icmp.cpp

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#include <net/icmp.h>
 
using namespace  MaxOS;
using namespace  MaxOS::common;
using namespace  MaxOS::net;
 
InternetControlMessageProtocol::InternetControlMessageProtocol(InternetProtocolHandler *internet_protocol_handler, OutputStream* error_messages)
: IPV4PayloadHandler(internet_protocol_handler, 0x01)
{
    this -> error_messages = error_messages;
}
 
 
 
InternetControlMessageProtocol::~InternetControlMessageProtocol() = default;
bool InternetControlMessageProtocol::handle_internet_protocol_payload(net::InternetProtocolAddress src_ip_be,
                                                                      net::InternetProtocolAddress dst_ip_be,
                                                                      uint8_t *payload_data,
                                                                      uint32_t size)
{
 
    error_messages -> write("ICMP received a packet\n");
 
    // Check if the size is at least the size of the header
    if(size < sizeof(ICMPHeader)){
        return false;
    }
 
    // Cast the payload to the ICMP header
    auto* icmp = (ICMPHeader*)payload_data;
 
    switch (icmp -> type) {
 
        case 0: // Echo reply
            break;
 
        case 8: // Echo request
 
            // Create a response
            icmp -> type = 0;                                                                                                                    // Echo reply
            icmp -> checksum = 0;                                                                                                                // Reset the checksum
            icmp -> checksum = InternetProtocolHandler::checksum((uint16_t*) &icmp, sizeof(ICMPHeader));             // Calculate the checksum
 
            return true;    //Send data back
 
    }
 
    return false;
 
}
 
void InternetControlMessageProtocol::request_echo_reply(uint32_t ip_be) {
 
    error_messages -> write("ICMP: Sending echo request\n");
 
    ICMPHeader icmp = {};
    icmp.type = 8;                      // Echo request
    icmp.code = 0;                      // Code must be 0
    icmp.checksum = 0;                  // Checksum must be 0 to calculate it
    icmp.data = 0x69420;        // Data
 
    icmp.checksum = InternetProtocolHandler::checksum((uint16_t*) &icmp, sizeof(ICMPHeader));
 
    send(ip_be, (uint8_t*) &icmp, sizeof(ICMPHeader));
 
    error_messages -> write("ICMP: Echo request sent\n");
}