Using Email Yak To Provide Bidirectional Email Communication In Your Web Applications

<cffunction
	name="toHexDigest"
	access="public"
	returntype="any"
	output="false"
	hint="I take the given API key and the POST BODY and return the HEX digest for request authentication.">

	<!--- Define arguments. --->
	<cfargument
		name="apiKey"
		type="string"
		required="true"
		hint="I am the Email Yak API key."
		/>

	<cfargument
		name="content"
		type="string"
		required="true"
		hint="I am the string content of the post that we are verifying."
		/>

	<!--- Define the local scope. --->
	<cfset var local = {} />

	<!---
		We need to hash the body of the post using the MD5 algorithm.
		Let's define a key specification using the Email Yak API key.
	--->
	<cfset local.secretKeySpec = createObject( "java", "javax.crypto.spec.SecretKeySpec" ).init(
		toBinary( toBase64( arguments.apiKey ) ),
		javaCast( "string", "HmacMD5" )
		) />

	<!---
		Now, let's create our MAC (Message Authentication Code)
		generator to hash the actual email post content.
	--->
	<cfset local.mac = createObject( "java", "javax.crypto.Mac" ).getInstance(
		javaCast( "string", "HmacMD5" )
		) />

	<!--- Initialize the MAC using our secret key. --->
	<cfset local.mac.init( local.secretKeySpec ) />

	<!--- Hash the content. --->
	<cfset local.hashedBytes = local.mac.doFinal(
		toBinary( toBase64( arguments.content ) )
		) />

	<!---
		Now we need to convert the bytes to a HEX string. We will
		need to convert each byte individually, so create a buffer
		to hold each HEX character.
	--->
	<cfset local.hexBuffer = [] />

	<!--- Loop over each byte. --->
	<cfloop
		index="local.byte"
		array="#local.hashedBytes#">

		<!---
			Get the HEX value. If a value comes through with a
			negative number, it will be "padded" with "F"
			characters. As such, let's make sure to only get the
			right-most 2 bits of the underlying byte.

			NOTE: We're using 255 insetad of 256 because we are
			using signed integers.
		--->
		<cfset local.hexChar = formatBaseN(
			bitAnd( local.byte, 255 ),
			16
			) />

		<!---
			When appending, make sure the HEX value has 2 digits.
			The conversion will cut off the leading zero for values
			less that 10.
		--->
		<cfif (len( local.hexChar ) eq 1)>

			<!--- Prepend the padding zero. --->
			<cfset local.hexChar = ("0" & local.hexChar) />

		</cfif>

		<!--- Append 2-digit hex value. --->
		<cfset arrayAppend( local.hexBuffer, local.hexChar ) />

	</cfloop>

	<!--- Return the HEX digetst of the content. --->
	<cfreturn arrayToList( local.hexBuffer, "" ) />
</cffunction>



<!--- ----------------------------------------------------- --->
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<!--- Define a log file for local CFDump'ing. --->
<cfset logFile = (
	getDirectoryFromPath( getCurrentTemplatePath() ) &
	"log.htm"
	) />

<!---
	Define the base API url. All Email Yak resources will be based
	off of this value.
--->
<cfset apiUrl = "https://api.emailyak.com/v1/#application.apiKey#" />


<!---
	Since we are dealing with an POST that may not be from a known
	source, let's wrap the processing in a Try/Catch where we can
	handle errors more appropriately.
--->
<cftry>


	<!--- Get a reference to the post headers. --->
	<cfset httpHeaders = getHttpRequestData().headers />


	<!--- Make sure the Email Yak auth key exists. --->
	<cfif !structKeyExists( httpHeaders, "X-Emailyak-Post-Auth" )>

		<!--- We can't authorize with out the right headers. --->
		<cfthrow
			type="NotAuthorized"
			message="Authorization failed."
			detail="Request cannot be authorized without the [X-Emailyak-Post-Auth] HTTP request header."
			/>

	</cfif>

	<!--- Get the secure digest of the content using our API key. --->
	<cfset hexDigest = toHexDigest(
		application.apiKey,
		toString( getHttpRequestData().content )
		) />

	<!--- Check to make sure the digests match. --->
	<cfif (httpHeaders[ "X-Emailyak-Post-Auth" ] neq hexDigest)>

		<!--- The digest does not match - source may be malicious. --->
		<cfthrow
			type="NotAuthorized"
			message="Authorization failed."
			detail="The provided message digest did not match the calculated digest."
			/>

	</cfif>


	<!--- Check to make sure the content is valid JSON. --->
	<cfif !isJSON( toString( getHttpRequestData().content ) )>

		<!--- Can't process this data. --->
		<cfthrow
			type="BadRequest"
			message="Request content must be valid JSON."
			detail="The content of the post was not valid JSON."
			/>

	</cfif>


	<!--- Parse the JSON content. --->
	<cfset email = deserializeJSON(
		toString( getHttpRequestData().content )
		) />


	<!--- Log the email data that came through. --->
	<cfdump
		var="#email#"
		output="#logFile#"
		hide="Headers"
		format="html"
		label="Email Yak Data"
		/>


	<!---
		Now that we have an email, let's see if we can respond to
		the user and echo back what they said. Since the given email
		may have many parsed parts, we'll echo back only the first
		part of the series.
	--->

	<!--- Create the email post. --->
	<cfset emailPost = {} />

	<!---
		Use a new or registered address. If the email is not yet
		registered, it will automatically be registered and can then
		be used to receive emails.
	--->
	<cfset emailPost[ "FromAddress" ] = "ben@bennadel.simpleyak.com" />

	<!--- Set the from name. --->
	<cfset emailPost[ "FromName" ] = "Benny Yak" />

	<!---
		When sending, send back to the user who sent the incoming
		email message.
	--->
	<cfset emailPost[ "ToAddress" ] = email.fromAddress />

	<!--- Set the subject. --->
	<cfset emailPost[ "Subject" ] = "Thanks for contacting us!" />

	<!---
		Define the post property names first, so we can maintain
		case. We'll define the actual content using a content buffer.
	--->
	<cfset emailPost[ "HtmlBody" ] = "" />
	<cfset emailPost[ "TextBody" ] = "Update your email client!" />

	<!--- Define the HTML. --->
	<cfsavecontent variable="emailPost.HtmlBody">
		<cfoutput>

			Thanks for contact us!<br />
			<br />

			We have added the following message to our system:<br />
			<br />

			<hr />

			<!--- Echo back the content that was received. --->
			<pre>#htmlEditFormat( email.parsedData[ 1 ].data )#</pre>

		</cfoutput>
	</cfsavecontent>


	<!---
		Send out the email using the Email Yak API. Notice that we
		must post the content as JSON and that the API URL includes
		the API key as part of the resource definition.
	--->
	<cfhttp
		result="apiResponse"
		method="post"
		url="#apiUrl#/json/send/email/">

		<!--- Set the content type to be JSON. --->
		<cfhttpparam
			type="header"
			name="content-type"
			value="application/json; charset=utf-8"
			/>

		<!--- Specify that we can accept JSON as well. --->
		<cfhttpparam
			type="header"
			name="accept"
			value="application/json; charset=utf-8"
			/>

		<!--- Post the email. --->
		<cfhttpparam
			type="body"
			value="#serializeJSON( emailPost )#"
			/>

	</cfhttp>


	<!--- Log the response. --->
	<cfdump
		var="#deserializeJSON( toString( apiResponse.fileContent ) )#"
		output="#logFile#"
		format="html"
		label="API Response"
		/>


	<!--- ------------------------------------------------- --->
	<!--- ------------------------------------------------- --->


	<!--- Catch any unspecified errors. --->
	<cfcatch>

		<!--- Log exception. --->
		<cfdump
			var="#cfcatch#"
			output="#logFile#"
			format="html"
			label="CFCATCH - Unexpected Exception"
			/>

	</cfcatch>

</cftry>