Question #234832 on rohc changed:
https://answers.launchpad.net/rohc/+question/234832
Status: Needs information => Open
manish shivare gave more information on the question:
manish@manish-HP-630-Notebook-PC:~/rohc-1.6.1/examples$ gcc -o
simple_rohc_program -g -Wall $(pkg-config rohc --libs) simple_rohc_program.c
code is given by you-
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file simple_rohc_program.c
* @brief A simple program that uses the compression part of the ROHC library
* @author Didier Barvaux <[email protected]>
*
* This simple program was first published on the mailing list dedicated to the
* ROHC library. Ask your questions about this example there.
*
* Mailing list subscription: http://launchpad.net/~rohc/+join
* Mailing list public archives: http://lists.launchpad.net/rohc/
*/
/* system includes */
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <string.h>
#include "config.h" /* for HAVE_*_H definitions */
#if HAVE_WINSOCK2_H == 1
# include <winsock2.h> /* for htons() on Windows */
#endif
#if HAVE_ARPA_INET_H == 1
# include <arpa/inet.h> /* for htons() on Linux */
#endif
/* includes required to use the compression part of the ROHC library */
#include <rohc.h>
#include <rohc_comp.h>
/** The size (in bytes) of the buffers used in the program */
#define BUFFER_SIZE 2048
/** The payload for the fake IP packet */
#define FAKE_PAYLOAD "hello, ROHC world!"
static int gen_random_num(const struct rohc_comp *const comp,
void *const user_context);
/**
* @brief The main entry point for the simple ROHC program
*
* @param argc The number of arguments given to the program
* @param argv The table of arguments given to the program
* @return 0 in case of success, 1 otherwise
*/
int main(int argc, char **argv)
{
struct rohc_comp *compressor; /* the ROHC compressor */
unsigned char ip_packet[BUFFER_SIZE]; /* the buffer that will contain
the IPv4 packet to compress
*/
size_t ip_packet_len; /* the length (in bytes) of the
IPv4 packet */
unsigned char rohc_packet[BUFFER_SIZE]; /* the buffer that will contain
the resulting ROHC packet */
size_t rohc_packet_len; /* the length (in bytes) of the
resulting ROHC packet */
unsigned int seed;
size_t i;
int ret;
/* initialize the random generator */
seed = time(NULL);
srand(seed);
/* Create a ROHC compressor with small CIDs, no jamming and no
adaptation
* to encapsulation frames.
*
* See
http://rohc-lib.org/doc/latest/group__rohc__comp.html#ga721fd34fc0cd9e1d789b693eb6bb6485
* for details about rohc_alloc_compressor in the API documentation.
*/
printf("\ncreate the ROHC compressor\n");
compressor = rohc_alloc_compressor(ROHC_SMALL_CID_MAX, 0, 0, 0);
if(compressor == NULL)
{
fprintf(stderr, "failed create the ROHC compressor\n");
goto error;
}
/* set the callback for random numbers */
if(!rohc_comp_set_random_cb(compressor, gen_random_num, NULL))
{
fprintf(stderr, "failed to set the callback for random
numbers\n");
goto release_compressor;
}
/* Enable the compression profiles you need (comment or uncomment some
lines).
*
* See
http://rohc-lib.org/doc/latest/group__rohc__comp.html#ga1a444eb91681521f726712a60a4df867
* for details about rohc_activate_profile in the API documentation.
*/
printf("\nenable several ROHC compression profiles\n");
rohc_activate_profile(compressor, ROHC_PROFILE_UNCOMPRESSED);
//rohc_activate_profile(compressor, ROHC_PROFILE_UDP);
rohc_activate_profile(compressor, ROHC_PROFILE_IP);
//rohc_activate_profile(compressor, ROHC_PROFILE_UDPLITE);
//rohc_activate_profile(compressor, ROHC_PROFILE_RTP);
//rohc_activate_profile(comp, ROHC_PROFILE_ESP);
/* create a fake IP packet for the purpose of this simple program */
printf("\nbuild a fake IP packet\n");
ip_packet[0] = 4 << 4; /* IP version 4 */
ip_packet[0] |= 5; /* IHL: minimal IPv4 header length (in 32-bit words)
*/
ip_packet[1] = 0; /* TOS */
ip_packet_len = 5 * 4 + strlen(FAKE_PAYLOAD);
ip_packet[2] = (ip_packet_len >> 8) & 0xff; /* Total Length */
ip_packet[3] = ip_packet_len & 0xff;
ip_packet[4] = 0; /* IP-ID */
ip_packet[5] = 0;
ip_packet[6] = 0; /* Fragment Offset and IP flags */
ip_packet[7] = 0;
ip_packet[8] = 1; /* TTL */
ip_packet[9] = 134; /* Protocol: unassigned number */
ip_packet[10] = 0xbe; /* fake Checksum */
ip_packet[11] = 0xef;
ip_packet[12] = 0x01; /* Source address */
ip_packet[13] = 0x02;
ip_packet[14] = 0x03;
ip_packet[15] = 0x04;
ip_packet[16] = 0x05; /* Destination address */
ip_packet[17] = 0x06;
ip_packet[18] = 0x07;
ip_packet[19] = 0x08;
/* copy the payload just after the IP header */
memcpy(ip_packet + 5 * 4, FAKE_PAYLOAD, strlen(FAKE_PAYLOAD));
/* dump the newly-created IP packet on terminal */
for(i = 0; i < ip_packet_len; i++)
{
printf("0x%02x ", ip_packet[i]);
if(i != 0 && ((i + 1) % 8) == 0)
{
printf("\n");
}
}
if(i != 0 && ((i + 1) % 8) != 0) /* be sure to go to the line */
{
printf("\n");
}
/* Now, compress this fake IP packet.
*
* See
http://rohc-lib.org/doc/latest/group__rohc__comp.html#ga99be8242b7bc4f442f4519461a99726b
* for details about rohc_compress in the API documentation.
*/
printf("\ncompress the fake IP packet\n");
ret = rohc_compress2(compressor,
ip_packet, ip_packet_len,
rohc_packet, BUFFER_SIZE, &rohc_packet_len);
if(ret != ROHC_OK)
{
fprintf(stderr, "compression of fake IP packet failed\n");
goto release_compressor;
}
/* dump the ROHC packet on terminal */
printf("\nROHC packet resulting from the ROHC compression:\n");
for(i = 0; i < rohc_packet_len; i++)
{
printf("0x%02x ", rohc_packet[i]);
if(i != 0 && ((i + 1) % 8) == 0)
{
printf("\n");
}
}
if(i != 0 && ((i + 1) % 8) != 0) /* be sure to go to the line */
{
printf("\n");
}
/* Release the ROHC compressor when you do not need it anymore.
*
* See
http://rohc-lib.org/doc/latest/group__rohc__comp.html#ga736ea1760d7af54ad903c29765df5bd3
* for details about rohc_free_compressor in the API documentation.
*/
printf("\n\ndestroy the ROHC decompressor\n");
rohc_free_compressor(compressor);
printf("\nThe program ended successfully. The ROHC packet is larger
than the "
"IP packet (39 bytes versus 38 bytes). This is expected since we
only "
"compress one packet in this simple example. Keep in mind that
ROHC "
"is designed to compress streams of packets not one single
packet.\n\n");
return 0;
release_compressor:
rohc_free_compressor(compressor);
error:
fprintf(stderr, "an error occured during program execution, "
"abort program\n");
return 1;
}
/**
* @brief Generate a random number
*
* @param comp The ROHC compressor
* @param user_context Should always be NULL
* @return A random number
*/
static int gen_random_num(const struct rohc_comp *const comp,
void *const user_context)
{
return rand();
}
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