Fax gateway functionality (i.e. translating between a T.30 terminal and a T.38
authorMatthew Nicholson <mnicholson@digium.com>
Thu, 30 Jun 2011 18:22:28 +0000 (18:22 +0000)
committerMatthew Nicholson <mnicholson@digium.com>
Thu, 30 Jun 2011 18:22:28 +0000 (18:22 +0000)
terminal). Can be enabled on a channel by setting FAXOPT(gateway)=yes in the
dialplan.

Big thanks to irroot for porting this code to use the framehooks api.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@325816 65c4cc65-6c06-0410-ace0-fbb531ad65f3

CHANGES
include/asterisk/res_fax.h
res/res_fax.c
res/res_fax_spandsp.c

diff --git a/CHANGES b/CHANGES
index 2dcc9b5..53d4957 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -150,6 +150,16 @@ pbx_lua
    stopped and restarted using the autoservice_stop() and autoservice_start()
    functions.
 
+res_fax
+--------------------------
+ * The ReceiveFAXStatus and SendFAXStatus manager events have been consolidated
+   into a FAXStatus event with an 'Operation' header that will be either
+   'send', 'receive', and 'gateway'.
+ * T.38 gateway functionality has been added to res_fax (and res_fax_spandsp).
+   Set FAXOPT(gateway)=yes to enable this functionality on a channel. This
+   feature will handle converting a fax call between an audio T.30 fax terminal
+   and an IFP T.38 fax terminal.
+
 ------------------------------------------------------------------------------
 --- Functionality changes from Asterisk 1.6.2 to Asterisk 1.8 ----------------
 ------------------------------------------------------------------------------
index 9a52115..5d2c903 100644 (file)
@@ -42,6 +42,8 @@ enum ast_fax_capabilities {
        AST_FAX_TECH_T38       = (1 << 3),
        /*! sending mulitple documents supported */
        AST_FAX_TECH_MULTI_DOC = (1 << 4),
+       /*! T.38 - T.30 Gateway */
+       AST_FAX_TECH_GATEWAY = (1 << 5),
 };
 
 /*! \brief fax modem capabilities */
@@ -168,6 +170,8 @@ struct ast_fax_session_details {
        struct ast_fax_t38_parameters our_t38_parameters;
        /*! the other endpoint's T.38 session parameters, if any */
        struct ast_fax_t38_parameters their_t38_parameters;
+       /*! the id of the t.38 gateway framehook for this channel */
+       int gateway_id;
 };
 
 struct ast_fax_tech;
@@ -204,6 +208,9 @@ struct ast_fax_session {
        struct ast_smoother *smoother;
 };
 
+/* if this overlaps with any AST_FRFLAG_* values, problems will occur */
+#define AST_FAX_FRFLAG_GATEWAY (1 << 13)
+
 /*! \brief used to register a FAX technology module with res_fax */
 struct ast_fax_tech {
        /*! the type of fax session supported with this ast_fax_tech structure */
index e323fba..63c5367 100644 (file)
@@ -5,6 +5,23 @@
  *
  * Dwayne M. Hubbard <dhubbard@digium.com>
  * Kevin P. Fleming <kpfleming@digium.com>
+ * Matthew Nicholson <mnicholson@digium.com>
+ *
+ * Initial T.38-gateway code
+ * 2008, Daniel Ferenci <daniel.ferenci@nethemba.com>
+ * Created by Nethemba s.r.o. http://www.nethemba.com
+ * Sponsored by IPEX a.s. http://www.ipex.cz
+ *
+ * T.38-gateway integration into asterisk app_fax and rework
+ * 2008, Gregory Hinton Nietsky <gregory@dnstelecom.co.za>
+ * dns Telecom http://www.dnstelecom.co.za
+ *
+ * Modified to make T.38-gateway compatible with Asterisk 1.6.2
+ * 2010, Anton Verevkin <mymail@verevkin.it>
+ * ViaNetTV http://www.vianettv.com
+ *
+ * Modified to make T.38-gateway work
+ * 2010, Klaus Darilion, IPCom GmbH, www.ipcom.at
  *
  * See http://www.asterisk.org for more information about
  * the Asterisk project. Please do not directly contact
@@ -27,6 +44,7 @@
  *
  * \author Dwayne M. Hubbard <dhubbard@digium.com>
  * \author Kevin P. Fleming <kpfleming@digium.com>
+ * \author Matthew Nicholson <mnicholson@digium.com>
  * 
  * A generic FAX resource module that provides SendFAX and ReceiveFAX applications.
  * This module requires FAX technology modules, like res_fax_spandsp, to register with it
@@ -58,6 +76,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/dsp.h"
 #include "asterisk/indications.h"
 #include "asterisk/ast_version.h"
+#include "asterisk/translate.h"
 
 /*** DOCUMENTATION
        <application name="ReceiveFax" language="en_US">
@@ -165,6 +184,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
                                        <enum name="modem">
                                                <para>R/W Modem type (v17/v27/v29).</para>
                                        </enum>
+                                       <enum name="gateway">
+                                               <para>R/W T38 Gateway Enabled (yes/no)</para>
+                                       </enum>
                                        <enum name="pages">
                                                <para>R/O Number of pages transferred.</para>
                                        </enum>
@@ -215,12 +237,37 @@ struct ast_fax_debug_info {
        struct ast_dsp *dsp;
 };
 
+/*! \brief used for gateway framehook */
+struct fax_gateway {
+       /*! \brief FAX Session */
+       struct ast_fax_session *s;
+       /*! \brief reserved fax session token */
+       struct ast_fax_tech_token *token;
+       /*! \brief the start of our timeout counter */
+       struct timeval timeout_start;
+       /*! \brief DSP Processor */
+       struct ast_dsp *chan_dsp;
+       struct ast_dsp *peer_dsp;
+       /*! \brief framehook used in gateway mode */
+       int framehook;
+       /*! \brief bridged */
+       int bridged:1;
+       /*! \brief a flag to track the state of our negotiation */
+       enum ast_t38_state t38_state;
+       /*! \brief original audio formats */
+       struct ast_format chan_read_format;
+       struct ast_format chan_write_format;
+       struct ast_format peer_read_format;
+       struct ast_format peer_write_format;
+};
+
 static int fax_logger_level = -1;
 
 /*! \brief maximum buckets for res_fax ao2 containers */
 #define FAX_MAXBUCKETS 10
 
 #define RES_FAX_TIMEOUT 10000
+#define FAX_GATEWAY_TIMEOUT RES_FAX_TIMEOUT
 
 /*! \brief The faxregistry is used to manage information and statistics for all FAX sessions. */
 static struct {
@@ -397,10 +444,40 @@ static struct ast_fax_session_details *session_details_new(void)
        d->modems = general_options.modems;
        d->minrate = general_options.minrate;
        d->maxrate = general_options.maxrate;
+       d->gateway_id = -1;
 
        return d;
 }
 
+static struct ast_control_t38_parameters our_t38_parameters = {
+       .version = 0,
+       .max_ifp = 400,
+       .rate = AST_T38_RATE_14400,
+       .rate_management = AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF,
+};
+
+static void t38_parameters_ast_to_fax(struct ast_fax_t38_parameters *dst, const struct ast_control_t38_parameters *src)
+{
+       dst->version = src->version;
+       dst->max_ifp = src->max_ifp;
+       dst->rate = src->rate;
+       dst->rate_management = src->rate_management;
+       dst->fill_bit_removal = src->fill_bit_removal;
+       dst->transcoding_mmr = src->transcoding_mmr;
+       dst->transcoding_jbig = src->transcoding_jbig;
+}
+
+static void t38_parameters_fax_to_ast(struct ast_control_t38_parameters *dst, const struct ast_fax_t38_parameters *src)
+{
+       dst->version = src->version;
+       dst->max_ifp = src->max_ifp;
+       dst->rate = src->rate;
+       dst->rate_management = src->rate_management;
+       dst->fill_bit_removal = src->fill_bit_removal;
+       dst->transcoding_mmr = src->transcoding_mmr;
+       dst->transcoding_jbig = src->transcoding_jbig;
+}
+
 /*! \brief returns a reference counted details structure from the channel's fax datastore.  If the datastore
  * does not exist it will be created */        
 static struct ast_fax_session_details *find_or_create_details(struct ast_channel *chan)
@@ -423,6 +500,11 @@ static struct ast_fax_session_details *find_or_create_details(struct ast_channel
        }
        /* add the datastore to the channel and increment the refcount */
        datastore->data = details;
+
+       /* initialize default T.38 parameters */
+       t38_parameters_ast_to_fax(&details->our_t38_parameters, &our_t38_parameters);
+       t38_parameters_ast_to_fax(&details->their_t38_parameters, &our_t38_parameters);
+
        ao2_ref(details, 1);
        ast_channel_lock(chan);
        ast_channel_datastore_add(chan, datastore);
@@ -645,6 +727,19 @@ static unsigned int fax_rate_str_to_int(const char *ratestr)
        }
 }
 
+/*! \brief Release a session token.
+ * \param s a session returned from fax_session_reserve()
+ * \param token a token generated from fax_session_reserve()
+ *
+ * This function releases the given token and marks the given session as no
+ * longer reserved. It is safe to call on a session that is not actually
+ * reserved and with a NULL token. This is so that sessions returned by
+ * technologies that do not support reserved sessions don't require extra logic
+ * to handle.
+ *
+ * \note This function DOES NOT release the given fax session, only the given
+ * token.
+ */
 static void fax_session_release(struct ast_fax_session *s, struct ast_fax_tech_token *token)
 {
        if (token) {
@@ -691,6 +786,19 @@ static void destroy_session(void *session)
        ast_free(s->chan_uniqueid);
 }
 
+/*! \brief Reserve a fax session.
+ * \param details the fax session details
+ * \param token a pointer to a place to store a token to be passed to fax_session_new() later
+ *
+ * This function reserves a fax session for use later. If the selected fax
+ * technology does not support reserving sessions a session will still be
+ * returned but token will not be set.
+ *
+ * \note The reference returned by this function does not get consumed by
+ * fax_session_new() and must always be dereferenced separately.
+ *
+ * \return NULL or an uninitialized and possibly reserved session
+ */
 static struct ast_fax_session *fax_session_reserve(struct ast_fax_session_details *details, struct ast_fax_tech_token **token)
 {
        struct ast_fax_session *s;
@@ -701,6 +809,8 @@ static struct ast_fax_session *fax_session_reserve(struct ast_fax_session_detail
        }
 
        s->state = AST_FAX_STATE_INACTIVE;
+       s->details = details;
+       ao2_ref(s->details, 1);
 
        /* locate a FAX technology module that can handle said requirements
         * Note: the requirements have not yet been finalized as T.38
@@ -739,7 +849,22 @@ static struct ast_fax_session *fax_session_reserve(struct ast_fax_session_detail
        return s;
 }
 
-/*! \brief create a FAX session */
+/*! \brief create a FAX session
+ *
+ * \param details details for the session
+ * \param chan the channel the session will run on
+ * \param reserved a reserved session to base this session on (can be NULL)
+ * \param token the token for a reserved session (can be NULL)
+ *
+ * Create a new fax session based on the given details structure.
+ *
+ * \note The given token is always consumed (by tech->new_session() or by
+ * fax_session_release() in the event of a failure). The given reference to a
+ * reserved session is never consumed and must be dereferenced separately from
+ * the reference returned by this function.
+ *
+ * \return NULL or a reference to a new fax session
+ */
 static struct ast_fax_session *fax_session_new(struct ast_fax_session_details *details, struct ast_channel *chan, struct ast_fax_session *reserved, struct ast_fax_tech_token *token)
 {
        struct ast_fax_session *s = NULL;
@@ -749,6 +874,12 @@ static struct ast_fax_session *fax_session_new(struct ast_fax_session_details *d
                s = reserved;
                ao2_ref(reserved, +1);
 
+               /* NOTE: we don't consume the reference to the reserved
+                * session. The session returned from fax_session_new() is a
+                * new reference and must be derefed in addition to the
+                * reserved session.
+                */
+
                if (s->state == AST_FAX_STATE_RESERVED) {
                        ast_atomic_fetchadd_int(&faxregistry.reserved_sessions, -1);
                        s->state = AST_FAX_STATE_UNINITIALIZED;
@@ -791,8 +922,10 @@ static struct ast_fax_session *fax_session_new(struct ast_fax_session_details *d
        }
 
        s->chan = chan;
-       s->details = details;
-       ao2_ref(s->details, 1);
+       if (!s->details) {
+               s->details = details;
+               ao2_ref(s->details, 1);
+       }
 
        details->id = s->id = ast_atomic_fetchadd_int(&faxregistry.nextsessionname, 1);
 
@@ -892,9 +1025,6 @@ static char *generate_filenames_string(struct ast_fax_session_details *details,
 static int report_fax_status(struct ast_channel *chan, struct ast_fax_session_details *details, const char *status)
 {
        char *filenames = generate_filenames_string(details, "FileName: ", "\r\n");
-       if (!filenames) {
-               return 1;
-       }
 
        ast_channel_lock(chan);
        if (details->option.statusevents) {
@@ -902,24 +1032,30 @@ static int report_fax_status(struct ast_channel *chan, struct ast_fax_session_de
 
                get_manager_event_info(chan, &info);
                manager_event(EVENT_FLAG_CALL,
-                             (details->caps & AST_FAX_TECH_RECEIVE) ? "ReceiveFAXStatus" : "SendFAXStatus",
+                             "FAXStatus",
+                             "Operation: %s\r\n"
                              "Status: %s\r\n"
                              "Channel: %s\r\n"
                              "Context: %s\r\n"
                              "Exten: %s\r\n"
                              "CallerID: %s\r\n"
                              "LocalStationID: %s\r\n"
-                             "%s\r\n",
+                             "%s%s",
+                             (details->caps & AST_FAX_TECH_GATEWAY) ? "gateway" : (details->caps & AST_FAX_TECH_RECEIVE) ? "receive" : "send",
                              status,
                              chan->name,
                              info.context,
                              info.exten,
                              info.cid,
                              details->localstationid,
-                             filenames);
+                             S_OR(filenames, ""),
+                             filenames ? "\r\n" : "");
        }
        ast_channel_unlock(chan);
-       ast_free(filenames);
+
+       if (filenames) {
+               ast_free(filenames);
+       }
 
        return 0;
 }
@@ -963,28 +1099,6 @@ static void set_channel_variables(struct ast_channel *chan, struct ast_fax_sessi
                GENERIC_FAX_EXEC_ERROR_QUIET(fax, chan, errorstr, reason); \
        } while (0)
 
-static void t38_parameters_ast_to_fax(struct ast_fax_t38_parameters *dst, const struct ast_control_t38_parameters *src)
-{
-       dst->version = src->version;
-       dst->max_ifp = src->max_ifp;
-       dst->rate = src->rate;
-       dst->rate_management = src->rate_management;
-       dst->fill_bit_removal = src->fill_bit_removal;
-       dst->transcoding_mmr = src->transcoding_mmr;
-       dst->transcoding_jbig = src->transcoding_jbig;
-}
-
-static void t38_parameters_fax_to_ast(struct ast_control_t38_parameters *dst, const struct ast_fax_t38_parameters *src)
-{
-       dst->version = src->version;
-       dst->max_ifp = src->max_ifp;
-       dst->rate = src->rate;
-       dst->rate_management = src->rate_management;
-       dst->fill_bit_removal = src->fill_bit_removal;
-       dst->transcoding_mmr = src->transcoding_mmr;
-       dst->transcoding_jbig = src->transcoding_jbig;
-}
-
 static int set_fax_t38_caps(struct ast_channel *chan, struct ast_fax_session_details *details)
 {
        switch (ast_channel_get_t38_state(chan)) {
@@ -995,6 +1109,8 @@ static int set_fax_t38_caps(struct ast_channel *chan, struct ast_fax_session_det
        case T38_STATE_UNAVAILABLE:
                details->caps |= AST_FAX_TECH_AUDIO;
                break;
+       case T38_STATE_NEGOTIATED:
+               /* already in T.38 mode? This should not happen. */
        case T38_STATE_NEGOTIATING: {
                /* the other end already sent us a T.38 reinvite, so we need to prod the channel
                 * driver into resending their parameters to us if it supports doing so... if
@@ -1076,13 +1192,6 @@ static int disable_t38(struct ast_channel *chan)
        return 0;
 }
 
-static struct ast_control_t38_parameters our_t38_parameters = {
-       .version = 0,
-       .max_ifp = 400,
-       .rate = AST_T38_RATE_14400,
-       .rate_management = AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF,
-};
-
 /*! \brief this is the generic FAX session handling function */
 static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_details *details, struct ast_fax_session *reserved, struct ast_fax_tech_token *token)
 {
@@ -1350,8 +1459,6 @@ static int receivefax_t38_init(struct ast_channel *chan, struct ast_fax_session_
        struct ast_frame *frame = NULL;
        struct ast_control_t38_parameters t38_parameters;
 
-       t38_parameters_ast_to_fax(&details->our_t38_parameters, &our_t38_parameters);
-
        /* don't send any audio if we've already received a T.38 reinvite */
        if (ast_channel_get_t38_state(chan) != T38_STATE_NEGOTIATING) {
                /* generate 3 seconds of CED */
@@ -1535,6 +1642,14 @@ static int receivefax_exec(struct ast_channel *chan, const char *data)
        ast_string_field_set(details, error, "INIT_ERROR");
        set_channel_variables(chan, details);
 
+       if (details->caps & AST_FAX_TECH_GATEWAY) {
+               ast_string_field_set(details, resultstr, "can't receive a fax on a channel with a T.38 gateway");
+               set_channel_variables(chan, details);
+               ast_log(LOG_ERROR, "executing ReceiveFAX on a channel with a T.38 Gateway is not supported\n");
+               ao2_ref(details, -1);
+               return -1;
+       }
+
        if (details->maxrate < details->minrate) {
                ast_string_field_set(details, error, "INVALID_ARGUMENTS");
                ast_string_field_set(details, resultstr, "maxrate is less than minrate");
@@ -1741,8 +1856,6 @@ static int sendfax_t38_init(struct ast_channel *chan, struct ast_fax_session_det
        struct ast_frame *frame = NULL;
        struct ast_control_t38_parameters t38_parameters;
 
-       t38_parameters_ast_to_fax(&details->our_t38_parameters, &our_t38_parameters);
-
        /* send CNG tone while listening for the receiver to initiate a switch
         * to T.38 mode; if they do, stop sending the CNG tone and proceed with
         * the switch.
@@ -1999,6 +2112,14 @@ static int sendfax_exec(struct ast_channel *chan, const char *data)
        ast_string_field_set(details, error, "INIT_ERROR");
        set_channel_variables(chan, details);
 
+       if (details->caps & AST_FAX_TECH_GATEWAY) {
+               ast_string_field_set(details, resultstr, "can't send a fax on a channel with a T.38 gateway");
+               set_channel_variables(chan, details);
+               ast_log(LOG_ERROR, "executing SendFAX on a channel with a T.38 Gateway is not supported\n");
+               ao2_ref(details, -1);
+               return -1;
+       }
+
        if (details->maxrate < details->minrate) {
                ast_string_field_set(details, error, "INVALID_ARGUMENTS");
                ast_string_field_set(details, resultstr, "maxrate is less than minrate");
@@ -2230,6 +2351,647 @@ static int sendfax_exec(struct ast_channel *chan, const char *data)
        return (!channel_alive) ? -1 : 0;
 }
 
+/*! \brief destroy a FAX gateway session structure */
+static void destroy_gateway(void *data)
+{
+       struct fax_gateway *gateway = data;
+
+       if (gateway->chan_dsp) {
+               ast_dsp_free(gateway->chan_dsp);
+               gateway->chan_dsp = NULL;
+       }
+
+       if (gateway->peer_dsp) {
+               ast_dsp_free(gateway->peer_dsp);
+               gateway->peer_dsp = NULL;
+       }
+
+       if (gateway->s) {
+               fax_session_release(gateway->s, gateway->token);
+               gateway->token = NULL;
+               gateway->s->details->caps |= ~AST_FAX_TECH_GATEWAY;
+
+               ao2_lock(faxregistry.container);
+               ao2_unlink(faxregistry.container, gateway->s);
+               ao2_unlock(faxregistry.container);
+
+               ao2_ref(gateway->s, -1);
+               gateway->s = NULL;
+       }
+}
+
+/*! \brief Create a new fax gateway object.
+ * \param details the fax session details
+ * \return NULL or a fax gateway object
+ */
+static struct fax_gateway *fax_gateway_new(struct ast_fax_session_details *details)
+{
+       struct fax_gateway *gateway = ao2_alloc(sizeof(*gateway), destroy_gateway);
+       if (!gateway) {
+               return NULL;
+       }
+
+       gateway->chan_dsp = ast_dsp_new();
+       if (!gateway->chan_dsp) {
+               ao2_ref(gateway, -1);
+               return NULL;
+       }
+
+       gateway->peer_dsp = ast_dsp_new();
+       if (!gateway->peer_dsp) {
+               ao2_ref(gateway, -1);
+               return NULL;
+       }
+
+       gateway->framehook = -1;
+
+       ast_dsp_set_features(gateway->chan_dsp, DSP_FEATURE_FAX_DETECT);
+       ast_dsp_set_faxmode(gateway->chan_dsp, DSP_FAXMODE_DETECT_CED);
+
+       ast_dsp_set_features(gateway->peer_dsp, DSP_FEATURE_FAX_DETECT);
+       ast_dsp_set_faxmode(gateway->peer_dsp, DSP_FAXMODE_DETECT_CED);
+
+       details->caps = AST_FAX_TECH_GATEWAY;
+       if (!(gateway->s = fax_session_reserve(details, &gateway->token))) {
+               details->caps |= ~AST_FAX_TECH_GATEWAY;
+               ast_log(LOG_ERROR, "Can't reserve a FAX session, gateway attempt failed.\n");
+               ao2_ref(gateway, -1);
+               return NULL;
+       }
+
+       return gateway;
+}
+
+/*! \brief Create a fax session and start T.30<->T.38 gateway mode
+ * \param gateway a fax gateway object
+ * \param details fax session details
+ * \param chan active channel
+ * \return 0 on error 1 on success*/
+static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session_details *details, struct ast_channel *chan)
+{
+       struct ast_fax_session *s;
+
+       /* create the FAX session */
+       if (!(s = fax_session_new(details, chan, gateway->s, gateway->token))) {
+               gateway->token = NULL;
+               ast_string_field_set(details, result, "FAILED");
+               ast_string_field_set(details, resultstr, "error starting gateway session");
+               ast_string_field_set(details, error, "INIT_ERROR");
+               set_channel_variables(chan, details);
+               report_fax_status(chan, details, "No Available Resource");
+               ast_log(LOG_ERROR, "Can't create a FAX session, gateway attempt failed.\n");
+               return -1;
+       }
+       /* release the reference for the reserved session and replace it with
+        * the real session */
+       ao2_ref(gateway->s, -1);
+       gateway->s = s;
+       gateway->token = NULL;
+
+       if (gateway->s->tech->start_session(gateway->s) < 0) {
+               ast_string_field_set(details, result, "FAILED");
+               ast_string_field_set(details, resultstr, "error starting gateway session");
+               ast_string_field_set(details, error, "INIT_ERROR");
+               set_channel_variables(chan, details);
+               return -1;
+       }
+
+       gateway->timeout_start.tv_sec = 0;
+       gateway->timeout_start.tv_usec = 0;
+
+       report_fax_status(chan, details, "FAX Transmission In Progress");
+
+       return 0;
+}
+
+static struct ast_frame *fax_gateway_detect_ced(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
+{
+       struct ast_frame *dfr = ast_frdup(f);
+       struct ast_dsp *active_dsp = (active == chan) ? gateway->chan_dsp : gateway->peer_dsp;
+       struct ast_channel *other = (active == chan) ? peer : chan;
+
+       if (!dfr) {
+               return f;
+       }
+
+       if (!(dfr = ast_dsp_process(active, active_dsp, dfr))) {
+               return f;
+       }
+
+       if (dfr->frametype == AST_FRAME_DTMF && dfr->subclass.integer == 'e') {
+               if (ast_channel_get_t38_state(other) == T38_STATE_UNKNOWN) {
+                       struct ast_control_t38_parameters t38_parameters = {
+                               .request_response = AST_T38_REQUEST_NEGOTIATE,
+                       };
+                       struct ast_frame control_frame = {
+                               .src = "res_fax",
+                               .frametype = AST_FRAME_CONTROL,
+                               .datalen = sizeof(t38_parameters),
+                               .subclass.integer = AST_CONTROL_T38_PARAMETERS,
+                               .data.ptr = &t38_parameters,
+                       };
+
+                       struct ast_fax_session_details *details = find_details(chan);
+                       ast_frfree(dfr);
+
+                       if (!details) {
+                               ast_log(LOG_ERROR, "no FAX session details found on chan %s for T.38 gateway session, odd\n", chan->name);
+                               ast_framehook_detach(chan, gateway->framehook);
+                               return f;
+                       }
+
+                       t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
+                       ao2_ref(details, -1);
+
+                       if (!(dfr = ast_frisolate(&control_frame))) {
+                               ast_log(LOG_ERROR, "error generating T.38 request control frame on chan %s for T.38 gateway session\n", chan->name);
+                               return f;
+                       }
+
+                       gateway->t38_state = T38_STATE_NEGOTIATING;
+                       gateway->timeout_start = ast_tvnow();
+
+                       ast_debug(1, "detected CED tone on %s, requesting T.38 on %s for T.38 gateway session\n", active->name, other->name);
+                       return dfr;
+               } else {
+                       ast_debug(1, "detected CED tone on %s, but %s does not support T.38 for T.38 gateway session\n", active->name, other->name);
+               }
+       }
+
+       ast_frfree(dfr);
+       return f;
+}
+
+static int fax_gateway_indicate_t38(struct ast_channel *chan, struct ast_channel *active, struct ast_control_t38_parameters *control_params)
+{
+       if (active == chan) {
+               return ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, control_params, sizeof(*control_params));
+       } else {
+               return ast_queue_control_data(chan, AST_CONTROL_T38_PARAMETERS, control_params, sizeof(*control_params));
+       }
+}
+
+/*! \brief T38 Gateway Negotiate t38 parameters
+ * \param gateway gateway object
+ * \param chan channel running the gateway
+ * \param peer channel im bridged too
+ * \param active channel the frame originated on
+ * \param f the control frame to process
+ * \return processed control frame or null frame
+ */
+static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
+{
+       struct ast_control_t38_parameters *control_params = f->data.ptr;
+       struct ast_channel *other = (active == chan) ? peer : chan;
+       struct ast_fax_session_details *details;
+
+       if (f->datalen != sizeof(struct ast_control_t38_parameters)) {
+               /* invalaid AST_CONTROL_T38_PARAMETERS frame, we can't
+                * do anything with it, pass it on */
+               return f;
+       }
+
+       /* ignore frames from ourselves */
+       if ((gateway->t38_state == T38_STATE_NEGOTIATED && control_params->request_response == AST_T38_NEGOTIATED)
+               || (gateway->t38_state == T38_STATE_REJECTED && control_params->request_response == AST_T38_REFUSED)
+               || (gateway->t38_state == T38_STATE_NEGOTIATING && control_params->request_response == AST_T38_REQUEST_TERMINATE)) {
+
+               return f;
+       }
+
+       if (!(details = find_details(chan))) {
+               ast_log(LOG_ERROR, "no FAX session details found on chan %s for T.38 gateway session, odd\n", chan->name);
+               ast_framehook_detach(chan, gateway->framehook);
+               return f;
+       }
+
+       if (control_params->request_response == AST_T38_REQUEST_NEGOTIATE) {
+               enum ast_t38_state state = ast_channel_get_t38_state(other);
+               if (state == T38_STATE_UNKNOWN) {
+                       /* we detected a request to negotiate T.38 and the
+                        * other channel appears to support T.38, we'll pass
+                        * the request through and only step in if the other
+                        * channel rejects the request */
+                       ast_debug(1, "%s is attempting to negotiate T.38 with %s, we'll see what happens\n", active->name, other->name);
+                       t38_parameters_ast_to_fax(&details->their_t38_parameters, control_params);
+                       gateway->t38_state = T38_STATE_UNKNOWN;
+                       gateway->timeout_start = ast_tvnow();
+                       ao2_ref(details, -1);
+                       return f;
+               } else if (state == T38_STATE_UNAVAILABLE || state == T38_STATE_REJECTED) {
+                       /* the other channel does not support T.38, we need to
+                        * step in here */
+                       ast_debug(1, "%s is attempting to negotiate T.38 but %s does not support it\n", active->name, other->name);
+                       ast_debug(1, "starting T.38 gateway for T.38 channel %s and G.711 channel %s\n", active->name, other->name);
+
+                       t38_parameters_ast_to_fax(&details->their_t38_parameters, control_params);
+                       t38_parameters_fax_to_ast(control_params, &details->our_t38_parameters);
+
+                       if (fax_gateway_start(gateway, details, chan)) {
+                               ast_log(LOG_ERROR, "error starting T.38 gateway for T.38 channel %s and G.711 channel %s\n", active->name, other->name);
+                               gateway->t38_state = T38_STATE_REJECTED;
+                               control_params->request_response = AST_T38_REFUSED;
+
+                               ast_framehook_detach(chan, details->gateway_id);
+                               details->gateway_id = -1;
+                       } else {
+                               gateway->t38_state = T38_STATE_NEGOTIATED;
+                               control_params->request_response = AST_T38_NEGOTIATED;
+                               report_fax_status(chan, details, "T.38 Negotiated");
+                       }
+
+                       fax_gateway_indicate_t38(chan, active, control_params);
+
+                       ao2_ref(details, -1);
+                       return &ast_null_frame;
+               } else if (gateway->t38_state == T38_STATE_NEGOTIATING) {
+                       /* we got a request to negotiate T.38 after we already
+                        * sent one to the other party based on CED tone
+                        * detection. We'll just pretend we passed this request
+                        * through in the first place. */
+
+                       t38_parameters_ast_to_fax(&details->their_t38_parameters, control_params);
+                       gateway->t38_state = T38_STATE_UNKNOWN;
+                       gateway->timeout_start = ast_tvnow();
+
+                       ast_debug(1, "%s is attempting to negotiate T.38 after we already sent a negotiation request based on CED detection\n", active->name);
+                       ao2_ref(details, -1);
+                       return &ast_null_frame;
+               } else if (gateway->t38_state == T38_STATE_NEGOTIATED) {
+                       /* we got a request to negotiate T.38 after we already
+                        * sent one to the other party based on CED tone
+                        * detection and received a response. We need to
+                        * respond to this and shut down the gateway. */
+
+                       t38_parameters_fax_to_ast(control_params, &details->their_t38_parameters);
+                       ast_framehook_detach(chan, details->gateway_id);
+                       details->gateway_id = -1;
+
+                       control_params->request_response = AST_T38_NEGOTIATED;
+
+                       fax_gateway_indicate_t38(chan, active, control_params);
+
+                       ast_string_field_set(details, result, "SUCCESS");
+                       ast_string_field_set(details, resultstr, "no gateway necessary");
+                       ast_string_field_set(details, error, "NATIVE_T38");
+                       set_channel_variables(chan, details);
+
+                       ast_debug(1, "%s is attempting to negotiate T.38 after we already negotiated T.38 with %s, disabling the gateway\n", active->name, other->name);
+                       ao2_ref(details, -1);
+                       return &ast_null_frame;
+               } else {
+                       ast_log(LOG_WARNING, "%s is attempting to negotiate T.38 while %s is in an unsupported state\n", active->name, other->name);
+                       ao2_ref(details, -1);
+                       return f;
+               }
+       } else if (gateway->t38_state == T38_STATE_NEGOTIATING
+               && control_params->request_response == AST_T38_REFUSED) {
+
+               ast_debug(1, "unable to negotiate T.38 on %s for fax gateway\n", active->name);
+
+               /* our request to negotiate T.38 was refused, if the other
+                * channel supports T.38, they might still reinvite and save
+                * the day.  Otherwise disable the gateway. */
+               if (ast_channel_get_t38_state(other) == T38_STATE_UNKNOWN) {
+                       gateway->t38_state = T38_STATE_UNAVAILABLE;
+               } else {
+                       ast_framehook_detach(chan, details->gateway_id);
+                       details->gateway_id = -1;
+
+                       ast_string_field_set(details, result, "FAILED");
+                       ast_string_field_set(details, resultstr, "unable to negotiate T.38");
+                       ast_string_field_set(details, error, "T38_NEG_ERROR");
+                       set_channel_variables(chan, details);
+               }
+
+               ao2_ref(details, -1);
+               return &ast_null_frame;
+       } else if (gateway->t38_state == T38_STATE_NEGOTIATING
+               && control_params->request_response == AST_T38_NEGOTIATED) {
+
+               ast_debug(1, "starting T.38 gateway for T.38 channel %s and G.711 channel %s\n", active->name, other->name);
+
+               t38_parameters_ast_to_fax(&details->their_t38_parameters, control_params);
+
+               if (fax_gateway_start(gateway, details, chan)) {
+                       ast_log(LOG_ERROR, "error starting T.38 gateway for T.38 channel %s and G.711 channel %s\n", active->name, other->name);
+                       gateway->t38_state = T38_STATE_NEGOTIATING;
+                       control_params->request_response = AST_T38_REQUEST_TERMINATE;
+
+                       fax_gateway_indicate_t38(chan, active, control_params);
+               } else {
+                       gateway->t38_state = T38_STATE_NEGOTIATED;
+                       report_fax_status(chan, details, "T.38 Negotiated");
+               }
+
+               ao2_ref(details, -1);
+               return &ast_null_frame;
+       } else if (control_params->request_response == AST_T38_REFUSED) {
+               /* the other channel refused the request to negotiate T.38,
+                * we'll step in here and pretend the request was accepted */
+
+               ast_debug(1, "%s attempted to negotiate T.38 but %s refused the request\n", other->name, active->name);
+               ast_debug(1, "starting T.38 gateway for T.38 channel %s and G.711 channel %s\n", other->name, active->name);
+
+               t38_parameters_fax_to_ast(control_params, &details->our_t38_parameters);
+
+               if (fax_gateway_start(gateway, details, chan)) {
+                       ast_log(LOG_ERROR, "error starting T.38 gateway for T.38 channel %s and G.711 channel %s\n", active->name, other->name);
+                       gateway->t38_state = T38_STATE_REJECTED;
+                       control_params->request_response = AST_T38_REFUSED;
+
+                       ast_framehook_detach(chan, details->gateway_id);
+                       details->gateway_id = -1;
+               } else {
+                       gateway->t38_state = T38_STATE_NEGOTIATED;
+                       control_params->request_response = AST_T38_NEGOTIATED;
+               }
+
+               ao2_ref(details, -1);
+               return f;
+       } else if (control_params->request_response == AST_T38_REQUEST_TERMINATE) {
+               /* the channel wishes to end our short relationship, we shall
+                * oblige */
+
+               ast_debug(1, "T.38 channel %s is requesting a shutdown of T.38, disabling the gateway\n", active->name);
+
+               ast_framehook_detach(chan, details->gateway_id);
+               details->gateway_id = -1;
+
+               gateway->t38_state = T38_STATE_REJECTED;
+               control_params->request_response = AST_T38_TERMINATED;
+
+               fax_gateway_indicate_t38(chan, active, control_params);
+
+               ao2_ref(details, -1);
+               return &ast_null_frame;
+       } else if (control_params->request_response == AST_T38_NEGOTIATED) {
+               ast_debug(1, "T.38 successfully negotiated between %s and %s, no gateway necessary\n", active->name, other->name);
+
+               ast_framehook_detach(chan, details->gateway_id);
+               details->gateway_id = -1;
+
+               ast_string_field_set(details, result, "SUCCESS");
+               ast_string_field_set(details, resultstr, "no gateway necessary");
+               ast_string_field_set(details, error, "NATIVE_T38");
+               set_channel_variables(chan, details);
+
+               ao2_ref(details, -1);
+               return f;
+       } else if (control_params->request_response == AST_T38_TERMINATED) {
+               ast_debug(1, "T.38 disabled on channel %s\n", active->name);
+
+               ast_framehook_detach(chan, details->gateway_id);
+               details->gateway_id = -1;
+
+               ao2_ref(details, -1);
+               return &ast_null_frame;
+       }
+
+       ao2_ref(details, -1);
+       return f;
+}
+
+/*! \brief Destroy the gateway data structure when the framehook is detached
+ * \param data framehook data (gateway data)*/
+static void fax_gateway_framehook_destroy(void *data) {
+       struct fax_gateway *gateway = data;
+
+       if (gateway->s) {
+               switch (gateway->s->state) {
+               case AST_FAX_STATE_INITIALIZED:
+               case AST_FAX_STATE_OPEN:
+               case AST_FAX_STATE_ACTIVE:
+               case AST_FAX_STATE_COMPLETE:
+                       if (gateway->s->tech->cancel_session) {
+                               gateway->s->tech->cancel_session(gateway->s);
+                       }
+                       /* fall through */
+               default:
+                       break;
+               }
+       }
+
+       ao2_ref(gateway, -1);
+}
+
+/*! \brief T.30<->T.38 gateway framehook.
+ *
+ * Intercept packets on bridged channels and determine if a T.38 gateway is
+ * required. If a gateway is required, start a gateway and handle T.38
+ * negotiation if necessary.
+ *
+ * \param chan channel running the gateway
+ * \param f frame to handle may be NULL
+ * \param event framehook event
+ * \param data framehook data (struct fax_gateway *)
+ *
+ * \return processed frame or NULL when f is NULL or a null frame
+ */
+static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct ast_frame *f, enum ast_framehook_event event, void *data) {
+       struct fax_gateway *gateway = data;
+       struct ast_channel *peer, *active;
+
+       /* restore audio formats when we are detached */
+       if (event == AST_FRAMEHOOK_EVENT_DETACHED) {
+               set_channel_variables(chan, gateway->s->details);
+
+               if (gateway->bridged) {
+                       ast_set_read_format(chan, &gateway->chan_read_format);
+                       ast_set_read_format(chan, &gateway->chan_write_format);
+
+                       if ((peer = ast_bridged_channel(chan))) {
+                               ast_set_read_format(peer, &gateway->peer_read_format);
+                               ast_set_read_format(peer, &gateway->peer_write_format);
+                               ast_channel_make_compatible(chan, peer);
+                       }
+               }
+
+               return NULL;
+       }
+
+       if (!f || (event == AST_FRAMEHOOK_EVENT_ATTACHED)) {
+               return NULL;
+       };
+
+       /* this frame was generated by the fax gateway, pass it on */
+       if (ast_test_flag(f, AST_FAX_FRFLAG_GATEWAY)) {
+               return f;
+       }
+
+       if (!(peer = ast_bridged_channel(chan))) {
+               /* not bridged, don't do anything */
+               return f;
+       }
+
+       if (!gateway->bridged && peer) {
+               /* don't start a gateway if neither channel can handle T.38 */
+               if (ast_channel_get_t38_state(chan) == T38_STATE_UNAVAILABLE && ast_channel_get_t38_state(peer) == T38_STATE_UNAVAILABLE) {
+                       ast_debug(1, "not starting gateway for %s and %s; neither channel supports T.38\n", chan->name, peer->name);
+                       ast_framehook_detach(chan, gateway->framehook);
+                       gateway->s->details->gateway_id = -1;
+
+                       ast_string_field_set(gateway->s->details, result, "FAILED");
+                       ast_string_field_set(gateway->s->details, resultstr, "neither channel supports T.38");
+                       ast_string_field_set(gateway->s->details, error, "T38_NEG_ERROR");
+                       set_channel_variables(chan, gateway->s->details);
+                       return f;
+               }
+
+               gateway->timeout_start = ast_tvnow();
+
+               /* we are bridged, change r/w formats to SLIN for CED detection and T.30 */
+               ast_format_copy(&gateway->chan_read_format, &chan->readformat);
+               ast_format_copy(&gateway->chan_write_format, &chan->readformat);
+
+               ast_format_copy(&gateway->peer_read_format, &peer->readformat);
+               ast_format_copy(&gateway->peer_write_format, &peer->readformat);
+
+               ast_set_read_format_by_id(chan, AST_FORMAT_SLINEAR);
+               ast_set_write_format_by_id(chan, AST_FORMAT_SLINEAR);
+
+               ast_set_read_format_by_id(peer, AST_FORMAT_SLINEAR);
+               ast_set_write_format_by_id(peer, AST_FORMAT_SLINEAR);
+
+               ast_channel_make_compatible(chan, peer);
+               gateway->bridged = 1;
+       }
+
+       if (gateway->bridged && !ast_tvzero(gateway->timeout_start)) {
+               if (ast_tvdiff_ms(ast_tvnow(), gateway->timeout_start) > FAX_GATEWAY_TIMEOUT) {
+                       ast_debug(1, "no fax activity between %s and %s after %d ms, disabling gateway\n", chan->name, peer->name, FAX_GATEWAY_TIMEOUT);
+                       ast_framehook_detach(chan, gateway->framehook);
+                       gateway->s->details->gateway_id = -1;
+
+                       ast_string_field_set(gateway->s->details, result, "FAILED");
+                       ast_string_field_build(gateway->s->details, resultstr, "no fax activity after %d ms", FAX_GATEWAY_TIMEOUT);
+                       ast_string_field_set(gateway->s->details, error, "TIMEOUT");
+                       set_channel_variables(chan, gateway->s->details);
+                       return f;
+               }
+       }
+
+       /* only handle VOICE, MODEM, and CONTROL frames*/
+       switch (f->frametype) {
+       case AST_FRAME_VOICE:
+               switch (f->subclass.format.id) {
+               case AST_FORMAT_SLINEAR:
+               case AST_FORMAT_ALAW:
+               case AST_FORMAT_ULAW:
+                       break;
+               default:
+                       return f;
+               }
+               break;
+       case AST_FRAME_MODEM:
+               if (f->subclass.integer == AST_MODEM_T38) {
+                       break;
+               }
+               return f;
+       case AST_FRAME_CONTROL:
+               if (f->subclass.integer == AST_CONTROL_T38_PARAMETERS) {
+                       break;
+               }
+               return f;
+       default:
+               return f;
+       }
+
+       /* detect the active channel */
+       switch (event) {
+       case AST_FRAMEHOOK_EVENT_WRITE:
+               active = peer;
+               break;
+       case AST_FRAMEHOOK_EVENT_READ:
+               active = chan;
+               break;
+       default:
+               ast_log(LOG_WARNING, "unhandled framehook event %i\n", event);
+               return f;
+       }
+
+       /* handle control frames */
+       if (f->frametype == AST_FRAME_CONTROL && f->subclass.integer == AST_CONTROL_T38_PARAMETERS) {
+               return fax_gateway_detect_t38(gateway, chan, peer, active, f);
+       }
+
+       /* not in gateway mode yet, listen for CED */
+       /* XXX this should detect a v21 preamble instead of CED */
+       if (gateway->t38_state == T38_STATE_UNAVAILABLE && f->frametype == AST_FRAME_VOICE) {
+               return fax_gateway_detect_ced(gateway, chan, peer, active, f);
+       }
+
+       /* in gateway mode, gateway some packets */
+       if (gateway->t38_state == T38_STATE_NEGOTIATED) {
+               /* framehooks are called in __ast_read() before frame format
+                * translation is does, so we need to translate here */
+               if ((f->frametype == AST_FRAME_VOICE) && (f->subclass.format.id != AST_FORMAT_SLINEAR)) {
+                       if (active->readtrans && (f = ast_translate(active->readtrans, f, 1)) == NULL) {
+                               f = &ast_null_frame;
+                               return f;
+                       }
+               }
+
+               /* XXX we ignore the return value here, perhaps we should
+                * disable the gateway if a write fails. I am not sure how a
+                * write would fail, or even if a failure would be fatal so for
+                * now we'll just ignore the return value. */
+               gateway->s->tech->write(gateway->s, f);
+               f = &ast_null_frame;
+               return f;
+       }
+
+       return f;
+}
+
+/*! \brief Attach a gateway framehook object to a channel.
+ * \param chan the channel to attach to
+ * \param details fax session details
+ * \return the framehook id of the attached framehook or -1 on error
+ * \retval -1 error
+ */
+static int fax_gateway_attach(struct ast_channel *chan, struct ast_fax_session_details *details)
+{
+       struct fax_gateway *gateway;
+       struct ast_framehook_interface fr_hook = {
+               .version = AST_FRAMEHOOK_INTERFACE_VERSION,
+               .event_cb = fax_gateway_framehook,
+               .destroy_cb = fax_gateway_framehook_destroy,
+       };
+
+       ast_string_field_set(details, result, "SUCCESS");
+       ast_string_field_set(details, resultstr, "gateway operation started successfully");
+       ast_string_field_set(details, error, "NO_ERROR");
+       set_channel_variables(chan, details);
+
+       /* set up the frame hook*/
+       gateway = fax_gateway_new(details);
+       if (!gateway) {
+               ast_string_field_set(details, result, "FAILED");
+               ast_string_field_set(details, resultstr, "error initializing gateway session");
+               ast_string_field_set(details, error, "INIT_ERROR");
+               set_channel_variables(chan, details);
+               report_fax_status(chan, details, "No Available Resource");
+               return -1;
+       }
+
+       fr_hook.data = gateway;
+       ast_channel_lock(chan);
+       gateway->framehook = ast_framehook_attach(chan, &fr_hook);
+       ast_channel_unlock(chan);
+
+       if (gateway->framehook < 0) {
+               ao2_ref(gateway, -1);
+               ast_string_field_set(details, result, "FAILED");
+               ast_string_field_set(details, resultstr, "error attaching gateway to channel");
+               ast_string_field_set(details, error, "INIT_ERROR");
+               set_channel_variables(chan, details);
+               return -1;
+       }
+
+       return gateway->framehook;
+}
+
 /*! \brief hash callback for ao2 */
 static int session_hash_cb(const void *obj, const int flags)
 {
@@ -2501,19 +3263,15 @@ static char *cli_fax_show_sessions(struct ast_cli_entry *e, int cmd, struct ast_
        while ((s = ao2_iterator_next(&i))) {
                ao2_lock(s);
 
-               if (!(filenames = generate_filenames_string(s->details, "", ", "))) {
-                       ast_log(LOG_ERROR, "error printing filenames for 'fax show sessions' command");
-                       ao2_unlock(s);
-                       ao2_ref(s, -1);
-                       ao2_iterator_destroy(&i);
-                       return CLI_FAILURE;
-               }
+               filenames = generate_filenames_string(s->details, "", ", ");
 
                ast_cli(a->fd, "%-20.20s %-10.10s %-10d %-5.5s %-10.10s %-15.15s %-30s\n",
                        s->channame, s->tech->type, s->id,
                        (s->details->caps & AST_FAX_TECH_AUDIO) ? "G.711" : "T.38",
-                       (s->details->caps & AST_FAX_TECH_SEND) ? "send" : "receive",
-                       ast_fax_state_to_str(s->state), filenames);
+                       (s->details->caps & AST_FAX_TECH_GATEWAY)
+                               ? "gateway"
+                               : (s->details->caps & AST_FAX_TECH_SEND) ? "send" : "receive",
+                       ast_fax_state_to_str(s->state), S_OR(filenames, ""));
 
                ast_free(filenames);
                ao2_unlock(s);
@@ -2626,6 +3384,9 @@ static int acf_faxopt_read(struct ast_channel *chan, const char *cmd, char *data
        }
        if (!strcasecmp(data, "ecm")) {
                ast_copy_string(buf, details->option.ecm ? "yes" : "no", len);
+       } else if (!strcasecmp(data, "t38gateway") || !strcasecmp(data, "gateway") ||
+                  !strcasecmp(data, "t38_gateway") || !strcasecmp(data, "faxgateway")) {
+               ast_copy_string(buf, details->gateway_id != -1 ? "yes" : "no", len);
        } else if (!strcasecmp(data, "error")) {
                ast_copy_string(buf, details->error, len);
        } else if (!strcasecmp(data, "filename")) {
@@ -2700,6 +3461,27 @@ static int acf_faxopt_write(struct ast_channel *chan, const char *cmd, char *dat
                } else {
                        ast_log(LOG_WARNING, "Unsupported value '%s' passed to FAXOPT(ecm).\n", value);
                }
+       } else if (!strcasecmp(data, "t38gateway") || !strcasecmp(data, "gateway") ||
+                  !strcasecmp(data, "t38_gateway") || !strcasecmp(data, "faxgateway")) {
+               const char *val = ast_skip_blanks(value);
+               if (ast_true(val)) {
+                       if (details->gateway_id < 0) {
+                               details->gateway_id = fax_gateway_attach(chan, details);
+                               if (details->gateway_id < 0) {
+                                       ast_log(LOG_ERROR, "Error attaching T.38 gateway to channel %s.\n", chan->name);
+                                       res = -1;
+                               } else {
+                                       ast_debug(1, "Attached T.38 gateway to channel %s.\n", chan->name);
+                               }
+                       } else {
+                               ast_log(LOG_WARNING, "Attempt to attach a T.38 gateway on channel (%s) with gateway already running.\n", chan->name);
+                       }
+               } else if (ast_false(val)) {
+                       ast_framehook_detach(chan, details->gateway_id);
+                       details->gateway_id = -1;
+               } else {
+                       ast_log(LOG_WARNING, "Unsupported value '%s' passed to FAXOPT(%s).\n", value, data);
+               }
        } else if (!strcasecmp(data, "headerinfo")) {
                ast_string_field_set(details, headerinfo, value);
        } else if (!strcasecmp(data, "localstationid")) {
@@ -2789,6 +3571,7 @@ static int load_module(void)
                ao2_ref(faxregistry.container, -1);
                return AST_MODULE_LOAD_DECLINE;
        }
+
        ast_cli_register_multiple(fax_cli, ARRAY_LEN(fax_cli));
        res = ast_custom_function_register(&acf_faxopt);        
        fax_logger_level = ast_logger_register_level("FAX");
index 851382b..9ecd783 100644 (file)
@@ -5,6 +5,22 @@
  *
  * Matthew Nicholson <mnicholson@digium.com>
  *
+ * Initial T.38-gateway code
+ * 2008, Daniel Ferenci <daniel.ferenci@nethemba.com>
+ * Created by Nethemba s.r.o. http://www.nethemba.com
+ * Sponsored by IPEX a.s. http://www.ipex.cz
+ *
+ * T.38-gateway integration into asterisk app_fax and rework
+ * 2008, Gregory Hinton Nietsky <gregory@dnstelecom.co.za>
+ * dns Telecom http://www.dnstelecom.co.za
+ *
+ * Modified to make T.38-gateway compatible with Asterisk 1.6.2
+ * 2010, Anton Verevkin <mymail@verevkin.it>
+ * ViaNetTV http://www.vianettv.com
+ *
+ * Modified to make T.38-gateway work
+ * 2010, Klaus Darilion, IPCom GmbH, www.ipcom.at
+ *
  * See http://www.asterisk.org for more information about
  * the Asterisk project. Please do not directly contact
  * any of the maintainers of this project for assistance;
@@ -46,9 +62,11 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/timing.h"
 #include "asterisk/astobj2.h"
 #include "asterisk/res_fax.h"
+#include "asterisk/channel.h"
 
 #define SPANDSP_FAX_SAMPLES 160
 #define SPANDSP_FAX_TIMER_RATE 8000 / SPANDSP_FAX_SAMPLES      /* 50 ticks per second, 20ms, 160 samples per second */
+#define SPANDSP_ENGAGE_UDPTL_NAT_RETRY 3
 
 static void *spandsp_fax_new(struct ast_fax_session *s, struct ast_fax_tech_token *token);
 static void spandsp_fax_destroy(struct ast_fax_session *s);
@@ -57,6 +75,9 @@ static int spandsp_fax_write(struct ast_fax_session *s, const struct ast_frame *
 static int spandsp_fax_start(struct ast_fax_session *s);
 static int spandsp_fax_cancel(struct ast_fax_session *s);
 static int spandsp_fax_switch_to_t38(struct ast_fax_session *s);
+static int spandsp_fax_gateway_start(struct ast_fax_session *s);
+static int spandsp_fax_gateway_process(struct ast_fax_session *s, const struct ast_frame *f);
+static void spandsp_fax_gateway_cleanup(struct ast_fax_session *s);
 
 static char *spandsp_fax_cli_show_capabilities(int fd);
 static char *spandsp_fax_cli_show_session(struct ast_fax_session *s, int fd);
@@ -75,7 +96,7 @@ static struct ast_fax_tech spandsp_fax_tech = {
         */
        .version = "pre-20090220",
 #endif
-       .caps = AST_FAX_TECH_AUDIO | AST_FAX_TECH_T38 | AST_FAX_TECH_SEND | AST_FAX_TECH_RECEIVE,
+       .caps = AST_FAX_TECH_AUDIO | AST_FAX_TECH_T38 | AST_FAX_TECH_SEND | AST_FAX_TECH_RECEIVE | AST_FAX_TECH_GATEWAY,
        .new_session = spandsp_fax_new,
        .destroy_session = spandsp_fax_destroy,
        .read = spandsp_fax_read,
@@ -114,6 +135,7 @@ static struct {
 struct spandsp_pvt {
        unsigned int ist38:1;
        unsigned int isdone:1;
+       enum ast_t38_state ast_t38_state;
        fax_state_t fax_state;
        t38_terminal_state_t t38_state;
        t30_state_t *t30_state;
@@ -121,6 +143,9 @@ struct spandsp_pvt {
 
        struct spandsp_fax_stats *stats;
 
+       struct spandsp_fax_gw_stats *t38stats;
+       t38_gateway_state_t t38_gw_state;
+
        struct ast_timer *timer;
        AST_LIST_HEAD(frame_queue, ast_frame) read_frames;
 };
@@ -158,7 +183,9 @@ static void session_destroy(struct spandsp_pvt *p)
  */
 static int t38_tx_packet_handler(t38_core_state_t *t38_core_state, void *data, const uint8_t *buf, int len, int count)
 {
-       struct spandsp_pvt *p = data;
+       int res = -1;
+       struct ast_fax_session *s = data;
+       struct spandsp_pvt *p = s->tech_pvt;
        struct ast_frame fax_frame = {
                .frametype = AST_FRAME_MODEM,
                .subclass.integer = AST_MODEM_T38,
@@ -174,13 +201,23 @@ static int t38_tx_packet_handler(t38_core_state_t *t38_core_state, void *data, c
        AST_FRAME_SET_BUFFER(f, buf, 0, len);
 
        if (!(f = ast_frisolate(f))) {
-               return -1;
+               return res;
        }
 
-       /* no need to lock, this all runs in the same thread */
-       AST_LIST_INSERT_TAIL(&p->read_frames, f, frame_list);
+       if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+               ast_set_flag(f, AST_FAX_FRFLAG_GATEWAY);
+               if (p->ast_t38_state == T38_STATE_NEGOTIATED) {
+                       res = ast_write(s->chan, f);
+               } else {
+                       res = ast_queue_frame(s->chan, f);
+               }
+               ast_frfree(f);
+       } else {
+               /* no need to lock, this all runs in the same thread */
+               AST_LIST_INSERT_TAIL(&p->read_frames, f, frame_list);
+       }
 
-       return 0;
+       return res;
 }
 
 static int update_stats(struct spandsp_pvt *p, int completion_code)
@@ -422,6 +459,11 @@ static void *spandsp_fax_new(struct ast_fax_session *s, struct ast_fax_tech_toke
                goto e_return;
        }
 
+       if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+               s->state = AST_FAX_STATE_INITIALIZED;
+               return p;
+       }
+
        AST_LIST_HEAD_INIT(&p->read_frames);
 
        if (s->details->caps & AST_FAX_TECH_RECEIVE) {
@@ -450,7 +492,7 @@ static void *spandsp_fax_new(struct ast_fax_session *s, struct ast_fax_tech_toke
                }
 
                /* init t38 stuff */
-               t38_terminal_init(&p->t38_state, caller_mode, t38_tx_packet_handler, p);
+               t38_terminal_init(&p->t38_state, caller_mode, t38_tx_packet_handler, s);
                set_logging(&p->t38_state.logging, s->details);
        }
 
@@ -475,7 +517,12 @@ static void spandsp_fax_destroy(struct ast_fax_session *s)
 {
        struct spandsp_pvt *p = s->tech_pvt;
 
-       session_destroy(p);
+       if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+               spandsp_fax_gateway_cleanup(s);
+       } else {
+               session_destroy(p);
+       }
+
        ast_free(p);
        s->tech_pvt = NULL;
        s->fd = -1;
@@ -536,6 +583,10 @@ static int spandsp_fax_write(struct ast_fax_session *s, const struct ast_frame *
 {
        struct spandsp_pvt *p = s->tech_pvt;
 
+       if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+               return spandsp_fax_gateway_process(s, f);
+       }
+
        /* XXX do we need to lock here? */
        if (s->state == AST_FAX_STATE_COMPLETE) {
                ast_log(LOG_WARNING, "FAX session '%d' is in the '%s' state.\n", s->id, ast_fax_state_to_str(s->state));
@@ -549,6 +600,182 @@ static int spandsp_fax_write(struct ast_fax_session *s, const struct ast_frame *
        }
 }
 
+/*! \brief generate T.30 packets sent to the T.30 leg of gateway
+ * \param chan T.30 channel
+ * \param data fax session structure
+ * \param len not used
+ * \param samples no of samples generated
+ * \return -1 on failure or 0 on sucess*/
+static int spandsp_fax_gw_t30_gen(struct ast_channel *chan, void *data, int len, int samples)
+{
+       int res = -1;
+       struct ast_fax_session *s = data;
+       struct spandsp_pvt *p = s->tech_pvt;
+       uint8_t buffer[AST_FRIENDLY_OFFSET + samples * sizeof(uint16_t)];
+       struct ast_frame *f;
+       struct ast_frame t30_frame = {
+               .frametype = AST_FRAME_VOICE,
+               .src = "res_fax_spandsp_g711",
+               .samples = samples,
+               .flags = AST_FAX_FRFLAG_GATEWAY,
+       };
+
+       AST_FRAME_SET_BUFFER(&t30_frame, buffer, AST_FRIENDLY_OFFSET, t30_frame.samples * sizeof(int16_t));
+
+       ast_format_set(&t30_frame.subclass.format, AST_FORMAT_SLINEAR, 0);
+       if (!(f = ast_frisolate(&t30_frame))) {
+               return p->isdone ? -1 : res;
+       }
+
+       /* generate a T.30 packet */
+       if ((f->samples = t38_gateway_tx(&p->t38_gw_state, f->data.ptr, f->samples))) {
+               f->datalen = f->samples * sizeof(int16_t);
+               res = ast_write(chan, f);
+       }
+       ast_frfree(f);
+       return p->isdone ? -1 : res;
+}
+
+/*! \brief simple routine to allocate data to generator
+ * \param chan channel
+ * \param params generator data
+ * \return data to use in generator call*/
+static void *spandsp_fax_gw_gen_alloc(struct ast_channel *chan, void *params) {
+       ao2_ref(params, +1);
+       return params;
+}
+
+static void spandsp_fax_gw_gen_release(struct ast_channel *chan, void *data) {
+       ao2_ref(data, -1);
+}
+
+/*! \brief activate a spandsp gateway based on the information in the given fax session
+ * \param s fax session
+ * \return -1 on error 0 on sucess*/
+static int spandsp_fax_gateway_start(struct ast_fax_session *s) {
+       struct spandsp_pvt *p = s->tech_pvt;
+       struct ast_fax_t38_parameters *t38_param;
+       int i, modems = 0;
+       struct ast_channel *peer;
+       static struct ast_generator t30_gen = {
+               alloc: spandsp_fax_gw_gen_alloc,
+               release: spandsp_fax_gw_gen_release,
+               generate: spandsp_fax_gw_t30_gen,
+       };
+
+#if SPANDSP_RELEASE_DATE >= 20081012
+       /* for spandsp shaphots 0.0.6 and higher */
+       p->t38_core_state=&p->t38_gw_state.t38x.t38;
+#else
+       /* for spandsp release 0.0.5 */
+       p->t38_core_state=&p->t38_gw_state.t38;
+#endif
+
+       if (!t38_gateway_init(&p->t38_gw_state, t38_tx_packet_handler, s)) {
+               return -1;
+       }
+
+       p->ist38 = 1;
+       p->ast_t38_state = ast_channel_get_t38_state(s->chan);
+       if (!(peer = ast_bridged_channel(s->chan))) {
+               ast_channel_unlock(s->chan);
+               return -1;
+       }
+       ast_activate_generator(p->ast_t38_state == T38_STATE_NEGOTIATED ? peer : s->chan, &t30_gen , s);
+
+       set_logging(&p->t38_gw_state.logging, s->details);
+       set_logging(&p->t38_core_state->logging, s->details);
+
+       t38_param = (p->ast_t38_state == T38_STATE_NEGOTIATED) ? &s->details->our_t38_parameters : &s->details->their_t38_parameters;
+       t38_set_t38_version(p->t38_core_state, t38_param->version);
+       t38_gateway_set_ecm_capability(&p->t38_gw_state, s->details->option.ecm);
+       t38_set_max_datagram_size(p->t38_core_state, t38_param->max_ifp);
+       t38_set_fill_bit_removal(p->t38_core_state, t38_param->fill_bit_removal);
+       t38_set_mmr_transcoding(p->t38_core_state, t38_param->transcoding_mmr);
+       t38_set_jbig_transcoding(p->t38_core_state, t38_param->transcoding_jbig);
+       t38_set_data_rate_management_method(p->t38_core_state, 
+                       (t38_param->rate_management == AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF)? 1 : 2);
+
+       t38_gateway_set_transmit_on_idle(&p->t38_gw_state, TRUE);
+       t38_set_sequence_number_handling(p->t38_core_state, TRUE);
+
+       if (AST_FAX_MODEM_V17 & s->details->modems) {
+               modems |= T30_SUPPORT_V17;
+       }
+       if (AST_FAX_MODEM_V27 & s->details->modems) {
+               modems |= T30_SUPPORT_V27TER;
+       }
+       if (AST_FAX_MODEM_V29 & s->details->modems) {
+               modems |= T30_SUPPORT_V29;
+       }
+       if (AST_FAX_MODEM_V34 & s->details->modems) {
+#if defined(T30_SUPPORT_V34)
+               modems |= T30_SUPPORT_V34;
+#elif defined(T30_SUPPORT_V34HDX)
+               modems |= T30_SUPPORT_V34HDX;
+#else
+               ast_log(LOG_WARNING, "v34 not supported in this version of spandsp\n");
+#endif
+       }
+
+       t38_gateway_set_supported_modems(&p->t38_gw_state, modems);
+
+       /* engage udptl nat on other side of T38 line 
+        * (Asterisk changes media ports thus we send a few packets to reinitialize
+        * pinholes in NATs and FWs
+        */
+       for (i=0; i < SPANDSP_ENGAGE_UDPTL_NAT_RETRY; i++) {
+#if SPANDSP_RELEASE_DATE >= 20091228
+               t38_core_send_indicator(&p->t38_gw_state.t38x.t38, T38_IND_NO_SIGNAL);
+#elif SPANDSP_RELEASE_DATE >= 20081012
+               t38_core_send_indicator(&p->t38_gw_state.t38x.t38, T38_IND_NO_SIGNAL, p->t38_gw_state.t38x.t38.indicator_tx_count);
+#else
+               t38_core_send_indicator(&p->t38_gw_state.t38, T38_IND_NO_SIGNAL, p->t38_gw_state.t38.indicator_tx_count);
+#endif
+       }
+
+       s->state = AST_FAX_STATE_ACTIVE;
+
+       return 0;
+}
+
+/*! \brief process a frame from the bridge
+ * \param s fax session
+ * \param f frame to process
+ * \return 1 on sucess 0 on incorect packet*/
+static int spandsp_fax_gateway_process(struct ast_fax_session *s, const struct ast_frame *f)
+{
+       struct spandsp_pvt *p = s->tech_pvt;
+
+       /*invalid frame*/
+       if (!f->data.ptr || !f->datalen) {
+               return -1;
+       }
+
+       /* Process a IFP packet */
+       if ((f->frametype == AST_FRAME_MODEM) && (f->subclass.integer == AST_MODEM_T38)) {
+               return t38_core_rx_ifp_packet(p->t38_core_state, f->data.ptr, f->datalen, f->seqno);
+       } else if ((f->frametype == AST_FRAME_VOICE) && (f->subclass.format.id == AST_FORMAT_SLINEAR)) {
+               return t38_gateway_rx(&p->t38_gw_state, f->data.ptr, f->samples);
+       }
+
+       return -1;
+}
+
+/*! \brief gather data and clean up after gateway ends
+ * \param s fax session*/
+static void spandsp_fax_gateway_cleanup(struct ast_fax_session *s)
+{
+       struct spandsp_pvt *p = s->tech_pvt;
+       t38_stats_t t38_stats;
+
+       t38_gateway_get_transfer_statistics(&p->t38_gw_state, &t38_stats);
+
+       s->details->option.ecm = t38_stats.error_correcting_mode ? AST_FAX_OPTFLAG_TRUE : AST_FAX_OPTFLAG_FALSE;
+       s->details->pages_transferred = t38_stats.pages_transferred;
+       ast_string_field_build(s->details, transfer_rate, "%d", t38_stats.bit_rate);
+}
+
 /*! \brief */
 static int spandsp_fax_start(struct ast_fax_session *s)
 {
@@ -556,6 +783,10 @@ static int spandsp_fax_start(struct ast_fax_session *s)
 
        s->state = AST_FAX_STATE_OPEN;
 
+       if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+               return spandsp_fax_gateway_start(s);
+       }
+
        if (p->ist38) {
 #if SPANDSP_RELEASE_DATE >= 20080725
                /* for spandsp shaphots 0.0.6 and higher */
@@ -625,6 +856,12 @@ static int spandsp_fax_start(struct ast_fax_session *s)
 static int spandsp_fax_cancel(struct ast_fax_session *s)
 {
        struct spandsp_pvt *p = s->tech_pvt;
+
+       if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+               p->isdone = 1;
+               return 0;
+       }
+
        t30_terminate(p->t30_state);
        p->isdone = 1;
        return 0;
@@ -653,7 +890,7 @@ static int spandsp_fax_switch_to_t38(struct ast_fax_session *s)
 /*! \brief */
 static char *spandsp_fax_cli_show_capabilities(int fd)
 {
-       ast_cli(fd, "SEND RECEIVE T.38 G.711\n\n");
+       ast_cli(fd, "SEND RECEIVE T.38 G.711 GATEWAY\n\n");
        return  CLI_SUCCESS;
 }
 
@@ -661,35 +898,48 @@ static char *spandsp_fax_cli_show_capabilities(int fd)
 static char *spandsp_fax_cli_show_session(struct ast_fax_session *s, int fd)
 {
        struct spandsp_pvt *p = s->tech_pvt;
-       t30_stats_t stats;
 
        ao2_lock(s);
-       ast_cli(fd, "%-22s : %d\n", "session", s->id);
-       ast_cli(fd, "%-22s : %s\n", "operation", (s->details->caps & AST_FAX_TECH_RECEIVE) ? "Receive" : "Transmit");
-       ast_cli(fd, "%-22s : %s\n", "state", ast_fax_state_to_str(s->state));
-       if (s->state != AST_FAX_STATE_UNINITIALIZED) {
-               t30_get_transfer_statistics(p->t30_state, &stats);
-               ast_cli(fd, "%-22s : %s\n", "Last Status", t30_completion_code_to_str(stats.current_status));
-               ast_cli(fd, "%-22s : %s\n", "ECM Mode", stats.error_correcting_mode ? "Yes" : "No");
-               ast_cli(fd, "%-22s : %d\n", "Data Rate", stats.bit_rate);
-               ast_cli(fd, "%-22s : %dx%d\n", "Image Resolution", stats.x_resolution, stats.y_resolution);
+       if (s->details->caps & AST_FAX_TECH_GATEWAY) {
+               ast_cli(fd, "%-22s : %d\n", "session", s->id);
+               ast_cli(fd, "%-22s : %s\n", "operation", "Gateway");
+               ast_cli(fd, "%-22s : %s\n", "state", ast_fax_state_to_str(s->state));
+               if (s->state != AST_FAX_STATE_UNINITIALIZED) {
+                       t38_stats_t stats;
+                       t38_gateway_get_transfer_statistics(&p->t38_gw_state, &stats);
+                       ast_cli(fd, "%-22s : %s\n", "ECM Mode", stats.error_correcting_mode ? "Yes" : "No");
+                       ast_cli(fd, "%-22s : %d\n", "Data Rate", stats.bit_rate);
+                       ast_cli(fd, "%-22s : %d\n", "Page Number", stats.pages_transferred + 1);
+               }
+       } else {
+               ast_cli(fd, "%-22s : %d\n", "session", s->id);
+               ast_cli(fd, "%-22s : %s\n", "operation", (s->details->caps & AST_FAX_TECH_RECEIVE) ? "Receive" : "Transmit");
+               ast_cli(fd, "%-22s : %s\n", "state", ast_fax_state_to_str(s->state));
+               if (s->state != AST_FAX_STATE_UNINITIALIZED) {
+                       t30_stats_t stats;
+                       t30_get_transfer_statistics(p->t30_state, &stats);
+                       ast_cli(fd, "%-22s : %s\n", "Last Status", t30_completion_code_to_str(stats.current_status));
+                       ast_cli(fd, "%-22s : %s\n", "ECM Mode", stats.error_correcting_mode ? "Yes" : "No");
+                       ast_cli(fd, "%-22s : %d\n", "Data Rate", stats.bit_rate);
+                       ast_cli(fd, "%-22s : %dx%d\n", "Image Resolution", stats.x_resolution, stats.y_resolution);
 #if SPANDSP_RELEASE_DATE >= 20090220
-               ast_cli(fd, "%-22s : %d\n", "Page Number", ((s->details->caps & AST_FAX_TECH_RECEIVE) ? stats.pages_rx : stats.pages_tx) + 1);
+                       ast_cli(fd, "%-22s : %d\n", "Page Number", ((s->details->caps & AST_FAX_TECH_RECEIVE) ? stats.pages_rx : stats.pages_tx) + 1);
 #else
-               ast_cli(fd, "%-22s : %d\n", "Page Number", stats.pages_transferred + 1);
+                       ast_cli(fd, "%-22s : %d\n", "Page Number", stats.pages_transferred + 1);
 #endif
-               ast_cli(fd, "%-22s : %s\n", "File Name", s->details->caps & AST_FAX_TECH_RECEIVE ? p->t30_state->rx_file : p->t30_state->tx_file);
+                       ast_cli(fd, "%-22s : %s\n", "File Name", s->details->caps & AST_FAX_TECH_RECEIVE ? p->t30_state->rx_file : p->t30_state->tx_file);
 
-               ast_cli(fd, "\nData Statistics:\n");
+                       ast_cli(fd, "\nData Statistics:\n");
 #if SPANDSP_RELEASE_DATE >= 20090220
-               ast_cli(fd, "%-22s : %d\n", "Tx Pages", stats.pages_tx);
-               ast_cli(fd, "%-22s : %d\n", "Rx Pages", stats.pages_rx);
+                       ast_cli(fd, "%-22s : %d\n", "Tx Pages", stats.pages_tx);
+                       ast_cli(fd, "%-22s : %d\n", "Rx Pages", stats.pages_rx);
 #else
-               ast_cli(fd, "%-22s : %d\n", "Tx Pages", (s->details->caps & AST_FAX_TECH_SEND) ? stats.pages_transferred : 0);
-               ast_cli(fd, "%-22s : %d\n", "Rx Pages", (s->details->caps & AST_FAX_TECH_RECEIVE) ? stats.pages_transferred : 0);
+                       ast_cli(fd, "%-22s : %d\n", "Tx Pages", (s->details->caps & AST_FAX_TECH_SEND) ? stats.pages_transferred : 0);
+                       ast_cli(fd, "%-22s : %d\n", "Rx Pages", (s->details->caps & AST_FAX_TECH_RECEIVE) ? stats.pages_transferred : 0);
 #endif
-               ast_cli(fd, "%-22s : %d\n", "Longest Bad Line Run", stats.longest_bad_row_run);
-               ast_cli(fd, "%-22s : %d\n", "Total Bad Lines", stats.bad_rows);
+                       ast_cli(fd, "%-22s : %d\n", "Longest Bad Line Run", stats.longest_bad_row_run);
+                       ast_cli(fd, "%-22s : %d\n", "Total Bad Lines", stats.bad_rows);
+               }
        }
        ao2_unlock(s);
        ast_cli(fd, "\n\n");