crypto/heimdal-0.6.3/kdc/connect.c

   1 /*
   2  * Copyright (c) 1997-2004 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("$Id: connect.c,v 1.90.2.2 2004/04/02 20:50:53 lha Exp $");
  37
  38 /*
  39  * a tuple describing on what to listen
  40  */
  41
  42 struct port_desc{
  43     int family;
  44     int type;
  45     int port;
  46 };
  47
  48 /* the current ones */
  49
  50 static struct port_desc *ports;
  51 static int num_ports;
  52
  53 /*
  54  * add `family, port, protocol' to the list with duplicate suppresion.
  55  */
  56
  57 static void
  58 add_port(int family, int port, const char *protocol)
  59 {
  60     int type;
  61     int i;
  62
  63     if(strcmp(protocol, "udp") == 0)
  64         type = SOCK_DGRAM;
  65     else if(strcmp(protocol, "tcp") == 0)
  66         type = SOCK_STREAM;
  67     else
  68         return;
  69     for(i = 0; i < num_ports; i++){
  70         if(ports[i].type == type
  71            && ports[i].port == port
  72            && ports[i].family == family)
  73             return;
  74     }
  75     ports = realloc(ports, (num_ports + 1) * sizeof(*ports));
  76     if (ports == NULL)
  77         krb5_err (context, 1, errno, "realloc");
  78     ports[num_ports].family = family;
  79     ports[num_ports].type   = type;
  80     ports[num_ports].port   = port;
  81     num_ports++;
  82 }
  83
  84 /*
  85  * add a triple but with service -> port lookup
  86  * (this prints warnings for stuff that does not exist)
  87  */
  88
  89 static void
  90 add_port_service(int family, const char *service, int port,
  91                  const char *protocol)
  92 {
  93     port = krb5_getportbyname (context, service, protocol, port);
  94     add_port (family, port, protocol);
  95 }
  96
  97 /*
  98  * add the port with service -> port lookup or string -> number
  99  * (no warning is printed)
 100  */
 101
 102 static void
 103 add_port_string (int family, const char *port_str, const char *protocol)
 104 {
 105     struct servent *sp;
 106     int port;
 107
 108     sp = roken_getservbyname (port_str, protocol);
 109     if (sp != NULL) {
 110         port = sp->s_port;
 111     } else {
 112         char *end;
 113
 114         port = htons(strtol(port_str, &end, 0));
 115         if (end == port_str)
 116             return;
 117     }
 118     add_port (family, port, protocol);
 119 }
 120
 121 /*
 122  * add the standard collection of ports for `family'
 123  */
 124
 125 static void
 126 add_standard_ports (int family)
 127 {
 128     add_port_service(family, "kerberos", 88, "udp");
 129     add_port_service(family, "kerberos", 88, "tcp");
 130     add_port_service(family, "kerberos-sec", 88, "udp");
 131     add_port_service(family, "kerberos-sec", 88, "tcp");
 132     if(enable_http)
 133         add_port_service(family, "http", 80, "tcp");
 134     if(enable_524) {
 135         add_port_service(family, "krb524", 4444, "udp");
 136         add_port_service(family, "krb524", 4444, "tcp");
 137     }
 138 #ifdef KRB4
 139     if(enable_v4) {
 140         add_port_service(family, "kerberos-iv", 750, "udp");
 141         add_port_service(family, "kerberos-iv", 750, "tcp");
 142     }
 143     if (enable_kaserver)
 144         add_port_service(family, "afs3-kaserver", 7004, "udp");
 145 #endif
 146 }
 147
 148 /*
 149  * parse the set of space-delimited ports in `str' and add them.
 150  * "+" => all the standard ones
 151  * otherwise it's port|service[/protocol]
 152  */
 153
 154 static void
 155 parse_ports(const char *str)
 156 {
 157     char *pos = NULL;
 158     char *p;
 159     char *str_copy = strdup (str);
 160
 161     p = strtok_r(str_copy, " \t", &pos);
 162     while(p != NULL) {
 163         if(strcmp(p, "+") == 0) {
 164 #ifdef HAVE_IPV6
 165             add_standard_ports(AF_INET6);
 166 #endif
 167             add_standard_ports(AF_INET);
 168         } else {
 169             char *q = strchr(p, '/');
 170             if(q){
 171                 *q++ = 0;
 172 #ifdef HAVE_IPV6
 173                 add_port_string(AF_INET6, p, q);
 174 #endif
 175                 add_port_string(AF_INET, p, q);
 176             }else {
 177 #ifdef HAVE_IPV6
 178                 add_port_string(AF_INET6, p, "udp");
 179                 add_port_string(AF_INET6, p, "tcp");
 180 #endif
 181                 add_port_string(AF_INET, p, "udp");
 182                 add_port_string(AF_INET, p, "tcp");
 183             }
 184         }
 185
 186         p = strtok_r(NULL, " \t", &pos);
 187     }
 188     free (str_copy);
 189 }
 190
 191 /*
 192  * every socket we listen on
 193  */
 194
 195 struct descr {
 196     int s;
 197     int type;
 198     unsigned char *buf;
 199     size_t size;
 200     size_t len;
 201     time_t timeout;
 202     struct sockaddr_storage __ss;
 203     struct sockaddr *sa;
 204     socklen_t sock_len;
 205     char addr_string[128];
 206 };
 207
 208 static void
 209 init_descr(struct descr *d)
 210 {
 211     memset(d, 0, sizeof(*d));
 212     d->sa = (struct sockaddr *)&d->__ss;
 213     d->s = -1;
 214 }
 215
 216 /*
 217  * re-initialize all `n' ->sa in `d'.
 218  */
 219
 220 static void
 221 reinit_descrs (struct descr *d, int n)
 222 {
 223     int i;
 224
 225     for (i = 0; i < n; ++i)
 226         d[i].sa = (struct sockaddr *)&d[i].__ss;
 227 }
 228
 229 /*
 230  * Create the socket (family, type, port) in `d'
 231  */
 232
 233 static void
 234 init_socket(struct descr *d, krb5_address *a, int family, int type, int port)
 235 {
 236     krb5_error_code ret;
 237     struct sockaddr_storage __ss;
 238     struct sockaddr *sa = (struct sockaddr *)&__ss;
 239     int sa_size = sizeof(__ss);
 240
 241     init_descr (d);
 242
 243     ret = krb5_addr2sockaddr (context, a, sa, &sa_size, port);
 244     if (ret) {
 245         krb5_warn(context, ret, "krb5_addr2sockaddr");
 246         close(d->s);
 247         d->s = -1;
 248         return;
 249     }
 250
 251     if (sa->sa_family != family)
 252         return;
 253
 254     d->s = socket(family, type, 0);
 255     if(d->s < 0){
 256         krb5_warn(context, errno, "socket(%d, %d, 0)", family, type);
 257         d->s = -1;
 258         return;
 259     }
 260 #if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_REUSEADDR)
 261     {
 262         int one = 1;
 263         setsockopt(d->s, SOL_SOCKET, SO_REUSEADDR, (void *)&one, sizeof(one));
 264     }
 265 #endif
 266     d->type = type;
 267
 268     if(bind(d->s, sa, sa_size) < 0){
 269         char a_str[256];
 270         size_t len;
 271
 272         krb5_print_address (a, a_str, sizeof(a_str), &len);
 273         krb5_warn(context, errno, "bind %s/%d", a_str, ntohs(port));
 274         close(d->s);
 275         d->s = -1;
 276         return;
 277     }
 278     if(type == SOCK_STREAM && listen(d->s, SOMAXCONN) < 0){
 279         char a_str[256];
 280         size_t len;
 281
 282         krb5_print_address (a, a_str, sizeof(a_str), &len);
 283         krb5_warn(context, errno, "listen %s/%d", a_str, ntohs(port));
 284         close(d->s);
 285         d->s = -1;
 286         return;
 287     }
 288 }
 289
 290 /*
 291  * Allocate descriptors for all the sockets that we should listen on
 292  * and return the number of them.
 293  */
 294
 295 static int
 296 init_sockets(struct descr **desc)
 297 {
 298     krb5_error_code ret;
 299     int i, j;
 300     struct descr *d;
 301     int num = 0;
 302     krb5_addresses addresses;
 303
 304     if (explicit_addresses.len) {
 305         addresses = explicit_addresses;
 306     } else {
 307         ret = krb5_get_all_server_addrs (context, &addresses);
 308         if (ret)
 309             krb5_err (context, 1, ret, "krb5_get_all_server_addrs");
 310     }
 311     parse_ports(port_str);
 312     d = malloc(addresses.len * num_ports * sizeof(*d));
 313     if (d == NULL)
 314         krb5_errx(context, 1, "malloc(%lu) failed",
 315                   (unsigned long)num_ports * sizeof(*d));
 316
 317     for (i = 0; i < num_ports; i++){
 318         for (j = 0; j < addresses.len; ++j) {
 319             init_socket(&d[num], &addresses.val[j],
 320                         ports[i].family, ports[i].type, ports[i].port);
 321             if(d[num].s != -1){
 322                 char a_str[80];
 323                 size_t len;
 324
 325                 krb5_print_address (&addresses.val[j], a_str,
 326                                     sizeof(a_str), &len);
 327
 328                 kdc_log(5, "listening on %s port %u/%s",
 329                         a_str,
 330                         ntohs(ports[i].port),
 331                         (ports[i].type == SOCK_STREAM) ? "tcp" : "udp");
 332                 /* XXX */
 333                 num++;
 334             }
 335         }
 336     }
 337     krb5_free_addresses (context, &addresses);
 338     d = realloc(d, num * sizeof(*d));
 339     if (d == NULL && num != 0)
 340         krb5_errx(context, 1, "realloc(%lu) failed",
 341                   (unsigned long)num * sizeof(*d));
 342     reinit_descrs (d, num);
 343     *desc = d;
 344     return num;
 345 }
 346
 347 /*
 348  * handle the request in `buf, len', from `addr' (or `from' as a string),
 349  * sending a reply in `reply'.
 350  */
 351
 352 static int
 353 process_request(unsigned char *buf,
 354                 size_t len,
 355                 krb5_data *reply,
 356                 int *sendlength,
 357                 const char *from,
 358                 struct sockaddr *addr)
 359 {
 360     KDC_REQ req;
 361     Ticket ticket;
 362     krb5_error_code ret;
 363     size_t i;
 364
 365     gettimeofday(&now, NULL);
 366     if(decode_AS_REQ(buf, len, &req, &i) == 0){
 367         ret = as_rep(&req, reply, from, addr);
 368         free_AS_REQ(&req);
 369         return ret;
 370     }else if(decode_TGS_REQ(buf, len, &req, &i) == 0){
 371         ret = tgs_rep(&req, reply, from, addr);
 372         free_TGS_REQ(&req);
 373         return ret;
 374     }else if(decode_Ticket(buf, len, &ticket, &i) == 0){
 375         ret = do_524(&ticket, reply, from, addr);
 376         free_Ticket(&ticket);
 377         return ret;
 378 #ifdef KRB4
 379     } else if(maybe_version4(buf, len)){
 380         *sendlength = 0; /* elbitapmoc sdrawkcab XXX */
 381         do_version4(buf, len, reply, from, (struct sockaddr_in*)addr);
 382         return 0;
 383     } else if (enable_kaserver) {
 384         ret = do_kaserver (buf, len, reply, from, (struct sockaddr_in*)addr);
 385         return ret;
 386 #endif
 387     }
 388
 389     return -1;
 390 }
 391
 392 static void
 393 addr_to_string(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  * Handle the request in `buf, len' to socket `d'
 408  */
 409
 410 static void
 411 do_request(void *buf, size_t len, int sendlength,
 412            struct descr *d)
 413 {
 414     krb5_error_code ret;
 415     krb5_data reply;
 416
 417     reply.length = 0;
 418     ret = process_request(buf, len, &reply, &sendlength,
 419                           d->addr_string, d->sa);
 420     if(reply.length){
 421         kdc_log(5, "sending %lu bytes to %s", (unsigned long)reply.length,
 422                 d->addr_string);
 423         if(sendlength){
 424             unsigned char len[4];
 425             len[0] = (reply.length >> 24) & 0xff;
 426             len[1] = (reply.length >> 16) & 0xff;
 427             len[2] = (reply.length >> 8) & 0xff;
 428             len[3] = reply.length & 0xff;
 429             if(sendto(d->s, len, sizeof(len), 0, d->sa, d->sock_len) < 0) {
 430                 kdc_log (0, "sendto(%s): %s", d->addr_string, strerror(errno));
 431                 krb5_data_free(&reply);
 432                 return;
 433             }
 434         }
 435         if(sendto(d->s, reply.data, reply.length, 0, d->sa, d->sock_len) < 0) {
 436             kdc_log (0, "sendto(%s): %s", d->addr_string, strerror(errno));
 437             krb5_data_free(&reply);
 438             return;
 439         }
 440         krb5_data_free(&reply);
 441     }
 442     if(ret)
 443         kdc_log(0, "Failed processing %lu byte request from %s",
 444                 (unsigned long)len, d->addr_string);
 445 }
 446
 447 /*
 448  * Handle incoming data to the UDP socket in `d'
 449  */
 450
 451 static void
 452 handle_udp(struct descr *d)
 453 {
 454     unsigned char *buf;
 455     int n;
 456
 457     buf = malloc(max_request);
 458     if(buf == NULL){
 459         kdc_log(0, "Failed to allocate %lu bytes", (unsigned long)max_request);
 460         return;
 461     }
 462
 463     d->sock_len = sizeof(d->__ss);
 464     n = recvfrom(d->s, buf, max_request, 0, d->sa, &d->sock_len);
 465     if(n < 0)
 466         krb5_warn(context, errno, "recvfrom");
 467     else {
 468         addr_to_string (d->sa, d->sock_len,
 469                         d->addr_string, sizeof(d->addr_string));
 470         do_request(buf, n, 0, d);
 471     }
 472     free (buf);
 473 }
 474
 475 static void
 476 clear_descr(struct descr *d)
 477 {
 478     if(d->buf)
 479         memset(d->buf, 0, d->size);
 480     d->len = 0;
 481     if(d->s != -1)
 482         close(d->s);
 483     d->s = -1;
 484 }
 485
 486
 487 /* remove HTTP %-quoting from buf */
 488 static int
 489 de_http(char *buf)
 490 {
 491     char *p, *q;
 492     for(p = q = buf; *p; p++, q++) {
 493         if(*p == '%' && isxdigit(p[1]) && isxdigit(p[2])) {
 494             unsigned int x;
 495             if(sscanf(p + 1, "%2x", &x) != 1)
 496                 return -1;
 497             *q = x;
 498             p += 2;
 499         } else
 500             *q = *p;
 501     }
 502     *q = '\0';
 503     return 0;
 504 }
 505
 506 #define TCP_TIMEOUT 4
 507
 508 /*
 509  * accept a new TCP connection on `d[parent]' and store it in `d[child]'
 510  */
 511
 512 static void
 513 add_new_tcp (struct descr *d, int parent, int child)
 514 {
 515     int s;
 516
 517     if (child == -1)
 518         return;
 519
 520     d[child].sock_len = sizeof(d[child].__ss);
 521     s = accept(d[parent].s, d[child].sa, &d[child].sock_len);
 522     if(s < 0) {
 523         krb5_warn(context, errno, "accept");
 524         return;
 525     }
 526
 527     if (s >= FD_SETSIZE) {
 528         krb5_warnx(context, "socket FD too large");
 529         close (s);
 530         return;
 531     }
 532
 533     d[child].s = s;
 534     d[child].timeout = time(NULL) + TCP_TIMEOUT;
 535     d[child].type = SOCK_STREAM;
 536     addr_to_string (d[child].sa, d[child].sock_len,
 537                     d[child].addr_string, sizeof(d[child].addr_string));
 538 }
 539
 540 /*
 541  * Grow `d' to handle at least `n'.
 542  * Return != 0 if fails
 543  */
 544
 545 static int
 546 grow_descr (struct descr *d, size_t n)
 547 {
 548     if (d->size - d->len < n) {
 549         unsigned char *tmp;
 550         size_t grow;
 551
 552         grow = max(1024, d->len + n);
 553         if (d->size + grow > max_request) {
 554             kdc_log(0, "Request exceeds max request size (%lu bytes).",
 555                     (unsigned long)d->size + grow);
 556             clear_descr(d);
 557             return -1;
 558         }
 559         tmp = realloc (d->buf, d->size + grow);
 560         if (tmp == NULL) {
 561             kdc_log(0, "Failed to re-allocate %lu bytes.",
 562                     (unsigned long)d->size + grow);
 563             clear_descr(d);
 564             return -1;
 565         }
 566         d->size += grow;
 567         d->buf = tmp;
 568     }
 569     return 0;
 570 }
 571
 572 /*
 573  * Try to handle the TCP data at `d->buf, d->len'.
 574  * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 575  */
 576
 577 static int
 578 handle_vanilla_tcp (struct descr *d)
 579 {
 580     krb5_storage *sp;
 581     int32_t len;
 582
 583     sp = krb5_storage_from_mem(d->buf, d->len);
 584     if (sp == NULL) {
 585         kdc_log (0, "krb5_storage_from_mem failed");
 586         return -1;
 587     }
 588     krb5_ret_int32(sp, &len);
 589     krb5_storage_free(sp);
 590     if(d->len - 4 >= len) {
 591         memmove(d->buf, d->buf + 4, d->len - 4);
 592         return 1;
 593     }
 594     return 0;
 595 }
 596
 597 /*
 598  * Try to handle the TCP/HTTP data at `d->buf, d->len'.
 599  * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 600  */
 601
 602 static int
 603 handle_http_tcp (struct descr *d)
 604 {
 605     char *s, *p, *t;
 606     void *data;
 607     char *proto;
 608     int len;
 609
 610     s = (char *)d->buf;
 611
 612     p = strstr(s, "\r\n");
 613     if (p == NULL) {
 614         kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
 615         return -1;
 616     }
 617     *p = 0;
 618
 619     p = NULL;
 620     t = strtok_r(s, " \t", &p);
 621     if (t == NULL) {
 622         kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
 623         return -1;
 624     }
 625     t = strtok_r(NULL, " \t", &p);
 626     if(t == NULL) {
 627         kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
 628         return -1;
 629     }
 630     data = malloc(strlen(t));
 631     if (data == NULL) {
 632         kdc_log(0, "Failed to allocate %lu bytes",
 633                 (unsigned long)strlen(t));
 634         return -1;
 635     }
 636     if(*t == '/')
 637         t++;
 638     if(de_http(t) != 0) {
 639         kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
 640         kdc_log(5, "Request: %s", t);
 641         free(data);
 642         return -1;
 643     }
 644     proto = strtok_r(NULL, " \t", &p);
 645     if (proto == NULL) {
 646         kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
 647         free(data);
 648         return -1;
 649     }
 650     len = base64_decode(t, data);
 651     if(len <= 0){
 652         const char *msg =
 653             " 404 Not found\r\n"
 654             "Server: Heimdal/" VERSION "\r\n"
 655             "Cache-Control: no-cache\r\n"
 656             "Pragma: no-cache\r\n"
 657             "Content-type: text/html\r\n"
 658             "Content-transfer-encoding: 8bit\r\n\r\n"
 659             "<TITLE>404 Not found</TITLE>\r\n"
 660             "<H1>404 Not found</H1>\r\n"
 661             "That page doesn't exist, maybe you are looking for "
 662             "<A HREF=\"http://www.pdc.kth.se/heimdal/\">Heimdal</A>?\r\n";
 663         write(d->s, proto, strlen(proto));
 664         write(d->s, msg, strlen(msg));
 665         kdc_log(0, "HTTP request from %s is non KDC request", d->addr_string);
 666         kdc_log(5, "Request: %s", t);
 667         free(data);
 668         return -1;
 669     }
 670     {
 671         const char *msg =
 672             " 200 OK\r\n"
 673             "Server: Heimdal/" VERSION "\r\n"
 674             "Cache-Control: no-cache\r\n"
 675             "Pragma: no-cache\r\n"
 676             "Content-type: application/octet-stream\r\n"
 677             "Content-transfer-encoding: binary\r\n\r\n";
 678         write(d->s, proto, strlen(proto));
 679         write(d->s, msg, strlen(msg));
 680     }
 681     memcpy(d->buf, data, len);
 682     d->len = len;
 683     free(data);
 684     return 1;
 685 }
 686
 687 /*
 688  * Handle incoming data to the TCP socket in `d[index]'
 689  */
 690
 691 static void
 692 handle_tcp(struct descr *d, int index, int min_free)
 693 {
 694     unsigned char buf[1024];
 695     int n;
 696     int ret = 0;
 697
 698     if (d[index].timeout == 0) {
 699         add_new_tcp (d, index, min_free);
 700         return;
 701     }
 702
 703     n = recvfrom(d[index].s, buf, sizeof(buf), 0, NULL, NULL);
 704     if(n < 0){
 705         krb5_warn(context, errno, "recvfrom");
 706         return;
 707     } else if (n == 0) {
 708         krb5_warnx(context, "connection closed before end of data after %lu "
 709                    "bytes from %s",
 710                    (unsigned long)d[index].len, d[index].addr_string);
 711         clear_descr (d + index);
 712         return;
 713     }
 714     if (grow_descr (&d[index], n))
 715         return;
 716     memcpy(d[index].buf + d[index].len, buf, n);
 717     d[index].len += n;
 718     if(d[index].len > 4 && d[index].buf[0] == 0) {
 719         ret = handle_vanilla_tcp (&d[index]);
 720     } else if(enable_http &&
 721               d[index].len >= 4 &&
 722               strncmp((char *)d[index].buf, "GET ", 4) == 0 &&
 723               strncmp((char *)d[index].buf + d[index].len - 4,
 724                       "\r\n\r\n", 4) == 0) {
 725         ret = handle_http_tcp (&d[index]);
 726         if (ret < 0)
 727             clear_descr (d + index);
 728     } else if (d[index].len > 4) {
 729         kdc_log (0, "TCP data of strange type from %s", d[index].addr_string);
 730         return;
 731     }
 732     if (ret < 0)
 733         return;
 734     else if (ret == 1) {
 735         do_request(d[index].buf, d[index].len, 1, &d[index]);
 736         clear_descr(d + index);
 737     }
 738 }
 739
 740 void
 741 loop(void)
 742 {
 743     struct descr *d;
 744     int ndescr;
 745
 746     ndescr = init_sockets(&d);
 747     if(ndescr <= 0)
 748         krb5_errx(context, 1, "No sockets!");
 749     while(exit_flag == 0){
 750         struct timeval tmout;
 751         fd_set fds;
 752         int min_free = -1;
 753         int max_fd = 0;
 754         int i;
 755
 756         FD_ZERO(&fds);
 757         for(i = 0; i < ndescr; i++) {
 758             if(d[i].s >= 0){
 759                 if(d[i].type == SOCK_STREAM &&
 760                    d[i].timeout && d[i].timeout < time(NULL)) {
 761                     kdc_log(1, "TCP-connection from %s expired after %lu bytes",
 762                             d[i].addr_string, (unsigned long)d[i].len);
 763                     clear_descr(&d[i]);
 764                     continue;
 765                 }
 766                 if(max_fd < d[i].s)
 767                     max_fd = d[i].s;
 768                 if (max_fd >= FD_SETSIZE)
 769                     krb5_errx(context, 1, "fd too large");
 770                 FD_SET(d[i].s, &fds);
 771             } else if(min_free < 0 || i < min_free)
 772                 min_free = i;
 773         }
 774         if(min_free == -1){
 775             struct descr *tmp;
 776             tmp = realloc(d, (ndescr + 4) * sizeof(*d));
 777             if(tmp == NULL)
 778                 krb5_warnx(context, "No memory");
 779             else {
 780                 d = tmp;
 781                 reinit_descrs (d, ndescr);
 782                 memset(d + ndescr, 0, 4 * sizeof(*d));
 783                 for(i = ndescr; i < ndescr + 4; i++)
 784                     init_descr (&d[i]);
 785                 min_free = ndescr;
 786                 ndescr += 4;
 787             }
 788         }
 789
 790         tmout.tv_sec = TCP_TIMEOUT;
 791         tmout.tv_usec = 0;
 792         switch(select(max_fd + 1, &fds, 0, 0, &tmout)){
 793         case 0:
 794             break;
 795         case -1:
 796             if (errno != EINTR)
 797                 krb5_warn(context, errno, "select");
 798             break;
 799         default:
 800             for(i = 0; i < ndescr; i++)
 801                 if(d[i].s >= 0 && FD_ISSET(d[i].s, &fds)) {
 802                     if(d[i].type == SOCK_DGRAM)
 803                         handle_udp(&d[i]);
 804                     else if(d[i].type == SOCK_STREAM)
 805                         handle_tcp(d, i, min_free);
 806                 }
 807         }
 808     }
 809     free (d);
 810 }