diff --git a/hdlc/hdlc.c b/hdlc/hdlc.c new file mode 100644 index 0000000..81e4781 --- /dev/null +++ b/hdlc/hdlc.c @@ -0,0 +1,261 @@ +#include "hdlc.h" + +// HDLC Control field bit positions +#define HDLC_CONTROL_S_OR_U_FRAME_BIT 0 +#define HDLC_CONTROL_SEND_SEQ_NO_BIT 1 +#define HDLC_CONTROL_S_FRAME_TYPE_BIT 2 +#define HDLC_CONTROL_POLL_BIT 4 +#define HDLC_CONTROL_RECV_SEQ_NO_BIT 5 + +// HDLC Control type definitions +#define HDLC_CONTROL_TYPE_RECEIVE_READY 0 +#define HDLC_CONTROL_TYPE_RECEIVE_NOT_READY 1 +#define HDLC_CONTROL_TYPE_REJECT 2 +#define HDLC_CONTROL_TYPE_SELECTIVE_REJECT 3 + +static hdlc_state_t hdlc_state = { + .control_escape = 0, + .fcs = FCS_INIT_VALUE, + .start_index = -1, + .end_index = -1, + .src_index = 0, + .dest_index = 0, +}; + +int hdlc_set_state(hdlc_state_t *state) { + if (!state) { + return -EINVAL; + } + + hdlc_state = *state; + return 0; +} + + +int hdlc_get_state(hdlc_state_t *state) { + if (!state) { + return -EINVAL; + } + + *state = hdlc_state; + return 0; +} + +void hdlc_escape_value(char value, char *dest, int *dest_index) { + // Check and escape the value if needed + if ((value == HDLC_FLAG_SEQUENCE) || (value == HDLC_CONTROL_ESCAPE)) { + dest[(*dest_index)++] = HDLC_CONTROL_ESCAPE; + value ^= 0x20; + } + + // Add the value to the destination buffer and increment destination index + dest[(*dest_index)++] = value; +} + +hdlc_control_t hdlc_get_control_type(unsigned char control) { + hdlc_control_t value; + + // Check if the frame is a S-frame (or U-frame) + if (control & (1 << HDLC_CONTROL_S_OR_U_FRAME_BIT)) { + // Check if S-frame type is a Receive Ready (ACK) + if (((control >> HDLC_CONTROL_S_FRAME_TYPE_BIT) & 0x3) + == HDLC_CONTROL_TYPE_RECEIVE_READY) { + value.frame = S_FRAME; + } else { + // Assume it is an NACK since Receive Not Ready, Selective Reject and U-frames are not supported + value.frame = S_FRAME_NACK; + } + + // Add the receive sequence number from the S-frame (or U-frame) + value.seq_no = (control >> HDLC_CONTROL_RECV_SEQ_NO_BIT); + } else { + // It must be an I-frame so add the send sequence number (receive sequence number is not used) + value.frame = I_FRAME; + value.seq_no = (control >> HDLC_CONTROL_SEND_SEQ_NO_BIT); + } + + return value; +} + +unsigned char hdlc_frame_control_type(hdlc_control_t *control) { + unsigned char value = 0; + + switch (control->frame) { + case I_FRAME: + // Create the HDLC I-frame control byte with Poll bit set + value |= (control->seq_no << HDLC_CONTROL_SEND_SEQ_NO_BIT); + value |= (1 << HDLC_CONTROL_POLL_BIT); + break; + case S_FRAME: + // Create the HDLC Receive Ready S-frame control byte with Poll bit cleared + value |= (control->seq_no << HDLC_CONTROL_RECV_SEQ_NO_BIT); + value |= (1 << HDLC_CONTROL_S_OR_U_FRAME_BIT); + break; + case S_FRAME_NACK: + // Create the HDLC Receive Ready S-frame control byte with Poll bit cleared + value |= (control->seq_no << HDLC_CONTROL_RECV_SEQ_NO_BIT); + value |= (HDLC_CONTROL_TYPE_REJECT << HDLC_CONTROL_S_FRAME_TYPE_BIT); + value |= (1 << HDLC_CONTROL_S_OR_U_FRAME_BIT); + break; + } + + return value; +} + +void hdlc_get_data_reset() { + hdlc_get_data_reset_with_state(&hdlc_state); +} + +void hdlc_get_data_reset_with_state(hdlc_state_t *state) { + state->fcs = FCS_INIT_VALUE; + state->start_index = state->end_index = -1; + state->src_index = state->dest_index = 0; + state->control_escape = 0; +} + +//int hdlc_get_data(hdlc_control_t *control, const char *src, +// unsigned int src_len, char *dest, unsigned int *dest_len) +int hdlc_get_data(hdlc_control_t *control, uint8_t *src, + size_t src_len, uint8_t *dest, size_t *dest_len){ + return hdlc_get_data_with_state(&hdlc_state, control, src, src_len, dest, dest_len); +} + +//int hdlc_get_data_with_state(hdlc_state_t *state, hdlc_control_t *control, const char *src, +// unsigned int src_len, char *dest, unsigned int *dest_len) +int hdlc_get_data_with_state(hdlc_state_t *state, hdlc_control_t *control, uint8_t *src, + size_t src_len, uint8_t *dest, size_t *dest_len){ + int ret; + char value; + unsigned int i; + + // Make sure that all parameters are valid + if (!state || !control || !src || !dest || !dest_len) { + return -EINVAL; + } + + // Run through the data bytes + for (i = 0; i < src_len; i++) { + // First find the start flag sequence + if (state->start_index < 0) { + if (src[i] == HDLC_FLAG_SEQUENCE) { + // Check if an additional flag sequence byte is present + if ((i < (src_len - 1)) && (src[i + 1] == HDLC_FLAG_SEQUENCE)) { + // Just loop again to silently discard it (accordingly to HDLC) + continue; + } + + state->start_index = state->src_index; + } + } else { + // Check for end flag sequence + if (src[i] == HDLC_FLAG_SEQUENCE) { + // Check if an additional flag sequence byte is present or earlier received + if (((i < (src_len - 1)) && (src[i + 1] == HDLC_FLAG_SEQUENCE)) + || ((state->start_index + 1) == state->src_index)) { + // Just loop again to silently discard it (accordingly to HDLC) + continue; + } + + state->end_index = state->src_index; + break; + } else if (src[i] == HDLC_CONTROL_ESCAPE) { + state->control_escape = 1; + } else { + // Update the value based on any control escape received + if (state->control_escape) { + state->control_escape = 0; + value = src[i] ^ 0x20; + } else { + value = src[i]; + } + + // Now update the FCS value + state->fcs = calc_fcs(state->fcs, value); + + if (state->src_index == state->start_index + 2) { + // Control field is the second byte after the start flag sequence + *control = hdlc_get_control_type(value); + } else if (state->src_index > (state->start_index + 2)) { + // Start adding the data values after the Control field to the buffer + dest[state->dest_index++] = value; + } + } + } + state->src_index++; + } + + // Check for invalid frame (no start or end flag sequence) + if ((state->start_index < 0) || (state->end_index < 0)) { + // Return no message and make sure destination length is 0 + *dest_len = 0; + ret = -ENOMSG; + } else { + // A frame is at least 4 bytes in size and has a valid FCS value + if ((state->end_index < (state->start_index + 4)) + || (state->fcs != FCS_GOOD_VALUE)) { + // Return FCS error and indicate that data up to end flag sequence in buffer should be discarded + *dest_len = i; + ret = -EIO; + } else { + // Return success and indicate that data up to end flag sequence in buffer should be discarded + *dest_len = state->dest_index - sizeof(state->fcs); + ret = i; + } + + // Reset values for next frame + hdlc_get_data_reset_with_state(state); + } + + return ret; +} + +//int hdlc_frame_data(hdlc_control_t *control, const char *src, +// unsigned int src_len, char *dest, unsigned int *dest_len) +int hdlc_frame_data(hdlc_control_t *control, uint8_t *src, + size_t src_len, uint8_t *dest, size_t *dest_len){ + unsigned int i; + int dest_index = 0; + unsigned char value = 0; + FCS_SIZE fcs = FCS_INIT_VALUE; + + // Make sure that all parameters are valid + if (!control || (!src && (src_len > 0)) || !dest || !dest_len) { + return -EINVAL; + } + + // Start by adding the start flag sequence + dest[dest_index++] = HDLC_FLAG_SEQUENCE; + + // Add the all-station address from HDLC (broadcast) + fcs = calc_fcs(fcs, HDLC_ALL_STATION_ADDR); + hdlc_escape_value(HDLC_ALL_STATION_ADDR, dest, &dest_index); + + // Add the framed control field value + value = hdlc_frame_control_type(control); + fcs = calc_fcs(fcs, value); + hdlc_escape_value(value, dest, &dest_index); + + // Only DATA frames should contain data + if (control->frame == HDLC_FRAME_DATA) { + // Calculate FCS and escape data + for (i = 0; i < src_len; i++) { + fcs = calc_fcs(fcs, src[i]); + hdlc_escape_value(src[i], dest, &dest_index); + } + } + + // Invert the FCS value accordingly to the specification + fcs ^= FCS_INVERT_MASK; + + // Run through the FCS bytes and escape the values + for (i = 0; i < sizeof(fcs); i++) { + value = ((fcs >> (8 * i)) & 0xFF); + hdlc_escape_value(value, dest, &dest_index); + } + + // Add end flag sequence and update length of frame + dest[dest_index++] = HDLC_FLAG_SEQUENCE; + *dest_len = dest_index; + + return 0; +} \ No newline at end of file diff --git a/hdlc/hdlc.h b/hdlc/hdlc.h new file mode 100644 index 0000000..4461414 --- /dev/null +++ b/hdlc/hdlc.h @@ -0,0 +1,126 @@ +// +// Created by 79513 on 15.12.2023. +// + +#ifndef HDLC_H +#define HDLC_H + +#include "fcs.h" +#include +#include "stdint.h" + +/** HDLC start/end flag sequence */ +#define HDLC_FLAG_SEQUENCE 0x7E + +/** HDLC control escape value */ +#define HDLC_CONTROL_ESCAPE 0x7D + +/** HDLC all station address */ +#define HDLC_ALL_STATION_ADDR 0xFF + +/** Supported HDLC frame types */ +typedef enum { + I_FRAME, + S_FRAME, + S_FRAME_NACK, +} hdlc_frame_t; + +/** Control field information */ +typedef struct { + hdlc_frame_t frame; + unsigned char seq_no :3; +} hdlc_control_t; + +/** Variables used in hdlc_get_data and hdlc_get_data_with_state + * to keep track of received buffers + */ +typedef struct { + char control_escape; + FCS_SIZE fcs; + int start_index; + int end_index; + int src_index; + int dest_index; +} hdlc_state_t; + +/** + * Set the hdlc state + * + * @param[in] state The new hdlc state to be used + * @retval 0 Success + * @retval -EINVAL Invalid parameter + */ +int hdlc_set_state(hdlc_state_t *state); + +/** + * Get current hdlc state + * + * @param[out] state Current hdlc state + * @retval 0 Success + * @retval -EINVAL Invalid parameter + */ +int hdlc_get_state(hdlc_state_t *state); + +/** + * Retrieves data from specified buffer containing the HDLC frame. Frames can be + * parsed from multiple buffers e.g. when received via UART. + * + * @param[out] control Control field structure with frame type and sequence number + * @param[in] src Source buffer with frame + * @param[in] src_len Source buffer length + * @param[out] dest Destination buffer (should be able to contain max frame size) + * @param[out] dest_len Destination buffer length + * @retval >=0 Success (size of returned value should be discarded from source buffer) + * @retval -EINVAL Invalid parameter + * @retval -ENOMSG Invalid message + * @retval -EIO Invalid FCS (size of dest_len should be discarded from source buffer) + * + * @see hdlc_get_data_with_state + */ +int hdlc_get_data(hdlc_control_t *control, uint8_t *src, + size_t src_len, uint8_t *dest, size_t *dest_len); + +/** + * Retrieves data from specified buffer containing the HDLC frame. Frames can be + * parsed from multiple buffers e.g. when received via UART. + * + * This function is a variation of @ref hdlc_get_data + * The difference is only in first argument: hdlc_state_t *state + * Data under that pointer is used to keep track of internal buffers. + * + * @see hdlc_get_data + */ +int hdlc_get_data_with_state(hdlc_state_t *state, hdlc_control_t *control, uint8_t *src, + size_t src_len, uint8_t *dest, size_t *dest_len); + +/** + * Resets values used in yahdlc_get_data function to keep track of received buffers + */ +void hdlc_get_data_reset(); + +/** + * This is a variation of @ref hdlc_get_data_reset + * Resets state values that are under the pointer provided as argument + * + * This function need to be called before the first call to hdlc_get_data_with_state + * when custom state storage is used. + * + * @see hdlc_get_data_reset + */ +void hdlc_get_data_reset_with_state(hdlc_state_t *state); + +/** + * Creates HDLC frame with specified data buffer. + * + * @param[in] control Control field structure with frame type and sequence number + * @param[in] src Source buffer with data + * @param[in] src_len Source buffer length + * @param[out] dest Destination buffer (should be bigger than source buffer) + * @param[out] dest_len Destination buffer length + * @retval 0 Success + * @retval -EINVAL Invalid parameter + */ +int hdlc_frame_data(hdlc_control_t *control, uint8_t *src, + size_t src_len, uint8_t *dest, size_t *dest_len); + +#endif //HDLC_H diff --git a/hdlc/main.c b/hdlc/main.c new file mode 100644 index 0000000..2b6f796 --- /dev/null +++ b/hdlc/main.c @@ -0,0 +1,154 @@ +//#include "hdlc.h" +#include "stdio.h" +#include "client.h" +#include +#include + +int main(){ + struct Client hdlc; + connect(&hdlc); + uint8_t frame_data[8]; + get_frame(&hdlc, frame_data, sizeof(frame_data), 0, 0); + + hdlc_get_raw_data(&hdlc, frame_data, sizeof(frame_data)); + + uint8_t send[64]; + uint8_t buffer[134]; + for (int i = 0; i < sizeof(send); i++) { + send[i] = (uint8_t) (rand() % 0x70); + } + send_data(&hdlc, send, sizeof(send_data)); + //get_frame(&hdlc, buffer, sizeof(buffer), send_data, sizeof(send_data)); + + hdlc_get_raw_data(&hdlc, buffer, sizeof(buffer)); + + // test 1 + +// int ret; +// uint8_t frame_data[8], recv_data[8]; +// size_t i, frame_length = 0, recv_length = 0; +// hdlc_control_t control_send, control_recv; + +// // Run through the supported sequence numbers (3-bit) +// for (i = 0; i <= 7; i++) { +// // Initialize the control field structure with frame type and sequence number +// control_send.frame = HDLC_FRAME_ACK; +// control_send.seq_no = i; +// +// // Create an empty frame with the control field information +// ret = hdlc_frame_data(&control_send, NULL, 0, frame_data, &frame_length); +// +// // Get the data from the frame +// ret = hdlc_get_data(&control_recv, frame_data, frame_length, recv_data, +// &recv_length); +// +// // Result should be frame_length minus start flag to be discarded and no bytes received +// if(ret != (int )frame_length - 1){ +// printf("err"); +// } +// } +// if (recv_length != 0){ +// printf("err2"); +// } +// +// if (control_send.frame != control_recv.frame){ +// printf("err3"); +// } +// +// if (control_send.seq_no != control_recv.seq_no){ +// printf("err4"); +// } + + // test 2 + + // Run through the supported sequence numbers (3-bit) +// for (i = 0; i <= 7; i++) { +// // Initialize the control field structure with frame type and sequence number +// control_send.frame = HDLC_FRAME_DATA; +// control_send.seq_no = i; +// +// char* input = "311"; +// uint8_t data = (uint8_t)atoi(input); +// +// // Create an empty frame with the control field information +// ret = hdlc_frame_data(&control_send, &data, 3, frame_data, &frame_length); +// if (ret != 0){ +// printf("err123\n"); +// } +// +// // Get the data from the frame +// ret = hdlc_get_data(&control_recv, frame_data, frame_length, recv_data, +// &recv_length); +// +// // Result should be frame_length minus start flag to be discarded and no bytes received +// if(ret != (int )frame_length - 1){ +// printf("err333\n"); +// } +// if (recv_length != 0){ +// printf("err2\n"); +// } +// +// // Verify the control field information +// if (control_send.frame != control_recv.frame){ +// printf("err3\n"); +// } +// +// if (control_send.seq_no != control_recv.seq_no){ +// printf("err4\n"); +// } +// } + +// int ret; +// hdlc_control_t control; +// uint8_t send_data[512], frame_data[530], recv_data[530]; +// size_t i, frame_length = 0, recv_length = 0, buf_length = 16; +// +// // Initialize data to be send with random values (up to 0x70 to keep below the values to be escaped) +// for (i = 0; i < sizeof(send_data); i++) { +// send_data[i] = (uint8_t) (rand() % 0x70); +// } +// +// // Initialize control field structure and create frame +// control.frame = HDLC_FRAME_DATA; +// ret = hdlc_frame_data(&control, send_data, sizeof(send_data), frame_data, +// &frame_length); +// +// // Check that frame length is maximum 2 bytes larger than data due to escape of FCS value +// if(frame_length >= ((sizeof(send_data) + 6) + 2)){ +// printf("1"); +// } +// if(ret != 0){ +// printf("2"); +// } +// +// // Run though the different buffers (simulating decode of buffers from UART) +// for (i = 0; i <= sizeof(send_data); i += buf_length) { +// // Decode the data +// ret = hdlc_get_data(&control, &frame_data[i], buf_length, recv_data, +// &recv_length); +// +// printf("%zu: %s\n", i, recv_data); +// +// if (i < sizeof(send_data)) { +// // All chunks until the last should return no message and zero length +// if (ret != -ENOMSG){ +// printf("3"); +// } +// if (recv_length != 0){ +// printf("1231"); +// } +// } else { +// if (ret > 7){ +// printf("332"); +// } +// if (recv_length != sizeof(send_data)){ +// printf("88888"); +// } +// // The last chunk should return max 6 frame bytes - 1 start flag sequence byte + 2 byte for the possible +// // escaped FCS = 7 bytes +//// BOOST_CHECK(ret <= 7); +//// BOOST_CHECK_EQUAL(recv_length, sizeof(send_data)); +// //printf("5"); +// } +// } +} \ No newline at end of file