[Freeswitch-svn] [commit] r13082 - freeswitch/trunk/src/mod/applications/mod_t38gateway
FreeSWITCH SVN
coppice at freeswitch.org
Sun Apr 19 04:46:26 PDT 2009
Author: coppice
Date: Sun Apr 19 06:46:26 2009
New Revision: 13082
Log:
Introduction of the skeleton of a media bug implementing a T.38 gateway, so the
related infrastructure work can take place around it.
Added:
freeswitch/trunk/src/mod/applications/mod_t38gateway/
freeswitch/trunk/src/mod/applications/mod_t38gateway/Makefile
freeswitch/trunk/src/mod/applications/mod_t38gateway/mod_t38gateway.2008.vcproj
freeswitch/trunk/src/mod/applications/mod_t38gateway/mod_t38gateway.c
freeswitch/trunk/src/mod/applications/mod_t38gateway/udptl.c
freeswitch/trunk/src/mod/applications/mod_t38gateway/udptl.h
Added: freeswitch/trunk/src/mod/applications/mod_t38gateway/Makefile
==============================================================================
--- (empty file)
+++ freeswitch/trunk/src/mod/applications/mod_t38gateway/Makefile Sun Apr 19 06:46:26 2009
@@ -0,0 +1,6 @@
+BASE=../../../..
+
+LOCAL_SOURCES=udptl.c
+LOCAL_OBJS=udptl.o
+
+include $(BASE)/build/modmake.rules
Added: freeswitch/trunk/src/mod/applications/mod_t38gateway/mod_t38gateway.2008.vcproj
==============================================================================
--- (empty file)
+++ freeswitch/trunk/src/mod/applications/mod_t38gateway/mod_t38gateway.2008.vcproj Sun Apr 19 06:46:26 2009
@@ -0,0 +1,291 @@
+<?xml version="1.0" encoding="Windows-1252"?>
+<VisualStudioProject
+ ProjectType="Visual C++"
+ Version="9.00"
+ Name="mod_t38gateway"
+ ProjectGUID="{14E4A972-9CFB-436D-B0A5-4943F3F80D47}"
+ RootNamespace="mod_t38gateway"
+ Keyword="Win32Proj"
+ TargetFrameworkVersion="131072"
+ >
+ <Platforms>
+ <Platform
+ Name="Win32"
+ />
+ <Platform
+ Name="x64"
+ />
+ </Platforms>
+ <ToolFiles>
+ </ToolFiles>
+ <Configurations>
+ <Configuration
+ Name="Debug|Win32"
+ ConfigurationType="2"
+ InheritedPropertySheets="..\..\..\..\w32\module_debug.vsprops"
+ CharacterSet="2"
+ >
+ <Tool
+ Name="VCPreBuildEventTool"
+ />
+ <Tool
+ Name="VCCustomBuildTool"
+ />
+ <Tool
+ Name="VCXMLDataGeneratorTool"
+ />
+ <Tool
+ Name="VCWebServiceProxyGeneratorTool"
+ />
+ <Tool
+ Name="VCMIDLTool"
+ />
+ <Tool
+ Name="VCCLCompilerTool"
+ AdditionalIncludeDirectories=""$(InputDir)..\..\..\..\libs\spandsp\src\msvc";"$(InputDir)..\..\..\..\libs\spandsp\src";"$(InputDir)..\..\..\..\libs\tiff-3.8.2\libtiff""
+ UsePrecompiledHeader="0"
+ />
+ <Tool
+ Name="VCManagedResourceCompilerTool"
+ />
+ <Tool
+ Name="VCResourceCompilerTool"
+ />
+ <Tool
+ Name="VCPreLinkEventTool"
+ />
+ <Tool
+ Name="VCLinkerTool"
+ RandomizedBaseAddress="1"
+ DataExecutionPrevention="0"
+ />
+ <Tool
+ Name="VCALinkTool"
+ />
+ <Tool
+ Name="VCManifestTool"
+ />
+ <Tool
+ Name="VCXDCMakeTool"
+ />
+ <Tool
+ Name="VCBscMakeTool"
+ />
+ <Tool
+ Name="VCFxCopTool"
+ />
+ <Tool
+ Name="VCAppVerifierTool"
+ />
+ <Tool
+ Name="VCPostBuildEventTool"
+ />
+ </Configuration>
+ <Configuration
+ Name="Debug|x64"
+ ConfigurationType="2"
+ InheritedPropertySheets="..\..\..\..\w32\module_debug.vsprops"
+ CharacterSet="2"
+ >
+ <Tool
+ Name="VCPreBuildEventTool"
+ />
+ <Tool
+ Name="VCCustomBuildTool"
+ />
+ <Tool
+ Name="VCXMLDataGeneratorTool"
+ />
+ <Tool
+ Name="VCWebServiceProxyGeneratorTool"
+ />
+ <Tool
+ Name="VCMIDLTool"
+ TargetEnvironment="3"
+ />
+ <Tool
+ Name="VCCLCompilerTool"
+ AdditionalIncludeDirectories=""$(InputDir)..\..\..\..\libs\spandsp\src\msvc";"$(InputDir)..\..\..\..\libs\spandsp\src";"$(InputDir)..\..\..\..\libs\tiff-3.8.2\libtiff""
+ UsePrecompiledHeader="0"
+ />
+ <Tool
+ Name="VCManagedResourceCompilerTool"
+ />
+ <Tool
+ Name="VCResourceCompilerTool"
+ />
+ <Tool
+ Name="VCPreLinkEventTool"
+ />
+ <Tool
+ Name="VCLinkerTool"
+ OutputFile="$(SolutionDir)$(PlatformName)\$(ConfigurationName)/mod/$(ProjectName).dll"
+ RandomizedBaseAddress="1"
+ DataExecutionPrevention="0"
+ TargetMachine="17"
+ />
+ <Tool
+ Name="VCALinkTool"
+ />
+ <Tool
+ Name="VCManifestTool"
+ />
+ <Tool
+ Name="VCXDCMakeTool"
+ />
+ <Tool
+ Name="VCBscMakeTool"
+ />
+ <Tool
+ Name="VCFxCopTool"
+ />
+ <Tool
+ Name="VCAppVerifierTool"
+ />
+ <Tool
+ Name="VCPostBuildEventTool"
+ />
+ </Configuration>
+ <Configuration
+ Name="Release|Win32"
+ ConfigurationType="2"
+ InheritedPropertySheets="..\..\..\..\w32\module_release.vsprops"
+ CharacterSet="2"
+ >
+ <Tool
+ Name="VCPreBuildEventTool"
+ />
+ <Tool
+ Name="VCCustomBuildTool"
+ />
+ <Tool
+ Name="VCXMLDataGeneratorTool"
+ />
+ <Tool
+ Name="VCWebServiceProxyGeneratorTool"
+ />
+ <Tool
+ Name="VCMIDLTool"
+ />
+ <Tool
+ Name="VCCLCompilerTool"
+ AdditionalIncludeDirectories=""$(InputDir)..\..\..\..\libs\spandsp\src\msvc";"$(InputDir)..\..\..\..\libs\spandsp\src";"$(InputDir)..\..\..\..\libs\tiff-3.8.2\libtiff""
+ UsePrecompiledHeader="0"
+ />
+ <Tool
+ Name="VCManagedResourceCompilerTool"
+ />
+ <Tool
+ Name="VCResourceCompilerTool"
+ />
+ <Tool
+ Name="VCPreLinkEventTool"
+ />
+ <Tool
+ Name="VCLinkerTool"
+ RandomizedBaseAddress="1"
+ DataExecutionPrevention="0"
+ />
+ <Tool
+ Name="VCALinkTool"
+ />
+ <Tool
+ Name="VCManifestTool"
+ />
+ <Tool
+ Name="VCXDCMakeTool"
+ />
+ <Tool
+ Name="VCBscMakeTool"
+ />
+ <Tool
+ Name="VCFxCopTool"
+ />
+ <Tool
+ Name="VCAppVerifierTool"
+ />
+ <Tool
+ Name="VCPostBuildEventTool"
+ />
+ </Configuration>
+ <Configuration
+ Name="Release|x64"
+ ConfigurationType="2"
+ InheritedPropertySheets="..\..\..\..\w32\module_release.vsprops"
+ CharacterSet="2"
+ >
+ <Tool
+ Name="VCPreBuildEventTool"
+ />
+ <Tool
+ Name="VCCustomBuildTool"
+ />
+ <Tool
+ Name="VCXMLDataGeneratorTool"
+ />
+ <Tool
+ Name="VCWebServiceProxyGeneratorTool"
+ />
+ <Tool
+ Name="VCMIDLTool"
+ TargetEnvironment="3"
+ />
+ <Tool
+ Name="VCCLCompilerTool"
+ AdditionalIncludeDirectories=""$(InputDir)..\..\..\..\libs\spandsp\src\msvc";"$(InputDir)..\..\..\..\libs\spandsp\src";"$(InputDir)..\..\..\..\libs\tiff-3.8.2\libtiff""
+ UsePrecompiledHeader="0"
+ />
+ <Tool
+ Name="VCManagedResourceCompilerTool"
+ />
+ <Tool
+ Name="VCResourceCompilerTool"
+ />
+ <Tool
+ Name="VCPreLinkEventTool"
+ />
+ <Tool
+ Name="VCLinkerTool"
+ OutputFile="$(SolutionDir)$(PlatformName)\$(ConfigurationName)/mod/$(ProjectName).dll"
+ RandomizedBaseAddress="1"
+ DataExecutionPrevention="0"
+ TargetMachine="17"
+ />
+ <Tool
+ Name="VCALinkTool"
+ />
+ <Tool
+ Name="VCManifestTool"
+ />
+ <Tool
+ Name="VCXDCMakeTool"
+ />
+ <Tool
+ Name="VCBscMakeTool"
+ />
+ <Tool
+ Name="VCFxCopTool"
+ />
+ <Tool
+ Name="VCAppVerifierTool"
+ />
+ <Tool
+ Name="VCPostBuildEventTool"
+ />
+ </Configuration>
+ </Configurations>
+ <References>
+ </References>
+ <Files>
+ <File
+ RelativePath=".\mod_t38gateway.c"
+ >
+ </File>
+ <File
+ RelativePath=".\udptl.c"
+ >
+ </File>
+ </Files>
+ <Globals>
+ </Globals>
+</VisualStudioProject>
Added: freeswitch/trunk/src/mod/applications/mod_t38gateway/mod_t38gateway.c
==============================================================================
--- (empty file)
+++ freeswitch/trunk/src/mod/applications/mod_t38gateway/mod_t38gateway.c Sun Apr 19 06:46:26 2009
@@ -0,0 +1,347 @@
+/*
+ * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
+ * Copyright (C) 2009, Steve Underwood <steveu at coppice.org>
+ *
+ * Version: MPL 1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * Contributor(s):
+ *
+ * Steve Underwood <steveu at coppice.org>
+ *
+ * mod_t38gateway.c -- A T.38 gateway
+ *
+ * This module uses the T.38 gateway engine of spandsp to create a T.38 gateway suitable for
+ * V.17, V.29, and V.27ter FAX operation.
+ *
+ */
+
+#include <switch.h>
+
+#define SPANDSP_EXPOSE_INTERNAL_STRUCTURES
+#include <spandsp.h>
+#include <spandsp/version.h>
+
+#include "udptl.h"
+
+/*! Syntax of the API call. */
+#define T38GATEWAY_SYNTAX "<uuid> <command>"
+
+/*! Number of expected parameters in api call. */
+#define T38GATEWAY_PARAMS 2
+
+/*! FreeSWITCH CUSTOM event types. */
+#define T38GATEWAY_EVENT_CNG "t38gateway::cng"
+#define T38GATEWAY_EVENT_CED "t38gateway::ced"
+#define T38GATEWAY_EVENT_PAGE "t38gateway::page"
+
+/* Prototypes */
+SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_t38gateway_shutdown);
+SWITCH_STANDARD_API(t38gateway_api_main);
+
+SWITCH_MODULE_LOAD_FUNCTION(mod_t38gateway_load);
+SWITCH_MODULE_DEFINITION(mod_t38gateway, mod_t38gateway_load, NULL, NULL);
+SWITCH_STANDARD_APP(t38gateway_start_function);
+
+/*! Type that holds codec information. */
+typedef struct {
+ /*! The sampling rate of the audio stream. */
+ int rate;
+ /*! The number of channels. */
+ int channels;
+} t38gateway_codec_info_t;
+
+/*! Type that holds session information pertinent to the t38gateway module. */
+typedef struct {
+ /*! Internal FreeSWITCH session. */
+ switch_core_session_t *session;
+ /*! Codec information for the session. */
+ t38gateway_codec_info_t t38gateway_codec;
+ t38_gateway_state_t *t38;
+ t38_core_state_t *t38_core;
+ udptl_state_t *udptl;
+} t38gateway_session_info_t;
+
+static int tx_packet_handler(t38_core_state_t *s, void *user_data, const uint8_t *buf, int len, int count)
+{
+ t38gateway_session_info_t *t;
+
+ t = (t38gateway_session_info_t *) user_data;
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+static int rx_packet_handler(void *user_data, const uint8_t *buf, int len, int seq_no)
+{
+ t38gateway_session_info_t *t;
+
+ t = (t38gateway_session_info_t *) user_data;
+ t38_core_rx_ifp_packet(t->t38_core, buf, len, seq_no);
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! \brief The callback function that is called when new audio data becomes available
+ *
+ * @author Steve Underwood
+ * @param bug A reference to the media bug.
+ * @param user_data The session information for this call.
+ * @param type The switch callback type.
+ * @return The success or failure of the function.
+ */
+static switch_bool_t t38gateway_callback(switch_media_bug_t * bug, void *user_data, switch_abc_type_t type)
+{
+ t38gateway_session_info_t *t38gateway_info;
+ switch_codec_t *read_codec;
+ switch_frame_t *frame;
+ int16_t *amp;
+
+ t38gateway_info = (t38gateway_session_info_t *) user_data;
+ if (t38gateway_info == NULL) {
+ return SWITCH_FALSE;
+ }
+
+ switch (type) {
+ case SWITCH_ABC_TYPE_INIT:
+ read_codec = switch_core_session_get_read_codec(t38gateway_info->session);
+ t38gateway_info->t38gateway_codec.rate = read_codec->implementation->samples_per_second;
+ t38gateway_info->t38gateway_codec.channels = read_codec->implementation->number_of_channels;
+ break;
+ case SWITCH_ABC_TYPE_READ_PING:
+ case SWITCH_ABC_TYPE_CLOSE:
+ break;
+ case SWITCH_ABC_TYPE_READ:
+ frame = switch_core_media_bug_get_read_replace_frame(bug);
+ amp = (int16_t *) frame->data;
+ t38_gateway_rx(t38gateway_info->t38, amp, frame->samples);
+ break;
+ case SWITCH_ABC_TYPE_WRITE:
+ case SWITCH_ABC_TYPE_READ_REPLACE:
+ case SWITCH_ABC_TYPE_WRITE_REPLACE:
+ break;
+ }
+
+ return SWITCH_TRUE;
+}
+
+/*! \brief FreeSWITCH module loading function
+ *
+ * @author Steve Underwood
+ * @return Load success or failure.
+ */
+SWITCH_MODULE_LOAD_FUNCTION(mod_t38gateway_load)
+{
+ switch_application_interface_t *app_interface;
+ switch_api_interface_t *api_interface;
+ /* connect my internal structure to the blank pointer passed to me */
+ *module_interface = switch_loadable_module_create_module_interface(pool, modname);
+
+ switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "T.38 gateway enabled\n");
+
+ SWITCH_ADD_APP(app_interface, "t38gateway", "T.38 gateway", "T.38 gateway", t38gateway_start_function, "[start] [stop]", SAF_NONE);
+
+ SWITCH_ADD_API(api_interface, "t38gateway", "T.38 gateway", t38gateway_api_main, T38GATEWAY_SYNTAX);
+
+ /* indicate that the module should continue to be loaded */
+ return SWITCH_STATUS_SUCCESS;
+}
+
+/*! \brief FreeSWITCH application handler function.
+ * This handles calls made from applications such as LUA and the dialplan
+ *
+ * @author Steve Underwood
+ * @return Success or failure of the function.
+ */
+SWITCH_STANDARD_APP(t38gateway_start_function)
+{
+ switch_media_bug_t *bug;
+ switch_status_t status;
+ switch_channel_t *channel;
+ t38gateway_session_info_t *t38gateway_info;
+
+ if (session == NULL)
+ return;
+
+ channel = switch_core_session_get_channel(session);
+
+ /* Is this channel already set? */
+ bug = (switch_media_bug_t *) switch_channel_get_private(channel, "_t38gateway_");
+ /* If yes */
+ if (bug != NULL) {
+ /* If we have a stop remove audio bug */
+ if (strcasecmp(data, "stop") == 0) {
+ switch_channel_set_private(channel, "_t38gateway_", NULL);
+ switch_core_media_bug_remove(session, &bug);
+ return;
+ }
+
+ /* We have already started */
+ switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Cannot run 2 at once on the same channel!\n");
+
+ return;
+ }
+
+ t38gateway_info = (t38gateway_session_info_t *) switch_core_session_alloc(session, sizeof(t38gateway_session_info_t));
+
+ t38gateway_info->session = session;
+ t38gateway_info->t38 = t38_gateway_init(NULL, tx_packet_handler, (void *) t38gateway_info);
+ t38gateway_info->t38_core = t38_gateway_get_t38_core_state(t38gateway_info->t38);
+ t38gateway_info->udptl = udptl_init(NULL, UDPTL_ERROR_CORRECTION_REDUNDANCY, 3, 3, rx_packet_handler, (void *) t38gateway_info);
+
+ status = switch_core_media_bug_add(session, t38gateway_callback, t38gateway_info, 0, SMBF_READ_STREAM, &bug);
+
+ if (status != SWITCH_STATUS_SUCCESS) {
+ switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Failure hooking to stream\n");
+ return;
+ }
+
+ switch_channel_set_private(channel, "_t38gateway_", bug);
+}
+
+/*! \brief Called when the module shuts down
+ *
+ * @author Steve Underwood
+ * @return The success or failure of the function.
+ */
+SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_t38gateway_shutdown)
+{
+ switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "T.38 gateway disabled\n");
+
+ return SWITCH_STATUS_SUCCESS;
+}
+
+/*! \brief FreeSWITCH API handler function.
+ * This function handles API calls such as the ones from mod_event_socket and in some cases
+ * scripts such as LUA scripts.
+ *
+ * @author Steve Underwood
+ * @return The success or failure of the function.
+ */
+SWITCH_STANDARD_API(t38gateway_api_main)
+{
+ switch_core_session_t *t38gateway_session;
+ switch_media_bug_t *bug;
+ t38gateway_session_info_t *t38gateway_info;
+ switch_channel_t *channel;
+ switch_status_t status;
+ int argc;
+ char *argv[T38GATEWAY_PARAMS];
+ char *ccmd;
+ char *uuid;
+ char *command;
+
+ /* No command? Display usage */
+ if (cmd == NULL) {
+ stream->write_function(stream, "-USAGE: %s\n", T38GATEWAY_SYNTAX);
+ return SWITCH_STATUS_SUCCESS;
+ }
+
+ /* Duplicated contents of original string */
+ ccmd = strdup(cmd);
+ /* Separate the arguments */
+ argc = switch_separate_string(ccmd, ' ', argv, T38GATEWAY_PARAMS);
+
+ /* If we don't have the expected number of parameters
+ * display usage */
+ if (argc != T38GATEWAY_PARAMS) {
+ stream->write_function(stream, "-USAGE: %s\n", T38GATEWAY_SYNTAX);
+ switch_safe_free(ccmd);
+ return SWITCH_STATUS_SUCCESS;
+ }
+
+ uuid = argv[0];
+ command = argv[1];
+
+ /* using uuid locate a reference to the FreeSWITCH session */
+ t38gateway_session = switch_core_session_locate(uuid);
+
+ /* If the session was not found exit */
+ if (t38gateway_session == NULL) {
+ switch_safe_free(ccmd);
+ stream->write_function(stream, "-USAGE: %s\n", T38GATEWAY_SYNTAX);
+ return SWITCH_STATUS_FALSE;
+ }
+
+ /* Get current channel of the session to tag the session
+ * This indicates that our module is present */
+ channel = switch_core_session_get_channel(t38gateway_session);
+
+ /* Is this channel already set? */
+ bug = (switch_media_bug_t *) switch_channel_get_private(channel, "_t38gateway_");
+ /* If yes */
+ if (bug != NULL) {
+ /* If we have a stop remove audio bug */
+ if (strcasecmp(command, "stop") == 0) {
+ switch_channel_set_private(channel, "_t38gateway_", NULL);
+ switch_core_media_bug_remove(t38gateway_session, &bug);
+ switch_safe_free(ccmd);
+ stream->write_function(stream, "+OK\n");
+ return SWITCH_STATUS_SUCCESS;
+ }
+
+ /* We have already started */
+ switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Cannot run 2 at once on the same channel!\n");
+
+ switch_safe_free(ccmd);
+ return SWITCH_STATUS_FALSE;
+ }
+
+ /* If we don't see the expected start exit */
+ if (strcasecmp(command, "start") != 0) {
+ switch_safe_free(ccmd);
+ stream->write_function(stream, "-USAGE: %s\n", T38GATEWAY_SYNTAX);
+ return SWITCH_STATUS_FALSE;
+ }
+
+ /* Allocate memory attached to this FreeSWITCH session for
+ * use in the callback routine and to store state information */
+ t38gateway_info = (t38gateway_session_info_t *) switch_core_session_alloc(t38gateway_session, sizeof(t38gateway_session_info_t));
+
+ /* Set initial values and states */
+ t38gateway_info->session = t38gateway_session;
+ t38gateway_info->t38 = t38_gateway_init(NULL, tx_packet_handler, (void *) t38gateway_info);
+ t38gateway_info->t38_core = t38_gateway_get_t38_core_state(t38gateway_info->t38);
+ t38gateway_info->udptl = udptl_init(NULL, UDPTL_ERROR_CORRECTION_REDUNDANCY, 3, 3, rx_packet_handler, (void *) t38gateway_info);
+
+ /* Add a media bug that allows me to intercept the
+ * reading leg of the audio stream */
+ status = switch_core_media_bug_add(t38gateway_session, t38gateway_callback, t38gateway_info, 0, SMBF_READ_STREAM, &bug);
+
+ /* If adding a media bug fails exit */
+ if (status != SWITCH_STATUS_SUCCESS) {
+ switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Failure hooking to stream\n");
+
+ switch_safe_free(ccmd);
+ return SWITCH_STATUS_FALSE;
+ }
+
+ /* Set the t38gateway tag to detect an existing t38gateway media bug */
+ switch_channel_set_private(channel, "_t38gateway_", bug);
+
+ /* Everything went according to plan! Notify the user */
+ stream->write_function(stream, "+OK\n");
+
+ switch_safe_free(ccmd);
+ return SWITCH_STATUS_SUCCESS;
+}
+
+
+/* For Emacs:
+ * Local Variables:
+ * mode:c
+ * indent-tabs-mode:t
+ * tab-width:4
+ * c-basic-offset:4
+ * End:
+ * For VIM:
+ * vim:set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:
+ */
Added: freeswitch/trunk/src/mod/applications/mod_t38gateway/udptl.c
==============================================================================
--- (empty file)
+++ freeswitch/trunk/src/mod/applications/mod_t38gateway/udptl.c Sun Apr 19 06:46:26 2009
@@ -0,0 +1,596 @@
+//#define UDPTL_DEBUG
+/*
+ * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
+ * Copyright (C) 2009, Steve Underwood <steveu at coppice.org>
+ *
+ * Version: MPL 1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * Contributor(s):
+ *
+ * Steve Underwood <steveu at coppice.org>
+ *
+ * udptl.c -- UDPTL handling for T.38
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <inttypes.h>
+#include <memory.h>
+
+#include "udptl.h"
+
+#define FALSE 0
+#define TRUE (!FALSE)
+
+static int decode_length(const uint8_t *buf, int limit, int *len, int *pvalue)
+{
+ if (*len >= limit)
+ return -1;
+ if ((buf[*len] & 0x80) == 0)
+ {
+ *pvalue = buf[(*len)++];
+ return 0;
+ }
+ if ((buf[*len] & 0x40) == 0)
+ {
+ if (*len >= limit - 1)
+ return -1;
+ *pvalue = (buf[(*len)++] & 0x3F) << 8;
+ *pvalue |= buf[(*len)++];
+ return 0;
+ }
+ *pvalue = (buf[(*len)++] & 0x3F) << 14;
+ /* Indicate we have a fragment */
+ return 1;
+}
+/*- End of function --------------------------------------------------------*/
+
+static int decode_open_type(const uint8_t *buf, int limit, int *len, const uint8_t **p_object, int *p_num_octets)
+{
+ int octet_cnt;
+ int octet_idx;
+ int stat;
+ int i;
+ const uint8_t **pbuf;
+
+ for (octet_idx = 0, *p_num_octets = 0; ; octet_idx += octet_cnt)
+ {
+ if ((stat = decode_length(buf, limit, len, &octet_cnt)) < 0)
+ return -1;
+ if (octet_cnt > 0)
+ {
+ *p_num_octets += octet_cnt;
+
+ pbuf = &p_object[octet_idx];
+ i = 0;
+ /* Make sure the buffer contains at least the number of bits requested */
+ if ((*len + octet_cnt) > limit)
+ return -1;
+
+ *pbuf = &buf[*len];
+ *len += octet_cnt;
+ }
+ if (stat == 0)
+ break;
+ }
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+static int encode_length(uint8_t *buf, int *len, int value)
+{
+ int multiplier;
+
+ if (value < 0x80)
+ {
+ /* 1 octet */
+ buf[(*len)++] = value;
+ return value;
+ }
+ if (value < 0x4000)
+ {
+ /* 2 octets */
+ /* Set the first bit of the first octet */
+ buf[(*len)++] = ((0x8000 | value) >> 8) & 0xFF;
+ buf[(*len)++] = value & 0xFF;
+ return value;
+ }
+ /* Fragmentation */
+ multiplier = (value < 0x10000) ? (value >> 14) : 4;
+ /* Set the first 2 bits of the octet */
+ buf[(*len)++] = 0xC0 | multiplier;
+ return multiplier << 14;
+}
+/*- End of function --------------------------------------------------------*/
+
+static int encode_open_type(uint8_t *buf, int *len, const uint8_t *data, int num_octets)
+{
+ int enclen;
+ int octet_idx;
+ uint8_t zero_byte;
+
+ /* If open type is of zero length, add a single zero byte (10.1) */
+ if (num_octets == 0)
+ {
+ zero_byte = 0;
+ data = &zero_byte;
+ num_octets = 1;
+ }
+ /* Encode the open type */
+ for (octet_idx = 0; ; num_octets -= enclen, octet_idx += enclen)
+ {
+ if ((enclen = encode_length(buf, len, num_octets)) < 0)
+ return -1;
+ if (enclen > 0)
+ {
+ memcpy(&buf[*len], &data[octet_idx], enclen);
+ *len += enclen;
+ }
+ if (enclen >= num_octets)
+ break;
+ }
+
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_rx_packet(udptl_state_t *s, const uint8_t buf[], int len)
+{
+ int stat;
+ int stat2;
+ int i;
+ int j;
+ int k;
+ int l;
+ int m;
+ int x;
+ int limit;
+ int which;
+ int ptr;
+ int count;
+ int total_count;
+ int seq_no;
+ const uint8_t *msg;
+ const uint8_t *data;
+ int msg_len;
+ int repaired[16];
+ const uint8_t *bufs[16];
+ int lengths[16];
+ int span;
+ int entries;
+
+ ptr = 0;
+ /* Decode seq_number */
+ if (ptr + 2 > len)
+ return -1;
+ seq_no = (buf[0] << 8) | buf[1];
+ ptr += 2;
+ /* Break out the primary packet */
+ if ((stat = decode_open_type(buf, len, &ptr, &msg, &msg_len)) != 0)
+ return -1;
+ /* Decode error_recovery */
+ if (ptr + 1 > len)
+ return -1;
+ /* Our buffers cannot tolerate overlength packets */
+ if (msg_len > LOCAL_FAX_MAX_DATAGRAM)
+ return -1;
+ /* Update any missed slots in the buffer */
+ for (i = s->rx_seq_no; seq_no > i; i++)
+ {
+ x = i & UDPTL_BUF_MASK;
+ s->rx[x].buf_len = -1;
+ s->rx[x].fec_len[0] = 0;
+ s->rx[x].fec_span = 0;
+ s->rx[x].fec_entries = 0;
+ }
+ /* Save the new packet. Pure redundancy mode won't use this, but some systems will switch
+ into FEC mode after sending some redundant packets. */
+ x = seq_no & UDPTL_BUF_MASK;
+ memcpy(s->rx[x].buf, msg, msg_len);
+ s->rx[x].buf_len = msg_len;
+ s->rx[x].fec_len[0] = 0;
+ s->rx[x].fec_span = 0;
+ s->rx[x].fec_entries = 0;
+ if ((buf[ptr++] & 0x80) == 0)
+ {
+ /* Secondary packet mode for error recovery */
+ /* We might have the packet we want, but we need to check through
+ the redundant stuff, and verify the integrity of the UDPTL.
+ This greatly reduces our chances of accepting garbage. */
+ total_count = 0;
+ do
+ {
+ if ((stat2 = decode_length(buf, len, &ptr, &count)) < 0)
+ return -1;
+ for (i = 0; i < count; i++)
+ {
+ if ((stat = decode_open_type(buf, len, &ptr, &bufs[total_count + i], &lengths[total_count + i])) != 0)
+ return -1;
+ }
+ total_count += count;
+ }
+ while (stat2 > 0);
+ /* We should now be exactly at the end of the packet. If not, this is a fault. */
+ if (ptr != len)
+ return -1;
+ if (seq_no > s->rx_seq_no)
+ {
+ /* We received a later packet than we expected, so we need to check if we can fill in the gap from the
+ secondary packets. */
+ /* Step through in reverse order, so we go oldest to newest */
+ for (i = total_count; i > 0; i--)
+ {
+ if (seq_no - i >= s->rx_seq_no)
+ {
+ /* This one wasn't seen before */
+ /* Decode the secondary packet */
+#if defined(UDPTL_DEBUG)
+ fprintf(stderr, "Secondary %d, len %d\n", seq_no - i, lengths[i - 1]);
+#endif
+ /* Save the new packet. Redundancy mode won't use this, but some systems will switch into
+ FEC mode after sending some redundant packets, and this may then be important. */
+ x = (seq_no - i) & UDPTL_BUF_MASK;
+ memcpy(s->rx[x].buf, bufs[i - 1], lengths[i - 1]);
+ s->rx[x].buf_len = lengths[i - 1];
+ s->rx[x].fec_len[0] = 0;
+ s->rx[x].fec_span = 0;
+ s->rx[x].fec_entries = 0;
+ if (s->rx_packet_handler(s->user_data, bufs[i - 1], lengths[i - 1], seq_no - i) < 0)
+ fprintf(stderr, "Bad IFP\n");
+ }
+ }
+ }
+ }
+ else
+ {
+ /* FEC mode for error recovery */
+
+ /* Decode the FEC packets */
+ /* The span is defined as an unconstrained integer, but will never be more
+ than a small value. */
+ if (ptr + 2 > len)
+ return -1;
+ if (buf[ptr++] != 1)
+ return -1;
+ span = buf[ptr++];
+
+ x = seq_no & UDPTL_BUF_MASK;
+
+ s->rx[x].fec_span = span;
+
+ memset(repaired, 0, sizeof(repaired));
+ repaired[x] = TRUE;
+
+ /* The number of entries is defined as a length, but will only ever be a small
+ value. Treat it as such. */
+ if (ptr + 1 > len)
+ return -1;
+ entries = buf[ptr++];
+ s->rx[x].fec_entries = entries;
+
+ /* Decode the elements */
+ for (i = 0; i < entries; i++)
+ {
+ if ((stat = decode_open_type(buf, len, &ptr, &data, &s->rx[x].fec_len[i])) != 0)
+ return -1;
+ if (s->rx[x].fec_len[i] > LOCAL_FAX_MAX_DATAGRAM)
+ return -1;
+
+ /* Save the new FEC data */
+ memcpy(s->rx[x].fec[i], data, s->rx[x].fec_len[i]);
+#if 0
+ fprintf(stderr, "FEC: ");
+ for (j = 0; j < s->rx[x].fec_len[i]; j++)
+ fprintf(stderr, "%02X ", data[j]);
+ fprintf(stderr, "\n");
+#endif
+ }
+ /* We should now be exactly at the end of the packet. If not, this is a fault. */
+ if (ptr != len)
+ return -1;
+ /* See if we can reconstruct anything which is missing */
+ /* TODO: this does not comprehensively hunt back and repair everything that is possible */
+ for (l = x; l != ((x - (16 - span*entries)) & UDPTL_BUF_MASK); l = (l - 1) & UDPTL_BUF_MASK)
+ {
+ if (s->rx[l].fec_len[0] <= 0)
+ continue;
+ for (m = 0; m < s->rx[l].fec_entries; m++)
+ {
+ limit = (l + m) & UDPTL_BUF_MASK;
+ for (which = -1, k = (limit - s->rx[l].fec_span*s->rx[l].fec_entries) & UDPTL_BUF_MASK; k != limit; k = (k + s->rx[l].fec_entries) & UDPTL_BUF_MASK)
+ {
+ if (s->rx[k].buf_len <= 0)
+ which = (which == -1) ? k : -2;
+ }
+ if (which >= 0)
+ {
+ /* Repairable */
+ for (j = 0; j < s->rx[l].fec_len[m]; j++)
+ {
+ s->rx[which].buf[j] = s->rx[l].fec[m][j];
+ for (k = (limit - s->rx[l].fec_span*s->rx[l].fec_entries) & UDPTL_BUF_MASK; k != limit; k = (k + s->rx[l].fec_entries) & UDPTL_BUF_MASK)
+ s->rx[which].buf[j] ^= (s->rx[k].buf_len > j) ? s->rx[k].buf[j] : 0;
+ }
+ s->rx[which].buf_len = s->rx[l].fec_len[m];
+ repaired[which] = TRUE;
+ }
+ }
+ }
+ /* Now play any new packets forwards in time */
+ for (l = (x + 1) & UDPTL_BUF_MASK, j = seq_no - UDPTL_BUF_MASK; l != x; l = (l + 1) & UDPTL_BUF_MASK, j++)
+ {
+ if (repaired[l])
+ {
+#if defined(UDPTL_DEBUG)
+ fprintf(stderr, "Fixed packet %d, len %d\n", j, l);
+#endif
+ if (s->rx_packet_handler(s->user_data, s->rx[l].buf, s->rx[l].buf_len, j) < 0)
+ fprintf(stderr, "Bad IFP\n");
+ }
+ }
+ }
+ /* If packets are received out of sequence, we may have already processed this packet from the error
+ recovery information in a packet already received. */
+ if (seq_no >= s->rx_seq_no)
+ {
+ /* Decode the primary packet */
+#if defined(UDPTL_DEBUG)
+ fprintf(stderr, "Primary packet %d, len %d\n", seq_no, msg_len);
+#endif
+ if (s->rx_packet_handler(s->user_data, msg, msg_len, seq_no) < 0)
+ fprintf(stderr, "Bad IFP\n");
+ }
+
+ s->rx_seq_no = (seq_no + 1) & 0xFFFF;
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_build_packet(udptl_state_t *s, uint8_t buf[], const uint8_t msg[], int msg_len)
+{
+ uint8_t fec[LOCAL_FAX_MAX_DATAGRAM];
+ int i;
+ int j;
+ int seq;
+ int entry;
+ int entries;
+ int span;
+ int m;
+ int len;
+ int limit;
+ int high_tide;
+
+ /* UDPTL cannot cope with zero length messages, and our buffering for redundancy limits their
+ maximum length. */
+ if (msg_len < 1 || msg_len > LOCAL_FAX_MAX_DATAGRAM)
+ return -1;
+ seq = s->tx_seq_no & 0xFFFF;
+
+ /* Map the sequence number to an entry in the circular buffer */
+ entry = seq & UDPTL_BUF_MASK;
+
+ /* We save the message in a circular buffer, for generating FEC or
+ redundancy sets later on. */
+ s->tx[entry].buf_len = msg_len;
+ memcpy(s->tx[entry].buf, msg, msg_len);
+
+ /* Build the UDPTL packet */
+
+ len = 0;
+ /* Encode the sequence number */
+ buf[len++] = (seq >> 8) & 0xFF;
+ buf[len++] = seq & 0xFF;
+
+ /* Encode the primary packet */
+ if (encode_open_type(buf, &len, msg, msg_len) < 0)
+ return -1;
+
+ /* Encode the appropriate type of error recovery information */
+ switch (s->error_correction_scheme)
+ {
+ case UDPTL_ERROR_CORRECTION_NONE:
+ /* Encode the error recovery type */
+ buf[len++] = 0x00;
+ /* The number of entries will always be zero, so it is pointless allowing
+ for the fragmented case here. */
+ if (encode_length(buf, &len, 0) < 0)
+ return -1;
+ break;
+ case UDPTL_ERROR_CORRECTION_REDUNDANCY:
+ /* Encode the error recovery type */
+ buf[len++] = 0x00;
+ if (s->tx_seq_no > s->error_correction_entries)
+ entries = s->error_correction_entries;
+ else
+ entries = s->tx_seq_no;
+ /* The number of entries will always be small, so it is pointless allowing
+ for the fragmented case here. */
+ if (encode_length(buf, &len, entries) < 0)
+ return -1;
+ /* Encode the elements */
+ for (i = 0; i < entries; i++)
+ {
+ j = (entry - i - 1) & UDPTL_BUF_MASK;
+ if (encode_open_type(buf, &len, s->tx[j].buf, s->tx[j].buf_len) < 0)
+ return -1;
+ }
+ break;
+ case UDPTL_ERROR_CORRECTION_FEC:
+ span = s->error_correction_span;
+ entries = s->error_correction_entries;
+ if (seq < s->error_correction_span*s->error_correction_entries)
+ {
+ /* In the initial stages, wind up the FEC smoothly */
+ entries = seq/s->error_correction_span;
+ if (seq < s->error_correction_span)
+ span = 0;
+ }
+ /* Encode the error recovery type */
+ buf[len++] = 0x80;
+ /* Span is defined as an inconstrained integer, which it dumb. It will only
+ ever be a small value. Treat it as such. */
+ buf[len++] = 1;
+ buf[len++] = span;
+ /* The number of entries is defined as a length, but will only ever be a small
+ value. Treat it as such. */
+ buf[len++] = entries;
+ for (m = 0; m < entries; m++)
+ {
+ /* Make an XOR'ed entry the maximum length */
+ limit = (entry + m) & UDPTL_BUF_MASK;
+ high_tide = 0;
+ for (i = (limit - span*entries) & UDPTL_BUF_MASK; i != limit; i = (i + entries) & UDPTL_BUF_MASK)
+ {
+ if (high_tide < s->tx[i].buf_len)
+ {
+ for (j = 0; j < high_tide; j++)
+ fec[j] ^= s->tx[i].buf[j];
+ for ( ; j < s->tx[i].buf_len; j++)
+ fec[j] = s->tx[i].buf[j];
+ high_tide = s->tx[i].buf_len;
+ }
+ else
+ {
+ for (j = 0; j < s->tx[i].buf_len; j++)
+ fec[j] ^= s->tx[i].buf[j];
+ }
+ }
+ if (encode_open_type(buf, &len, fec, high_tide) < 0)
+ return -1;
+ }
+ break;
+ }
+
+ if (s->verbose)
+ fprintf(stderr, "\n");
+ s->tx_seq_no++;
+ return len;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_set_error_correction(udptl_state_t *s,
+ int ec_scheme,
+ int span,
+ int entries)
+{
+ switch (ec_scheme)
+ {
+ case UDPTL_ERROR_CORRECTION_FEC:
+ case UDPTL_ERROR_CORRECTION_REDUNDANCY:
+ case UDPTL_ERROR_CORRECTION_NONE:
+ s->error_correction_scheme = ec_scheme;
+ break;
+ case -1:
+ /* Just don't change the scheme */
+ break;
+ default:
+ return -1;
+ }
+ if (span >= 0)
+ s->error_correction_span = span;
+ if (entries >= 0)
+ s->error_correction_entries = entries;
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_get_error_correction(udptl_state_t *s,
+ int *ec_scheme,
+ int *span,
+ int *entries)
+{
+ if (ec_scheme)
+ *ec_scheme = s->error_correction_scheme;
+ if (span)
+ *span = s->error_correction_span;
+ if (entries)
+ *entries = s->error_correction_entries;
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_set_local_max_datagram(udptl_state_t *s, int max_datagram)
+{
+ s->local_max_datagram_size = max_datagram;
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_get_local_max_datagram(udptl_state_t *s)
+{
+ return s->local_max_datagram_size;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_set_far_max_datagram(udptl_state_t *s, int max_datagram)
+{
+ s->far_max_datagram_size = max_datagram;
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_get_far_max_datagram(udptl_state_t *s)
+{
+ return s->far_max_datagram_size;
+}
+/*- End of function --------------------------------------------------------*/
+
+udptl_state_t *udptl_init(udptl_state_t *s,
+ int ec_scheme,
+ int span,
+ int entries,
+ udptl_rx_packet_handler_t rx_packet_handler,
+ void *user_data)
+{
+ int i;
+
+ if (rx_packet_handler == NULL)
+ return NULL;
+
+ if (s == NULL)
+ {
+ if ((s = (udptl_state_t *) malloc(sizeof(*s))) == NULL)
+ return NULL;
+ }
+ memset(s, 0, sizeof(*s));
+
+ s->error_correction_scheme = ec_scheme;
+ s->error_correction_span = span;
+ s->error_correction_entries = entries;
+
+ s->far_max_datagram_size = LOCAL_FAX_MAX_DATAGRAM;
+ s->local_max_datagram_size = LOCAL_FAX_MAX_DATAGRAM;
+
+ memset(&s->rx, 0, sizeof(s->rx));
+ memset(&s->tx, 0, sizeof(s->tx));
+ for (i = 0; i <= UDPTL_BUF_MASK; i++)
+ {
+ s->rx[i].buf_len = -1;
+ s->tx[i].buf_len = -1;
+ }
+
+ s->rx_packet_handler = rx_packet_handler;
+ s->user_data = user_data;
+
+ return s;
+}
+/*- End of function --------------------------------------------------------*/
+
+int udptl_release(udptl_state_t *s)
+{
+ return 0;
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/
Added: freeswitch/trunk/src/mod/applications/mod_t38gateway/udptl.h
==============================================================================
--- (empty file)
+++ freeswitch/trunk/src/mod/applications/mod_t38gateway/udptl.h Sun Apr 19 06:46:26 2009
@@ -0,0 +1,170 @@
+/*
+ * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
+ * Copyright (C) 2009, Steve Underwood <steveu at coppice.org>
+ *
+ * Version: MPL 1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * Contributor(s):
+ *
+ * Steve Underwood <steveu at coppice.org>
+ *
+ * udptl.h -- UDPTL handling for T.38
+ *
+ */
+
+#if !defined(_UDPTL_H_)
+#define _UDPTL_H_
+
+#define LOCAL_FAX_MAX_DATAGRAM 400
+#define LOCAL_FAX_MAX_FEC_PACKETS 5
+
+#define UDPTL_BUF_MASK 15
+
+typedef int (udptl_rx_packet_handler_t)(void *user_data, const uint8_t msg[], int len, int seq_no);
+
+typedef struct
+{
+ int buf_len;
+ uint8_t buf[LOCAL_FAX_MAX_DATAGRAM];
+} udptl_fec_tx_buffer_t;
+
+typedef struct
+{
+ int buf_len;
+ uint8_t buf[LOCAL_FAX_MAX_DATAGRAM];
+ int fec_len[LOCAL_FAX_MAX_FEC_PACKETS];
+ uint8_t fec[LOCAL_FAX_MAX_FEC_PACKETS][LOCAL_FAX_MAX_DATAGRAM];
+ int fec_span;
+ int fec_entries;
+} udptl_fec_rx_buffer_t;
+
+struct udptl_state_s
+{
+ udptl_rx_packet_handler_t *rx_packet_handler;
+ void *user_data;
+
+ /*! This option indicates the error correction scheme used in transmitted UDPTL
+ packets. */
+ int error_correction_scheme;
+
+ /*! This option indicates the number of error correction entries transmitted in
+ UDPTL packets. */
+ int error_correction_entries;
+
+ /*! This option indicates the span of the error correction entries in transmitted
+ UDPTL packets (FEC only). */
+ int error_correction_span;
+
+ /*! This option indicates the maximum size of a datagram that can be accepted by
+ the remote device. */
+ int far_max_datagram_size;
+
+ /*! This option indicates the maximum size of a datagram that we are prepared to
+ accept. */
+ int local_max_datagram_size;
+
+ int verbose;
+
+ int tx_seq_no;
+ int rx_seq_no;
+ int rx_expected_seq_no;
+
+ udptl_fec_tx_buffer_t tx[UDPTL_BUF_MASK + 1];
+ udptl_fec_rx_buffer_t rx[UDPTL_BUF_MASK + 1];
+};
+
+enum
+{
+ UDPTL_ERROR_CORRECTION_NONE,
+ UDPTL_ERROR_CORRECTION_FEC,
+ UDPTL_ERROR_CORRECTION_REDUNDANCY
+};
+
+typedef struct udptl_state_s udptl_state_t;
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/*! \brief Process an arriving UDPTL packet.
+ \param s The UDPTL context.
+ \param buf The UDPTL packet buffer.
+ \param len The length of the packet.
+ \return 0 for OK. */
+int udptl_rx_packet(udptl_state_t *s, const uint8_t buf[], int len);
+
+/*! \brief Construct a UDPTL packet, ready for transmission.
+ \param s The UDPTL context.
+ \param buf The UDPTL packet buffer.
+ \param msg The primary packet.
+ \param len The length of the primary packet.
+ \return The length of the constructed UDPTL packet. */
+int udptl_build_packet(udptl_state_t *s, uint8_t buf[], const uint8_t msg[], int msg_len);
+
+/*! \brief Change the error correction settings of a UDPTL context.
+ \param s The UDPTL context.
+ \param ec_scheme One of the optional error correction schemes.
+ \param span The packet span over which error correction should be applied.
+ \param entries The number of error correction entries to include in packets.
+ \return 0 for OK. */
+int udptl_set_error_correction(udptl_state_t *s,
+ int ec_scheme,
+ int span,
+ int entries);
+
+/*! \brief Check the error correction settings of a UDPTL context.
+ \param s The UDPTL context.
+ \param ec_scheme One of the optional error correction schemes.
+ \param span The packet span over which error correction is being applied.
+ \param entries The number of error correction being included in packets.
+ \return 0 for OK. */
+int udptl_get_error_correction(udptl_state_t *s,
+ int *ec_scheme,
+ int *span,
+ int *entries);
+
+int udptl_set_local_max_datagram(udptl_state_t *s, int max_datagram);
+
+int udptl_get_local_max_datagram(udptl_state_t *s);
+
+int udptl_set_far_max_datagram(udptl_state_t *s, int max_datagram);
+
+int udptl_get_far_max_datagram(udptl_state_t *s);
+
+/*! \brief Initialise a UDPTL context.
+ \param s The UDPTL context.
+ \param ec_scheme One of the optional error correction schemes.
+ \param span The packet span over which error correction should be applied.
+ \param entries The number of error correction entries to include in packets.
+ \param rx_packet_handler The callback function, used to report arriving IFP packets.
+ \param user_data An opaque pointer supplied to rx_packet_handler.
+ \return A pointer to the UDPTL context, or NULL if there was a problem. */
+udptl_state_t *udptl_init(udptl_state_t *s,
+ int ec_scheme,
+ int span,
+ int entries,
+ udptl_rx_packet_handler_t rx_packet_handler,
+ void *user_data);
+
+/*! \brief Release a UDPTL context.
+ \param s The UDPTL context.
+ \return 0 for OK. */
+int udptl_release(udptl_state_t *s);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/
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