修改parseARPPacket函数，解析ARP数据包 在代码文件中利用C++语言编写代码，实现ARP数据包的解析。 实验中使用到的ARP数据为0001080006040001eeeeeeeeeeeeac15e50b0000000000006463ae47/** * 利用C++语言编写代码 * 实现ARP数据包的解析 * 实验使用的ARP数据包内容为：0001080006040001eeeeeeeeeeeeac15e50b0000000000006463ae47 * */ #include <iostream> #include <iomanip> #include <sstream> #include <cstring> #include <fstream> #include <sys/stat.h> #include <arpa/inet.h> /** * @brief 将十六进制字符串转换为二进制数据 * * 该函数将一个十六进制字符串转换为二进制数据，并将结果存储在指定的缓冲区中。 * 每两个十六进制字符表示一个字节。 * * @param hexString 输入的十六进制字符串，长度必须为偶数。 * @param buffer 用于存储转换后的二进制数据的缓冲区。 * @param bufferSize 缓冲区的大小，必须至少为 `hexString.length() / 2`。 * */ void hexStringToBinary(const std::string& hexString, uint8_t* buffer, size_t bufferSize) { for (size_t i = 0; i < hexString.length(); i += 2) { std::string byteString = hexString.substr(i, 2); uint8_t byte = static_cast<uint8_t>(std::stoul(byteString, nullptr, 16)); buffer[i / 2] = byte; } } /** * @brief 检查文件是否存在 * * 该函数检查指定路径的文件是否存在。 * * @param filename 文件路径。 * @return true 文件存在。 * @return false 文件不存在。 */ bool fileExists(const std::string& filename) { struct stat buffer; return (stat(filename.c_str(), &buffer) == 0); } /** * @brief 解析ARP数据包 * * 该函数解析ARP数据包，并将解析结果输出到指定的文件中。 * * @param arpData ARP数据包的二进制数据。 * @param outputFile 输出文件的路径。 * * 此函数待补充完整。 */ void parseARPPacket(const uint8_t* arpData, const std::string& outputFile) { if (!fileExists(outputFile)) { std::ofstream createFile(outputFile); if (!createFile.is_open()) { std::cerr << "Failed to create output file: " << outputFile << std::endl; return; } createFile.close(); } std::ofstream outFile(outputFile, std::ios::out | std::ios::trunc); if (!outFile.is_open()) { std::cerr << "Failed to open output file: " << outputFile << std::endl; return; } // 解析ARP数据包 // 待实现***** // 硬件类型 uint16_t hardwareType = nto

### 解析ARP数据包并输出到文件 要实现 `parseARPPacket` 函数来解析 ARP 数据包并将结果保存至指定文件，可以通过以下方式完成： #### 1. **定义ARP数据包结构** ARP 数据包具有固定的格式，其头部由多个字段组成。以下是 ARP 头部的标准布局[^3]。 ```cpp struct ArpHeader { uint16_t hardwareType; // 硬件类型 (Ethernet = 0x0001) uint16_t protocolType; // 协议类型 (IPv4 = 0x0800) uint8_t hardwareSize; // 硬件地址长度 (MAC 地址 = 6 字节) uint8_t protocolSize; // 协议地址长度 (IP 地址 = 4 字节) uint16_t opcode; // 操作码 (请求=1, 应答=2) uint8_t senderMac[6]; // 发送方 MAC 地址 uint8_t senderIp[4]; // 发送方 IP 地址 uint8_t targetMac[6]; // 目标 MAC 地址 uint8_t targetIp[4]; // 目标 IP 地址 }; ``` 此结构体表示了一个标准的 ARP 报文头，其中包含了硬件类型、协议类型、操作码以及发送方和目标方的 MAC 和 IP 地址。 --- #### 2. **编写 parseARPPacket 函数** 通过读取十六进制字符串形式的数据包内容，将其转换为二进制数据，并提取 ARP 的各个字段信息。 ```cpp #include <iostream> #include <fstream> #include <iomanip> #include <string> // 定义 ARP 结构体 struct ArpHeader { uint16_t hardwareType; uint16_t protocolType; uint8_t hardwareSize; uint8_t protocolSize; uint16_t opcode; uint8_t senderMac[6]; uint8_t senderIp[4]; uint8_t targetMac[6]; uint8_t targetIp[4]; }; void parseARPPacket(const std::string& hexPacket, const std::string& outputFilename) { // 将十六进制字符串转换为字节数组 std::vector<uint8_t> packetBytes(hexPacket.length() / 2); for (size_t i = 0; i < hexPacket.length(); i += 2) { packetBytes[i / 2] = static_cast<uint8_t>(std::stoi(hexPacket.substr(i, 2), nullptr, 16)); } // 转换为 ARP Header if (packetBytes.size() >= sizeof(ArpHeader)) { const ArpHeader* arpHeader = reinterpret_cast<const ArpHeader*>(packetBytes.data()); // 打开文件流写入解析结果 std::ofstream outputFile(outputFilename); if (!outputFile.is_open()) { std::cerr << "无法打开文件：" << outputFilename << "\n"; return; } // 输出解析后的 ARP 数据包信息 outputFile << "Hardware Type: " << ntohs(arpHeader->hardwareType) << "\n"; // 网络序转主机序 outputFile << "Protocol Type: " << ntohs(arpHeader->protocolType) << "\n"; outputFile << "Hardware Size: " << static_cast<int>(arpHeader->hardwareSize) << "\n"; outputFile << "Protocol Size: " << static_cast<int>(arpHeader->protocolSize) << "\n"; outputFile << "Opcode: " << ntohs(arpHeader->opcode) << "\n"; outputFile << "Sender MAC Address: "; for (int i = 0; i < 6; ++i) { outputFile << std::setfill('0') << std::setw(2) << std::hex << static_cast<int>(arpHeader->senderMac[i]); if (i != 5) outputFile << ":"; } outputFile << "\n"; outputFile << "Sender IP Address: "; for (int i = 0; i < 4; ++i) { outputFile << static_cast<int>(arpHeader->senderIp[i]) << "."; } outputFile.seekp(-1, std::ios_base::end); // 移除最后一个 "." outputFile << "\n"; outputFile << "Target MAC Address: "; for (int i = 0; i < 6; ++i) { outputFile << std::setfill('0') << std::setw(2) << std::hex << static_cast<int>(arpHeader->targetMac[i]); if (i != 5) outputFile << ":"; } outputFile << "\n"; outputFile << "Target IP Address: "; for (int i = 0; i < 4; ++i) { outputFile << static_cast<int>(arpHeader->targetIp[i]) << "."; } outputFile.seekp(-1, std::ios_base::end); // 移除最后一个 "." outputFile << "\n"; outputFile.close(); } else { std::cerr << "数据包大小不足以构成完整的 ARP 报文\n"; } } ``` 上述代码实现了从十六进制字符串中解析 ARP 数据包的功能，并将解析结果存储到指定文件中。 --- #### 3. **调用示例** 假设有一个十六进制字符串表示的 ARP 数据包如下所示： ```cpp const char* hexData = "0001080006040001000c29aebf7e0acdfbfa0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000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