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implement ip_send

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This commit is contained in:
mykola2312 2024-12-19 18:46:10 +02:00
parent ae8863ccc5
commit 075a8bd3bc
1 changed files with 38 additions and 7 deletions
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45
main.c
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@ -185,6 +185,32 @@ uint16_t checksum(const uint8_t* data, size_t len) {
return ~((uint16_t)sum);
}
ssize_t ip_send(struct linkinterface* link, const uint8_t* dstAddr,
const uint8_t* dstIp, uint8_t proto, frame_t frame, size_t len)
{
// shift data to add space for IP header
size_t iplen = sizeof(struct ip) + len;
frame = realloc(frame, iplen);
memmove((uint8_t*)frame + sizeof(struct ip), frame, len);
// create IP packet
struct ip* ip = (struct ip*)frame;
ip->ip_v = 4;
ip->ip_hl = sizeof(struct ip) / 4;
ip->ip_tos = 0;
ip->ip_len = htons(iplen);
ip->ip_id = (uint16_t)rand();
ip->ip_off = 0;
ip->ip_ttl = 64;
ip->ip_p = proto;
ip->ip_sum = 0;
memcpy(&ip->ip_src, link->host_ip, 4);
memcpy(&ip->ip_dst, dstIp, 4);
// calculate header checksum
ip->ip_sum = htons(checksum((const uint8_t*)frame, sizeof(struct ip)));
return link_send(link, dstAddr, ETHERTYPE_IP, frame, iplen);
}
int main(int argc, char** argv) {
// ifname targetMAC
struct linkinterface* link = link_open(argv[1]);
@ -201,18 +227,23 @@ int main(int argc, char** argv) {
uint16_t id = (uint16_t)rand();
// ICMP request
struct icmphdr icmp;
icmp.type = ICMP_ECHO;
icmp.code = 0;
icmp.checksum = 0;
icmp.un.echo.id = (uint16_t)rand();
icmp.un.echo.sequence = 1;
struct icmphdr* icmp = frame_new(sizeof(struct icmphdr));
icmp->type = ICMP_ECHO;
icmp->code = 0;
icmp->checksum = 0;
icmp->un.echo.id = (uint16_t)rand();
icmp->un.echo.sequence = 1;
// calculate checksum
icmp.checksum = htons(checksum((const uint8_t*)&icmp, sizeof(icmp)));
icmp->checksum = htons(checksum(
(const uint8_t*)&icmp, sizeof(struct icmphdr)));
// IPv4 local broadcast
uint8_t ip_broadcast[4] = {255, 255, 255, 255};
ssize_t sent = ip_send(link, target, ip_broadcast,
IPPROTO_ICMP, icmp, sizeof(struct icmphdr));
printf("sent %ld\n", sent);
link_free(link);
return 0;
}