8 files changed, 393 insertions, 0 deletions
diff --git a/shared/bin.c b/shared/bin.c
new file mode 100644
index 0000000..def2aa8
--- /dev/null
+++ b/shared/bin.c
@@ -0,0 +1,11 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <memory.h>
+
+#include "bin.h"
+
+ws_s_bin *ws_bin_s_alloc(uint16_t bytes) {
+	ws_s_bin *temp = malloc(sizeof(ws_s_bin) + sizeof(uint8_t) * bytes);
+	temp->bytes	   = bytes;
+	return temp;
+}
diff --git a/shared/bin.h b/shared/bin.h
new file mode 100644
index 0000000..bfcda0c
--- /dev/null
+++ b/shared/bin.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include <stdint.h>
+
+/** @brief binary data container with length */
+typedef struct {
+  uint16_t bytes;
+  uint8_t data[];
+} ws_s_bin;
+
+/** @brief allocate new ws_s_bin struct */
+ws_s_bin *ws_bin_s_alloc(uint16_t bytes);
+
diff --git a/shared/protocol.c b/shared/protocol.c
new file mode 100644
index 0000000..8887070
--- /dev/null
+++ b/shared/protocol.c
@@ -0,0 +1,147 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "protocol.h"
+#include "util.h"
+
+#define WS_CMD_MAP(parsed_cmd, name, code) \
+	if (strlen(parsed_cmd->argv[0]) == strlen(name) && strncmp(parsed_cmd->argv[0], name, strlen(name)) == 0) return code;
+
+static ws_e_protocol_cmd ws_protocol_get_req_cmd_code(ws_s_protocol_parsed_req_cmd* parsed_cmd) {
+	if (parsed_cmd == NULL) return WS_PROTOCOL_CMD_UNKNOWN; // invalid command
+	WS_CMD_MAP(parsed_cmd, "last-records", WS_PROTOCOL_CMD_LAST_RECORDS);
+
+	return WS_PROTOCOL_CMD_UNKNOWN;
+}
+
+void ws_protocol_parse_req_byte(ws_s_protocol_req_parser_state* state, char input) {
+	switch(input) {
+		case WS_PROTOCOL_C_EOL: {
+			break;
+		}
+
+		case WS_PROTOCOL_C_SPACE: {
+			if (!state->valid) return;
+			state->arg_len++;
+			return;
+		}
+
+		case WS_PROTOCOL_C_NULL: {
+			state->valid = false;
+			return;
+		}
+
+		default: {
+			if (!state->valid) return;
+			state->cmd[state->cmd_len++] = input;
+			state->args_len[state->arg_len] += 1;
+			if (state->cmd_len == WS_PROTOCOL_CMD_BUFFER_LEN) state->valid = false;
+			return;
+		}
+	}
+	// arg_len is used as an index while parsing, so add 1 to get length
+	state->arg_len++;
+
+	// parse cmd into argc and argv
+	if (state->valid) ws_protocol_req_cmd_init(state);
+	// create response
+	ws_s_protocol_res* response = ws_protocol_parse_req_finished(state->target);
+
+	// send response
+	char response_first_line[16];
+	sprintf(response_first_line, "%s,%x\n", response->success == WS_PROTOCOL_CMD_RETURN_OK ? "ok" : "error", response->msg->bytes);
+	ws_protocol_send_data(response_first_line, strlen(response_first_line));
+	if (!response->csh) ws_protocol_send_data((char*) response->msg->data, response->msg->bytes);
+	else (*g_ws_protocol_res_handlers[response->cmd_code])(state->target, response, true);
+	
+	// free response data containers
+	free(response->msg);
+	free(response);
+
+	// reset parser
+	ws_protocol_req_parser_reset(state);
+
+	return;
+}
+
+ws_s_protocol_res* ws_protocol_parse_req_finished(ws_s_protocol_parsed_req_cmd* parsed_cmd) {
+	ws_s_protocol_res* response = malloc(sizeof(ws_s_protocol_res));
+	response->success = WS_PROTOCOL_CMD_RETURN_ERROR;
+	response->csh = false;
+	response->msg = NULL;
+	response->cmd_code = ws_protocol_get_req_cmd_code(parsed_cmd);
+
+	if (response->cmd_code == WS_PROTOCOL_CMD_UNKNOWN) goto ws_protocol_parse_exit;
+	if (response->cmd_code >= WS_PROTOCOL_CMD_AMOUNT) goto ws_protocol_parse_exit;
+
+	ws_protocol_res_handler_t* ws_protocol_res_handler = g_ws_protocol_res_handlers[response->cmd_code];
+	if (ws_protocol_res_handler == NULL) goto ws_protocol_parse_exit;
+	(*ws_protocol_res_handler)(parsed_cmd, response, false);
+
+ws_protocol_parse_exit:
+
+	if (response->msg == NULL) response->msg = ws_bin_s_alloc(0);
+	return response;
+}
+
+void ws_protocol_parse_req_bytes(ws_s_protocol_req_parser_state* state, char* input, unsigned int length) {
+	for (unsigned int i = 0; i < length; i++) ws_protocol_parse_req_byte(state, input[i]);
+}
+
+ws_s_protocol_req_parser_state* ws_protocol_req_parser_alloc() {
+	ws_s_protocol_req_parser_state* parser_state = malloc(sizeof(ws_s_protocol_req_parser_state) + sizeof(uint16_t) * WS_PROTOCOL_CMD_MAX_ARGUMENTS);
+	parser_state->cmd = malloc(sizeof(char) * WS_PROTOCOL_CMD_BUFFER_LEN);
+	parser_state->target = NULL;
+	ws_protocol_req_parser_reset(parser_state);
+	return parser_state;
+}
+
+void ws_protocol_req_cmd_init(ws_s_protocol_req_parser_state* state) {
+	state->target = malloc(sizeof(ws_s_protocol_parsed_req_cmd) + sizeof(char*) * state->arg_len);
+	unsigned int args = WS_MIN(state->arg_len, WS_PROTOCOL_CMD_MAX_ARGUMENTS);
+	for (unsigned int i = 0; i < args; i++)
+		state->target->argv[i] = malloc(sizeof(char) * (state->args_len[i] + 1));
+
+	state->target->argc = args;
+
+	unsigned int head = 0;
+	for (unsigned int i = 0; i < state->arg_len; i++) {
+		strncpy(state->target->argv[i], &state->cmd[head], state->args_len[i]);
+		state->target->argv[i][state->args_len[i]] = 0x00; // terminate argument with null byte
+		head += state->args_len[i];
+	}
+}
+
+void ws_protocol_req_parser_free(ws_s_protocol_req_parser_state* state) {
+	if (state == NULL) return;
+	if (state->target != NULL) ws_protocol_req_cmd_free(state->target);
+	state->target = NULL;
+	free(state->cmd);
+	free(state);
+	return;
+}
+
+void ws_protocol_req_parser_reset(ws_s_protocol_req_parser_state* state) {
+	if (state->target != NULL) ws_protocol_req_cmd_free(state->target);
+	state->target = NULL;
+	state->valid = true;
+	state->cmd_len = 0;
+	state->arg_len = 0;
+	memset(state->args_len, 0, sizeof(uint16_t) * WS_PROTOCOL_CMD_MAX_ARGUMENTS);
+}
+
+void ws_protocol_req_cmd_free(ws_s_protocol_parsed_req_cmd* cmd) {
+	for (int i = 0; i < cmd->argc; i++)
+		free(cmd->argv[i]);
+	free(cmd);
+	return;
+}
+
+unsigned short ws_protocol_get_header_size(ws_s_protocol_res* response) {
+	unsigned short size = 2; // comma and trailing newline
+	if (response->success == WS_PROTOCOL_CMD_RETURN_OK) size += 2; // ok
+	if (response->success == WS_PROTOCOL_CMD_RETURN_ERROR) size += 5; // error
+	size += ws_log16(response->msg->bytes) + 1; // amount of characters for message size (hex)
+	return size;
+}
+\ No newline at end of file
diff --git a/shared/protocol.h b/shared/protocol.h
new file mode 100644
index 0000000..96c039a
--- /dev/null
+++ b/shared/protocol.h
@@ -0,0 +1,151 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "bin.h"
+
+#define WS_PROTOCOL_CMD_MAX_ARGUMENTS (3)
+#define WS_PROTOCOL_CMD_BUFFER_LEN (40)
+
+#define WS_PROTOCOL_CMD_AMOUNT (1)
+
+#define WS_PROTOCOL_C_EOL (0x0a)
+#define WS_PROTOCOL_C_SPACE (0x20)
+#define WS_PROTOCOL_C_NULL (0x00)
+
+/**
+ * @brief parsed request cmd struct, holds arguments similar to argc and argv
+ * provided to `int main()`
+ */
+typedef struct {
+	int argc; /** argument count */
+	char* argv[]; /** argument array, null terminated strings */
+} ws_s_protocol_parsed_req_cmd;
+
+/**
+ * @brief holds parser state variables for `ws_protocol_parse_req_byte` function.
+ * each incoming tcp request should get it's own parser 'instance'
+ */
+typedef struct {
+	ws_s_protocol_parsed_req_cmd* target; /** parsed cmd reference */
+	bool valid; /** command still valid flag */
+	char* cmd; /** raw cmd */
+	uint16_t cmd_len; /** raw cmd string length */
+	uint16_t arg_len; /** amount of arguments */
+	uint16_t args_len[]; /** array of argument lengths */
+} ws_s_protocol_req_parser_state;
+
+/** @brief return values for command handlers */
+typedef enum {
+	WS_PROTOCOL_CMD_RETURN_OK = 0,
+	WS_PROTOCOL_CMD_RETURN_ERROR = 1,
+} ws_e_protocol_cmd_return_value;
+
+/** @brief cmd codes (used to call handlers) */
+typedef enum {
+	WS_PROTOCOL_CMD_UNKNOWN = -1,
+
+	WS_PROTOCOL_CMD_LAST_RECORDS = 0,
+} ws_e_protocol_cmd;
+
+/** @brief request response data struct */
+typedef struct {
+	ws_e_protocol_cmd_return_value success; /** status code for response
+																						validity, defaults to
+																						WS_PROTOCOL_CMD_RETURN_ERROR */
+	bool csh; /** whether the response handler has logic for a custom send
+							handler, false by default */
+	ws_s_bin* msg; /** pointer to response data, uninitialized by default */
+	ws_e_protocol_cmd cmd_code; /** cmd code */
+} ws_s_protocol_res;
+
+/**
+ * @brief allocate parser struct
+ *
+ * @return pointer to newly allocated struct
+ */
+ws_s_protocol_req_parser_state* ws_protocol_req_parser_alloc();
+/** @brief deallocate parser struct, automatically frees all child pointers */
+void ws_protocol_req_parser_free(ws_s_protocol_req_parser_state* state);
+/** @brief reset parser state to parse a new request */
+void ws_protocol_req_parser_reset(ws_s_protocol_req_parser_state* state);
+/**
+ * @brief initialize ws_s_protocol_parsed_req_cmd struct pointer of
+ * ws_s_protocol_req_parser_state (internal only)
+ */
+void ws_protocol_req_cmd_init(ws_s_protocol_req_parser_state* state);
+/** @brief deallocate ws_s_protocol_parsed_req_cmd struct pointer (internal only) */
+void ws_protocol_req_cmd_free(ws_s_protocol_parsed_req_cmd* cmd);
+
+/**
+ * @brief parse incoming data byte by byte until a finished command is detected
+ *
+ * @param state  parser state object, each incoming request should have it's own parser state
+ * @param input  input byte
+ */
+void ws_protocol_parse_req_byte(ws_s_protocol_req_parser_state* state, char input);
+/**
+ * @brief parse incoming data chunk
+ *
+ * @param state  parser state object, each incoming request should have it's own parser state
+ * @param input  input byte array
+ * @param length  input byte array length
+ */
+void ws_protocol_parse_req_bytes(ws_s_protocol_req_parser_state* state, char* input, unsigned int length);
+/**
+ * @brief handle complete command
+ *
+ * this function gets called when ws_protocol_parse_req_byte(s) has detected a
+ * finished command. this function decides which command handler gets called,
+ * given that argv[0] contains a valid command. command argument parsing is
+ * handled by the command handler function.
+ *
+ * @return response
+ *
+ * @param parsed_cmd  cmd parsed into ws_s_protocol_parsed_req_cmd struct
+ */
+ws_s_protocol_res* ws_protocol_parse_req_finished(ws_s_protocol_parsed_req_cmd* parsed_cmd);
+
+/**
+ * @brief create a `last-records` request command
+ * @return ws_s_bin containing the command string
+ */
+ws_s_bin* ws_protocol_req_last_records(unsigned int record_amount);
+
+/**
+ * @brief response handler
+ *
+ * gets fired when the weather station receives a complete command, and returns
+ * a response struct with a success code and an optional message. if
+ * response->csh is set to `true` within the handler, it gets fired a second
+ * time after the response header is sent, but with the `send` parameter set to
+ * `true`. this is so response handlers can send large amounts of data without
+ * allocating large areas of memory.
+ *
+ * @param parsed_cmd  complete parsed command from ws_protocol_parse_req_*
+ * @param response  response struct with uninitialized pointer to msg
+ * @param send  `false` on first run, `true` on second run if `response->csh` was set to true
+ */
+typedef void ws_protocol_res_handler_t(ws_s_protocol_parsed_req_cmd*, ws_s_protocol_res*, bool);
+
+ws_protocol_res_handler_t ws_protocol_res_last_records;
+
+/**
+ * @brief data sender wrapper
+ *
+ * this function should be implemented in the source files of each target
+ * platform, as the send interface will be different on desktop and on the
+ * stm32.
+ *
+ * @param data  pointer to data char array
+ * @param length  length of data array
+ */
+void ws_protocol_send_data(const char* data, unsigned int length);
+
+/** @brief response handlers, called when a command is parsed */
+static ws_protocol_res_handler_t* g_ws_protocol_res_handlers[WS_PROTOCOL_CMD_AMOUNT] = {
+	[WS_PROTOCOL_CMD_LAST_RECORDS] = &ws_protocol_res_last_records,
+};
+
+unsigned short ws_protocol_get_header_size(ws_s_protocol_res* response);
diff --git a/shared/protocol.md b/shared/protocol.md
new file mode 100644
index 0000000..1e52e42
--- /dev/null
+++ b/shared/protocol.md
@@ -0,0 +1,57 @@
+# Protocol spec
+
+This is a brief overview of the protocol specifications that the weather
+station uses to send and receive data between the weather station and qt
+client. This protocol is text-based, and used over a TCP connection. This
+document will only go into detail about the data sent over this connection, not
+requirements about the connection itself.
+
+The protocol is only used in a request-response fashion, so all commands are
+assumed to be sent by the qt client, and responded to by the weather station.
+
+~Functions for generating commands and parsing incoming data are provided by
+the protocol.c and protocol.h files in this folder.~ A server using these files
+should implement every protocol handler function in a seperate c file, along
+with a data sending function that is also used internally.
+
+- LF for newline instead of CRLF
+- Commands are single-line
+- Spaces used for separating command arguments
+- Commands with malformed data are discarded and return error
+- Response consist of `ok` or `error`, a comma, and the byte length of the
+  remaining response (if any)
+- Numbers are sent as hexadecimal
+
+## Commands
+
+### `last-records <n> <o>`
+
+Returns the last `n` records with offset `<o>` in csv format. The first line
+has the csv table header, with the fields `id`, `temperature`, `humidity`, and
+`atmospheric_pressure`. The rest of the response consists of 1 record per line.
+The amount of records is limited to the amount of valid records in the backlog
+buffer. When the amount of returned records is 0, the response consists of the
+csv header, but without any following records.
+
+Offset `<o>` is a positive integer, representing the starting point for the
+most recent record that is returned, this will get subtracted from the id of
+the most recent record. E.g. if the last record has id `00f0`, and a request is
+sent with parameters `n=3` and `o=5`, the records with id's `00eb`, `00ea`, and
+`00e9` will be returned.
+
+## Example transaction
+
+In the following example, newlines are indicated by `<0a>`, request by lines
+starting with `<`, and response by lines starting with `>`.
+
+```
+< last-records 5 0<0a>
+> ok,73<0a>
+> id,temperature,humidity,atmospheric_pressure<0a>
+> 10dc,2f,c5,7f<0a>
+> 10dd,30,c6,7f<0a>
+> 10de,31,c7,7f<0a>
+> 10df,35,ca,7e<0a>
+> 10e0,34,c9,7e<0a>
+```
+
diff --git a/shared/shared.mk b/shared/shared.mk
new file mode 100644
index 0000000..f9586ff
--- /dev/null
+++ b/shared/shared.mk
@@ -0,0 +1 @@
+OBJS += $(patsubst %.c,%-stm.o, $(wildcard ../shared/*.c))
diff --git a/shared/util.c b/shared/util.c
new file mode 100644
index 0000000..ea972b0
--- /dev/null
+++ b/shared/util.c
@@ -0,0 +1,7 @@
+#include "util.h"
+
+unsigned int ws_log16(unsigned int x) {
+    unsigned int l = 0;
+    while (x >>= 4) ++l; // bitshift right by 4 until x == 0
+    return l;
+}
+\ No newline at end of file
diff --git a/shared/util.h b/shared/util.h
new file mode 100644
index 0000000..94a3dfe
--- /dev/null
+++ b/shared/util.h
@@ -0,0 +1,6 @@
+#pragma once
+
+#define WS_MIN(a, b) (((a) < (b)) ? (a) : (b))
+#define WS_MAX(a, b) (((a) > (b)) ? (a) : (b))
+
+unsigned int ws_log16(unsigned int x);