SMS retrieval API in android

Akshay Kumar

29 July 2022

In this blog, we going to discuss the SMS retrieval API in android.

SMS retrieval API is used for SMS-based verification without writing the verification code manually.

When we integrate the mobile verification feature in our application and we want to do the verification using the OTP received on our mobile without entering the OTP then this blog is for you.

The above mention verification will work on the below sequence:

A user initiates the request for the verification of the mobile number to your server.
Now the server processes the number and checks for its existence.
The server sends the message to the mobile number. The message contains the verification code and the hash code that identify your app.
Your device receives the message and Google play services determine the message for your application by using the hash code. Google play services provide the message content to your application
Your application parse the message content and get the verification code from the message content.
verification code is now shared with your server for verification.
The server verifies the code and does the needful.

Initial setup

Add the Gradle dependency to your app/module build.gradle file like below:

api 'com.google.android.gms:play-services-auth:20.2.0'
api 'com.google.android.gms:play-services-auth-api-phone:18.0.1'

1 2	api 'com.google.android.gms:play-services-auth:20.2.0' api 'com.google.android.gms:play-services-auth-api-phone:18.0.1'

Start SMS retriever

Start the SMS retriever by the SMSRetriever client like below:

private fun setupSMSRetriever() {
        val client = SmsRetriever.getClient(mFragmentContext.activity!!)
        val task = client.startSmsRetriever()
        task.addOnSuccessListener {
            Log.d("DEBUG", "SMS retriever is working now")
            MySmsListener.bindListener(mFragmentContext!!)
        }

        task.addOnFailureListener {
            Log.d("DEBUG", "SMS retriever is not working")
        }
    }

private fun setupSMSRetriever() {

val client = SmsRetriever.getClient(mFragmentContext.activity!!)

val task = client.startSmsRetriever()

task.addOnSuccessListener {

Log.d("DEBUG", "SMS retriever is working now")

MySmsListener.bindListener(mFragmentContext!!)

}

task.addOnFailureListener {

Log.d("DEBUG", "SMS retriever is not working")

}

Get verification message

Our MySmsListener class is extending the BroadcastReceiver and inside the onReceive we are receiving the SMS contents.

class MySmsListener : BroadcastReceiver() { override fun onReceive(context: Context, intent: Intent) { if (SmsRetriever.SMS_RETRIEVED_ACTION == intent.action) { val extras = intent.extras if (extras != null) { val status = extras.get(SmsRetriever.EXTRA_STATUS) as Status when (status.statusCode) { CommonStatusCodes.SUCCESS -> { mListener!!.messageReceived(extras.get(SmsRetriever.EXTRA_SMS_MESSAGE) as String) } CommonStatusCodes.TIMEOUT -> { } } } } else { Log.d("SMS: ", intent.action.toString()) } } companion object { private var mListener: MessageListener? = null fun bindListener(listener: MessageListener) { mListener = listener } } }

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class MySmsListener : BroadcastReceiver() {

    override fun onReceive(context: Context, intent: Intent) {
        if (SmsRetriever.SMS_RETRIEVED_ACTION == intent.action) {
            val extras = intent.extras
            if (extras != null) {
                val status = extras.get(SmsRetriever.EXTRA_STATUS) as Status

                when (status.statusCode) {
                    CommonStatusCodes.SUCCESS -> {
                        mListener!!.messageReceived(extras.get(SmsRetriever.EXTRA_SMS_MESSAGE) as String)

                    }
                    CommonStatusCodes.TIMEOUT -> {

                    }

                }
            }
        } else {
            Log.d("SMS: ", intent.action.toString())

        }
    }

    companion object {

        private var mListener: MessageListener? = null

        fun bindListener(listener: MessageListener) {
            mListener = listener
        }
    }
}

<receiver android:name=".helpers.SmsListener" android:exported="true">
            <intent-filter>
                <action android:name="com.google.android.gms.auth.api.phone.SMS_RETRIEVED"/>
            </intent-filter>
        </receiver>

<intent-filter>

</intent-filter>

</receiver>

Also we have created MessageListener for sending the message data to our activity like below:

public interface MessageListener {
    void messageReceived(String message);
}

public interface MessageListener {

void messageReceived(String message);

}

As we are using the messageListener interface to pass data to our activity you need to extend the interface like below:

class LoginActivity : AppCompatActivity(), MessageListener {}

1	class LoginActivity : AppCompatActivity(), MessageListener {}

Once we have extended the interface now override the messageReceived() like below:

override fun messageReceived(message: String?) {
        if (message != null) {
            var otpRegx = ""
            for (i in 0 until AppSharedPref.getTwilioOtpLength(context!!)!!.toInt()) {
                otpRegx += "\\d"
            }
            val m = Pattern.compile(otpRegx).matcher(message)
            while (m.find()) {
                mContentViewBinding.otpEt.setText(m.group().trim())
                break
            }
        }
    }

override fun messageReceived(message: String?) {

if (message != null) {

var otpRegx = ""

for (i in 0 until AppSharedPref.getTwilioOtpLength(context!!)!!.toInt()) {

otpRegx += "\\d"

}

val m = Pattern.compile(otpRegx).matcher(message)

while (m.find()) {

mContentViewBinding.otpEt.setText(m.group().trim())

break

}

When the data is received update your view accordingly. Also, pass the data to the server for verification.

Once the server receive the mobile number for verification the verification message for the mobile number must have the below format:

Your OTP For Login : 1534

w34CwYs+zyo

Your OTP For Login : 1534

w34CwYs+zyo

Get SMS retrieval hash

For generating the above mentioned hash code(w34CwYs+zyo) for your application so that the play services will determine that the received message is for your app follow the link.

Conclusion:

In this blog, we have learned about the implementation of the SMS retrieval API in android.

For more information regarding the SMS retrieval API in android follow the link.

Thanks for reading this blog. You can also check other blogs from here.