tcp-ip-sockets-in-c/ch2/TCPEchoClient4.c

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

#include "Practical.h"

int main(int argc, char **argv) {
    if (argc < 3 || argc > 4) {
        DieWithUserMessage("Parameter(s)", "<Server Address> <Echo Word> [<Server Port>]");
    }

    const char *server_ip = argv[1];
    const char *echo_str = argv[2];
    const in_port_t server_port = (argc == 4) ? atoi(argv[3]) : 7; // 7: common echo port

    const int sock = socket(AF_INET, SOCK_STREAM, proto_get_num("tcp"));
    if (sock < 0) {
        DieWithSystemMessage("socket() failed");
    }

    struct sockaddr_in server_addr = {0};
    server_addr.sin_family = AF_INET;
    int ret_val = inet_pton(AF_INET, server_ip, &server_addr.sin_addr.s_addr);
    if (ret_val == 0) {
        DieWithUserMessage("inet_pton() failed", "invalid address string");
    } else if (ret_val < 0) {
        DieWithSystemMessage("inet_pton() failed");
    }
    server_addr.sin_port = htons(server_port);

    if (connect(sock, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0) {
        DieWithSystemMessage("connect() failed");
    }

    const size_t echo_str_len = strlen(echo_str);

    ssize_t num_bytes = send(sock, echo_str, echo_str_len, 0);
    if (num_bytes < 0) {
        DieWithSystemMessage("send() failed");
    } else if ((size_t) num_bytes != echo_str_len) {
        DieWithUserMessage("send()", "sent unexpected number of bytes");
    }
    
    unsigned int total_bytes_rcvd = 0;
    fputs("Received: ", stdout);
    while (total_bytes_rcvd < echo_str_len) {
        char buffer[BUFSIZE];
        num_bytes = recv(sock, buffer, BUFSIZE - 1, 0);
        if (num_bytes < 0) {
            DieWithSystemMessage("recv() failed");
        } else if (num_bytes == 0) {
            DieWithUserMessage("recv()", "connection closed prematurely");
        }
        total_bytes_rcvd += num_bytes;
        buffer[num_bytes] = '\0';
        fputs(buffer, stdout);
    }

    fputc('\n', stdout);

    close(sock);

    return 0;
}