From 4ca476ff353913b33034ff5e5a1f0c4d734d8c64 Mon Sep 17 00:00:00 2001
From: Simon de la Rouviere <simon@delarouviere.com>
Date: Mon, 20 Jan 2014 17:40:57 +0200
Subject: [PATCH] When throwing InsufficientMoneyException, the amount of
 satoshis missing is required. When the server requests too much value, it is
 stored so that implementations of the client has access to it.

---
 .../channels/PaymentChannelClient.java          | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/com/google/bitcoin/protocols/channels/PaymentChannelClient.java b/core/src/main/java/com/google/bitcoin/protocols/channels/PaymentChannelClient.java
index ba63119d..e08d1024 100644
--- a/core/src/main/java/com/google/bitcoin/protocols/channels/PaymentChannelClient.java
+++ b/core/src/main/java/com/google/bitcoin/protocols/channels/PaymentChannelClient.java
@@ -86,6 +86,9 @@ public class PaymentChannelClient implements IPaymentChannelClient {
     // Information used during channel initialization to send to the server or check what the server sends to us
     private final ECKey myKey;
     private final BigInteger maxValue;
+
+    private BigInteger missing;
+
     @GuardedBy("lock") private long minPayment;
 
     @GuardedBy("lock") SettableFuture<BigInteger> increasePaymentFuture;
@@ -127,6 +130,16 @@ public class PaymentChannelClient implements IPaymentChannelClient {
         this.conn = checkNotNull(conn);
     }
 
+    /** 
+     * <p>Returns the amount of satoshis missing when a server requests too much value.</p>
+     *
+     * <p>When InsufficientMoneyException is thrown due to the server requesting too much value, an instance of 
+     * PaymentChannelClient needs access to how many satoshis are missing.</p>
+     */
+    public BigInteger getMissing() {
+        return missing;
+    }
+
     @Nullable
     @GuardedBy("lock")
     private CloseReason receiveInitiate(Protos.Initiate initiate, BigInteger contractValue, Protos.Error.Builder errorBuilder) throws VerificationException, InsufficientMoneyException {
@@ -144,9 +157,10 @@ public class PaymentChannelClient implements IPaymentChannelClient {
         }
 
         BigInteger minChannelSize = BigInteger.valueOf(initiate.getMinAcceptedChannelSize());
-        if (maxValue.compareTo(minChannelSize) < 0) {
+        if (contractValue.compareTo(minChannelSize) < 0) {
             log.error("Server requested too much value");
             errorBuilder.setCode(Protos.Error.ErrorCode.CHANNEL_VALUE_TOO_LARGE);
+            missing = minChannelSize.subtract(contractValue);
             return CloseReason.SERVER_REQUESTED_TOO_MUCH_VALUE;
         }
 
@@ -157,6 +171,7 @@ public class PaymentChannelClient implements IPaymentChannelClient {
             log.error("Server requested a min payment of {} but we expected {}", initiate.getMinPayment(), MIN_PAYMENT);
             errorBuilder.setCode(Protos.Error.ErrorCode.MIN_PAYMENT_TOO_LARGE);
             errorBuilder.setExpectedValue(MIN_PAYMENT);
+            missing = BigInteger.valueOf(initiate.getMinPayment() - MIN_PAYMENT);
             return CloseReason.SERVER_REQUESTED_TOO_MUCH_VALUE;
         }