echosrv.c

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

#define SERVERPORT 2050
#define SERVERADDRESS "127.0.0.1"

int main(int argc, char * argv[])
{
    int server_socket, connect_socket, retcode;
    socklen_t client_addr_len;
    struct sockaddr_in server_addr, client_addr;
    char buffer[1];
    char* client_address;

    if (((server_socket = socket(AF_INET,SOCK_STREAM,0))) == -1)
    {
        perror("Error in server socket()");
        exit(-1);
    }

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVERPORT);
    server_addr.sin_addr.s_addr = inet_addr(SERVERADDRESS);

    if ((retcode = bind (server_socket, (struct sockaddr*)  &server_addr, sizeof(server_addr))) == -1)
    {
        perror("Error in server socket bind()");
        exit(-1);
    }

    if ((retcode = listen(server_socket, 1)) == -1)
    {
        perror("Error in server socket listen()");
        exit(-1);
    }

    printf("Server ready (CTRL-C quits)\n");

    client_addr_len = sizeof(client_addr);

    while (1)
    {
        if ((connect_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addr_len)) == -1)
        {
            perror("Error in accept()");
            close(server_socket);
            exit(-1);
        }

        client_address = inet_ntoa(client_addr.sin_addr);

        printf("\nClient @ %s connects on socket %d\n", client_address, connect_socket);

        while ((read(connect_socket, buffer, 1)) != -1)
        {
            printf("reading 1 byte\n");
            write(connect_socket, buffer, 1);
        }
        printf("exiting\n");

        //close(connect_socket);
    }
}