C & Socket Communication

Hi I'm working on a college project developing a Network Analyser using Libpcap. The Capture engine is built in C and GUI in Java and i'm using sockets ipc for communication. I have developed a prtocol, which both sides understand. The structure of the protocol is:

Message ID:
Message Type:
Session ID:
NO oF Parameters:
Parameter Length:
Parameter:

The problem is i have a basic TCP echo server in C which just echos the word hello to the client.

I want to know how would I decode the incomming message which has the above fields and how would I encode using the same above field to send the same message back to the client.

thanks
adam


The socket code is as follows:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <unistd.h>
#include <sys/time.h>

#define MAXPENDING 5

void DieWithError(char *charMessage);
void HandleTCPClient(int clntSocket);

int main(int argc, char *argv[])

{
        int servSock;
        int clntSock;
        struct sockaddr_in echoServAddr;
        struct sockaddr_in echoClntAddr;

        unsigned short echoServPort;
        unsigned short echoServPort;
        unsigned int clntLen;

        int i = 24;

        if (argc !=2)
        {
                fprintf(stderr, "Usage: %s <Server Port>\n", argv[0]);
                exit(1);
        }

        echoServPort = atoi(argv[1]);

        if((servSock= socket(PF_INET, SOCK_STREAM, IPPROTO_TCP))<0)
                DieWithError("socket()failed");
        memset(&echoServAddr,0,sizeof(echoServAddr));
        echoServAddr.sin_family = AF_INET;
        echoServAddr.sin_addr.s_addr = htonl(INADDR_ANY);
        echoServAddr.sin_port = htons(echoServPort);

        if(bind(servSock, (struct sockaddr *)&echoServAddr,sizeof(echoServAddr))<0) {
                DieWithError("bind() failed");
        }

        if(listen(servSock, MAXPENDING) < 0)

         DieWithError("listen() failed");
        /*for(i = 0; i <= 4; i++)
        {*/
                clntLen =sizeof(echoClntAddr);

                if((clntSock = accept(servSock,(struct sockaddr*)&echoClntAddr,&clntLen))<0)
                        DieWithError("accept()failed");

                printf("Handling client %s\n", inet_ntoa(echoClntAddr.sin_addr));
                HandleTCPClient(clntSock);
        /*}*/
        close(servSock);
        return(0);
}

void DieWithError(char *errorMessage)
{
        perror(errorMessage);
        exit(1);
}

void HandleTCPClient(int clntSocket)
{
        int sendrc;
        char greeting[44];
         strcpy(greeting, "This is a message from the C socket server.");

        if((sendrc = send(clntSocket, greeting, strlen(greeting),0))<0)
        {
                printf("Send failed\n");
                perror(NULL);
                exit(-1);
        }
        close(clntSocket);
}