echo_request_t prepare_echo_request(unsigned short identifier, unsigned char *local_ip, unsigned char *local_mac, unsigned char *dest_ip, unsigned char *dest_mac) {
char *buffer = calloc(sizeof(char), BUFFER_LEN);
char *bufferptr = buffer;
// Prepare packet data as needed
bufferptr = write_ethernet(bufferptr, dest_mac, local_mac);
bufferptr = write_ipv4(bufferptr, identifier + sequence_number, local_ip, dest_ip);
bufferptr = write_icmp(bufferptr, identifier);
echo_request_t req = {
.identifier = identifier,
.sequence_number = sequence_number++,
.local_mac = local_mac,
.local_ip = local_ip,
.raw_packet = buffer
};
return req;
}
// Write the ethernet headers
char *write_ethernet(char *bufferptr, unsigned char *dest_mac, unsigned char *local_mac) {
memcpy(bufferptr, dest_mac, MAC_ADDR_LEN);
bufferptr += MAC_ADDR_LEN;
memcpy(bufferptr, local_mac, MAC_ADDR_LEN);
bufferptr += MAC_ADDR_LEN;
short int etherTypeT = htons(0x0800);
memcpy(bufferptr, &(etherTypeT), sizeof(etherTypeT));
return bufferptr + ETHERTYPE_LEN;
}
int write_token_ip_entry(FILE* h_token2ip, const char* token, uint8_t* ip) {
if (!write_string(h_token2ip, token))
return 0;
if (!write_ipv4(h_token2ip, ip))
return 0;
return 1;
}
