Constantine Sapuntzakis threaded resolver enhancements

5 files changed, 284 insertions, 431 deletions

diff --git a/lib/hostares.c b/lib/hostares.c
index 94240a6ab..a7f1d1bd2 100644
--- a/lib/hostares.c
+++ b/lib/hostares.c
@@ -350,7 +350,8 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
 #ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
   struct in6_addr in6;
 #endif /* CURLRES_IPV6 */
-  *waitp = FALSE;
+
+  *waitp = 0; /* default to synchronous response */
 
   /* First check if this is an IPv4 address string */
   if(Curl_inet_pton(AF_INET, hostname, &in) > 0) {
@@ -396,7 +397,7 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
     ares_gethostbyname(data->state.areschannel, hostname, family,
                        (ares_host_callback)ares_query_completed_cb, conn);
 
-    *waitp = TRUE; /* please wait for the response */
+    *waitp = 1; /* expect asynchronous response */
   }
   return NULL; /* no struct yet */
 }
diff --git a/lib/hostip.h b/lib/hostip.h
index 85425b6ce..ea2e3cd87 100644
--- a/lib/hostip.h
+++ b/lib/hostip.h
@@ -1,5 +1,5 @@
-#ifndef __HOSTIP_H
-#define __HOSTIP_H
+#ifndef HEADER_CURL_HOSTIP_H
+#define HEADER_CURL_HOSTIP_H
 /***************************************************************************
  *                                  _   _ ____  _
  *  Project                     ___| | | |  _ \| |
@@ -165,6 +165,9 @@ int curl_dogetnameinfo(GETNAMEINFO_QUAL_ARG1 GETNAMEINFO_TYPE_ARG1 sa,
                        int line, const char *source);
 #endif
 
+/* IPv4 threadsafe resolve function used for synch and asynch builds */
+Curl_addrinfo *Curl_ipv4_resolve_r(const char * hostname, int port);
+
 /*
  * Curl_addrinfo_callback() is used when we build with any asynch specialty.
  * Handles end of async request processing. Inserts ai into hostcache when
@@ -214,4 +217,4 @@ void Curl_destroy_thread_data(struct Curl_async *async);
 extern sigjmp_buf curl_jmpenv;
 #endif
 
-#endif
+#endif /* HEADER_CURL_HOSTIP_H */
diff --git a/lib/hostip4.c b/lib/hostip4.c
index b4f6bd9d3..b637ce6ec 100644
--- a/lib/hostip4.c
+++ b/lib/hostip4.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2009, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2010, Daniel Stenberg, <daniel@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
@@ -87,8 +87,7 @@ bool Curl_ipvalid(struct SessionHandle *data)
   return TRUE; /* OK, proceed */
 }
 
-#ifdef CURLRES_SYNCH /* the functions below are for synchronous resolves */
-
+#ifdef CURLRES_SYNCH
 /*
  * Curl_getaddrinfo() - the ipv4 synchronous version.
  *
@@ -110,6 +109,33 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
                                 int port,
                                 int *waitp)
 {
+  Curl_addrinfo *ai = NULL;
+
+#ifdef CURL_DISABLE_VERBOSE_STRINGS
+  (void)conn;
+#endif
+
+  *waitp = 0; /* synchronous response only */
+
+  ai = Curl_ipv4_resolve_r(hostname, port);
+  if(!ai)
+    infof(conn->data, "Curl_ipv4_resolve_r failed for %s\n", hostname);
+
+  return ai;  
+}
+#endif /* CURLRES_SYNCH */
+#endif /* CURLRES_IPV4 */
+
+/*
+ * Curl_ipv4_resolve_r() - ipv4 threadsafe resolver function.
+ *
+ * This is used for both synchronous and asynchronous resolver builds,
+ * implying that only threadsafe code and function calls may be used.
+ *
+ */
+Curl_addrinfo *Curl_ipv4_resolve_r(const char *hostname,
+                                   int port)
+{
 #if defined(HAVE_GETHOSTBYNAME_R_3)
   int res;
 #endif
@@ -118,17 +144,28 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
   struct in_addr in;
   struct hostent *buf = NULL;
 
-#ifdef CURL_DISABLE_VERBOSE_STRINGS
-  (void)conn;
-#endif
-
-  *waitp = 0; /* don't wait, we act synchronously */
-
   if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
     /* This is a dotted IP address 123.123.123.123-style */
     return Curl_ip2addr(AF_INET, &in, hostname, port);
 
-#if defined(HAVE_GETHOSTBYNAME_R)
+#if defined(HAVE_GETADDRINFO_THREADSAFE)
+  else { 
+    struct addrinfo hints;
+    char sbuf[NI_MAXSERV];
+    char *sbufptr = NULL;
+    int error;
+
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = PF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+    if (port) {
+      snprintf(sbuf, sizeof(sbuf), "%d", port);
+      sbufptr = sbuf;
+    }
+    hints.ai_flags = AI_CANONNAME;
+    error = Curl_getaddrinfo_ex(hostname, sbufptr, &hints, &ai);
+
+#elif defined(HAVE_GETHOSTBYNAME_R)
   /*
    * gethostbyname_r() is the preferred resolve function for many platforms.
    * Since there are three different versions of it, the following code is
@@ -260,8 +297,7 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
     }
     else
 #endif /* HAVE_GETHOSTBYNAME_R_3 */
-      {
-      infof(conn->data, "gethostbyname_r(2) failed for %s\n", hostname);
+    {
       h = NULL; /* set return code to NULL */
       free(buf);
     }
@@ -276,8 +312,6 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
 #else
     h = gethostbyname(hostname);
 #endif
-    if(!h)
-      infof(conn->data, "gethostbyname(2) failed for %s\n", hostname);
 #endif /*HAVE_GETHOSTBYNAME_R */
   }
 
@@ -290,7 +324,3 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
 
   return ai;
 }
-
-#endif /* CURLRES_SYNCH */
-#endif /* CURLRES_IPV4 */
-
diff --git a/lib/hostip6.c b/lib/hostip6.c
index ba50a0360..bb2c5e46d 100644
--- a/lib/hostip6.c
+++ b/lib/hostip6.c
@@ -126,7 +126,7 @@ bool Curl_ipvalid(struct SessionHandle *data)
   return TRUE;
 }
 
-#if !defined(USE_THREADING_GETADDRINFO) && !defined(CURLRES_ARES)
+#if defined(CURLRES_SYNCH)
 
 #ifdef DEBUG_ADDRINFO
 static void dump_addrinfo(struct connectdata *conn, const Curl_addrinfo *ai)
@@ -170,7 +170,7 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
   int pf;
   struct SessionHandle *data = conn->data;
 
-  *waitp=0; /* don't wait, we have the response now */
+  *waitp = 0; /* synchronous response only */
 
   /*
    * Check if a limited name resolve has been requested.
@@ -234,6 +234,6 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
 
   return res;
 }
-#endif /* !USE_THREADING_GETADDRINFO && !CURLRES_ARES */
+#endif /* CURLRES_SYNCH */
 #endif /* CURLRES_IPV6 */
 
diff --git a/lib/hostthre.c b/lib/hostthre.c
index 32e946ccb..2205c8fdd 100644
--- a/lib/hostthre.c
+++ b/lib/hostthre.c
@@ -50,8 +50,14 @@
 #include <stdlib.h>
 #endif
 
-#ifdef HAVE_PROCESS_H
-#include <process.h>
+#if defined(USE_THREADS_POSIX)
+#  ifdef HAVE_PTHREAD_H
+#    include <pthread.h>
+#  endif
+#elif defined(USE_THREADS_WIN32)
+#  ifdef HAVE_PROCESS_H
+#    include <process.h>
+#  endif
 #endif
 
 #if (defined(NETWARE) && defined(__NOVELL_LIBC__))
@@ -68,12 +74,12 @@
 #include "url.h"
 #include "multiif.h"
 #include "inet_pton.h"
+#include "inet_ntop.h"
+#include "curl_threads.h"
 
 #define _MPRINTF_REPLACE /* use our functions only */
 #include <curl/mprintf.h>
 
-#include "inet_ntop.h"
-
 #include "curl_memory.h"
 /* The last #include file should be: */
 #include "memdebug.h"
@@ -83,7 +89,7 @@
 #endif
 
 /***********************************************************************
- * Only for Windows threaded name resolves builds
+ * Only for threaded name resolves builds
  **********************************************************************/
 #ifdef CURLRES_THREADED
 
@@ -92,251 +98,162 @@ static bool init_resolve_thread(struct connectdata *conn,
                                 const char *hostname, int port,
                                 const struct addrinfo *hints);
 
-#ifdef CURLRES_IPV4
-  #define THREAD_FUNC  gethostbyname_thread
-  #define THREAD_NAME "gethostbyname_thread"
-#else
-  #define THREAD_FUNC  getaddrinfo_thread
-  #define THREAD_NAME "getaddrinfo_thread"
-#endif
-
-struct thread_data {
-  HANDLE thread_hnd;
-  unsigned thread_id;
-  DWORD  thread_status;
-  curl_socket_t dummy_sock;   /* dummy for Curl_resolv_fdset() */
-  HANDLE mutex_waiting;  /* marks that we are still waiting for a resolve */
-  HANDLE event_resolved; /* marks that the thread obtained the information */
-  HANDLE event_thread_started; /* marks that the thread has initialized and
-                                  started */
-  HANDLE mutex_terminate; /* serializes access to flag_terminate */
-  HANDLE event_terminate; /* flag for thread to terminate instead of calling
-                             callbacks */
-#ifdef CURLRES_IPV6
-  struct addrinfo hints;
-#endif
-};
 
 /* Data for synchronization between resolver thread and its parent */
 struct thread_sync_data {
-  HANDLE mutex_waiting;   /* thread_data.mutex_waiting duplicate */
-  HANDLE mutex_terminate; /* thread_data.mutex_terminate duplicate */
-  HANDLE event_terminate; /* thread_data.event_terminate duplicate */
+  curl_mutex_t * mtx;
+  int done;
+
   char * hostname;        /* hostname to resolve, Curl_async.hostname
                              duplicate */
+  int port;
+  int sock_error;
+  Curl_addrinfo *res;
+#ifdef HAVE_GETADDRINFO
+  struct addrinfo hints;
+#endif
+};
+
+struct thread_data {
+  curl_thread_t thread_hnd;
+  curl_socket_t dummy_sock;
+  unsigned int poll_interval;
+  int interval_end;
+  struct thread_sync_data tsd;
 };
 
+static struct thread_sync_data * conn_thread_sync_data(struct connectdata *conn)
+{
+  return &(((struct thread_data *)conn->async.os_specific)->tsd);
+}
+
+#define CONN_THREAD_SYNC_DATA(conn) &(((conn)->async.os_specific)->tsd);
+
 /* Destroy resolver thread synchronization data */
 static
 void destroy_thread_sync_data(struct thread_sync_data * tsd)
 {
+  if (tsd->mtx) {
+    Curl_mutex_destroy(tsd->mtx);
+    free(tsd->mtx);
+  }
+
   if(tsd->hostname)
     free(tsd->hostname);
-  if(tsd->event_terminate)
-    CloseHandle(tsd->event_terminate);
-  if(tsd->mutex_terminate)
-    CloseHandle(tsd->mutex_terminate);
-  if(tsd->mutex_waiting)
-    CloseHandle(tsd->mutex_waiting);
+  
+  if (tsd->res)
+    Curl_freeaddrinfo(tsd->res);
+
   memset(tsd,0,sizeof(*tsd));
 }
 
 /* Initialize resolver thread synchronization data */
 static
-BOOL init_thread_sync_data(struct thread_data * td,
+int init_thread_sync_data(struct thread_sync_data * tsd,
                            const char * hostname,
-                           struct thread_sync_data * tsd)
+			   int port,
+			   const struct addrinfo *hints)
 {
-  HANDLE curr_proc = GetCurrentProcess();
-
   memset(tsd, 0, sizeof(*tsd));
-  if(!DuplicateHandle(curr_proc, td->mutex_waiting,
-                       curr_proc, &tsd->mutex_waiting, 0, FALSE,
-                       DUPLICATE_SAME_ACCESS)) {
-    /* failed to duplicate the mutex, no point in continuing */
-    destroy_thread_sync_data(tsd);
-    return FALSE;
-  }
-  if(!DuplicateHandle(curr_proc, td->mutex_terminate,
-                       curr_proc, &tsd->mutex_terminate, 0, FALSE,
-                       DUPLICATE_SAME_ACCESS)) {
-    /* failed to duplicate the mutex, no point in continuing */
-    destroy_thread_sync_data(tsd);
-    return FALSE;
-  }
-  if(!DuplicateHandle(curr_proc, td->event_terminate,
-                       curr_proc, &tsd->event_terminate, 0, FALSE,
-                       DUPLICATE_SAME_ACCESS)) {
-    /* failed to duplicate the event, no point in continuing */
-    destroy_thread_sync_data(tsd);
-    return FALSE;
-  }
+
+  tsd->port = port;
+#ifdef CURLRES_IPV6
+  DEBUGASSERT(hints);
+  tsd->hints = *hints;
+#else
+  (void) hints;
+#endif
+
+  tsd->mtx = malloc(sizeof(curl_mutex_t));
+  if (tsd->mtx == NULL) goto err_exit;
+
+  Curl_mutex_init(tsd->mtx);
+
+  tsd->sock_error = CURL_ASYNC_SUCCESS;
+
   /* Copying hostname string because original can be destroyed by parent
    * thread during gethostbyname execution.
    */
   tsd->hostname = strdup(hostname);
-  if(!tsd->hostname) {
-    /* Memory allocation failed */
-    destroy_thread_sync_data(tsd);
-    return FALSE;
-  }
-  return TRUE;
-}
+  if (!tsd->hostname) goto err_exit;
 
-/* acquire resolver thread synchronization */
-static
-BOOL acquire_thread_sync(struct thread_sync_data * tsd)
-{
-  /* is the thread initiator still waiting for us ? */
-  if(WaitForSingleObject(tsd->mutex_waiting, 0) == WAIT_TIMEOUT) {
-    /* yes, it is */
-
-    /* Waiting access to event_terminate */
-    if(WaitForSingleObject(tsd->mutex_terminate, INFINITE) != WAIT_OBJECT_0) {
-      /* Something went wrong - now just ignoring */
-    }
-    else {
-      if(WaitForSingleObject(tsd->event_terminate, 0) != WAIT_TIMEOUT) {
-        /* Parent thread signaled us to terminate.
-         * This means that all data in conn->async is now destroyed
-         * and we cannot use it.
-         */
-      }
-      else {
-        return TRUE;
-      }
-    }
-  }
-  return FALSE;
-}
+  return 1;
 
-/* release resolver thread synchronization */
-static
-void release_thread_sync(struct thread_sync_data * tsd)
-{
-  ReleaseMutex(tsd->mutex_terminate);
+ err_exit:
+  /* Memory allocation failed */
+  destroy_thread_sync_data(tsd);
+  return 0;
 }
 
-#if defined(CURLRES_IPV4)
 /*
- * gethostbyname_thread() resolves a name, calls the Curl_addrinfo_callback
- * and then exits.
- *
- * For builds without ARES/ENABLE_IPV6, create a resolver thread and wait on
- * it.
+ * gethostbyname_thread() resolves a name and then exits.
  */
-static unsigned __stdcall gethostbyname_thread (void *arg)
+static unsigned int CURL_STDCALL gethostbyname_thread (void *arg)
 {
-  struct connectdata *conn = (struct connectdata*) arg;
-  struct thread_data *td = (struct thread_data*) conn->async.os_specific;
-  struct hostent *he;
-  int    rc = 0;
-
-  /* Duplicate the passed mutex and event handles.
-   * This allows us to use it even after the container gets destroyed
-   * due to a resolver timeout.
-   */
-  struct thread_sync_data tsd = { 0,0,0,NULL };
+  struct thread_sync_data *tsd = (struct thread_sync_data *)arg;
 
-  if(!init_thread_sync_data(td, conn->async.hostname, &tsd)) {
-    /* thread synchronization data initialization failed */
-    return (unsigned)-1;
-  }
-
-  conn->async.status = NO_DATA;  /* pending status */
-  SET_SOCKERRNO(conn->async.status);
+  tsd->res = Curl_ipv4_resolve_r(tsd->hostname, tsd->port);
 
-  /* Signaling that we have initialized all copies of data and handles we
-     need */
-  SetEvent(td->event_thread_started);
+  if (!tsd->res) {
+    tsd->sock_error = SOCKERRNO;
+    if (tsd->sock_error == 0)
+      tsd->sock_error = ENOMEM;
+  } 
 
-  he = gethostbyname (tsd.hostname);
+  Curl_mutex_acquire(tsd->mtx);
+  tsd->done = 1;
+  Curl_mutex_release(tsd->mtx);
 
-  /* is parent thread waiting for us and are we able to access conn members? */
-  if(acquire_thread_sync(&tsd)) {
-    Curl_addrinfo *ai = Curl_he2ai(he, conn->async.port);
+  return 0;
+}
 
-    /* Mark that we have obtained the information, and that we are calling
-     * back with it. */
-    SetEvent(td->event_resolved);
-    if(ai) {
-      rc = Curl_addrinfo_callback(conn, CURL_ASYNC_SUCCESS, ai);
-    }
-    else {
-      rc = Curl_addrinfo_callback(conn, SOCKERRNO, NULL);
-    }
-    release_thread_sync(&tsd);
-  }
+static int getaddrinfo_complete(struct connectdata *conn)
+{
+  struct thread_sync_data *tsd = conn_thread_sync_data(conn);
+  int rc;
 
-  /* clean up */
-  destroy_thread_sync_data(&tsd);
+  rc = Curl_addrinfo_callback(conn, tsd->sock_error, tsd->res); 
+  /* The tsd->res structure has been copied to async.dns and perhaps the DNS cache.
+     Set our copy to NULL so destroy_thread_sync_data doesn't free it.
+   */
+  tsd->res = NULL;
 
-  return (rc);
-  /* An implicit _endthreadex() here */
+  return rc;
 }
 
-#elif defined(CURLRES_IPV6)
+
+#if defined(HAVE_GETADDRINFO)
 
 /*
- * getaddrinfo_thread() resolves a name, calls Curl_addrinfo_callback and then
- * exits.
+ * getaddrinfo_thread() resolves a name and then exits.
  *
  * For builds without ARES, but with ENABLE_IPV6, create a resolver thread
  * and wait on it.
  */
-static unsigned __stdcall getaddrinfo_thread (void *arg)
+static unsigned int CURL_STDCALL getaddrinfo_thread (void *arg)
 {
-  struct connectdata *conn = (struct connectdata*) arg;
-  struct thread_data *td   = (struct thread_data*) conn->async.os_specific;
-  Curl_addrinfo      *res;
+  struct thread_sync_data *tsd = (struct thread_sync_data*)arg;
   char   service [NI_MAXSERV];
-  int    rc;
-  struct addrinfo hints = td->hints;
-
-  /* Duplicate the passed mutex handle.
-   * This allows us to use it even after the container gets destroyed
-   * due to a resolver timeout.
-   */
-  struct thread_sync_data tsd = { 0,0,0,NULL };
-
-  if(!init_thread_sync_data(td, conn->async.hostname, &tsd)) {
-    /* thread synchronization data initialization failed */
-    return -1;
-  }
-
-  itoa(conn->async.port, service, 10);
-
-  conn->async.status = NO_DATA;  /* pending status */
-  SET_SOCKERRNO(conn->async.status);
+  int rc;
 
-  /* Signaling that we have initialized all copies of data and handles we
-     need */
-  SetEvent(td->event_thread_started);
+  snprintf(service, sizeof(service), "%d", tsd->port);
 
-  rc = Curl_getaddrinfo_ex(tsd.hostname, service, &hints, &res);
+  rc = Curl_getaddrinfo_ex(tsd->hostname, service, &tsd->hints, &tsd->res);
 
-  /* is parent thread waiting for us and are we able to access conn members? */
-  if(acquire_thread_sync(&tsd)) {
-    /* Mark that we have obtained the information, and that we are calling
-       back with it. */
-    SetEvent(td->event_resolved);
-
-    if(rc == 0) {
-      rc = Curl_addrinfo_callback(conn, CURL_ASYNC_SUCCESS, res);
-    }
-    else {
-      rc = Curl_addrinfo_callback(conn, SOCKERRNO, NULL);
-    }
-    release_thread_sync(&tsd);
+  if (rc != 0) {
+    tsd->sock_error = SOCKERRNO;
+    if (tsd->sock_error == 0)
+      tsd->sock_error = ENOMEM;
   }
 
-  /* clean up */
-  destroy_thread_sync_data(&tsd);
+  Curl_mutex_acquire(tsd->mtx);
+  tsd->done = 1;
+  Curl_mutex_release(tsd->mtx);
 
-  return (rc);
-  /* An implicit _endthreadex() here */
+  return 0;
 }
-#endif
+
+#endif /* HAVE_GETADDRINFO */
 
 /*
  * Curl_destroy_thread_data() cleans up async resolver data and thread handle.
@@ -349,39 +266,15 @@ void Curl_destroy_thread_data (struct Curl_async *async)
 
   if(async->os_specific) {
     struct thread_data *td = (struct thread_data*) async->os_specific;
-    curl_socket_t sock = td->dummy_sock;
-
-    if(td->mutex_terminate && td->event_terminate) {
-      /* Signaling resolver thread to terminate */
-      if(WaitForSingleObject(td->mutex_terminate, INFINITE) == WAIT_OBJECT_0) {
-        SetEvent(td->event_terminate);
-        ReleaseMutex(td->mutex_terminate);
-      }
-      else {
-        /* Something went wrong - just ignoring it */
-      }
-    }
-
-    if(td->mutex_terminate)
-      CloseHandle(td->mutex_terminate);
-    if(td->event_terminate)
-      CloseHandle(td->event_terminate);
-    if(td->event_thread_started)
-      CloseHandle(td->event_thread_started);
 
-    if(sock != CURL_SOCKET_BAD)
-      sclose(sock);
-
-    /* destroy the synchronization objects */
-    if(td->mutex_waiting)
-      CloseHandle(td->mutex_waiting);
-    td->mutex_waiting = NULL;
-    if(td->event_resolved)
-      CloseHandle(td->event_resolved);
-
-    if(td->thread_hnd)
-      CloseHandle(td->thread_hnd);
+    if (td->dummy_sock != CURL_SOCKET_BAD)
+      sclose(td->dummy_sock);
 
+    if (td->thread_hnd != curl_thread_t_null)
+      Curl_thread_join(&td->thread_hnd);
+ 
+    destroy_thread_sync_data(&td->tsd);
+    
     free(async->os_specific);
   }
   async->hostname = NULL;
@@ -399,114 +292,58 @@ static bool init_resolve_thread (struct connectdata *conn,
                                  const struct addrinfo *hints)
 {
   struct thread_data *td = calloc(1, sizeof(struct thread_data));
-  HANDLE thread_and_event[2] = {0};
+  int err = ENOMEM;
 
-  if(!td) {
-    SET_ERRNO(ENOMEM);
-    return FALSE;
-  }
-
-  Curl_safefree(conn->async.hostname);
-  conn->async.hostname = strdup(hostname);
-  if(!conn->async.hostname) {
-    free(td);
-    SET_ERRNO(ENOMEM);
-    return FALSE;
-  }
+  conn->async.os_specific = (void*) td;
+  if(!td) 
+    goto err_exit;
 
   conn->async.port = port;
   conn->async.done = FALSE;
   conn->async.status = 0;
   conn->async.dns = NULL;
-  conn->async.os_specific = (void*) td;
   td->dummy_sock = CURL_SOCKET_BAD;
+  td->thread_hnd = curl_thread_t_null;
 
-  /* Create the mutex used to inform the resolver thread that we're
-   * still waiting, and take initial ownership.
-   */
-  td->mutex_waiting = CreateMutex(NULL, TRUE, NULL);
-  if(td->mutex_waiting == NULL) {
-    Curl_destroy_thread_data(&conn->async);
-    SET_ERRNO(EAGAIN);
-    return FALSE;
-  }
+  if (!init_thread_sync_data(&td->tsd, hostname, port, hints)) 
+    goto err_exit;
 
-  /* Create the event that the thread uses to inform us that it's
-   * done resolving. Do not signal it.
-   */
-  td->event_resolved = CreateEvent(NULL, TRUE, FALSE, NULL);
-  if(td->event_resolved == NULL) {
-    Curl_destroy_thread_data(&conn->async);
-    SET_ERRNO(EAGAIN);
-    return FALSE;
-  }
-  /* Create the mutex used to serialize access to event_terminated
-   * between us and resolver thread.
-   */
-  td->mutex_terminate = CreateMutex(NULL, FALSE, NULL);
-  if(td->mutex_terminate == NULL) {
-    Curl_destroy_thread_data(&conn->async);
-    SET_ERRNO(EAGAIN);
-    return FALSE;
-  }
-  /* Create the event used to signal thread that it should terminate.
-   */
-  td->event_terminate = CreateEvent(NULL, TRUE, FALSE, NULL);
-  if(td->event_terminate == NULL) {
-    Curl_destroy_thread_data(&conn->async);
-    SET_ERRNO(EAGAIN);
-    return FALSE;
-  }
-  /* Create the event used by thread to inform it has initialized its own data.
-   */
-  td->event_thread_started = CreateEvent(NULL, TRUE, FALSE, NULL);
-  if(td->event_thread_started == NULL) {
-    Curl_destroy_thread_data(&conn->async);
-    SET_ERRNO(EAGAIN);
-    return FALSE;
-  }
+  Curl_safefree(conn->async.hostname);
+  conn->async.hostname = strdup(hostname);
+  if(!conn->async.hostname)
+    goto err_exit;
 
-#ifdef _WIN32_WCE
-  td->thread_hnd = (HANDLE) CreateThread(NULL, 0,
-                                         (LPTHREAD_START_ROUTINE) THREAD_FUNC,
-                                         conn, 0, &td->thread_id);
-#else
-  td->thread_hnd = (HANDLE) _beginthreadex(NULL, 0, THREAD_FUNC,
-                                           conn, 0, &td->thread_id);
+#ifdef WIN32
+  /* This socket is only to keep Curl_resolv_fdset() and select() happy;
+   * should never become signalled for read since it's unbound but
+   * Windows needs at least 1 socket in select().
+   */
+  td->dummy_sock = socket(AF_INET, SOCK_DGRAM, 0);
+  if (td->dummy_sock == CURL_SOCKET_BAD)
+    goto err_exit;
 #endif
 
-#ifdef CURLRES_IPV6
-  DEBUGASSERT(hints);
-  td->hints = *hints;
+#ifdef HAVE_GETADDRINFO
+  td->thread_hnd = Curl_thread_create(getaddrinfo_thread, &td->tsd);
 #else
-  (void) hints;
+  td->thread_hnd = Curl_thread_create(gethostbyname_thread, &td->tsd);
 #endif
 
   if(!td->thread_hnd) {
 #ifndef _WIN32_WCE
-     SET_ERRNO(errno);
+    err = errno;
 #endif
-     Curl_destroy_thread_data(&conn->async);
-     return FALSE;
+    goto err_exit;
   }
-  /* Waiting until the thread will initialize its data or it will exit due errors.
-   */
-  thread_and_event[0] = td->thread_hnd;
-  thread_and_event[1] = td->event_thread_started;
-  if(WaitForMultipleObjects(sizeof(thread_and_event) /
-                             sizeof(thread_and_event[0]),
-                             (const HANDLE*)thread_and_event, FALSE,
-                             INFINITE) == WAIT_FAILED) {
-    /* The resolver thread has been created,
-     * most probably it works now - ignoring this "minor" error
-     */
-  }
-  /* This socket is only to keep Curl_resolv_fdset() and select() happy;
-   * should never become signalled for read/write since it's unbound but
-   * Windows needs atleast 1 socket in select().
-   */
-  td->dummy_sock = socket(AF_INET, SOCK_DGRAM, 0);
+
   return TRUE;
+
+ err_exit:
+  Curl_destroy_thread_data(&conn->async);
+
+  SET_ERRNO(err);
+
+  return FALSE;
 }
 
 
@@ -523,84 +360,33 @@ CURLcode Curl_wait_for_resolv(struct connectdata *conn,
 {
   struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
   struct SessionHandle *data = conn->data;
-  long   timeout;
-  DWORD  status;
   CURLcode rc;
 
   DEBUGASSERT(conn && td);
 
-  /* now, see if there's a connect timeout or a regular timeout to
-     use instead of the default one */
-  timeout =
-    conn->data->set.connecttimeout ? conn->data->set.connecttimeout :
-    conn->data->set.timeout ? conn->data->set.timeout :
-    CURL_TIMEOUT_RESOLVE * 1000; /* default name resolve timeout */
-
   /* wait for the thread to resolve the name */
-  status = WaitForSingleObject(td->event_resolved, timeout);
-
-  /* mark that we are now done waiting */
-  ReleaseMutex(td->mutex_waiting);
-
-  /* close our handle to the mutex, no point in hanging on to it */
-  CloseHandle(td->mutex_waiting);
-  td->mutex_waiting = NULL;
-
-  /* close the event handle, it's useless now */
-  CloseHandle(td->event_resolved);
-  td->event_resolved = NULL;
-
-  /* has the resolver thread succeeded in resolving our query ? */
-  if(status == WAIT_OBJECT_0) {
-    /* wait for the thread to exit, it's in the callback sequence */
-    if(WaitForSingleObject(td->thread_hnd, 5000) == WAIT_TIMEOUT) {
-      TerminateThread(td->thread_hnd, 0);
-      conn->async.done = TRUE;
-      td->thread_status = (DWORD)-1;
-    }
-    else {
-      /* Thread finished before timeout; propagate Winsock error to this
-       * thread.  'conn->async.done = TRUE' is set in
-       * Curl_addrinfo4/6_callback().
-       */
-      SET_SOCKERRNO(conn->async.status);
-      GetExitCodeThread(td->thread_hnd, &td->thread_status);
-    }
-  }
-  else {
-    conn->async.done = TRUE;
-    td->thread_status = (DWORD)-1;
+  if (Curl_thread_join(&td->thread_hnd)) {
+    rc = getaddrinfo_complete(conn);
+  } else {
+    DEBUGASSERT(0);    
   }
 
+  conn->async.done = TRUE;
+    
   if(entry)
     *entry = conn->async.dns;
 
-  rc = CURLE_OK;
-
   if(!conn->async.dns) {
     /* a name was not resolved */
-    if(td->thread_status == CURLE_OUT_OF_MEMORY) {
-      rc = CURLE_OUT_OF_MEMORY;
-      failf(data, "Could not resolve host: %s", curl_easy_strerror(rc));
-    }
-    else if(conn->async.done) {
-      if(conn->bits.httpproxy) {
-        failf(data, "Could not resolve proxy: %s; %s",
-              conn->proxy.dispname, Curl_strerror(conn, conn->async.status));
-        rc = CURLE_COULDNT_RESOLVE_PROXY;
-      }
-      else {
-        failf(data, "Could not resolve host: %s; %s",
-              conn->host.name, Curl_strerror(conn, conn->async.status));
-        rc = CURLE_COULDNT_RESOLVE_HOST;
-      }
-    }
-    else if(td->thread_status == (DWORD)-1 || conn->async.status == NO_DATA) {
-      failf(data, "Resolving host timed out: %s", conn->host.name);
-      rc = CURLE_OPERATION_TIMEDOUT;
+    if (conn->bits.httpproxy) {
+      failf(data, "Could not resolve proxy: %s; %s",
+            conn->async.hostname, Curl_strerror(conn, conn->async.status));
+      rc = CURLE_COULDNT_RESOLVE_PROXY;
+    } else {
+      failf(data, "Could not resolve host: %s; %s",
+            conn->async.hostname, Curl_strerror(conn, conn->async.status));
+      rc = CURLE_COULDNT_RESOLVE_HOST;
     }
-    else
-      rc = CURLE_OPERATION_TIMEDOUT;
   }
 
   Curl_destroy_thread_data(&conn->async);
@@ -620,19 +406,57 @@ CURLcode Curl_is_resolved(struct connectdata *conn,
                           struct Curl_dns_entry **entry)
 {
   struct SessionHandle *data = conn->data;
-
+  struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
+  int done = 0;
+ 
   *entry = NULL;
 
-  if(conn->async.done) {
-    /* we're done */
+  if (!td) {
+    DEBUGASSERT(td);
+    return CURLE_COULDNT_RESOLVE_HOST;
+  }
+
+  Curl_mutex_acquire(td->tsd.mtx);
+  done = td->tsd.done;
+  Curl_mutex_release(td->tsd.mtx);
+
+  if (done) { 
+    getaddrinfo_complete(conn);
+    if (td->poll_interval != 0)
+        Curl_expire(conn->data, 0);
     Curl_destroy_thread_data(&conn->async);
+
     if(!conn->async.dns) {
       failf(data, "Could not resolve host: %s; %s",
             conn->host.name, Curl_strerror(conn, conn->async.status));
       return CURLE_COULDNT_RESOLVE_HOST;
     }
     *entry = conn->async.dns;
+  } else {
+    /* poll for name lookup done with exponential backoff up to 250ms */
+    int elapsed;
+
+    elapsed = Curl_tvdiff(Curl_tvnow(), data->progress.t_startsingle);
+    if (elapsed < 0) {
+      elapsed = 0;
+    }
+
+    if (td->poll_interval == 0) {
+      /* Start at 1ms poll interval */
+      td->poll_interval = 1;
+    } else if (elapsed >= td->interval_end) {
+      /* Back-off exponentially if last interval expired  */
+      td->poll_interval *= 2;
+    }
+
+    if (td->poll_interval > 250)
+      td->poll_interval = 250;
+
+    td->interval_end = elapsed + td->poll_interval;
+
+    Curl_expire(conn->data, td->poll_interval);
   }
+
   return CURLE_OK;
 }
 
@@ -645,18 +469,18 @@ int Curl_resolv_getsock(struct connectdata *conn,
 
   if(td && td->dummy_sock != CURL_SOCKET_BAD) {
     if(numsocks) {
-      /* return one socket waiting for writable, even though this is just
+      /* return one socket waiting for readable, even though this is just
          a dummy */
       socks[0] = td->dummy_sock;
-      return GETSOCK_WRITESOCK(0);
+      return GETSOCK_READSOCK(0);
     }
   }
   return 0;
 }
 
-#ifdef CURLRES_IPV4
+#if !defined(HAVE_GETADDRINFO)
 /*
- * Curl_getaddrinfo() - for Windows threading without ENABLE_IPV6.
+ * Curl_getaddrinfo() - for platforms without getaddrinfo
  */
 Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
                                 const char *hostname,
@@ -667,7 +491,7 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
   struct SessionHandle *data = conn->data;
   struct in_addr in;
 
-  *waitp = 0; /* don't wait, we act synchronously */
+  *waitp = 0; /* default to synchronous response */
 
   if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
     /* This is a dotted IP address 123.123.123.123-style */
@@ -675,27 +499,18 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
 
   /* fire up a new resolver thread! */
   if(init_resolve_thread(conn, hostname, port, NULL)) {
-    *waitp = TRUE;  /* please wait for the response */
+    *waitp = 1; /* expect asynchronous response */
     return NULL;
   }
 
   /* fall-back to blocking version */
-  infof(data, "init_resolve_thread() failed for %s; %s\n",
-        hostname, Curl_strerror(conn, ERRNO));
-
-  h = gethostbyname(hostname);
-  if(!h) {
-    infof(data, "gethostbyname(2) failed for %s:%d; %s\n",
-          hostname, port, Curl_strerror(conn, SOCKERRNO));
-    return NULL;
-  }
-  return Curl_he2ai(h, port);
+  return Curl_ipv4_resolve_r(hostname, port);
 }
-#endif /* CURLRES_IPV4 */
 
-#ifdef CURLRES_IPV6
+#else /* HAVE_GETADDRINFO */
+
 /*
- * Curl_getaddrinfo() - for Windows threading IPv6 enabled
+ * Curl_getaddrinfo() - for getaddrinfo
  */
 Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
                                 const char *hostname,
@@ -706,11 +521,12 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
   Curl_addrinfo *res;
   int error;
   char sbuf[NI_MAXSERV];
-  int pf;
+  int pf = PF_INET;
   struct SessionHandle *data = conn->data;
 
-  *waitp = FALSE; /* default to synch response */
+  *waitp = 0; /* default to synchronous response */
 
+#if !defined(CURLRES_IPV4)
   /*
    * Check if a limited name resolve has been requested.
    */
@@ -743,6 +559,7 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
       sclose(s);
     }
   }
+#endif /* !CURLRES_IPV4 */
 
   memset(&hints, 0, sizeof(hints));
   hints.ai_family = pf;
@@ -750,11 +567,11 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
 #if 0 /* removed nov 8 2005 before 7.15.1 */
   hints.ai_flags = AI_CANONNAME;
 #endif
-  itoa(port, sbuf, 10);
+  snprintf(sbuf, sizeof(sbuf), "%d", port);
 
   /* fire up a new resolver thread! */
   if(init_resolve_thread(conn, hostname, port, &hints)) {
-    *waitp = TRUE;  /* please wait for the response */
+    *waitp = 1; /* expect asynchronous response */
     return NULL;
   }
 
@@ -770,5 +587,7 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
   }
   return res;
 }
-#endif /* CURLRES_IPV6 */
+
+#endif /* HAVE_GETADDRINFO */
+
 #endif /* CURLRES_THREADED */