我在客户端如何指定端口取和服务端通信-DPDK中文网

在客户端进行通信时，通常不需要显式地指定一个特定的本地端口，因为操作系统会自动分配一个可用的端口来建立连接。但如果您确实想要指定客户端使用的本地端口，可以使用 bind() 函数在调用 connect() 之前绑定一个特定的本地地址和端口。

示例代码

下面是如何在客户端代码中指定本地端口与服务器通信的示例：

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <fcntl.h>
#include <arpa/inet.h>

int setNonBlocking(int sockfd) {
    int flags = fcntl(sockfd, F_GETFL, 0);
    if (flags == -1) {
        std::cerr << "Failed to get socket flags!" << std::endl;
        return -1;
    }

    if (fcntl(sockfd, F_SETFL, flags | O_NONBLOCK) == -1) {
        std::cerr << "Failed to set non-blocking!" << std::endl;
        return -1;
    }
    
    return 0; // Success
}

void connectToPeer(const char* ip, int port, int localPort) {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        std::cerr << "Socket creation failed!" << std::endl;
        return;
    }

    struct sockaddr_in localAddr;
    memset(&localAddr, 0, sizeof(localAddr));
    localAddr.sin_family = AF_INET;
    localAddr.sin_port = htons(localPort); // 指定本地端口
    localAddr.sin_addr.s_addr = htonl(INADDR_ANY); // 使用任意可用地址

	// 在连接之前绑定本地地址和端口
	if (bind(sockfd, (struct sockaddr*)&localAddr, sizeof(localAddr)) == -1) {
		std::cerr << "Bind failed! Error: " << errno << std::endl;
		close(sockfd);
		return; 
	}

	struct sockaddr_in peerAddr;
	memset(&peerAddr, 0, sizeof(peerAddr));
	peerAddr.sin_family = AF_INET;
	peerAddr.sin_port = htons(port);
	
	if (inet_pton(AF_INET, ip, &peerAddr.sin_addr) <= 0) {
	    std::cerr << "Invalid address or address not supported" << std::endl;
	    close(sockfd);
	    return;
	}

	setNonBlocking(sockfd);

	if (connect(sockfd, (struct sockaddr*)&peerAddr, sizeof(peerAddr)) == -1) {
	    if (errno != EINPROGRESS) { // Check for error on connection
	        std::cerr << "Connection failed! Error: " << errno << std::endl; 
	        close(sockfd);
	        return; 
	    }
	}
	
	std::cout << "Connected successfully." << std::endl;

	close(sockfd); // Remember to close the socket when done.
}

int main() {
	const char* remoteIp = "192.168.8.36"; // Replace with the other client's IP address
	int remotePort = 5000; // The port you wish to connect to
	int localPort = 6000; // You want your client to use this specific port

	connectToPeer(remoteIp, remotePort, localPort);

	return 0;
}