/*
 * http://linux.m2osw.com/c-implementation-udp-clientserver
 *
 * UDPSender.cpp
 *
 *  Created on: 29.06.2016
 *      Author: Tobias Frust
 */

 // ========================= CLIENT =========================

 /** \brief Initialize a UDP client object.
  *
  * This function initializes the UDP client object using the address and the
  * port as specified.
  *
  * The port is expected to be a host side port number (i.e. 59200).
  *
  * The \p addr parameter is a textual address. It may be an IPv4 or IPv6
  * address and it can represent a host name or an address defined with
  * just numbers. If the address cannot be resolved then an error occurs
  * and constructor throws.
  *
  * \note
  * The socket is open in this process. If you fork() or exec() then the
  * socket will be closed by the operating system.
  *
  * \warning
  * We only make use of the first address found by getaddrinfo(). All
  * the other addresses are ignored.
  *
  * \exception udp_client_server_runtime_error
  * The server could not be initialized properly. Either the address cannot be
  * resolved, the port is incompatible or not available, or the socket could
  * not be created.
  *
  * \param[in] addr  The address to convert to a numeric IP.
  * \param[in] port  The port number.
  */

#include "UDPClient.h"

#include <stdio.h>
#include <string.h>
#include <unistd.h>

#ifndef SOCK_CLOEXEC
#define SOCK_CLOEXEC 0
#endif

 UDPClient::UDPClient(const std::string& addr, int port)
     : f_port(port)
     , f_addr(addr){
     printf("Creating client %d\n", f_port);
     char decimal_port[16];
     snprintf(decimal_port, sizeof(decimal_port), "%d", f_port);
     decimal_port[sizeof(decimal_port) / sizeof(decimal_port[0]) - 1] = '\0';
     struct addrinfo hints;
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = AF_UNSPEC;
     hints.ai_socktype = SOCK_DGRAM;
     hints.ai_protocol = IPPROTO_UDP;
     int r(getaddrinfo(addr.c_str(), decimal_port, &hints, &f_addrinfo));
     if(r != 0 || f_addrinfo == NULL)
     {
         throw udp_client_server_runtime_error(("invalid address or port: \"" + addr + ":" + decimal_port + "\"").c_str());
     }

     f_socket = socket(f_addrinfo->ai_family, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
     if(f_socket == -1)
     {
         freeaddrinfo(f_addrinfo);
         throw udp_client_server_runtime_error(("could not create socket for: \"" + addr + ":" + decimal_port + "\"").c_str());
     }
 
     if (connect(f_socket, f_addrinfo->ai_addr, f_addrinfo->ai_addrlen))
     {
	close(f_socket);
        freeaddrinfo(f_addrinfo);
        throw udp_client_server_runtime_error(("could not connect socket for: \"" + addr + ":" + decimal_port + "\"").c_str());
     }
     
     printf("Created client %d\n", f_port);
 }

 /** \brief Clean up the UDP client object.
  *
  * This function frees the address information structure and close the socket
  * before returning.
  */
 UDPClient::~UDPClient()
 {
     freeaddrinfo(f_addrinfo);
     close(f_socket);
 }

 /** \brief Retrieve a copy of the socket identifier.
  *
  * This function return the socket identifier as returned by the socket()
  * function. This can be used to change some flags.
  *
  * \return The socket used by this UDP client.
  */
 int UDPClient::get_socket() const {
     return f_socket;
 }

 /** \brief Retrieve the port used by this UDP client.
  *
  * This function returns the port used by this UDP client. The port is
  * defined as an integer, host side.
  *
  * \return The port as expected in a host integer.
  */
 int UDPClient::get_port() const {
     return f_port;
 }

 /** \brief Retrieve a copy of the address.
  *
  * This function returns a copy of the address as it was specified in the
  * constructor. This does not return a canonalized version of the address.
  *
  * The address cannot be modified. If you need to send data on a different
  * address, create a new UDP client.
  *
  * \return A string with a copy of the constructor input address.
  */
 std::string UDPClient::get_addr() const {
     return f_addr;
 }

 /** \brief Send a message through this UDP client.
  *
  * This function sends \p msg through the UDP client socket. The function
  * cannot be used to change the destination as it was defined when creating
  * the udp_client object.
  *
  * The size must be small enough for the message to fit. In most cases we
  * use these in Snap! to send very small signals (i.e. 4 bytes commands.)
  * Any data we would want to share remains in the Cassandra database so
  * that way we can avoid losing it because of a UDP message.
  *
  * \param[in] msg  The message to send.
  * \param[in] size  The number of bytes representing this message.
  *
  * \return -1 if an error occurs, otherwise the number of bytes sent. errno
  * is set accordingly on error.
  */
 int UDPClient::send(const char *msg, std::size_t size){
     return sendto(f_socket, msg, size, 0, f_addrinfo->ai_addr, f_addrinfo->ai_addrlen);
 }

 int UDPClient::msend(int n, struct mmsghdr *msg){
     return sendmmsg(f_socket, msg, n, 0);
 }