The Tcpdump Group git mirrors - libpcap/blob - fmtutils.c

   1 /*
   2  * Copyright (c) 1993, 1994, 1995, 1996, 1997, 1998
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the Computer Systems
  16  *      Engineering Group at Lawrence Berkeley Laboratory.
  17  * 4. Neither the name of the University nor of the Laboratory may be used
  18  *    to endorse or promote products derived from this software without
  19  *    specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 /*
  35  * Utilities for message formatting used both by libpcap and rpcapd.
  36  */
  37
  38 #ifdef HAVE_CONFIG_H
  39 #include <config.h>
  40 #endif
  41
  42 #include "ftmacros.h"
  43
  44 #include <stddef.h>
  45 #include <stdarg.h>
  46 #include <stdio.h>
  47 #include <string.h>
  48 #include <errno.h>
  49
  50 #include <pcap/pcap.h>
  51
  52 #include "portability.h"
  53
  54 #include "fmtutils.h"
  55
  56 /*
  57  * Generate an error message based on a format, arguments, and an
  58  * errno, with a message for the errno after the formatted output.
  59  */
  60 void
  61 pcap_fmt_errmsg_for_errno(char *errbuf, size_t errbuflen, int errnum,
  62     const char *fmt, ...)
  63 {
  64         va_list ap;
  65         size_t msglen;
  66         char *p;
  67         size_t errbuflen_remaining;
  68
  69         va_start(ap, fmt);
  70         vsnprintf(errbuf, errbuflen, fmt, ap);
  71         va_end(ap);
  72         msglen = strlen(errbuf);
  73
  74         /*
  75          * Do we have enough space to append ": "?
  76          * Including the terminating '\0', that's 3 bytes.
  77          */
  78         if (msglen + 3 > errbuflen) {
  79                 /* No - just give them what we've produced. */
  80                 return;
  81         }
  82         p = errbuf + msglen;
  83         errbuflen_remaining = errbuflen - msglen;
  84         *p++ = ':';
  85         *p++ = ' ';
  86         *p = '\0';
  87         errbuflen_remaining -= 2;
  88
  89         /*
  90          * Now append the string for the error code.
  91          */
  92 #if defined(HAVE_STRERROR_S)
  93         /*
  94          * We have a Windows-style strerror_s().
  95          */
  96         errno_t err = strerror_s(p, errbuflen_remaining, errnum);
  97         if (err != 0) {
  98                 /*
  99                  * It doesn't appear to be documented anywhere obvious
 100                  * what the error returns from strerror_s().
 101                  */
 102                 snprintf(p, errbuflen_remaining, "Error %d", errnum);
 103         }
 104 #elif defined(HAVE_GNU_STRERROR_R)
 105         /*
 106          * We have a GNU-style strerror_r(), which is *not* guaranteed to
 107          * do anything to the buffer handed to it, and which returns a
 108          * pointer to the error string, which may or may not be in
 109          * the buffer.
 110          *
 111          * It is, however, guaranteed to succeed.
 112          */
 113         char strerror_buf[PCAP_ERRBUF_SIZE];
 114         char *errstring = strerror_r(errnum, strerror_buf, PCAP_ERRBUF_SIZE);
 115         snprintf(p, errbuflen_remaining, "%s", errstring);
 116 #elif defined(HAVE_POSIX_STRERROR_R)
 117         /*
 118          * We have a POSIX-style strerror_r(), which is guaranteed to fill
 119          * in the buffer, but is not guaranteed to succeed.
 120          */
 121         int err = strerror_r(errnum, p, errbuflen_remaining);
 122         if (err == EINVAL) {
 123                 /*
 124                  * UNIX 03 says this isn't guaranteed to produce a
 125                  * fallback error message.
 126                  */
 127                 snprintf(p, errbuflen_remaining, "Unknown error: %d",
 128                     errnum);
 129         } else if (err == ERANGE) {
 130                 /*
 131                  * UNIX 03 says this isn't guaranteed to produce a
 132                  * fallback error message.
 133                  */
 134                 snprintf(p, errbuflen_remaining,
 135                     "Message for error %d is too long", errnum);
 136         }
 137 #else
 138         /*
 139          * We have neither strerror_s() nor strerror_r(), so we're
 140          * stuck with using pcap_strerror().
 141          */
 142         snprintf(p, errbuflen_remaining, "%s", pcap_strerror(errnum));
 143 #endif
 144 }
 145
 146 #ifdef _WIN32
 147 /*
 148  * Generate an error message based on a format, arguments, and a
 149  * Win32 error, with a message for the Win32 error after the formatted output.
 150  */
 151 void
 152 pcap_fmt_errmsg_for_win32_err(char *errbuf, size_t errbuflen, DWORD errnum,
 153     const char *fmt, ...)
 154 {
 155         va_list ap;
 156         size_t msglen;
 157         char *p;
 158         size_t errbuflen_remaining;
 159         DWORD retval;
 160         char win32_errbuf[PCAP_ERRBUF_SIZE+1];
 161
 162         va_start(ap, fmt);
 163         vsnprintf(errbuf, errbuflen, fmt, ap);
 164         va_end(ap);
 165         msglen = strlen(errbuf);
 166
 167         /*
 168          * Do we have enough space to append ": "?
 169          * Including the terminating '\0', that's 3 bytes.
 170          */
 171         if (msglen + 3 > errbuflen) {
 172                 /* No - just give them what we've produced. */
 173                 return;
 174         }
 175         p = errbuf + msglen;
 176         errbuflen_remaining = errbuflen - msglen;
 177         *p++ = ':';
 178         *p++ = ' ';
 179         *p = '\0';
 180         msglen += 2;
 181         errbuflen_remaining -= 2;
 182
 183         /*
 184          * Now append the string for the error code.
 185          *
 186          * XXX - what language ID to use?
 187          *
 188          * For UN*Xes, pcap_strerror() may or may not return localized
 189          * strings.
 190          *
 191          * We currently don't have localized messages for libpcap, but
 192          * we might want to do so.  On the other hand, if most of these
 193          * messages are going to be read by libpcap developers and
 194          * perhaps by developers of libpcap-based applications, English
 195          * might be a better choice, so the developer doesn't have to
 196          * get the message translated if it's in a language they don't
 197          * happen to understand.
 198          */
 199         retval = FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS|FORMAT_MESSAGE_MAX_WIDTH_MASK,
 200             NULL, errnum, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 201             win32_errbuf, PCAP_ERRBUF_SIZE, NULL);
 202         if (retval == 0) {
 203                 /*
 204                  * Failed.
 205                  */
 206                 snprintf(p, errbuflen_remaining,
 207                     "Couldn't get error message for error (%lu)", errnum);
 208                 return;
 209         }
 210
 211         snprintf(p, errbuflen_remaining, "%s (%lu)", win32_errbuf, errnum);
 212 }
 213 #endif