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#include <stdio.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include "icmp.h"
#include "util.h"
struct state {
int socket;
};
#if 0
static int icmp_callback(struct nflog_data *ldata, void *state_) {
(void)gh; (void)nfmsg;
struct state *state = (struct state*)state_;
uint8_t *ip_start; // received packet, starting at the IP buffer
int ip_len = nflog_get_payload(ldata, (char**)&ip_start);
struct iphdr *hdr = (struct iphdr*)ip_start;
int hdr_len = hdr->ihl * 4;
uint32_t saddr = hdr->saddr;
struct icmp_echo *msg = (struct icmp_echo*)(ip_start + hdr_len);
int msg_len = ip_len - hdr_len;
printf("Received: type %u code %u id %hu seqnum %hu payload:\n",
(unsigned)msg->type, (unsigned)msg->code, msg->id, msg->seqnum);
xxd(msg->payload, msg_len - offsetof(struct icmp_echo, payload));
uint8_t *saddr_bytes = (uint8_t*)&saddr;
char ip_address[16];
sprintf(ip_address, "%u.%u.%u.%u", saddr_bytes[0], saddr_bytes[1], saddr_bytes[2], saddr_bytes[3]);
if (icmp_send_echo_reply(ip_address, msg->id, msg->seqnum, "dank je wel", 11) < 0) {
perror("icmp_send_echo_reply");
}
return 0;
}
#endif
int main(void) {
// struct state state;
// state.socket = icmp_open_socket();
// if (state.socket < 0) {
// perror("icmp_open_socket");
// return 1;
// }
int sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
struct icmp_echo msg;
char buf[MAX_IP_PACKET_SIZE];
while (true) {
struct iovec iov1;
memset(&iov1, 0, sizeof iov1);
iov1.iov_base = buf;
iov1.iov_len = sizeof buf;
struct sockaddr_in addr;
struct msghdr recv_msghdr;
memset(&recv_msghdr, 0, sizeof recv_msghdr);
recv_msghdr.msg_name = &addr;
recv_msghdr.msg_namelen = sizeof addr;
recv_msghdr.msg_iov = &iov1;
recv_msghdr.msg_iovlen = 1;
ssize_t nr = recvmsg(sock, &recv_msghdr, 0);
if (nr < 0) break;
// buf now contains received data starting at the IP header
printf("Full packet received:\n");
xxd(buf, nr);
struct iphdr *hdr = (struct iphdr*)buf;
int hdr_len = hdr->ihl * 4;
uint32_t saddr = hdr->saddr;
struct icmp_echo *msg = (struct icmp_echo*)(buf + hdr_len);
int msg_len = nr - hdr_len;
printf("Received: type %u code %u id %hu seqnum %hu payload:\n",
(unsigned)msg->type, (unsigned)msg->code, msg->id, msg->seqnum);
xxd(msg->payload, msg_len - offsetof(struct icmp_echo, payload));
if (msg->type != ICMP_ECHO) {
printf("Not an ICMP_ECHO, ignoring\n");
continue;
}
uint8_t *saddr_bytes = (uint8_t*)&saddr;
char ip_address[16];
sprintf(ip_address, "%u.%u.%u.%u", saddr_bytes[0], saddr_bytes[1], saddr_bytes[2], saddr_bytes[3]);
if (icmp_send_echo_reply(ip_address, msg->id, msg->seqnum, "dank je wel", 11) < 0) {
perror("icmp_send_echo_reply");
}
}
}
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