mcpinger/network_utils.cpp

#include "network_utils.h"
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include "protocol_utils.h"

int sendData(int sockfd, const std::vector<unsigned char>& data) {
    ssize_t sent = send(sockfd, data.data(), data.size(), 0);
    if (sent < 0) {
        perror("Error sending data");
        return ERROR_SENDING_DATA;
    }
    return SUCCESS;
}

int receiveData(int sockfd, std::vector<unsigned char>& buffer) {
    buffer.resize(1024);
    ssize_t bytesReceived = recv(sockfd, buffer.data(), buffer.size(), 0);
    if (bytesReceived < 0) {
        perror("Error receiving data");
        return ERROR_RECEIVING_DATA;
    }
    buffer.resize(bytesReceived);
    return SUCCESS;
}

int pingMinecraftServer(const std::string& hostname, int port, const std::string& virtualHostname, int virtualPort, int protocolVersionIn, int nextStateIn) {
    struct addrinfo hints{}, *res, *result;
    int sockfd, err;

    (void)memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    err = getaddrinfo(hostname.c_str(), std::to_string(port).c_str(), &hints, &result);
    if (err != 0) {
        std::cerr << "Error resolving hostname: " << gai_strerror(err) << std::endl;
        return ERROR_RESOLVING_HOSTNAME;
    }

    for (res = result; res != nullptr; res = res->ai_next) {
        sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
        if (sockfd == -1) continue;

        if (connect(sockfd, res->ai_addr, res->ai_addrlen) != -1) break;

        (void)close(sockfd);
    }

    if (res == nullptr) {
        std::cerr << "Could not connect to any address" << std::endl;
        freeaddrinfo(result);
        return ERROR_CONNECTION_FAILED;
    }

    freeaddrinfo(result);

    // Handshake
    std::vector<unsigned char> packet;
    packet.push_back(0x00U); // Packet ID for handshake
    std::vector<unsigned char> protocolVersion = encodeVarint(protocolVersionIn);
    std::vector<unsigned char> serverAddress = encodeString(virtualHostname);
    std::vector<unsigned char> serverPort = {static_cast<unsigned char>((virtualPort >> 8) & 0xFFU), static_cast<unsigned char>(virtualPort & 0xFFU) };
    std::vector<unsigned char> nextState = encodeVarint(nextStateIn);

    (void)packet.insert(packet.end(), protocolVersion.begin(), protocolVersion.end());
    (void)packet.insert(packet.end(), serverAddress.begin(), serverAddress.end());
    (void)packet.insert(packet.end(), serverPort.begin(), serverPort.end());
    (void)packet.insert(packet.end(), nextState.begin(), nextState.end());

    std::vector<unsigned char> handshakeLength = encodeVarint(packet.size());
    (void)packet.insert(packet.begin(), handshakeLength.begin(), handshakeLength.end());

    if (sendData(sockfd, packet) != SUCCESS) {
        (void)close(sockfd);
        return ERROR_SENDING_DATA;
    }

    // Status request
    std::vector<unsigned char> statusRequest = {0x01U, 0x00U}; // Packet length and Packet ID for status request
    if (sendData(sockfd, statusRequest) != SUCCESS) {
        (void)close(sockfd);
        return ERROR_SENDING_DATA;
    }

    // Read status response
    std::vector<unsigned char> response;
    if (receiveData(sockfd, response) != SUCCESS) {
        (void)close(sockfd);
        return ERROR_RECEIVING_DATA;
    }

    // Extract JSON string (assuming it starts from the position of the first '{' found in the response)
    auto pos = std::find(response.begin(), response.end(), '{');
    if (pos != response.end()) {
        std::string json(pos, response.end());
        std::cout << json << std::endl;
    } else {
        std::cerr << "Failed to find JSON response in server data." << std::endl;
    }

    (void)close(sockfd);
    return SUCCESS;
}