f ensure we validate total output amount against max bitcoin supply

Author: jurvis

lightning/src/ln/interactivetxs.rs

@@ -107,7 +107,7 @@ impl NegotiationContext {
 		self.outputs
 			.iter()
 			.filter(move |(serial_id, _)| self.is_serial_id_valid_for_counterparty(serial_id))
-			.map(|(_, input_with_prevout)| input_with_prevout)
+			.map(|(_, output)| output)
 	}
 
 	fn received_tx_add_input(&mut self, msg: &msgs::TxAddInput) -> Result<(), AbortReason> {
@@ -147,7 +147,9 @@ impl NegotiationContext {
 				//  - MUST fail the negotiation if:
 				//     - the `scriptPubKey` is not a witness program
 				return Err(AbortReason::PrevTxOutInvalid);
-			} else if !self.prevtx_outpoints.insert(OutPoint { txid, vout: msg.prevtx_out }) {
+			}
+
+			if !self.prevtx_outpoints.insert(OutPoint { txid, vout: msg.prevtx_out }) {
 				// The receiving node:
 				//  - MUST fail the negotiation if:
 				//     - the `prevtx` and `prevtx_vout` are identical to a previously added
@@ -173,17 +175,14 @@ impl NegotiationContext {
 			return Err(AbortReason::DuplicateSerialId);
 		}
 		let prev_outpoint = OutPoint { txid, vout: msg.prevtx_out };
-		self.inputs.insert(
-			msg.serial_id,
-			TxInputWithPrevOutput {
-				input: TxIn {
-					previous_output: prev_outpoint.clone(),
-					sequence: Sequence(msg.sequence),
-					..Default::default()
-				},
-				prev_output: prev_out,
+		self.inputs.entry(msg.serial_id).or_insert_with(|| TxInputWithPrevOutput {
+			input: TxIn {
+				previous_output: prev_outpoint.clone(),
+				sequence: Sequence(msg.sequence),
+				..Default::default()
 			},
-		);
+			prev_output: prev_out,
+		});
 		self.prevtx_outpoints.insert(prev_outpoint);
 		Ok(())
 	}
@@ -193,15 +192,14 @@ impl NegotiationContext {
 			return Err(AbortReason::IncorrectSerialIdParity);
 		}
 
-		if let Some(_) = self.inputs.remove(&msg.serial_id) {
-			Ok(())
-		} else {
+		self.inputs
+			.remove(&msg.serial_id)
 			// The receiving node:
 			//  - MUST fail the negotiation if:
 			//    - the input or output identified by the `serial_id` was not added by the sender
 			//    - the `serial_id` does not correspond to a currently added input
-			Err(AbortReason::SerialIdUnknown)
-		}
+			.ok_or(AbortReason::SerialIdUnknown)
+			.map(|_| ())
 	}
 
 	fn received_tx_add_output(&mut self, msg: &msgs::TxAddOutput) -> Result<(), AbortReason> {
@@ -226,7 +224,14 @@ impl NegotiationContext {
 			//		- the sats amount is less than the dust_limit
 			return Err(AbortReason::BelowDustLimit);
 		}
-		if msg.sats > TOTAL_BITCOIN_SUPPLY_SATOSHIS {
+
+		// Check that adding this output would not cause the total output value to exceed the total
+		// bitcoin supply.
+		let mut outputs_value: u64 = 0;
+		for output in self.outputs.iter() {
+			outputs_value = outputs_value.saturating_add(output.1.value);
+		}
+		if outputs_value.saturating_add(msg.sats) > TOTAL_BITCOIN_SUPPLY_SATOSHIS {
 			// The receiving node:
 			// - MUST fail the negotiation if:
 			//		- the sats amount is greater than 2,100,000,000,000,000 (TOTAL_BITCOIN_SUPPLY_SATOSHIS)
@@ -257,7 +262,7 @@ impl NegotiationContext {
 		}
 
 		let output = TxOut { value: msg.sats, script_pubkey: msg.script.clone() };
-		self.outputs.insert(msg.serial_id, output);
+		self.outputs.entry(msg.serial_id).or_insert(output);
 		Ok(())
 	}