moving resolver to util, making DNS lookups asynchronous in util

1 files changed, 492 insertions, 0 deletions

diff --git a/src/util/gnunet-service-resolver.c b/src/util/gnunet-service-resolver.c
new file mode 100644
index 000000000..304f11b7b
--- /dev/null
+++ b/src/util/gnunet-service-resolver.c
@@ -0,0 +1,492 @@
+/*
+     This file is part of GNUnet.
+     (C) 2007, 2008, 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/gnunet-service-resolver.c
+ * @brief code to do DNS resolution
+ * @author Christian Grothoff
+ */
+
+#include <stdlib.h>
+#include "platform.h"
+#include "gnunet_disk_lib.h"
+#include "gnunet_getopt_lib.h"
+#include "gnunet_protocols.h"
+#include "gnunet_service_lib.h"
+#include "gnunet_statistics_service.h"
+#include "gnunet_strings_lib.h"
+#include "gnunet_time_lib.h"
+#include "resolver.h"
+
+
+struct IPCache
+{
+  struct IPCache *next;
+  char *addr;
+  struct sockaddr *sa;
+  struct GNUNET_TIME_Absolute last_refresh;
+  struct GNUNET_TIME_Absolute last_request;
+  unsigned int salen;
+};
+
+
+static struct IPCache *head;
+
+
+
+
+#if HAVE_GETNAMEINFO
+static void
+getnameinfo_resolve (struct IPCache *cache)
+{
+  char hostname[256];
+
+  if (0 == getnameinfo (cache->sa, 
+                        cache->salen, 
+                        hostname, 
+                        sizeof(hostname), 
+                        NULL, 0, 0))
+    cache->addr = GNUNET_strdup (hostname);
+}
+#endif
+
+
+#if HAVE_GETHOSTBYADDR
+static void
+gethostbyaddr_resolve (struct IPCache *cache)
+{
+  struct hostent *ent;
+
+  switch (cache->sa->sa_family)
+    {
+    case AF_INET:
+      ent = gethostbyaddr (&((struct sockaddr_in *) cache->sa)->sin_addr,
+                           sizeof (struct in_addr), AF_INET);
+      break;
+    case AF_INET6:
+      ent = gethostbyaddr (&((struct sockaddr_in6 *) cache->sa)->sin6_addr,
+                           sizeof (struct in6_addr), AF_INET6);
+      break;
+    default:
+      ent = NULL;
+    }
+  if (ent != NULL)
+    cache->addr = GNUNET_strdup (ent->h_name);
+}
+#endif
+
+
+static void
+cache_resolve (struct IPCache *cache)
+{
+#if HAVE_GETNAMEINFO
+  if (cache->addr == NULL)
+    getnameinfo_resolve (cache);
+#endif
+#if HAVE_GETHOSTBYADDR
+  if (cache->addr == NULL)
+    gethostbyaddr_resolve (cache);
+#endif
+}
+
+
+
+/**
+ * Get an IP address as a string (works for both IPv4 and IPv6).  Note
+ * that the resolution happens asynchronously and that the first call
+ * may not immediately result in the FQN (but instead in a
+ * human-readable IP address).
+ *
+ * @param sa should be of type "struct sockaddr*"
+ */
+static void
+get_ip_as_string (struct GNUNET_SERVER_Client *client,
+                  const struct sockaddr *sav, socklen_t salen)
+{
+  struct IPCache *cache;
+  struct IPCache *prev;
+  struct GNUNET_TIME_Absolute now;
+  struct GNUNET_SERVER_TransmitContext *tc;
+
+  if (salen < sizeof (struct sockaddr))
+    {
+      GNUNET_break (0);
+      return;
+    }
+  now = GNUNET_TIME_absolute_get ();
+  cache = head;
+  prev = NULL;
+  while ((cache != NULL) &&
+         ((cache->salen != salen) || (0 != memcmp (cache->sa, sav, salen))))
+    {
+      if (GNUNET_TIME_absolute_get_duration (cache->last_request).value <
+          60 * 60 * 1000)
+        {
+          if (prev != NULL)
+            {
+              prev->next = cache->next;
+              GNUNET_free_non_null (cache->addr);
+              GNUNET_free (cache->sa);
+              GNUNET_free (cache);
+              cache = prev->next;
+            }
+          else
+            {
+              head = cache->next;
+              GNUNET_free_non_null (cache->addr);
+              GNUNET_free (cache->sa);
+              GNUNET_free (cache);
+              cache = head;
+            }
+          continue;
+        }
+      prev = cache;
+      cache = cache->next;
+    }
+  if (cache != NULL)
+    {
+      cache->last_request = now;
+      if (GNUNET_TIME_absolute_get_duration (cache->last_request).value <
+          60 * 60 * 1000)
+        {
+          GNUNET_free_non_null (cache->addr);
+          cache->addr = NULL;
+          cache->salen = 0;
+          cache_resolve (cache);
+        }
+    }
+  else
+    {
+      cache = GNUNET_malloc (sizeof (struct IPCache));
+      cache->next = head;
+      cache->salen = salen;
+      cache->sa = GNUNET_malloc (salen);
+      memcpy (cache->sa, sav, salen);
+      cache->last_request = GNUNET_TIME_absolute_get ();
+      cache->last_refresh = GNUNET_TIME_absolute_get ();
+      cache->addr = NULL;
+      cache_resolve (cache);
+      head = cache;
+    }
+  tc = GNUNET_SERVER_transmit_context_create (client);
+  if (cache->addr != NULL)
+    GNUNET_SERVER_transmit_context_append (tc,
+                                           cache->addr,
+                                           strlen (cache->addr) + 1,
+                                           GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
+  GNUNET_SERVER_transmit_context_append (tc, NULL, 0,
+                                         GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
+  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
+}
+
+
+#if HAVE_GETADDRINFO
+static int
+getaddrinfo_resolve (struct GNUNET_SERVER_TransmitContext *tc,
+                     const char *hostname, int domain)
+{
+  int s;
+  struct addrinfo hints;
+  struct addrinfo *result;
+  struct addrinfo *pos;
+
+  memset (&hints, 0, sizeof (struct addrinfo));
+// FIXME in PlibC
+#ifndef MINGW
+  hints.ai_family = domain;
+#else
+  hints.ai_family = AF_INET;
+#endif
+  hints.ai_socktype = SOCK_STREAM;      /* go for TCP */
+
+  if (0 != (s = getaddrinfo (hostname, NULL, &hints, &result)))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  _("Could not resolve `%s' (%s): %s\n"), hostname,
+                  (domain ==
+                   AF_INET) ? "IPv4" : ((domain ==
+                                         AF_INET6) ? "IPv6" : "any"),
+                  gai_strerror (s));
+      if ((s == EAI_BADFLAGS) || (s == EAI_MEMORY) ||
+#ifndef MINGW
+          (s == EAI_SYSTEM)
+#else
+          // FIXME NILS
+          1
+#endif
+      )
+        return GNUNET_NO;       /* other function may still succeed */
+      return GNUNET_SYSERR;
+    }
+  if (result == NULL)
+    return GNUNET_SYSERR;
+  pos = result;
+  while (pos != NULL)
+    {
+      GNUNET_SERVER_transmit_context_append (tc,
+                                             result->ai_addr,
+                                             result->ai_addrlen,
+                                             GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
+      pos = pos->ai_next;
+    }
+  freeaddrinfo (result);
+  return GNUNET_OK;
+}
+#endif
+
+#if HAVE_GETHOSTBYNAME2
+static int
+gethostbyname2_resolve (struct GNUNET_SERVER_TransmitContext *tc,
+                        const char *hostname, int domain)
+{
+  struct hostent *hp;
+  struct sockaddr_in a4;
+  struct sockaddr_in6 a6;
+  int ret1;
+  int ret2;
+
+  if (domain == AF_UNSPEC)
+    {
+      ret1 = gethostbyname2_resolve (tc, hostname, AF_INET);
+      ret2 = gethostbyname2_resolve (tc, hostname, AF_INET6);
+      if ((ret1 == GNUNET_OK) || (ret2 == GNUNET_OK))
+        return GNUNET_OK;
+      if ((ret1 == GNUNET_SYSERR) || (ret2 == GNUNET_SYSERR))
+        return GNUNET_SYSERR;
+      return GNUNET_NO;
+    }
+  hp = gethostbyname2 (hostname, domain);
+  if (hp == NULL)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  _("Could not find IP of host `%s': %s\n"),
+                  hostname, hstrerror (h_errno));
+      return GNUNET_SYSERR;
+    }
+  GNUNET_assert (hp->h_addrtype == domain);
+  if (domain == AF_INET)
+    {
+      GNUNET_assert (hp->h_length == sizeof (struct in_addr));
+      memset (&a4, 0, sizeof (a4));
+      a4.sin_family = AF_INET;
+      memcpy (&a4.sin_addr, hp->h_addr_list[0], hp->h_length);
+      GNUNET_SERVER_transmit_context_append (tc,
+                                             &a4,
+                                             sizeof (a4),
+                                             GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
+    }
+  else
+    {
+      GNUNET_assert (hp->h_length == sizeof (struct in6_addr));
+      memset (&a6, 0, sizeof (a6));
+      a6.sin6_family = AF_INET6;
+      memcpy (&a6.sin6_addr, hp->h_addr_list[0], hp->h_length);
+      GNUNET_SERVER_transmit_context_append (tc,
+                                             &a6,
+                                             sizeof (a6),
+                                             GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
+    }
+  return GNUNET_OK;
+}
+#endif
+
+#if HAVE_GETHOSTBYNAME
+static int
+gethostbyname_resolve (struct GNUNET_SERVER_TransmitContext *tc,
+                       const char *hostname)
+{
+  struct hostent *hp;
+  struct sockaddr_in addr;
+
+  hp = GETHOSTBYNAME (hostname);
+  if (hp == NULL)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  _("Could not find IP of host `%s': %s\n"),
+                  hostname, hstrerror (h_errno));
+      return GNUNET_SYSERR;
+    }
+  if (hp->h_addrtype != AF_INET)
+    {
+      GNUNET_break (0);
+      return GNUNET_SYSERR;
+    }
+  GNUNET_assert (hp->h_length == sizeof (struct in_addr));
+  memset (&addr, 0, sizeof (addr));
+  addr.sin_family = AF_INET;
+  memcpy (&addr.sin_addr, hp->h_addr_list[0], hp->h_length);
+  GNUNET_SERVER_transmit_context_append (tc,
+                                         &addr,
+                                         sizeof (addr),
+                                         GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
+  return GNUNET_OK;
+}
+#endif
+
+
+/**
+ * Convert a string to an IP address.
+ *
+ * @param client where to send the IP address
+ * @param hostname the hostname to resolve
+ * @param domain AF_INET or AF_INET6; use AF_UNSPEC for "any"
+ */
+static void
+get_ip_from_hostname (struct GNUNET_SERVER_Client *client,
+                      const char *hostname, int domain)
+{
+  int ret;
+  struct GNUNET_SERVER_TransmitContext *tc;
+
+  tc = GNUNET_SERVER_transmit_context_create (client);
+  ret = GNUNET_NO;
+#if HAVE_GETADDRINFO
+  if (ret == GNUNET_NO)
+    ret = getaddrinfo_resolve (tc, hostname, domain);
+#endif
+#if HAVE_GETHOSTBYNAME2
+  if (ret == GNUNET_NO)
+    ret = gethostbyname2_resolve (tc, hostname, domain);
+#endif
+#if HAVE_GETHOSTBYNAME
+  if ((ret == GNUNET_NO) && ((domain == AF_UNSPEC) || (domain == PF_INET)))
+    gethostbyname_resolve (tc, hostname);
+#endif
+  GNUNET_SERVER_transmit_context_append (tc, NULL, 0,
+                                         GNUNET_MESSAGE_TYPE_RESOLVER_RESPONSE);
+  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
+}
+
+
+/**
+ * Handle GET-message.
+ *
+ * @param cls closure
+ * @param client identification of the client
+ * @param message the actual message
+ */
+static void
+handle_get (void *cls,
+            struct GNUNET_SERVER_Client *client,
+            const struct GNUNET_MessageHeader *message)
+{
+  uint16_t msize;
+  const struct GNUNET_RESOLVER_GetMessage *msg;
+  const char *hostname;
+  uint16_t size;
+  int direction;
+  int domain;
+
+  msize = ntohs (message->size);
+  if (msize < sizeof (struct GNUNET_RESOLVER_GetMessage))
+    {
+      GNUNET_break (0);
+      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
+      return;
+    }
+  msg = (const struct GNUNET_RESOLVER_GetMessage *) message;
+  size = msize - sizeof (struct GNUNET_RESOLVER_GetMessage);
+  direction = ntohl (msg->direction);
+  domain = ntohl (msg->domain);
+  if (direction == GNUNET_NO)
+    {
+      /* IP from hostname */
+      hostname = (const char *) &msg[1];
+      if (hostname[size - 1] != '\0')
+        {
+          GNUNET_break (0);
+          GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
+          return;
+        }
+#if DEBUG_RESOLVER
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  _("Resolver asked to look up `%s'.\n"), hostname);
+#endif
+      get_ip_from_hostname (client, hostname, domain);
+    }
+  else
+    {
+#if DEBUG_RESOLVER
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  _("Resolver asked to look up IP address.\n"));
+#endif
+      get_ip_as_string (client, (const struct sockaddr *) &msg[1], size);
+    }
+}
+
+
+/**
+ * List of handlers for the messages understood by this
+ * service.
+ */
+static struct GNUNET_SERVER_MessageHandler handlers[] = {
+  {&handle_get, NULL, GNUNET_MESSAGE_TYPE_RESOLVER_REQUEST, 0},
+  {NULL, NULL, 0, 0}
+};
+
+
+/**
+ * Process resolver requests.
+ *
+ * @param cls closure
+ * @param sched scheduler to use
+ * @param server the initialized server
+ * @param cfg configuration to use
+ */
+static void
+run (void *cls,
+     struct GNUNET_SCHEDULER_Handle *sched,
+     struct GNUNET_SERVER_Handle *server,
+     const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  GNUNET_SERVER_add_handlers (server, handlers);
+}
+
+
+/**
+ * The main function for the resolver service.
+ *
+ * @param argc number of arguments from the command line
+ * @param argv command line arguments
+ * @return 0 ok, 1 on error
+ */
+int
+main (int argc, char *const *argv)
+{
+  int ret;
+  struct IPCache *pos;
+
+  ret = (GNUNET_OK ==
+         GNUNET_SERVICE_run (argc,
+                             argv,
+                             "resolver", &run, NULL, NULL, NULL)) ? 0 : 1;
+
+  while (head != NULL)
+    {
+      pos = head->next;
+      GNUNET_free_non_null (head->addr);
+      GNUNET_free (head->sa);
+      GNUNET_free (head);
+      head = pos;
+    }
+  return ret;
+}
+
+/* end of gnunet-service-resolver.c */