Added an example for demonstrating the usage of curl multi interface
with boost::asio in c++

---
 docs/examples/Makefile.inc  |    2 +-
 docs/examples/asiohiper.cpp |  467 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 468 insertions(+), 1 deletion(-)
 create mode 100644 docs/examples/asiohiper.cpp
diff --git a/docs/examples/Makefile.inc b/docs/examples/Makefile.inc
index 2b31f86..e1f24cb 100644
--- a/docs/examples/Makefile.inc
+++ b/docs/examples/Makefile.inc
@@ -12,4 +12,4 @@ check_PROGRAMS = 10-at-a-time anyauthput cookie_interface debug fileupload \
 COMPLICATED_EXAMPLES = curlgtk.c curlx.c htmltitle.cc cacertinmem.c	   \
   ftpuploadresume.c ghiper.c hiperfifo.c htmltidy.c multithread.c	   \
   opensslthreadlock.c sampleconv.c synctime.c threaded-ssl.c evhiperfifo.c \
-  smooth-gtk-thread.c version-check.pl href_extractor.c
+  smooth-gtk-thread.c version-check.pl href_extractor.c asiohiper.cpp
diff --git a/docs/examples/asiohiper.cpp b/docs/examples/asiohiper.cpp
new file mode 100644
index 0000000..1ea3502
--- /dev/null
+++ b/docs/examples/asiohiper.cpp
@@ -0,0 +1,467 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2012, Daniel Stenberg, <daniel_at_haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+/*
+ * file: asiohiper.cpp
+ * Example program to demonstrate the use of multi socket interface
+ * with boost::asio
+ *
+ * This program is in c++ and uses boost::asio instead of libevent/libev.
+ * Requires boost::asio, boost::bind and boost::system
+ *
+ * This is an adaptation of libcurl's "hiperfifo.c" and "evhiperfifo.c"
+ * sample programs. This example implements a subset of the functionality from
+ * hiperfifo.c, for full functionality refer hiperfifo.c or evhiperfifo.c
+ *
+ * Written by Lijo Antony based on hiperfifo.c by Jeff Pohlmeyer
+ *
+ * When running, the program creates an easy handle for a URL and
+ * uses the curl_multi API to fetch it.
+ *
+ * Note:
+ *  For the sake of simplicity, URL is hard coded to "www.google.com"
+ *
+ * This is purely a demo app, all retrieved data is simply discarded by the write
+ * callback.
+ */
+
+
+#include <curl/curl.h>
+#include <boost/asio.hpp>
+#include <boost/bind.hpp>
+
+#define MSG_OUT stdout /* Send info to stdout, change to stderr if you want */
+
+/* boost::asio related objects
+ * using global variables for simplicity
+ */
+boost::asio::io_service io_service;
+boost::asio::deadline_timer timer(io_service);
+std::map<curl_socket_t, boost::asio::ip::tcp::socket *> socket_map;
+
+/* Global information, common to all connections */
+typedef struct _GlobalInfo
+{
+  CURLM *multi;
+  int still_running;
+} GlobalInfo;
+
+/* Information associated with a specific easy handle */
+typedef struct _ConnInfo
+{
+  CURL *easy;
+  char *url;
+  GlobalInfo *global;
+  char error[CURL_ERROR_SIZE];
+} ConnInfo;
+
+static void timer_cb(const boost::system::error_code & error, GlobalInfo *g);
+
+/* Update the event timer after curl_multi library calls */
+static int multi_timer_cb(CURLM *multi, long timeout_ms, GlobalInfo *g)
+{
+  fprintf(MSG_OUT, "\nmulti_timer_cb: timeout_ms %ld", timeout_ms);
+
+  /* cancel running timer */
+  timer.cancel();
+
+  if ( timeout_ms > 0 )
+  {
+    /* update timer */
+    timer.expires_from_now(boost::posix_time::millisec(timeout_ms));
+    timer.async_wait(boost::bind(&timer_cb, _1, g));
+  }
+  else
+  {
+    /* call timeout function immediately */
+    boost::system::error_code error; /*success*/
+    timer_cb(error, g);
+  }
+
+  return 0;
+}
+
+/* Die if we get a bad CURLMcode somewhere */
+static void mcode_or_die(const char *where, CURLMcode code)
+{
+  if ( CURLM_OK != code )
+  {
+    const char *s;
+    switch ( code )
+    {
+    case CURLM_CALL_MULTI_PERFORM: s="CURLM_CALL_MULTI_PERFORM"; break;
+    case CURLM_BAD_HANDLE:         s="CURLM_BAD_HANDLE";         break;
+    case CURLM_BAD_EASY_HANDLE:    s="CURLM_BAD_EASY_HANDLE";    break;
+    case CURLM_OUT_OF_MEMORY:      s="CURLM_OUT_OF_MEMORY";      break;
+    case CURLM_INTERNAL_ERROR:     s="CURLM_INTERNAL_ERROR";     break;
+    case CURLM_UNKNOWN_OPTION:     s="CURLM_UNKNOWN_OPTION";     break;
+    case CURLM_LAST:               s="CURLM_LAST";               break;
+    default: s="CURLM_unknown";
+      break;
+    case     CURLM_BAD_SOCKET:         s="CURLM_BAD_SOCKET";
+      fprintf(MSG_OUT, "\nERROR: %s returns %s", where, s);
+      /* ignore this error */
+      return;
+    }
+    fprintf(MSG_OUT, "\nERROR: %s returns %s", where, s);
+    exit(code);
+  }
+}
+
+/* Check for completed transfers, and remove their easy handles */
+static void check_multi_info(GlobalInfo *g)
+{
+  char *eff_url;
+  CURLMsg *msg;
+  int msgs_left;
+  ConnInfo *conn;
+  CURL *easy;
+  CURLcode res;
+
+  fprintf(MSG_OUT, "\nREMAINING: %d", g->still_running);
+
+  while ((msg = curl_multi_info_read(g->multi, &msgs_left)))
+  {
+    if (msg->msg == CURLMSG_DONE)
+    {
+      easy = msg->easy_handle;
+      res = msg->data.result;
+      curl_easy_getinfo(easy, CURLINFO_PRIVATE, &conn);
+      curl_easy_getinfo(easy, CURLINFO_EFFECTIVE_URL, &eff_url);
+      fprintf(MSG_OUT, "\nDONE: %s => (%d) %s", eff_url, res, conn->error);
+      curl_multi_remove_handle(g->multi, easy);
+      free(conn->url);
+      curl_easy_cleanup(easy);
+      free(conn);
+    }
+  }
+}
+
+/* Called by asio when there is an action on a socket */
+static void event_cb(GlobalInfo * g, boost::asio::ip::tcp::socket * tcp_socket, int action)
+{
+  fprintf(MSG_OUT, "\nevent_cb: action=%d", action);
+
+  CURLMcode rc;
+  rc = curl_multi_socket_action(g->multi, tcp_socket->native_handle(), action, &g->still_running);
+
+  mcode_or_die("event_cb: curl_multi_socket_action", rc);
+  check_multi_info(g);
+
+  if ( g->still_running <= 0 )
+  {
+    fprintf(MSG_OUT, "\nlast transfer done, kill timeout");
+    timer.cancel();
+  }
+}
+
+/* Called by asio when our timeout expires */
+static void timer_cb(const boost::system::error_code & error, GlobalInfo *g)
+{
+  if ( !error)
+  {
+    fprintf(MSG_OUT, "\ntimer_cb: ");
+
+    CURLMcode rc;
+    rc = curl_multi_socket_action(g->multi, CURL_SOCKET_TIMEOUT, 0, &g->still_running);
+
+    mcode_or_die("timer_cb: curl_multi_socket_action", rc);
+    check_multi_info(g);
+  }
+}
+
+/* Clean up any data */
+static void remsock(int *f, GlobalInfo *g)
+{
+  fprintf(MSG_OUT, "\nremsock: ");
+
+  if ( f )
+  {
+    free(f);
+  }
+}
+
+static void setsock(int *fdp, curl_socket_t s, CURL*e, int act, GlobalInfo*g)
+{
+  fprintf(MSG_OUT, "\nsetsock: socket=%d, act=%d, fdp=%p", s, act, fdp);
+
+  std::map<curl_socket_t, boost::asio::ip::tcp::socket *>::iterator it = socket_map.find(s);
+
+  if ( it == socket_map.end() )
+  {
+    fprintf(MSG_OUT, "\nsocket %d is a c-ares socket, ignoring", s);
+    return;
+  }
+
+  boost::asio::ip::tcp::socket * tcp_socket = it->second;
+
+  *fdp = act;
+
+  if ( act == CURL_POLL_IN )
+  {
+    fprintf(MSG_OUT, "\nwatching for socket to become readable");
+
+    tcp_socket->async_read_some(boost::asio::null_buffers(),
+                             boost::bind(&event_cb, g,
+                               tcp_socket,
+                               act));
+  }
+  else if ( act == CURL_POLL_OUT )
+  {
+    fprintf(MSG_OUT, "\nwatching for socket to become writable");
+
+    tcp_socket->async_write_some(boost::asio::null_buffers(),
+                              boost::bind(&event_cb, g,
+                                tcp_socket,
+                                act));
+  }
+  else if ( act == CURL_POLL_INOUT )
+  {
+    fprintf(MSG_OUT, "\nwatching for socket to become readable & writable");
+
+    tcp_socket->async_read_some(boost::asio::null_buffers(),
+                             boost::bind(&event_cb, g,
+                               tcp_socket,
+                               act));
+
+    tcp_socket->async_write_some(boost::asio::null_buffers(),
+                              boost::bind(&event_cb, g,
+                                tcp_socket,
+                                act));
+  }
+}
+
+
+static void addsock(curl_socket_t s, CURL *easy, int action, GlobalInfo *g)
+{
+  int *fdp = (int *)calloc(sizeof(int), 1); /* fdp is used to store current action */
+
+  setsock(fdp, s, easy, action, g);
+  curl_multi_assign(g->multi, s, fdp);
+}
+
+/* CURLMOPT_SOCKETFUNCTION */
+static int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp)
+{
+  fprintf(MSG_OUT, "\nsock_cb: socket=%d, what=%d, sockp=%p", s, what, sockp);
+
+  GlobalInfo *g = (GlobalInfo*) cbp;
+  int *actionp = (int*) sockp;
+  const char *whatstr[]={ "none", "IN", "OUT", "INOUT", "REMOVE"};
+
+  fprintf(MSG_OUT,
+          "\nsocket callback: s=%d e=%p what=%s ", s, e, whatstr[what]);
+
+  if ( what == CURL_POLL_REMOVE )
+  {
+    fprintf(MSG_OUT, "\n");
+    remsock(actionp, g);
+  }
+  else
+  {
+    if ( !actionp )
+    {
+      fprintf(MSG_OUT, "\nAdding data: %s", whatstr[what]);
+      addsock(s, e, what, g);
+    }
+    else
+    {
+      fprintf(MSG_OUT,
+              "\nChanging action from %s to %s",
+              whatstr[*actionp], whatstr[what]);
+      setsock(actionp, s, e, what, g);
+    }
+  }
+  return 0;
+}
+
+
+/* CURLOPT_WRITEFUNCTION */
+static size_t write_cb(void *ptr, size_t size, size_t nmemb, void *data)
+{
+
+  size_t written = size * nmemb;
+  char* pBuffer = (char*)malloc(written + 1);
+
+  strncpy(pBuffer, (const char *)ptr, written);
+  pBuffer [written] = '\0';
+
+  fprintf(MSG_OUT, "%s", pBuffer);
+
+  free(pBuffer);
+
+  return written;
+}
+
+
+/* CURLOPT_PROGRESSFUNCTION */
+static int prog_cb (void *p, double dltotal, double dlnow, double ult,
+                    double uln)
+{
+  ConnInfo *conn = (ConnInfo *)p;
+  (void)ult;
+  (void)uln;
+
+  fprintf(MSG_OUT, "\nProgress: %s (%g/%g)", conn->url, dlnow, dltotal);
+  fprintf(MSG_OUT, "\nProgress: %s (%g)", conn->url, ult);
+
+  return 0;
+}
+
+/* CURLOPT_OPENSOCKETFUNCTION */
+static curl_socket_t opensocket(void *clientp,
+                                curlsocktype purpose,
+                                struct curl_sockaddr *address)
+{
+  fprintf(MSG_OUT, "\nopensocket :");
+
+  curl_socket_t sockfd = CURL_SOCKET_BAD;
+
+  struct sockaddr_in * addr = (struct sockaddr_in *)&(address->addr);
+  char * ip_addr_str = inet_ntoa(addr->sin_addr);
+  unsigned short port = ntohs(addr->sin_port);
+
+  /* create a tcp socket object */
+  boost::asio::ip::address ip_addr = boost::asio::ip::address::from_string(ip_addr_str);
+  boost::asio::ip::tcp::endpoint endpoint(ip_addr, port);
+  boost::asio::ip::tcp::socket * tcp_socket = new boost::asio::ip::tcp::socket(io_service);
+
+  /* connect */
+  boost::system::error_code ec;
+  tcp_socket->connect(endpoint, ec);
+
+  if (ec)
+  {
+    //An error occurred
+    std::cout << std::endl << "Couldn't connect to remote endpoint '" << endpoint << "' [" << ec << "][" << ec.message() << "]";
+    fprintf(MSG_OUT, "\nERROR: Returning CURL_SOCKET_BAD to signal error");
+  }
+  else
+  {
+    sockfd = tcp_socket->native_handle();
+    std::cout << std::endl << "Connected to remote endpoint '" << endpoint << "', with socket : " << sockfd;
+
+    /* save it for monitoring */
+    socket_map.insert(std::pair<curl_socket_t, boost::asio::ip::tcp::socket *>(sockfd, tcp_socket));
+  }
+
+  return sockfd;
+}
+
+/* CURLOPT_SOCKOPTFUNCTION */
+static int sockopt_callback(void *clientp, curl_socket_t curlfd,
+                            curlsocktype purpose)
+{
+  fprintf(MSG_OUT, "\nsockopt_callback :");
+
+  /* This return code was added in libcurl 7.21.5 */
+  return CURL_SOCKOPT_ALREADY_CONNECTED;
+}
+
+/* CURLOPT_CLOSESOCKETFUNCTION */
+static int closesocket(void *clientp, curl_socket_t item)
+{
+  fprintf(MSG_OUT, "\nclosesocket :");
+
+  std::map<curl_socket_t, boost::asio::ip::tcp::socket *>::iterator it = socket_map.find(item);
+
+  if ( it != socket_map.end() )
+  {
+    delete it->second;
+    socket_map.erase(it);
+  }
+
+  return 0;
+}
+
+/* Create a new easy handle, and add it to the global curl_multi */
+static void new_conn(char *url, GlobalInfo *g )
+{
+  ConnInfo *conn;
+  CURLMcode rc;
+
+  conn = (ConnInfo *)calloc(1, sizeof(ConnInfo));
+  memset(conn, 0, sizeof(ConnInfo));
+  conn->error[0]='\0';
+
+  conn->easy = curl_easy_init();
+
+  if ( !conn->easy )
+  {
+    fprintf(MSG_OUT, "\ncurl_easy_init() failed, exiting!");
+    exit(2);
+  }
+  conn->global = g;
+  conn->url = strdup(url);
+  curl_easy_setopt(conn->easy, CURLOPT_URL, conn->url);
+  curl_easy_setopt(conn->easy, CURLOPT_WRITEFUNCTION, write_cb);
+  curl_easy_setopt(conn->easy, CURLOPT_WRITEDATA, &conn);
+  curl_easy_setopt(conn->easy, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(conn->easy, CURLOPT_ERRORBUFFER, conn->error);
+  curl_easy_setopt(conn->easy, CURLOPT_PRIVATE, conn);
+  curl_easy_setopt(conn->easy, CURLOPT_NOPROGRESS, 1L);
+  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSFUNCTION, prog_cb);
+  curl_easy_setopt(conn->easy, CURLOPT_PROGRESSDATA, conn);
+  curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_TIME, 3L);
+  curl_easy_setopt(conn->easy, CURLOPT_LOW_SPEED_LIMIT, 10L);
+
+  /* call this function to get a socket */
+  curl_easy_setopt(conn->easy, CURLOPT_OPENSOCKETFUNCTION, opensocket);
+
+  /* call this function to set options for the socket */
+  curl_easy_setopt(conn->easy, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
+  curl_easy_setopt(conn->easy, CURLOPT_CLOSESOCKETFUNCTION, closesocket);
+
+  fprintf(MSG_OUT,
+          "\nAdding easy %p to multi %p (%s)", conn->easy, g->multi, url);
+  rc = curl_multi_add_handle(g->multi, conn->easy);
+  mcode_or_die("new_conn: curl_multi_add_handle", rc);
+
+  /* note that the add_handle() will set a time-out to trigger very soon so
+     that the necessary socket_action() call will be called by this app */
+}
+
+int main(int argc, char **argv)
+{
+  GlobalInfo g;
+  CURLMcode rc;
+  (void)argc;
+  (void)argv;
+
+  memset(&g, 0, sizeof(GlobalInfo));
+  g.multi = curl_multi_init();
+
+  curl_multi_setopt(g.multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
+  curl_multi_setopt(g.multi, CURLMOPT_SOCKETDATA, &g);
+  curl_multi_setopt(g.multi, CURLMOPT_TIMERFUNCTION, multi_timer_cb);
+  curl_multi_setopt(g.multi, CURLMOPT_TIMERDATA, &g);
+
+  new_conn((char *)"www.google.com", &g);  /* add a URL */
+
+  /* enter io_service run loop */
+  io_service.run();
+
+  curl_multi_cleanup(g.multi);
+
+  fprintf(MSG_OUT, "\ndone.\n");
+  return 0;
+}
-- 
1.7.10.4
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