xref: /third_party/curl/lib/krb5.c (revision 13498266) 
1/* GSSAPI/krb5 support for FTP - loosely based on old krb4.c
2 *
3 * Copyright (c) 1995, 1996, 1997, 1998, 1999 Kungliga Tekniska Högskolan
4 * (Royal Institute of Technology, Stockholm, Sweden).
5 * Copyright (C) Daniel Stenberg
6 * All rights reserved.
7 *
8 * SPDX-License-Identifier: BSD-3-Clause
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 *
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 *
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 *
21 * 3. Neither the name of the Institute nor the names of its contributors
22 *    may be used to endorse or promote products derived from this software
23 *    without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.  */
36
37#include "curl_setup.h"
38
39#if defined(HAVE_GSSAPI) && !defined(CURL_DISABLE_FTP)
40
41#ifdef HAVE_NETDB_H
42#include <netdb.h>
43#endif
44#ifdef HAVE_ARPA_INET_H
45#include <arpa/inet.h>
46#endif
47
48#include "urldata.h"
49#include "cfilters.h"
50#include "cf-socket.h"
51#include "curl_base64.h"
52#include "ftp.h"
53#include "curl_gssapi.h"
54#include "sendf.h"
55#include "curl_krb5.h"
56#include "warnless.h"
57#include "strcase.h"
58#include "strdup.h"
59
60/* The last 3 #include files should be in this order */
61#include "curl_printf.h"
62#include "curl_memory.h"
63#include "memdebug.h"
64
65static CURLcode ftpsend(struct Curl_easy *data, struct connectdata *conn,
66                        const char *cmd)
67{
68  ssize_t bytes_written;
69#define SBUF_SIZE 1024
70  char s[SBUF_SIZE];
71  size_t write_len;
72  char *sptr = s;
73  CURLcode result = CURLE_OK;
74#ifdef HAVE_GSSAPI
75  unsigned char data_sec = conn->data_prot;
76#endif
77
78  DEBUGASSERT(cmd);
79
80  write_len = strlen(cmd);
81  if(!write_len || write_len > (sizeof(s) -3))
82    return CURLE_BAD_FUNCTION_ARGUMENT;
83
84  memcpy(&s, cmd, write_len);
85  strcpy(&s[write_len], "\r\n"); /* append a trailing CRLF */
86  write_len += 2;
87  bytes_written = 0;
88
89  for(;;) {
90#ifdef HAVE_GSSAPI
91    conn->data_prot = PROT_CMD;
92#endif
93    result = Curl_nwrite(data, FIRSTSOCKET, sptr, write_len,
94                        &bytes_written);
95#ifdef HAVE_GSSAPI
96    DEBUGASSERT(data_sec > PROT_NONE && data_sec < PROT_LAST);
97    conn->data_prot = data_sec;
98#endif
99
100    if(result)
101      break;
102
103    Curl_debug(data, CURLINFO_HEADER_OUT, sptr, (size_t)bytes_written);
104
105    if(bytes_written != (ssize_t)write_len) {
106      write_len -= bytes_written;
107      sptr += bytes_written;
108    }
109    else
110      break;
111  }
112
113  return result;
114}
115
116static int
117krb5_init(void *app_data)
118{
119  gss_ctx_id_t *context = app_data;
120  /* Make sure our context is initialized for krb5_end. */
121  *context = GSS_C_NO_CONTEXT;
122  return 0;
123}
124
125static int
126krb5_check_prot(void *app_data, int level)
127{
128  (void)app_data; /* unused */
129  if(level == PROT_CONFIDENTIAL)
130    return -1;
131  return 0;
132}
133
134static int
135krb5_decode(void *app_data, void *buf, int len,
136            int level UNUSED_PARAM,
137            struct connectdata *conn UNUSED_PARAM)
138{
139  gss_ctx_id_t *context = app_data;
140  OM_uint32 maj, min;
141  gss_buffer_desc enc, dec;
142
143  (void)level;
144  (void)conn;
145
146  enc.value = buf;
147  enc.length = len;
148  maj = gss_unwrap(&min, *context, &enc, &dec, NULL, NULL);
149  if(maj != GSS_S_COMPLETE)
150    return -1;
151
152  memcpy(buf, dec.value, dec.length);
153  len = curlx_uztosi(dec.length);
154  gss_release_buffer(&min, &dec);
155
156  return len;
157}
158
159static int
160krb5_encode(void *app_data, const void *from, int length, int level, void **to)
161{
162  gss_ctx_id_t *context = app_data;
163  gss_buffer_desc dec, enc;
164  OM_uint32 maj, min;
165  int state;
166  int len;
167
168  /* NOTE that the cast is safe, neither of the krb5, gnu gss and heimdal
169   * libraries modify the input buffer in gss_wrap()
170   */
171  dec.value = (void *)from;
172  dec.length = length;
173  maj = gss_wrap(&min, *context,
174                 level == PROT_PRIVATE,
175                 GSS_C_QOP_DEFAULT,
176                 &dec, &state, &enc);
177
178  if(maj != GSS_S_COMPLETE)
179    return -1;
180
181  /* malloc a new buffer, in case gss_release_buffer doesn't work as
182     expected */
183  *to = malloc(enc.length);
184  if(!*to)
185    return -1;
186  memcpy(*to, enc.value, enc.length);
187  len = curlx_uztosi(enc.length);
188  gss_release_buffer(&min, &enc);
189  return len;
190}
191
192static int
193krb5_auth(void *app_data, struct Curl_easy *data, struct connectdata *conn)
194{
195  int ret = AUTH_OK;
196  char *p;
197  const char *host = conn->host.name;
198  ssize_t nread;
199  curl_socklen_t l = sizeof(conn->local_addr);
200  CURLcode result;
201  const char *service = data->set.str[STRING_SERVICE_NAME] ?
202                        data->set.str[STRING_SERVICE_NAME] :
203                        "ftp";
204  const char *srv_host = "host";
205  gss_buffer_desc input_buffer, output_buffer, _gssresp, *gssresp;
206  OM_uint32 maj, min;
207  gss_name_t gssname;
208  gss_ctx_id_t *context = app_data;
209  struct gss_channel_bindings_struct chan;
210  size_t base64_sz = 0;
211  struct sockaddr_in *remote_addr =
212    (struct sockaddr_in *)(void *)&conn->remote_addr->sa_addr;
213  char *stringp;
214
215  if(getsockname(conn->sock[FIRSTSOCKET],
216                 (struct sockaddr *)&conn->local_addr, &l) < 0)
217    perror("getsockname()");
218
219  chan.initiator_addrtype = GSS_C_AF_INET;
220  chan.initiator_address.length = l - 4;
221  chan.initiator_address.value = &conn->local_addr.sin_addr.s_addr;
222  chan.acceptor_addrtype = GSS_C_AF_INET;
223  chan.acceptor_address.length = l - 4;
224  chan.acceptor_address.value = &remote_addr->sin_addr.s_addr;
225  chan.application_data.length = 0;
226  chan.application_data.value = NULL;
227
228  /* this loop will execute twice (once for service, once for host) */
229  for(;;) {
230    /* this really shouldn't be repeated here, but can't help it */
231    if(service == srv_host) {
232      result = ftpsend(data, conn, "AUTH GSSAPI");
233      if(result)
234        return -2;
235
236      if(Curl_GetFTPResponse(data, &nread, NULL))
237        return -1;
238      else {
239        struct pingpong *pp = &conn->proto.ftpc.pp;
240        char *line = Curl_dyn_ptr(&pp->recvbuf);
241        if(line[0] != '3')
242          return -1;
243      }
244    }
245
246    stringp = aprintf("%s@%s", service, host);
247    if(!stringp)
248      return -2;
249
250    input_buffer.value = stringp;
251    input_buffer.length = strlen(stringp);
252    maj = gss_import_name(&min, &input_buffer, GSS_C_NT_HOSTBASED_SERVICE,
253                          &gssname);
254    free(stringp);
255    if(maj != GSS_S_COMPLETE) {
256      gss_release_name(&min, &gssname);
257      if(service == srv_host) {
258        failf(data, "Error importing service name %s@%s", service, host);
259        return AUTH_ERROR;
260      }
261      service = srv_host;
262      continue;
263    }
264    /* We pass NULL as |output_name_type| to avoid a leak. */
265    gss_display_name(&min, gssname, &output_buffer, NULL);
266    infof(data, "Trying against %s", (char *)output_buffer.value);
267    gssresp = GSS_C_NO_BUFFER;
268    *context = GSS_C_NO_CONTEXT;
269
270    do {
271      /* Release the buffer at each iteration to avoid leaking: the first time
272         we are releasing the memory from gss_display_name. The last item is
273         taken care by a final gss_release_buffer. */
274      gss_release_buffer(&min, &output_buffer);
275      ret = AUTH_OK;
276      maj = Curl_gss_init_sec_context(data,
277                                      &min,
278                                      context,
279                                      gssname,
280                                      &Curl_krb5_mech_oid,
281                                      &chan,
282                                      gssresp,
283                                      &output_buffer,
284                                      TRUE,
285                                      NULL);
286
287      if(gssresp) {
288        free(_gssresp.value);
289        gssresp = NULL;
290      }
291
292      if(GSS_ERROR(maj)) {
293        infof(data, "Error creating security context");
294        ret = AUTH_ERROR;
295        break;
296      }
297
298      if(output_buffer.length) {
299        char *cmd;
300
301        result = Curl_base64_encode((char *)output_buffer.value,
302                                    output_buffer.length, &p, &base64_sz);
303        if(result) {
304          infof(data, "base64-encoding: %s", curl_easy_strerror(result));
305          ret = AUTH_ERROR;
306          break;
307        }
308
309        cmd = aprintf("ADAT %s", p);
310        if(cmd)
311          result = ftpsend(data, conn, cmd);
312        else
313          result = CURLE_OUT_OF_MEMORY;
314
315        free(p);
316        free(cmd);
317
318        if(result) {
319          ret = -2;
320          break;
321        }
322
323        if(Curl_GetFTPResponse(data, &nread, NULL)) {
324          ret = -1;
325          break;
326        }
327        else {
328          struct pingpong *pp = &conn->proto.ftpc.pp;
329          size_t len = Curl_dyn_len(&pp->recvbuf);
330          p = Curl_dyn_ptr(&pp->recvbuf);
331          if((len < 4) || (p[0] != '2' && p[0] != '3')) {
332            infof(data, "Server didn't accept auth data");
333            ret = AUTH_ERROR;
334            break;
335          }
336        }
337
338        _gssresp.value = NULL; /* make sure it is initialized */
339        p += 4; /* over '789 ' */
340        p = strstr(p, "ADAT=");
341        if(p) {
342          result = Curl_base64_decode(p + 5,
343                                      (unsigned char **)&_gssresp.value,
344                                      &_gssresp.length);
345          if(result) {
346            failf(data, "base64-decoding: %s", curl_easy_strerror(result));
347            ret = AUTH_CONTINUE;
348            break;
349          }
350        }
351
352        gssresp = &_gssresp;
353      }
354    } while(maj == GSS_S_CONTINUE_NEEDED);
355
356    gss_release_name(&min, &gssname);
357    gss_release_buffer(&min, &output_buffer);
358
359    if(gssresp)
360      free(_gssresp.value);
361
362    if(ret == AUTH_OK || service == srv_host)
363      return ret;
364
365    service = srv_host;
366  }
367  return ret;
368}
369
370static void krb5_end(void *app_data)
371{
372    OM_uint32 min;
373    gss_ctx_id_t *context = app_data;
374    if(*context != GSS_C_NO_CONTEXT) {
375      OM_uint32 maj = gss_delete_sec_context(&min, context, GSS_C_NO_BUFFER);
376      (void)maj;
377      DEBUGASSERT(maj == GSS_S_COMPLETE);
378    }
379}
380
381static const struct Curl_sec_client_mech Curl_krb5_client_mech = {
382  "GSSAPI",
383  sizeof(gss_ctx_id_t),
384  krb5_init,
385  krb5_auth,
386  krb5_end,
387  krb5_check_prot,
388
389  krb5_encode,
390  krb5_decode
391};
392
393static const struct {
394  unsigned char level;
395  const char *name;
396} level_names[] = {
397  { PROT_CLEAR, "clear" },
398  { PROT_SAFE, "safe" },
399  { PROT_CONFIDENTIAL, "confidential" },
400  { PROT_PRIVATE, "private" }
401};
402
403static unsigned char name_to_level(const char *name)
404{
405  int i;
406  for(i = 0; i < (int)sizeof(level_names)/(int)sizeof(level_names[0]); i++)
407    if(curl_strequal(name, level_names[i].name))
408      return level_names[i].level;
409  return PROT_NONE;
410}
411
412/* Convert a protocol |level| to its char representation.
413   We take an int to catch programming mistakes. */
414static char level_to_char(int level)
415{
416  switch(level) {
417  case PROT_CLEAR:
418    return 'C';
419  case PROT_SAFE:
420    return 'S';
421  case PROT_CONFIDENTIAL:
422    return 'E';
423  case PROT_PRIVATE:
424    return 'P';
425  case PROT_CMD:
426  default:
427    /* Those 2 cases should not be reached! */
428    break;
429  }
430  DEBUGASSERT(0);
431  /* Default to the most secure alternative. */
432  return 'P';
433}
434
435/* Send an FTP command defined by |message| and the optional arguments. The
436   function returns the ftp_code. If an error occurs, -1 is returned. */
437static int ftp_send_command(struct Curl_easy *data, const char *message, ...)
438  CURL_PRINTF(2, 3);
439
440static int ftp_send_command(struct Curl_easy *data, const char *message, ...)
441{
442  int ftp_code;
443  ssize_t nread = 0;
444  va_list args;
445  char print_buffer[50];
446
447  va_start(args, message);
448  mvsnprintf(print_buffer, sizeof(print_buffer), message, args);
449  va_end(args);
450
451  if(ftpsend(data, data->conn, print_buffer)) {
452    ftp_code = -1;
453  }
454  else {
455    if(Curl_GetFTPResponse(data, &nread, &ftp_code))
456      ftp_code = -1;
457  }
458
459  (void)nread; /* Unused */
460  return ftp_code;
461}
462
463/* Read |len| from the socket |fd| and store it in |to|. Return a CURLcode
464   saying whether an error occurred or CURLE_OK if |len| was read. */
465static CURLcode
466socket_read(struct Curl_easy *data, int sockindex, void *to, size_t len)
467{
468  char *to_p = to;
469  CURLcode result;
470  ssize_t nread = 0;
471
472  while(len > 0) {
473    nread = Curl_conn_recv(data, sockindex, to_p, len, &result);
474    if(nread > 0) {
475      len -= nread;
476      to_p += nread;
477    }
478    else {
479      if(result == CURLE_AGAIN)
480        continue;
481      return result;
482    }
483  }
484  return CURLE_OK;
485}
486
487
488/* Write |len| bytes from the buffer |to| to the socket |fd|. Return a
489   CURLcode saying whether an error occurred or CURLE_OK if |len| was
490   written. */
491static CURLcode
492socket_write(struct Curl_easy *data, int sockindex, const void *to,
493             size_t len)
494{
495  const char *to_p = to;
496  CURLcode result;
497  ssize_t written;
498
499  while(len > 0) {
500    written = Curl_conn_send(data, sockindex, to_p, len, &result);
501    if(written > 0) {
502      len -= written;
503      to_p += written;
504    }
505    else {
506      if(result == CURLE_AGAIN)
507        continue;
508      return result;
509    }
510  }
511  return CURLE_OK;
512}
513
514static CURLcode read_data(struct Curl_easy *data, int sockindex,
515                          struct krb5buffer *buf)
516{
517  struct connectdata *conn = data->conn;
518  int len;
519  CURLcode result;
520  int nread;
521
522  result = socket_read(data, sockindex, &len, sizeof(len));
523  if(result)
524    return result;
525
526  if(len) {
527    /* only realloc if there was a length */
528    len = ntohl(len);
529    if(len > CURL_MAX_INPUT_LENGTH)
530      len = 0;
531    else
532      buf->data = Curl_saferealloc(buf->data, len);
533  }
534  if(!len || !buf->data)
535    return CURLE_OUT_OF_MEMORY;
536
537  result = socket_read(data, sockindex, buf->data, len);
538  if(result)
539    return result;
540  nread = conn->mech->decode(conn->app_data, buf->data, len,
541                             conn->data_prot, conn);
542  if(nread < 0)
543    return CURLE_RECV_ERROR;
544  buf->size = (size_t)nread;
545  buf->index = 0;
546  return CURLE_OK;
547}
548
549static size_t
550buffer_read(struct krb5buffer *buf, void *data, size_t len)
551{
552  if(buf->size - buf->index < len)
553    len = buf->size - buf->index;
554  memcpy(data, (char *)buf->data + buf->index, len);
555  buf->index += len;
556  return len;
557}
558
559/* Matches Curl_recv signature */
560static ssize_t sec_recv(struct Curl_easy *data, int sockindex,
561                        char *buffer, size_t len, CURLcode *err)
562{
563  size_t bytes_read;
564  size_t total_read = 0;
565  struct connectdata *conn = data->conn;
566
567  *err = CURLE_OK;
568
569  /* Handle clear text response. */
570  if(conn->sec_complete == 0 || conn->data_prot == PROT_CLEAR)
571    return Curl_conn_recv(data, sockindex, buffer, len, err);
572
573  if(conn->in_buffer.eof_flag) {
574    conn->in_buffer.eof_flag = 0;
575    return 0;
576  }
577
578  bytes_read = buffer_read(&conn->in_buffer, buffer, len);
579  len -= bytes_read;
580  total_read += bytes_read;
581  buffer += bytes_read;
582
583  while(len > 0) {
584    if(read_data(data, sockindex, &conn->in_buffer))
585      return -1;
586    if(conn->in_buffer.size == 0) {
587      if(bytes_read > 0)
588        conn->in_buffer.eof_flag = 1;
589      return bytes_read;
590    }
591    bytes_read = buffer_read(&conn->in_buffer, buffer, len);
592    len -= bytes_read;
593    total_read += bytes_read;
594    buffer += bytes_read;
595  }
596  return total_read;
597}
598
599/* Send |length| bytes from |from| to the |fd| socket taking care of encoding
600   and negotiating with the server. |from| can be NULL. */
601static void do_sec_send(struct Curl_easy *data, struct connectdata *conn,
602                        curl_socket_t fd, const char *from, int length)
603{
604  int bytes, htonl_bytes; /* 32-bit integers for htonl */
605  char *buffer = NULL;
606  char *cmd_buffer;
607  size_t cmd_size = 0;
608  CURLcode error;
609  enum protection_level prot_level = conn->data_prot;
610  bool iscmd = (prot_level == PROT_CMD)?TRUE:FALSE;
611
612  DEBUGASSERT(prot_level > PROT_NONE && prot_level < PROT_LAST);
613
614  if(iscmd) {
615    if(!strncmp(from, "PASS ", 5) || !strncmp(from, "ACCT ", 5))
616      prot_level = PROT_PRIVATE;
617    else
618      prot_level = conn->command_prot;
619  }
620  bytes = conn->mech->encode(conn->app_data, from, length, prot_level,
621                             (void **)&buffer);
622  if(!buffer || bytes <= 0)
623    return; /* error */
624
625  if(iscmd) {
626    error = Curl_base64_encode(buffer, curlx_sitouz(bytes),
627                               &cmd_buffer, &cmd_size);
628    if(error) {
629      free(buffer);
630      return; /* error */
631    }
632    if(cmd_size > 0) {
633      static const char *enc = "ENC ";
634      static const char *mic = "MIC ";
635      if(prot_level == PROT_PRIVATE)
636        socket_write(data, fd, enc, 4);
637      else
638        socket_write(data, fd, mic, 4);
639
640      socket_write(data, fd, cmd_buffer, cmd_size);
641      socket_write(data, fd, "\r\n", 2);
642      infof(data, "Send: %s%s", prot_level == PROT_PRIVATE?enc:mic,
643            cmd_buffer);
644      free(cmd_buffer);
645    }
646  }
647  else {
648    htonl_bytes = htonl(bytes);
649    socket_write(data, fd, &htonl_bytes, sizeof(htonl_bytes));
650    socket_write(data, fd, buffer, curlx_sitouz(bytes));
651  }
652  free(buffer);
653}
654
655static ssize_t sec_write(struct Curl_easy *data, struct connectdata *conn,
656                         curl_socket_t fd, const char *buffer, size_t length)
657{
658  ssize_t tx = 0, len = conn->buffer_size;
659
660  if(len <= 0)
661    len = length;
662  while(length) {
663    if(length < (size_t)len)
664      len = length;
665
666    do_sec_send(data, conn, fd, buffer, curlx_sztosi(len));
667    length -= len;
668    buffer += len;
669    tx += len;
670  }
671  return tx;
672}
673
674/* Matches Curl_send signature */
675static ssize_t sec_send(struct Curl_easy *data, int sockindex,
676                        const void *buffer, size_t len, CURLcode *err)
677{
678  struct connectdata *conn = data->conn;
679  curl_socket_t fd = conn->sock[sockindex];
680  *err = CURLE_OK;
681  return sec_write(data, conn, fd, buffer, len);
682}
683
684int Curl_sec_read_msg(struct Curl_easy *data, struct connectdata *conn,
685                      char *buffer, enum protection_level level)
686{
687  /* decoded_len should be size_t or ssize_t but conn->mech->decode returns an
688     int */
689  int decoded_len;
690  char *buf;
691  int ret_code = 0;
692  size_t decoded_sz = 0;
693  CURLcode error;
694
695  (void) data;
696
697  if(!conn->mech)
698    /* not initialized, return error */
699    return -1;
700
701  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
702
703  error = Curl_base64_decode(buffer + 4, (unsigned char **)&buf, &decoded_sz);
704  if(error || decoded_sz == 0)
705    return -1;
706
707  if(decoded_sz > (size_t)INT_MAX) {
708    free(buf);
709    return -1;
710  }
711  decoded_len = curlx_uztosi(decoded_sz);
712
713  decoded_len = conn->mech->decode(conn->app_data, buf, decoded_len,
714                                   level, conn);
715  if(decoded_len <= 0) {
716    free(buf);
717    return -1;
718  }
719
720  {
721    buf[decoded_len] = '\n';
722    Curl_debug(data, CURLINFO_HEADER_IN, buf, decoded_len + 1);
723  }
724
725  buf[decoded_len] = '\0';
726  if(decoded_len <= 3)
727    /* suspiciously short */
728    return 0;
729
730  if(buf[3] != '-')
731    ret_code = atoi(buf);
732
733  if(buf[decoded_len - 1] == '\n')
734    buf[decoded_len - 1] = '\0';
735  strcpy(buffer, buf);
736  free(buf);
737  return ret_code;
738}
739
740static int sec_set_protection_level(struct Curl_easy *data)
741{
742  int code;
743  struct connectdata *conn = data->conn;
744  unsigned char level = conn->request_data_prot;
745
746  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
747
748  if(!conn->sec_complete) {
749    infof(data, "Trying to change the protection level after the"
750                " completion of the data exchange.");
751    return -1;
752  }
753
754  /* Bail out if we try to set up the same level */
755  if(conn->data_prot == level)
756    return 0;
757
758  if(level) {
759    char *pbsz;
760    unsigned int buffer_size = 1 << 20; /* 1048576 */
761    struct pingpong *pp = &conn->proto.ftpc.pp;
762    char *line;
763
764    code = ftp_send_command(data, "PBSZ %u", buffer_size);
765    if(code < 0)
766      return -1;
767
768    if(code/100 != 2) {
769      failf(data, "Failed to set the protection's buffer size.");
770      return -1;
771    }
772    conn->buffer_size = buffer_size;
773
774    line = Curl_dyn_ptr(&pp->recvbuf);
775    pbsz = strstr(line, "PBSZ=");
776    if(pbsz) {
777      /* stick to default value if the check fails */
778      if(ISDIGIT(pbsz[5]))
779        buffer_size = atoi(&pbsz[5]);
780      if(buffer_size < conn->buffer_size)
781        conn->buffer_size = buffer_size;
782    }
783  }
784
785  /* Now try to negotiate the protection level. */
786  code = ftp_send_command(data, "PROT %c", level_to_char(level));
787
788  if(code < 0)
789    return -1;
790
791  if(code/100 != 2) {
792    failf(data, "Failed to set the protection level.");
793    return -1;
794  }
795
796  conn->data_prot = level;
797  if(level == PROT_PRIVATE)
798    conn->command_prot = level;
799
800  return 0;
801}
802
803int
804Curl_sec_request_prot(struct connectdata *conn, const char *level)
805{
806  unsigned char l = name_to_level(level);
807  if(l == PROT_NONE)
808    return -1;
809  DEBUGASSERT(l > PROT_NONE && l < PROT_LAST);
810  conn->request_data_prot = l;
811  return 0;
812}
813
814static CURLcode choose_mech(struct Curl_easy *data, struct connectdata *conn)
815{
816  int ret;
817  void *tmp_allocation;
818  const struct Curl_sec_client_mech *mech = &Curl_krb5_client_mech;
819
820  tmp_allocation = realloc(conn->app_data, mech->size);
821  if(!tmp_allocation) {
822    failf(data, "Failed realloc of size %zu", mech->size);
823    mech = NULL;
824    return CURLE_OUT_OF_MEMORY;
825  }
826  conn->app_data = tmp_allocation;
827
828  if(mech->init) {
829    ret = mech->init(conn->app_data);
830    if(ret) {
831      infof(data, "Failed initialization for %s. Skipping it.",
832            mech->name);
833      return CURLE_FAILED_INIT;
834    }
835  }
836
837  infof(data, "Trying mechanism %s...", mech->name);
838  ret = ftp_send_command(data, "AUTH %s", mech->name);
839  if(ret < 0)
840    return CURLE_COULDNT_CONNECT;
841
842  if(ret/100 != 3) {
843    switch(ret) {
844    case 504:
845      infof(data, "Mechanism %s is not supported by the server (server "
846            "returned ftp code: 504).", mech->name);
847      break;
848    case 534:
849      infof(data, "Mechanism %s was rejected by the server (server returned "
850            "ftp code: 534).", mech->name);
851      break;
852    default:
853      if(ret/100 == 5) {
854        infof(data, "server does not support the security extensions");
855        return CURLE_USE_SSL_FAILED;
856      }
857      break;
858    }
859    return CURLE_LOGIN_DENIED;
860  }
861
862  /* Authenticate */
863  ret = mech->auth(conn->app_data, data, conn);
864
865  if(ret != AUTH_CONTINUE) {
866    if(ret != AUTH_OK) {
867      /* Mechanism has dumped the error to stderr, don't error here. */
868      return CURLE_USE_SSL_FAILED;
869    }
870    DEBUGASSERT(ret == AUTH_OK);
871
872    conn->mech = mech;
873    conn->sec_complete = 1;
874    conn->recv[FIRSTSOCKET] = sec_recv;
875    conn->send[FIRSTSOCKET] = sec_send;
876    conn->recv[SECONDARYSOCKET] = sec_recv;
877    conn->send[SECONDARYSOCKET] = sec_send;
878    conn->command_prot = PROT_SAFE;
879    /* Set the requested protection level */
880    /* BLOCKING */
881    (void)sec_set_protection_level(data);
882  }
883
884  return CURLE_OK;
885}
886
887CURLcode
888Curl_sec_login(struct Curl_easy *data, struct connectdata *conn)
889{
890  return choose_mech(data, conn);
891}
892
893
894void
895Curl_sec_end(struct connectdata *conn)
896{
897  if(conn->mech && conn->mech->end)
898    conn->mech->end(conn->app_data);
899  free(conn->app_data);
900  conn->app_data = NULL;
901  if(conn->in_buffer.data) {
902    free(conn->in_buffer.data);
903    conn->in_buffer.data = NULL;
904    conn->in_buffer.size = 0;
905    conn->in_buffer.index = 0;
906    conn->in_buffer.eof_flag = 0;
907  }
908  conn->sec_complete = 0;
909  conn->data_prot = PROT_CLEAR;
910  conn->mech = NULL;
911}
912
913#endif /* HAVE_GSSAPI && !CURL_DISABLE_FTP */
914