First commit

ch1/TCPEchoClient4.c

@@ -0,0 +1,70 @@
+#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;
+}
+