libpcap  1.10.1
About: libpcap is a packet filter library used by tools like tcpdump.
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fmtutils.c
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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-int.h"
51 
52 #include "portability.h"
53 
54 #include "fmtutils.h"
55 
56 #ifdef _WIN32
57 #include "charconv.h"
58 #endif
59 
60 /*
61  * Set the encoding.
62  */
63 #ifdef _WIN32
64 /*
65  * True if we shouold use UTF-8.
66  */
67 static int use_utf_8;
68 
69 void
70 pcap_fmt_set_encoding(unsigned int opts)
71 {
72  if (opts == PCAP_CHAR_ENC_UTF_8)
73  use_utf_8 = 1;
74 }
75 #else
76 void
77 pcap_fmt_set_encoding(unsigned int opts _U_)
78 {
79  /*
80  * Nothing to do here.
81  */
82 }
83 #endif
84 
85 #ifdef _WIN32
86 /*
87  * Convert a null-terminated UTF-16LE string to UTF-8, putting it into
88  * a buffer starting at the specified location and stopping if we go
89  * past the specified size. This will only put out complete UTF-8
90  * sequences.
91  *
92  * We do this ourselves because Microsoft doesn't offer a "convert and
93  * stop at a UTF-8 character boundary if we run out of space" routine.
94  */
95 #define IS_LEADING_SURROGATE(c) \
96  ((c) >= 0xd800 && (c) < 0xdc00)
97 #define IS_TRAILING_SURROGATE(c) \
98  ((c) >= 0xdc00 && (c) < 0xe000)
99 #define SURROGATE_VALUE(leading, trailing) \
100  (((((leading) - 0xd800) << 10) | ((trailing) - 0xdc00)) + 0x10000)
101 #define REPLACEMENT_CHARACTER 0x0FFFD
102 
103 static char *
104 utf_16le_to_utf_8_truncated(const wchar_t *utf_16, char *utf_8,
105  size_t utf_8_len)
106 {
107  wchar_t c, c2;
108  uint32_t uc;
109 
110  if (utf_8_len == 0) {
111  /*
112  * Not even enough room for a trailing '\0'.
113  * Don't put anything into the buffer.
114  */
115  return (utf_8);
116  }
117 
118  while ((c = *utf_16++) != '\0') {
119  if (IS_LEADING_SURROGATE(c)) {
120  /*
121  * Leading surrogate. Must be followed by
122  * a trailing surrogate.
123  */
124  c2 = *utf_16;
125  if (c2 == '\0') {
126  /*
127  * Oops, string ends with a lead
128  * surrogate. Try to drop in
129  * a REPLACEMENT CHARACTER, and
130  * don't move the string pointer,
131  * so on the next trip through
132  * the loop we grab the terminating
133  * '\0' and quit.
134  */
135  uc = REPLACEMENT_CHARACTER;
136  } else {
137  /*
138  * OK, we can consume this 2-octet
139  * value.
140  */
141  utf_16++;
142  if (IS_TRAILING_SURROGATE(c2)) {
143  /*
144  * Trailing surrogate.
145  * This calculation will,
146  * for c being a leading
147  * surrogate and c2 being
148  * a trailing surrogate,
149  * produce a value between
150  * 0x100000 and 0x10ffff,
151  * so it's always going to be
152  * a valid Unicode code point.
153  */
154  uc = SURROGATE_VALUE(c, c2);
155  } else {
156  /*
157  * Not a trailing surroage;
158  * try to drop in a
159  * REPLACEMENT CHARACTER.
160  */
161  uc = REPLACEMENT_CHARACTER;
162  }
163  }
164  } else {
165  /*
166  * Not a leading surrogate.
167  */
168  if (IS_TRAILING_SURROGATE(c)) {
169  /*
170  * Trailing surrogate without
171  * a preceding leading surrogate.
172  * Try to drop in a REPLACEMENT
173  * CHARACTER.
174  */
175  uc = REPLACEMENT_CHARACTER;
176  } else {
177  /*
178  * This is a valid BMP character;
179  * drop it in.
180  */
181  uc = c;
182  }
183  }
184 
185  /*
186  * OK, uc is a valid Unicode character; how
187  * many bytes worth of UTF-8 does it require?
188  */
189  if (uc < 0x0080) {
190  /* 1 byte. */
191  if (utf_8_len < 2) {
192  /*
193  * Not enough room for that byte
194  * plus a trailing '\0'.
195  */
196  break;
197  }
198  *utf_8++ = (char)uc;
199  utf_8_len--;
200  } else if (uc < 0x0800) {
201  /* 2 bytes. */
202  if (utf_8_len < 3) {
203  /*
204  * Not enough room for those bytes
205  * plus a trailing '\0'.
206  */
207  break;
208  }
209  *utf_8++ = ((uc >> 6) & 0x3F) | 0xC0;
210  *utf_8++ = ((uc >> 0) & 0x3F) | 0x80;
211  utf_8_len -= 2;
212  } else if (uc < 0x010000) {
213  /* 3 bytes. */
214  if (utf_8_len < 4) {
215  /*
216  * Not enough room for those bytes
217  * plus a trailing '\0'.
218  */
219  break;
220  }
221  *utf_8++ = ((uc >> 12) & 0x0F) | 0xE0;
222  *utf_8++ = ((uc >> 6) & 0x3F) | 0x80;
223  *utf_8++ = ((uc >> 0) & 0x3F) | 0x80;
224  utf_8_len -= 3;
225  } else {
226  /* 4 bytes. */
227  if (utf_8_len < 5) {
228  /*
229  * Not enough room for those bytes
230  * plus a trailing '\0'.
231  */
232  break;
233  }
234  *utf_8++ = ((uc >> 18) & 0x03) | 0xF0;
235  *utf_8++ = ((uc >> 12) & 0x3F) | 0x80;
236  *utf_8++ = ((uc >> 6) & 0x3F) | 0x80;
237  *utf_8++ = ((uc >> 0) & 0x3F) | 0x80;
238  utf_8_len -= 3;
239  }
240  }
241 
242  /*
243  * OK, we have enough room for (at least) a trailing '\0'.
244  * (We started out with enough room, thanks to the test
245  * for a zero-length buffer at the beginning, and if
246  * there wasn't enough room for any character we wanted
247  * to put into the buffer *plus* a trailing '\0',
248  * we'd have quit before putting it into the buffer,
249  * and thus would have left enough room for the trailing
250  * '\0'.)
251  *
252  * Drop it in.
253  */
254  *utf_8 = '\0';
255 
256  /*
257  * Return a pointer to the terminating '\0', in case we
258  * want to drop something in after that.
259  */
260  return (utf_8);
261 }
262 #endif /* _WIN32 */
263 
264 /*
265  * Generate an error message based on a format, arguments, and an
266  * errno, with a message for the errno after the formatted output.
267  */
268 void
269 pcap_fmt_errmsg_for_errno(char *errbuf, size_t errbuflen, int errnum,
270  const char *fmt, ...)
271 {
272  va_list ap;
273  size_t msglen;
274  char *p;
275  size_t errbuflen_remaining;
276 
277  va_start(ap, fmt);
278  vsnprintf(errbuf, errbuflen, fmt, ap);
279  va_end(ap);
280  msglen = strlen(errbuf);
281 
282  /*
283  * Do we have enough space to append ": "?
284  * Including the terminating '\0', that's 3 bytes.
285  */
286  if (msglen + 3 > errbuflen) {
287  /* No - just give them what we've produced. */
288  return;
289  }
290  p = errbuf + msglen;
291  errbuflen_remaining = errbuflen - msglen;
292  *p++ = ':';
293  *p++ = ' ';
294  *p = '\0';
295  errbuflen_remaining -= 2;
296 
297  /*
298  * Now append the string for the error code.
299  */
300 #if defined(HAVE__WCSERROR_S)
301  /*
302  * We have a Windows-style _wcserror_s().
303  * Generate a UTF-16LE error message.
304  */
305  wchar_t utf_16_errbuf[PCAP_ERRBUF_SIZE];
306  errno_t err = _wcserror_s(utf_16_errbuf, PCAP_ERRBUF_SIZE, errnum);
307  if (err != 0) {
308  /*
309  * It doesn't appear to be documented anywhere obvious
310  * what the error returns from _wcserror_s().
311  */
312  snprintf(p, errbuflen_remaining, "Error %d", errnum);
313  return;
314  }
315 
316  /*
317  * Now convert it from UTF-16LE to UTF-8, dropping it in the
318  * remaining space in the buffer, and truncating it - cleanly,
319  * on a UTF-8 character boundary - if it doesn't fit.
320  */
321  utf_16le_to_utf_8_truncated(utf_16_errbuf, p, errbuflen_remaining);
322 
323  /*
324  * Now, if we're not in UTF-8 mode, convert errbuf to the
325  * local code page.
326  */
327  if (!use_utf_8)
328  utf_8_to_acp_truncated(errbuf);
329 #elif defined(HAVE_GNU_STRERROR_R)
330  /*
331  * We have a GNU-style strerror_r(), which is *not* guaranteed to
332  * do anything to the buffer handed to it, and which returns a
333  * pointer to the error string, which may or may not be in
334  * the buffer.
335  *
336  * It is, however, guaranteed to succeed.
337  */
338  char strerror_buf[PCAP_ERRBUF_SIZE];
339  char *errstring = strerror_r(errnum, strerror_buf, PCAP_ERRBUF_SIZE);
340  snprintf(p, errbuflen_remaining, "%s", errstring);
341 #elif defined(HAVE_POSIX_STRERROR_R)
342  /*
343  * We have a POSIX-style strerror_r(), which is guaranteed to fill
344  * in the buffer, but is not guaranteed to succeed.
345  */
346  int err = strerror_r(errnum, p, errbuflen_remaining);
347  if (err == EINVAL) {
348  /*
349  * UNIX 03 says this isn't guaranteed to produce a
350  * fallback error message.
351  */
352  snprintf(p, errbuflen_remaining, "Unknown error: %d",
353  errnum);
354  } else if (err == ERANGE) {
355  /*
356  * UNIX 03 says this isn't guaranteed to produce a
357  * fallback error message.
358  */
359  snprintf(p, errbuflen_remaining,
360  "Message for error %d is too long", errnum);
361  }
362 #else
363  /*
364  * We have neither _wcserror_s() nor strerror_r(), so we're
365  * stuck with using pcap_strerror().
366  */
367  snprintf(p, errbuflen_remaining, "%s", pcap_strerror(errnum));
368 #endif
369 }
370 
371 #ifdef _WIN32
372 /*
373  * Generate an error message based on a format, arguments, and a
374  * Win32 error, with a message for the Win32 error after the formatted output.
375  */
376 void
377 pcap_fmt_errmsg_for_win32_err(char *errbuf, size_t errbuflen, DWORD errnum,
378  const char *fmt, ...)
379 {
380  va_list ap;
381  size_t msglen;
382  char *p;
383  size_t errbuflen_remaining;
384  DWORD retval;
385  wchar_t utf_16_errbuf[PCAP_ERRBUF_SIZE];
386  size_t utf_8_len;
387 
388  va_start(ap, fmt);
389  vsnprintf(errbuf, errbuflen, fmt, ap);
390  va_end(ap);
391  msglen = strlen(errbuf);
392 
393  /*
394  * Do we have enough space to append ": "?
395  * Including the terminating '\0', that's 3 bytes.
396  */
397  if (msglen + 3 > errbuflen) {
398  /* No - just give them what we've produced. */
399  return;
400  }
401  p = errbuf + msglen;
402  errbuflen_remaining = errbuflen - msglen;
403  *p++ = ':';
404  *p++ = ' ';
405  *p = '\0';
406  msglen += 2;
407  errbuflen_remaining -= 2;
408 
409  /*
410  * Now append the string for the error code.
411  *
412  * XXX - what language ID to use?
413  *
414  * For UN*Xes, pcap_strerror() may or may not return localized
415  * strings.
416  *
417  * We currently don't have localized messages for libpcap, but
418  * we might want to do so. On the other hand, if most of these
419  * messages are going to be read by libpcap developers and
420  * perhaps by developers of libpcap-based applications, English
421  * might be a better choice, so the developer doesn't have to
422  * get the message translated if it's in a language they don't
423  * happen to understand.
424  */
425  retval = FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS|FORMAT_MESSAGE_MAX_WIDTH_MASK,
426  NULL, errnum, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
427  utf_16_errbuf, PCAP_ERRBUF_SIZE, NULL);
428  if (retval == 0) {
429  /*
430  * Failed.
431  */
432  snprintf(p, errbuflen_remaining,
433  "Couldn't get error message for error (%lu)", errnum);
434  return;
435  }
436 
437  /*
438  * Now convert it from UTF-16LE to UTF-8.
439  */
440  p = utf_16le_to_utf_8_truncated(utf_16_errbuf, p, errbuflen_remaining);
441 
442  /*
443  * Now append the error number, if it fits.
444  */
445  utf_8_len = p - errbuf;
446  errbuflen_remaining -= utf_8_len;
447  if (utf_8_len == 0) {
448  /* The message was empty. */
449  snprintf(p, errbuflen_remaining, "(%lu)", errnum);
450  } else
451  snprintf(p, errbuflen_remaining, " (%lu)", errnum);
452 
453  /*
454  * Now, if we're not in UTF-8 mode, convert errbuf to the
455  * local code page.
456  */
457  if (!use_utf_8)
458  utf_8_to_acp_truncated(errbuf);
459 }
460 #endif
void pcap_fmt_errmsg_for_errno(char *errbuf, size_t errbuflen, int errnum, const char *fmt,...)
Definition: fmtutils.c:269
void pcap_fmt_set_encoding(unsigned int opts)
Definition: fmtutils.c:77
int vsnprintf(char *, size_t, const char *, va_list)
int snprintf(char *, size_t, const char *,...)
#define _U_
Definition: pcap-dos.h:93
unsigned long DWORD
Definition: pcap-dos.h:18
#define PCAP_CHAR_ENC_UTF_8
Definition: pcap.h:383
#define PCAP_ERRBUF_SIZE
Definition: pcap.h:152
const char * pcap_strerror(int errnum)
Definition: pcap.c:3669