#!/bin/bash

# Rules for chat scripts
# No comments allowed at the end of AT+CGDCONT in chat script
# The last AT+CGDCONT= must use the same context as the dialer.
# If desired, The AT+CGDCONT may be prefixed by #MT[[:space:]]+
# Example:
#MT AT+CGDCONT="IPV6","data","192.168.2.1",0,1,"EXTRA"
#
# If you do not use a comment, the entire AT+CGDCONT command
# must be surrounded by apostrophes.  This command will be executed
# twice, once in the chat wrapper, and a 2nd time in the chat
# itself.
#
# The space after "#MT" may be any number including tabs.
# If #MT AT+CGDCONT= is found, only the last one is chosen.
# Any uncommented AT+CGDCONT= is then ignored.
# If there are not #MT AT+CGDCONT= lines, then any line without
# a comment chararacter before AT+CGDONT= is accepted, but only the
# last one in the file.
#
# On entry to this script, file descriptor 0 is the modem.
# For ppp to work, stty must work on file descriptor 0.
# If stty fails, so will ppp.

NAME=chat_wrapper
CONFIG=/etc/default/${NAME}
CHAT_WRAPPER_RECURSION=/run/chat_wrapper_recursion
RQCMD="/usr/bin/radio-query ${RADIOOPTION}"
function finish
{
        ${LOG} "Launch:" "$@"
        exec "$@"
        # NOTREACHED
}

# This function is used to determine if the modem and serial driver
# are working.  In testing, the driver has gotten into states where
# stty fails.  Before the chat script is started, the ioctl TCGETS is
# performed, and will fail if the driver is hung.  This same function
# is called by stty.  The modem port used by pppd is STDIN.  Cases
# have been observed on the H5 where radio-cmd works, but stty does
# not, resulting in pppd failing. When this happens, radio-reset is
# the best thing to try.
function sanity
{
  id="^[0-9][0-9][0-9][0-9][0-9][0-9]"
  if ! log=$(stty 2>&1) || ! [[ $($RQCMD --iccid) =~ $id ]] ; then
    ${LOG} "Modem has response issues, so see if we can try again"
    if ((${#log} > 0)); then
        ${LOG} "stty error: $(log)"
    fi
    array=( )
    # our parent is PPID, which is pppd.  Get the pppd
    # parameter list.
    while IFS= read -r -d '' eparm; do
        execarg+=( "$eparm" )
    done < <(cat /proc/$PPID/cmdline)
    i=0
    ${LOG} "List parameters"
    while ((i < ${#execarg[@]})) ; do
       ${LOG} "$i: ${execarg[$i]}"
       ((i++))
    done
    if [[ ${execarg[0]} == "pppd" ]] ; then
      execarg[0]=/usr/sbin/pppd
    fi

    # Break any recursion loop.
    if [[ -f ${CHAT_WRAPPER_RECURSION} ]] ; then
       ${LOG}  "Failure: modem is still unresponsive after reset"
       ${LOG}  "Failure: Verify that modem and SIM are in place"
       rm -f ${CHAT_WRAPPER_RECURSION}
       exit 1
    fi
    touch ${CHAT_WRAPPER_RECURSION}
    ${LOG} "Bad TTY, possibly due to modem in bad state/no SIM detected"
    ${LOG} "Reset modem, and we relaunch pppd"
    # Our terminal is the modem.  When we reset the modem,
    # we will be sent a SIGHUP.  Ignore it (:).
    trap : SIGHUP
    /usr/sbin/mts-io-sysfs store radio-reset 0
    sleep 5
    count=0
    while ((count < 60)) ; do
      # Wait for radio-reset to get the modem responding
      if [[ $(radio-cmd -t10000 'AT') =~ ^OK ]]; then
        # parent is dying, so remove the pppd locks for the new pppd.
        for f in /run/lock/LCK..modem_at0 /run/lock/LCK..modem_at1 ; do
          if [[ -f $f ]] ; then
            mypid=$(cat $f)
            ${LOG} "PPID is $PPID, pid is $mypid"
            # Remove the lock, if it belongs to our parent, pppd
            if [ $mypid = $PPID ] ; then
              ${LOG} "match $mypid $PPID"
              sleep 60
              rm -f $f
            else
              ${LOG} "mismatch |$mypid| |$PPID|"
            fi
          fi
        done
        # Locks gone, so start new pppd
        nohup "${execarg[@]}" >/dev/null 2>&1 &
        # Tell our parent we failed, which causes our pppd to terminate.
        exit 1
      else
        sleep 5
      fi
    done
    ${LOG} "ERROR: After five minutes the modem is still not ready"
    ${LOG} "ERROR: Verify that SIM is in place"
    exit 1
  fi
  return 0
} # End of sanity function

# If > 0, need to wait because we were not registered.
WAITREG=0

[[ -f $CONFIG ]] || exit 1

. ${CONFIG} 

: ${REGWAITTIME:=300}
: ${FINALWAIT:=5}
: ${COPSWAIT:=10}
: ${CFUNWAIT:=10}

: ${LOG:="/usr/bin/logger -t ${NAME} -p daemon.notice"}

${LOG} Timeout is $REGWAITTIME, execute "$@" 
((i=$#))
chatscript="${!i}"

${LOG} Parsing chat script "$chatscript"
# CONTEXT is last context string in chat script
CONTEXT=$(egrep "^#MT[[:space:]]+(AT\+CGDCONT=.*)" ${chatscript} | tail -1)
if ((${#CONTEXT} == 0)) ; then
    CONTEXT=$(egrep "^[^#]+AT\+CGDCONT=" ${chatscript} | tail -1)
    [[ $CONTEXT =~ \'(AT\+CGDCONT=([0-9]+)[^$\']+) ]]
else
    [[ $CONTEXT =~ (AT\+CGDCONT=([0-9]+).*)$ ]]
fi

# CONTEXTNUM is the context number that is configured in the dialer.
CONTEXT="${BASH_REMATCH[1]}"
if ((${#CONTEXT} == 0)) ; then
	${LOG} No context specifiction in the chat script
        finish "$@"
	# NOTREACHED
fi
((CONTEXTNUM=${BASH_REMATCH[2]}))

# Make sure CFUN=1, in case the last pppd was aborted with it set to 0.
${LOG} "Verify CFUN=1"
cfun=$(/usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+CFUN?')
result1=$?
if ((result1 != 0)) || ((${#cfun} == 0)) ; then
   ${LOG} "Is modem in bad state -- \"CFUN?\" is broken?"
   sanity
   ((WAITREG++))
fi
if ! [[ $cfun =~ ^\+CFUN:\ 1[,[:space:]] ]] ; then
    /usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+CFUN=1'
    ${LOG} "Just set CFUN=1 so wait ${CFUNWAIT} seconds"
    sleep ${CFUNWAIT}
    ((WAITREG++))
fi

${LOG} "Using Context ${CONTEXTNUM} based on chat script: ${CONTEXT}"


# At this point if there is no context number, we can skip everything else.

# Get Modem's context settings
MCONTEXT=$(/usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+CGDCONT?' 2>&1 | tr -d '\r')
if [[ $MCONTEXT =~ ^[Ee][Rr][Rr][Oo][Rr] ]] ; then
    RADIOOPTION="${RADIOOPTION2}"
    sleep 1
    MCONTEXT=$(/usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+CGDCONT?' 2>&1 | tr -d '\r')
    CRESULT=$?
fi
	
if ! [[ $MCONTEXT =~ \+CGDCONT:[[:space:]]+${CONTEXTNUM},\"([^\"]*)\",\"([^\"]*)\",\"([^\"]*)\",([0-9]+),([0-9]+)([^$'\n']*) ]] ; then
    logger -s -p daemon.error "No valid context in modem.  Is it ready?"
    echo "$MCONTEXT" | logger -s -p daemon.error
    echo "Result is $CRESULT" | logger -s -p daemon.error 
    if [[ $MCONTEXT =~ ^[Ee][Rr][Rr][Oo][Rr] ]] ; then
        logger -s -p daemon.error "Context query response error.  Diagnose ..."
        sanity
    fi
fi

MPDP="${BASH_REMATCH[1]}"
MAPN="${BASH_REMATCH[2]}"
MADDR="${BASH_REMATCH[3]}"
MDCOMP="${BASH_REMATCH[4]}"
MHCOMP="${BASH_REMATCH[5]}"
MFULLBOAT="${BASH_REMATCH[6]}"

[[ $CONTEXT =~ AT\+CGDCONT=${CONTEXTNUM},\"([^\"]*)\",\"([^\"]*)\"(,\"([^\"]*)\"(,([0-9]+)(,([0-9]+)(,[^\']*))*)*)* ]]
PDP="${BASH_REMATCH[1]}"
APN="${BASH_REMATCH[2]}"
ADDR="${BASH_REMATCH[4]}"  # Optional
DCOMP="${BASH_REMATCH[6]}"  # Optional
HCOMP="${BASH_REMATCH[8]}"  # Optional
FULLBOAT="${BASH_REMATCH[9]}"  # Optional

# On some modems there are more parameters than others.
if [[ $MFULLBOAT != $FULLBOAT ]] ; then
	${LOG} "Only the first five context parameters are considered.  The rest will be ignored."
	${LOG} "modem: \"$MFULLBOAT\""
	${LOG} "chat script: \"$FULLBOAT\""
fi

if ((${#DCOMP} == 0)) ; then
	((DCOMP=0))  # Default
fi
if ((${#HCOMP} == 0)) ; then
	((HCOMP=0))  # Default
fi

# For Quectel, address 0 is expressed as "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0"
Q0ADDR="0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0"
ADDRMATCH=1
if [[ $MADDR != $ADDR ]] ; then
    ADDRMATCH=0
    if [[ $MADDR = $Q0ADDR ]] ; then
         if  [[ -z $ADDR ]] || [[ $ADDR = 0 ]] ; then
             ADDRMATCH=1
         fi
    fi
fi	

# Only update context on a mismatch between chat and modem.
if [[ $MPDP != $PDP ]] || [[ $MAPN != $APN ]] || \
	(( $ADDRMATCH == 0 )) || ((MDCOMP != DCOMP)) || \
	((MHCOMP != HCOMP)) ; then
   ${LOG} "Modem context $MPDP,$MAPN,$MADDR,$MDCOMP,$MHCOMP does not match chat script"
   ${LOG} "Chat script context $PDP,$APN,$ADDR,$DCOMP,$HCOMP does not match the modem"
   if [[ $MPDP != $PDP ]] ; then
	${LOG} "PDP mismatch"
   fi
   if [[ $MAPN != $APN ]] ; then
	${LOG} "APN mismatch"
   fi
   if [[ $MADDR != $ADDR ]] ; then
	${LOG} "ADDR mismatch"
        ${LOG} "Modem Address $MADDR"
        ${LOG} "Chat Address $ADDR"
   fi
   if [[ $MDCOMP != $DCOMP ]] ; then
	${LOG} "DCOMP mismatch"
   fi
   if [[ $MHCOMP != $HCOMP ]] ; then
	${LOG} "HCOMP mismatch"
   fi
   if [[ $MFULLBOAT != $FULLBOAT ]] ; then
	${LOG} "Final parameter mismatches ignored"
	${LOG} "Parameter 6 and up on the modem:"
	${LOG} "\"${MFULLBOAT}\""
	${LOG} "Parameter 6 and up on the chat script:"
	${LOG} "\"${FULLBOAT}\""
   fi
   ${LOG} "$MCONTEXT"
   ${LOG} "Dropping registration with carrier to set context"
   # Need to deregister
   ((WAITREG++))
   /usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+COPS=2'

   count=10
   while ((count > 0)) && ! [[ $($RQCMD --netreg) =~ ^NOT\ REGISTERED$ ]] ; do
      sleep 2
      ((count--))  
   done
   
   # H5 radios do not like addresses that are empty with ""
   if ((${#ADDR} == 0)) ; then
     CMDSTR="AT+CGDCONT=${CONTEXTNUM},\"${PDP}\",\"${APN}\",,$DCOMP,${HCOMP}${FULLBOAT}"
   else
     CMDSTR="AT+CGDCONT=${CONTEXTNUM},\"${PDP}\",\"${APN}\",\"${ADDR}\",$DCOMP,${HCOMP}${FULLBOAT}"
   fi
   ${LOG} "Issued command /usr/bin/radio-cmd ${RADIOOPTION} -t10000 ..."
   ${LOG} "... ${CMDSTR}"

   # If we fail to set the APN, sleep and try it again for up to 10 seconds.
   result=1
   count=10
   while ((result != 0)) && ((count > 0)) ; do 
     ((count--)) || true
     LOGMSG=$(/usr/bin/radio-cmd ${RADIOOPTION} -t10000 "${CMDSTR}" 2>&1)
     result=$?
     ${LOG} "Setting context: Result ${result}, Got response ${LOGMSG}"
     if [[ $LOGMSG =~ ERROR ]] ; then
	result=1
     fi
     sleep 1
   done

   # re-enable the modem to defaults.
   /usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+COPS=0'

   # Some older modems will not re-register after the COPS
   # command if you do not reset them using CFUN.
   /usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+CFUN=0'
   ${LOG} "Set COPS=0, CFUN=1, so wait ${CFUNWAIT} seconds"
   sleep ${CFUNWAIT}
   /usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+CFUN=1'

   sleep ${CFUNWAIT}

   # Abort PPP if the Context is not correct.  We don't want
   # to cause the carrier to disable the account by dialing
   # out with a bad APN.
   if ((result != 0)) ; then
	${LOG} "AT+CGDCONT failed, aborting"
	exit $result
   fi
   sleep 1
   ${LOG} "New context is set.  Wait up to $REGWAITTIME seconds to register"
else
    ${LOG} "Context $CONTEXTNUM matches  verify COPS, then wait for registration."
    #  Check and set COPS and CFUN to be sure we were not interrupted at some point
    # in the past.
    cops=$(/usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+COPS?')
    result0=$?

    if ((result0 != 0)) || ! [[ $cops =~ ^\+COPS:\ 0, ]] ; then
        /usr/bin/radio-cmd ${RADIOOPTION} -t10000 'AT+COPS=0'
        ((WAITREG++))
        ${LOG} "Just set COPS=0 so wait ${COPSWAIT} seconds"
        sleep ${COPSWAIT}
    fi

fi
# Wait for registration
uptime=$(cat /proc/uptime)
[[ $uptime =~ ^([^\.]*) ]]
t0=${BASH_REMATCH[1]}
while ! [[ $($RQCMD --netreg) =~ ^(REGISTERED|ROAMING)$ ]] ; do
    sleep 5
    ((WAITREG++))
    uptime=$(cat /proc/uptime)
    [[ $uptime =~ ^([^\.]*) ]]
    t1=${BASH_REMATCH[1]}
    if ((t1-t0 > REGWAITTIME)) ; then
        ${LOG} "$((t1-t0)) seconds has expired without registration"
        sanity
    fi	
done
uptime=$(cat /proc/uptime)
[[ $uptime =~ ^([^\.]*) ]]
t1=${BASH_REMATCH[1]}
${LOG} "Re-registered in $((t1-t0)) seconds"
if ((WAITREG > 0)) ; then
  ${LOG} "Wait ${FINALWAIT} more seconds"
  sleep $FINALWAIT
fi
sanity

rm -f ${CHAT_WRAPPER_RECURSION}
finish "$@"

# NOTREACHED