moving resolver to util, making DNS lookups asynchronous in util

1 files changed, 589 insertions, 0 deletions

diff --git a/src/util/resolver_api.c b/src/util/resolver_api.c
new file mode 100644
index 000000000..dcda3141e
--- /dev/null
+++ b/src/util/resolver_api.c
@@ -0,0 +1,589 @@
+/*
+     This file is part of GNUnet.
+     (C) 2009 Christian Grothoff (and other contributing authors)
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 2, or (at your
+     option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+
+/**
+ * @file resolver/resolver_api.c
+ * @brief resolver for writing a tool
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "gnunet_getopt_lib.h"
+#include "gnunet_client_lib.h"
+#include "gnunet_protocols.h"
+#include "gnunet_resolver_service.h"
+#include "gnunet_server_lib.h"
+#include "resolver.h"
+
+
+/**
+ * FIXME.
+ */
+struct GetAddressContext
+{
+
+  /**
+   * FIXME.
+   */
+  GNUNET_RESOLVER_AddressCallback callback;
+
+  /**
+   * Closure for "callback".
+   */
+  void *cls;
+
+  /**
+   * FIXME.
+   */
+  struct GNUNET_RESOLVER_GetMessage *msg;
+
+  /**
+   * FIXME.
+   */
+  struct GNUNET_CLIENT_Connection *client;
+
+  /**
+   * FIXME.
+   */
+  struct GNUNET_TIME_Absolute timeout;
+};
+
+
+/**
+ * Possible hostnames for "loopback".
+ */
+static const char *loopback[] = {
+  "localhost",
+  "127.0.0.1",
+  "ip6-localnet",
+  "::1",
+  NULL
+};
+
+
+/**
+ * Check that the resolver service runs on localhost
+ * (or equivalent).
+ */
+static void
+check_config (const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  char *hostname;
+  unsigned int i;
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_string (cfg,
+                                             "resolver",
+                                             "HOSTNAME",
+                                             &hostname))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  _("Must specify `%s' for `%s' in configuration!\n"),
+                  "HOSTNAME",
+                  "resolver");
+      GNUNET_assert (0);
+    }
+  i = 0;
+  while (loopback[i] != NULL)
+    if (0 == strcmp (loopback[i++], hostname))
+      {
+        GNUNET_free (hostname); 
+        return;
+      }
+  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+              _("Must specify `%s' for `%s' in configuration!\n"),
+              "localhost",
+              "resolver");
+  GNUNET_free (hostname); 
+  GNUNET_assert (0); 
+}
+
+
+/**
+ * Convert IP address to string without DNS resolution.
+ */
+static char *
+no_resolve (const struct sockaddr *sa, socklen_t salen)
+{
+  char *ret;
+  char inet4[INET_ADDRSTRLEN];
+  char inet6[INET6_ADDRSTRLEN];
+
+  if (salen < sizeof (struct sockaddr))
+    return NULL;
+  switch (sa->sa_family)
+    {
+    case AF_INET:
+      if (salen != sizeof (struct sockaddr_in))
+        return NULL;
+      inet_ntop (AF_INET,
+                 &((struct sockaddr_in *) sa)->sin_addr,
+                 inet4, INET_ADDRSTRLEN);
+      ret = GNUNET_strdup (inet4);
+      break;
+    case AF_INET6:
+      if (salen != sizeof (struct sockaddr_in6))
+        return NULL;
+      inet_ntop (AF_INET6,
+                 &((struct sockaddr_in6 *) sa)->sin6_addr,
+                 inet6, INET6_ADDRSTRLEN);
+      ret = GNUNET_strdup (inet6);
+      break;
+    default:
+      ret = NULL;
+      break;
+    }
+  return ret;
+}
+
+
+static void
+handle_address_response (void *cls, const struct GNUNET_MessageHeader *msg)
+{
+  struct GetAddressContext *gac = cls;
+  uint16_t size;
+  const struct sockaddr *sa;
+  socklen_t salen;
+
+
+  if (msg == NULL)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  _("Timeout trying to resolve hostname.\n"));
+      gac->callback (gac->cls, NULL, 0);
+      GNUNET_CLIENT_disconnect (gac->client);
+      GNUNET_free (gac);
+      return;
+    }
+  if (GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE != ntohs (msg->type))
+    {
+      GNUNET_break (0);
+      gac->callback (gac->cls, NULL, 0);
+      GNUNET_CLIENT_disconnect (gac->client);
+      GNUNET_free (gac);
+      return;
+    }
+
+  size = ntohs (msg->size);
+  if (size == sizeof (struct GNUNET_MessageHeader))
+    {
+#if DEBUG_RESOLVER
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  _("Received end message resolving hostname.\n"));
+#endif
+      gac->callback (gac->cls, NULL, 0);
+      GNUNET_CLIENT_disconnect (gac->client);
+      GNUNET_free (gac);
+      return;
+    }
+  sa = (const struct sockaddr *) &msg[1];
+  salen = size - sizeof (struct GNUNET_MessageHeader);
+  if (salen < sizeof (struct sockaddr))
+    {
+      GNUNET_break (0);
+      gac->callback (gac->cls, NULL, 0);
+      GNUNET_CLIENT_disconnect (gac->client);
+      GNUNET_free (gac);
+      return;
+    }
+#if DEBUG_RESOLVER
+  {
+    char *ips = no_resolve (sa, salen);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _("Resolver returns `%s'.\n"), ips);
+    GNUNET_free (ips);
+  }
+#endif
+  gac->callback (gac->cls, sa, salen);
+  GNUNET_CLIENT_receive (gac->client,
+                         &handle_address_response,
+                         gac,
+                         GNUNET_TIME_absolute_get_remaining (gac->timeout));
+}
+
+
+static size_t
+transmit_get_ip (void *cls, size_t size, void *buf)
+{
+  struct GetAddressContext *actx = cls;
+  uint16_t ms;
+
+  if (buf == NULL)
+    {
+      /* timeout / error */
+      GNUNET_free (actx->msg);
+      actx->callback (actx->cls, NULL, 0);
+      GNUNET_CLIENT_disconnect (actx->client);
+      GNUNET_free (actx);
+      return 0;
+    }
+  ms = ntohs (actx->msg->header.size);
+  GNUNET_assert (size >= ms);
+  memcpy (buf, actx->msg, ms);
+  GNUNET_free (actx->msg);
+  actx->msg = NULL;
+  GNUNET_CLIENT_receive (actx->client,
+                         &handle_address_response,
+                         actx,
+                         GNUNET_TIME_absolute_get_remaining (actx->timeout));
+  return ms;
+}
+
+
+
+/**
+ * Convert a string to one or more IP addresses.
+ *
+ * @param sched scheduler to use
+ * @param cfg configuration to use
+ * @param hostname the hostname to resolve
+ * @param domain AF_INET or AF_INET6; use AF_UNSPEC for "any"
+ * @param callback function to call with addresses
+ * @param callback_cls closure for callback
+ * @param timeout how long to try resolving
+ */
+void
+GNUNET_RESOLVER_ip_get (struct GNUNET_SCHEDULER_Handle *sched,
+                        const struct GNUNET_CONFIGURATION_Handle *cfg,
+                        const char *hostname,
+                        int domain,
+                        struct GNUNET_TIME_Relative timeout,
+                        GNUNET_RESOLVER_AddressCallback callback, 
+                        void *callback_cls)
+{
+  struct GNUNET_CLIENT_Connection *client;
+  struct GNUNET_RESOLVER_GetMessage *msg;
+  struct GetAddressContext *actx;
+  size_t slen;
+  unsigned int i;
+  struct sockaddr_in v4;
+  struct sockaddr_in6 v6;
+
+  check_config (cfg);
+  i = 0;
+  while (loopback[i] != NULL)
+    if (0 == strcmp (loopback[i++], hostname))
+      {
+        memset (&v4, 0, sizeof(v4));
+#if HAVE_SOCKADDR_IN_SIN_LEN
+        v4.sin_len = sizeof (v4);
+#endif
+        v4.sin_family = AF_INET;
+        v4.sin_addr.s_addr = htonl (INADDR_LOOPBACK);  
+
+        memset (&v6, 0, sizeof(v6));
+#if HAVE_SOCKADDR_IN_SIN_LEN
+        v6.sin6_len = sizeof (v6);
+#endif
+        v6.sin6_family = AF_INET6;
+        v6.sin6_addr = in6addr_loopback;
+
+        switch (domain)
+          {
+          case AF_INET:
+            callback (callback_cls, 
+                      (const struct sockaddr*) &v4,
+                      sizeof(v4));
+            break;
+          case AF_INET6:
+            callback (callback_cls, 
+                      (const struct sockaddr*) &v6,
+                      sizeof(v6));
+            break;
+          case AF_UNSPEC:
+            callback (callback_cls, 
+                      (const struct sockaddr*) &v4,
+                      sizeof(v4));
+            callback (callback_cls, 
+                      (const struct sockaddr*) &v6,
+                      sizeof(v6));
+            break;
+          }
+        callback (callback_cls, NULL, 0);
+        return;
+      }
+  slen = strlen (hostname) + 1;
+  if (slen + sizeof (struct GNUNET_RESOLVER_GetMessage) >
+      GNUNET_SERVER_MAX_MESSAGE_SIZE)
+    {
+      GNUNET_break (0);
+      callback (callback_cls, NULL, 0);
+      return;
+    }
+  client = GNUNET_CLIENT_connect (sched, "resolver", cfg);
+  if (client == NULL)
+    {
+      callback (callback_cls, NULL, 0);
+      return;
+    }
+  msg = GNUNET_malloc (sizeof (struct GNUNET_RESOLVER_GetMessage) + slen);
+  msg->header.size =
+    htons (sizeof (struct GNUNET_RESOLVER_GetMessage) + slen);
+  msg->header.type = htons (GNUNET_MESSAGE_TYPE_RESOLVER_REQUEST);
+  msg->direction = htonl (GNUNET_NO);
+  msg->domain = htonl (domain);
+  memcpy (&msg[1], hostname, slen);
+  actx = GNUNET_malloc (sizeof (struct GetAddressContext));
+  actx->callback = callback;
+  actx->cls = callback_cls;
+  actx->client = client;
+  actx->timeout = GNUNET_TIME_relative_to_absolute (timeout);
+  actx->msg = msg;
+
+#if DEBUG_RESOLVER
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              _("Resolver requests DNS resolution of hostname `%s'.\n"),
+              hostname);
+#endif
+  if (NULL ==
+      GNUNET_CLIENT_notify_transmit_ready (client,
+                                           slen +
+                                           sizeof (struct
+                                                   GNUNET_RESOLVER_GetMessage),
+                                           timeout, &transmit_get_ip, actx))
+    {
+      GNUNET_free (msg);
+      GNUNET_free (actx);
+      callback (callback_cls, NULL, 0);
+      GNUNET_CLIENT_disconnect (client);
+      return;
+    }
+}
+
+
+struct GetHostnameContext
+{
+  GNUNET_RESOLVER_HostnameCallback callback;
+  void *cls;
+  struct GNUNET_RESOLVER_GetMessage *msg;
+  struct GNUNET_CLIENT_Connection *client;
+  struct GNUNET_TIME_Absolute timeout;
+};
+
+
+static void
+handle_hostname_response (void *cls, const struct GNUNET_MessageHeader *msg)
+{
+  struct GetHostnameContext *ghc = cls;
+  uint16_t size;
+  const char *hostname;
+
+  if (msg == NULL)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  _("Timeout trying to resolve IP address.\n"));
+      ghc->callback (ghc->cls, NULL);
+      GNUNET_CLIENT_disconnect (ghc->client);
+      GNUNET_free (ghc);
+      return;
+    }
+  size = ntohs (msg->size);
+  if (size == sizeof (struct GNUNET_MessageHeader))
+    {
+#if DEBUG_RESOLVER
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  _("Received end message resolving IP address.\n"));
+#endif
+      ghc->callback (ghc->cls, NULL);
+      GNUNET_CLIENT_disconnect (ghc->client);
+      GNUNET_free (ghc);
+      return;
+    }
+  hostname = (const char *) &msg[1];
+  if (hostname[size - sizeof (struct GNUNET_MessageHeader) - 1] != '\0')
+    {
+      GNUNET_break (0);
+      ghc->callback (ghc->cls, NULL);
+      GNUNET_CLIENT_disconnect (ghc->client);
+      GNUNET_free (ghc);
+      return;
+    }
+#if DEBUG_RESOLVER
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              _("Resolver returns `%s'.\n"), hostname);
+#endif
+  ghc->callback (ghc->cls, hostname);
+  GNUNET_CLIENT_receive (ghc->client,
+                         &handle_hostname_response,
+                         ghc,
+                         GNUNET_TIME_absolute_get_remaining (ghc->timeout));
+}
+
+
+static size_t
+transmit_get_hostname (void *cls, size_t size, void *buf)
+{
+  struct GetHostnameContext *hctx = cls;
+  uint16_t msize;
+
+  if (buf == NULL)
+    {
+      GNUNET_free (hctx->msg);
+      hctx->callback (hctx->cls, NULL);
+      GNUNET_CLIENT_disconnect (hctx->client);
+      GNUNET_free (hctx);
+      return 0;
+    }
+  msize = ntohs (hctx->msg->header.size);
+  GNUNET_assert (size >= msize);
+  memcpy (buf, hctx->msg, msize);
+  GNUNET_free (hctx->msg);
+  hctx->msg = NULL;
+  GNUNET_CLIENT_receive (hctx->client,
+                         &handle_hostname_response,
+                         hctx,
+                         GNUNET_TIME_absolute_get_remaining (hctx->timeout));
+  return msize;
+}
+
+
+
+
+/**
+ * Get an IP address as a string.
+ *
+ * @param sched scheduler to use
+ * @param cfg configuration to use
+ * @param sa host address
+ * @param salen length of host address
+ * @param do_resolve use GNUNET_NO to return numeric hostname
+ * @param timeout how long to try resolving
+ * @param callback function to call with hostnames
+ * @param cls closure for callback
+ */
+void
+GNUNET_RESOLVER_hostname_get (struct GNUNET_SCHEDULER_Handle *sched,
+                              const struct GNUNET_CONFIGURATION_Handle *cfg,
+                              const struct sockaddr *sa,
+                              socklen_t salen,
+                              int do_resolve,
+                              struct GNUNET_TIME_Relative timeout,
+                              GNUNET_RESOLVER_HostnameCallback callback,
+                              void *cls)
+{
+  char *result;
+  struct GNUNET_CLIENT_Connection *client;
+  struct GNUNET_RESOLVER_GetMessage *msg;
+  struct GetHostnameContext *hctx;
+
+  check_config (cfg);
+  if (GNUNET_NO == do_resolve)
+    {
+      result = no_resolve (sa, salen);
+#if DEBUG_RESOLVER
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  _("Resolver returns `%s'.\n"), result);
+#endif
+      callback (cls, result);
+      if (result != NULL)
+        {
+          GNUNET_free (result);
+          callback (cls, NULL);
+        }
+      return;
+    }
+  if (salen + sizeof (struct GNUNET_RESOLVER_GetMessage) >
+      GNUNET_SERVER_MAX_MESSAGE_SIZE)
+    {
+      GNUNET_break (0);
+      callback (cls, NULL);
+      return;
+    }
+  client = GNUNET_CLIENT_connect (sched, "resolver", cfg);
+  if (client == NULL)
+    {
+      callback (cls, NULL);
+      return;
+    }
+  msg = GNUNET_malloc (sizeof (struct GNUNET_RESOLVER_GetMessage) + salen);
+  msg->header.size =
+    htons (sizeof (struct GNUNET_RESOLVER_GetMessage) + salen);
+  msg->header.type = htons (GNUNET_MESSAGE_TYPE_RESOLVER_REQUEST);
+  msg->direction = htonl (GNUNET_YES);
+  msg->domain = htonl (sa->sa_family);
+  memcpy (&msg[1], sa, salen);
+#if DEBUG_RESOLVER
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              _("Resolver requests DNS resolution of IP address.\n"));
+#endif
+  hctx = GNUNET_malloc (sizeof (struct GetHostnameContext));
+  hctx->callback = callback;
+  hctx->cls = cls;
+  hctx->client = client;
+  hctx->timeout = GNUNET_TIME_relative_to_absolute (timeout);
+  hctx->msg = msg;
+  if (NULL ==
+      GNUNET_CLIENT_notify_transmit_ready (client,
+                                           sizeof (struct
+                                                   GNUNET_RESOLVER_GetMessage)
+                                           + salen, timeout,
+                                           &transmit_get_hostname, hctx))
+    {
+      GNUNET_free (msg);
+      callback (cls, NULL);
+      GNUNET_CLIENT_disconnect (client);
+      GNUNET_free (hctx);
+    }
+}
+
+/**
+ * Maximum supported length of hostname
+ */
+#define MAX_HOSTNAME 1024
+
+
+/**
+ * Resolve our hostname to an IP address.
+ *
+ * @param sched scheduler to use
+ * @param cfg configuration to use
+ * @param domain AF_INET or AF_INET6; use AF_UNSPEC for "any"
+ * @param callback function to call with addresses
+ * @param cls closure for callback
+ * @param timeout how long to try resolving
+ */
+void
+GNUNET_RESOLVER_hostname_resolve (struct GNUNET_SCHEDULER_Handle *sched,
+                                  const struct GNUNET_CONFIGURATION_Handle *cfg,
+                                  int domain,
+                                  struct GNUNET_TIME_Relative timeout,
+                                  GNUNET_RESOLVER_AddressCallback callback,
+                                  void *cls)
+{
+  char hostname[MAX_HOSTNAME];
+
+  check_config (cfg);
+  if (0 != gethostname (hostname, sizeof (hostname) - 1))
+    {
+      GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR |
+                           GNUNET_ERROR_TYPE_BULK, "gethostname");
+      callback (cls, NULL, 0);
+      return;
+    }
+#if DEBUG_RESOLVER
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              _("Resolving our hostname `%s'\n"), hostname);
+#endif
+  GNUNET_RESOLVER_ip_get (sched,
+                          cfg, hostname, domain, timeout, callback, cls);
+}
+
+
+
+
+/* end of resolver_api.c */