async resolvers: further cleanups

asyn-ares.c and asyn-thread.c are two separate backends that implement
the same (internal) async resolver API for libcurl to use. Backend is
specified at build time.

The internal resolver API is defined in asyn.h for asynch resolvers.

1 files changed, 610 insertions, 0 deletions

diff --git a/lib/asyn-ares.c b/lib/asyn-ares.c
new file mode 100644
index 000000000..6b71e0384
--- /dev/null
+++ b/lib/asyn-ares.c
@@ -0,0 +1,610 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2011, 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
+ * 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.
+ *
+ ***************************************************************************/
+
+#include "setup.h"
+
+#include <string.h>
+
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>     /* required for free() prototypes */
+#endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>     /* for the close() proto */
+#endif
+#ifdef __VMS
+#include <in.h>
+#include <inet.h>
+#include <stdlib.h>
+#endif
+
+#ifdef HAVE_PROCESS_H
+#include <process.h>
+#endif
+
+#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
+#undef in_addr_t
+#define in_addr_t unsigned long
+#endif
+
+/***********************************************************************
+ * Only for ares-enabled builds
+ * And only for functions that fulfill the asynch resolver backend API
+ * as defined in asyn.h, nothing else belongs in this file!
+ **********************************************************************/
+
+#ifdef CURLRES_ARES
+
+#include "urldata.h"
+#include "sendf.h"
+#include "hostip.h"
+#include "hash.h"
+#include "share.h"
+#include "strerror.h"
+#include "url.h"
+#include "multiif.h"
+#include "inet_pton.h"
+#include "connect.h"
+#include "select.h"
+#include "progress.h"
+
+#define _MPRINTF_REPLACE /* use our functions only */
+#include <curl/mprintf.h>
+
+#  if defined(CURL_STATICLIB) && !defined(CARES_STATICLIB) && \
+     (defined(WIN32) || defined(_WIN32) || defined(__SYMBIAN32__))
+#    define CARES_STATICLIB
+#  endif
+#  include <ares.h>
+
+#if ARES_VERSION >= 0x010500
+/* c-ares 1.5.0 or later, the callback proto is modified */
+#define HAVE_CARES_CALLBACK_TIMEOUTS 1
+#endif
+
+#include "curl_memory.h"
+/* The last #include file should be: */
+#include "memdebug.h"
+
+struct ResolverResults {
+  int num_pending; /* number of ares_gethostbyname() requests */
+  Curl_addrinfo *temp_ai; /* intermediary result while fetching c-ares parts */
+  int last_status;
+};
+
+/*
+ * Curl_resolver_global_init() - the generic low-level asynchronous name
+ * resolve API.  Called from curl_global_init() to initialize global resolver
+ * environment.  Initializes ares library.
+ */
+int Curl_resolver_global_init(void)
+{
+#ifdef CARES_HAVE_ARES_LIBRARY_INIT
+  if(ares_library_init(ARES_LIB_INIT_ALL)) {
+    return CURLE_FAILED_INIT;
+  }
+#endif
+  return CURLE_OK;
+}
+
+/*
+ * Curl_resolver_global_cleanup()
+ *
+ * Called from curl_global_cleanup() to destroy global resolver environment.
+ * Deinitializes ares library.
+ */
+void Curl_resolver_global_cleanup(void)
+{
+#ifdef CARES_HAVE_ARES_LIBRARY_CLEANUP
+  ares_library_cleanup();
+#endif
+}
+
+/*
+ * Curl_resolver_init()
+ *
+ * Called from curl_easy_init() -> Curl_open() to initialize resolver
+ * URL-state specific environment ('resolver' member of the UrlState
+ * structure).  Fills the passed pointer by the initialized ares_channel.
+ */
+int Curl_resolver_init(void **resolver)
+{
+  int status = ares_init((ares_channel*)resolver);
+  if(status != ARES_SUCCESS) {
+    if(status == ARES_ENOMEM)
+      return CURLE_OUT_OF_MEMORY;
+    else
+      return CURLE_FAILED_INIT;
+  }
+  return CURLE_OK;
+  /* make sure that all other returns from this function should destroy the
+     ares channel before returning error! */
+}
+
+/*
+ * Curl_resolver_cleanup()
+ *
+ * Called from curl_easy_cleanup() -> Curl_close() to cleanup resolver
+ * URL-state specific environment ('resolver' member of the UrlState
+ * structure).  Destroys the ares channel.
+ */
+void Curl_resolver_cleanup(void *resolver)
+{
+  ares_destroy((ares_channel)resolver);
+}
+
+/*
+ * Curl_resolver_duphandle()
+ *
+ * Called from curl_easy_duphandle() to duplicate resolver URL-state specific
+ * environment ('resolver' member of the UrlState structure).  Duplicates the
+ * 'from' ares channel and passes the resulting channel to the 'to' pointer.
+ */
+int Curl_resolver_duphandle(void **to, void *from)
+{
+  /* Clone the ares channel for the new handle */
+  if(ARES_SUCCESS != ares_dup((ares_channel*)to,(ares_channel)from))
+    return CURLE_FAILED_INIT;
+  return CURLE_OK;
+}
+
+static void destroy_async_data (struct Curl_async *async);
+
+/*
+ * Cancel all possibly still on-going resolves for this connection.
+ */
+void Curl_resolver_cancel(struct connectdata *conn)
+{
+  if( conn && conn->data && conn->data->state.resolver )
+    ares_cancel((ares_channel)conn->data->state.resolver);
+  destroy_async_data(&conn->async);
+}
+
+/*
+ * destroy_async_data() cleans up async resolver data.
+ */
+static void destroy_async_data (struct Curl_async *async)
+{
+  if(async->hostname)
+    free(async->hostname);
+
+  if(async->os_specific) {
+    struct ResolverResults *res = (struct ResolverResults *)async->os_specific;
+    if( res ) {
+      if( res->temp_ai ) {
+        Curl_freeaddrinfo(res->temp_ai);
+        res->temp_ai = NULL;
+      }
+      free(res);
+    }
+    async->os_specific = NULL;
+  }
+
+  async->hostname = NULL;
+}
+
+/*
+ * Curl_resolver_fdset() is called when someone from the outside world (using
+ * curl_multi_fdset()) wants to get our fd_set setup and we're talking with
+ * ares. The caller must make sure that this function is only called when we
+ * have a working ares channel.
+ *
+ * Returns: CURLE_OK always!
+ */
+
+int Curl_resolver_getsock(struct connectdata *conn,
+                          curl_socket_t *socks,
+                          int numsocks)
+
+{
+  struct timeval maxtime;
+  struct timeval timebuf;
+  struct timeval *timeout;
+  int max = ares_getsock((ares_channel)conn->data->state.resolver,
+                         (ares_socket_t *)socks, numsocks);
+
+
+  maxtime.tv_sec = CURL_TIMEOUT_RESOLVE;
+  maxtime.tv_usec = 0;
+
+  timeout = ares_timeout((ares_channel)conn->data->state.resolver, &maxtime,
+                         &timebuf);
+
+  Curl_expire(conn->data,
+              (timeout->tv_sec * 1000) + (timeout->tv_usec/1000));
+
+  return max;
+}
+
+/*
+ * waitperform()
+ *
+ * 1) Ask ares what sockets it currently plays with, then
+ * 2) wait for the timeout period to check for action on ares' sockets.
+ * 3) tell ares to act on all the sockets marked as "with action"
+ *
+ * return number of sockets it worked on
+ */
+
+static int waitperform(struct connectdata *conn, int timeout_ms)
+{
+  struct SessionHandle *data = conn->data;
+  int nfds;
+  int bitmask;
+  ares_socket_t socks[ARES_GETSOCK_MAXNUM];
+  struct pollfd pfd[ARES_GETSOCK_MAXNUM];
+  int i;
+  int num = 0;
+
+  bitmask = ares_getsock((ares_channel)data->state.resolver, socks,
+                         ARES_GETSOCK_MAXNUM);
+
+  for(i=0; i < ARES_GETSOCK_MAXNUM; i++) {
+    pfd[i].events = 0;
+    pfd[i].revents = 0;
+    if(ARES_GETSOCK_READABLE(bitmask, i)) {
+      pfd[i].fd = socks[i];
+      pfd[i].events |= POLLRDNORM|POLLIN;
+    }
+    if(ARES_GETSOCK_WRITABLE(bitmask, i)) {
+      pfd[i].fd = socks[i];
+      pfd[i].events |= POLLWRNORM|POLLOUT;
+    }
+    if(pfd[i].events != 0)
+      num++;
+    else
+      break;
+  }
+
+  if(num)
+    nfds = Curl_poll(pfd, num, timeout_ms);
+  else
+    nfds = 0;
+
+  if(!nfds)
+    /* Call ares_process() unconditonally here, even if we simply timed out
+       above, as otherwise the ares name resolve won't timeout! */
+    ares_process_fd((ares_channel)data->state.resolver, ARES_SOCKET_BAD,
+                    ARES_SOCKET_BAD);
+  else {
+    /* move through the descriptors and ask for processing on them */
+    for(i=0; i < num; i++)
+      ares_process_fd((ares_channel)data->state.resolver,
+                      pfd[i].revents & (POLLRDNORM|POLLIN)?
+                      pfd[i].fd:ARES_SOCKET_BAD,
+                      pfd[i].revents & (POLLWRNORM|POLLOUT)?
+                      pfd[i].fd:ARES_SOCKET_BAD);
+  }
+  return nfds;
+}
+
+/*
+ * Curl_resolver_is_resolved() is called repeatedly to check if a previous
+ * name resolve request has completed. It should also make sure to time-out if
+ * the operation seems to take too long.
+ *
+ * Returns normal CURLcode errors.
+ */
+CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
+                                   struct Curl_dns_entry **dns)
+{
+  struct SessionHandle *data = conn->data;
+  struct ResolverResults *res = (struct ResolverResults *)
+    conn->async.os_specific;
+
+  *dns = NULL;
+
+  waitperform(conn, 0);
+
+  if( res && !res->num_pending ) {
+    (void)Curl_addrinfo_callback(conn, res->last_status, res->temp_ai);
+    /* temp_ai ownership is moved to the connection, so we need not free-up
+       them */
+    res->temp_ai = NULL;
+    destroy_async_data(&conn->async);
+    if(!conn->async.dns) {
+      failf(data, "Could not resolve host: %s (%s)", conn->host.dispname,
+            ares_strerror(conn->async.status));
+      return CURLE_COULDNT_RESOLVE_HOST;
+    }
+    *dns = conn->async.dns;
+  }
+
+  return CURLE_OK;
+}
+
+/*
+ * Curl_resolver_wait_resolv()
+ *
+ * waits for a resolve to finish. This function should be avoided since using
+ * this risk getting the multi interface to "hang".
+ *
+ * If 'entry' is non-NULL, make it point to the resolved dns entry
+ *
+ * Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved, and
+ * CURLE_OPERATION_TIMEDOUT if a time-out occurred.
+ */
+CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
+                                   struct Curl_dns_entry **entry)
+{
+  CURLcode rc=CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  long timeout;
+  struct timeval now = Curl_tvnow();
+  struct Curl_dns_entry *temp_entry;
+
+  timeout = Curl_timeleft(data, &now, TRUE);
+  if(!timeout)
+    timeout = CURL_TIMEOUT_RESOLVE * 1000; /* default name resolve timeout */
+
+  /* Wait for the name resolve query to complete. */
+  for(;;) {
+    struct timeval *tvp, tv, store;
+    long timediff;
+    int itimeout;
+    int timeout_ms;
+
+    itimeout = (timeout > (long)INT_MAX) ? INT_MAX : (int)timeout;
+
+    store.tv_sec = itimeout/1000;
+    store.tv_usec = (itimeout%1000)*1000;
+
+    tvp = ares_timeout((ares_channel)data->state.resolver, &store, &tv);
+
+    /* use the timeout period ares returned to us above if less than one
+       second is left, otherwise just use 1000ms to make sure the progress
+       callback gets called frequent enough */
+    if(!tvp->tv_sec)
+      timeout_ms = (int)(tvp->tv_usec/1000);
+    else
+      timeout_ms = 1000;
+
+    waitperform(conn, timeout_ms);
+    Curl_resolver_is_resolved(conn,&temp_entry);
+
+    if(conn->async.done)
+      break;
+
+    if(Curl_pgrsUpdate(conn)) {
+      rc = CURLE_ABORTED_BY_CALLBACK;
+      timeout = -1; /* trigger the cancel below */
+    }
+    else {
+      struct timeval now2 = Curl_tvnow();
+      timediff = Curl_tvdiff(now2, now); /* spent time */
+      timeout -= timediff?timediff:1; /* always deduct at least 1 */
+      now = now2; /* for next loop */
+    }
+    if(timeout < 0) {
+      /* our timeout, so we cancel the ares operation */
+      ares_cancel((ares_channel)data->state.resolver);
+      break;
+    }
+  }
+
+  /* Operation complete, if the lookup was successful we now have the entry
+     in the cache. */
+
+  if(entry)
+    *entry = conn->async.dns;
+
+  if(!conn->async.dns) {
+    /* a name was not resolved */
+    if((timeout < 0) || (conn->async.status == ARES_ETIMEOUT)) {
+      if (conn->bits.httpproxy) {
+        failf(data, "Resolving proxy timed out: %s", conn->proxy.dispname);
+        rc = CURLE_COULDNT_RESOLVE_PROXY;
+      }
+      else {
+        failf(data, "Resolving host timed out: %s", conn->host.dispname);
+        rc = CURLE_COULDNT_RESOLVE_HOST;
+      }
+    }
+    else if(conn->async.done) {
+      if (conn->bits.httpproxy) {
+        failf(data, "Could not resolve proxy: %s (%s)", conn->proxy.dispname,
+              ares_strerror(conn->async.status));
+        rc = CURLE_COULDNT_RESOLVE_PROXY;
+      }
+      else {
+        failf(data, "Could not resolve host: %s (%s)", conn->host.dispname,
+              ares_strerror(conn->async.status));
+        rc = CURLE_COULDNT_RESOLVE_HOST;
+      }
+    }
+    else
+      rc = CURLE_OPERATION_TIMEDOUT;
+
+    /* close the connection, since we can't return failure here without
+       cleaning up this connection properly */
+    conn->bits.close = TRUE;
+  }
+
+  return rc;
+}
+
+/* Connects results to the list */
+static void compound_results(struct ResolverResults *res,
+                             Curl_addrinfo *ai)
+{
+  Curl_addrinfo *ai_tail;
+  if(!ai)
+    return;
+  ai_tail = ai;
+
+  while (ai_tail->ai_next)
+    ai_tail = ai_tail->ai_next;
+
+  /* Add the new results to the list of old results. */
+  ai_tail->ai_next = res->temp_ai;
+  res->temp_ai = ai;
+}
+
+/*
+ * ares_query_completed_cb() is the callback that ares will call when
+ * the host query initiated by ares_gethostbyname() from Curl_getaddrinfo(),
+ * when using ares, is completed either successfully or with failure.
+ */
+static void query_completed_cb(void *arg,  /* (struct connectdata *) */
+                               int status,
+#ifdef HAVE_CARES_CALLBACK_TIMEOUTS
+                               int timeouts,
+#endif
+                               struct hostent *hostent)
+{
+  struct connectdata *conn = (struct connectdata *)arg;
+  struct ResolverResults *res;
+
+#ifdef HAVE_CARES_CALLBACK_TIMEOUTS
+  (void)timeouts; /* ignored */
+#endif
+
+  if(ARES_EDESTRUCTION == status)
+    /* when this ares handle is getting destroyed, the 'arg' pointer may not
+       be valid so only defer it when we know the 'status' says its fine! */
+    return;
+
+  res = (struct ResolverResults *)conn->async.os_specific;
+  res->num_pending--;
+
+  if(CURL_ASYNC_SUCCESS == status) {
+    Curl_addrinfo *ai = Curl_he2ai(hostent, conn->async.port);
+    if(ai) {
+      compound_results(res, ai);
+    }
+  }
+  /* A successful result overwrites any previous error */
+  if( res->last_status != ARES_SUCCESS )
+    res->last_status = status;
+}
+
+/*
+ * Curl_resolver_getaddrinfo() - when using ares
+ *
+ * Returns name information about the given hostname and port number. If
+ * successful, the 'hostent' is returned and the forth argument will point to
+ * memory we need to free after use. That memory *MUST* be freed with
+ * Curl_freeaddrinfo(), nothing else.
+ */
+Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
+                                         const char *hostname,
+                                         int port,
+                                         int *waitp)
+{
+  char *bufp;
+  struct SessionHandle *data = conn->data;
+  struct in_addr in;
+  int family = PF_INET;
+#ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
+  struct in6_addr in6;
+#endif /* CURLRES_IPV6 */
+
+  *waitp = 0; /* default to synchronous response */
+
+  /* First check if this is an IPv4 address string */
+  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);
+  }
+
+#ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
+  /* Otherwise, check if this is an IPv6 address string */
+  if (Curl_inet_pton (AF_INET6, hostname, &in6) > 0) {
+    /* This must be an IPv6 address literal.  */
+    return Curl_ip2addr(AF_INET6, &in6, hostname, port);
+  }
+
+  switch(conn->ip_version) {
+  default:
+#if ARES_VERSION >= 0x010601
+    family = PF_UNSPEC; /* supported by c-ares since 1.6.1, so for older
+                           c-ares versions this just falls through and defaults
+                           to PF_INET */
+    break;
+#endif
+  case CURL_IPRESOLVE_V4:
+    family = PF_INET;
+    break;
+  case CURL_IPRESOLVE_V6:
+    family = PF_INET6;
+    break;
+  }
+#endif /* CURLRES_IPV6 */
+
+  bufp = strdup(hostname);
+  if(bufp) {
+    struct ResolverResults *res = NULL;
+    Curl_safefree(conn->async.hostname);
+    conn->async.hostname = bufp;
+    conn->async.port = port;
+    conn->async.done = FALSE;   /* not done */
+    conn->async.status = 0;     /* clear */
+    conn->async.dns = NULL;     /* clear */
+    res = (struct ResolverResults *)calloc(sizeof(struct ResolverResults),1);
+    if( !res ) {
+      Curl_safefree(conn->async.hostname);
+      conn->async.hostname = NULL;
+      return NULL;
+    }
+    conn->async.os_specific = res;
+
+    /* initial status - failed */
+    res->last_status = ARES_ENOTFOUND;
+#ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
+    if(family == PF_UNSPEC) {
+      res->num_pending = 2;
+
+      /* areschannel is already setup in the Curl_open() function */
+      ares_gethostbyname((ares_channel)data->state.resolver, hostname, PF_INET,
+                         query_completed_cb, conn);
+      ares_gethostbyname((ares_channel)data->state.resolver, hostname, PF_INET6,
+                         query_completed_cb, conn);
+    }
+    else
+#endif /* CURLRES_IPV6 */
+    {
+      res->num_pending = 1;
+
+      /* areschannel is already setup in the Curl_open() function */
+      ares_gethostbyname((ares_channel)data->state.resolver, hostname, family,
+                         query_completed_cb, conn);
+    }
+
+    *waitp = 1; /* expect asynchronous response */
+  }
+  return NULL; /* no struct yet */
+}
+#endif /* CURLRES_ARES */