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support raw ip captures (no link layer) by faking it

This commit is contained in:
pi-rho 2013-02-05 12:59:44 -06:00
parent ddfda783bd
commit 249e959fcc
3 changed files with 108 additions and 62 deletions
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38
src/pcap.c
View File

@ -3,8 +3,8 @@
*
*/
#include <err.h>
#include <stdio.h>
#include <sysexits.h>
#include <string.h>
#include "pcap.h"
#include "netre.h"
@ -21,6 +21,8 @@ int pcap_open_in(struct pcap_file *ctx, FILE *f) {
ctx->swap = 1;
DDUMP("swapped order");
} else {
DDUMP("bad magic");
warnx("unsupported packet capture");
return -1;
}
if ((h.version_major != 2) || (h.version_minor != 4)) return -1;
@ -29,7 +31,18 @@ int pcap_open_in(struct pcap_file *ctx, FILE *f) {
if (ctx->swap != 0) h.snaplen = bswap32(h.snaplen);
DDUMP_d(h.snaplen);
if (h.snaplen > MAXFRAME) return -1;
if (h.snaplen > MAXFRAME) {
DDUMP("bad snaplen");
warnx("PCAP snaplength too large (%d > %d)", h.snaplen, MAXFRAME);
return -1;
}
DDUMP_x(h.linktype);
if (h.linktype == 101) {
ctx->raw = 1;
} else {
ctx->raw = 0;
}
ctx->f = f;
return 0;
@ -38,7 +51,10 @@ int pcap_open_in(struct pcap_file *ctx, FILE *f) {
int pcap_open_out(struct pcap_file *ctx, FILE *f) {
struct pcap_file_header h = { MAGIC, 2, 4, 0, 0, MAXFRAME, 1 };
if (fwrite(&h, sizeof(h), 1, f) != 1) return -1;
if (fwrite(&h, sizeof(h), 1, f) != 1) {
warn("unable to open file");
return -1;
}
ctx->f = f;
ctx->swap = 0;
@ -56,7 +72,11 @@ int pcap_read_pkthdr(struct pcap_file *ctx, struct pcap_pkthdr *hdr) {
hdr->len = bswap32(hdr->len);
}
if (hdr->caplen > MAXFRAME) return -1;
if (hdr->caplen > MAXFRAME) {
DDUMP("bad snaplen");
warnx("packet header capture length too large (%d > %d)", hdr->caplen, MAXFRAME);
return -1;
}
return 0;
}
@ -71,9 +91,15 @@ int pcap_write_pkthdr(struct pcap_file *ctx, struct pcap_pkthdr *hdr) {
hdr->caplen = bswap32(hdr->caplen);
hdr->len = bswap32(hdr->len);
if (fwrite(&ohdr, sizeof(ohdr), 1, ctx->f) != 1) return -1;
if (fwrite(&ohdr, sizeof(ohdr), 1, ctx->f) != 1) {
warn("failed to write packet header");
return -1;
}
} else {
if (fwrite(hdr, sizeof(*hdr), 1, ctx->f) != 1) return -1;
if (fwrite(hdr, sizeof(*hdr), 1, ctx->f) != 1) {
warn("failed to write packet header");
return -1;
}
}
return 0;

2
src/pcap.h
View File

@ -10,6 +10,7 @@
struct pcap_file {
FILE *f;
int swap;
int raw;
};
struct pcap_file_header {
@ -43,6 +44,7 @@ struct pcap_pkthdr {
((i & 0x00ff0000) >> 010) | \
((i & 0x0000ff00) << 010) | \
((i & 0x000000ff) << 030))
#define bswap16(i) (((i & 0xff00) >> 010) | \
((i & 0x00ff) << 010))

20
src/pmerge.c
View File

@ -24,6 +24,12 @@ struct input_file {
struct pcap_pkthdr next;
};
struct linklayer {
uint16_t src[3];
uint16_t dest[3];
uint16_t ethertype;
};
int version(bool error) {
fprintf(WHICHOUT(error), "pmerge v.%s - %s\n\n", PACKAGE_VERSION,
"Merges pcap files, outputting time-ordered pcap stream");
@ -41,7 +47,7 @@ int usage(bool error, char *prog) {
int read_next(struct input_file *file) {
if (! file->active) return -1;
if (-1 == pcap_read_pkthdr(&file->p, &file->next)) {
if (pcap_read_pkthdr(&file->p, &file->next) == -1) {
pcap_close(&file->p);
file->active = 0;
file->next.ts.tv_sec = 0xffffffff;
@ -56,6 +62,7 @@ int pmerge(FILE *output, struct input_file files[], int nfiles) {
int nopen;
int i;
struct pcap_file out;
struct linklayer fake = {{0,0,0}, {1,1,1}, 0x0008};
if (pcap_open_out(&out, output) == -1) {
perror("writing pcap header");
@ -95,10 +102,20 @@ int pmerge(FILE *output, struct input_file files[], int nfiles) {
/* Write header + frame */
if (len) {
if (cur->p.raw) {
cur->next.caplen += sizeof(fake);
cur->next.len += sizeof(fake);
}
if (fwrite(&cur->next, sizeof(cur->next), 1, output) != 1) {
perror("error");
return EX_IOERR;
}
if (cur->p.raw) {
if (fwrite(&fake, sizeof(fake), 1, output) != 1) {
perror("error");
return EX_IOERR;
}
}
if (len != fwrite(frame, 1, len, output)) {
perror("error");
return EX_IOERR;
@ -150,6 +167,7 @@ int main(int argc, char *argv[]) {
return EX_NOINPUT;
}
/* prime the input files */
if (pcap_open_in(&cur->p, f) == -1) {
fprintf(stderr, "%s: unable to process\n", fn);
return EX_IOERR;