curl/lib/curl_gethostname.c

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2010, 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 http://curl.haxx.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.
*
***************************************************************************/
#include "setup.h"
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include "curl_gethostname.h"
/*
* Curl_gethostname() is a wrapper around gethostname() which allows
* overriding the host name that the function would normally return.
* This capability is used by the test suite to verify exact matching
* of NTLM authentication, which exercises libcurl's MD4 and DES code
* as well as by the SMTP module when a hostname is not provided.
*
* For libcurl debug enabled builds host name overriding takes place
* when environment variable CURL_GETHOSTNAME is set, using the value
* held by the variable to override returned host name.
*
* Note: The function always returns the un-qualified hostname rather
* than being provider dependent.
*
* For libcurl shared library release builds the test suite preloads
* another shared library named libhostname using the LD_PRELOAD
* mechanism which intercepts, and might override, the gethostname()
* function call. In this case a given platform must support the
* LD_PRELOAD mechanism and additionally have environment variable
* CURL_GETHOSTNAME set in order to override the returned host name.
*
* For libcurl static library release builds no overriding takes place.
*/
int Curl_gethostname(char *name, GETHOSTNAME_TYPE_ARG2 namelen) {
#ifndef HAVE_GETHOSTNAME
/* Allow compilation and return failure when unavailable */
(void) name;
(void) namelen;
return -1;
#else
int err;
char* dot;
#ifdef DEBUGBUILD
/* Override host name when environment variable CURL_GETHOSTNAME is set */
const char *force_hostname = getenv("CURL_GETHOSTNAME");
if(force_hostname) {
strncpy(name, force_hostname, namelen);
err = 0;
}
else {
name[0] = '\0';
err = gethostname(name, namelen);
}
#else /* DEBUGBUILD */
/* The call to system's gethostname() might get intercepted by the
libhostname library when libcurl is built as a non-debug shared
library when running the test suite. */
name[0] = '\0';
err = gethostname(name, namelen);
#endif
name[namelen - 1] = '\0';
if(err)
return err;
/* Truncate domain, leave only machine name */
dot = strchr(name, '.');
if(dot)
*dot = '\0';
return 0;
#endif
}