1 files changed, 129 insertions, 1 deletions
diff --git a/src/UDPClient/UDPClient.cpp b/src/UDPClient/UDPClient.cpp
index 640555f..75e81e1 100644
--- a/src/UDPClient/UDPClient.cpp
+++ b/src/UDPClient/UDPClient.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 Tobias Frust
+ * http://linux.m2osw.com/c-implementation-udp-clientserver
  *
  * UDPSender.cpp
  *
@@ -7,6 +7,134 @@
  *      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 <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){
+     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());
+     }
+ }
+
+ /** \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, size_t size){
+     return sendto(f_socket, msg, size, 0, f_addrinfo->ai_addr, f_addrinfo->ai_addrlen);
+ }