xref: /minix3/crypto/external/bsd/heimdal/dist/lib/krb5/send_to_kdc.c (revision 0a6a1f1d05b60e214de2f05a7310ddd1f0e590e7)
1 /*	$NetBSD: send_to_kdc.c,v 1.3 2014/05/12 18:46:27 christos Exp $	*/
2 
3 /*
4  * Copyright (c) 1997 - 2002 Kungliga Tekniska Högskolan
5  * (Royal Institute of Technology, Stockholm, Sweden).
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  *
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * 3. Neither the name of the Institute nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include "krb5_locl.h"
37 #include "send_to_kdc_plugin.h"
38 
39 struct send_to_kdc {
40     krb5_send_to_kdc_func func;
41     void *data;
42 };
43 
44 /*
45  * connect to a remote host and in the case of stream sockets, provide
46  * a timeout for the connexion.
47  */
48 
49 static int
timed_connect(int s,struct addrinfo * addr,time_t tmout)50 timed_connect(int s, struct addrinfo *addr, time_t tmout)
51 {
52 #ifdef HAVE_POLL
53     socklen_t sl;
54     int err;
55     int flags;
56     int ret;
57 
58     if (addr->ai_socktype != SOCK_STREAM)
59 	return connect(s, addr->ai_addr, addr->ai_addrlen);
60 
61     flags = fcntl(s, F_GETFL);
62     if (flags == -1)
63 	return -1;
64 
65     if (fcntl(s, F_SETFL, flags | O_NONBLOCK) == -1)
66 	return -1;
67     ret = connect(s, addr->ai_addr, addr->ai_addrlen);
68     if (ret == -1 && errno != EINPROGRESS)
69 	return -1;
70 
71     for (;;) {
72 	struct pollfd fds;
73 
74 	fds.fd = s;
75 	fds.events = POLLIN | POLLOUT;
76 	fds.revents = 0;
77 
78 	ret = poll(&fds, 1, tmout * 1000);
79 	if (ret != -1 || errno != EINTR)
80 	    break;
81     }
82     if (fcntl(s, F_SETFL, flags) == -1)
83 	return -1;
84 
85     if (ret != 1)
86 	return -1;
87 
88     sl = sizeof(err);
89     ret = getsockopt(s, SOL_SOCKET, SO_ERROR, &err, &sl);
90     if (ret == -1)
91 	return -1;
92     if (err != 0)
93 	return -1;
94 
95     return 0;
96 #else
97     return connect(s, addr->ai_addr, addr->ai_addrlen);
98 #endif
99 }
100 
101 /*
102  * send the data in `req' on the socket `fd' (which is datagram iff udp)
103  * waiting `tmout' for a reply and returning the reply in `rep'.
104  * iff limit read up to this many bytes
105  * returns 0 and data in `rep' if succesful, otherwise -1
106  */
107 
108 static int
recv_loop(krb5_socket_t fd,time_t tmout,int udp,size_t limit,krb5_data * rep)109 recv_loop (krb5_socket_t fd,
110 	   time_t tmout,
111 	   int udp,
112 	   size_t limit,
113 	   krb5_data *rep)
114 {
115      fd_set fdset;
116      struct timeval timeout;
117      int ret;
118      int nbytes;
119 
120 #ifndef NO_LIMIT_FD_SETSIZE
121      if (fd >= FD_SETSIZE) {
122 	 return -1;
123      }
124 #endif
125 
126      krb5_data_zero(rep);
127      do {
128 	 FD_ZERO(&fdset);
129 	 FD_SET(fd, &fdset);
130 	 timeout.tv_sec  = tmout;
131 	 timeout.tv_usec = 0;
132 	 ret = select (fd + 1, &fdset, NULL, NULL, &timeout);
133 	 if (ret < 0) {
134 	     if (errno == EINTR)
135 		 continue;
136 	     return -1;
137 	 } else if (ret == 0) {
138 	     return 0;
139 	 } else {
140 	     void *tmp;
141 
142 	     if (rk_SOCK_IOCTL (fd, FIONREAD, &nbytes) < 0) {
143 		 krb5_data_free (rep);
144 		 return -1;
145 	     }
146 	     if(nbytes <= 0)
147 		 return 0;
148 
149 	     if (limit)
150 		 nbytes = min((size_t)nbytes, limit - rep->length);
151 
152 	     tmp = realloc (rep->data, rep->length + nbytes);
153 	     if (tmp == NULL) {
154 		 krb5_data_free (rep);
155 		 return -1;
156 	     }
157 	     rep->data = tmp;
158 	     ret = recv (fd, (char*)tmp + rep->length, nbytes, 0);
159 	     if (ret < 0) {
160 		 krb5_data_free (rep);
161 		 return -1;
162 	     }
163 	     rep->length += ret;
164 	 }
165      } while(!udp && (limit == 0 || rep->length < limit));
166      return 0;
167 }
168 
169 /*
170  * Send kerberos requests and receive a reply on a udp or any other kind
171  * of a datagram socket.  See `recv_loop'.
172  */
173 
174 static int
send_and_recv_udp(krb5_socket_t fd,time_t tmout,const krb5_data * req,krb5_data * rep)175 send_and_recv_udp(krb5_socket_t fd,
176 		  time_t tmout,
177 		  const krb5_data *req,
178 		  krb5_data *rep)
179 {
180     if (send (fd, req->data, req->length, 0) < 0)
181 	return -1;
182 
183     return recv_loop(fd, tmout, 1, 0, rep);
184 }
185 
186 /*
187  * `send_and_recv' for a TCP (or any other stream) socket.
188  * Since there are no record limits on a stream socket the protocol here
189  * is to prepend the request with 4 bytes of its length and the reply
190  * is similarly encoded.
191  */
192 
193 static int
send_and_recv_tcp(krb5_socket_t fd,time_t tmout,const krb5_data * req,krb5_data * rep)194 send_and_recv_tcp(krb5_socket_t fd,
195 		  time_t tmout,
196 		  const krb5_data *req,
197 		  krb5_data *rep)
198 {
199     unsigned char len[4];
200     unsigned long rep_len;
201     krb5_data len_data;
202 
203     _krb5_put_int(len, req->length, 4);
204     if(net_write (fd, len, sizeof(len)) < 0)
205 	return -1;
206     if(net_write (fd, req->data, req->length) < 0)
207 	return -1;
208     if (recv_loop (fd, tmout, 0, 4, &len_data) < 0)
209 	return -1;
210     if (len_data.length != 4) {
211 	krb5_data_free (&len_data);
212 	return -1;
213     }
214     _krb5_get_int(len_data.data, &rep_len, 4);
215     krb5_data_free (&len_data);
216     if (recv_loop (fd, tmout, 0, rep_len, rep) < 0)
217 	return -1;
218     if(rep->length != rep_len) {
219 	krb5_data_free (rep);
220 	return -1;
221     }
222     return 0;
223 }
224 
225 int
_krb5_send_and_recv_tcp(krb5_socket_t fd,time_t tmout,const krb5_data * req,krb5_data * rep)226 _krb5_send_and_recv_tcp(krb5_socket_t fd,
227 			time_t tmout,
228 			const krb5_data *req,
229 			krb5_data *rep)
230 {
231     return send_and_recv_tcp(fd, tmout, req, rep);
232 }
233 
234 /*
235  * `send_and_recv' tailored for the HTTP protocol.
236  */
237 
238 static int
send_and_recv_http(krb5_socket_t fd,time_t tmout,const char * prefix,const krb5_data * req,krb5_data * rep)239 send_and_recv_http(krb5_socket_t fd,
240 		   time_t tmout,
241 		   const char *prefix,
242 		   const krb5_data *req,
243 		   krb5_data *rep)
244 {
245     char *request = NULL;
246     char *str;
247     int ret;
248     int len = base64_encode(req->data, req->length, &str);
249 
250     if(len < 0)
251 	return -1;
252     ret = asprintf(&request, "GET %s%s HTTP/1.0\r\n\r\n", prefix, str);
253     free(str);
254     if (ret < 0 || request == NULL)
255 	return -1;
256     ret = net_write (fd, request, strlen(request));
257     free (request);
258     if (ret < 0)
259 	return ret;
260     ret = recv_loop(fd, tmout, 0, 0, rep);
261     if(ret)
262 	return ret;
263     {
264 	unsigned long rep_len;
265 	char *s, *p;
266 
267 	s = realloc(rep->data, rep->length + 1);
268 	if (s == NULL) {
269 	    krb5_data_free (rep);
270 	    return -1;
271 	}
272 	s[rep->length] = 0;
273 	p = strstr(s, "\r\n\r\n");
274 	if(p == NULL) {
275 	    krb5_data_zero(rep);
276 	    free(s);
277 	    return -1;
278 	}
279 	p += 4;
280 	rep->data = s;
281 	rep->length -= p - s;
282 	if(rep->length < 4) { /* remove length */
283 	    krb5_data_zero(rep);
284 	    free(s);
285 	    return -1;
286 	}
287 	rep->length -= 4;
288 	_krb5_get_int(p, &rep_len, 4);
289 	if (rep_len != rep->length) {
290 	    krb5_data_zero(rep);
291 	    free(s);
292 	    return -1;
293 	}
294 	memmove(rep->data, p + 4, rep->length);
295     }
296     return 0;
297 }
298 
299 static int
init_port(const char * s,int fallback)300 init_port(const char *s, int fallback)
301 {
302     if (s) {
303 	int tmp;
304 
305 	sscanf (s, "%d", &tmp);
306 	return htons(tmp);
307     } else
308 	return fallback;
309 }
310 
311 /*
312  * Return 0 if succesful, otherwise 1
313  */
314 
315 static int
send_via_proxy(krb5_context context,const krb5_krbhst_info * hi,const krb5_data * send_data,krb5_data * receive)316 send_via_proxy (krb5_context context,
317 		const krb5_krbhst_info *hi,
318 		const krb5_data *send_data,
319 		krb5_data *receive)
320 {
321     char *proxy2 = strdup(context->http_proxy);
322     char *proxy  = proxy2;
323     char *prefix = NULL;
324     char *colon;
325     struct addrinfo hints;
326     struct addrinfo *ai, *a;
327     int ret;
328     krb5_socket_t s = rk_INVALID_SOCKET;
329     char portstr[NI_MAXSERV];
330 
331     if (proxy == NULL)
332 	return ENOMEM;
333     if (strncmp (proxy, "http://", 7) == 0)
334 	proxy += 7;
335 
336     colon = strchr(proxy, ':');
337     if(colon != NULL)
338 	*colon++ = '\0';
339     memset (&hints, 0, sizeof(hints));
340     hints.ai_family   = PF_UNSPEC;
341     hints.ai_socktype = SOCK_STREAM;
342     snprintf (portstr, sizeof(portstr), "%d",
343 	      ntohs(init_port (colon, htons(80))));
344     ret = getaddrinfo (proxy, portstr, &hints, &ai);
345     free (proxy2);
346     if (ret)
347 	return krb5_eai_to_heim_errno(ret, errno);
348 
349     for (a = ai; a != NULL; a = a->ai_next) {
350 	s = socket (a->ai_family, a->ai_socktype | SOCK_CLOEXEC, a->ai_protocol);
351 	if (s < 0)
352 	    continue;
353 	rk_cloexec(s);
354 	if (timed_connect (s, a, context->kdc_timeout) < 0) {
355 	    rk_closesocket (s);
356 	    continue;
357 	}
358 	break;
359     }
360     if (a == NULL) {
361 	freeaddrinfo (ai);
362 	return 1;
363     }
364     freeaddrinfo (ai);
365 
366     ret = asprintf(&prefix, "http://%s/", hi->hostname);
367     if(ret < 0 || prefix == NULL) {
368 	close(s);
369 	return 1;
370     }
371     ret = send_and_recv_http(s, context->kdc_timeout,
372 			     prefix, send_data, receive);
373     rk_closesocket (s);
374     free(prefix);
375     if(ret == 0 && receive->length != 0)
376 	return 0;
377     return 1;
378 }
379 
380 static krb5_error_code
send_via_plugin(krb5_context context,krb5_krbhst_info * hi,time_t timeout,const krb5_data * send_data,krb5_data * receive)381 send_via_plugin(krb5_context context,
382 		krb5_krbhst_info *hi,
383 		time_t timeout,
384 		const krb5_data *send_data,
385 		krb5_data *receive)
386 {
387     struct krb5_plugin *list = NULL, *e;
388     krb5_error_code ret;
389 
390     ret = _krb5_plugin_find(context, PLUGIN_TYPE_DATA, KRB5_PLUGIN_SEND_TO_KDC, &list);
391     if(ret != 0 || list == NULL)
392 	return KRB5_PLUGIN_NO_HANDLE;
393 
394     for (e = list; e != NULL; e = _krb5_plugin_get_next(e)) {
395 	krb5plugin_send_to_kdc_ftable *service;
396 	void *ctx;
397 
398 	service = _krb5_plugin_get_symbol(e);
399 	if (service->minor_version != 0)
400 	    continue;
401 
402 	(*service->init)(context, &ctx);
403 	ret = (*service->send_to_kdc)(context, ctx, hi,
404 				      timeout, send_data, receive);
405 	(*service->fini)(ctx);
406 	if (ret == 0)
407 	    break;
408 	if (ret != KRB5_PLUGIN_NO_HANDLE) {
409 	    krb5_set_error_message(context, ret,
410 				   N_("Plugin send_to_kdc failed to "
411 				      "lookup with error: %d", ""), ret);
412 	    break;
413 	}
414     }
415     _krb5_plugin_free(list);
416     return KRB5_PLUGIN_NO_HANDLE;
417 }
418 
419 
420 /*
421  * Send the data `send' to one host from `handle` and get back the reply
422  * in `receive'.
423  */
424 
425 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_sendto(krb5_context context,const krb5_data * send_data,krb5_krbhst_handle handle,krb5_data * receive)426 krb5_sendto (krb5_context context,
427 	     const krb5_data *send_data,
428 	     krb5_krbhst_handle handle,
429 	     krb5_data *receive)
430 {
431      krb5_error_code ret;
432      krb5_socket_t fd;
433      size_t i;
434 
435      krb5_data_zero(receive);
436 
437      for (i = 0; i < context->max_retries; ++i) {
438 	 krb5_krbhst_info *hi;
439 
440 	 while (krb5_krbhst_next(context, handle, &hi) == 0) {
441 	     struct addrinfo *ai, *a;
442 
443 	     _krb5_debug(context, 2,
444 			 "trying to communicate with host %s in realm %s",
445 			 hi->hostname, _krb5_krbhst_get_realm(handle));
446 
447 	     if (context->send_to_kdc) {
448 		 struct send_to_kdc *s = context->send_to_kdc;
449 
450 		 ret = (*s->func)(context, s->data, hi,
451 				  context->kdc_timeout, send_data, receive);
452 		 if (ret == 0 && receive->length != 0)
453 		     goto out;
454 		 continue;
455 	     }
456 
457 	     ret = send_via_plugin(context, hi, context->kdc_timeout,
458 				   send_data, receive);
459 	     if (ret == 0 && receive->length != 0)
460 		 goto out;
461 	     else if (ret != KRB5_PLUGIN_NO_HANDLE)
462 		 continue;
463 
464 	     if(hi->proto == KRB5_KRBHST_HTTP && context->http_proxy) {
465 		 if (send_via_proxy (context, hi, send_data, receive) == 0) {
466 		     ret = 0;
467 		     goto out;
468 		 }
469 		 continue;
470 	     }
471 
472 	     ret = krb5_krbhst_get_addrinfo(context, hi, &ai);
473 	     if (ret)
474 		 continue;
475 
476 	     for (a = ai; a != NULL; a = a->ai_next) {
477 		 fd = socket (a->ai_family, a->ai_socktype | SOCK_CLOEXEC, a->ai_protocol);
478 		 if (rk_IS_BAD_SOCKET(fd))
479 		     continue;
480 		 rk_cloexec(fd);
481 		 if (timed_connect (fd, a, context->kdc_timeout) < 0) {
482 		     rk_closesocket (fd);
483 		     continue;
484 		 }
485 		 switch (hi->proto) {
486 		 case KRB5_KRBHST_HTTP :
487 		     ret = send_and_recv_http(fd, context->kdc_timeout,
488 					      "", send_data, receive);
489 		     break;
490 		 case KRB5_KRBHST_TCP :
491 		     ret = send_and_recv_tcp (fd, context->kdc_timeout,
492 					      send_data, receive);
493 		     break;
494 		 case KRB5_KRBHST_UDP :
495 		     ret = send_and_recv_udp (fd, context->kdc_timeout,
496 					      send_data, receive);
497 		     break;
498 		 }
499 		 rk_closesocket (fd);
500 		 if(ret == 0 && receive->length != 0)
501 		     goto out;
502 	     }
503 	 }
504 	 krb5_krbhst_reset(context, handle);
505      }
506      krb5_clear_error_message (context);
507      ret = KRB5_KDC_UNREACH;
508 out:
509      _krb5_debug(context, 2,
510 		 "result of trying to talk to realm %s = %d",
511 		 _krb5_krbhst_get_realm(handle), ret);
512      return ret;
513 }
514 
515 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_sendto_kdc(krb5_context context,const krb5_data * send_data,const krb5_realm * realm,krb5_data * receive)516 krb5_sendto_kdc(krb5_context context,
517 		const krb5_data *send_data,
518 		const krb5_realm *realm,
519 		krb5_data *receive)
520 {
521     return krb5_sendto_kdc_flags(context, send_data, realm, receive, 0);
522 }
523 
524 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_sendto_kdc_flags(krb5_context context,const krb5_data * send_data,const krb5_realm * realm,krb5_data * receive,int flags)525 krb5_sendto_kdc_flags(krb5_context context,
526 		      const krb5_data *send_data,
527 		      const krb5_realm *realm,
528 		      krb5_data *receive,
529 		      int flags)
530 {
531     krb5_error_code ret;
532     krb5_sendto_ctx ctx;
533 
534     ret = krb5_sendto_ctx_alloc(context, &ctx);
535     if (ret)
536 	return ret;
537     krb5_sendto_ctx_add_flags(ctx, flags);
538     krb5_sendto_ctx_set_func(ctx, _krb5_kdc_retry, NULL);
539 
540     ret = krb5_sendto_context(context, ctx, send_data, *realm, receive);
541     krb5_sendto_ctx_free(context, ctx);
542     return ret;
543 }
544 
545 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_set_send_to_kdc_func(krb5_context context,krb5_send_to_kdc_func func,void * data)546 krb5_set_send_to_kdc_func(krb5_context context,
547 			  krb5_send_to_kdc_func func,
548 			  void *data)
549 {
550     free(context->send_to_kdc);
551     if (func == NULL) {
552 	context->send_to_kdc = NULL;
553 	return 0;
554     }
555 
556     context->send_to_kdc = malloc(sizeof(*context->send_to_kdc));
557     if (context->send_to_kdc == NULL) {
558 	krb5_set_error_message(context, ENOMEM,
559 			       N_("malloc: out of memory", ""));
560 	return ENOMEM;
561     }
562 
563     context->send_to_kdc->func = func;
564     context->send_to_kdc->data = data;
565     return 0;
566 }
567 
568 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
_krb5_copy_send_to_kdc_func(krb5_context context,krb5_context to)569 _krb5_copy_send_to_kdc_func(krb5_context context, krb5_context to)
570 {
571     if (context->send_to_kdc)
572 	return krb5_set_send_to_kdc_func(to,
573 					 context->send_to_kdc->func,
574 					 context->send_to_kdc->data);
575     else
576 	return krb5_set_send_to_kdc_func(to, NULL, NULL);
577 }
578 
579 
580 
581 struct krb5_sendto_ctx_data {
582     int flags;
583     int type;
584     krb5_sendto_ctx_func func;
585     void *data;
586 };
587 
588 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_sendto_ctx_alloc(krb5_context context,krb5_sendto_ctx * ctx)589 krb5_sendto_ctx_alloc(krb5_context context, krb5_sendto_ctx *ctx)
590 {
591     *ctx = calloc(1, sizeof(**ctx));
592     if (*ctx == NULL) {
593 	krb5_set_error_message(context, ENOMEM,
594 			       N_("malloc: out of memory", ""));
595 	return ENOMEM;
596     }
597     return 0;
598 }
599 
600 KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_sendto_ctx_add_flags(krb5_sendto_ctx ctx,int flags)601 krb5_sendto_ctx_add_flags(krb5_sendto_ctx ctx, int flags)
602 {
603     ctx->flags |= flags;
604 }
605 
606 KRB5_LIB_FUNCTION int KRB5_LIB_CALL
krb5_sendto_ctx_get_flags(krb5_sendto_ctx ctx)607 krb5_sendto_ctx_get_flags(krb5_sendto_ctx ctx)
608 {
609     return ctx->flags;
610 }
611 
612 KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_sendto_ctx_set_type(krb5_sendto_ctx ctx,int type)613 krb5_sendto_ctx_set_type(krb5_sendto_ctx ctx, int type)
614 {
615     ctx->type = type;
616 }
617 
618 
619 KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_sendto_ctx_set_func(krb5_sendto_ctx ctx,krb5_sendto_ctx_func func,void * data)620 krb5_sendto_ctx_set_func(krb5_sendto_ctx ctx,
621 			 krb5_sendto_ctx_func func,
622 			 void *data)
623 {
624     ctx->func = func;
625     ctx->data = data;
626 }
627 
628 KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_sendto_ctx_free(krb5_context context,krb5_sendto_ctx ctx)629 krb5_sendto_ctx_free(krb5_context context, krb5_sendto_ctx ctx)
630 {
631     memset(ctx, 0, sizeof(*ctx));
632     free(ctx);
633 }
634 
635 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_sendto_context(krb5_context context,krb5_sendto_ctx ctx,const krb5_data * send_data,const krb5_realm realm,krb5_data * receive)636 krb5_sendto_context(krb5_context context,
637 		    krb5_sendto_ctx ctx,
638 		    const krb5_data *send_data,
639 		    const krb5_realm realm,
640 		    krb5_data *receive)
641 {
642     krb5_error_code ret;
643     krb5_krbhst_handle handle = NULL;
644     int type, freectx = 0;
645     int action;
646 
647     krb5_data_zero(receive);
648 
649     if (ctx == NULL) {
650 	freectx = 1;
651 	ret = krb5_sendto_ctx_alloc(context, &ctx);
652 	if (ret)
653 	    return ret;
654     }
655 
656     type = ctx->type;
657     if (type == 0) {
658 	if ((ctx->flags & KRB5_KRBHST_FLAGS_MASTER) || context->use_admin_kdc)
659 	    type = KRB5_KRBHST_ADMIN;
660 	else
661 	    type = KRB5_KRBHST_KDC;
662     }
663 
664     if ((int)send_data->length > context->large_msg_size)
665 	ctx->flags |= KRB5_KRBHST_FLAGS_LARGE_MSG;
666 
667     /* loop until we get back a appropriate response */
668 
669     do {
670 	action = KRB5_SENDTO_DONE;
671 
672 	krb5_data_free(receive);
673 
674 	if (handle == NULL) {
675 	    ret = krb5_krbhst_init_flags(context, realm, type,
676 					 ctx->flags, &handle);
677 	    if (ret) {
678 		if (freectx)
679 		    krb5_sendto_ctx_free(context, ctx);
680 		return ret;
681 	    }
682 	}
683 
684 	ret = krb5_sendto(context, send_data, handle, receive);
685 	if (ret)
686 	    break;
687 	if (ctx->func) {
688 	    ret = (*ctx->func)(context, ctx, ctx->data, receive, &action);
689 	    if (ret)
690 		break;
691 	}
692 	if (action != KRB5_SENDTO_CONTINUE) {
693 	    krb5_krbhst_free(context, handle);
694 	    handle = NULL;
695 	}
696     } while (action != KRB5_SENDTO_DONE);
697     if (handle)
698 	krb5_krbhst_free(context, handle);
699     if (ret == KRB5_KDC_UNREACH)
700 	krb5_set_error_message(context, ret,
701 			       N_("unable to reach any KDC in realm %s", ""),
702 			       realm);
703     if (ret)
704 	krb5_data_free(receive);
705     if (freectx)
706 	krb5_sendto_ctx_free(context, ctx);
707     return ret;
708 }
709 
710 krb5_error_code KRB5_CALLCONV
_krb5_kdc_retry(krb5_context context,krb5_sendto_ctx ctx,void * data,const krb5_data * reply,int * action)711 _krb5_kdc_retry(krb5_context context, krb5_sendto_ctx ctx, void *data,
712 		const krb5_data *reply, int *action)
713 {
714     krb5_error_code ret;
715     KRB_ERROR error;
716 
717     if(krb5_rd_error(context, reply, &error))
718 	return 0;
719 
720     ret = krb5_error_from_rd_error(context, &error, NULL);
721     krb5_free_error_contents(context, &error);
722 
723     switch(ret) {
724     case KRB5KRB_ERR_RESPONSE_TOO_BIG: {
725 	if (krb5_sendto_ctx_get_flags(ctx) & KRB5_KRBHST_FLAGS_LARGE_MSG)
726 	    break;
727 	krb5_sendto_ctx_add_flags(ctx, KRB5_KRBHST_FLAGS_LARGE_MSG);
728 	*action = KRB5_SENDTO_RESTART;
729 	break;
730     }
731     case KRB5KDC_ERR_SVC_UNAVAILABLE:
732 	*action = KRB5_SENDTO_CONTINUE;
733 	break;
734     }
735     return 0;
736 }
737