6.2 UDP的传输特性 P112

ch06/uecho_client.c

@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+
+#define BUF_SIZE 30
+void error_handling(char *message);
+
+int main(int argc, char *argv[])
+{
+    int sock;
+    char message[BUF_SIZE];
+    int str_len;
+    socklen_t adr_sz;
+
+    struct sockaddr_in serv_adr, from_adr;
+    if (argc != 3)
+    {
+        printf("Usage : %s <IP> <port>\n", argv[0]);
+        exit(1);
+    }
+    //创建 UDP 套接字
+    sock = socket(PF_INET, SOCK_DGRAM, 0);
+    if (sock == -1)
+        error_handling("socket() error");
+
+    memset(&serv_adr, 0, sizeof(serv_adr));
+    serv_adr.sin_family = AF_INET;
+    serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
+    serv_adr.sin_port = htons(atoi(argv[2]));
+
+    while (1)
+    {
+        fputs("Insert message(q to quit): ", stdout);
+        fgets(message, sizeof(message), stdin);
+        if (!strcmp(message, "q\n") || !strcmp(message, "Q\n"))
+            break;
+        //向服务器传输数据,会自动给自己分配IP地址和端口号
+        sendto(sock, message, strlen(message), 0,
+               (struct sockaddr *)&serv_adr, sizeof(serv_adr));
+        adr_sz = sizeof(from_adr);
+        str_len = recvfrom(sock, message, BUF_SIZE, 0,
+                           (struct sockaddr *)&from_adr, &adr_sz);
+        message[str_len] = 0;
+        printf("Message from server: %s", message);
+    }
+    close(sock);
+    return 0;
+}
+
+void error_handling(char *message)
+{
+    fputs(message, stderr);
+    fputc('\n', stderr);
+    exit(1);
+}