Xbase++

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. Xbase++

LOCAL nSuccess
LOCAL oSocket
LOCAL nMaxWaitMs
LOCAL nUseTls
LOCAL nBigEndian
LOCAL oDt
LOCAL nBLocalTime
LOCAL oFac
LOCAL cJsonKey
LOCAL oGAuth
LOCAL nUnixTime
LOCAL oTlsSock

nSuccess := 0

//  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
oSocket := CreateObject("Chilkat.Socket")

//  Connect to an NIST time server and read the current date/time
nMaxWaitMs := 8000
nUseTls := 0
nSuccess := oSocket:Connect("time-c.nist.gov", 37, nUseTls, nMaxWaitMs)
IF (nSuccess != 1)
    ? oSocket:LastErrorText
    oSocket:destroy()
    RETURN
ENDIF

//  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.
nBigEndian := 1
nSuccess := oSocket:ReceiveInt32(nBigEndian)
IF (nSuccess != 1)
    ? oSocket:LastErrorText
    oSocket:destroy()
    RETURN
ENDIF

oDt := CreateObject("Chilkat.CkDateTime")
oDt:SetFromNtpTime(oSocket:ReceivedInt)

//  Show the current local date/time
nBLocalTime := 1
? "Current local date/time: " + oDt:GetAsRfc822(nBLocalTime)

nMaxWaitMs := 10
oSocket:Close(nMaxWaitMs)

//  ------------------------------------------------------------------------
//  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.
oFac := CreateObject("Chilkat.FileAccess")
cJsonKey := oFac:ReadEntireTextFile("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json", "utf-8")
IF (oFac:LastMethodSuccess != 1)
    ? oFac:LastErrorText
    oSocket:destroy()
    oDt:destroy()
    oFac:destroy()
    RETURN
ENDIF

//  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"
//  	}

oGAuth := CreateObject("Chilkat.AuthGoogle")
oGAuth:JsonKey := cJsonKey

//  Choose a scope.
oGAuth:Scope := "https://www.googleapis.com/auth/cloud-platform"

//  Request an access token that is valid for this many seconds.
oGAuth:ExpireNumSeconds := 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.)
oGAuth:SubEmailAddress := ""

//  ------------------------------------------------------------------------
//  Set the IAT using the date/time from the NIST time server.
nUnixTime := oDt:GetAsUnixTime(0)
? "unixTime = " + Str(nUnixTime)
oGAuth:Iat := nUnixTime

//  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.
oTlsSock := CreateObject("Chilkat.Socket")
nSuccess := oTlsSock:Connect("www.googleapis.com", 443, 1, 5000)
IF (nSuccess != 1)
    ? oTlsSock:LastErrorText
    oSocket:destroy()
    oDt:destroy()
    oFac:destroy()
    oGAuth:destroy()
    oTlsSock:destroy()
    RETURN
ENDIF

//  Send the request to obtain the access token.
nSuccess := oGAuth:ObtainAccessToken(oTlsSock)
IF (nSuccess != 1)
    ? oGAuth:LastErrorText
    oSocket:destroy()
    oDt:destroy()
    oFac:destroy()
    oGAuth:destroy()
    oTlsSock:destroy()
    RETURN
ENDIF

//  Examine the access token:
? "Access Token: " + oGAuth:AccessToken

oSocket:destroy()
oDt:destroy()
oFac:destroy()
oGAuth:destroy()
oTlsSock:destroy()