#!/bin/bash
set -e
function help
{
    PROGNAME=${0##*/}
    cat <<EOF
$PROGNAME: Save TunTox numbers in OpenSSH contact list.

Usage: $PROGNAME  add       <name>  <TunTox Number>
Usage: $PROGNAME  connect   <name>  <TunTox Number>


For example, first do this:

       $PROGNAME  add       billy   4BC18209278C9B2AA1BF9B9B27E671FC47D3DE3B15D175A63CC2C6E01B532A4CAE3D4BE083C8

Then you can connect to billy's SSH server through Tox with this command:

       ssh billy



It will use Tox for connectivity but provide all the features of ssh (such as
git, rsync, tunneling with -w, etc).



It is also possible to use this command:

       $PROGNAME  connect   <name>  <TunTox Number>
       $PROGNAME  connect   billy   4BC18209278C9B2AA1BF9B9B27E671FC47D3DE3B15D175A63CC2C6E01B532A4CAE3D4BE083C8

...which will first add the entry, if necessary, and then connect by running the
command 'ssh billy'.


EOF
}

function main
{
    if [ $# = 0 ]
    then
        help
        exit
    fi
    case "$1" in
        add)
            shift
            tokssh_add "$@"
            ;;
        connect)
            shift
            exists_ok
            tokssh_add "$@"
            exec ssh "$name"
            ;;
        *)
            help
            exit 1
            ;;
    esac
    exit
}


function ssh_config_fragment
{
    cat <<EOF
Host $name
# Cryptographic trust comes from Hostname, which is a Tox key hash.
#
# We know we're talking to someone who has this key hash because Tox crypto
# verifies.
#
# Thus we can safely disable StrictHostKeyChecking, and we can use this as a
# secure channel to obtain and save SSH public keys for the remote server.

StrictHostKeyChecking=no
Hostname=$toxid
ProxyCommand=tuntox -C ~/.tuntox/persist -i %h -W localhost:%p
EOF
}

function tokssh_add
{
    if [ $# != 2 ]
    then
        help
        exit 1
    fi
    if [ ${#2} = 76 ]
    then
        name=$1
        toxid=$2
    elif [ ${#1} = 76 ]
    then
        name=$2
        toxid=$1
    else
        echo "$0: Error: Invalid ToxID: $2" >&2
        exit 1
    fi
    mkdir -p ~/.ssh/config.d
    mkdir -p ~/.tuntox/persist
    grep -q '^Include config\.d/\*' ~/.ssh/config || sed -i -e '1i Include config.d/*' ~/.ssh/config
    if grep -q "^Host $name" ~/.ssh/config
    then
        if [ "$exists_ok" ]
        then
            return
        else
            echo "$0: Error: name exists in your .ssh/config.  Refused to edit.  name=$name" >&2
            exit 1
        fi
    fi
    out=~/.ssh/config.d/$name
    if [ -e "$out" ]
    then
        if [ "$exists_ok" ]
        then
            return
        else
            echo "$0: Error: file exists.  Refused to edit.  file=$out" >&2
            exit 1
        fi
    else
        ssh_config_fragment > "$out"
    fi
}

main "$@"