (sp != NULL) {
 127         port = sp->s_port;
 128     } else {
 129         char *end;
 130
 131         port = htons(strtol(str, &end, 0));
 132         if (end == str)
 133             return;
 134     }
 135     add_port (context, family, port, protocol);
 136 }
 137
 138 /*
 139  * add the standard collection of ports for `family'
 140  */
 141
 142 static void
 143 add_standard_ports (krb5_context context,
 144                     krb5_kdc_configuration *config,
 145                     int family)
 146 {
 147     add_port_service(context, family, "kerberos", 88, "udp");
 148     add_port_service(context, family, "kerberos", 88, "tcp");
 149     add_port_service(context, family, "kerberos-sec", 88, "udp");
 150     add_port_service(context, family, "kerberos-sec", 88, "tcp");
 151     if(enable_http)
 152         add_port_service(context, family, "http", 80, "tcp");
 153     if(config->enable_524) {
 154         add_port_service(context, family, "krb524", 4444, "udp");
 155         add_port_service(context, family, "krb524", 4444, "tcp");
 156     }
 157     if(config->enable_v4) {
 158         add_port_service(context, family, "kerberos-iv", 750, "udp");
 159         add_port_service(context, family, "kerberos-iv", 750, "tcp");
 160     }
 161     if (config->enable_kaserver)
 162         add_port_service(context, family, "afs3-kaserver", 7004, "udp");
 163     if(config->enable_kx509) {
 164         add_port_service(context, family, "kca_service", 9878, "udp");
 165         add_port_service(context, family, "kca_service", 9878, "tcp");
 166     }
 167
 168 }
 169
 170 /*
 171  * parse the set of space-delimited ports in `str' and add them.
 172  * "+" => all the standard ones
 173  * otherwise it's port|service[/protocol]
 174  */
 175
 176 static void
 177 parse_ports(krb5_context context,
 178             krb5_kdc_configuration *config,
 179             const char *str)
 180 {
 181     char *pos = NULL;
 182     char *p;
 183     char *str_copy = strdup (str);
 184
 185     p = strtok_r(str_copy, " \t", &pos);
 186     while(p != NULL) {
 187         if(strcmp(p, "+") == 0) {
 188 #ifdef HAVE_IPV6
 189             add_standard_ports(context, config, AF_INET6);
 190 #endif
 191             add_standard_ports(context, config, AF_INET);
 192         } else {
 193             char *q = strchr(p, '/');
 194             if(q){
 195                 *q++ = 0;
 196 #ifdef HAVE_IPV6
 197                 add_port_string(context, AF_INET6, p, q);
 198 #endif
 199                 add_port_string(context, AF_INET, p, q);
 200             }else {
 201 #ifdef HAVE_IPV6
 202                 add_port_string(context, AF_INET6, p, "udp");
 203                 add_port_string(context, AF_INET6, p, "tcp");
 204 #endif
 205                 add_port_string(context, AF_INET, p, "udp");
 206                 add_port_string(context, AF_INET, p, "tcp");
 207             }
 208         }
 209
 210         p = strtok_r(NULL, " \t", &pos);
 211     }
 212     free (str_copy);
 213 }
 214
 215 /*
 216  * every socket we listen on
 217  */
 218
 219 struct descr {
 220     int s;
 221     int type;
 222     int port;
 223     unsigned char *buf;
 224     size_t size;
 225     size_t len;
 226     time_t timeout;
 227     struct sockaddr_storage __ss;
 228     struct sockaddr *sa;
 229     socklen_t sock_len;
 230     char addr_string[128];
 231 };
 232
 233 static void
 234 init_descr(struct descr *d)
 235 {
 236     memset(d, 0, sizeof(*d));
 237     d->sa = (struct sockaddr *)&d->__ss;
 238     d->s = -1;
 239 }
 240
 241 /*
 242  * re-initialize all `n' ->sa in `d'.
 243  */
 244
 245 static void
 246 reinit_descrs (struct descr *d, int n)
 247 {
 248     int i;
 249
 250     for (i = 0; i < n; ++i)
 251         d[i].sa = (struct sockaddr *)&d[i].__ss;
 252 }
 253
 254 /*
 255  * Create the socket (family, type, port) in `d'
 256  */
 257
 258 static void
 259 init_socket(krb5_context context,
 260             krb5_kdc_configuration *config,
 261             struct descr *d, krb5_address *a, int family, int type, int port)
 262 {
 263     krb5_error_code ret;
 264     struct sockaddr_storage __ss;
 265     struct sockaddr *sa = (struct sockaddr *)&__ss;
 266     krb5_socklen_t sa_size = sizeof(__ss);
 267
 268     init_descr (d);
 269
 270     ret = krb5_addr2sockaddr (context, a, sa, &sa_size, port);
 271     if (ret) {
 272         krb5_warn(context, ret, "krb5_addr2sockaddr");
 273         close(d->s);
 274         d->s = -1;
 275         return;
 276     }
 277
 278     if (sa->sa_family != family)
 279         return;
 280
 281     d->s = socket(family, type, 0);
 282     if(d->s < 0){
 283         krb5_warn(context, errno, "socket(%d, %d, 0)", family, type);
 284         d->s = -1;
 285         return;
 286     }
 287 #if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_REUSEADDR)
 288     {
 289         int one = 1;
 290         setsockopt(d->s, SOL_SOCKET, SO_REUSEADDR, (void *)&one, sizeof(one));
 291     }
 292 #endif
 293     d->type = type;
 294     d->port = port;
 295
 296     if(bind(d->s, sa, sa_size) < 0){
 297         char a_str[256];
 298         size_t len;
 299
 300         krb5_print_address (a, a_str, sizeof(a_str), &len);
 301         krb5_warn(context, errno, "bind %s/%d", a_str, ntohs(port));
 302         close(d->s);
 303         d->s = -1;
 304         return;
 305     }
 306     if(type == SOCK_STREAM && listen(d->s, SOMAXCONN) < 0){
 307         char a_str[256];
 308         size_t len;
 309
 310         krb5_print_address (a, a_str, sizeof(a_str), &len);
 311         krb5_warn(context, errno, "listen %s/%d", a_str, ntohs(port));
 312         close(d->s);
 313         d->s = -1;
 314         return;
 315     }
 316 }
 317
 318 /*
 319  * Allocate descriptors for all the sockets that we should listen on
 320  * and return the number of them.
 321  */
 322
 323 static int
 324 init_sockets(krb5_context context,
 325              krb5_kdc_configuration *config,
 326              struct descr **desc)
 327 {
 328     krb5_error_code ret;
 329     int i, j;
 330     struct descr *d;
 331     int num = 0;
 332     krb5_addresses addresses;
 333
 334     if (explicit_addresses.len) {
 335         addresses = explicit_addresses;
 336     } else {
 337         ret = krb5_get_all_server_addrs (context, &addresses);
 338         if (ret)
 339             krb5_err (context, 1, ret, "krb5_get_all_server_addrs");
 340     }
 341     parse_ports(context, config, port_str);
 342     d = malloc(addresses.len * num_ports * sizeof(*d));
 343     if (d == NULL)
 344         krb5_errx(context, 1, "malloc(%lu) failed",
 345                   (unsigned long)num_ports * sizeof(*d));
 346
 347     for (i = 0; i < num_ports; i++){
 348         for (j = 0; j < addresses.len; ++j) {
 349             init_socket(context, config, &d[num], &addresses.val[j],
 350                         ports[i].family, ports[i].type, ports[i].port);
 351             if(d[num].s != -1){
 352                 char a_str[80];
 353                 size_t len;
 354
 355                 krb5_print_address (&addresses.val[j], a_str,
 356                                     sizeof(a_str), &len);
 357
 358                 kdc_log(context, config, 5, "listening on %s port %u/%s",
 359                         a_str,
 360                         ntohs(ports[i].port),
 361                         (ports[i].type == SOCK_STREAM) ? "tcp" : "udp");
 362                 /* XXX */
 363                 num++;
 364             }
 365         }
 366     }
 367     krb5_free_addresses (context, &addresses);
 368     d = realloc(d, num * sizeof(*d));
 369     if (d == NULL && num != 0)
 370         krb5_errx(context, 1, "realloc(%lu) failed",
 371                   (unsigned long)num * sizeof(*d));
 372     reinit_descrs (d, num);
 373     *desc = d;
 374     return num;
 375 }
 376
 377 /*
 378  *
 379  */
 380
 381 static const char *
 382 descr_type(struct descr *d)
 383 {
 384     if (d->type == SOCK_DGRAM)
 385         return "udp";
 386     else if (d->type == SOCK_STREAM)
 387         return "tcp";
 388     return "unknown";
 389 }
 390
 391 static void
 392 addr_to_string(krb5_context context,
 393                struct sockaddr *addr, size_t addr_len, char *str, size_t len)
 394 {
 395     krb5_address a;
 396     if(krb5_sockaddr2address(context, addr, &a) == 0) {
 397         if(krb5_print_address(&a, str, len, &len) == 0) {
 398             krb5_free_address(context, &a);
 399             return;
 400         }
 401         krb5_free_address(context, &a);
 402     }
 403     snprintf(str, len, "<family=%d>", addr->sa_family);
 404 }
 405
 406 /*
 407  *
 408  */
 409
 410 static void
 411 send_reply(krb5_context context,
 412            krb5_kdc_configuration *config,
 413            krb5_boolean prependlength,
 414            struct descr *d,
 415            krb5_data *reply)
 416 {
 417     kdc_log(context, config, 5,
 418             "sending %lu bytes to %s", (unsigned long)reply->length,
 419             d->addr_string);
 420     if(prependlength){
 421         unsigned char l[4];
 422         l[0] = (reply->length >> 24) & 0xff;
 423         l[1] = (reply->length >> 16) & 0xff;
 424         l[2] = (reply->length >> 8) & 0xff;
 425         l[3] = reply->length & 0xff;
 426         if(sendto(d->s, l, sizeof(l), 0, d->sa, d->sock_len) < 0) {
 427             kdc_log (context, config,
 428                      0, "sendto(%s): %s", d->addr_string, strerror(errno));
 429             return;
 430         }
 431     }
 432     if(sendto(d->s, reply->data, reply->length, 0, d->sa, d->sock_len) < 0) {
 433         kdc_log (context, config,
 434                  0, "sendto(%s): %s", d->addr_string, strerror(errno));
 435         return;
 436     }
 437 }
 438
 439 /*
 440  * Handle the request in `buf, len' to socket `d'
 441  */
 442
 443 static void
 444 do_request(krb5_context context,
 445            krb5_kdc_configuration *config,
 446            void *buf, size_t len, krb5_boolean prependlength,
 447            struct descr *d)
 448 {
 449     krb5_error_code ret;
 450     krb5_data reply;
 451     int datagram_reply = (d->type == SOCK_DGRAM);
 452
 453     krb5_kdc_update_time(NULL);
 454
 455     krb5_data_zero(&reply);
 456     ret = krb5_kdc_process_request(context, config,
 457                                    buf, len, &reply, &prependlength,
 458                                    d->addr_string, d->sa,
 459                                    datagram_reply);
 460     if(request_log)
 461         krb5_kdc_save_request(context, request_log, buf, len, &reply, d->sa);
 462     if(reply.length){
 463         send_reply(context, config, prependlength, d, &reply);
 464         krb5_data_free(&reply);
 465     }
 466     if(ret)
 467         kdc_log(context, config, 0,
 468                 "Failed processing %lu byte request from %s",
 469                 (unsigned long)len, d->addr_string);
 470 }
 471
 472 /*
 473  * Handle incoming data to the UDP socket in `d'
 474  */
 475
 476 static void
 477 handle_udp(krb5_context context,
 478            krb5_kdc_configuration *config,
 479            struct descr *d)
 480 {
 481     unsigned char *buf;
 482     int n;
 483
 484     buf = malloc(max_request);
 485     if(buf == NULL){
 486         kdc_log(context, config, 0, "Failed to allocate %lu bytes", (unsigned long)max_request);
 487         return;
 488     }
 489
 490     d->sock_len = sizeof(d->__ss);
 491     n = recvfrom(d->s, buf, max_request, 0, d->sa, &d->sock_len);
 492     if(n < 0)
 493         krb5_warn(context, errno, "recvfrom");
 494     else {
 495         addr_to_string (context, d->sa, d->sock_len,
 496                         d->addr_string, sizeof(d->addr_string));
 497         do_request(context, config, buf, n, FALSE, d);
 498     }
 499     free (buf);
 500 }
 501
 502 static void
 503 clear_descr(struct descr *d)
 504 {
 505     if(d->buf)
 506         memset(d->buf, 0, d->size);
 507     d->len = 0;
 508     if(d->s != -1)
 509         close(d->s);
 510     d->s = -1;
 511 }
 512
 513
 514 /* remove HTTP %-quoting from buf */
 515 static int
 516 de_http(char *buf)
 517 {
 518     unsigned char *p, *q;
 519     for(p = q = (unsigned char *)buf; *p; p++, q++) {
 520         if(*p == '%' && isxdigit(p[1]) && isxdigit(p[2])) {
 521             unsigned int x;
 522             if(sscanf((char *)p + 1, "%2x", &x) != 1)
 523                 return -1;
 524             *q = x;
 525             p += 2;
 526         } else
 527             *q = *p;
 528     }
 529     *q = '\0';
 530     return 0;
 531 }
 532
 533 #define TCP_TIMEOUT 4
 534
 535 /*
 536  * accept a new TCP connection on `d[parent]' and store it in `d[child]'
 537  */
 538
 539 static void
 540 add_new_tcp (krb5_context context,
 541              krb5_kdc_configuration *config,
 542              struct descr *d, int parent, int child)
 543 {
 544     int s;
 545
 546     if (child == -1)
 547         return;
 548
 549     d[child].sock_len = sizeof(d[child].__ss);
 550     s = accept(d[parent].s, d[child].sa, &d[child].sock_len);
 551     if(s < 0) {
 552         krb5_warn(context, errno, "accept");
 553         return;
 554     }
 555
 556     if (s >= FD_SETSIZE) {
 557         krb5_warnx(context, "socket FD too large");
 558         close (s);
 559         return;
 560     }
 561
 562     d[child].s = s;
 563     d[child].timeout = time(NULL) + TCP_TIMEOUT;
 564     d[child].type = SOCK_STREAM;
 565     addr_to_string (context,
 566                     d[child].sa, d[child].sock_len,
 567                     d[child].addr_string, sizeof(d[child].addr_string));
 568 }
 569
 570 /*
 571  * Grow `d' to handle at least `n'.
 572  * Return != 0 if fails
 573  */
 574
 575 static int
 576 grow_descr (krb5_context context,
 577             krb5_kdc_configuration *config,
 578             struct descr *d, size_t n)
 579 {
 580     if (d->size - d->len < n) {
 581         unsigned char *tmp;
 582         size_t grow;
 583
 584         grow = max(1024, d->len + n);
 585         if (d->size + grow > max_request) {
 586             kdc_log(context, config, 0, "Request exceeds max request size (%lu bytes).",
 587                     (unsigned long)d->size + grow);
 588             clear_descr(d);
 589             return -1;
 590         }
 591         tmp = realloc (d->buf, d->size + grow);
 592         if (tmp == NULL) {
 593             kdc_log(context, config, 0, "Failed to re-allocate %lu bytes.",
 594                     (unsigned long)d->size + grow);
 595             clear_descr(d);
 596             return -1;
 597         }
 598         d->size += grow;
 599         d->buf = tmp;
 600     }
 601     return 0;
 602 }
 603
 604 /*
 605  * Try to handle the TCP data at `d->buf, d->len'.
 606  * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 607  */
 608
 609 static int
 610 handle_vanilla_tcp (krb5_context context,
 611                     krb5_kdc_configuration *config,
 612                     struct descr *d)
 613 {
 614     krb5_storage *sp;
 615     uint32_t len;
 616
 617     sp = krb5_storage_from_mem(d->buf, d->len);
 618     if (sp == NULL) {
 619         kdc_log (context, config, 0, "krb5_storage_from_mem failed");
 620         return -1;
 621     }
 622     krb5_ret_uint32(sp, &len);
 623     krb5_storage_free(sp);
 624     if(d->len - 4 >= len) {
 625         memmove(d->buf, d->buf + 4, d->len - 4);
 626         d->len -= 4;
 627         return 1;
 628     }
 629     return 0;
 630 }
 631
 632 /*
 633  * Try to handle the TCP/HTTP data at `d->buf, d->len'.
 634  * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 635  */
 636
 637 static int
 638 handle_http_tcp (krb5_context context,
 639                  krb5_kdc_configuration *config,
 640                  struct descr *d)
 641 {
 642     char *s, *p, *t;
 643     void *data;
 644     char *proto;
 645     int len;
 646
 647     s = (char *)d->buf;
 648
 649     p = strstr(s, "\r\n");
 650     if (p == NULL) {
 651         kdc_log(context, config, 0, "Malformed HTTP request from %s", d->addr_string);
 652         return -1;
 653     }
 654     *p = 0;
 655
 656     p = NULL;
 657     t = strtok_r(s, " \t", &p);
 658     if (t == NULL) {
 659         kdc_log(context, config, 0, "Malformed HTTP request from %s", d->addr_string);
 660         return -1;
 661     }
 662     t = strtok_r(NULL, " \t", &p);
 663     if(t == NULL) {
 664         kdc_log(context, config, 0, "Malformed HTTP request from %s", d->addr_string);
 665         return -1;
 666     }
 667     data = malloc(strlen(t));
 668     if (data == NULL) {
 669         kdc_log(context, config, 0, "Failed to allocate %lu bytes",
 670                 (unsigned long)strlen(t));
 671         return -1;
 672     }
 673     if(*t == '/')
 674         t++;
 675     if(de_http(t) != 0) {
 676         kdc_log(context, config, 0, "Malformed HTTP request from %s", d->addr_string);
 677         kdc_log(context, config, 5, "HTTP request: %s", t);
 678         free(data);
 679         return -1;
 680     }
 681     proto = strtok_r(NULL, " \t", &p);
 682     if (proto == NULL) {
 683         kdc_log(context, config, 0, "Malformed HTTP request from %s", d->addr_string);
 684         free(data);
 685         return -1;
 686     }
 687     len = base64_decode(t, data);
 688     if(len <= 0){
 689         const char *msg =
 690             " 404 Not found\r\n"
 691             "Server: Heimdal/" VERSION "\r\n"
 692             "Cache-Control: no-cache\r\n"
 693             "Pragma: no-cache\r\n"
 694             "Content-type: text/html\r\n"
 695             "Content-transfer-encoding: 8bit\r\n\r\n"
 696             "<TITLE>404 Not found</TITLE>\r\n"
 697             "<H1>404 Not found</H1>\r\n"
 698             "That page doesn't exist, maybe you are looking for "
 699             "<A HREF=\"http://www.h5l.org/\">Heimdal</A>?\r\n";
 700         kdc_log(context, config, 0, "HTTP request from %s is non KDC request", d->addr_string);
 701         kdc_log(context, config, 5, "HTTP request: %s", t);
 702         free(data);
 703         if (write(d->s, proto, strlen(proto)) < 0) {
 704             kdc_log(context, config, 0, "HTTP write failed: %s: %s",
 705                     d->addr_string, strerror(errno));
 706             return -1;
 707         }
 708         if (write(d->s, msg, strlen(msg)) < 0) {
 709             kdc_log(context, config, 0, "HTTP write failed: %s: %s",
 710                     d->addr_string, strerror(errno));
 711             return -1;
 712         }
 713         return -1;
 714     }
 715     {
 716         const char *msg =
 717             " 200 OK\r\n"
 718             "Server: Heimdal/" VERSION "\r\n"
 719             "Cache-Control: no-cache\r\n"
 720             "Pragma: no-cache\r\n"
 721             "Content-type: application/octet-stream\r\n"
 722             "Content-transfer-encoding: binary\r\n\r\n";
 723         if (write(d->s, proto, strlen(proto)) < 0) {
 724             kdc_log(context, config, 0, "HTTP write failed: %s: %s",
 725                     d->addr_string, strerror(errno));
 726             return -1;
 727         }
 728         if (write(d->s, msg, strlen(msg)) < 0) {
 729             kdc_log(context, config, 0, "HTTP write failed: %s: %s",
 730                     d->addr_string, strerror(errno));
 731             return -1;
 732         }
 733     }
 734     memcpy(d->buf, data, len);
 735     d->len = len;
 736     free(data);
 737     return 1;
 738 }
 739
 740 /*
 741  * Handle incoming data to the TCP socket in `d[index]'
 742  */
 743
 744 static void
 745 handle_tcp(krb5_context context,
 746            krb5_kdc_configuration *config,
 747            struct descr *d, int idx, int min_free)
 748 {
 749     unsigned char buf[1024];
 750     int n;
 751     int ret = 0;
 752
 753     if (d[idx].timeout == 0) {
 754         add_new_tcp (context, config, d, idx, min_free);
 755         return;
 756     }
 757
 758     n = recvfrom(d[idx].s, buf, sizeof(buf), 0, NULL, NULL);
 759     if(n < 0){
 760         krb5_warn(context, errno, "recvfrom failed from %s to %s/%d",
 761                   d[idx].addr_string, descr_type(d + idx),
 762                   ntohs(d[idx].port));
 763         return;
 764     } else if (n == 0) {
 765         krb5_warnx(context, "connection closed before end of data after %lu "
 766                    "bytes from %s to %s/%d", (unsigned long)d[idx].len,
 767                    d[idx].addr_string, descr_type(d + idx),
 768                    ntohs(d[idx].port));
 769         clear_descr (d + idx);
 770         return;
 771     }
 772     if (grow_descr (context, config, &d[idx], n))
 773         return;
 774     memcpy(d[idx].buf + d[idx].len, buf, n);
 775     d[idx].len += n;
 776     if(d[idx].len > 4 && d[idx].buf[0] == 0) {
 777         ret = handle_vanilla_tcp (context, config, &d[idx]);
 778     } else if(enable_http &&
 779               d[idx].len >= 4 &&
 780               strncmp((char *)d[idx].buf, "GET ", 4) == 0 &&
 781               strncmp((char *)d[idx].buf + d[idx].len - 4,
 782                       "\r\n\r\n", 4) == 0) {
 783         ret = handle_http_tcp (context, config, &d[idx]);
 784         if (ret < 0)
 785             clear_descr (d + idx);
 786     } else if (d[idx].len > 4) {
 787         kdc_log (context, config,
 788                  0, "TCP data of strange type from %s to %s/%d",
 789                  d[idx].addr_string, descr_type(d + idx),
 790                  ntohs(d[idx].port));
 791         if (d[idx].buf[0] & 0x80) {
 792             krb5_data reply;
 793
 794             kdc_log (context, config, 0, "TCP extension not supported");
 795
 796             ret = krb5_mk_error(context,
 797                                 KRB5KRB_ERR_FIELD_TOOLONG,
 798                                 NULL,
 799                                 NULL,
 800                                 NULL,
 801                                 NULL,
 802                                 NULL,
 803                                 NULL,
 804                                 &reply);
 805             if (ret == 0) {
 806                 send_reply(context, config, TRUE, d + idx, &reply);
 807                 krb5_data_free(&reply);
 808             }
 809         }
 810         clear_descr(d + idx);
 811         return;
 812     }
 813     if (ret < 0)
 814         return;
 815     else if (ret == 1) {
 816         do_request(context, config,
 817                    d[idx].buf, d[idx].len, TRUE, &d[idx]);
 818         clear_descr(d + idx);
 819     }
 820 }
 821
 822 void
 823 loop(krb5_context context,
 824      krb5_kdc_configuration *config)
 825 {
 826     struct descr *d;
 827     int ndescr;
 828
 829     ndescr = init_sockets(context, config, &d);
 830     if(ndescr <= 0)
 831         krb5_errx(context, 1, "No sockets!");
 832     kdc_log(context, config, 0, "KDC started");
 833     while(exit_flag == 0){
 834         struct timeval tmout;
 835         fd_set fds;
 836         int min_free = -1;
 837         int max_fd = 0;
 838         int i;
 839
 840         FD_ZERO(&fds);
 841         for(i = 0; i < ndescr; i++) {
 842             if(d[i].s >= 0){
 843                 if(d[i].type == SOCK_STREAM &&
 844                    d[i].timeout && d[i].timeout < time(NULL)) {
 845                     kdc_log(context, config, 1,
 846                             "TCP-connection from %s expired after %lu bytes",
 847                             d[i].addr_string, (unsigned long)d[i].len);
 848                     clear_descr(&d[i]);
 849                     continue;
 850                 }
 851                 if(max_fd < d[i].s)
 852                     max_fd = d[i].s;
 853                 if (max_fd >= FD_SETSIZE)
 854                     krb5_errx(context, 1, "fd too large");
 855                 FD_SET(d[i].s, &fds);
 856             } else if(min_free < 0 || i < min_free)
 857                 min_free = i;
 858         }
 859         if(min_free == -1){
 860             struct descr *tmp;
 861             tmp = realloc(d, (ndescr + 4) * sizeof(*d));
 862             if(tmp == NULL)
 863                 krb5_warnx(context, "No memory");
 864             else {
 865                 d = tmp;
 866                 reinit_descrs (d, ndescr);
 867                 memset(d + ndescr, 0, 4 * sizeof(*d));
 868                 for(i = ndescr; i < ndescr + 4; i++)
 869                     init_descr (&d[i]);
 870                 min_free = ndescr;
 871                 ndescr += 4;
 872             }
 873         }
 874
 875         tmout.tv_sec = TCP_TIMEOUT;
 876         tmout.tv_usec = 0;
 877         switch(select(max_fd + 1, &fds, 0, 0, &tmout)){
 878         case 0:
 879             break;
 880         case -1:
 881             if (errno != EINTR)
 882                 krb5_warn(context, errno, "select");
 883             break;
 884         default:
 885             for(i = 0; i < ndescr; i++)
 886                 if(d[i].s >= 0 && FD_ISSET(d[i].s, &fds)) {
 887                     if(d[i].type == SOCK_DGRAM)
 888                         handle_udp(context, config, &d[i]);
 889                     else if(d[i].type == SOCK_STREAM)
 890                         handle_tcp(context, config, d, i, min_free);
 891                 }
 892         }
 893     }
 894     if(exit_flag == SIGXCPU)
 895         kdc_log(context, config, 0, "CPU time limit exceeded");
 896     else if(exit_flag == SIGINT || exit_flag == SIGTERM)
 897         kdc_log(context, config, 0, "Terminated");
 898     else
 899         kdc_log(context, config, 0, "Unexpected exit reason: %d", exit_flag);
 900     free (d);
 901 }