include/ssh: Import ssh module from toolbox

This commit imports the ssh module that has previously been removed
from the toolbox core package.

diff --git a/include/ssh.sh b/include/ssh.sh
new file mode 100755 (executable)
index 0000000..39e5ba2
--- /dev/null
+++ b/include/ssh.sh
@@ -0,0 +1,204 @@
+#!/bin/bash
+
+# ssh.sh - Toolbox module for SSH tunnels and dynamic proxies
+# Copyright (C) 2021 Matthias Kruk
+#
+# 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 3 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, see <https://www.gnu.org/licenses/>.
+
+__init() {
+       if ! include "log"; then
+               return 1
+       fi
+
+       declare -xgr __ssh_socket_dir="$TOOLBOX_HOME/ssh"
+
+       return 0
+}
+
+_ssh_get_socket_dir() {
+       if ! mkdir -p "$__ssh_socket_dir" &> /dev/null; then
+               error "Could not create $__ssh_socket_dir"
+               return 1
+       fi
+
+       echo "$__ssh_socket_dir"
+       return 0
+}
+
+_ssh_tunnel_ctrl_socket_name() {
+       local host
+       local port
+       local lport
+
+       local sockdir
+
+       host="$1"
+       port="$2"
+       lport="$3"
+
+       if ! sockdir=$(_ssh_get_socket_dir); then
+               return 1
+       fi
+
+       echo "$sockdir/tunnel-$lport-$host-$port.sock"
+       return 0
+}
+
+_ssh_proxy_ctrl_socket_name() {
+       local host
+       local port
+
+       local sockdir
+
+       host="$1"
+       port="$2"
+
+       if ! sockdir=$(_ssh_get_socket_dir); then
+               return 1
+       fi
+
+       echo "$sockdir/proxy-$host-$port.sock"
+       return 0
+}
+
+_ssh_make_handle() {
+       local ctrlsock="$1"
+       local hostspec="$2"
+
+       local handle
+
+       if ! handle=$(base64 <<< "$ctrlsock" 2>/dev/null); then
+               return 1
+       fi
+
+       handle+=":"
+
+       if ! handle+=$(base64 <<< "$hostspec" 2>/dev/null); then
+               return 1
+       fi
+
+       echo "$handle"
+       return 0
+}
+
+_ssh_handle_get_ctrlsock() {
+       local handle="$1"
+
+       local ctrlsock
+
+       if ! ctrlsock=$(base64 -d <<< "${handle%%:*}" 2>/dev/null); then
+               return 1
+       fi
+
+       echo "$ctrlsock"
+       return 0
+}
+
+_ssh_handle_get_hostspec() {
+       local handle="$1"
+
+       local hostspec
+
+       if ! hostspec=$(base64 -d <<< "${handle##*:}" 2>/dev/null); then
+               return 1
+       fi
+
+       echo "$hostspec"
+       return 0
+}
+
+ssh_tunnel_open() {
+       local tunnel_host="$1"
+       local tunnel_user="$2"
+       local remote_addr="$3"
+       local remote_port="$4"
+       local local_addr="$5"
+       local local_port="$6"
+
+       local ctrl_sock
+       local addrspec
+       local sshtarget
+       local handle
+
+       addrspec="$local_addr:$local_port:$remote_addr:$remote_port"
+       sshtarget="$tunnel_user@$tunnel_host"
+
+       if ! ctrl_sock=$(_ssh_tunnel_ctrl_socket_name "$remote_addr" \
+                                                     "$remote_port" \
+                                                     "$local_port"); then
+               return 1
+       fi
+
+       if ! handle=$(_ssh_make_handle "$ctrl_sock" "$sshtarget"); then
+               return 1
+       fi
+
+       if ! ssh -M -S "$ctrl_sock" -fnNT -o "ExitOnForwardFailure=yes" \
+            -L "$addrspec" "$sshtarget" > /dev/null; then
+               return 1
+       fi
+
+       echo "$handle"
+       return 0
+}
+
+ssh_proxy_open() {
+       local proxy_host="$1"
+       local proxy_user="$2"
+       local local_addr="$3"
+       local local_port="$4"
+
+       local ctrl_sock
+       local addrspec
+       local sshtarget
+       local handle
+
+       addrspec="$local_addr:$local_port"
+       sshtarget="$proxy_user@$proxy_host"
+
+       if ! ctrl_sock=$(_ssh_proxy_ctrl_socket_name "$local_addr" "$local_port"); then
+               return 1
+       fi
+
+       if ! handle=$(_ssh_make_handle "$ctrl_sock" "$sshtarget"); then
+               return 1
+       fi
+
+       if ! ssh -M -S "$ctrl_sock" -fnNT -o "ExitOnForwardFailure=yes" \
+            -D "$addrspec" "$sshtarget" > /dev/null; then
+               return 1
+       fi
+
+       echo "$handle"
+       return 0
+}
+
+ssh_close() {
+       local handle="$1"
+
+       local ctrlsock
+       local hostspec
+
+       if ! ctrlsock=$(_ssh_handle_get_ctrlsock "$handle") ||
+          ! hostspec=$(_ssh_handle_get_hostspec "$handle"); then
+               log_error "Invalid handle"
+               return 1
+       fi
+
+       if ! ssh -S "$ctrlsock" -O exit "$hostspec" &> /dev/null; then
+               return 1
+       fi
+
+       return 0
+}