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Code

Added transmission function for IPv4 packets

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This one lets OS to provide the ethernet header
This commit is contained in:
Michal Zima 2012-03-29 22:03:57 +02:00
parent b9d5b08b0f
commit 94cbbb5c53
2 changed files with 55 additions and 5 deletions
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57
src/transmitter.c
View File

@ -22,6 +22,7 @@
#include <netinet/in.h> /* htons */
#include <netpacket/packet.h> /* sockaddr_ll, PACKET_OTHERHOST */
#include <stdio.h> /* fprintf, stderr, perror */
#include <string.h> /* memcpy */
#include <unistd.h> /* close */
#include "ipv4.h"
@ -29,7 +30,8 @@
#include "wrapper.h"
struct sockaddr_ll socket_address;
int sock;
struct sockaddr_in socket_address_ipv4;
int sock, sock_ipv4;
/**
* Initialize socket and all needed properties. Should be called only once on program startup.
@ -39,6 +41,9 @@ int sock;
*/
int transmission_init(void)
{
unsigned char on = 1;
/** RAW socket **/
/* prepare settings for RAW socket */
socket_address.sll_family = PF_PACKET; /* RAW communication */
socket_address.sll_protocol = htons(ETH_P_IP); /* protocol above the ethernet layer */
@ -59,6 +64,26 @@ int transmission_init(void)
return 1;
}
/** IPv4 socket **/
/* prepare settings for RAW IPv4 socket */
socket_address_ipv4.sin_family = AF_INET;
socket_address_ipv4.sin_port = 0x0;
/* initialize RAW IPv4 socket */
if ((sock_ipv4 = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) == -1) {
fprintf(stderr, "[Error] Couldn't open RAW IPv4 socket.\n");
perror("socket()");
return 1;
}
/* we will provide our own IPv4 header */
if (setsockopt(sock_ipv4, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on)) == -1) {
fprintf(stderr, "[Error] Couldn't apply the socket settings.\n");
perror("setsockopt()");
return 1;
}
return 0;
}
@ -71,8 +96,8 @@ int transmission_init(void)
int transmission_quit(void)
{
/* close the socket */
if (close(sock)) {
fprintf(stderr, "[Error] Couldn't close the transmission socket.\n");
if (close(sock) || close(sock_ipv4)) {
fprintf(stderr, "[Error] Couldn't close the transmission sockets.\n");
perror("close()");
return 1;
} else {
@ -89,7 +114,7 @@ int transmission_quit(void)
* @return 0 for success
* @return 1 for failure
*/
int transmit(unsigned char *data, unsigned int length)
int transmit_raw(unsigned char *data, unsigned int length)
{
if (sendto(sock, data, length, 0, (struct sockaddr *) &socket_address, sizeof(struct sockaddr_ll)) != length) {
fprintf(stderr, "[Error] Couldn't send a RAW packet.\n");
@ -99,3 +124,27 @@ int transmit(unsigned char *data, unsigned int length)
return 0;
}
/**
* Send IPv4 packet with IPv4 header supplied. Ethernet header is added by OS.
*
* @param ip Destination IPv4 address
* @param data Raw packet data, excluding ethernet header, but including IPv4 header
* @param length Length of the whole packet in bytes
*
* @return 0 for success
* @return 1 for failure
*/
int transmit_ipv4(struct s_ipv4_addr *ip, unsigned char *data, unsigned int length)
{
/* set the destination IPv4 address */
memcpy(&socket_address_ipv4.sin_addr.s_addr, ip, sizeof(struct s_ipv4_addr));
if (sendto(sock_ipv4, data, length, 0, (struct sockaddr *) &socket_address_ipv4, sizeof(struct sockaddr)) != length) {
fprintf(stderr, "[Error] Couldn't send an IPv4 packet.\n");
perror("sendto()");
return 1;
}
return 0;
}

3
src/transmitter.h
View File

@ -23,6 +23,7 @@
int transmission_init(void);
int transmission_quit(void);
int transmit(unsigned char *data, unsigned int length);
int transmit_raw(unsigned char *data, unsigned int length);
int transmit_ipv4(struct s_ipv4_addr *ip, unsigned char *data, unsigned int length);
#endif /* TRANSMITTER_H */