CODEWITHSUNDEEP
c++socketshexraw-sockets
Zeliax
Zeliax

Reputation: 5386

Read raw socket ip header? c++

I'm trying to figure out what an IP packet contains using raw sockets. I'm writing in C++ and so far I've been able to print out an entire packet using the following code:

int CreateRawSocket(int protocol_to_sniff)
{
     int s
     if(s = socket(PF_PACKET, SOCK_RAW, htons(protocol_to_sniff)
     {
          perror("Error creating raw socket");
          exit(1);
     }
     return s;
}

void PrintPacket(unsigned char *packet, int len)
{
     unsigned char *p = packet;

     printf("\n--Packet start--\n");
     while(len--)
     {
          printf("%.2x ", *p);
          p++;
     }
     printf("\n--Packet end--\n");
}

int main()
{
     int length, s, packets_to_sniff;
     unsigned char *packet_buffer;

     s = CreateRawSocket(ETH_P_ALL);

     if(s == -1)
     {
           perror("Error creating socket");
           exit(1);
     }

     packet_buffer = (unsigned char *)malloc(1518);

     printf("Number of packets to sniff?: ");
     cin >> packets_to_sniff;

     while(packets_to_sniff--)
     {
           length = recvfrom(s, packet_buffer, ETH_FRAME_LEN, 0, NULL, NULL);
           if(length == -1)
           {
                 perror("Error recieving packet");
                 exit(1);
           }
           else
           {
                 printf("Packet number: " + packets_to_sniff);
                 PrintPacket(packet_buffer, length);
           }
     }
}

I have a Virtual Machine pinging the one I'm programming on and all my program seems to print is the MAC frames of the packet which I think are in Hex..

I would like to be able to read the the IP Header and find out which fields of the Header contains what information.

Something a little like:

printf(packet_buffer[0]);
printf(packet_buffer[1]);

I've tried that without getting any output which seems wierd.

Best of regards!

Upvotes: 0

Views: 2969

Answers (2)

tristan
tristan

Reputation: 4312

as you know the size of IP header, you could print each byte as hex:

for (int i = 0; i < ip_header_length; i++)
    printf("%02x ", packet_buffer[i]);

Upvotes: 1

user146043
user146043

Reputation:

Have you tried dumping the contents of packet_buffer in hex, rather than treating it as a string consisting of printable characters?

Upvotes: 0

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