moving plugin headers

6 files changed, 1097 insertions, 1 deletions

diff --git a/src/include/Makefile.am b/src/include/Makefile.am
index 70fd97bd0..a01c9268c 100644
--- a/src/include/Makefile.am
+++ b/src/include/Makefile.am
@@ -19,6 +19,7 @@ gnunetinclude_HEADERS = \
   gnunet_bandwidth_lib.h \
   gnunet_bio_lib.h \
   gnunet_block_lib.h \
+  gnunet_block_plugin.h \
   gnunet_client_lib.h \
   gnunet_common.h \
   gnunet_constants.h \
@@ -28,7 +29,9 @@ gnunetinclude_HEADERS = \
   gnunet_core_service.h \
   gnunet_crypto_lib.h \
   gnunet_datacache_lib.h \
+  gnunet_datacache_plugin.h \
   gnunet_datastore_service.h \
+  gnunet_datastore_plugin.h \
   gnunet_dht_service.h \
   gnunet_disk_lib.h \
   gnunet_dv_service.h \
@@ -57,5 +60,6 @@ gnunetinclude_HEADERS = \
   gnunet_testing_lib.h \
   gnunet_time_lib.h \
   gnunet_transport_service.h \
+  gnunet_transport_plugin.h \
   gnunet_upnp_service.h \
   gnunet_util_lib.h
diff --git a/src/include/gnunet_block_plugin.h b/src/include/gnunet_block_plugin.h
new file mode 100644
index 000000000..2a3e9e2ed
--- /dev/null
+++ b/src/include/gnunet_block_plugin.h
@@ -0,0 +1,118 @@
+/*
+     This file is part of GNUnet
+     (C) 2010 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 3, 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 block/gnunet_block_plugin.h
+ * @brief API for block plugins.  Each block plugin must conform to 
+ *        the API specified by this header.
+ * @author Christian Grothoff
+ */
+#ifndef PLUGIN_BLOCK_H
+#define PLUGIN_BLOCK_H
+
+#include "gnunet_util_lib.h"
+#include "gnunet_container_lib.h"
+#include "gnunet_block_lib.h"
+
+
+/**
+ * Function called to validate a reply or a request.  For
+ * request evaluation, simply pass "NULL" for the reply_block.
+ * Note that it is assumed that the reply has already been 
+ * matched to the key (and signatures checked) as it would
+ * be done with the "get_key" function.
+ *
+ * @param cls closure
+ * @param type block type
+ * @param query original query (hash)
+ * @param bf pointer to bloom filter associated with query; possibly updated (!)
+ * @param bf_mutator mutation value for bf
+ * @param xquery extrended query data (can be NULL, depending on type)
+ * @param xquery_size number of bytes in xquery
+ * @param reply_block response to validate
+ * @param reply_block_size number of bytes in reply block
+ * @return characterization of result
+ */
+typedef enum GNUNET_BLOCK_EvaluationResult
+  (*GNUNET_BLOCK_EvaluationFunction) (void *cls,
+                                      enum GNUNET_BLOCK_Type type,
+                                      const GNUNET_HashCode *query,
+                                      struct GNUNET_CONTAINER_BloomFilter **bf,
+                                      int32_t bf_mutator,
+                                      const void *xquery,
+                                      size_t xquery_size,
+                                      const void *reply_block,
+                                      size_t reply_block_size);
+
+
+/**
+ * Function called to obtain the key for a block.
+ *
+ * @param cls closure
+ * @param type block type
+ * @param block block to get the key for
+ * @param block_size number of bytes in block
+ * @param key set to the key (query) for the given block
+ * @return GNUNET_YES on success, 
+ *         GNUNET_NO if the block is malformed
+ *         GNUNET_SYSERR if type not supported
+ *         (or if extracting a key from a block of this type does not work)
+ */
+typedef int
+  (*GNUNET_BLOCK_GetKeyFunction) (void *cls,
+                                  enum GNUNET_BLOCK_Type type,
+                                  const void *block,
+                                  size_t block_size,
+                                  GNUNET_HashCode *key);
+                                  
+
+
+/**
+ * Each plugin is required to return a pointer to a struct of this
+ * type as the return value from its entry point.
+ */
+struct GNUNET_BLOCK_PluginFunctions
+{
+
+  /**
+   * Closure for all of the callbacks.
+   */
+  void *cls;
+
+  /**
+   * 0-terminated array of block types supported by this plugin.
+   */
+  const enum GNUNET_BLOCK_Type *types;
+
+  /**
+   * Main function of a block plugin.  Allows us to check if a 
+   * block matches a query.
+   */
+  GNUNET_BLOCK_EvaluationFunction evaluate;
+
+  /**
+   * Obtain the key for a given block (if possible).
+   */
+  GNUNET_BLOCK_GetKeyFunction get_key;
+
+};
+
+
+#endif
diff --git a/src/include/gnunet_datacache_plugin.h b/src/include/gnunet_datacache_plugin.h
new file mode 100644
index 000000000..6aa9b1d06
--- /dev/null
+++ b/src/include/gnunet_datacache_plugin.h
@@ -0,0 +1,158 @@
+/*
+     This file is part of GNUnet
+     (C) 2006, 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 datacache/gnunet_datacache_plugin.h
+ * @brief API for database backends for the datacache
+ * @author Christian Grothoff
+ */
+#ifndef PLUGIN_DATACACHE_H
+#define PLUGIN_DATACACHE_H
+
+#include "gnunet_datacache_lib.h"
+
+#ifdef __cplusplus
+extern "C"
+{
+#if 0                           /* keep Emacsens' auto-indent happy */
+}
+#endif
+#endif
+
+
+/**
+ * Function called by plugins to notify the datacache
+ * about content deletions.
+ * 
+ * @param cls closure
+ * @param key key of the content that was deleted
+ * @param size number of bytes that were made available
+ */
+typedef void (*GNUNET_DATACACHE_DeleteNotifyCallback)(void *cls,
+                                                      const GNUNET_HashCode *key,
+                                                      size_t size);
+
+
+/**
+ * The datastore service will pass a pointer to a struct
+ * of this type as the first and only argument to the
+ * entry point of each datastore plugin.
+ */
+struct GNUNET_DATACACHE_PluginEnvironment
+{
+  
+
+  /**
+   * Configuration to use.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Configuration section to use.
+   */
+  const char *section;
+
+  /**
+   * Closure to use for callbacks.
+   */
+  void *cls;
+
+  /**
+   * Function to call whenever the plugin needs to
+   * discard content that it was asked to store.
+   */
+  GNUNET_DATACACHE_DeleteNotifyCallback delete_notify;
+
+  /**
+   * How much space are we allowed to use?
+   */
+  unsigned long long quota;
+
+};
+
+
+/**
+ * @brief struct returned by the initialization function of the plugin
+ */
+struct GNUNET_DATACACHE_PluginFunctions {
+
+  /**
+   * Closure to pass to all plugin functions.
+   */ 
+  void *cls;
+
+  /**
+   * Store an item in the datastore.
+   *
+   * @param cls closure (internal context for the plugin)
+   * @param size number of bytes in data
+   * @param data data to store
+   * @param type type of the value
+   * @param discard_time when to discard the value in any case
+   * @return 0 on error, number of bytes used otherwise
+   */
+  size_t (*put) (void *cls,
+                 const GNUNET_HashCode * key,
+                 size_t size,
+                 const char *data,
+                 enum GNUNET_BLOCK_Type type,
+                 struct GNUNET_TIME_Absolute discard_time);
+
+
+  /**
+   * Iterate over the results for a particular key
+   * in the datastore.
+   *
+   * @param cls closure (internal context for the plugin)
+   * @param key
+   * @param type entries of which type are relevant?
+   * @param iter maybe NULL (to just count)
+   * @param iter_cls closure for iter
+   * @return the number of results found
+   */
+  unsigned int (*get) (void *cls,
+                       const GNUNET_HashCode * key,
+                       enum GNUNET_BLOCK_Type type,
+                       GNUNET_DATACACHE_Iterator iter,
+                       void *iter_cls);
+
+
+  /**
+   * Delete the entry with the lowest expiration value
+   * from the datacache right now.
+   * 
+   * @param cls closure (internal context for the plugin)
+   * @return GNUNET_OK on success, GNUNET_SYSERR on error
+   */ 
+  int (*del) (void *cls);
+
+
+};
+
+
+#if 0                           /* keep Emacsens' auto-indent happy */
+{
+#endif
+#ifdef __cplusplus
+}
+#endif
+
+/* end of gnunet_datacache_plugin.h */
+#endif
diff --git a/src/include/gnunet_datastore_plugin.h b/src/include/gnunet_datastore_plugin.h
new file mode 100644
index 000000000..832d53a68
--- /dev/null
+++ b/src/include/gnunet_datastore_plugin.h
@@ -0,0 +1,342 @@
+/*
+     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 datastore/gnunet_datastore_plugin.h
+ * @brief API for the database backend plugins.
+ * @author Christian Grothoff
+ */
+#ifndef PLUGIN_DATASTORE_H
+#define PLUGIN_DATASTORE_H
+
+#include "gnunet_block_lib.h"
+#include "gnunet_configuration_lib.h"
+#include "gnunet_datastore_service.h"
+#include "gnunet_statistics_service.h"
+#include "gnunet_scheduler_lib.h"
+
+
+/**
+ * How many bytes of overhead will we assume per entry
+ * in any DB (for reservations)?
+ */
+#define GNUNET_DATASTORE_ENTRY_OVERHEAD 256
+
+
+/**
+ * Function invoked to notify service of disk utilization
+ * changes.
+ *
+ * @param cls closure
+ * @param delta change in disk utilization, 
+ *        0 for "reset to empty"
+ */
+typedef void (*DiskUtilizationChange)(void *cls,
+                                      int delta);
+
+
+/**
+ * The datastore service will pass a pointer to a struct
+ * of this type as the first and only argument to the
+ * entry point of each datastore plugin.
+ */
+struct GNUNET_DATASTORE_PluginEnvironment
+{
+  /**
+   * Configuration to use.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Function to call on disk utilization change.
+   */
+  DiskUtilizationChange duc;
+
+  /**
+   * Closure.
+   */
+  void *cls;
+
+};
+
+
+/**
+ * Function invoked on behalf of a "PluginIterator"
+ * asking the database plugin to call the iterator
+ * with the next item.
+ *
+ * @param next_cls whatever argument was given
+ *        to the PluginIterator as "next_cls".
+ * @param end_it set to GNUNET_YES if we
+ *        should terminate the iteration early
+ *        (iterator should be still called once more
+ *         to signal the end of the iteration).
+ */
+typedef void (*PluginNextRequest)(void *next_cls,
+                                  int end_it);
+
+
+/**
+ * An iterator over a set of items stored in the datastore.
+ *
+ * @param cls closure
+ * @param next_cls closure to pass to the "next" function.
+ * @param key key for the content
+ * @param size number of bytes in data
+ * @param data content stored
+ * @param type type of the content
+ * @param priority priority of the content
+ * @param anonymity anonymity-level for the content
+ * @param expiration expiration time for the content
+ * @param uid unique identifier for the datum;
+ *        maybe 0 if no unique identifier is available
+ *
+ * @return GNUNET_SYSERR to abort the iteration, GNUNET_OK to continue
+ *         (continue on call to "next", of course),
+ *         GNUNET_NO to delete the item and continue (if supported)
+ */
+typedef int (*PluginIterator) (void *cls,
+                               void *next_cls,
+                               const GNUNET_HashCode * key,
+                               uint32_t size,
+                               const void *data,
+                               enum GNUNET_BLOCK_Type type,
+                               uint32_t priority,
+                               uint32_t anonymity,
+                               struct GNUNET_TIME_Absolute
+                               expiration, 
+                               uint64_t uid);
+
+/**
+ * Get an estimate of how much space the database is
+ * currently using.
+ *
+ * @param cls closure
+ * @return number of bytes used on disk
+ */
+typedef unsigned long long (*PluginGetSize) (void *cls);
+
+
+/**
+ * Store an item in the datastore.  If the item is already present,
+ * the priorities are summed up and the higher expiration time and
+ * lower anonymity level is used.
+ *
+ * @param cls closure
+ * @param key key for the item
+ * @param size number of bytes in data
+ * @param data content stored
+ * @param type type of the content
+ * @param priority priority of the content
+ * @param anonymity anonymity-level for the content
+ * @param expiration expiration time for the content
+ * @param msg set to an error message (on failure)
+ * @return GNUNET_OK on success, GNUNET_NO if the content
+ *         was already present (and may have been updated);
+ *         GNUNET_SYSERR on failure
+ */
+typedef int (*PluginPut) (void *cls,
+                          const GNUNET_HashCode * key,
+                          uint32_t size,
+                          const void *data,
+                          enum GNUNET_BLOCK_Type type,
+                          uint32_t priority,
+                          uint32_t anonymity,
+                          struct GNUNET_TIME_Absolute expiration,
+                           char **msg);
+
+
+/**
+ * Iterate over the results for a particular key
+ * in the datastore.
+ *
+ * @param cls closure
+ * @param key maybe NULL (to match all entries)
+ * @param vhash hash of the value, maybe NULL (to
+ *        match all values that have the right key).
+ *        Note that for DBlocks there is no difference
+ *        betwen key and vhash, but for other blocks
+ *        there may be!
+ * @param type entries of which type are relevant?
+ *     Use 0 for any type.
+ * @param iter function to call on each matching value; however,
+ *        after the first call to "iter", the plugin must wait
+ *        until "NextRequest" was called before giving the iterator
+ *        the next item; finally, the "iter" should be called once
+ *        once with a NULL value at the end ("next_cls" should be NULL
+ *        for that last call)
+ * @param iter_cls closure for iter
+ */
+typedef void (*PluginGet) (void *cls,
+                           const GNUNET_HashCode * key,
+                           const GNUNET_HashCode * vhash,
+                           enum GNUNET_BLOCK_Type type,
+                           PluginIterator iter, void *iter_cls);
+
+
+/**
+ * Update the priority for a particular key in the datastore.  If
+ * the expiration time in value is different than the time found in
+ * the datastore, the higher value should be kept.  For the
+ * anonymity level, the lower value is to be used.  The specified
+ * priority should be added to the existing priority, ignoring the
+ * priority in value.
+ *
+ * Note that it is possible for multiple values to match this put.
+ * In that case, all of the respective values are updated.
+ *
+ * @param cls closure
+ * @param uid unique identifier of the datum
+ * @param delta by how much should the priority
+ *     change?  If priority + delta < 0 the
+ *     priority should be set to 0 (never go
+ *     negative).
+ * @param expire new expiration time should be the
+ *     MAX of any existing expiration time and
+ *     this value
+ * @param msg set to an error message (on error)
+ * @return GNUNET_OK on success
+ */
+typedef int (*PluginUpdate) (void *cls,
+                             uint64_t uid,
+                             int delta, struct GNUNET_TIME_Absolute expire,
+                             char **msg);
+
+
+/**
+ * Select a subset of the items in the datastore and call
+ * the given iterator for each of them.
+ *
+ * @param cls closure
+ * @param type entries of which type should be considered?
+ *        Use 0 for any type.
+ * @param iter function to call on each matching value; however,
+ *        after the first call to "iter", the plugin must wait
+ *        until "NextRequest" was called before giving the iterator
+ *        the next item; finally, the "iter" should be called once
+ *        once with a NULL value at the end ("next_cls" should be NULL
+ *        for that last call)
+ * @param iter_cls closure for iter
+ */
+typedef void (*PluginSelector) (void *cls,
+                                enum GNUNET_BLOCK_Type type,
+                                PluginIterator iter,
+                                void *iter_cls);
+
+/**
+ * Drop database.
+ *
+ * @param cls closure
+ */
+typedef void (*PluginDrop) (void *cls);
+
+
+
+/**
+ * Each plugin is required to return a pointer to a struct of this
+ * type as the return value from its entry point.
+ */
+struct GNUNET_DATASTORE_PluginFunctions
+{
+
+  /**
+   * Closure to use for all of the following callbacks
+   * (except "next_request").
+   */
+  void *cls;
+
+  /**
+   * Get the current on-disk size of the SQ store.  Estimates are
+   * fine, if that's the only thing available.
+   */
+  PluginGetSize get_size;
+
+  /**
+   * Function to store an item in the datastore.
+   */
+  PluginPut put;
+
+  /**
+   * Function called by iterators whenever they want the next value;
+   * note that unlike all of the other callbacks, this one does get a
+   * the "next_cls" closure which is usually different from the "cls"
+   * member of this struct!
+   */
+  PluginNextRequest next_request;
+
+  /**
+   * Function to iterate over the results for a particular key
+   * in the datastore.
+   */
+  PluginGet get;
+
+  /**
+   * Update the priority for a particular key in the datastore.  If
+   * the expiration time in value is different than the time found in
+   * the datastore, the higher value should be kept.  For the
+   * anonymity level, the lower value is to be used.  The specified
+   * priority should be added to the existing priority, ignoring the
+   * priority in value.
+   */
+  PluginUpdate update;
+
+  /**
+   * Iterate over the items in the datastore in ascending
+   * order of priority.
+   */
+  PluginSelector iter_low_priority;
+
+  /**
+   * Iterate over content with anonymity zero.
+   */
+  PluginSelector iter_zero_anonymity;
+
+  /**
+   * Iterate over the items in the datastore in ascending order of
+   * expiration time. 
+   */
+  PluginSelector iter_ascending_expiration;
+
+  /**
+   * Iterate over the items in the datastore in migration
+   * order.  Call the given function on the next item only
+   * (and then signal 'end' with a second call).  This is
+   * a significant difference from all the other iterators!
+   */
+  PluginSelector iter_migration_order;
+
+  /**
+   * Iterate over all the items in the datastore
+   * as fast as possible in a single transaction
+   * (can lock datastore while this happens, focus
+   * is on doing it fast).
+   */
+  PluginSelector iter_all_now;
+
+  /**
+   * Delete the database.  The next operation is
+   * guaranteed to be unloading of the module.
+   */
+  PluginDrop drop;
+
+};
+
+
+#endif
diff --git a/src/include/gnunet_dv_service.h b/src/include/gnunet_dv_service.h
index 2bc77fefc..6915fb065 100644
--- a/src/include/gnunet_dv_service.h
+++ b/src/include/gnunet_dv_service.h
@@ -40,7 +40,7 @@ extern "C"
 #include "gnunet_common.h"
 #include "gnunet_configuration_lib.h"
 #include "gnunet_scheduler_lib.h"
-#include "../transport/plugin_transport.h"
+#include "../transport/gnunet_transport_plugin.h"
 
 /**
  * Version of the dv API.
diff --git a/src/include/gnunet_transport_plugin.h b/src/include/gnunet_transport_plugin.h
new file mode 100644
index 000000000..38c79f07f
--- /dev/null
+++ b/src/include/gnunet_transport_plugin.h
@@ -0,0 +1,474 @@
+/*
+     This file is part of GNUnet
+     (C) 2009, 2010 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 3, 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 transport/gnunet_transport_plugin.h
+ * @brief API for the transport services.  This header
+ *        specifies the struct that is given to the plugin's entry
+ *        method and the other struct that must be returned.
+ *        Note that the destructors of transport plugins will
+ *        be given the value returned by the constructor
+ *        and is expected to return a NULL pointer.
+ * @author Christian Grothoff
+ */
+#ifndef PLUGIN_TRANSPORT_H
+#define PLUGIN_TRANSPORT_H
+
+#include "gnunet_configuration_lib.h"
+#include "gnunet_scheduler_lib.h"
+#include "gnunet_statistics_service.h"
+#include "gnunet_transport_service.h"
+#include "transport_selection.h"
+
+
+/**
+ * Opaque pointer that plugins can use to distinguish specific
+ * connections to a given peer.  Typically used by stateful plugins to
+ * allow the service to refer to specific streams instead of a more
+ * general notion of "some connection" to the given peer.  This is
+ * useful since sometimes (i.e. for inbound TCP connections) a
+ * connection may not have an address that can be used for meaningful
+ * distinction between sessions to the same peer.
+ */
+struct Session;
+
+/**
+ * Every 'struct Session' must begin with this header.
+ */
+struct SessionHeader
+{
+
+  /**
+   * Cached signature for PONG generation for the session.  Do not use
+   * in the plugin!
+   */
+  struct GNUNET_CRYPTO_RsaSignature pong_signature;
+
+  /**
+   * Expiration time for signature.  Do not use in the plugin!
+   */
+  struct GNUNET_TIME_Absolute pong_sig_expires;
+  
+};
+
+/**
+ * Function that will be called whenever the plugin internally
+ * cleans up a session pointer and hence the service needs to
+ * discard all of those sessions as well.  Plugins that do not
+ * use sessions can simply omit calling this function and always
+ * use NULL wherever a session pointer is needed.
+ * 
+ * @param cls closure
+ * @param peer which peer was the session for 
+ * @param session which session is being destoyed
+ */
+typedef void (*GNUNET_TRANSPORT_SessionEnd) (void *cls,
+                                             const struct GNUNET_PeerIdentity *peer,
+                                             struct Session *session);
+
+
+/**
+ * Function called by the transport for each received message.
+ * This function should also be called with "NULL" for the
+ * message to signal that the other peer disconnected.
+ *
+ * @param cls closure
+ * @param peer (claimed) identity of the other peer
+ * @param message the message, NULL if we only care about
+ *                learning about the delay until we should receive again -- FIXME!
+ * @param distance in overlay hops; use 1 unless DV (or 0 if message == NULL)
+ * @param session identifier used for this session (NULL for plugins
+ *                that do not offer bi-directional communication to the sender
+ *                using the same "connection")
+ * @param sender_address binary address of the sender (if we established the
+ *                connection or are otherwise sure of it; should be NULL
+ *                for inbound TCP/UDP connections since it it not clear
+ *                that we could establish ourselves a connection to that
+ *                IP address and get the same system)
+ * @param sender_address_len number of bytes in sender_address
+ * @return how long the plugin should wait until receiving more data
+ *         (plugins that do not support this, can ignore the return value)
+ */
+typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_PluginReceiveCallback) (void *cls,
+                                                                               const struct
+                                                                               GNUNET_PeerIdentity *
+                                                                               peer,
+                                                                               const struct
+                                                                               GNUNET_MessageHeader *
+                                                                               message,
+                                                                               uint32_t distance,
+                                                                               struct Session *session,
+                                                                               const char *sender_address,
+                                                                               uint16_t sender_address_len);
+
+
+/**
+ * Function that will be called for each address the transport
+ * is aware that it might be reachable under.
+ *
+ * @param cls closure
+ * @param name name of the transport that generated the address
+ * @param addr one of the addresses of the host, NULL for the last address
+ *        the specific address format depends on the transport
+ * @param addrlen length of the address
+ * @param expires when should this address automatically expire?
+ */
+typedef void (*GNUNET_TRANSPORT_AddressNotification) (void *cls,
+                                                      const char *name,
+                                                      const void *addr,
+                                                      uint16_t addrlen,
+                                                      struct
+                                                      GNUNET_TIME_Relative
+                                                      expires);
+
+/**
+ * Function that will be called whenever the plugin receives data over
+ * the network and wants to determine how long it should wait until
+ * the next time it reads from the given peer.  Note that some plugins
+ * (such as UDP) may not be able to wait (for a particular peer), so
+ * the waiting part is optional.  Plugins that can wait should call
+ * this function, sleep the given amount of time, and call it again
+ * (with zero bytes read) UNTIL it returns zero and only then read.
+ *
+ * @param cls closure
+ * @param peer which peer did we read data from
+ * @param amount_recved number of bytes read (can be zero)
+ * @return how long to wait until reading more from this peer
+ *         (to enforce inbound quotas)
+ */
+typedef struct GNUNET_TIME_Relative (*GNUNET_TRANSPORT_TrafficReport) (void *cls,
+                                                                      const struct
+                                                                      GNUNET_PeerIdentity *peer,
+                                                                      size_t amount_recved);
+
+/**
+ * Function called whenever the plugin has to notify ATS about costs for using this transport
+ *
+ * The cost will be passed as struct GNUNET_ATS_Cost_Information[]
+ * This array is 0-terminated, so the last element will be a pair:
+ * ((cost->cost_type==GNUNET_ATS_ARRAY_TERMINATOR) && cost->cost_value==0))
+ *
+ * @param cls closure
+ * @param peer peer
+ * @param addr peer address
+ * @param addrlen address length
+ * @param cost pointer to the first element of struct GNUNET_ATS_Cost_Information[]
+ */
+typedef void (*GNUNET_TRANSPORT_CostReport) (void *cls,
+                                                                                         const struct GNUNET_PeerIdentity *peer,
+                                             const void *addr,
+                                             uint16_t addrlen,
+                                                                                         struct GNUNET_ATS_Information * cost);
+
+/**
+ * The transport service will pass a pointer to a struct
+ * of this type as the first and only argument to the
+ * entry point of each transport plugin.
+ */
+struct GNUNET_TRANSPORT_PluginEnvironment
+{
+  /**
+   * Configuration to use.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Identity of this peer.
+   */
+  const struct GNUNET_PeerIdentity *my_identity;
+
+  /**
+   * Pointer (!) to our HELLO message.  Note that the address
+   * referred to "*our_hello" might change over time.
+   */
+  struct GNUNET_HELLO_Message *const*our_hello;
+
+  /**
+   * Closure for the various callbacks.
+   */
+  void *cls;
+
+  /**
+   * Handle for reporting statistics.
+   */
+  struct GNUNET_STATISTICS_Handle *stats;
+
+  /**
+   * Function that should be called by the transport plugin
+   * whenever a message is received.
+   */
+  GNUNET_TRANSPORT_PluginReceiveCallback receive;
+
+  /**
+   * Function that must be called by each plugin to notify the
+   * transport service about the addresses under which the transport
+   * provided by the plugin can be reached.
+   */
+  GNUNET_TRANSPORT_AddressNotification notify_address;
+
+  /**
+   * Inform service about traffic received, get information
+   * about when we might be willing to receive more.
+   */
+  GNUNET_TRANSPORT_TrafficReport traffic_report;
+
+  /**
+   * Function that must be called by the plugin when a non-NULL
+   * session handle stops being valid (is destroyed).
+   */
+  GNUNET_TRANSPORT_SessionEnd session_end;
+
+  /**
+   * Inform service about costs for using this transport plugin
+   */
+  GNUNET_TRANSPORT_CostReport cost_report;
+
+  /**
+   * What is the maximum number of connections that this transport
+   * should allow?  Transports that do not have sessions (such as
+   * UDP) can ignore this value.
+   */
+  uint32_t max_connections;
+
+};
+
+
+/**
+ * Function called by the GNUNET_TRANSPORT_TransmitFunction
+ * upon "completion".
+ *
+ * @param cls closure
+ * @param target who was the recipient of the message?
+ * @param result GNUNET_OK on success
+ *               GNUNET_SYSERR if the target disconnected;
+ *               disconnect will ALSO be signalled using
+ *               the ReceiveCallback.
+ */
+typedef void
+  (*GNUNET_TRANSPORT_TransmitContinuation) (void *cls,
+                                            const struct GNUNET_PeerIdentity *
+                                            target, int result);
+
+
+/**
+ * Function that can be used by the transport service to transmit
+ * a message using the plugin.   Note that in the case of a
+ * peer disconnecting, the continuation MUST be called
+ * prior to the disconnect notification itself.  This function
+ * will be called with this peer's HELLO message to initiate
+ * a fresh connection to another peer.
+ *
+ * @param cls closure
+ * @param target who should receive this message
+ * @param msgbuf the message to transmit
+ * @param msgbuf_size number of bytes in 'msgbuf'
+ * @param priority how important is the message (most plugins will
+ *                 ignore message priority and just FIFO)
+ * @param timeout how long to wait at most for the transmission (does not
+ *                require plugins to discard the message after the timeout,
+ *                just advisory for the desired delay; most plugins will ignore
+ *                this as well)
+ * @param session which session must be used (or NULL for "any")
+ * @param addr the address to use (can be NULL if the plugin
+ *                is "on its own" (i.e. re-use existing TCP connection))
+ * @param addrlen length of the address in bytes
+ * @param force_address GNUNET_YES if the plugin MUST use the given address,
+ *                GNUNET_NO means the plugin may use any other address and
+ *                GNUNET_SYSERR means that only reliable existing
+ *                bi-directional connections should be used (regardless
+ *                of address)
+ * @param cont continuation to call once the message has
+ *        been transmitted (or if the transport is ready
+ *        for the next transmission call; or if the
+ *        peer disconnected...); can be NULL
+ * @param cont_cls closure for cont
+ * @return number of bytes used (on the physical network, with overheads);
+ *         -1 on hard errors (i.e. address invalid); 0 is a legal value
+ *         and does NOT mean that the message was not transmitted (DV)
+ */
+typedef ssize_t
+  (*GNUNET_TRANSPORT_TransmitFunction) (void *cls,
+                                        const struct GNUNET_PeerIdentity *
+                                        target,
+                                        const char *msgbuf,
+                                        size_t msgbuf_size,
+                                        uint32_t priority,
+                                        struct GNUNET_TIME_Relative timeout,
+                                        struct Session *session,
+                                        const void *addr,
+                                        size_t addrlen,
+                                        int force_address,
+                                        GNUNET_TRANSPORT_TransmitContinuation
+                                        cont, void *cont_cls);
+
+
+/**
+ * Function that can be called to force a disconnect from the
+ * specified neighbour.  This should also cancel all previously
+ * scheduled transmissions.  Obviously the transmission may have been
+ * partially completed already, which is OK.  The plugin is supposed
+ * to close the connection (if applicable) and no longer call the
+ * transmit continuation(s).
+ *
+ * Finally, plugin MUST NOT call the services's receive function to
+ * notify the service that the connection to the specified target was
+ * closed after a getting this call.
+ *
+ * @param cls closure
+ * @param target peer for which the last transmission is
+ *        to be cancelled
+ */
+typedef void
+  (*GNUNET_TRANSPORT_DisconnectFunction) (void *cls,
+                                          const struct GNUNET_PeerIdentity *
+                                          target);
+
+
+/**
+ * Function called by the pretty printer for the resolved address for
+ * each human-readable address obtained.
+ *
+ * @param cls closure
+ * @param hostname one of the names for the host, NULL
+ *        on the last call to the callback
+ */
+typedef void (*GNUNET_TRANSPORT_AddressStringCallback) (void *cls,
+                                                        const char *address);
+
+
+/**
+ * Convert the transports address to a nice, human-readable
+ * format.
+ *
+ * @param cls closure
+ * @param name name of the transport that generated the address
+ * @param addr one of the addresses of the host, NULL for the last address
+ *        the specific address format depends on the transport
+ * @param addrlen length of the address
+ * @param numeric should (IP) addresses be displayed in numeric form?
+ * @param timeout after how long should we give up?
+ * @param asc function to call on each string
+ * @param asc_cls closure for asc
+ */
+typedef void
+  (*GNUNET_TRANSPORT_AddressPrettyPrinter) (void *cls,
+                                            const char *type,
+                                            const void *addr,
+                                            size_t addrlen,
+                                            int numeric,
+                                            struct GNUNET_TIME_Relative
+                                            timeout,
+                                            GNUNET_TRANSPORT_AddressStringCallback
+                                            asc, void *asc_cls);
+
+
+/**
+ * Another peer has suggested an address for this peer and transport
+ * plugin.  Check that this could be a valid address.  This function
+ * is not expected to 'validate' the address in the sense of trying to
+ * connect to it but simply to see if the binary format is technically
+ * legal for establishing a connection to this peer (and make sure that
+ * the address really corresponds to our network connection/settings
+ * and not some potential man-in-the-middle).
+ *
+ * @param addr pointer to the address
+ * @param addrlen length of addr
+ * @return GNUNET_OK if this is a plausible address for this peer
+ *         and transport, GNUNET_SYSERR if not
+ */
+typedef int
+(*GNUNET_TRANSPORT_CheckAddress) (void *cls,
+                                  const void *addr, size_t addrlen);
+
+
+/**
+ * Function called for a quick conversion of the binary address to
+ * a numeric address.  Note that the caller must not free the 
+ * address and that the next call to this function is allowed
+ * to override the address again.
+ *
+ * @param cls closure
+ * @param addr binary address
+ * @param addr_len length of the address
+ * @return string representing the same address 
+ */
+typedef const char* (*GNUNET_TRANSPORT_AddressToString) (void *cls,
+                                                         const void *addr,
+                                                         size_t addrlen);
+
+
+/**
+ * Each plugin is required to return a pointer to a struct of this
+ * type as the return value from its entry point.
+ */
+struct GNUNET_TRANSPORT_PluginFunctions
+{
+
+  /**
+   * Closure for all of the callbacks.
+   */
+  void *cls;
+
+  /**
+   * Function that the transport service will use to transmit data to
+   * another peer.  May be NULL for plugins that only support
+   * receiving data.  After this call, the plugin call the specified
+   * continuation with success or error before notifying us about the
+   * target having disconnected.
+   */
+  GNUNET_TRANSPORT_TransmitFunction send;
+
+  /**
+   * Function that can be used to force the plugin to disconnect from
+   * the given peer and cancel all previous transmissions (and their
+   * continuations).  Note that if the transport does not have
+   * sessions / persistent connections (for example, UDP), this
+   * function may very well do nothing.
+   */
+  GNUNET_TRANSPORT_DisconnectFunction disconnect;
+
+  /**
+   * Function to pretty-print addresses.  NOTE: this function is not
+   * yet used by transport-service, but will be used in the future
+   * once the transport-API has been completed.
+   */
+  GNUNET_TRANSPORT_AddressPrettyPrinter address_pretty_printer;
+
+  /**
+   * Function that will be called to check if a binary address
+   * for this plugin is well-formed and corresponds to an
+   * address for THIS peer (as per our configuration).  Naturally,
+   * if absolutely necessary, plugins can be a bit conservative in
+   * their answer, but in general plugins should make sure that the
+   * address does not redirect traffic to a 3rd party that might
+   * try to man-in-the-middle our traffic.
+   */
+  GNUNET_TRANSPORT_CheckAddress check_address;
+
+  /**
+   * Function that will be called to convert a binary address
+   * to a string (numeric conversion only).
+   */
+  GNUNET_TRANSPORT_AddressToString address_to_string;
+
+};
+
+
+#endif