Drop non-matching custom TLVs when receiving MPP

[rust-lightning] / lightning / src / ln / outbound_payment.rs

diff --git a/lightning/src/ln/outbound_payment.rs b/lightning/src/ln/outbound_payment.rs
index 0e3c15c80669965e6523460afa735ee28cdfa99f..9c8d66458739d7e21f2982ea50e096a7013fb98f 100644 (file)
--- a/lightning/src/ln/outbound_payment.rs
+++ b/lightning/src/ln/outbound_payment.rs
@@ -511,7 +511,17 @@ impl RecipientOnionFields {
        pub(super) fn check_merge(&mut self, further_htlc_fields: &mut Self) -> Result<(), ()> {
                if self.payment_secret != further_htlc_fields.payment_secret { return Err(()); }
                if self.payment_metadata != further_htlc_fields.payment_metadata { return Err(()); }
-               // For custom TLVs we should just drop non-matching ones, but not reject the payment.
+
+               let tlvs = &mut self.custom_tlvs;
+               let further_tlvs = &mut further_htlc_fields.custom_tlvs;
+
+               let even_tlvs: Vec<&(u64, Vec<u8>)> = tlvs.iter().filter(|(typ, _)| *typ % 2 == 0).collect();
+               let further_even_tlvs: Vec<&(u64, Vec<u8>)> = further_tlvs.iter().filter(|(typ, _)| *typ % 2 == 0).collect();
+               if even_tlvs != further_even_tlvs { return Err(()) }
+
+               tlvs.retain(|tlv| further_tlvs.iter().any(|further_tlv| tlv == further_tlv));
+               further_tlvs.retain(|further_tlv| tlvs.iter().any(|tlv| tlv == further_tlv));
+
                Ok(())
        }
 }