// **************************************************************************
/** @namespace Dim

@brief Namespace to host some global Dim helper functions

*/
// **************************************************************************
#include "Dim.h"

#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#include <iostream>

using namespace std;

// --------------------------------------------------------------------------
//
//! Tries to determine the local IP address with which we will connect
//! to the DIM dns.
//!
//! @param dns
//!     Address of the Dim-dns
//!
//! @returns
//!     The IP Address through which the connection to the DNS will
//!     take place.
//!
string Dim::GetLocalIp(const string &dns)
{
    struct addrinfo hints, *servinfo, *p;

    memset(&hints, 0, sizeof hints);
    hints.ai_family   = AF_INET; //AF_UNSPEC; // use AF_INET6 to force IPv6
    hints.ai_socktype = SOCK_STREAM;

    int rv;
    if ((rv = getaddrinfo(dns.c_str(), NULL, &hints, &servinfo)) != 0)
    {
        cout << "WARNING - getaddrinfo: " << gai_strerror(rv) << endl;
        return dns;
    }

    // loop through all the results and connect to the first we can
    for (p=servinfo; p; p=p->ai_next)
    {
        const int sock = socket(AF_INET, SOCK_DGRAM, 0);
        if (sock==-1)
            continue;

        if (connect(sock, p->ai_addr, p->ai_addrlen)==-1)
        {
            cout << "WARNING - connect: " << strerror(errno) << endl;
            close(sock);
            continue;
        }

        sockaddr_in name;
        socklen_t namelen = sizeof(name);
        if (getsockname(sock, (sockaddr*)&name, &namelen)==-1)
        {
            cout << "WARNING - getsockname: " << strerror(errno) << endl;
            close(sock);
            continue;
        }

        char buffer[16];
        if (!inet_ntop(AF_INET, &name.sin_addr, buffer, 16))
        {
            cout << "WARNING - inet_ntop: " << strerror(errno) << endl;
            close(sock);
            continue;
        }

        close(sock);

        freeaddrinfo(servinfo); // all done with this structure

        cout << "DIM_HOST_NODE=" << buffer << endl;
        return buffer;
    }

    freeaddrinfo(servinfo); // all done with this structure

    return dns;
}

// --------------------------------------------------------------------------
//
//! Set the environment variable DIM_DNS_NODE to the given string and
//! DIM_HOST_NODE to the IP-address through which this machine connects
//! to the dns.
//!
//! @param dns
//!     Address of the Dim-dns
//!
void Dim::Setup(const std::string &dns)
{
    setenv("DIM_DNS_NODE",  dns.c_str(),             1);
    setenv("DIM_HOST_NODE", GetLocalIp(dns).c_str(), 1);
}