Make Cmder work with ssh-agent

agent.cmd

@ECHO OFF
SETLOCAL
GOTO:MAIN

REM
REM Info functions start
REM

REM Display version and copyright information
:VERSION
ECHO,Agent 1.0.0.0 (ssh-agent script for MSYS2)
ECHO,
ECHO,Copyright (C^) 2014-2021 Gregor A. Cieslak.
ECHO,
ECHO,License GPLv3+: GNU GPL version 3 or later ^<https://gnu.org/licenses/gpl.html^>.
ECHO,This is free software: you are free to change and redistribute it.
ECHO,There is NO WARRANTY, to the extent permitted by law.
GOTO:EOF


REM Display usage information
:USAGE
ECHO,Adds missing ssh-keys to an instance of ssh-agent.
ECHO,Starts a new instance if ssh-agent is not running or sock file is invalid.
ECHO,Use with MSYS2 command line tools (https://www.msys2.org/^).
ECHO,
ECHO,Requirements:
ECHO,  %%HOME%%\.ssh folder with ssh keys in any of the following formats:
ECHO,    rsa, dsa, ecdsa, ecdsa_sk, ed25519, ed25519_sk
ECHO,  MSYS2 installation with following command line tools:
ECHO,    cygpath, rm, sed, awk, grep, ps, ssh-add, ssh-keygen, ssh-agent
ECHO,
ECHO,Usage: agent [OPTION]
ECHO,
ECHO,OPTION:
ECHO,  -c, --check    check requirements
ECHO,  -h, --help     display this help text
ECHO,  -k, --kill     kill all ssh-agent processes
ECHO,  -v, --verbose  verbose mode
ECHO,  -V  --version  display version
GOTO:EOF

REM
REM Info functions end
REM


REM
REM Entry point start
REM

:MAIN
REM Parse command line arguments
IF NOT "%~2" == ""      GOTO:USAGE
IF "%~1" == "-h"        GOTO:USAGE
IF "%~1" == "--help"    GOTO:USAGE

IF "%~1" == "-k"        GOTO:KILLSSHAGENT
IF "%~1" == "--kill"    GOTO:KILLSSHAGENT

IF "%~1" == "-c"        GOTO:CHECKREQUIREMENTS
IF "%~1" == "--check"   GOTO:CHECKREQUIREMENTS

IF "%~1" == "-V"        GOTO:VERSION
IF "%~1" == "--version" GOTO:VERSION

REM Check for verbose output
SET "VERBOSE="
IF "%~1" == "-v" (
  SET "VERBOSE=true"
) ELSE IF "%~1" == "--verbose" (
  SET "VERBOSE=true"
) ELSE IF NOT "%~1" == "" GOTO:USAGE

CALL:LOG "[INFO] Adding missing ssh keys:"
CALL:LOG "-------------------------------------------"

REM Set default sock file if missing
SET "DEFAULT_AUTH_SOCK=/tmp/ssh-agent.sock"
IF "%SSH_AUTH_SOCK%" == ""                    GOTO:SETDEFAULTSOCK
IF "%SSH_AUTH_SOCK%" == "%DEFAULT_AUTH_SOCK%" GOTO:SETDEFAULTSOCK

CALL:LOG "[INFO] Checking preexisting ssh-agent sock file"
GOTO:CHECKSOCKFILE


:SETDEFAULTSOCK
SET "SSH_AUTH_SOCK=%DEFAULT_AUTH_SOCK%"
CALL:LOG "[INFO] Checking default ssh-agent sock file"


:CHECKSOCKFILE
REM Check if path to socket file is available
FOR /f "tokens=*" %%I IN ('cygpath -w "%SSH_AUTH_SOCK%"') DO SET "VAR=%%I"
IF "%SSH_AUTH_SOCK%" == "%DEFAULT_AUTH_SOCK%" (
  IF NOT EXIST "%VAR%" GOTO:RUNAGENT
) ELSE (
  IF NOT EXIST "%VAR%" GOTO:SETDEFAULTSOCK
)
CALL:LOG "[INFO] Found ssh-agent sock file"

REM Check if an ssh-agent is running
FOR /f "tokens=*" %%I IN ('ps ^| grep ssh-agent ^| sed "s/^ *\([0-9]\+\) .*/\1/"') DO SET "VAR=%%I"
IF "%SSH_AUTH_SOCK%" == "%DEFAULT_AUTH_SOCK%" (
  IF "%VAR%" == "" GOTO:RUNAGENT
) ELSE (
  IF "%VAR%" == "" GOTO:CHECKDEFAULTSOCK
)
CALL:LOG "[INFO] Found ssh-agent process"

REM Check if socket file is valid
ssh-add -l 1> NUL 2>&1
IF ERRORLEVEL 1 (
  CALL:LOG "[INFO] Failed to validate sock file"
  IF "%SSH_AUTH_SOCK%" == "%DEFAULT_AUTH_SOCK%" (
    GOTO:RUNAGENT
  ) ELSE (
    GOTO:SETDEFAULTSOCK
  )
)
CALL:LOG "[INFO] Found valid sock file"
GOTO:ADDKEYS


:RUNAGENT
CALL:LOG "[INFO] Starting new ssh-agent"
REM Don't delete %%SSH_AUTH_SOCK%% - could be set to a dangerous path
IF NOT "%SSH_AUTH_SOCK%" == "%DEFAULT_AUTH_SOCK%" GOTO:SKIPDELETESOCK

REM Remove old default socket file if available
FOR /f "tokens=*" %%I IN ('cygpath -w "%DEFAULT_AUTH_SOCK%"') DO SET "VAR=%%I"
IF EXIST "%VAR%" rm -f -- "%DEFAULT_AUTH_SOCK%"
SET "SSH_AUTH_SOCK=%DEFAULT_AUTH_SOCK%"
:SKIPDELETESOCK

REM Run ssh-agent and save (last) PID in VAR
SET "VAR="
FOR /f "tokens=*" %%J IN ('ssh-agent -a "%SSH_AUTH_SOCK%"') DO FOR /f "tokens=*" %%K IN ('ECHO,%%J ^| grep "SSH_AGENT_PID" ^| sed "s/^SSH_AGENT_PID=\([0-9]\+\); .*/\1/"') DO SET "VAR=%%K"


:ADDKEYS
SET "SSH_AGENT_PID=%VAR%"

REM Check if ssh keys are known
SET "KEYS="
SET /A "KEYCOUNT=0"
FOR /f "tokens=*" %%I IN ('DIR /B "%HOME%\.ssh\*_rsa" "%HOME%\.ssh\*_dsa" "%HOME%\.ssh\*_ecdsa" "%HOME%\.ssh\*_ecdsa_sk" "%HOME%\.ssh\*_ed25519" "%HOME%\.ssh\*_ed25519_sk" 2^> NUL') DO CALL:CHECKKEY %%I

REM Print ssh key count
IF %KEYCOUNT% == 1 (
  CALL:LOG "[INFO] Found %KEYCOUNT% ssh key"
) ELSE (
  CALL:LOG "[INFO] Found %KEYCOUNT% ssh keys"
)

REM Add all missing ssh keys
IF NOT "%KEYS%" == "" (
  CALL:LOG "[INFO] Adding ssh keys"
  ssh-add %KEYS%
) ELSE (
  CALL:LOG "[INFO] All ssh keys already added"
)

CALL:LOG "==========================================="
CALL:LOG "[INFO] Done"

ENDLOCAL & SET "SSH_AGENT_PID=%SSH_AGENT_PID%" & SET "SSH_AUTH_SOCK=%SSH_AUTH_SOCK%"
GOTO:EOF

REM
REM Entry point end
REM


REM
REM Functions start
REM

REM Check if ssh key has to be added
:CHECKKEY
SET /A "KEYCOUNT=KEYCOUNT+1"
SET "FINGERPRINT="
FOR /f "tokens=*" %%J IN ('ssh-keygen -lf "%HOME%\.ssh\%1" 2^>nul ^| awk "{print $2}"') DO SET "FINGERPRINT=%%J"
IF "%FINGERPRINT%" == "" GOTO:EOF

SET "VAR="
FOR /f "tokens=*" %%J IN ('ssh-add -l 2^>nul ^| awk "{print $2}" ^| grep "%FINGERPRINT%"') DO SET "VAR=%%J"
IF "%VAR%" == "" SET "KEYS='%HOME%\.ssh\%1' %KEYS%"
GOTO:EOF


REM Output text in verbose mode
:LOG
IF "%VERBOSE%" == "" GOTO:EOF
ECHO,%~1
GOTO:EOF


REM Check if required command line tools, folders and ssh keys are available
:CHECKREQUIREMENTS
SET "FAILED="
ECHO,[INFO] Checking requirements...
ECHO,-------------------------------------------

CALL:CHECKPROGEXISTS cygpath
IF NOT "%FAILED%"=="" GOTO:SKIPTMPPATHCHECK

FOR /f "tokens=*" %%I IN ('cygpath -w /tmp') DO SET "TMPPATH=%%I"
IF EXIST "%TMPPATH%" (
  ECHO,[OK]   found /tmp folder
) ELSE (
  ECHO,[FAIL] missing /tmp folder
  SET "FAILED=true"
)

:SKIPTMPPATHCHECK
IF EXIST "%HOME%\.ssh\" (
  ECHO,[OK]   found %%HOME%%\.ssh folder
) ELSE (
  ECHO,[FAIL] missing %%HOME%%\.ssh folder
  SET "FAILED=true"
)

CALL:CHECKPROGEXISTS rm
CALL:CHECKPROGEXISTS sed
CALL:CHECKPROGEXISTS awk
CALL:CHECKPROGEXISTS grep
CALL:CHECKPROGEXISTS ps
CALL:CHECKPROGEXISTS ssh-add
CALL:CHECKPROGEXISTS ssh-keygen
CALL:CHECKPROGEXISTS ssh-agent

SET "KEYS="
SET /A "KEYCOUNT=0"
FOR /f "tokens=*" %%I IN ('DIR /B "%HOME%\.ssh\*_rsa" "%HOME%\.ssh\*_dsa" "%HOME%\.ssh\*_ecdsa" "%HOME%\.ssh\*_ecdsa_sk" "%HOME%\.ssh\*_ed25519" "%HOME%\.ssh\*_ed25519_sk" 2^> NUL') DO CALL:CHECKKEY %%I
IF NOT %KEYCOUNT% == 0 (
  IF %KEYCOUNT% == 1 (
    ECHO,[OK]   found %KEYCOUNT% ssh key
  ) ELSE (
    ECHO,[OK]   found %KEYCOUNT% ssh keys
  )
) ELSE (
  ECHO,[FAIL] missing ssh keys
  SET "FAILED=true"
)

ECHO,===========================================
IF "%FAILED%"=="" (
  ECHO,[OK]   Success! All requirements are met
) ELSE (
  ECHO,[FAIL] Failure! Some requirements are not met!
)
GOTO:EOF


REM Check if programm is in path
:CHECKPROGEXISTS
WHERE /q %1
IF ERRORLEVEL 1 (
  ECHO,[FAIL] missing %1 in PATH
  SET "FAILED=true"
) ELSE (
  ECHO,[OK]   found %1
)
GOTO:EOF


REM Kills all ssh-agent processes
:KILLSSHAGENT
SET /A "KILLCOUNT=0"
FOR /f "tokens=*" %%I IN ('ps ^| grep ssh-agent ^| awk "{print $1}"') DO (
  IF NOT "%%I" == "" (
    KILL %%I
    SET /A "KILLCOUNT=KILLCOUNT+1"
  )
)

ECHO,[INFO] killed %KILLCOUNT% ssh-agent processes
GOTO:EOF

REM
REM Functions end
REM

Hey everyone since this script is not really necessary for cmder,
I decided to fix and update this script to work with MSYS2 (and possibly cygwin).
Cmder provides a start-ssh-agent script from git-for-windows by default.

Updated and extended the script:
Add license
Add kill command
Add verbose output
Add help/usage info
Add version/license info
Add dependency check support
Add support for adding all kinds of ssh keys
Add comments
Add support for checking already set SSH_AUTH_SOCK before using DEFAULT_AUTH_SOCK
Modify use ECHO, for faster output
Fix don't leak/overwrite environment variables except SSH_AUTH_SOCK and SSH_AGENT_PID if successfull
Fix check for the sock file in the correct folder (/tmp != %TEMP%)
Fix valid sock file check needs to check with fingerprint instead of non working path

Have fun ;)