The C standard library provides the following functions to handle network protocols: socket(): Create a new network socket descriptor. connect(): Connect the socket to the remote address and port. send()/recv(): Send or receive data packets. listen(): Listens for incoming connections on the specified port. accept(): Accepts an incoming connection and creates a new socket descriptor.
A network protocol is a set of rules and conventions that control how computers communicate on a network. The C language provides rich functionality for developing network applications, including built-in functions for working with network protocols.
The C standard library provides the following functions to handle network protocols:
socket()
: Create new The network socket descriptor. connect()
: Connect the socket to the remote address and port. send()
/recv()
: Send or receive data packets. listen()
: Listens for incoming connections on the specified port. accept()
: Accepts an incoming connection and creates a new socket descriptor. The following example demonstrates how to use these functions to implement a simple TCP client-server protocol in a C application:
// 客户端代码 #include <iostream> #include <netdb.h> #include <sys/socket.h> int main() { struct sockaddr_in server_addr; memset(&server_addr, 0, sizeof(server_addr)); // 获取服务器的地址和端口号 char *host = "127.0.0.1"; int port = 8080; // 创建套接字 int sock = socket(AF_INET, SOCK_STREAM, 0); // 设置服务器地址 server_addr.sin_family = AF_INET; server_addr.sin_addr.s_addr = inet_addr(host); server_addr.sin_port = htons(port); // 连接到服务器 connect(sock, (struct sockaddr *) &server_addr, sizeof(server_addr)); // 发送数据到服务器 std::string message = "Hello from client!"; send(sock, message.c_str(), message.length(), 0); // 接收服务器的响应 char buffer[1024]; memset(buffer, 0, sizeof(buffer)); recv(sock, buffer, sizeof(buffer), 0); // 输出服务器响应 std::cout << "Received from server: " << buffer << std::endl; return 0; } // 服务器代码 #include <iostream> #include <netdb.h> #include <sys/socket.h> #include <unistd.h> int main() { struct sockaddr_in server_addr; memset(&server_addr, 0, sizeof(server_addr)); // 设置服务器的地址和端口号 char *host = "127.0.0.1"; int port = 8080; // 创建套接字 int sock = socket(AF_INET, SOCK_STREAM, 0); // 设置服务器地址 server_addr.sin_family = AF_INET; server_addr.sin_addr.s_addr = inet_addr(host); server_addr.sin_port = htons(port); // 绑定套接字到服务器地址 bind(sock, (struct sockaddr *) &server_addr, sizeof(server_addr)); // 开始侦听传入连接 listen(sock, 5); while (true) { struct sockaddr_in client_addr; memset(&client_addr, 0, sizeof(client_addr)); socklen_t client_addr_len = sizeof(client_addr); // 接受传入连接 int client_sock = accept(sock, (struct sockaddr *) &client_addr, &client_addr_len); // 从客户端接收数据 char buffer[1024]; memset(buffer, 0, sizeof(buffer)); recv(client_sock, buffer, sizeof(buffer), 0); // 发送响应到客户端 std::string message = "Hello from server!"; send(client_sock, message.c_str(), message.length(), 0); // 关闭客户端套接字 close(client_sock); } return 0; }
By calling C network programming functions, you can easily implement multiple network protocols. These functions provide a clean and efficient interface to handle the low-level details of network communication, allowing you to focus on your application logic.
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