#!/bin/sh
# This file is part of Epoptes, https://epoptes.org
# Copyright 2017-2018 the Epoptes team, see AUTHORS.
# SPDX-License-Identifier: GPL-3.0-or-later

usage() {
    printf "Usage: $0\n%s" \
'
Receive remote shells over secure connections.
The clients are supposed to use `share-terminal`.
'
}

die() {
    printf "%s\n" "$@" >&2
    exit 1
}

# "phase2" is passed when socat receives a connection
if [ "$1" = "phase2" ]; then
    # Run this command on the client, and parse its output
    printf '%s\n' ' printf "\n%s\n" "suggested-xterm-parameters $(hostname) $(stty size) "; clear' &
    while read -r guard hostname lines columns junk; do
        test "$guard" = "suggested-xterm-parameters" && break
    done
    # Allow the user to define custom XTERM_PARAMS in the environment
    exec xterm $XTERM_PARAMS -T "Shared@${hostname}" -geometry "${columns}x${lines}" -e "socat fd:9 stdio,raw,echo=0" 9>&0
elif [ "$#" -gt 0 ]; then
    die "$(usage)"
fi

test -n "$DISPLAY" || die "Please run $0 from within Xorg."
command -v socat >/dev/null 2>&1 || die "Please install socat."
command -v xterm >/dev/null 2>&1  || die "Please install xterm."

printf "Generating an openssl certificate to secure connections..."

# Save some time by doing openssl and wget in parallel
PEM=$(mktemp -t receive-terminals-XXXXX.pem)
trap "rm -f $PEM" INT QUIT
openssl req -batch -x509 -days 365 -nodes -newkey rsa:4096 -out "$PEM" -keyout "$PEM" 2>/dev/null &

# Set your external IP in the environment if you don't want it auto-detected
test -n "$IP" || IP=$(wget -T 5 -q http://alkisg.mysch.gr/ip/ -O - | sed -n "s/^IP='\(.*\)'/\\1/p")
# Falling back to the internal IP
test -n "$IP" || IP=$(ip route get 8.8.8.8 | sed -n 's/.*dev *\([^ ]*\).*src *\([^ ]*\).*/\2/p')
test -n "$IP" || IP="your-ip"

# Wait for openssl to finish
wait

printf "%s" \
" [OK]

Accepting remote shell secure connections. Clients can connect by running:
  /usr/share/epoptes-client/share-terminal $IP
If they don't have epoptes-client installed, they can run this instead:
  TERM=xterm COLUMNS=\$COLUMNS LINES=\$LINES socat SYSTEM:\"sleep 1; exec screen -xRR ra\",pty,stderr openssl-connect:$IP:5499,verify=0 & screen -l -S ra
Press Ctrl+C to end.
"

# We don't want `exec socat` because we have a trap that removes the PEM
socat openssl-listen:5499,cert="$PEM",reuseaddr,keepalive=1,fork,verify=0 EXEC:"$0 phase2"