simply-tcp-server.c

simply-tcp-echo-server.c

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

#define BUFFER_SIZE 1024

int main(int argc, char** argv)
{
    if(argc != 2)
    {
        printf("Usage:\n%s <port>\n", argv[0]);
        return 0;
    }

    struct sockaddr_in myAddr, clientAddr;
    int socketFd, clientFd;
    unsigned int clientAddrLen = sizeof(clientAddr);
    int receivedLength;
    char buffer[BUFFER_SIZE];

    memset(&clientAddr, 0, sizeof(clientAddr));
    memset(&myAddr, 0, sizeof(myAddr));
    myAddr.sin_family = AF_INET;
    myAddr.sin_port = htons(atoi(argv[1]));
    // Listen 127.0.0.1
    myAddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    // or Listen 0.0.0.0
    //myAddr.sin_addr.s_addr = htonl(INADDR_ANY);

    socketFd = socket(AF_INET, SOCK_STREAM, 0);
    bind(socketFd, (struct sockaddr*)&myAddr, sizeof(myAddr));
    listen(socketFd, 5);
    clientFd = accept(socketFd, (struct sockaddr *)&clientAddr, &clientAddrLen);
    receivedLength = recv(clientFd, buffer, BUFFER_SIZE, 0);
    buffer[receivedLength] = '\0';
    printf("Received a message from %s:%u:\n%s\n"
        , inet_ntoa(clientAddr.sin_addr)
        , ntohs(clientAddr.sin_port),buffer);
    send(clientFd, buffer, receivedLength, 0);
    close(clientFd);
    close(socketFd);

    return 0;
}