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
25 #include "curl_setup.h"
26
27 #include "curl_gethostname.h"
28
29 /*
30 * Curl_gethostname() is a wrapper around gethostname() which allows
31 * overriding the host name that the function would normally return.
32 * This capability is used by the test suite to verify exact matching
33 * of NTLM authentication, which exercises libcurl's MD4 and DES code
34 * as well as by the SMTP module when a hostname is not provided.
35 *
36 * For libcurl debug enabled builds host name overriding takes place
37 * when environment variable CURL_GETHOSTNAME is set, using the value
38 * held by the variable to override returned host name.
39 *
40 * Note: The function always returns the un-qualified hostname rather
41 * than being provider dependent.
42 *
43 * For libcurl shared library release builds the test suite preloads
44 * another shared library named libhostname using the LD_PRELOAD
45 * mechanism which intercepts, and might override, the gethostname()
46 * function call. In this case a given platform must support the
47 * LD_PRELOAD mechanism and additionally have environment variable
48 * CURL_GETHOSTNAME set in order to override the returned host name.
49 *
50 * For libcurl static library release builds no overriding takes place.
51 */
52
Curl_gethostname(char * const name,GETHOSTNAME_TYPE_ARG2 namelen)53 int Curl_gethostname(char * const name, GETHOSTNAME_TYPE_ARG2 namelen)
54 {
55 #ifndef HAVE_GETHOSTNAME
56
57 /* Allow compilation and return failure when unavailable */
58 (void) name;
59 (void) namelen;
60 return -1;
61
62 #else
63 int err;
64 char *dot;
65
66 #ifdef DEBUGBUILD
67
68 /* Override host name when environment variable CURL_GETHOSTNAME is set */
69 const char *force_hostname = getenv("CURL_GETHOSTNAME");
70 if(force_hostname) {
71 strncpy(name, force_hostname, namelen);
72 err = 0;
73 }
74 else {
75 name[0] = '\0';
76 err = gethostname(name, namelen);
77 }
78
79 #else /* DEBUGBUILD */
80
81 /* The call to system's gethostname() might get intercepted by the
82 libhostname library when libcurl is built as a non-debug shared
83 library when running the test suite. */
84 name[0] = '\0';
85 err = gethostname(name, namelen);
86
87 #endif
88
89 name[namelen - 1] = '\0';
90
91 if(err)
92 return err;
93
94 /* Truncate domain, leave only machine name */
95 dot = strchr(name, '.');
96 if(dot)
97 *dot = '\0';
98
99 return 0;
100 #endif
101
102 }
103
