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sredird.c
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sredird.c
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/*
sredird: RFC 2217 compliant serial port redirector
Version 2.2.1, 20 February 2004
Copyright (C) 1999 - 2003 InfoTecna s.r.l.
Copyright (C) 2001, 2002 Trustees of Columbia University
in the City of New York
Copyright (C) 2020-2021 Michael Santos <[email protected]>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <sys/types.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <poll.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdnoreturn.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <syslog.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>
#include "restrict_process.h"
/* Version id */
#define VersionId "2.2.1"
#define SRedirdVersionId "Version " VersionId ", 20 February 2004"
/* Maximum length of temporary strings */
#define TmpStrLen 255
/* Buffer size */
#define BufferSize 2048
/* Base Telnet protocol constants (STD 8) */
#define TNSE 240
#define TNNOP 241
#define TNSB 250
#define TNWILL 251
#define TNWONT 252
#define TNDO 253
#define TNDONT 254
#define TNIAC 255
/* Base Telnet protocol options constants (STD 27, STD 28, STD 29) */
#define TN_TRANSMIT_BINARY 0
#define TN_ECHO 1
#define TN_SUPPRESS_GO_AHEAD 3
/* Base Telnet Com Port Control (CPC) protocol constants (RFC 2217) */
#define TNCOM_PORT_OPTION 44
/* CPC Client to Access Server constants */
#define TNCAS_SIGNATURE 0
#define TNCAS_SET_BAUDRATE 1
#define TNCAS_SET_DATASIZE 2
#define TNCAS_SET_PARITY 3
#define TNCAS_SET_STOPSIZE 4
#define TNCAS_SET_CONTROL 5
#define TNCAS_NOTIFY_LINESTATE 6
#define TNCAS_NOTIFY_MODEMSTATE 7
#define TNCAS_FLOWCONTROL_SUSPEND 8
#define TNCAS_FLOWCONTROL_RESUME 9
#define TNCAS_SET_LINESTATE_MASK 10
#define TNCAS_SET_MODEMSTATE_MASK 11
#define TNCAS_PURGE_DATA 12
/* CPC Access Server to Client constants */
#define TNASC_SIGNATURE 100
#define TNASC_SET_BAUDRATE 101
#define TNASC_SET_DATASIZE 102
#define TNASC_SET_PARITY 103
#define TNASC_SET_STOPSIZE 104
#define TNASC_SET_CONTROL 105
#define TNASC_NOTIFY_LINESTATE 106
#define TNASC_NOTIFY_MODEMSTATE 107
#define TNASC_FLOWCONTROL_SUSPEND 108
#define TNASC_FLOWCONTROL_RESUME 109
#define TNASC_SET_LINESTATE_MASK 110
#define TNASC_SET_MODEMSTATE_MASK 111
#define TNASC_PURGE_DATA 112
/* Modem state effective change mask */
#define ModemStateECMask 255
#define LineStateECMask 255
/* Default modem state polling in milliseconds (100 msec should be enough) */
#define ModemStatePolling 100
#define COUNT(_array) (sizeof(_array) / sizeof(_array[0]))
#define DEVICE_FILENO 2
/* Standard boolean definition */
typedef enum { False, True } Boolean;
/* Cisco IOS bug compatibility */
static Boolean CiscoIOSCompatible = False;
/* Buffer structure */
typedef struct {
unsigned char Buffer[BufferSize];
unsigned int RdPos;
unsigned int WrPos;
} BufferType;
/* Complete device file pathname */
static const char *DeviceName;
/* Device file descriptor */
static int DeviceFd = -1;
/* Com Port Control enabled flag */
static Boolean TCPCEnabled = False;
/* True after retrieving the initial settings from the serial port */
static Boolean InitPortRetrieved = False;
/* Initial serial port settings */
static struct termios InitialPortSettings;
/* Maximum log level to log in the system log */
static int MaxLogLevel = LOG_DEBUG + 1;
/* Status enumeration for IAC escaping and interpretation */
typedef enum { IACNormal, IACReceived, IACComReceiving } IACState;
/* Effective status for IAC escaping and interpretation */
static IACState IACEscape = IACNormal;
/* Same as above during signature reception */
static IACState IACSigEscape;
/* Current IAC command begin received */
static unsigned char IACCommand[TmpStrLen];
/* Position of insertion into IACCommand[] */
static size_t IACPos;
/* Modem state mask set by the client */
static unsigned char ModemStateMask = 255;
/* Line state mask set by the client */
static unsigned char LineStateMask = 0;
#ifdef COMMENT
/* Current status of the line control lines */
static unsigned char LineState = 0;
#endif
/* Current status of the modem control lines */
static unsigned char ModemState = 0;
/* Break state flag */
static Boolean BreakSignaled = False;
/* Input flow control flag */
static Boolean InputFlow = True;
/* Telnet State Machine */
static struct _tnstate {
unsigned int sent_will : 1;
unsigned int sent_do : 1;
unsigned int sent_wont : 1;
unsigned int sent_dont : 1;
unsigned int is_will : 1;
unsigned int is_do : 1;
} tnstate[256];
/* Function prototypes */
/* initialize Telnet State Machine */
void InitTelnetStateMachine(void);
/* Initialize a buffer for operation */
void InitBuffer(BufferType *B);
/* Check if the buffer is empty */
static Boolean IsBufferEmpty(BufferType *B);
/* Check if the buffer is full */
static Boolean IsBufferFull(BufferType *B);
/* Add a byte to a buffer */
void AddToBuffer(BufferType *B, unsigned char C);
/* Push a byte to a buffer */
void PushToBuffer(BufferType *B, unsigned char C);
/* Get a byte from a buffer */
unsigned char GetFromBuffer(BufferType *B);
/* Generic log function with log level control. Uses the same log levels
of the syslog(3) system call */
void LogMsg(int LogLevel, const char *const fmt, ...);
/* Function executed when the program exits */
static noreturn void ExitFunction(void);
/* Function called on many signals */
static noreturn void SignalFunction(int unused);
/* Function called on break signal */
static noreturn void BreakFunction(int unused);
/* Retrieves the port speed from PortFd */
unsigned long int GetPortSpeed(int PortFd);
/* Retrieves the data size from PortFd */
unsigned char GetPortDataSize(int PortFd);
/* Retrieves the parity settings from PortFd */
unsigned char GetPortParity(int PortFd);
/* Retrieves the stop bits size from PortFd */
unsigned char GetPortStopSize(int PortFd);
/* Retrieves the flow control status, including DTR and RTS status,
from PortFd */
unsigned char GetPortFlowControl(int PortFd, unsigned char Which);
/* Return the status of the modem control lines (DCD, CTS, DSR, RNG) */
unsigned char GetModemState(int PortFd, unsigned char PMState);
/* Set the serial port data size */
void SetPortDataSize(int PortFd, unsigned char DataSize);
/* Set the serial port parity */
void SetPortParity(int PortFd, unsigned char Parity);
/* Set the serial port stop bits size */
void SetPortStopSize(int PortFd, unsigned char StopSize);
/* Set the port flow control and DTR and RTS status */
void SetPortFlowControl(int PortFd, unsigned char How);
/* Set the serial port speed */
void SetPortSpeed(int PortFd, unsigned long BaudRate);
/* Send the signature Sig to the client */
void SendSignature(BufferType *B, char *Sig);
/* Write a char to SockFd performing IAC escaping */
void EscWriteChar(BufferType *B, unsigned char C);
/* Redirect char C to PortFd checking for IAC escape sequences */
void EscRedirectChar(BufferType *SockB, BufferType *DevB, int PortFd,
unsigned char C);
/* Send the specific telnet option to SockFd using Command as command */
void SendTelnetOption(BufferType *B, unsigned char Command, char Option);
/* Send a string to SockFd performing IAC escaping */
void SendStr(BufferType *B, char *Str);
/* Send the baud rate BR to SockFd */
void SendBaudRate(BufferType *B, unsigned long int BR);
/* Send the flow control command Command */
void SendCPCFlowCommand(BufferType *B, unsigned char Command);
/* Send the CPC command Command using Parm as parameter */
void SendCPCByteCommand(BufferType *B, unsigned char Command,
unsigned char Parm);
/* Handling of COM Port Control specific commands */
void HandleCPCCommand(BufferType *B, int PortFd, unsigned char *Command,
size_t CSize);
/* Common telnet IAC commands handling */
void HandleIACCommand(BufferType *B, int PortFd, unsigned char *Command,
size_t CSize);
/* Write a buffer to SockFd with IAC escaping */
void EscWriteBuffer(BufferType *B, unsigned char *Buffer, unsigned int BSize);
/* Usage */
void Usage(void);
static const struct option long_options[] = {
{"timeout", required_argument, NULL, 't'},
{"cisco-compatibility", no_argument, NULL, 'i'},
{"help", no_argument, NULL, 'h'},
{NULL, 0, NULL, 0}};
/* initialize Telnet State Machine */
void InitTelnetStateMachine(void) {
int i;
for (i = 0; i < 256; i++) {
tnstate[i].sent_do = 0;
tnstate[i].sent_will = 0;
tnstate[i].sent_wont = 0;
tnstate[i].sent_dont = 0;
tnstate[i].is_do = 0;
tnstate[i].is_will = 0;
}
}
/* Initialize a buffer for operation */
void InitBuffer(BufferType *B) {
/* Set the initial buffer positions */
B->RdPos = 0;
B->WrPos = 0;
}
/* Check if the buffer is empty */
Boolean IsBufferEmpty(BufferType *B) { return ((Boolean)B->RdPos == B->WrPos); }
/* Check if the buffer is full */
Boolean IsBufferFull(BufferType *B) {
/* We consider the buffer to be filled when there are 100 bytes left
This is so even a full buffer can safely have escaped characters
added to it.
*/
return ((Boolean)B->WrPos == (B->RdPos + BufferSize - 101) % BufferSize);
}
/* Add a byte to a buffer */
void AddToBuffer(BufferType *B, unsigned char C) {
B->Buffer[B->WrPos] = C;
B->WrPos = (B->WrPos + 1) % BufferSize;
}
void PushToBuffer(BufferType *B, unsigned char C) {
if (B->RdPos > 0)
B->RdPos--;
else
B->RdPos = BufferSize - 1;
B->Buffer[B->RdPos] = C;
}
/* Get a byte from a buffer */
unsigned char GetFromBuffer(BufferType *B) {
unsigned char C = B->Buffer[B->RdPos];
B->RdPos = (B->RdPos + 1) % BufferSize;
return C;
}
/* Generic log function with log level control. Uses the same log levels
of the syslog(3) system call */
void LogMsg(int LogLevel, const char *const fmt, ...) {
va_list ap;
if (LogLevel <= MaxLogLevel) {
(void)fprintf(stderr, "%s: ", DeviceName);
va_start(ap, fmt);
(void)vfprintf(stderr, fmt, ap);
va_end(ap);
(void)fprintf(stderr, "\n");
}
}
/* Function executed when the program exits */
static noreturn void ExitFunction(void) {
const char *message = "SRedird stopped.\n";
/* Restores initial port settings */
if (DeviceFd > -1) {
if (InitPortRetrieved == True)
tcsetattr(DeviceFd, TCSANOW, &InitialPortSettings);
}
/* Program termination notification */
if (MaxLogLevel >= LOG_NOTICE) {
/* warning: ignoring return value of ‘write’, declared with attribute
* warn_unused_result [-Wunused-result] */
if (write(STDERR_FILENO, message, strlen(message)) == -1) {
}
}
_exit(0);
}
/* Function called on many signals */
static noreturn void SignalFunction(int unused) {
(void)unused;
/* Same as the exit function */
ExitFunction();
}
/* Function called on break signal */
/* Unimplemented yet */
static noreturn void BreakFunction(int unused) {
#ifndef COMMENT
(void)unused;
/* Same as the exit function */
ExitFunction();
#else /* COMMENT */
unsigned char LineState;
if (BreakSignaled == True) {
BreakSignaled = False;
LineState = 0;
} else {
BreakSignaled = True;
LineState = 16;
}
/* Notify client of break change */
if ((LineStateMask & (unsigned char)16) != 0) {
LogMsg(LOG_DEBUG, "Notifying break change.");
SendCPCByteCommand(&ToNetBuf, TNASC_NOTIFY_LINESTATE, LineState);
}
#endif /* COMMENT */
}
/* Retrieves the port speed from PortFd */
unsigned long int GetPortSpeed(int PortFd) {
struct termios PortSettings;
speed_t Speed;
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
Speed = cfgetospeed(&PortSettings);
switch (Speed) {
case B50:
return 50UL;
case B75:
return 75UL;
case B110:
return 110UL;
case B134:
return 134UL;
case B150:
return 150UL;
case B200:
return 200UL;
case B300:
return 300UL;
case B600:
return 600UL;
case B1200:
return 1200UL;
case B1800:
return 1800UL;
case B2400:
return 2400UL;
case B4800:
return 4800UL;
case B9600:
return 9600UL;
case B19200:
return 19200UL;
case B38400:
return 38400UL;
case B57600:
return 57600UL;
case B115200:
return 115200UL;
case B230400:
return 230400UL;
#ifdef B460800
case B460800:
return 460800UL;
#endif
default:
return 0UL;
}
}
/* Retrieves the data size from PortFd */
unsigned char GetPortDataSize(int PortFd) {
struct termios PortSettings;
tcflag_t DataSize;
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgettattr");
DataSize = PortSettings.c_cflag & CSIZE;
switch (DataSize) {
case CS5:
return 5;
case CS6:
return 6;
case CS7:
return 7;
case CS8:
return 8;
default:
return 0;
}
}
/* Retrieves the parity settings from PortFd */
unsigned char GetPortParity(int PortFd) {
struct termios PortSettings;
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
if ((PortSettings.c_cflag & PARENB) == 0)
return 1;
if ((PortSettings.c_cflag & PARENB) != 0 &&
(PortSettings.c_cflag & PARODD) != 0)
return 2;
return 3;
}
/* Retrieves the stop bits size from PortFd */
unsigned char GetPortStopSize(int PortFd) {
struct termios PortSettings;
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
if ((PortSettings.c_cflag & CSTOPB) == 0)
return 1;
return 2;
}
/* Retrieves the flow control status, including DTR and RTS status,
from PortFd */
unsigned char GetPortFlowControl(int PortFd, unsigned char Which) {
struct termios PortSettings;
int MLines;
/* Gets the basic informations from the port */
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
if (ioctl(PortFd, TIOCMGET, &MLines) < 0)
err(EXIT_FAILURE, "ioctl(TIOCMGET)");
/* Check which kind of information is requested */
switch (Which) {
/* Com Port Flow Control Setting (outbound/both) */
case 0:
if (PortSettings.c_iflag & IXON)
return 2;
if (PortSettings.c_cflag & CRTSCTS)
return 3;
return 1;
/* BREAK State */
case 4:
if (BreakSignaled == True)
return 5;
return 6;
/* DTR Signal State */
case 7:
if (MLines & TIOCM_DTR)
return 8;
return 9;
/* RTS Signal State */
case 10:
if (MLines & TIOCM_RTS)
return 11;
return 12;
/* Com Port Flow Control Setting (inbound) */
case 13:
if (PortSettings.c_iflag & IXOFF)
return 15;
if (PortSettings.c_cflag & CRTSCTS)
return 16;
return 14;
default:
if (PortSettings.c_iflag & IXON)
return 2;
if (PortSettings.c_cflag & CRTSCTS)
return 3;
return 1;
}
}
/* Return the status of the modem control lines (DCD, CTS, DSR, RNG) */
unsigned char GetModemState(int PortFd, unsigned char PMState) {
int MLines;
unsigned char MState = 0;
if (ioctl(PortFd, TIOCMGET, &MLines) < 0)
err(EXIT_FAILURE, "ioctl(TIOCMGET)");
if ((MLines & TIOCM_CAR) != 0)
MState += 128;
if ((MLines & TIOCM_RNG) != 0)
MState += 64;
if ((MLines & TIOCM_DSR) != 0)
MState += 32;
if ((MLines & TIOCM_CTS) != 0)
MState += 16;
if ((MState & 128) != (PMState & 128))
MState += 8;
if ((MState & 64) != (PMState & 64))
MState += 4;
if ((MState & 32) != (PMState & 32))
MState += 2;
if ((MState & 16) != (PMState & 16))
MState += 1;
return MState;
}
/* Set the serial port data size */
void SetPortDataSize(int PortFd, unsigned char DataSize) {
struct termios PortSettings;
tcflag_t PDataSize;
switch (DataSize) {
case 5:
PDataSize = CS5;
break;
case 6:
PDataSize = CS6;
break;
case 7:
PDataSize = CS7;
break;
case 8:
PDataSize = CS8;
break;
default:
PDataSize = CS8;
break;
}
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
PortSettings.c_cflag &= ~CSIZE;
PortSettings.c_cflag |= PDataSize & CSIZE;
if (tcsetattr(PortFd, TCSADRAIN, &PortSettings) < 0)
err(EXIT_FAILURE, "tcsetattr");
}
/* Set the serial port parity */
void SetPortParity(int PortFd, unsigned char Parity) {
struct termios PortSettings;
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
switch (Parity) {
case 1:
PortSettings.c_cflag = PortSettings.c_cflag & ~PARENB;
break;
case 2:
PortSettings.c_cflag = PortSettings.c_cflag | PARENB | PARODD;
break;
case 3:
PortSettings.c_cflag = (PortSettings.c_cflag | PARENB) & ~PARODD;
break;
/* There's no support for MARK and SPACE parity so sets no parity */
default:
LogMsg(LOG_WARNING, "Requested unsupported parity, set to no parity.");
PortSettings.c_cflag = PortSettings.c_cflag & ~PARENB;
break;
}
if (tcsetattr(PortFd, TCSADRAIN, &PortSettings) < 0)
err(EXIT_FAILURE, "tcsetattr");
}
/* Set the serial port stop bits size */
void SetPortStopSize(int PortFd, unsigned char StopSize) {
struct termios PortSettings;
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
switch (StopSize) {
case 1:
PortSettings.c_cflag = PortSettings.c_cflag & ~CSTOPB;
break;
case 2:
PortSettings.c_cflag = PortSettings.c_cflag | CSTOPB;
break;
case 3:
PortSettings.c_cflag = PortSettings.c_cflag & ~CSTOPB;
LogMsg(LOG_WARNING,
"Requested unsupported 1.5 bits stop size, set to 1 bit stop size.");
break;
default:
PortSettings.c_cflag = PortSettings.c_cflag & ~CSTOPB;
break;
}
if (tcsetattr(PortFd, TCSADRAIN, &PortSettings) < 0)
err(EXIT_FAILURE, "tcsetattr");
}
/* Set the port flow control and DTR and RTS status */
void SetPortFlowControl(int PortFd, unsigned char How) {
struct termios PortSettings;
int MLines;
/* Gets the base status from the port */
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
if (ioctl(PortFd, TIOCMGET, &MLines) < 0)
err(EXIT_FAILURE, "ioctl(TIOCMGET)");
/* Check which settings to change */
switch (How) {
/* No Flow Control (outbound/both) */
case 1:
PortSettings.c_iflag = PortSettings.c_iflag & ~IXON;
PortSettings.c_iflag = PortSettings.c_iflag & ~IXOFF;
PortSettings.c_cflag = PortSettings.c_cflag & ~CRTSCTS;
break;
/* XON/XOFF Flow Control (outbound/both) */
case 2:
PortSettings.c_iflag = PortSettings.c_iflag | IXON;
PortSettings.c_iflag = PortSettings.c_iflag | IXOFF;
PortSettings.c_cflag = PortSettings.c_cflag & ~CRTSCTS;
break;
/* HARDWARE Flow Control (outbound/both) */
case 3:
PortSettings.c_iflag = PortSettings.c_iflag & ~IXON;
PortSettings.c_iflag = PortSettings.c_iflag & ~IXOFF;
PortSettings.c_cflag = PortSettings.c_cflag | CRTSCTS;
break;
/* BREAK State ON */
case 5:
if (tcsendbreak(PortFd, 1) < 0)
err(EXIT_FAILURE, "tcsendbreak");
BreakSignaled = True;
break;
/* BREAK State OFF */
case 6:
/* Should not send another break */
/* tcsendbreak(PortFd,0); */
BreakSignaled = False;
break;
/* DTR Signal State ON */
case 8:
MLines = MLines | TIOCM_DTR;
break;
/* DTR Signal State OFF */
case 9:
MLines = MLines & ~TIOCM_DTR;
break;
/* RTS Signal State ON */
case 11:
MLines = MLines | TIOCM_RTS;
break;
/* RTS Signal State OFF */
case 12:
MLines = MLines & ~TIOCM_RTS;
break;
/* INBOUND FLOW CONTROL is ignored */
/* No Flow Control (inbound) */
case 14:
/* XON/XOFF Flow Control (inbound) */
case 15:
/* HARDWARE Flow Control (inbound) */
case 16:
LogMsg(LOG_WARNING, "Inbound flow control ignored.");
break;
default:
LogMsg(LOG_WARNING, "Requested unsupported flow control.");
break;
}
if (tcsetattr(PortFd, TCSADRAIN, &PortSettings) < 0)
err(EXIT_FAILURE, "tcsetattr");
if (ioctl(PortFd, TIOCMSET, &MLines) < 0)
err(EXIT_FAILURE, "ioctl(TIOCMSET)");
}
/* Set the serial port speed */
void SetPortSpeed(int PortFd, unsigned long BaudRate) {
struct termios PortSettings;
speed_t Speed;
switch (BaudRate) {
case 50UL:
Speed = B50;
break;
case 75UL:
Speed = B75;
break;
case 110UL:
Speed = B110;
break;
case 134UL:
Speed = B134;
break;
case 150UL:
Speed = B150;
break;
case 200UL:
Speed = B200;
break;
case 300UL:
Speed = B300;
break;
case 600UL:
Speed = B600;
break;
case 1200UL:
Speed = B1200;
break;
case 1800UL:
Speed = B1800;
break;
case 2400UL:
Speed = B2400;
break;
case 4800UL:
Speed = B4800;
break;
case 9600UL:
Speed = B9600;
break;
case 19200UL:
Speed = B19200;
break;
case 38400UL:
Speed = B38400;
break;
case 57600UL:
Speed = B57600;
break;
case 115200UL:
Speed = B115200;
break;
case 230400UL:
Speed = B230400;
break;
#ifdef B460800
case 460800UL:
Speed = B460800;
break;
#endif
default:
LogMsg(LOG_WARNING, "Unknown baud rate requested, setting to 9600.");
Speed = B9600;
break;
}
if (tcgetattr(PortFd, &PortSettings) < 0)
err(EXIT_FAILURE, "tcgetattr");
if (cfsetospeed(&PortSettings, Speed) < 0)
err(EXIT_FAILURE, "cfsetospeed");
if (cfsetispeed(&PortSettings, Speed) < 0)
err(EXIT_FAILURE, "cfsetispeed");
if (tcsetattr(PortFd, TCSADRAIN, &PortSettings) < 0)
err(EXIT_FAILURE, "tcsetattr");
}
/* Send the signature Sig to the client */
void SendSignature(BufferType *B, char *Sig) {
AddToBuffer(B, TNIAC);
AddToBuffer(B, TNSB);
AddToBuffer(B, TNCOM_PORT_OPTION);
AddToBuffer(B, TNASC_SIGNATURE);
SendStr(B, Sig);
AddToBuffer(B, TNIAC);
AddToBuffer(B, TNSE);
}
/* Write a char to socket performing IAC escaping */
void EscWriteChar(BufferType *B, unsigned char C) {
/* Last received byte */
static unsigned char Last = 0;
if (C == TNIAC)
AddToBuffer(B, C);
else if (C != 0x0A && !tnstate[TN_TRANSMIT_BINARY].is_will && Last == 0x0D)
AddToBuffer(B, 0x00);
AddToBuffer(B, C);
/* Set last received byte */
Last = C;
}
/* Redirect char C to Device checking for IAC escape sequences */
void EscRedirectChar(BufferType *SockB, BufferType *DevB, int PortFd,
unsigned char C) {
/* Last received byte */
static unsigned char Last = 0;
/* Check the IAC escape status */
switch (IACEscape) {
/* Normal status */
case IACNormal:
if (C == TNIAC)
IACEscape = IACReceived;
else if (!tnstate[TN_TRANSMIT_BINARY].is_do && C == 0x00 && Last == 0x0D)
/* Swallow the NUL after a CR if not receiving BINARY */
break;
else
AddToBuffer(DevB, C);
break;
/* IAC previously received */
case IACReceived:
if (C == TNIAC) {
AddToBuffer(DevB, C);
IACEscape = IACNormal;
} else {
IACCommand[0] = TNIAC;
IACCommand[1] = C;
IACPos = 2;
IACEscape = IACComReceiving;
IACSigEscape = IACNormal;
}
break;
/* IAC Command reception */
case IACComReceiving:
/* Telnet suboption, could be only CPC */
if (IACCommand[1] == TNSB) {
/* Get the suboption signature */
if (IACPos < 4) {
IACCommand[IACPos] = C;
IACPos++;
} else {
/* Check which suboption we are dealing with */
switch (IACCommand[3]) {
/* Signature, which needs further escaping */
case TNCAS_SIGNATURE:
switch (IACSigEscape) {
case IACNormal:
if (C == TNIAC)
IACSigEscape = IACReceived;
else if (IACPos < TmpStrLen) {
IACCommand[IACPos] = C;
IACPos++;
}
break;
case IACComReceiving:
IACSigEscape = IACNormal;
break;
case IACReceived:
if (C == TNIAC) {
if (IACPos < TmpStrLen) {
IACCommand[IACPos] = C;
IACPos++;
}
IACSigEscape = IACNormal;
} else {
if (IACPos < TmpStrLen) {
IACCommand[IACPos] = TNIAC;
IACPos++;
}
if (IACPos < TmpStrLen) {
IACCommand[IACPos] = C;
IACPos++;
}
HandleIACCommand(SockB, PortFd, IACCommand, IACPos);
IACEscape = IACNormal;
}
break;
}
break;
/* Set baudrate */
case TNCAS_SET_BAUDRATE:
IACCommand[IACPos] = C;
IACPos++;
if (IACPos == 10) {
HandleIACCommand(SockB, PortFd, IACCommand, IACPos);
IACEscape = IACNormal;
}
break;
/* Flow control command */
case TNCAS_FLOWCONTROL_SUSPEND:
case TNCAS_FLOWCONTROL_RESUME:
IACCommand[IACPos] = C;