Serial driver and basic KISS interface implemented

.gitignore

@@ -1,3 +1,4 @@
+tncattach
 # Prerequisites
 *.d
 

KISS.c

@@ -0,0 +1,69 @@
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "KISS.h"
+#include "Serial.h"
+
+int frame_len;
+bool IN_FRAME;
+bool ESCAPE;
+
+uint8_t kiss_command = CMD_UNKNOWN;
+uint8_t frame_buffer[MAX_PAYLOAD];
+uint8_t write_buffer[MAX_PAYLOAD*2+3];
+
+void kiss_frame_received(int frame_len) {
+	
+}
+
+void kiss_serial_read(uint8_t sbyte) {
+	if (IN_FRAME && sbyte == FEND && kiss_command == CMD_DATA) {
+	    IN_FRAME = false;
+	    kiss_frame_received(frame_len);
+	} else if (sbyte == FEND) {
+	    IN_FRAME = true;
+	    kiss_command = CMD_UNKNOWN;
+	    frame_len = 0;
+	} else if (IN_FRAME && frame_len < MAX_PAYLOAD) {
+	    // Have a look at the command byte first
+	    if (frame_len == 0 && kiss_command == CMD_UNKNOWN) {
+	    	// Strip of port nibble
+	        kiss_command = sbyte & 0x0F;
+	    } else if (kiss_command == CMD_DATA) {
+	        if (sbyte == FESC) {
+	            ESCAPE = true;
+	        } else {
+	            if (ESCAPE) {
+	                if (sbyte == TFEND) sbyte = FEND;
+	                if (sbyte == TFESC) sbyte = FESC;
+	                ESCAPE = false;
+	            }
+
+	            if (frame_len < MAX_PAYLOAD) {
+	            	frame_buffer[frame_len++] = sbyte;
+	            }
+	        }
+	    }
+	}
+}
+
+int kiss_write_frame(int serial_port, uint8_t* buffer, int frame_len) {
+	int write_len = 0;
+	write_buffer[write_len++] = FEND;
+	write_buffer[write_len++] = CMD_DATA;
+	for (int i = 0; i < frame_len; i++) {
+		uint8_t byte = buffer[i];
+		if (byte == FEND) {
+			write_buffer[write_len++] = FESC;
+			write_buffer[write_len++] = TFEND;
+		} else if (byte == FESC) {
+			write_buffer[write_len++] = FESC;
+			write_buffer[write_len++] = TFESC;
+		} else {
+			write_buffer[write_len++] = byte;
+		}
+	}
+	write_buffer[write_len++] = FEND;
+
+	return write(serial_port, write_buffer, write_len);
+}

KISS.h

@@ -10,4 +10,9 @@
 #define CMD_SLOTTIME 0x03
 #define CMD_TXTAIL 0x04
 #define CMD_FULLDUPLEX 0x05
-#define CMD_SETHARDWARE 0x06
+#define CMD_SETHARDWARE 0x06
+
+#define MAX_PAYLOAD 1522
+
+void kiss_serial_read(uint8_t sbyte);
+int kiss_write_frame(int serial_port, uint8_t* buffer, int frame_len);

README.md

@@ -0,0 +1,3 @@
+TNC Attach
+==========
+Attach KISS TNC devices as network interfaces in Linux and macOS.

Serial.c

@@ -0,0 +1,168 @@
+#include "Serial.h"
+
+int open_port(char* port) {
+	int fd;
+	fd = open(port, O_RDWR | O_NOCTTY | O_SYNC | O_NDELAY);
+
+	if (fd == -1) {
+		perror("The serial port could not be opened");
+	} else {
+		fcntl(fd, F_SETFL, 0);
+	}
+
+	return fd;
+}
+
+int close_port(int fd) {
+	return close(fd);
+}
+
+void set_speed(void *tty_s, int speed) {
+	cfsetospeed(tty_s, speed);
+	cfsetispeed(tty_s, speed);
+}
+
+bool setup_port(int fd, int speed) {
+	struct termios tty;
+	if (tcgetattr(fd, &tty) != 0) {
+		perror("Error setting port speed, could not read port parameters");
+		return false;
+	}
+
+	switch (speed) {
+		case 0:
+			set_speed(&tty, B0);
+			break;
+		case 50:
+			set_speed(&tty, B50);
+			break;
+		case 75:
+			set_speed(&tty, B75);
+			break;
+		case 110:
+			set_speed(&tty, B110);
+			break;
+		case 134:
+			set_speed(&tty, B134);
+			break;
+		case 150:
+			set_speed(&tty, B150);
+			break;
+		case 200:
+			set_speed(&tty, B200);
+			break;
+		case 300:
+			set_speed(&tty, B300);
+			break;
+		case 600:
+			set_speed(&tty, B600);
+			break;
+		case 1200:
+			set_speed(&tty, B1200);
+			break;
+		case 2400:
+			set_speed(&tty, B2400);
+			break;
+		case 4800:
+			set_speed(&tty, B4800);
+			break;
+		case 9600:
+			set_speed(&tty, B9600);
+			break;
+		case 19200:
+			set_speed(&tty, B19200);
+			break;
+		case 38400:
+			set_speed(&tty, B38400);
+			break;
+		case 57600:
+			set_speed(&tty, B57600);
+			break;
+		case 115200:
+			set_speed(&tty, B115200);
+			break;
+		case 230400:
+			set_speed(&tty, B230400);
+			break;
+		default:
+			printf("Error: Invalid port speed %d specified", speed);
+			return false;
+	}
+
+	// Set 8-bit characters, no parity, one stop bit
+	tty.c_cflag |= CS8;
+	tty.c_cflag &= ~PARENB;
+	tty.c_cflag &= ~CSTOPB;
+
+	// Disable hardware flow control
+	tty.c_cflag &= ~CRTSCTS;
+
+	// Enable reading and ignore modem
+	// control lines
+	tty.c_cflag |= CREAD | CLOCAL;
+
+	// Disable canonical mode, echo
+	// and signal characters.
+	tty.c_lflag &= ~ICANON;
+	tty.c_lflag &= ~ECHO;
+	tty.c_lflag &= ~ECHOE;
+	tty.c_lflag &= ~ECHONL;
+	tty.c_lflag &= ~ISIG;
+
+	// Disable processing of input,
+	// just pass the raw data.
+	tty.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL);
+
+	// Disable XON/XOFF software flow control.
+	tty.c_iflag &= ~(IXON | IXOFF | IXANY);
+
+	// Disable processing output bytes
+	// and new line conversions
+	tty.c_oflag &= ~OPOST;
+	tty.c_oflag &= ~ONLCR;
+
+	// Block forever until at least one byte is read.
+	tty.c_cc[VMIN]   = 1;
+	tty.c_cc[VTIME]  = 0;
+
+	// TODO: Check these
+	// Prevent conversion of tabs to spaces (NOT PRESENT IN LINUX)
+	// tty.c_oflag &= ~OXTABS;
+	// Prevent removal of C-d chars (0x004) in output (NOT PRESENT IN LINUX)
+	// tty.c_oflag &= ~ONOEOT;
+
+	if (tcsetattr(fd, TCSANOW, &tty) != 0) {
+		perror("Could not configure serial port parameters");
+		return false;
+	} else {
+		return true;
+	}
+}
+
+bool set_port_blocking(int fd, bool should_block) {
+	struct termios tty;
+	memset(&tty, 0, sizeof tty);
+
+	if (tcgetattr(fd, &tty) != 0) {
+		perror("Error configuring port blocking behaviour, could not read port parameters");
+		return false;
+	} else {
+		// TODO: Implement this correctly
+		if (should_block) {
+			// Block forever until at least one byte is read.
+			tty.c_cc[VMIN]   = 1;
+			tty.c_cc[VTIME]  = 0;
+		} else {
+			// Never block, always return immediately with
+			// whatever is available.
+			tty.c_cc[VMIN]   = 0;
+			tty.c_cc[VTIME]  = 0;
+		}
+		if (tcsetattr(fd, TCSANOW, &tty) != 0) {
+			perror("Could not set port parameters while configuring blocking behaviour");
+			return false;
+		} else {
+			return true;
+		}
+	}
+}

Serial.h

@@ -0,0 +1,12 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <termios.h>
+
+int open_port(char* port);
+int close_port(int fd);
+bool setup_port(int fs, int speed);
+bool set_port_blocking(int fd, bool should_block);

TAP.c

@@ -0,0 +1,3 @@
+#include "TAP.h"
+
+char tap_name[IFNAMSIZ];

makefile

@@ -1,10 +1,11 @@
 .DEFAULT_GOAL := all
-.PHONY: all clean install
+.PHONY: all clean install tncattach
 
 compiler = gcc
 flags = -lm
 
 all: tncattach
+rebuild: clean all
 
 clean:
 	@echo "Cleaning tncattach build..."
@@ -13,7 +14,7 @@ clean:
 tncattach:
 	@echo "Making tncattach..."
 	@echo "Compiling with: ${compiler}"
-	${compiler} ${flags} tncattach.c -o tncattach
+	${compiler} ${flags} tncattach.c Serial.c KISS.c TAP.c -o tncattach -Wall
 
 install: all
 	@echo "Installing tncattach..."

tncattach.c

@@ -1,5 +1,45 @@
+#include <stdlib.h>
+#include <stdbool.h>
+#include <signal.h>
+#include "Serial.h"
 #include "KISS.h"
+#include "TAP.h"
+
+#define SERIAL_BUFFER_SIZE 512
+
+int attached_port;
+uint8_t serial_buffer[512];
+
+void signal_handler(int signal) {
+	printf("\r\nClosing serial port...\r\n");
+	close_port(attached_port);
+	exit(0);
+}
+
+void read_loop(tnc) {
+	bool should_continue = true;
+	while (should_continue) {
+		int len = read(attached_port, serial_buffer, sizeof(serial_buffer));
+		if (len > 0) {
+			for (int i = 0; i < len; i++) {
+				kiss_serial_read(serial_buffer[i]);
+			}
+		} else {
+			printf("Error: Could not read from serial port, exiting now\r\n");
+			close_port(attached_port);
+			exit(1);
+		}
+	}
+}
 
 int main() {
+	signal(SIGINT, signal_handler);
+
+	attached_port = open_port("/dev/tty.usbserial-");
+	if (setup_port(attached_port, 115200)) {
+		printf("Port open\r\n");
+		read_loop(attached_port);
+	}
+	
 	return 0;
 }