TCP Boilerplate

tcp-client.c

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

#define SERVER_PORT 27070

int main(void)
{
    // Configure socket address
    struct sockaddr_in sa;
    memset(&sa, 0, sizeof(sa));

    sa.sin_family = AF_INET;
    sa.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, "127.0.0.1", &sa.sin_addr);

    // Obtain socket
    int sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (-1 == sock) {
        perror("tcp client - could not obtain socket");
        exit(EXIT_FAILURE);
    }

    if (-1 == connect(sock, (struct sockaddr *)&sa, sizeof(sa))) {
        perror("tcp client - connect failed");
        close(sock);
        exit(EXIT_FAILURE);
    }

    // data processing
    // read(), write(), etc

    // cleanup
    shutdown(sock, SHUT_RDWR);
    close(sock);

    return 0;
}

tcp-server.c

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

#define SERVER_PORT 27070

int main(void)
{
    // Server configuration
    struct sockaddr_in server;
    memset(&server, 0, sizeof(server));

    server.sin_family = AF_INET;
    server.sin_port = htons(SERVER_PORT);
    server.sin_addr.s_addr = htonl(INADDR_ANY);

    // Start the try/check dance
    int sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (-1 == sock) {
        perror("tcp server - could not create socket");
        exit(EXIT_FAILURE);
    }

    if (-1 == bind(sock, (struct sockaddr *)&server, sizeof(server))) {
        perror("tcp server - bind failed");
        close(sock);
        exit(EXIT_FAILURE);
    }

    if (-1 == listen(sock, 10)) {
        perror("tcp server - listen failed");
        close(sock);
        exit(EXIT_FAILURE);
    }

    // Client connection information
    struct sockaddr_in client;
    memset(&client, 0, sizeof(client));
    socklen_t fromlen = sizeof(client);

    while (1) {
        int connection = accept(sock, (struct sockaddr *)&client, &fromlen);
        if (connection < 0) {
            perror("tcp server - accept failed");
            close(sock);
            exit(EXIT_FAILURE);
        }

        // data processing
        // read(), write(), etc using connection socket above

        if (-1 == shutdown(connection, SHUT_RDWR)) {
            perror("tcp server - could not shutdown socket");
            close(connection);
            close(sock);
            exit(EXIT_FAILURE);
        }

        close(connection);
    }

    close(sock);
    return 0;
}