Improved logging and added code to handle failed dns lookup of cached dns record.

[bpdyndnsd] / src / iphelper.cpp

/** @file
 * @brief IPHelper class implementation. This class represents a Helper to get the actual IP.
 *
 *
 *
 * @copyright Intra2net AG
 * @license GPLv2
*/

#include "iphelper.h"
#include <boost/asio.hpp>
#include <boost/regex.hpp>

using namespace std;

namespace net = boost::asio;

/**
 * Default constructor.
 */
IPHelper::IPHelper()
    : Hostname("")
    , WebcheckIpUrl("")
    , WebcheckIpUrlAlt("")
    , UseIPv6(false)
    , Log(new Logger)
{
}


/**
 * Constructor.
 */
IPHelper::IPHelper(const Logger::Ptr _log, const string& _webcheck_url, const string& _webcheck_url_alt, const bool _use_ipv6)
    : Hostname("")
{
    Log = _log;
    WebcheckIpUrl = _webcheck_url;
    WebcheckIpUrlAlt = _webcheck_url_alt;
    UseIPv6 = _use_ipv6;
    Hostname = net::ip::host_name();

    Log->print_hostname(Hostname);
}


/**
 * Default destructor
 */
IPHelper::~IPHelper()
{
}


/**
 * Get the actual IP of this host through a conventional DNS query or through a IP webcheck URL if configured so.
 * @return A string representation of the actual IP in dotted format or an empty string if something went wrong.
 */
string IPHelper::get_actual_ip() const
{
    string ip;
    if ( WebcheckIpUrl.empty() )
    {
        ip = dns_query("");
    }
    else
    {
        ip = webcheck_ip();
    }

    // TODO IF IP is local, then return ""

    return ip;
}


/**
 * Get the actual IP of this host through a DNS query.
 * @param _hostname The hostname for the dns lookup, if empty string, then perform a dns lookup to the local hostname.
 * @return A string representation of the actual IP in dotted format or an empty string if something went wrong.
 */
string IPHelper::dns_query(const string& _hostname) const
{
    string ip_addr_v4;
    string ip_addr_v6;

    string hostname = Hostname;
    if ( !_hostname.empty() )
        hostname = _hostname;

    try
    {
        // BOOST asio isn't the simplest way to perform a DNS lookup, but it works just fine.
        net::io_service io_service;
        net::ip::tcp::resolver resolver(io_service);
        net::ip::tcp::resolver::query query(hostname, "0");
        net::ip::tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
        net::ip::tcp::resolver::iterator end;
        while(endpoint_iterator != end)
        {
            net::ip::tcp::endpoint endpoint = endpoint_iterator->endpoint();    // this ends up in a compiler warning: cc1plus: warning: dereferencing pointer 'pretmp.37188' does break strict-aliasing rules
            net::ip::address ip = endpoint.address();                           // but why?
            if ( ip.is_v4() )
                ip_addr_v4 = ip.to_string();
            else if ( ip.is_v6() )
                ip_addr_v6 = ip.to_string();
            Log->print_own_ipv4(ip_addr_v4, hostname);
            if ( UseIPv6 == true )
                Log->print_own_ipv6(ip_addr_v6, hostname);
            endpoint_iterator++;
        }
        io_service.reset();
    }
    catch(exception& e)
    {
        Log->print_error_hostname_to_ip(e.what(),hostname);
        return "";
    }

    if ( (UseIPv6 == true) && (ip_addr_v6 != "") )
        return ip_addr_v6;

    return ip_addr_v4;
}


/**
 * Get the actual IP of this host through a IP webcheck URL.
 * @return A string representation of the actual IP in dotted format or an empty string if something went wrong.
 */
string IPHelper::webcheck_ip() const
{
    string ip_addr = "";

    // Init CURL buffers
    string curl_writedata_buff;
    char curl_err_buff[CURL_ERROR_SIZE];
    int curl_err_code=1;

    // Init URL List
    list<string> url_list;
    url_list.push_back(WebcheckIpUrl);
    url_list.push_back(WebcheckIpUrlAlt);
    string actual_url;

    // Init CURL
    CURL * curl_easy_handle = init_curl(curl_writedata_buff,curl_err_buff);

    // If perform_curl_operation returns a connection problem indicating return code, try the next ip webcheck url if there is one.
    while ( (curl_err_code == 1) && (url_list.size() != 0) && (url_list.front() != "") )
    {
        // Set URL
        actual_url = url_list.front();
        url_list.pop_front();
        set_curl_url(curl_easy_handle,actual_url);

        // Perform curl operation
        curl_err_code = perform_curl_operation(curl_easy_handle, curl_err_buff, actual_url);
    }

    // Cleanup CURL handle
    curl_easy_cleanup(curl_easy_handle);

    // If curl_err_code is not 0, the ip couldn't be determined through any configured webcheck url.
    if ( curl_err_code != 0 )
    {
        Log->print_webcheck_no_ip();
        // error handling
        return ip_addr;
    }

    Log->print_received_curl_data(curl_writedata_buff);

    ip_addr = parse_ip(curl_writedata_buff);

    return ip_addr;
}


/**
 * Tries to find a valid IPv4 Address in dottet format in a given string and returns the IP-Address found.
 * @param data The string data to search in for a valid IPv4-Address.
 * @return The IP Address found or an empty string.
 */
string IPHelper::parse_ip(const string& data) const
{
    string ip = "";

    // regex for valid ip address
    boost::regex expr("([0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3})");

    boost::smatch matches;

    if ( boost::regex_search(data,matches,expr) )
    {
        ip = matches[1];
        Log->print_regex_found_ip(ip);
    }
    else
    {
        Log->print_regex_ip_not_found(data);
    }

    return ip;
}


/**
 * Performs the curl operation.
 * @param curl_easy_handle The initialized and configured curl handle.
 * @param curl_err_buff The pointer to the curl error buffer to get error messages from.
 * @param actual_url The actual configured URL.
 * @return 0 if all is fine, 1 if an connection problem to the configured url occurs, -1 on other errors.
 */
int IPHelper::perform_curl_operation(CURL * curl_easy_handle, char* curl_err_buff, const string& actual_url) const
{
    int curl_err_code;
    if ( (curl_err_code = curl_easy_perform(curl_easy_handle) ) != 0 )
    {
        // CURL error occured
        if ( (curl_err_code == CURLE_COULDNT_CONNECT) || (curl_err_code == CURLE_OPERATION_TIMEOUTED) || (curl_err_code == CURLE_COULDNT_RESOLVE_HOST) )
        {
            // In case of connection problems we should return 1, that the fallback url will be used.
            Log->print_webcheck_url_connection_problem(curl_err_buff, actual_url);
            return 1;
        }
        else
        {
            // other error
            Log->print_webcheck_error(curl_err_buff, actual_url);
            return -1;
        }
    }
    // Operation performed without any problems
    return 0;
}


/**
 * Sets a url to the easy curl handle
 * @param curl_easy_handle The easy curl handle to set the url for.
 * @param url The url to set.
 */
void IPHelper::set_curl_url(CURL * curl_easy_handle, const string& url) const
{
    curl_easy_setopt(curl_easy_handle,CURLOPT_URL,url.c_str());
}


/**
 * Initialized curl easy handle with a few options.
 * @param curl_writedata_buff Reference to a string wich will be filled with the curl result
 * @param curl_err_buff A pointer to an char array which will be filled with error message.
 * @return A pointer to the easy curl handle.
 */
CURL * IPHelper::init_curl(string& curl_writedata_buff,char* curl_err_buff) const
{
    CURL *curl_easy_handle = curl_easy_init();

    curl_easy_setopt(curl_easy_handle,CURLOPT_NOPROGRESS,1);
    curl_easy_setopt(curl_easy_handle,CURLOPT_CONNECTTIMEOUT,5);
    curl_easy_setopt(curl_easy_handle,CURLOPT_TIMEOUT,10);
    curl_easy_setopt(curl_easy_handle,CURLOPT_BUFFERSIZE,1024);
    curl_easy_setopt(curl_easy_handle,CURLOPT_ERRORBUFFER,curl_err_buff);
    curl_easy_setopt(curl_easy_handle,CURLOPT_WRITEFUNCTION,http_receive);
    curl_easy_setopt(curl_easy_handle,CURLOPT_WRITEDATA,&curl_writedata_buff);

    return curl_easy_handle;
}


/**
 * Callback Function is called every time CURL is receiving data from HTTPS-Server and will copy all received Data to the given stream pointer
 * @param inBuffer Pointer to input.
 * @param size How many mem blocks are received
 * @param nmemb size of each memblock
 * @param outBuffer Pointer to output stream.
 * @return The size received.
 */
int IPHelper::http_receive( char *inBuffer, size_t size, size_t nmemb, string *outBuffer )
{
    outBuffer->append(inBuffer);
    return (size*nmemb);
}