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    1: /***************************************************************************
    2:  *                                  _   _ ____  _
    3:  *  Project                     ___| | | |  _ \| |
    4:  *                             / __| | | | |_) | |
    5:  *                            | (__| |_| |  _ <| |___
    6:  *                             \___|\___/|_| \_\_____|
    7:  *
    8:  * Copyright (C) 1998 - 2016, 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.haxx.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:  ***************************************************************************/
   22: 
   23: #include "curl_setup.h"
   24: 
   25: #include "curl_gethostname.h"
   26: 
   27: /*
   28:  * Curl_gethostname() is a wrapper around gethostname() which allows
   29:  * overriding the host name that the function would normally return.
   30:  * This capability is used by the test suite to verify exact matching
   31:  * of NTLM authentication, which exercises libcurl's MD4 and DES code
   32:  * as well as by the SMTP module when a hostname is not provided.
   33:  *
   34:  * For libcurl debug enabled builds host name overriding takes place
   35:  * when environment variable CURL_GETHOSTNAME is set, using the value
   36:  * held by the variable to override returned host name.
   37:  *
   38:  * Note: The function always returns the un-qualified hostname rather
   39:  * than being provider dependent.
   40:  *
   41:  * For libcurl shared library release builds the test suite preloads
   42:  * another shared library named libhostname using the LD_PRELOAD
   43:  * mechanism which intercepts, and might override, the gethostname()
   44:  * function call. In this case a given platform must support the
   45:  * LD_PRELOAD mechanism and additionally have environment variable
   46:  * CURL_GETHOSTNAME set in order to override the returned host name.
   47:  *
   48:  * For libcurl static library release builds no overriding takes place.
   49:  */
   50: 
   51: int Curl_gethostname(char *name, GETHOSTNAME_TYPE_ARG2 namelen)
   52: {
   53: #ifndef HAVE_GETHOSTNAME
   54: 
   55:   /* Allow compilation and return failure when unavailable */
   56:   (void) name;
   57:   (void) namelen;
   58:   return -1;
   59: 
   60: #else
   61:   int err;
   62:   char *dot;
   63: 
   64: #ifdef DEBUGBUILD
   65: 
   66:   /* Override host name when environment variable CURL_GETHOSTNAME is set */
   67:   const char *force_hostname = getenv("CURL_GETHOSTNAME");
   68:   if(force_hostname) {
   69:     strncpy(name, force_hostname, namelen);
   70:     err = 0;
   71:   }
   72:   else {
   73:     name[0] = '\0';
   74:     err = gethostname(name, namelen);
   75:   }
   76: 
   77: #else /* DEBUGBUILD */
   78: 
   79:   /* The call to system's gethostname() might get intercepted by the
   80:      libhostname library when libcurl is built as a non-debug shared
   81:      library when running the test suite. */
   82:   name[0] = '\0';
   83:   err = gethostname(name, namelen);
   84: 
   85: #endif
   86: 
   87:   name[namelen - 1] = '\0';
   88: 
   89:   if(err)
   90:     return err;
   91: 
   92:   /* Truncate domain, leave only machine name */
   93:   dot = strchr(name, '.');
   94:   if(dot)
   95:     *dot = '\0';
   96: 
   97:   return 0;
   98: #endif
   99: 
  100: }