curl_gethostname.c 3.2 KB

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  1. /***************************************************************************
  2. * _ _ ____ _
  3. * Project ___| | | | _ \| |
  4. * / __| | | | |_) | |
  5. * | (__| |_| | _ <| |___
  6. * \___|\___/|_| \_\_____|
  7. *
  8. * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
  9. *
  10. * This software is licensed as described in the file COPYING, which
  11. * you should have received as part of this distribution. The terms
  12. * are also available at https://curl.se/docs/copyright.html.
  13. *
  14. * You may opt to use, copy, modify, merge, publish, distribute and/or sell
  15. * copies of the Software, and permit persons to whom the Software is
  16. * furnished to do so, under the terms of the COPYING file.
  17. *
  18. * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  19. * KIND, either express or implied.
  20. *
  21. * SPDX-License-Identifier: curl
  22. *
  23. ***************************************************************************/
  24. #include "curl_setup.h"
  25. #include "curl_gethostname.h"
  26. /*
  27. * Curl_gethostname() is a wrapper around gethostname() which allows
  28. * overriding the host name that the function would normally return.
  29. * This capability is used by the test suite to verify exact matching
  30. * of NTLM authentication, which exercises libcurl's MD4 and DES code
  31. * as well as by the SMTP module when a hostname is not provided.
  32. *
  33. * For libcurl debug enabled builds host name overriding takes place
  34. * when environment variable CURL_GETHOSTNAME is set, using the value
  35. * held by the variable to override returned host name.
  36. *
  37. * Note: The function always returns the un-qualified hostname rather
  38. * than being provider dependent.
  39. *
  40. * For libcurl shared library release builds the test suite preloads
  41. * another shared library named libhostname using the LD_PRELOAD
  42. * mechanism which intercepts, and might override, the gethostname()
  43. * function call. In this case a given platform must support the
  44. * LD_PRELOAD mechanism and additionally have environment variable
  45. * CURL_GETHOSTNAME set in order to override the returned host name.
  46. *
  47. * For libcurl static library release builds no overriding takes place.
  48. */
  49. int Curl_gethostname(char * const name, GETHOSTNAME_TYPE_ARG2 namelen)
  50. {
  51. #ifndef HAVE_GETHOSTNAME
  52. /* Allow compilation and return failure when unavailable */
  53. (void) name;
  54. (void) namelen;
  55. return -1;
  56. #else
  57. int err;
  58. char *dot;
  59. #ifdef DEBUGBUILD
  60. /* Override host name when environment variable CURL_GETHOSTNAME is set */
  61. const char *force_hostname = getenv("CURL_GETHOSTNAME");
  62. if(force_hostname) {
  63. strncpy(name, force_hostname, namelen - 1);
  64. err = 0;
  65. }
  66. else {
  67. name[0] = '\0';
  68. err = gethostname(name, namelen);
  69. }
  70. #else /* DEBUGBUILD */
  71. /* The call to system's gethostname() might get intercepted by the
  72. libhostname library when libcurl is built as a non-debug shared
  73. library when running the test suite. */
  74. name[0] = '\0';
  75. err = gethostname(name, namelen);
  76. #endif
  77. name[namelen - 1] = '\0';
  78. if(err)
  79. return err;
  80. /* Truncate domain, leave only machine name */
  81. dot = strchr(name, '.');
  82. if(dot)
  83. *dot = '\0';
  84. return 0;
  85. #endif
  86. }