Linux网络编程——UDP文件传输

客户端：

#include <iostream>
#include <fstream>
#include <cstring>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>

#define BUFFER_SIZE 1024

int main() {
    std::string filename = "file.txt";
    std::ifstream inputFile(filename, std::ios::binary);
    
    if (!inputFile) {
        std::cerr << "无法打开文件" << std::endl;
        return -1;
    }
    
    // 获取文件大小
    inputFile.seekg(0, std::ios::end);
    int fileSize = inputFile.tellg();
    inputFile.seekg(0, std::ios::beg);
    
    // 创建UDP套接字
    int clientSocket;
    struct sockaddr_in serverAddress;
    
    clientSocket = socket(AF_INET, SOCK_DGRAM, 0);
    if (clientSocket < 0) {
        std::cerr << "无法创建套接字" << std::endl;
        return -1;
    }
    
    // 设置服务端地址和端口号
    serverAddress.sin_family = AF_INET;
    serverAddress.sin_port = htons(8888);
    serverAddress.sin_addr.s_addr = inet_addr("127.0.0.1");
    
    char buffer[BUFFER_SIZE];
    int bytesRead;
    int totalBytesSent = 0;
    
    while (!inputFile.eof()) {
        // 从文件读取数据
        inputFile.read(buffer, BUFFER_SIZE);
        bytesRead = inputFile.gcount();
        
        // 发送数据块给服务端
        ssize_t bytesSent = sendto(clientSocket, buffer, bytesRead, 0, (struct sockaddr*)&serverAddress, sizeof(serverAddress));
        if (bytesSent < 0) {
            std::cerr << "发送数据失败" << std::endl;
            return -1;
        }
        
        totalBytesSent += bytesSent;
        
        std::cout << "已发送 " << totalBytesSent << " 字节 / " << fileSize << " 字节" << std::endl;
    }
    
    // 关闭文件
    inputFile.close();
    
    // 关闭UDP套接字
    close(clientSocket);
    
    return 0;
}

在这个示例代码中，我们打开名为file.txt的文件，并使用std::ifstream来读取文件内容。然后，我们获取文件的大小，以便在传输过程中进行跟踪。

接下来，我们创建UDP套接字并设置服务端的地址和端口号。然后，我们使用一个循环来读取文件内容，并将其分割成大小为BUFFER_SIZE的数据块。每个数据块都被发送到服务端，并使用sendto()函数返回的字节数来跟踪已发送的总字节数。

服务端：

#include <iostream>
#include <fstream>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>

#define BUFFER_SIZE 1024

int main() {
    std::string filename = "received_file.txt";
    std::ofstream outputFile(filename, std::ios::binary);
    
    if (!outputFile) {
        std::cerr << "无法创建文件" << std::endl;
        return -1;
    }
    
    // 创建UDP套接字
    int serverSocket;
    struct sockaddr_in serverAddress, clientAddress;
    
    serverSocket = socket(AF_INET, SOCK_DGRAM, 0);
    if (serverSocket < 0) {
        std::cerr << "无法创建套接字" << std::endl;
        return -1;
    }
    
    // 设置服务端地址和端口号
    serverAddress.sin_family = AF_INET;
    serverAddress.sin_port = htons(8888);
    serverAddress.sin_addr.s_addr = INADDR_ANY;
    
    // 将套接字绑定到服务端地址和端口号
    if (bind(serverSocket, (struct sockaddr*)&serverAddress, sizeof(serverAddress)) < 0) {
        std::cerr << "绑定套接字失败" << std::endl;
        return -1;
    }
    
    char buffer[BUFFER_SIZE];
    int bytesReceived;
    int totalBytesReceived = 0;
    
    while (true) {
        socklen_t clientAddressLength = sizeof(clientAddress);
        
        // 接收来自客户端的数据块
        bytesReceived = recvfrom(serverSocket, buffer, BUFFER_SIZE, 0, (struct sockaddr*)&clientAddress, &clientAddressLength);
        if (bytesReceived < 0) {
            std::cerr << "接收数据失败" << std::endl;
            return -1;
        }
        
        // 将数据块写入文件
        outputFile.write(buffer, bytesReceived);
        
        totalBytesReceived += bytesReceived;
        
        std::cout << "已接收 " << totalBytesReceived << " 字节" << std::endl;
        
        // 发送确认响应给客户端
        std::string response = "确认收到";
        sendto(serverSocket, response.c_str(), response.length(), 0, (struct sockaddr*)&clientAddress, clientAddressLength);
        
        // 接收完所有数据后退出循环
        if (bytesReceived < BUFFER_SIZE) {
            break;
        }
    }
    
    // 关闭文件
    outputFile.close();
    
    // 关闭UDP套接字
    close(serverSocket);
    
    return 0;
}