tcp-ip-sockets-in-c/ch3/TCPServerUtility.c

#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#include "Practical.h"

static const int MAX_PENDING = 5;

int setup_tcp_server_socket(const char *service) {
    struct addrinfo addr_criteria = { 0 };
    addr_criteria.ai_family = AF_UNSPEC;
    addr_criteria.ai_flags = AI_PASSIVE;
    addr_criteria.ai_socktype = SOCK_STREAM;
    addr_criteria.ai_protocol = proto_get_num("tcp");

    struct addrinfo *serv_addr = nullptr;
    int ret = getaddrinfo(nullptr, service, &addr_criteria, &serv_addr);
    if (ret != 0) {
        DieWithUserMessage("getaddrinfo() failed", gai_strerror(ret));
    }

    int serv_sock = -1;
    for (struct addrinfo *addr = serv_addr; addr != nullptr; addr = addr->ai_next) {
        serv_sock = socket(AF_to_PF(addr->ai_family), addr->ai_socktype, addr->ai_protocol);
        if (serv_sock < 0) {
            continue;
        }

        if (
            (bind(serv_sock, addr->ai_addr, addr->ai_addrlen) == 0)
            && (listen(serv_sock, MAX_PENDING) == 0)
        ) {
            struct sockaddr_storage local_addr;
            socklen_t addr_size = sizeof(local_addr);
            if (getsockname(serv_sock, (struct sockaddr *) &local_addr, &addr_size) < 0) {
                DieWithSystemMessage("getsockname() failed");
            }
            fputs("Binding to: ", stdout);
            PrintSocketAddress((struct sockaddr *) &local_addr, stdout);
            fputc('\n', stdout);
            break;
        } else {
            close(serv_sock);
            serv_sock = -1;
        }
    }

    freeaddrinfo(serv_addr);

    return serv_sock;
}

int accept_tcp_connection(const int serv_sock) {
    struct sockaddr_storage client_addr;
    socklen_t client_addr_len = sizeof(client_addr);

    int client_sock = accept(serv_sock, (struct sockaddr *) &client_addr, &client_addr_len);
    if (client_sock < 0) {
        DieWithSystemMessage("accept() failed");
    }

    fputs("Handling client ", stdout);
    PrintSocketAddress((struct sockaddr *) &client_addr, stdout);
    fputc('\n', stdout);

    return client_sock;
}

void HandleTCPClient(const int client_sock) {
    char buffer[BUFSIZE];

    ssize_t num_bytes_rcvd = recv(client_sock, buffer, BUFSIZE, 0);
    if (num_bytes_rcvd < 0) {
        DieWithSystemMessage("recv() failed");
    }

    while (num_bytes_rcvd > 0) {
        ssize_t num_bytes_sent = send(client_sock, buffer, num_bytes_rcvd, 0);
        if (num_bytes_sent < 0) {
            DieWithSystemMessage("send() failed");
        } else if (num_bytes_sent != num_bytes_rcvd) {
            DieWithUserMessage("send()", "sent unexpected number of bytes");
        }

        num_bytes_rcvd = recv(client_sock, buffer, BUFSIZE, 0);
        if (num_bytes_rcvd < 0) {
            DieWithSystemMessage("recv() failed");
        }
    }

    close(client_sock);
}