http_redirector.cpp

#include "bibs.h"

#define PORT 80
#define IP_ADDR "127.0.0.1"
#define REMOTE_IP_ADDR "192.168.178.161"
#define BUFFER_SIZE 1024

void signalHandler(int sig) {
    cout << "Interrupt signal -- Programm stopped\n";
    exit(sig);
}

void sendRedirect(int client_socket, int port_number) {
    string response = 
        "HTTP/1.1 302 Found\r\n"
        "Location: http://192.168.178.161:" + std::to_string(port_number) + "/\r\n"
        "Content-Length: 0\r\n"
        "Connection: close\r\n"
        "\r\n";

    send(client_socket, response.c_str(), response.size(), 0);
    cout << "Send response to client " << client_socket << endl; 
}

void handleClient(int &client) {
    char buffer[BUFFER_SIZE];
    read(client, buffer, BUFFER_SIZE);

    const char* search_string = "GET";
    string message = buffer; 

    // filter the GET blabla.local/xyz to only get /xyz 
    if(message.find(search_string) != string::npos) {
        cout << search_string << " Found in HTTP msg\n";
        
        int request_cmd_leng = 4;
        int index = message.find(search_string) + request_cmd_leng;  
        string wanted_site = "";

        while (*(buffer + index) != ' ')
        {
            wanted_site = wanted_site + *(buffer + index);
            index++;
        }

        cout << "Want to visit site: " << wanted_site << endl;

        // redirect browser to spezified IP:PORT
        sendRedirect(client, 8096);
    }

    cout << "READ -- END -- closing thread... \n";
}

int main(void) {
    signal(SIGINT, signalHandler);

    // create TCP socket
    int listening_socket = socket(AF_INET, SOCK_STREAM, 0);
    // re-use socket --> no delay after restart
    int opt = 1;
    setsockopt(listening_socket, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
    
    // init server address
    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = inet_addr(IP_ADDR);
    serv_addr.sin_port = htons(PORT);
    bind(listening_socket, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

    // activate socket
    listen(listening_socket, 10);
    vector<int> clients;
    
    // main loop
    while (true)
    {
        // accecpt new client and add to vector
        struct sockaddr_in client_addr;
        unsigned int client_length = sizeof(client_addr);

        int client_socket = accept(listening_socket, (struct sockaddr*)&client_addr, &client_length);

        if(client_socket < 0)
            cout << "ERROR while connecting !!\n";
        else {
            cout << "Connection successful\n";
            clients.push_back(client_socket);
            thread client_thread(handleClient, ref(client_socket));
            client_thread.detach();
        }
    }

    return 0;
}