nettest.c

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

void server(int sock)
{
    char buffer[256];
    int cur_seq = 0;
    int cur_count = 0;
    ssize_t size;
    while(1)
    {   
        int seq, n;
        size = recv(sock, buffer, 256, 0); 
        if(size == sizeof(int)*2)
        {   
            seq = ((int*)buffer)[0];
            n = ((int*)buffer)[1];
            if(seq == cur_seq)
                cur_count++;
            else
            {   
                printf("Received %d packets for seq %d\n", cur_count, cur_seq);
                cur_seq = seq;
                cur_count = 1;
            }   
        }   
        else
            printf("Discarded a packet");
    }   
}

void client(int sock)
{
    char buffer[256];
    unsigned int seq, n;
    for(seq = 0;; seq++)
    {   
        for(n = 0;n < 1024; n++)
        {   
            ((int*)buffer)[0] = seq;
            ((int*)buffer)[1] = n;
            send(sock, buffer, 2*sizeof(int), 0);
        }
        sleep(1);
    }
}

int main(int argc, char *argv[])
{
    int sock, port;
    if(argc < 3)
    {
        printf("Not enough arguments.\n");
        return;
    }   
    sock = socket(AF_INET, SOCK_DGRAM, 0);
    if(strcmp(argv[1], "-s") == 0)
    {   
        struct sockaddr_in sockaddr;
        memset((void*)&sockaddr, 0, sizeof(sockaddr));
        port = atoi(argv[2]);
        sockaddr.sin_family = AF_INET;
        sockaddr.sin_addr.s_addr = INADDR_ANY;
        sockaddr.sin_port = htons(port);
        if(bind(sock, (struct sockaddr*) &sockaddr, sizeof(sockaddr)) != 0)
            printf("Could not bind to port %d\n", port);
        else    
            server(sock); 
    }       
    else if(strcmp(argv[1], "-c") == 0)
    {   
        struct addrinfo hints, *result;
        hints.ai_family = AF_INET;
        hints.ai_socktype = SOCK_DGRAM;
        hints.ai_flags = AI_ALL;
        hints.ai_protocol = 0;
        hints.ai_canonname = NULL;
        hints.ai_addr = NULL;
        hints.ai_next = NULL;
        if(getaddrinfo(argv[2], argv[3], &hints, &result) != 0)
            printf("Could not resolve %s\n", argv[2]);
        else
        {   
            if(connect(sock, result->ai_addr, result->ai_addrlen) != 0)
                printf("Could not connect on %s:%s\n", argv[2], argv[3]);
            else
                client(sock);
            freeaddrinfo(result);
        }   
    }   
    else
        printf("Not a valid mode, try -s or -c");
    close(sock);
}