lib/curl_path.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl AND ISC
 *
 ***************************************************************************/

#include "curl_setup.h"

#if defined(USE_SSH)

#include <curl/curl.h>
#include "curl_memory.h"
#include "curl_path.h"
#include "escape.h"
#include "memdebug.h"

#define MAX_SSHPATH_LEN 100000 /* arbitrary */

/* figure out the path to work with in this particular request */
CURLcode Curl_getworkingpath(struct Curl_easy *data,
                             char *homedir,  /* when SFTP is used */
                             char **path) /* returns the  allocated
                                             real path to work with */
{
  char *working_path;
  size_t working_path_len;
  struct dynbuf npath;
  CURLcode result =
    Curl_urldecode(data->state.up.path, 0, &working_path,
                   &working_path_len, REJECT_ZERO);
  if(result)
    return result;

  /* new path to switch to in case we need to */
  Curl_dyn_init(&npath, MAX_SSHPATH_LEN);

  /* Check for /~/, indicating relative to the user's home directory */
  if((data->conn->handler->protocol & CURLPROTO_SCP) &&
     (working_path_len > 3) && (!memcmp(working_path, "/~/", 3))) {
    /* It is referenced to the home directory, so strip the leading '/~/' */
    if(Curl_dyn_addn(&npath, &working_path[3], working_path_len - 3)) {
      free(working_path);
      return CURLE_OUT_OF_MEMORY;
    }
  }
  else if((data->conn->handler->protocol & CURLPROTO_SFTP) &&
          (!strcmp("/~", working_path) ||
           ((working_path_len > 2) && !memcmp(working_path, "/~/", 3)))) {
    if(Curl_dyn_add(&npath, homedir)) {
      free(working_path);
      return CURLE_OUT_OF_MEMORY;
    }
    if(working_path_len > 2) {
      size_t len;
      const char *p;
      int copyfrom = 3;
      /* Copy a separating '/' if homedir does not end with one */
      len = Curl_dyn_len(&npath);
      p = Curl_dyn_ptr(&npath);
      if(len && (p[len-1] != '/'))
        copyfrom = 2;

      if(Curl_dyn_addn(&npath,
                       &working_path[copyfrom], working_path_len - copyfrom)) {
        free(working_path);
        return CURLE_OUT_OF_MEMORY;
      }
    }
  }

  if(Curl_dyn_len(&npath)) {
    free(working_path);

    /* store the pointer for the caller to receive */
    *path = Curl_dyn_ptr(&npath);
  }
  else
    *path = working_path;

  return CURLE_OK;
}

/* The original get_pathname() function came from OpenSSH sftp.c version
   4.6p1. */
/*
 * Copyright (c) 2001-2004 Damien Miller <djm@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#define MAX_PATHLENGTH 65535 /* arbitrary long */

CURLcode Curl_get_pathname(const char **cpp, char **path, const char *homedir)
{
  const char *cp = *cpp, *end;
  char quot;
  unsigned int i;
  static const char WHITESPACE[] = " \t\r\n";
  struct dynbuf out;
  CURLcode result;

  DEBUGASSERT(homedir);
  *path = NULL;
  *cpp = NULL;
  if(!*cp || !homedir)
    return CURLE_QUOTE_ERROR;

  Curl_dyn_init(&out, MAX_PATHLENGTH);

  /* Ignore leading whitespace */
  cp += strspn(cp, WHITESPACE);

  /* Check for quoted filenames */
  if(*cp == '\"' || *cp == '\'') {
    quot = *cp++;

    /* Search for terminating quote, unescape some chars */
    for(i = 0; i <= strlen(cp); i++) {
      if(cp[i] == quot) {  /* Found quote */
        i++;
        break;
      }
      if(cp[i] == '\0') {  /* End of string */
        goto fail;
      }
      if(cp[i] == '\\') {  /* Escaped characters */
        i++;
        if(cp[i] != '\'' && cp[i] != '\"' &&
            cp[i] != '\\') {
          goto fail;
        }
      }
      result = Curl_dyn_addn(&out, &cp[i], 1);
      if(result)
        return result;
    }

    if(!Curl_dyn_len(&out))
      goto fail;

    /* return pointer to second parameter if it exists */
    *cpp = &cp[i] + strspn(&cp[i], WHITESPACE);
  }
  else {
    /* Read to end of filename - either to whitespace or terminator */
    end = strpbrk(cp, WHITESPACE);
    if(!end)
      end = strchr(cp, '\0');

    /* return pointer to second parameter if it exists */
    *cpp = end + strspn(end, WHITESPACE);

    /* Handling for relative path - prepend home directory */
    if(cp[0] == '/' && cp[1] == '~' && cp[2] == '/') {
      result = Curl_dyn_add(&out, homedir);
      if(!result)
        result = Curl_dyn_addn(&out, "/", 1);
      if(result)
        return result;
      cp += 3;
    }
    /* Copy path name up until first "whitespace" */
    result = Curl_dyn_addn(&out, cp, (end - cp));
    if(result)
      return result;
  }
  *path = Curl_dyn_ptr(&out);
  return CURLE_OK;

fail:
  Curl_dyn_free(&out);
  return CURLE_QUOTE_ERROR;
}

#endif /* if SSH is used */