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From Jason Masker (bug 5240): 

`
Allow editcap to chop from beginning of packet for decapsulation


svn path=/trunk/; revision=35832
This commit is contained in:
Sake Blok 2011-02-04 21:09:55 +00:00
parent 8b6e2eac3d
commit b723ee91a0
2 changed files with 22 additions and 14 deletions
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10
doc/editcap.pod
View File

@ -80,11 +80,13 @@ opened. The default is to use a single output file.
=item -C E<lt>choplenE<gt>
Sets the chop length to use when writing the packet data.
Each packet is chopped at the packet end by a few <choplen> bytes of data.
Sets the chop length to use when writing the packet data. Each packet is
chopped by a few <choplen> bytes of data. Positive values chop at the packet
beginning while negative values chop at the packet end.
This is useful in the rare case that the conversion between two file
formats leaves some random bytes at the end of each packet.
This is useful for chopping headers for decapsulation of an entire capture or
in the rare case that the conversion between two file formats leaves some random
bytes at the end of each packet.
=item -d

26
editcap.c
View File

@ -699,7 +699,9 @@ usage(gboolean is_error)
fprintf(output, "\n");
fprintf(output, "Packet manipulation:\n");
fprintf(output, " -s <snaplen> truncate each packet to max. <snaplen> bytes of data.\n");
fprintf(output, " -C <choplen> chop each packet at the end by <choplen> bytes.\n");
fprintf(output, " -C <choplen> chop each packet by <choplen> bytes. Positive values\n");
fprintf(output, " chop at the packet beginning, negative values at the\n");
fprintf(output, " packet end.\n");
fprintf(output, " -t <time adjustment> adjust the timestamp of each packet;\n");
fprintf(output, " <time adjustment> is in relative seconds (e.g. -0.5).\n");
fprintf(output, " -S <strict adjustment> adjust timestamp of packets if necessary to insure\n");
@ -823,7 +825,7 @@ main(int argc, char *argv[])
char *p;
unsigned int snaplen = 0; /* No limit */
unsigned int choplen = 0; /* No chop */
int choplen = 0; /* No chop */
wtap_dumper *pdh = NULL;
int count = 1;
unsigned duplicate_count = 0;
@ -912,7 +914,7 @@ main(int argc, char *argv[])
break;
case 'C':
choplen = strtol(optarg, &p, 10);
choplen = strtol(optarg, &p, 10);
if (p == optarg || *p != '\0') {
fprintf(stderr, "editcap: \"%s\" isn't a valid chop length\n",
optarg);
@ -1131,6 +1133,7 @@ main(int argc, char *argv[])
while (wtap_read(wth, &err, &err_info, &data_offset)) {
phdr = wtap_phdr(wth);
buf = wtap_buf_ptr(wth);
if (nstime_is_unset(&block_start)) { /* should only be the first packet */
block_start.secs = phdr->ts.secs;
@ -1228,9 +1231,17 @@ main(int argc, char *argv[])
phdr = wtap_phdr(wth);
if (choplen != 0 && phdr->caplen > choplen) {
if (choplen < 0 && (phdr->caplen + choplen) > 0) {
snap_phdr = *phdr;
snap_phdr.caplen += choplen;
phdr = &snap_phdr;
}
if (choplen > 0 && phdr->caplen > (unsigned int) choplen) {
snap_phdr = *phdr;
snap_phdr.caplen -= choplen;
snap_phdr.len -= choplen;
buf += choplen;
phdr = &snap_phdr;
}
@ -1335,7 +1346,6 @@ main(int argc, char *argv[])
/* suppress duplicates by packet window */
if (dup_detect) {
buf = wtap_buf_ptr(wth);
if (is_duplicate(buf, phdr->caplen)) {
if (verbose) {
fprintf(stdout, "Skipped: %u, Len: %u, MD5 Hash: ", count, phdr->caplen);
@ -1365,8 +1375,6 @@ main(int argc, char *argv[])
current.secs = phdr->ts.secs;
current.nsecs = phdr->ts.nsecs;
buf = wtap_buf_ptr(wth);
if (is_duplicate_rel_time(buf, phdr->caplen, &current)) {
if (verbose) {
fprintf(stdout, "Skipped: %u, Len: %u, MD5 Hash: ", count, phdr->caplen);
@ -1392,7 +1400,6 @@ main(int argc, char *argv[])
/* Random error mutation */
if (err_prob > 0.0) {
int real_data_start = 0;
buf = wtap_buf_ptr(wth);
/* Protect non-protocol data */
if (wtap_file_type(wth) == WTAP_FILE_CATAPULT_DCT2000) {
real_data_start = find_dct2000_real_data(buf);
@ -1440,8 +1447,7 @@ main(int argc, char *argv[])
}
}
if (!wtap_dump(pdh, phdr, wtap_pseudoheader(wth), wtap_buf_ptr(wth),
&err)) {
if (!wtap_dump(pdh, phdr, wtap_pseudoheader(wth), buf, &err)) {
fprintf(stderr, "editcap: Error writing to %s: %s\n",
filename, wtap_strerror(err));
exit(2);