From 6368b9383a8687677c44f0dfff13ee0e10cddd2c Mon Sep 17 00:00:00 2001
From: Moxie Marlinspike <moxie@thoughtcrime.org>
Date: Tue, 3 Nov 2015 08:12:18 -0800
Subject: [PATCH] Stripe SMS/Vox across multiple numbers

// FREEBIE
---
 .../configuration/TwilioConfiguration.java    | 11 +++++----
 .../textsecuregcm/sms/TwilioSmsSender.java    | 23 +++++++++++++------
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/src/main/java/org/whispersystems/textsecuregcm/configuration/TwilioConfiguration.java b/src/main/java/org/whispersystems/textsecuregcm/configuration/TwilioConfiguration.java
index bba847b84..c65e4fd3d 100644
--- a/src/main/java/org/whispersystems/textsecuregcm/configuration/TwilioConfiguration.java
+++ b/src/main/java/org/whispersystems/textsecuregcm/configuration/TwilioConfiguration.java
@@ -19,6 +19,9 @@ package org.whispersystems.textsecuregcm.configuration;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import org.hibernate.validator.constraints.NotEmpty;
 
+import javax.validation.constraints.NotNull;
+import java.util.List;
+
 public class TwilioConfiguration {
 
   @NotEmpty
@@ -29,9 +32,9 @@ public class TwilioConfiguration {
   @JsonProperty
   private String accountToken;
 
-  @NotEmpty
+  @NotNull
   @JsonProperty
-  private String number;
+  private List<String> numbers;
 
   @NotEmpty
   @JsonProperty
@@ -48,8 +51,8 @@ public class TwilioConfiguration {
     return accountToken;
   }
 
-  public String getNumber() {
-    return number;
+  public List<String> getNumbers() {
+    return numbers;
   }
 
   public String getLocalDomain() {
diff --git a/src/main/java/org/whispersystems/textsecuregcm/sms/TwilioSmsSender.java b/src/main/java/org/whispersystems/textsecuregcm/sms/TwilioSmsSender.java
index 1f60ae003..efe636bcf 100644
--- a/src/main/java/org/whispersystems/textsecuregcm/sms/TwilioSmsSender.java
+++ b/src/main/java/org/whispersystems/textsecuregcm/sms/TwilioSmsSender.java
@@ -29,10 +29,12 @@ import org.whispersystems.textsecuregcm.configuration.TwilioConfiguration;
 import org.whispersystems.textsecuregcm.util.Constants;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Random;
 
 import static com.codahale.metrics.MetricRegistry.name;
 
@@ -47,16 +49,18 @@ public class TwilioSmsSender {
   private final Meter          smsMeter       = metricRegistry.meter(name(getClass(), "sms", "delivered"));
   private final Meter          voxMeter       = metricRegistry.meter(name(getClass(), "vox", "delivered"));
 
-  private final String accountId;
-  private final String accountToken;
-  private final String number;
-  private final String localDomain;
+  private final String            accountId;
+  private final String            accountToken;
+  private final ArrayList<String> numbers;
+  private final String            localDomain;
+  private final Random            random;
 
   public TwilioSmsSender(TwilioConfiguration config) {
     this.accountId    = config.getAccountId();
     this.accountToken = config.getAccountToken();
-    this.number       = config.getNumber();
+    this.numbers      = new ArrayList<>(config.getNumbers());
     this.localDomain  = config.getLocalDomain();
+    this.random       = new Random(System.currentTimeMillis());
   }
 
   public void deliverSmsVerification(String destination, String verificationCode)
@@ -66,7 +70,7 @@ public class TwilioSmsSender {
     MessageFactory      messageFactory = client.getAccount().getMessageFactory();
     List<NameValuePair> messageParams  = new LinkedList<>();
     messageParams.add(new BasicNameValuePair("To", destination));
-    messageParams.add(new BasicNameValuePair("From", number));
+    messageParams.add(new BasicNameValuePair("From", getRandom(random, numbers)));
     messageParams.add(new BasicNameValuePair("Body", SmsSender.SMS_VERIFICATION_TEXT + verificationCode));
 
     try {
@@ -85,7 +89,7 @@ public class TwilioSmsSender {
     CallFactory         callFactory = client.getAccount().getCallFactory();
     Map<String, String> callParams  = new HashMap<>();
     callParams.put("To", destination);
-    callParams.put("From", number);
+    callParams.put("From", getRandom(random, numbers));
     callParams.put("Url", "https://" + localDomain + "/v1/accounts/voice/twiml/" + verificationCode);
 
     try {
@@ -96,4 +100,9 @@ public class TwilioSmsSender {
 
     voxMeter.mark();
   }
+
+  private String getRandom(Random random, ArrayList<String> elements) {
+    return elements.get(random.nextInt(elements.size()));
+  }
+
 }