fmtutils.c

/*
 * Copyright (c) 1993, 1994, 1995, 1996, 1997, 1998
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Utilities for message formatting used both by libpcap and rpcapd.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "ftmacros.h"

#include <stddef.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <pcap/pcap.h>

#include "portability.h"

#include "fmtutils.h"

/*
 * Generate an error message based on a format, arguments, and an
 * errno, with a message for the errno after the formatted output.
 */
void
pcap_fmt_errmsg_for_errno(char *errbuf, size_t errbuflen, int errnum,
    const char *fmt, ...)
{
	va_list ap;
	size_t msglen;
	char *p;
	size_t errbuflen_remaining;

	va_start(ap, fmt);
	vsnprintf(errbuf, errbuflen, fmt, ap);
	va_end(ap);
	msglen = strlen(errbuf);

	/*
	 * Do we have enough space to append ": "?
	 * Including the terminating '\0', that's 3 bytes.
	 */
	if (msglen + 3 > errbuflen) {
		/* No - just give them what we've produced. */
		return;
	}
	p = errbuf + msglen;
	errbuflen_remaining = errbuflen - msglen;
	*p++ = ':';
	*p++ = ' ';
	*p = '\0';
	msglen += 2;
	errbuflen_remaining -= 2;

	/*
	 * Now append the string for the error code.
	 */
#if defined(HAVE_STRERROR_S)
	/*
	 * We have a Windows-style strerror_s().
	 */
	errno_t err = strerror_s(p, errbuflen_remaining, errnum);
	if (err != 0) {
		/*
		 * It doesn't appear to be documented anywhere obvious
		 * what the error returns from strerror_s().
		 */
		snprintf(p, errbuflen_remaining, "Error %d", errnum);
	}
#elif defined(HAVE_GNU_STRERROR_R)
	/*
	 * We have a GNU-style strerror_r(), which is *not* guaranteed to
	 * do anything to the buffer handed to it, and which returns a
	 * pointer to the error string, which may or may not be in
	 * the buffer.
	 *
	 * It is, however, guaranteed to succeed.
	 */
	char strerror_buf[PCAP_ERRBUF_SIZE];
	char *errstring = strerror_r(errnum, strerror_buf, PCAP_ERRBUF_SIZE);
	snprintf(p, errbuflen_remaining, "%s", errstring);
#elif defined(HAVE_POSIX_STRERROR_R)
	/*
	 * We have a POSIX-style strerror_r(), which is guaranteed to fill
	 * in the buffer, but is not guaranteed to succeed.
	 */
	int err = strerror_r(errnum, p, errbuflen_remaining);
	if (err == EINVAL) {
		/*
		 * UNIX 03 says this isn't guaranteed to produce a
		 * fallback error message.
		 */
		snprintf(p, errbuflen_remaining, "Unknown error: %d",
		    errnum);
	} else if (err == ERANGE) {
		/*
		 * UNIX 03 says this isn't guaranteed to produce a
		 * fallback error message.
		 */
		snprintf(p, errbuflen_remaining,
		    "Message for error %d is too long", errnum);
	}
#else
	/*
	 * We have neither strerror_s() nor strerror_r(), so we're
	 * stuck with using pcap_strerror().
	 */
	snprintf(p, errbuflen_remaining, "%s", pcap_strerror(errnum));
#endif
}

#ifdef _WIN32
/*
 * Generate an error message based on a format, arguments, and a
 * Win32 error, with a message for the Win32 error after the formatted output.
 */
void
pcap_fmt_errmsg_for_win32_err(char *errbuf, size_t errbuflen, DWORD errnum,
    const char *fmt, ...)
{
	va_list ap;
	size_t msglen;
	char *p;
	size_t errbuflen_remaining;
	DWORD retval;
	char win32_errbuf[PCAP_ERRBUF_SIZE+1];

	va_start(ap, fmt);
	vsnprintf(errbuf, errbuflen, fmt, ap);
	va_end(ap);
	msglen = strlen(errbuf);

	/*
	 * Do we have enough space to append ": "?
	 * Including the terminating '\0', that's 3 bytes.
	 */
	if (msglen + 3 > errbuflen) {
		/* No - just give them what we've produced. */
		return;
	}
	p = errbuf + msglen;
	errbuflen_remaining = errbuflen - msglen;
	*p++ = ':';
	*p++ = ' ';
	*p = '\0';
	msglen += 2;
	errbuflen_remaining -= 2;

	/*
	 * Now append the string for the error code.
	 *
	 * XXX - what language ID to use?
	 *
	 * For UN*Xes, pcap_strerror() may or may not return localized
	 * strings.
	 *
	 * We currently don't have localized messages for libpcap, but
	 * we might want to do so.  On the other hand, if most of these
	 * messages are going to be read by libpcap developers and
	 * perhaps by developers of libpcap-based applications, English
	 * might be a better choice, so the developer doesn't have to
	 * get the message translated if it's in a language they don't
	 * happen to understand.
	 */
	retval = FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS|FORMAT_MESSAGE_MAX_WIDTH_MASK,
	    NULL, errnum, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
	    win32_errbuf, PCAP_ERRBUF_SIZE, NULL);
	if (retval == 0) {
		/*
		 * Failed.
		 */
		snprintf(p, errbuflen_remaining,
		    "Couldn't get error message for error (%lu)", errnum);
		return;
	}

	snprintf(p, errbuflen_remaining, "%s (%lu)", win32_errbuf, errnum);
}
#endif