TCP/IP网络编程 第十四章:多播与广播

**TCP/IP网络编程**

**第十四章:多播与广播**

在前面的章节中，我们已经学习了如何使用TCP/IP协议栈进行网络通信。然而，在某些情况下，单播通信可能不足够有效。在这种情况下，多播和广播通信就变得非常重要。

**1. 多播通信**

多播通信是一种特殊类型的通信方式，它允许一个源地址向多个目的地址发送数据包。多播通信通常用于在局域网中传输相同的信息给多台机器。

在TCP/IP协议栈中，多播通信使用IP多播地址来实现。IP多播地址是特殊类型的IP地址，它们以224.0.0.0至239.255.255.255为范围。

下面是一个简单的例子，演示了如何使用C语言编写一个多播服务器和客户端：

**多播服务器代码**

c#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define MULTICAST_ADDR "224.0.0.1"
#define PORT1234int main() {
 int sock = socket(AF_INET, SOCK_DGRAM,0);
 if (sock < 0) {
 perror("socket");
 exit(1);
 }

 struct sockaddr_in server_addr;
 server_addr.sin_family = AF_INET;
 server_addr.sin_port = htons(PORT);
 inet_pton(AF_INET, MULTICAST_ADDR, &server_addr.sin_addr);

 char buffer[1024];
 while (1) {
 printf("请输入要发送的信息：");
 fgets(buffer,1024, stdin);
 sendto(sock, buffer, strlen(buffer),0, (struct sockaddr*)&server_addr, sizeof(server_addr));
 }

 return0;
}

c#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define MULTICAST_ADDR "224.0.0.1"
#define PORT1234int main() {
 int sock = socket(AF_INET, SOCK_DGRAM,0);
 if (sock < 0) {
 perror("socket");
 exit(1);
 }

 struct sockaddr_in client_addr;
 client_addr.sin_family = AF_INET;
 client_addr.sin_port = htons(PORT);
 inet_pton(AF_INET, MULTICAST_ADDR, &client_addr.sin_addr);

 char buffer[1024];
 while (1) {
 recvfrom(sock, buffer,1024,0, (struct sockaddr*)&client_addr, sizeof(client_addr));
 printf("收到信息：%s
", buffer);
 }

 return0;
}

c#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define BROADCAST_ADDR "255.255.255.255"
#define PORT1234int main() {
 int sock = socket(AF_INET, SOCK_DGRAM,0);
 if (sock < 0) {
 perror("socket");
 exit(1);
 }

 struct sockaddr_in server_addr;
 server_addr.sin_family = AF_INET;
 server_addr.sin_port = htons(PORT);
 inet_pton(AF_INET, BROADCAST_ADDR, &server_addr.sin_addr);

 char buffer[1024];
 while (1) {
 printf("请输入要发送的信息：");
 fgets(buffer,1024, stdin);
 sendto(sock, buffer, strlen(buffer),0, (struct sockaddr*)&server_addr, sizeof(server_addr));
 }

 return0;
}

c#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define BROADCAST_ADDR "255.255.255.255"
#define PORT1234int main() {
 int sock = socket(AF_INET, SOCK_DGRAM,0);
 if (sock < 0) {
 perror("socket");
 exit(1);
 }

 struct sockaddr_in client_addr;
 client_addr.sin_family = AF_INET;
 client_addr.sin_port = htons(PORT);
 inet_pton(AF_INET, BROADCAST_ADDR, &client_addr.sin_addr);

 char buffer[1024];
 while (1) {
 recvfrom(sock, buffer,1024,0, (struct sockaddr*)&client_addr, sizeof(client_addr));
 printf("收到信息：%s
", buffer);
 }

 return0;
}