ssh-find-agent.sh

# Copyright (C) 2011 by Wayne Walker <wwalker@solid-constructs.com>
#
# Released under one of the versions of the MIT License.
#
# Copyright (C) 2011 by Wayne Walker <wwalker@solid-constructs.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

_LIVE_AGENT_LIST=""
declare -a _LIVE_AGENT_SOCK_LIST
_LIVE_AGENT_SOCK_LIST=()

_debug_print() {
	if [[ $_DEBUG -gt 0 ]]
	then
		printf "%s\n" $1
	fi
}

find_all_ssh_agent_sockets() {
	_SSH_AGENT_SOCKETS=`find /tmp/ -type s -name agent.\* 2> /dev/null | grep '/tmp/ssh-.*/agent.*'`
	_debug_print "$_SSH_AGENT_SOCKETS"
}

find_all_gpg_agent_sockets() {
	_GPG_AGENT_SOCKETS=`find /tmp/ -type s -name S.gpg-agent.ssh 2> /dev/null | grep '/tmp/gpg-.*/S.gpg-agent.ssh'`
	_debug_print "$_GPG_AGENT_SOCKETS"
}

find_all_gnome_keyring_agent_sockets() {
	_GNOME_KEYRING_AGENT_SOCKETS=`find /tmp/ -type s -name ssh 2> /dev/null | grep '/tmp/keyring-.*/ssh$'`
	_debug_print "$_GNOME_KEYRING_AGENT_SOCKETS"
}

find_all_osx_keychain_agent_sockets() {
	[[ -n "$TMPDIR" ]] || TMPDIR=/tmp
	_OSX_KEYCHAIN_AGENT_SOCKETS=`find $TMPDIR/ -type s -regex '.*/ssh-.*/agent..*$' 2> /dev/null`
	_debug_print "$_OSX_KEYCHAIN_AGENT_SOCKETS"
}

test_agent_socket() {
	local SOCKET=$1
	SSH_AUTH_SOCK=$SOCKET ssh-add -l 2> /dev/null > /dev/null
	result=$?

	_debug_print $result

	if [[ $result -eq 0 ]]
	then
		# contactible and has keys loaded
		_KEY_COUNT=`SSH_AUTH_SOCK=$SOCKET ssh-add -l | wc -l | tr -d ' '`
	fi

	if [[ $result -eq 1 ]]
	then
		# contactible butno keys loaded
		_KEY_COUNT=0
	fi

	if [[ ( ( $result -eq 0 ) || ( $result -eq 1 ) ) ]]
	then
		if [[ -n "$_LIVE_AGENT_LIST" ]]
		then
			_LIVE_AGENT_LIST="${_LIVE_AGENT_LIST} ${SOCKET}:$_KEY_COUNT"
		else
			_LIVE_AGENT_LIST="${SOCKET}:$_KEY_COUNT"
		fi
		return 0
	fi

	return 1
}

find_live_gnome_keyring_agents() {
	for i in $_GNOME_KEYRING_AGENT_SOCKETS
	do
		test_agent_socket $i
	done
}

find_live_osx_keychain_agents() {
	for i in $_OSX_KEYCHAIN_AGENT_SOCKETS
	do
		test_agent_socket $i
	done
}

find_live_gpg_agents() {
	for i in $_GPG_AGENT_SOCKETS
	do
		test_agent_socket $i
	done
}

find_live_ssh_agents() {
	for i in $_SSH_AGENT_SOCKETS
	do
		test_agent_socket $i
	done
}

function fingerprints() {
    local file="$1"
    while read l; do
        [[ -n $l && ${l###} = $l ]] && ssh-keygen -l -f /dev/stdin <<<$l
    done < $file
}

find_all_agent_sockets() {
	_SHOW_IDENTITY=0
	if [ "$1" = "-i" ] ; then
		_SHOW_IDENTITY=1
	fi
	_LIVE_AGENT_LIST=
	find_all_ssh_agent_sockets
	find_all_gpg_agent_sockets
	find_all_gnome_keyring_agent_sockets
	find_all_osx_keychain_agent_sockets
	find_live_ssh_agents
	find_live_gpg_agents
	find_live_gnome_keyring_agents
	find_live_osx_keychain_agents
	_debug_print "$_LIVE_AGENT_LIST"
	_LIVE_AGENT_LIST=$(echo $_LIVE_AGENT_LIST | tr ' ' '\n' | sort -n -t: -k 2 -k 1 | uniq)
	_LIVE_AGENT_SOCK_LIST=()
	_debug_print "SORTED: $_LIVE_AGENT_LIST"
	if [ -e ~/.ssh/authorized_keys ] ; then
  		_FINGERPRINTS=$(fingerprints ~/.ssh/authorized_keys)
	fi
	if [[ $_SHOW_IDENTITY -gt 0 ]]
	then
		i=0
		for a in $_LIVE_AGENT_LIST ; do
			sock=${a/:*/} 
			_LIVE_AGENT_SOCK_LIST[$i]=$sock
      # technically we could have multiple keys forwarded
      # But I haven't seen anyone do it
      akeys=$(SSH_AUTH_SOCK=$sock ssh-add -l)
      key_size=$(echo ${akeys} | awk '{print $1}')
      fingerprint=$(echo ${akeys} | awk '{print $2}')
      remote_name=$(echo ${akeys} | awk '{print $3}')
      if [ -e ~/.ssh/authorized_keys ] ; then
      	authorized_entry=$(fingerprints ~/.ssh/authorized_keys | grep $fingerprint)
      fi
      comment=$(echo ${authorized_entry} | awk '{print $3,$4,$5,$6,$7}')
		  printf "export SSH_AUTH_SOCK=%s \t#%i) \t%s\n" "$sock" $((i+1)) "$comment"
			i=$((i+1))
		done
	else
		printf "%s\n" "$_LIVE_AGENT_LIST" | sed -e 's/ /\n/g' | sort -n -t: -k 2 -k 1
	fi
}

set_ssh_agent_socket() {
	if [ "$1" = "-c" -o "$1" = "--choose" ]
	then
		find_all_agent_sockets -i

		if [ -z "$_LIVE_AGENT_LIST" ] ; then
			echo "No agents found"
			return 1
		fi

		echo -n "Choose (1-${#_LIVE_AGENT_SOCK_LIST[@]})? "
		read choice
		if [ -n "$choice" ]
		then
			n=$((choice-1))
			if [ -z "${_LIVE_AGENT_SOCK_LIST[$n]}" ] ; then
				echo "Invalid choice"
				return 1
			fi
			echo "Setting export SSH_AUTH_SOCK=${_LIVE_AGENT_SOCK_LIST[$n]}"
			export SSH_AUTH_SOCK=${_LIVE_AGENT_SOCK_LIST[$n]}
		fi
	else
		# Choose the first available
		SOCK=$(find_all_agent_sockets|tail -n 1|awk -F: '{print $1}')
		if [ -z "$SOCK" ] ; then
			return 1
		fi
		export SSH_AUTH_SOCK=$SOCK
	fi

	return 0
}

ssh-find-agent() {
	if [ "$1" = "-c" -o "$1" = "--choose" ]
	then
		set_ssh_agent_socket -c
		return $?
	elif [ "$1" = "-a" -o "$1" = "--auto" ]
	then
		set_ssh_agent_socket
		return $?
	else
		find_all_agent_sockets -i
		return 0
	fi
}