UDPSocket.cpp

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#include "UDPSocket.h"
#include "TempFailure.h"

#include <sys/socket.h>
#include <arpa/inet.h>
#include <poll.h>

using namespace NET;

namespace {

void setBroadcast( int socket)
{
    // If this fails, we'll hear about it when we try to send. This will allow
    // systems that cannot broadcast to continue if they don't plan to broadcast
    int broadcastPermission = 1;
    setsockopt( socket,
            SOL_SOCKET,
            SO_BROADCAST,
            (raw_type*)&broadcastPermission,
            sizeof(broadcastPermission));
}

int groupAction( int socket, const std::string& multicastGroup, int action)
{
    struct ip_mreq multicastRequest;
    multicastRequest.imr_multiaddr.s_addr = inet_addr( multicastGroup.c_str());
    multicastRequest.imr_interface.s_addr = htonl(INADDR_ANY);

    return( setsockopt( socket,
                IPPROTO_IP,
                action,
                (raw_type*)&multicastRequest,
                sizeof(multicastRequest)));
}

} // namespace

UDPSocket::UDPSocket()
: InternetSocket( DATAGRAM, IPPROTO_UDP)
{
    setBroadcast(m_socket);
}

void UDPSocket::sendTo( const void* buffer, size_t len, const std::string& foreignAddress, unsigned short foreignPort)
{
    sockaddr_in destAddr;
    fillAddress( foreignAddress, foreignPort, destAddr);

    int sent = TEMP_FAILURE_RETRY (::sendto( m_socket, (const raw_type*)buffer, len, 0, (sockaddr*)&destAddr, sizeof(destAddr)));

    // Write out the whole buffer as a single message
    if( sent != (int)len)
        throw SocketException("Send failed (sendto)");
}

int UDPSocket::receiveFrom( void* buffer, size_t len, std::string& sourceAddress, unsigned short& sourcePort)
{
    sockaddr_in clientAddr;
    socklen_t addrLen = sizeof(clientAddr);

    int ret = TEMP_FAILURE_RETRY (::recvfrom( m_socket, (raw_type*)buffer, len, 0, (sockaddr*)&clientAddr, &addrLen));
    if( ret < 0)
        throw SocketException("Receive failed (recvfrom)");

    sourceAddress = inet_ntoa( clientAddr.sin_addr);
    sourcePort = ntohs( clientAddr.sin_port);

    return ret;
}

int UDPSocket::timedReceiveFrom( void* buffer, size_t len, std::string& sourceAddress, unsigned short& sourcePort, int timeout)
{
    struct pollfd poll;
    poll.fd = m_socket;
    poll.events = POLLIN | POLLPRI | POLLRDHUP;

    int ret = TEMP_FAILURE_RETRY (::poll( &poll, 1, timeout));

    if( ret == 0) return 0;
    if( ret < 0)  throw SocketException("Receive failed (poll)");

    if( poll.revents & POLLRDHUP)
        m_peerDisconnected = true;

    if( poll.revents & POLLIN || poll.revents & POLLPRI)
        return receiveFrom( buffer, len, sourceAddress, sourcePort);

    return 0;
}

void UDPSocket::setMulticastTTL( unsigned char multicastTTL)
{
    if( setsockopt( m_socket,
                    IPPROTO_IP,
                    IP_MULTICAST_TTL,
                    (raw_type*)&multicastTTL,
                    sizeof(multicastTTL)) < 0)
        throw SocketException("Multicast set TTL failed (setsockopt)");
}

void UDPSocket::joinGroup( const std::string& multicastGroup)
{
    if( groupAction( m_socket, multicastGroup, IP_ADD_MEMBERSHIP) < 0)
        throw SocketException("Multicast group join failed (setsockopt)");
}

void UDPSocket::leaveGroup( const std::string& multicastGroup)
{
    if( groupAction( m_socket, multicastGroup, IP_DROP_MEMBERSHIP) < 0)
        throw SocketException("Multicast group leave failed (setsockopt)");
}