Creating the server socket

Before entertaining the exciting parts of the HTTP server, such as message parsing, let's get the basics out of the way. Our HTTP server, like all servers, needs to create a listening socket to accept new connections. We define a function, create_socket(), for this purpose. This function begins by using getaddrinfo() to find the listening address:

/*web_server.c except*/

SOCKET create_socket(const char* host, const char *port) {
    printf("Configuring local address...\n");
    struct addrinfo hints;
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE;

    struct addrinfo *bind_address;
    getaddrinfo(host, port, &hints, &bind_address);

create_socket() then continues with creating a socket using socket(), binding that socket to the listening address with bind(), and having the socket enter a listening state with listen(). The following code calls these functions while detecting error conditions:

/*web_server.c except*/

    printf("Creating socket...\n");
    SOCKET socket_listen;
    socket_listen = socket(bind_address->ai_family,
            bind_address->ai_socktype, bind_address->ai_protocol);
    if (!ISVALIDSOCKET(socket_listen)) {
        fprintf(stderr, "socket() failed. (%d)\n", GETSOCKETERRNO());
        exit(1);
    }

    printf("Binding socket to local address...\n");
    if (bind(socket_listen,
                bind_address->ai_addr, bind_address->ai_addrlen)) {
        fprintf(stderr, "bind() failed. (%d)\n", GETSOCKETERRNO());
        exit(1);
    }
    freeaddrinfo(bind_address);

    printf("Listening...\n");
    if (listen(socket_listen, 10) < 0) {
        fprintf(stderr, "listen() failed. (%d)\n", GETSOCKETERRNO());
        exit(1);
    }

    return socket_listen;
}

The preceding code should be very familiar to you if you're working through this book in order. If not, please refer to Chapter 3, An In-Depth Overview of TCP Connections, for information about setting up TCP servers.