第 6 章 基于 UDP 的服务端/客户端

#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; //多余变量 struct sockaddr_in serv_adr, from_adr; //不需要 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])); connect(sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr)); 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)); */ write(sock, message, strlen(message)); /* adr_sz = sizeof(from_adr); str_len = recvfrom(sock, message, BUF_SIZE, 0, (struct sockaddr *)&from_adr, &adr_sz); */ str_len = read(sock, message, sizeof(message) - 1); 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); }