Diff: frame_codec.c

Revision:

0:6ae2f7bca550

Child:

5:ae49385aff34

diff -r 000000000000 -r 6ae2f7bca550 frame_codec.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/frame_codec.c	Fri Apr 08 12:01:10 2016 -0700
@@ -0,0 +1,630 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+#include <stdlib.h>
+#ifdef _CRTDBG_MAP_ALLOC
+#include <crtdbg.h>
+#endif
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include "azure_c_shared_utility/xlogging.h"
+#include "azure_c_shared_utility/xio.h"
+#include "azure_c_shared_utility/list.h"
+#include "azure_uamqp_c/frame_codec.h"
+#include "azure_uamqp_c/amqpvalue.h"
+#include "azure_uamqp_c/amqpalloc.h"
+
+#define FRAME_HEADER_SIZE 8
+#define MAX_TYPE_SPECIFIC_SIZE	((255 * 4) - 6)
+
+typedef enum RECEIVE_FRAME_STATE_TAG
+{
+	RECEIVE_FRAME_STATE_FRAME_SIZE,
+	RECEIVE_FRAME_STATE_DOFF,
+	RECEIVE_FRAME_STATE_FRAME_TYPE,
+	RECEIVE_FRAME_STATE_TYPE_SPECIFIC,
+	RECEIVE_FRAME_STATE_FRAME_BODY,
+	RECEIVE_FRAME_STATE_ERROR
+} RECEIVE_FRAME_STATE;
+
+typedef enum ENCODE_FRAME_STATE_TAG
+{
+	ENCODE_FRAME_STATE_IDLE,
+	ENCODE_FRAME_STATE_ERROR
+} ENCODE_FRAME_STATE;
+
+typedef struct SUBSCRIPTION_TAG
+{
+	uint8_t frame_type;
+	ON_FRAME_RECEIVED on_frame_received;
+	void* callback_context;
+} SUBSCRIPTION;
+
+typedef struct FRAME_CODEC_INSTANCE_TAG
+{
+	LOGGER_LOG logger_log;
+
+	/* subscriptions */
+	LIST_HANDLE subscription_list;
+
+	/* decode frame */
+	RECEIVE_FRAME_STATE receive_frame_state;
+	size_t receive_frame_pos;
+	uint32_t receive_frame_size;
+	uint32_t type_specific_size;
+	uint8_t receive_frame_doff;
+	uint8_t receive_frame_type;
+	SUBSCRIPTION* receive_frame_subscription;
+	unsigned char* receive_frame_bytes;
+	ON_FRAME_CODEC_ERROR on_frame_codec_error;
+	void* on_frame_codec_error_callback_context;
+
+	/* encode frame */
+	ENCODE_FRAME_STATE encode_frame_state;
+
+	/* configuration */
+	uint32_t max_frame_size;
+} FRAME_CODEC_INSTANCE;
+
+static bool find_subscription_by_frame_type(LIST_ITEM_HANDLE list_item, const void* match_context)
+{
+	bool result;
+	SUBSCRIPTION* subscription = (SUBSCRIPTION*)list_item_get_value(list_item);
+
+	if (subscription == NULL)
+	{
+		result = false;
+	}
+	else
+	{
+		result = subscription->frame_type == *((uint8_t*)match_context) ? true : false;
+	}
+
+	return result;
+}
+
+FRAME_CODEC_HANDLE frame_codec_create(ON_FRAME_CODEC_ERROR on_frame_codec_error, void* callback_context, LOGGER_LOG logger_log)
+{
+	FRAME_CODEC_INSTANCE* result;
+
+	/* Codes_SRS_FRAME_CODEC_01_020: [If the on_frame_codec_error argument is NULL, frame_codec_create shall return NULL.] */
+	/* Codes_SRS_FRAME_CODEC_01_104: [The callback_context shall be allowed to be NULL.] */
+	if (on_frame_codec_error == NULL)
+	{
+		result = NULL;
+	}
+	else
+	{
+		result = amqpalloc_malloc(sizeof(FRAME_CODEC_INSTANCE));
+		/* Codes_SRS_FRAME_CODEC_01_022: [If allocating memory for the frame_codec instance fails, frame_codec_create shall return NULL.] */
+		if (result != NULL)
+		{
+			/* Codes_SRS_FRAME_CODEC_01_021: [frame_codec_create shall create a new instance of frame_codec and return a non-NULL handle to it on success.] */
+			result->logger_log = logger_log;
+			result->encode_frame_state = ENCODE_FRAME_STATE_IDLE;
+			result->receive_frame_state = RECEIVE_FRAME_STATE_FRAME_SIZE;
+			result->on_frame_codec_error = on_frame_codec_error;
+			result->on_frame_codec_error_callback_context = callback_context;
+			result->receive_frame_pos = 0;
+			result->receive_frame_size = 0;
+			result->receive_frame_bytes = NULL;
+			result->subscription_list = list_create();
+
+			/* Codes_SRS_FRAME_CODEC_01_082: [The initial max_frame_size_shall be 512.] */
+			result->max_frame_size = 512;
+		}
+	}
+
+	return result;
+}
+
+void frame_codec_destroy(FRAME_CODEC_HANDLE frame_codec)
+{
+	/* Codes_SRS_FRAME_CODEC_01_024: [If frame_codec is NULL, frame_codec_destroy shall do nothing.] */
+	if (frame_codec != NULL)
+	{
+		FRAME_CODEC_INSTANCE* frame_codec_data = (FRAME_CODEC_INSTANCE*)frame_codec;
+
+		list_destroy(frame_codec_data->subscription_list);
+		if (frame_codec_data->receive_frame_bytes != NULL)
+		{
+			amqpalloc_free(frame_codec_data->receive_frame_bytes);
+		}
+
+		/* Codes_SRS_FRAME_CODEC_01_023: [frame_codec_destroy shall free all resources associated with a frame_codec instance.] */
+		amqpalloc_free(frame_codec);
+	}
+}
+
+int frame_codec_set_max_frame_size(FRAME_CODEC_HANDLE frame_codec, uint32_t max_frame_size)
+{
+	int result;
+	FRAME_CODEC_INSTANCE* frame_codec_data = (FRAME_CODEC_INSTANCE*)frame_codec;
+
+	/* Codes_SRS_FRAME_CODEC_01_077: [If frame_codec is NULL, frame_codec_set_max_frame_size shall return a non-zero value.] */
+	if ((frame_codec == NULL) ||
+		/* Codes_SRS_FRAME_CODEC_01_078: [If max_frame_size is invalid according to the AMQP standard, frame_codec_set_max_frame_size shall return a non-zero value.] */
+		(max_frame_size < FRAME_HEADER_SIZE) ||
+		/* Codes_SRS_FRAME_CODEC_01_081: [If a frame being decoded already has a size bigger than the max_frame_size argument then frame_codec_set_max_frame_size shall return a non-zero value and the previous frame size shall be kept.] */
+		((max_frame_size < frame_codec_data->receive_frame_size) && (frame_codec_data->receive_frame_state != RECEIVE_FRAME_STATE_FRAME_SIZE)) ||
+		/* Codes_SRS_FRAME_CODEC_01_097: [Setting a frame size on a frame_codec that had a decode error shall fail.] */
+		(frame_codec_data->receive_frame_state == RECEIVE_FRAME_STATE_ERROR) ||
+		/* Codes_SRS_FRAME_CODEC_01_098: [Setting a frame size on a frame_codec that had an encode error shall fail.] */
+		(frame_codec_data->encode_frame_state == ENCODE_FRAME_STATE_ERROR))
+	{
+		result = __LINE__;
+	}
+	else
+	{
+		/* Codes_SRS_FRAME_CODEC_01_075: [frame_codec_set_max_frame_size shall set the maximum frame size for a frame_codec.] */
+		/* Codes_SRS_FRAME_CODEC_01_079: [The new frame size shall take effect immediately, even for a frame that is being decoded at the time of the call.] */
+		frame_codec_data->max_frame_size = max_frame_size;
+
+		/* Codes_SRS_FRAME_CODEC_01_076: [On success, frame_codec_set_max_frame_size shall return 0.] */
+		result = 0;
+	}
+	return result;
+}
+
+/* Codes_SRS_FRAME_CODEC_01_001: [Frames are divided into three distinct areas: a fixed width frame header, a variable width extended header, and a variable width frame body.] */
+/* Codes_SRS_FRAME_CODEC_01_002: [frame header The frame header is a fixed size (8 byte) structure that precedes each frame.] */
+/* Codes_SRS_FRAME_CODEC_01_003: [The frame header includes mandatory information necessary to parse the rest of the frame including size and type information.] */
+/* Codes_SRS_FRAME_CODEC_01_004: [extended header The extended header is a variable width area preceding the frame body.] */
+/* Codes_SRS_FRAME_CODEC_01_007: [frame body The frame body is a variable width sequence of bytes the format of which depends on the frame type.] */
+/* Codes_SRS_FRAME_CODEC_01_028: [The sequence of bytes shall be decoded according to the AMQP ISO.] */
+/* Codes_SRS_FRAME_CODEC_01_029: [The sequence of bytes does not have to be a complete frame, frame_codec shall be responsible for maintaining decoding state between frame_codec_receive_bytes calls.] */
+int frame_codec_receive_bytes(FRAME_CODEC_HANDLE frame_codec, const unsigned char* buffer, size_t size)
+{
+	int result;
+	FRAME_CODEC_INSTANCE* frame_codec_data = (FRAME_CODEC_INSTANCE*)frame_codec;
+
+	/* Codes_SRS_FRAME_CODEC_01_026: [If frame_codec or buffer are NULL, frame_codec_receive_bytes shall return a non-zero value.] */
+	if ((frame_codec == NULL) ||
+		(buffer == NULL) ||
+		/* Codes_SRS_FRAME_CODEC_01_027: [If size is zero, frame_codec_receive_bytes shall return a non-zero value.] */
+		(size == 0))
+	{
+		result = __LINE__;
+	}
+	else
+	{
+		while (size > 0)
+		{
+			switch (frame_codec_data->receive_frame_state)
+			{
+			default:
+			case RECEIVE_FRAME_STATE_ERROR:
+				/* Codes_SRS_FRAME_CODEC_01_074: [If a decoding error is detected, any subsequent calls on frame_codec_data_receive_bytes shall fail.] */
+				result = __LINE__;
+				size = 0;
+				break;
+
+				/* Codes_SRS_FRAME_CODEC_01_008: [SIZE Bytes 0-3 of the frame header contain the frame size.] */
+			case RECEIVE_FRAME_STATE_FRAME_SIZE:
+				/* Codes_SRS_FRAME_CODEC_01_009: [This is an unsigned 32-bit integer that MUST contain the total frame size of the frame header, extended header, and frame body.] */
+				frame_codec_data->receive_frame_size += buffer[0] << (24 - frame_codec_data->receive_frame_pos * 8);
+				buffer++;
+				size--;
+				frame_codec_data->receive_frame_pos++;
+
+				if (frame_codec_data->receive_frame_pos == 4)
+				{
+					/* Codes_SRS_FRAME_CODEC_01_010: [The frame is malformed if the size is less than the size of the frame header (8 bytes).] */
+					if ((frame_codec_data->receive_frame_size < FRAME_HEADER_SIZE) ||
+						/* Codes_SRS_FRAME_CODEC_01_096: [If a frame bigger than the current max frame size is received, frame_codec_receive_bytes shall fail and return a non-zero value.] */
+						(frame_codec_data->receive_frame_size > frame_codec_data->max_frame_size))
+					{
+						/* Codes_SRS_FRAME_CODEC_01_074: [If a decoding error is detected, any subsequent calls on frame_codec_data_receive_bytes shall fail.] */
+						frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_ERROR;
+						/* Codes_SRS_FRAME_CODEC_01_103: [Upon any decode error, if an error callback has been passed to frame_codec_create, then the error callback shall be called with the context argument being the on_frame_codec_error_callback_context argument passed to frame_codec_create.] */
+						frame_codec_data->on_frame_codec_error(frame_codec_data->on_frame_codec_error_callback_context);
+
+						result = __LINE__;
+					}
+					else
+					{
+						frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_DOFF;
+						result = 0;
+					}
+				}
+				else
+				{
+					result = 0;
+				}
+
+				break;
+
+			case RECEIVE_FRAME_STATE_DOFF:
+				/* Codes_SRS_FRAME_CODEC_01_011: [DOFF Byte 4 of the frame header is the data offset.] */
+				/* Codes_SRS_FRAME_CODEC_01_013: [The value of the data offset is an unsigned, 8-bit integer specifying a count of 4-byte words.] */
+				/* Codes_SRS_FRAME_CODEC_01_012: [This gives the position of the body within the frame.] */
+				frame_codec_data->receive_frame_doff = buffer[0];
+				buffer++;
+				size--;
+
+				/* Codes_SRS_FRAME_CODEC_01_014: [Due to the mandatory 8-byte frame header, the frame is malformed if the value is less than 2.] */
+				if (frame_codec_data->receive_frame_doff < 2)
+				{
+					/* Codes_SRS_FRAME_CODEC_01_074: [If a decoding error is detected, any subsequent calls on frame_codec_data_receive_bytes shall fail.] */
+					frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_ERROR;
+
+					/* Codes_SRS_FRAME_CODEC_01_103: [Upon any decode error, if an error callback has been passed to frame_codec_create, then the error callback shall be called with the context argument being the on_frame_codec_error_callback_context argument passed to frame_codec_create.] */
+					frame_codec_data->on_frame_codec_error(frame_codec_data->on_frame_codec_error_callback_context);
+
+					result = __LINE__;
+				}
+				else
+				{
+					frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_FRAME_TYPE;
+					result = 0;
+				}
+
+				break;
+
+			case RECEIVE_FRAME_STATE_FRAME_TYPE:
+			{
+				LIST_ITEM_HANDLE item_handle;
+				frame_codec_data->type_specific_size = (frame_codec_data->receive_frame_doff * 4) - 6;
+
+				/* Codes_SRS_FRAME_CODEC_01_015: [TYPE Byte 5 of the frame header is a type code.] */
+				frame_codec_data->receive_frame_type = buffer[0];
+				buffer++;
+				size--;
+
+				/* Codes_SRS_FRAME_CODEC_01_035: [After successfully registering a callback for a certain frame type, when subsequently that frame type is received the callbacks shall be invoked, passing to it the received frame and the callback_context value.] */
+				item_handle = list_find(frame_codec_data->subscription_list, find_subscription_by_frame_type, &frame_codec_data->receive_frame_type);
+				if (item_handle == NULL)
+				{
+					frame_codec_data->receive_frame_subscription = NULL;
+					frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_TYPE_SPECIFIC;
+					result = 0;
+					break;
+				}
+				else
+				{
+					frame_codec_data->receive_frame_subscription = (SUBSCRIPTION*)list_item_get_value(item_handle);
+					if (frame_codec_data->receive_frame_subscription == NULL)
+					{
+						frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_TYPE_SPECIFIC;
+						result = 0;
+						break;
+					}
+					else
+					{
+						frame_codec_data->receive_frame_pos = 0;
+
+						/* Codes_SRS_FRAME_CODEC_01_102: [frame_codec_receive_bytes shall allocate memory to hold the frame_body bytes.] */
+						frame_codec_data->receive_frame_bytes = (unsigned char*)amqpalloc_malloc(frame_codec_data->receive_frame_size - 6);
+						if (frame_codec_data->receive_frame_bytes == NULL)
+						{
+							/* Codes_SRS_FRAME_CODEC_01_101: [If the memory for the frame_body bytes cannot be allocated, frame_codec_receive_bytes shall fail and return a non-zero value.] */
+							/* Codes_SRS_FRAME_CODEC_01_030: [If a decoding error occurs, frame_codec_data_receive_bytes shall return a non-zero value.] */
+							/* Codes_SRS_FRAME_CODEC_01_074: [If a decoding error is detected, any subsequent calls on frame_codec_data_receive_bytes shall fail.] */
+							frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_ERROR;
+
+							/* Codes_SRS_FRAME_CODEC_01_103: [Upon any decode error, if an error callback has been passed to frame_codec_create, then the error callback shall be called with the context argument being the on_frame_codec_error_callback_context argument passed to frame_codec_create.] */
+							frame_codec_data->on_frame_codec_error(frame_codec_data->on_frame_codec_error_callback_context);
+
+							result = __LINE__;
+							break;
+						}
+						else
+						{
+							frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_TYPE_SPECIFIC;
+							result = 0;
+							break;
+						}
+					}
+				}
+			}
+
+			case RECEIVE_FRAME_STATE_TYPE_SPECIFIC:
+			{
+				uint32_t to_copy = frame_codec_data->type_specific_size - frame_codec_data->receive_frame_pos;
+				if (to_copy > size)
+				{
+					to_copy = size;
+				}
+
+				if (frame_codec_data->receive_frame_subscription != NULL)
+				{
+					(void)memcpy(&frame_codec_data->receive_frame_bytes[frame_codec_data->receive_frame_pos], buffer, to_copy);
+					frame_codec_data->receive_frame_pos += to_copy;
+					buffer += to_copy;
+					size -= to_copy;
+				}
+				else
+				{
+					frame_codec_data->receive_frame_pos += to_copy;
+					buffer += to_copy;
+					size -= to_copy;
+				}
+
+				if (frame_codec_data->receive_frame_pos == frame_codec_data->type_specific_size)
+				{
+					if (frame_codec_data->receive_frame_size == FRAME_HEADER_SIZE)
+					{
+						if (frame_codec_data->receive_frame_subscription != NULL)
+						{
+							/* Codes_SRS_FRAME_CODEC_01_031: [When a complete frame is successfully decoded it shall be indicated to the upper layer by invoking the on_frame_received passed to frame_codec_subscribe.] */
+							/* Codes_SRS_FRAME_CODEC_01_032: [Besides passing the frame information, the callback_context value passed to frame_codec_data_subscribe shall be passed to the on_frame_received function.] */
+							/* Codes_SRS_FRAME_CODEC_01_005: [This is an extension point defined for future expansion.] */
+							/* Codes_SRS_FRAME_CODEC_01_006: [The treatment of this area depends on the frame type.] */
+							/* Codes_SRS_FRAME_CODEC_01_100: [If the frame body size is 0, the frame_body pointer passed to on_frame_received shall be NULL.] */
+							frame_codec_data->receive_frame_subscription->on_frame_received(frame_codec_data->receive_frame_subscription->callback_context, frame_codec_data->receive_frame_bytes, frame_codec_data->type_specific_size, NULL, 0);
+							amqpalloc_free(frame_codec_data->receive_frame_bytes);
+							frame_codec_data->receive_frame_bytes = NULL;
+						}
+
+						frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_FRAME_SIZE;
+						frame_codec_data->receive_frame_size = 0;
+					}
+					else
+					{
+						frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_FRAME_BODY;
+					}
+
+					frame_codec_data->receive_frame_pos = 0;
+				}
+
+				result = 0;
+				break;
+			}
+
+			case RECEIVE_FRAME_STATE_FRAME_BODY:
+			{
+				uint32_t frame_body_size = frame_codec_data->receive_frame_size - (frame_codec_data->receive_frame_doff * 4);
+				uint32_t to_copy = frame_body_size - frame_codec_data->receive_frame_pos;
+
+				if (to_copy > size)
+				{
+					to_copy = size;
+				}
+
+				(void)memcpy(frame_codec_data->receive_frame_bytes + frame_codec_data->receive_frame_pos + frame_codec_data->type_specific_size, buffer, to_copy);
+
+				buffer += to_copy;
+				size -= to_copy;
+				frame_codec_data->receive_frame_pos += to_copy;
+
+				if (frame_codec_data->receive_frame_pos == frame_body_size)
+				{
+					if (frame_codec_data->receive_frame_subscription != NULL)
+					{
+						/* Codes_SRS_FRAME_CODEC_01_031: [When a complete frame is successfully decoded it shall be indicated to the upper layer by invoking the on_frame_received passed to frame_codec_subscribe.] */
+						/* Codes_SRS_FRAME_CODEC_01_032: [Besides passing the frame information, the callback_context value passed to frame_codec_data_subscribe shall be passed to the on_frame_received function.] */
+						/* Codes_SRS_FRAME_CODEC_01_005: [This is an extension point defined for future expansion.] */
+						/* Codes_SRS_FRAME_CODEC_01_006: [The treatment of this area depends on the frame type.] */
+						/* Codes_SRS_FRAME_CODEC_01_099: [A pointer to the frame_body bytes shall also be passed to the on_frame_received.] */
+						frame_codec_data->receive_frame_subscription->on_frame_received(frame_codec_data->receive_frame_subscription->callback_context, frame_codec_data->receive_frame_bytes, frame_codec_data->type_specific_size, frame_codec_data->receive_frame_bytes + frame_codec_data->type_specific_size, frame_body_size);
+						amqpalloc_free(frame_codec_data->receive_frame_bytes);
+						frame_codec_data->receive_frame_bytes = NULL;
+					}
+
+					frame_codec_data->receive_frame_state = RECEIVE_FRAME_STATE_FRAME_SIZE;
+					frame_codec_data->receive_frame_pos = 0;
+					frame_codec_data->receive_frame_size = 0;
+				}
+				result = 0;
+
+				break;
+			}
+			}
+		}
+	}
+
+	return result;
+}
+
+/* Codes_SRS_FRAME_CODEC_01_033: [frame_codec_subscribe subscribes for a certain type of frame received by the frame_codec instance identified by frame_codec.] */
+int frame_codec_subscribe(FRAME_CODEC_HANDLE frame_codec, uint8_t type, ON_FRAME_RECEIVED on_frame_received, void* callback_context)
+{
+	int result;
+
+	/* Codes_SRS_FRAME_CODEC_01_034: [If any of the frame_codec or on_frame_received arguments is NULL, frame_codec_subscribe shall return a non-zero value.] */
+	if ((frame_codec == NULL) ||
+		(on_frame_received == NULL))
+	{
+		result = __LINE__;
+	}
+	else
+	{
+		FRAME_CODEC_INSTANCE* frame_codec_data = (FRAME_CODEC_INSTANCE*)frame_codec;
+		SUBSCRIPTION* subscription;
+
+		/* Codes_SRS_FRAME_CODEC_01_036: [Only one callback pair shall be allowed to be registered for a given frame type.] */
+		/* find the subscription for this frame type */
+		LIST_ITEM_HANDLE list_item = list_find(frame_codec_data->subscription_list, find_subscription_by_frame_type, &type);
+		if (list_item != NULL)
+		{
+			subscription = (SUBSCRIPTION*)list_item_get_value(list_item);
+			if (subscription == NULL)
+			{
+				/* Codes_SRS_FRAME_CODEC_01_037: [If any failure occurs while performing the subscribe operation, frame_codec_subscribe shall return a non-zero value.] */
+				result = __LINE__;
+			}
+			else
+			{
+				/* a subscription was found */
+				subscription->on_frame_received = on_frame_received;
+				subscription->callback_context = callback_context;
+
+				/* Codes_SRS_FRAME_CODEC_01_087: [On success, frame_codec_subscribe shall return zero.] */
+				result = 0;
+			}
+		}
+		else
+		{
+			/* add a new subscription */
+			subscription = (SUBSCRIPTION*)amqpalloc_malloc(sizeof(SUBSCRIPTION));
+			/* Codes_SRS_FRAME_CODEC_01_037: [If any failure occurs while performing the subscribe operation, frame_codec_subscribe shall return a non-zero value.] */
+			if (subscription == NULL)
+			{
+				result = __LINE__;
+			}
+			else
+			{
+				subscription->on_frame_received = on_frame_received;
+				subscription->callback_context = callback_context;
+				subscription->frame_type = type;
+
+				/* Codes_SRS_FRAME_CODEC_01_037: [If any failure occurs while performing the subscribe operation, frame_codec_subscribe shall return a non-zero value.] */
+				if (list_add(frame_codec_data->subscription_list, subscription) == NULL)
+				{
+					amqpalloc_free(subscription);
+					result = __LINE__;
+				}
+				else
+				{
+					/* Codes_SRS_FRAME_CODEC_01_087: [On success, frame_codec_subscribe shall return zero.] */
+					result = 0;
+				}
+			}
+		}
+	}
+
+	return result;
+}
+
+int frame_codec_unsubscribe(FRAME_CODEC_HANDLE frame_codec, uint8_t type)
+{
+	int result;
+
+	/* Codes_SRS_FRAME_CODEC_01_039: [If frame_codec is NULL, frame_codec_unsubscribe shall return a non-zero value.] */
+	if (frame_codec == NULL)
+	{
+		result = __LINE__;
+	}
+	else
+	{
+		FRAME_CODEC_INSTANCE* frame_codec_data = (FRAME_CODEC_INSTANCE*)frame_codec;
+		LIST_ITEM_HANDLE list_item = list_find(frame_codec_data->subscription_list, find_subscription_by_frame_type, &type);
+
+		if (list_item == NULL)
+		{
+			/* Codes_SRS_FRAME_CODEC_01_040: [If no subscription for the type frame type exists, frame_codec_unsubscribe shall return a non-zero value.] */
+			/* Codes_SRS_FRAME_CODEC_01_041: [If any failure occurs while performing the unsubscribe operation, frame_codec_unsubscribe shall return a non-zero value.] */
+			result = __LINE__;
+		}
+		else
+		{
+			SUBSCRIPTION* subscription = (SUBSCRIPTION*)list_item_get_value(list_item);
+			if (subscription == NULL)
+			{
+				/* Codes_SRS_FRAME_CODEC_01_041: [If any failure occurs while performing the unsubscribe operation, frame_codec_unsubscribe shall return a non-zero value.] */
+				result = __LINE__;
+			}
+			else
+			{
+				amqpalloc_free(subscription);
+				if (list_remove(frame_codec_data->subscription_list, list_item) != 0)
+				{
+					/* Codes_SRS_FRAME_CODEC_01_041: [If any failure occurs while performing the unsubscribe operation, frame_codec_unsubscribe shall return a non-zero value.] */
+					result = __LINE__;
+				}
+				else
+				{
+					/* Codes_SRS_FRAME_CODEC_01_038: [frame_codec_unsubscribe removes a previous subscription for frames of type type and on success it shall return 0.] */
+					result = 0;
+				}
+			}
+		}
+	}
+
+	return result;
+}
+
+int frame_codec_encode_frame(FRAME_CODEC_HANDLE frame_codec, uint8_t type, const PAYLOAD* payloads, size_t payload_count, const unsigned char* type_specific_bytes, uint32_t type_specific_size, ON_BYTES_ENCODED on_bytes_encoded, void* callback_context)
+{
+	int result;
+	uint32_t frame_body_offset = type_specific_size + 6;
+
+	/* round up to the 4 bytes for doff */
+	/* Codes_SRS_FRAME_CODEC_01_067: [The value of the data offset is an unsigned, 8-bit integer specifying a count of 4-byte words.] */
+	/* Codes_SRS_FRAME_CODEC_01_068: [Due to the mandatory 8-byte frame header, the frame is malformed if the value is less than 2.] */
+	uint8_t doff = (frame_body_offset + 3) / 4;
+	size_t frame_size;
+	FRAME_CODEC_INSTANCE* frame_codec_data = (FRAME_CODEC_INSTANCE*)frame_codec;
+	uint32_t frame_body_size = 0;
+	size_t i;
+
+	for (i = 0; i < payload_count; i++)
+	{
+		frame_body_size += payloads[i].length;
+	}
+
+	frame_body_offset = doff * 4;
+
+	/* Codes_SRS_FRAME_CODEC_01_063: [This is an unsigned 32-bit integer that MUST contain the total frame size of the frame header, extended header, and frame body.] */
+	frame_size = frame_body_size + frame_body_offset;
+
+	/* Codes_SRS_FRAME_CODEC_01_044: [If the argument frame_codec is NULL, frame_codec_encode_frame shall return a non-zero value.] */
+	if ((frame_codec == NULL) ||
+		/* Codes_SRS_FRAME_CODEC_01_091: [If the argument type_specific_size is greater than 0 and type_specific_bytes is NULL, frame_codec_encode_frame shall return a non-zero value.] */
+		((type_specific_size > 0) && (type_specific_bytes == NULL)) ||
+		/* Codes_SRS_FRAME_CODEC_01_092: [If type_specific_size is too big to allow encoding the frame according to the AMQP ISO then frame_codec_encode_frame shall return a non-zero value.] */
+		(type_specific_size > MAX_TYPE_SPECIFIC_SIZE) ||
+		(frame_codec_data->encode_frame_state == ENCODE_FRAME_STATE_ERROR) ||
+		/* Codes_SRS_FRAME_CODEC_01_095: [If the frame_size needed for the frame is bigger than the maximum frame size, frame_codec_encode_frame shall fail and return a non-zero value.] */
+		(frame_size > frame_codec_data->max_frame_size))
+	{
+		result = __LINE__;
+	}
+	else
+	{
+		uint8_t padding_byte_count = frame_body_offset - type_specific_size - 6;
+
+		/* Codes_SRS_FRAME_CODEC_01_042: [frame_codec_encode_frame encodes the header and type specific bytes of a frame that has frame_payload_size bytes.]  */
+		/* Codes_SRS_FRAME_CODEC_01_055: [Frames are divided into three distinct areas: a fixed width frame header, a variable width extended header, and a variable width frame body.] */
+		/* Codes_SRS_FRAME_CODEC_01_056: [frame header The frame header is a fixed size (8 byte) structure that precedes each frame.] */
+		/* Codes_SRS_FRAME_CODEC_01_057: [The frame header includes mandatory information necessary to parse the rest of the frame including size and type information.] */
+		/* Codes_SRS_FRAME_CODEC_01_058: [extended header The extended header is a variable width area preceding the frame body.] */
+		/* Codes_SRS_FRAME_CODEC_01_059: [This is an extension point defined for future expansion.] */
+		/* Codes_SRS_FRAME_CODEC_01_060: [The treatment of this area depends on the frame type.]*/
+		/* Codes_SRS_FRAME_CODEC_01_062: [SIZE Bytes 0-3 of the frame header contain the frame size.] */
+		/* Codes_SRS_FRAME_CODEC_01_063: [This is an unsigned 32-bit integer that MUST contain the total frame size of the frame header, extended header, and frame body.] */
+		/* Codes_SRS_FRAME_CODEC_01_064: [The frame is malformed if the size is less than the size of the frame header (8 bytes).] */
+		unsigned char frame_header[] =
+		{
+			(frame_size >> 24) & 0xFF,
+			(frame_size >> 16) & 0xFF,
+			(frame_size >> 8) & 0xFF,
+			frame_size & 0xFF,
+			/* Codes_SRS_FRAME_CODEC_01_065: [DOFF Byte 4 of the frame header is the data offset.] */
+			doff,
+			/* Codes_SRS_FRAME_CODEC_01_069: [TYPE Byte 5 of the frame header is a type code.] */
+			type
+		};
+
+		/* Codes_SRS_FRAME_CODEC_01_088: [Encoded bytes shall be passed to the on_bytes_encoded callback.] */
+		on_bytes_encoded(callback_context, frame_header, sizeof(frame_header), ((frame_body_size + type_specific_bytes + padding_byte_count) == 0) ? true : false);
+
+		/* Codes_SRS_FRAME_CODEC_01_088: [Encoded bytes shall be passed to the on_bytes_encoded callback.] */
+		if (type_specific_size > 0)
+		{
+			on_bytes_encoded(callback_context, type_specific_bytes, type_specific_size, ((frame_body_size + padding_byte_count) == 0) ? true : false);
+		}
+
+		/* send padding bytes */
+		/* Codes_SRS_FRAME_CODEC_01_090: [If the type_specific_size – 2 does not divide by 4, frame_codec_encode_frame shall pad the type_specific bytes with zeroes so that type specific data is according to the AMQP ISO.] */
+		unsigned char padding_bytes[] = { 0x00, 0x00, 0x00 };
+
+		/* Codes_SRS_FRAME_CODEC_01_088: [Encoded bytes shall be passed to the on_bytes_encoded callback.] */
+		if (padding_byte_count > 0)
+		{
+			on_bytes_encoded(callback_context, padding_bytes, padding_byte_count, (payload_count == 0) ? true : false);
+		}
+
+		for (i = 0; i < payload_count; i++)
+		{
+			/* Codes_SRS_FRAME_CODEC_01_088: [Encoded bytes shall be passed to the on_bytes_encoded callback.] */
+			on_bytes_encoded(callback_context, payloads[i].bytes, payloads[i].length, (i == payload_count - 1) ? true : false);
+		}
+
+		/* Codes_SRS_FRAME_CODEC_01_043: [On success it shall return 0.] */
+		result = 0;
+	}
+
+	return result;
+}