4.3 实现迭代服务端/客户端 P72

ch04/hello_client.c

@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+void error_handling(char *message);
+
+int main(int argc, char *argv[])
+{
+    int sock;
+    struct sockaddr_in serv_addr;
+    char message[30];
+    int str_len;
+
+    if (argc != 3)
+    {
+        printf("Usage : %s <IP> <port>\n", argv[0]);
+        exit(1);
+    }
+    //创建套接字，此时套接字并不马上分为服务端和客户端。如果紧接着调用 bind,listen 函数，将成为服务器套接字
+    //如果调用 connect 函数，将成为客户端套接字
+    sock = socket(PF_INET, SOCK_STREAM, 0);
+    if (sock == -1)
+        error_handling("socket() error");
+
+    memset(&serv_addr, 0, sizeof(serv_addr));
+    serv_addr.sin_family = AF_INET;
+    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
+    serv_addr.sin_port = htons(atoi(argv[2]));
+    //调用 connect 函数向服务器发送连接请求
+    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) == -1)
+        error_handling("connect() error!");
+
+    str_len = read(sock, message, sizeof(message) - 1);
+    if (str_len == -1)
+        error_handling("read() error!");
+
+    printf("Message from server : %s \n", message);
+    close(sock);
+    return 0;
+}
+
+void error_handling(char *message)
+{
+    fputs(message, stderr);
+    fputc('\n', stderr);
+    exit(1);
+}