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/* Trivial libtrace program that writes all SMTP packets from a trace into
* a new separate trace.
*
* Designed to demonstrate the use of the libtrace output API
*/
#include "libtrace.h"
#include <stdio.h>
#include <inttypes.h>
#include <assert.h>
#include <getopt.h>
static int per_packet(libtrace_out_t *output, libtrace_packet_t *packet)
{
libtrace_tcp_t *tcp;
/* Get the TCP header using trace_get_tcp() */
tcp = trace_get_tcp(packet);
/* If the packet does not have a TCP header, skip it */
if (tcp == NULL)
return 0;
/* Check if either port in the TCP header is 25. Note that we
* have to byteswap the port numbers because we are reading directly
* out of the zero-copied packet */
if ((ntohs(tcp->source) == 25) || (ntohs(tcp->dest) == 25)) {
/* If we have a match, write the packet to our output trace,
* being sure to check for errors */
if (trace_write_packet(output, packet) == -1) {
trace_perror_output(output, "Writing packet");
return -1;
}
}
return 0;
}
/* The cleanup function has now been extended to destroy the output trace as
* well */
static void libtrace_cleanup(libtrace_t *trace, libtrace_out_t *output,
libtrace_packet_t *packet) {
/* It's very important to ensure that we aren't trying to destroy
* a NULL structure, so each of the destroy calls will only occur
* if the structure exists */
if (trace)
trace_destroy(trace);
if (output)
trace_destroy_output(output);
if (packet)
trace_destroy_packet(packet);
}
int main(int argc, char *argv[])
{
/* Unlike most of the other example programs, this is not a copy and
* paste job from readdemo.c as we now also have to initalise and
* start an output trace too */
libtrace_t *trace = NULL;
libtrace_packet_t *packet = NULL;
libtrace_out_t *output = NULL;
/* Check that we have all the required command line arguments */
if (argc < 3) {
fprintf(stderr, "Usage: %s inputURI outputURI\n", argv[0]);
return 1;
}
/* Creating the packet structure */
packet = trace_create_packet();
if (packet == NULL) {
perror("Creating libtrace packet");
libtrace_cleanup(trace, output, packet);
return 1;
}
/* Creating and starting the INPUT trace */
trace = trace_create(argv[1]);
if (trace_is_err(trace)) {
trace_perror(trace,"Opening trace file");
libtrace_cleanup(trace, output, packet);
return 1;
}
if (trace_start(trace) == -1) {
trace_perror(trace,"Starting trace");
libtrace_cleanup(trace, output, packet);
return 1;
}
/* Creating and starting the OUTPUT trace */
output = trace_create_output(argv[2]);
if (trace_is_err_output(output)) {
trace_perror_output(output,"Opening output trace file");
libtrace_cleanup(trace, output, packet);
return 1;
}
if (trace_start_output(output) == -1) {
trace_perror_output(output,"Starting output trace");
libtrace_cleanup(trace, output, packet);
return 1;
}
while (trace_read_packet(trace,packet)>0) {
/* If something goes wrong when writing packets, we need to
* catch that error, tidy up and exit */
if (per_packet(output, packet) == -1) {
libtrace_cleanup(trace, output, packet);
return 1;
}
}
/* Checking for any errors that might have occurred while reading the
* input trace */
if (trace_is_err(trace)) {
trace_perror(trace,"Reading packets");
libtrace_cleanup(trace, output, packet);
return 1;
}
libtrace_cleanup(trace, output, packet);
return 0;
}
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