diff options
Diffstat (limited to 'lib/i2ctcp')
| -rw-r--r-- | lib/i2ctcp/CMakeLists.txt | 14 | ||||
| -rw-r--r-- | lib/i2ctcp/i2ctcpv1.c | 52 | ||||
| -rw-r--r-- | lib/i2ctcp/i2ctcpv1.h | 71 | ||||
| -rw-r--r-- | lib/i2ctcp/makefile | 4 | ||||
| -rw-r--r-- | lib/i2ctcp/readme.md | 25 |
5 files changed, 166 insertions, 0 deletions
diff --git a/lib/i2ctcp/CMakeLists.txt b/lib/i2ctcp/CMakeLists.txt new file mode 100644 index 0000000..b47b1d7 --- /dev/null +++ b/lib/i2ctcp/CMakeLists.txt @@ -0,0 +1,14 @@ +cmake_minimum_required(VERSION 3.29) + +set(CMAKE_C_STANDARD 11) +set(CMAKE_CXX_STANDARD 17) +set(CMAKE_EXPORT_COMPILE_COMMANDS 1) + +project(i2ctcp C CXX) + +add_subdirectory(../mpack ${CMAKE_CURRENT_BINARY_DIR}/mpack) + +add_library(i2ctcp STATIC ./i2ctcpv1.c) +target_link_libraries(i2ctcp mpack) +target_include_directories(i2ctcp SYSTEM INTERFACE .) + diff --git a/lib/i2ctcp/i2ctcpv1.c b/lib/i2ctcp/i2ctcpv1.c new file mode 100644 index 0000000..944df3a --- /dev/null +++ b/lib/i2ctcp/i2ctcpv1.c @@ -0,0 +1,52 @@ +#include <mpack.h> +#ifndef MIN +#define MIN(a,b) (((a) < (b)) ? (a) : (b)) +#endif + +#include "i2ctcpv1.h" + +int i2ctcp_read(i2ctcp_msg_t * target, const char * buf, size_t buf_sz) { + mpack_reader_t reader; + mpack_reader_init_data(&reader, buf, buf_sz); + + // at start of message + if (target->_rdata == 0) { + target->addr = mpack_expect_u16(&reader); + target->length = target->_rdata = mpack_expect_bin(&reader); + if (mpack_reader_error(&reader) != mpack_ok) return -1; + target->data = (char *) malloc(target->length); + + // seek forward in buf to where binary data begins (to avoid having to read + // from private member reader.data in the memcpy below) + buf += buf_sz - mpack_reader_remaining(&reader, NULL); + } + + // continue reading chunks of target->data until the amount of bytes + // specified in target->length + size_t to_read = MIN(mpack_reader_remaining(&reader, NULL), target->_rdata); + char * data = target->data + target->length - target->_rdata; + memcpy(data, buf, to_read); + target->_rdata -= to_read; + // NOTE: memcpy is used here because mpack_read_bytes requires that a tag was + // opened, which is not the case for the chunks following the initial mpack + // header + + // if rdata = 0, the message was completely read + return target->_rdata; +} + +void i2ctcp_read_reset(i2ctcp_msg_t * target) { + target->_rdata = 0; +} + +bool i2ctcp_write(const i2ctcp_msg_t * target, char ** buf, size_t * buf_sz) { + mpack_writer_t writer; + mpack_writer_init_growable(&writer, buf, buf_sz); + + mpack_write_u16(&writer, target->addr); + mpack_write_bin(&writer, target->data, target->length); + + // finish writing + return mpack_writer_destroy(&writer) == mpack_ok; +} + diff --git a/lib/i2ctcp/i2ctcpv1.h b/lib/i2ctcp/i2ctcpv1.h new file mode 100644 index 0000000..799b668 --- /dev/null +++ b/lib/i2ctcp/i2ctcpv1.h @@ -0,0 +1,71 @@ +#pragma once + +#include <stddef.h> +#include <stdint.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/** \brief I2C over TCP message (v1) */ +struct i2ctcp_msg { + uint16_t addr; //!< I^2^C address + char * data; //!< message content + size_t length; //!< message size + size_t _rdata; //!< \private remaining bytes to read until message is complete +}; +typedef struct i2ctcp_msg i2ctcp_msg_t; + +/** + * \brief Read chunk of input stream, and store resulting message in \p target + * + * This function is called for each chunk of data from an input stream, and + * will parse the next puzzle bus message into \p target. The input stream is + * assumed to only contain messages encoded by \p i2ctcp_write() + * + * \param target pointer to struct that will contain the finished message data + * \param buf pointer to input stream data chunk + * \param buf_sz size of \p buf + * + * \returns Integer representing amount of bytes required to finish message, or + * -1 if the message header could not be read. If this function returns 0, the + * message in \p target is complete. + * + * \note target->data will automatically be allocated by this function, even if + * the message is not fully parsed. This variable must be `free()`d by the + * caller after each complete message to prevent memory leaks. + */ +int i2ctcp_read(i2ctcp_msg_t * target, const char * buf, size_t buf_sz); + +/** + * \brief reset the remaining message data counter + * + * Calling this function has the effect of forcing \c i2ctcp_read() to parse + * the next buffer chunk as the start of a new message. This function may be + * called before reading a TCP frame's data to mitigate any synchronization + * issues arising from earlier corrupt or otherwise malformed messages. + */ +void i2ctcp_read_reset(i2ctcp_msg_t * target); + +/** + * \brief Allocate and write a msgpack-formatted message to \p buf + * + * This function allocates a buffer large enough to fit the message specified + * in \p target, and encodes the data in \p target in a format that can be + * decoded later using \p i2ctcp_read() + * + * \param target pointer to struct that contains the message data + * \param buf pointer to \c char* that will contain the formatted message + * \param buf_sz pointer to \c size_t that will represent the final size of \p buf + * + * \returns boolean true if a the message could be encoded successfully, false + * if there was some kind of error + * + * \note the pointer stored in \p buf must be `free()`d by the caller afterwards + */ +bool i2ctcp_write(const i2ctcp_msg_t * target, char ** buf, size_t * buf_sz); + +#ifdef __cplusplus +} +#endif + diff --git a/lib/i2ctcp/makefile b/lib/i2ctcp/makefile new file mode 100644 index 0000000..5ca3fd1 --- /dev/null +++ b/lib/i2ctcp/makefile @@ -0,0 +1,4 @@ +TARGET = $(BUILD_DIR)/libi2ctcp.a + +include ../../lazy.mk + diff --git a/lib/i2ctcp/readme.md b/lib/i2ctcp/readme.md new file mode 100644 index 0000000..d5bfe6d --- /dev/null +++ b/lib/i2ctcp/readme.md @@ -0,0 +1,25 @@ +# i2ctcp (I<sup>2</sup>C over TCP) + +This folder includes protocol (de)serialization functions for sending and +receiving I<sup>2</sup>C messages over TCP. These functions are used by the +[main controller](../main) and the [puzzle box client (pbc)](../client). This +folder does not include any puzzle bus specific code, and the headers for +puzbus are in the [shared](../shared) folder instead. + +[MessagePack][msgpack] (specifically the [mpack][mpack] implementation) is used +for the actual serialization/deserializtion, and the functions in this folder +act as helpers for parsing from chunked data streams. + +To use these functions, include the following statement in your CMakeLists.txt: +```cmake +include(../i2ctcp/include.cmake) +``` + +The functions are available by `#include`ing the `i2ctcpv1.h` header, and are +extensively documented using Doxygen-style comments. + +[msgpack]: https://msgpack.org/ +[mpack]: https://github.com/ludocode/mpack/ + + + |