(Tcl) Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time.

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load ./chilkat.dll

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# First, let's get the current date/time from time-c.nist.gov
set socket [new_CkSocket]

# Connect to an NIST time server and read the current date/time
set maxWaitMs 8000
set useTls 0
set success [CkSocket_Connect $socket "time-c.nist.gov" 37 $useTls $maxWaitMs]
if {$success != 1} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSocket $socket
    exit
}

# The time server will send a big-endian 32-bit integer representing
# the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
# The ReceiveInt32 method will receive a 4-byte integer, but returns
# 1 or 0 to indicate success.  If successful, the integer
# is obtained via the ReceivedInt property.
set bigEndian 1
set success [CkSocket_ReceiveInt32 $socket $bigEndian]
if {$success != 1} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSocket $socket
    exit
}

set dt [new_CkDateTime]

CkDateTime_SetFromNtpTime $dt [CkSocket_get_ReceivedInt $socket]

# Show the current local date/time
set bLocalTime 1
puts "Current local date/time: [CkDateTime_getAsRfc822 $dt $bLocalTime]"

set maxWaitMs 10
CkSocket_Close $socket $maxWaitMs

# ------------------------------------------------------------------------
# OK, we have the current date/time.  We'll use it to set the IAT property
# in the code below.

# First load the JSON key into a string.
set fac [new_CkFileAccess]

set jsonKey [CkFileAccess_readEntireTextFile $fac "qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json" "utf-8"]
if {[CkFileAccess_get_LastMethodSuccess $fac] != 1} then {
    puts [CkFileAccess_lastErrorText $fac]
    delete_CkSocket $socket
    delete_CkDateTime $dt
    delete_CkFileAccess $fac
    exit
}

# A JSON private key should look like this:

# 	{
# 	  "type": "service_account",
# 	  "project_id": "chilkattest-1350",
# 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
# 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
# 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
# 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
# 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
# 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
# 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
# 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
# 	}

set gAuth [new_CkAuthGoogle]

CkAuthGoogle_put_JsonKey $gAuth $jsonKey

# Choose a scope.
CkAuthGoogle_put_Scope $gAuth "https://www.googleapis.com/auth/cloud-platform"

# Request an access token that is valid for this many seconds.
CkAuthGoogle_put_ExpireNumSeconds $gAuth 3600

# If the application is requesting delegated access:
# The email address of the user for which the application is requesting delegated access,
# then set the email address here. (Otherwise leave it empty.)
CkAuthGoogle_put_SubEmailAddress $gAuth ""

# ------------------------------------------------------------------------
# Set the IAT using the date/time from the NIST time server.
set unixTime [CkDateTime_GetAsUnixTime $dt 0]
puts "unixTime = $unixTime"
CkAuthGoogle_put_Iat $gAuth $unixTime

# Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
# The Chilkat socket object is used so that the connection can be established
# through proxies or an SSH tunnel if desired.
set tlsSock [new_CkSocket]

set success [CkSocket_Connect $tlsSock "www.googleapis.com" 443 1 5000]
if {$success != 1} then {
    puts [CkSocket_lastErrorText $tlsSock]
    delete_CkSocket $socket
    delete_CkDateTime $dt
    delete_CkFileAccess $fac
    delete_CkAuthGoogle $gAuth
    delete_CkSocket $tlsSock
    exit
}

# Send the request to obtain the access token.
set success [CkAuthGoogle_ObtainAccessToken $gAuth $tlsSock]
if {$success != 1} then {
    puts [CkAuthGoogle_lastErrorText $gAuth]
    delete_CkSocket $socket
    delete_CkDateTime $dt
    delete_CkFileAccess $fac
    delete_CkAuthGoogle $gAuth
    delete_CkSocket $tlsSock
    exit
}

# Examine the access token:
puts "Access Token: [CkAuthGoogle_accessToken $gAuth]"

delete_CkSocket $socket
delete_CkDateTime $dt
delete_CkFileAccess $fac
delete_CkAuthGoogle $gAuth
delete_CkSocket $tlsSock