X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Finbound_payment.rs;h=0c6d6f2b804bccd8cfb651c24995bf4959998a91;hb=ccf92157620da45032d75f06b5972eaf142c1ce3;hp=6e36cc1c0221dfbda1c424173d986cfa5b0f51db;hpb=5824e226cad67e32d5e8be71ebbb6f91a3fc2116;p=rust-lightning diff --git a/lightning/src/ln/inbound_payment.rs b/lightning/src/ln/inbound_payment.rs index 6e36cc1c..0c6d6f2b 100644 --- a/lightning/src/ln/inbound_payment.rs +++ b/lightning/src/ln/inbound_payment.rs @@ -68,6 +68,8 @@ impl ExpandedKey { enum Method { LdkPaymentHash = 0, UserPaymentHash = 1, + LdkPaymentHashCustomFinalCltv = 2, + UserPaymentHashCustomFinalCltv = 3, } impl Method { @@ -75,11 +77,18 @@ impl Method { match bits { bits if bits == Method::LdkPaymentHash as u8 => Ok(Method::LdkPaymentHash), bits if bits == Method::UserPaymentHash as u8 => Ok(Method::UserPaymentHash), + bits if bits == Method::LdkPaymentHashCustomFinalCltv as u8 => Ok(Method::LdkPaymentHashCustomFinalCltv), + bits if bits == Method::UserPaymentHashCustomFinalCltv as u8 => Ok(Method::UserPaymentHashCustomFinalCltv), unknown => Err(unknown), } } } +fn min_final_cltv_expiry_delta_from_metadata(bytes: [u8; METADATA_LEN]) -> u16 { + let expiry_bytes = &bytes[AMT_MSAT_LEN..]; + u16::from_be_bytes([expiry_bytes[0], expiry_bytes[1]]) +} + /// Equivalent to [`crate::ln::channelmanager::ChannelManager::create_inbound_payment`], but no /// `ChannelManager` is required. Useful for generating invoices for [phantom node payments] without /// a `ChannelManager`. @@ -90,15 +99,24 @@ impl Method { /// /// `current_time` is a Unix timestamp representing the current time. /// +/// Note that if `min_final_cltv_expiry_delta` is set to some value, then the payment will not be receivable +/// on versions of LDK prior to 0.0.114. +/// /// [phantom node payments]: crate::chain::keysinterface::PhantomKeysManager /// [`NodeSigner::get_inbound_payment_key_material`]: crate::chain::keysinterface::NodeSigner::get_inbound_payment_key_material -pub fn create(keys: &ExpandedKey, min_value_msat: Option, invoice_expiry_delta_secs: u32, keys_manager: &K, current_time: u64) -> Result<(PaymentHash, PaymentSecret), ()> - where K::Target: EntropySource +pub fn create(keys: &ExpandedKey, min_value_msat: Option, + invoice_expiry_delta_secs: u32, entropy_source: &ES, current_time: u64, + min_final_cltv_expiry_delta: Option) -> Result<(PaymentHash, PaymentSecret), ()> + where ES::Target: EntropySource { - let metadata_bytes = construct_metadata_bytes(min_value_msat, Method::LdkPaymentHash, invoice_expiry_delta_secs, current_time)?; + let metadata_bytes = construct_metadata_bytes(min_value_msat, if min_final_cltv_expiry_delta.is_some() { + Method::LdkPaymentHashCustomFinalCltv + } else { + Method::LdkPaymentHash + }, invoice_expiry_delta_secs, current_time, min_final_cltv_expiry_delta)?; let mut iv_bytes = [0 as u8; IV_LEN]; - let rand_bytes = keys_manager.get_secure_random_bytes(); + let rand_bytes = entropy_source.get_secure_random_bytes(); iv_bytes.copy_from_slice(&rand_bytes[..IV_LEN]); let mut hmac = HmacEngine::::new(&keys.ldk_pmt_hash_key); @@ -117,9 +135,17 @@ pub fn create(keys: &ExpandedKey, min_value_msat: Option, invoice /// /// See [`create`] for information on the `keys` and `current_time` parameters. /// +/// Note that if `min_final_cltv_expiry_delta` is set to some value, then the payment will not be receivable +/// on versions of LDK prior to 0.0.114. +/// /// [phantom node payments]: crate::chain::keysinterface::PhantomKeysManager -pub fn create_from_hash(keys: &ExpandedKey, min_value_msat: Option, payment_hash: PaymentHash, invoice_expiry_delta_secs: u32, current_time: u64) -> Result { - let metadata_bytes = construct_metadata_bytes(min_value_msat, Method::UserPaymentHash, invoice_expiry_delta_secs, current_time)?; +pub fn create_from_hash(keys: &ExpandedKey, min_value_msat: Option, payment_hash: PaymentHash, + invoice_expiry_delta_secs: u32, current_time: u64, min_final_cltv_expiry_delta: Option) -> Result { + let metadata_bytes = construct_metadata_bytes(min_value_msat, if min_final_cltv_expiry_delta.is_some() { + Method::UserPaymentHashCustomFinalCltv + } else { + Method::UserPaymentHash + }, invoice_expiry_delta_secs, current_time, min_final_cltv_expiry_delta)?; let mut hmac = HmacEngine::::new(&keys.user_pmt_hash_key); hmac.input(&metadata_bytes); @@ -132,7 +158,8 @@ pub fn create_from_hash(keys: &ExpandedKey, min_value_msat: Option, payment Ok(construct_payment_secret(&iv_bytes, &metadata_bytes, &keys.metadata_key)) } -fn construct_metadata_bytes(min_value_msat: Option, payment_type: Method, invoice_expiry_delta_secs: u32, highest_seen_timestamp: u64) -> Result<[u8; METADATA_LEN], ()> { +fn construct_metadata_bytes(min_value_msat: Option, payment_type: Method, + invoice_expiry_delta_secs: u32, highest_seen_timestamp: u64, min_final_cltv_expiry_delta: Option) -> Result<[u8; METADATA_LEN], ()> { if min_value_msat.is_some() && min_value_msat.unwrap() > MAX_VALUE_MSAT { return Err(()); } @@ -148,9 +175,27 @@ fn construct_metadata_bytes(min_value_msat: Option, payment_type: Method, i // than two hours in the future. Thus, we add two hours here as a buffer to ensure we // absolutely never fail a payment too early. // Note that we assume that received blocks have reasonably up-to-date timestamps. - let expiry_bytes = (highest_seen_timestamp + invoice_expiry_delta_secs as u64 + 7200).to_be_bytes(); + let expiry_timestamp = highest_seen_timestamp + invoice_expiry_delta_secs as u64 + 7200; + let mut expiry_bytes = expiry_timestamp.to_be_bytes(); + + // `min_value_msat` should fit in (64 bits - 3 payment type bits =) 61 bits as an unsigned integer. + // This should leave us with a maximum value greater than the 21M BTC supply cap anyway. + if min_value_msat.is_some() && min_value_msat.unwrap() > ((1u64 << 61) - 1) { return Err(()); } + + // `expiry_timestamp` should fit in (64 bits - 2 delta bytes =) 48 bits as an unsigned integer. + // Bitcoin's block header timestamps are actually `u32`s, so we're technically already limited to + // the much smaller maximum timestamp of `u32::MAX` for now, but we check the u64 `expiry_timestamp` + // for future-proofing. + if min_final_cltv_expiry_delta.is_some() && expiry_timestamp > ((1u64 << 48) - 1) { return Err(()); } + + if let Some(min_final_cltv_expiry_delta) = min_final_cltv_expiry_delta { + let bytes = min_final_cltv_expiry_delta.to_be_bytes(); + expiry_bytes[0] |= bytes[0]; + expiry_bytes[1] |= bytes[1]; + } let mut metadata_bytes: [u8; METADATA_LEN] = [0; METADATA_LEN]; + metadata_bytes[..AMT_MSAT_LEN].copy_from_slice(&min_amt_msat_bytes); metadata_bytes[AMT_MSAT_LEN..].copy_from_slice(&expiry_bytes); @@ -175,9 +220,13 @@ fn construct_payment_secret(iv_bytes: &[u8; IV_LEN], metadata_bytes: &[u8; METAD /// secret (and, if supplied by LDK, our payment preimage) to include encrypted metadata about the /// payment. /// -/// The metadata is constructed as: +/// For payments without a custom `min_final_cltv_expiry_delta`, the metadata is constructed as: /// payment method (3 bits) || payment amount (8 bytes - 3 bits) || expiry (8 bytes) -/// and encrypted using a key derived from [`NodeSigner::get_inbound_payment_key_material`]. +/// +/// For payments including a custom `min_final_cltv_expiry_delta`, the metadata is constructed as: +/// payment method (3 bits) || payment amount (8 bytes - 3 bits) || min_final_cltv_expiry_delta (2 bytes) || expiry (6 bytes) +/// +/// In both cases the result is then encrypted using a key derived from [`NodeSigner::get_inbound_payment_key_material`]. /// /// Then on payment receipt, we verify in this method that the payment preimage and payment secret /// match what was constructed. @@ -201,24 +250,27 @@ fn construct_payment_secret(iv_bytes: &[u8; IV_LEN], metadata_bytes: &[u8; METAD /// [`NodeSigner::get_inbound_payment_key_material`]: crate::chain::keysinterface::NodeSigner::get_inbound_payment_key_material /// [`create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment /// [`create_inbound_payment_for_hash`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash -pub(super) fn verify(payment_hash: PaymentHash, payment_data: &msgs::FinalOnionHopData, highest_seen_timestamp: u64, keys: &ExpandedKey, logger: &L) -> Result, ()> +pub(super) fn verify(payment_hash: PaymentHash, payment_data: &msgs::FinalOnionHopData, + highest_seen_timestamp: u64, keys: &ExpandedKey, logger: &L) -> Result< + (Option, Option), ()> where L::Target: Logger { let (iv_bytes, metadata_bytes) = decrypt_metadata(payment_data.payment_secret, keys); let payment_type_res = Method::from_bits((metadata_bytes[0] & 0b1110_0000) >> METHOD_TYPE_OFFSET); let mut amt_msat_bytes = [0; AMT_MSAT_LEN]; + let mut expiry_bytes = [0; METADATA_LEN - AMT_MSAT_LEN]; amt_msat_bytes.copy_from_slice(&metadata_bytes[..AMT_MSAT_LEN]); + expiry_bytes.copy_from_slice(&metadata_bytes[AMT_MSAT_LEN..]); // Zero out the bits reserved to indicate the payment type. amt_msat_bytes[0] &= 0b00011111; - let min_amt_msat: u64 = u64::from_be_bytes(amt_msat_bytes.into()); - let expiry = u64::from_be_bytes(metadata_bytes[AMT_MSAT_LEN..].try_into().unwrap()); + let mut min_final_cltv_expiry_delta = None; - // Make sure to check to check the HMAC before doing the other checks below, to mitigate timing - // attacks. + // Make sure to check the HMAC before doing the other checks below, to mitigate timing attacks. let mut payment_preimage = None; + match payment_type_res { - Ok(Method::UserPaymentHash) => { + Ok(Method::UserPaymentHash) | Ok(Method::UserPaymentHashCustomFinalCltv) => { let mut hmac = HmacEngine::::new(&keys.user_pmt_hash_key); hmac.input(&metadata_bytes[..]); hmac.input(&payment_hash.0); @@ -227,7 +279,7 @@ pub(super) fn verify(payment_hash: PaymentHash, payment_data: &msgs::F return Err(()) } }, - Ok(Method::LdkPaymentHash) => { + Ok(Method::LdkPaymentHash) | Ok(Method::LdkPaymentHashCustomFinalCltv) => { match derive_ldk_payment_preimage(payment_hash, &iv_bytes, &metadata_bytes, keys) { Ok(preimage) => payment_preimage = Some(preimage), Err(bad_preimage_bytes) => { @@ -242,6 +294,19 @@ pub(super) fn verify(payment_hash: PaymentHash, payment_data: &msgs::F } } + match payment_type_res { + Ok(Method::UserPaymentHashCustomFinalCltv) | Ok(Method::LdkPaymentHashCustomFinalCltv) => { + min_final_cltv_expiry_delta = Some(min_final_cltv_expiry_delta_from_metadata(metadata_bytes)); + // Zero out first two bytes of expiry reserved for `min_final_cltv_expiry_delta`. + expiry_bytes[0] &= 0; + expiry_bytes[1] &= 0; + } + _ => {} + } + + let min_amt_msat: u64 = u64::from_be_bytes(amt_msat_bytes.into()); + let expiry = u64::from_be_bytes(expiry_bytes.try_into().unwrap()); + if payment_data.total_msat < min_amt_msat { log_trace!(logger, "Failing HTLC with payment_hash {} due to total_msat {} being less than the minimum amount of {} msat", log_bytes!(payment_hash.0), payment_data.total_msat, min_amt_msat); return Err(()) @@ -252,20 +317,20 @@ pub(super) fn verify(payment_hash: PaymentHash, payment_data: &msgs::F return Err(()) } - Ok(payment_preimage) + Ok((payment_preimage, min_final_cltv_expiry_delta)) } pub(super) fn get_payment_preimage(payment_hash: PaymentHash, payment_secret: PaymentSecret, keys: &ExpandedKey) -> Result { let (iv_bytes, metadata_bytes) = decrypt_metadata(payment_secret, keys); match Method::from_bits((metadata_bytes[0] & 0b1110_0000) >> METHOD_TYPE_OFFSET) { - Ok(Method::LdkPaymentHash) => { + Ok(Method::LdkPaymentHash) | Ok(Method::LdkPaymentHashCustomFinalCltv) => { derive_ldk_payment_preimage(payment_hash, &iv_bytes, &metadata_bytes, keys) .map_err(|bad_preimage_bytes| APIError::APIMisuseError { err: format!("Payment hash {} did not match decoded preimage {}", log_bytes!(payment_hash.0), log_bytes!(bad_preimage_bytes)) }) }, - Ok(Method::UserPaymentHash) => Err(APIError::APIMisuseError { + Ok(Method::UserPaymentHash) | Ok(Method::UserPaymentHashCustomFinalCltv) => Err(APIError::APIMisuseError { err: "Expected payment type to be LdkPaymentHash, instead got UserPaymentHash".to_string() }), Err(other) => Err(APIError::APIMisuseError { err: format!("Unknown payment type: {}", other) }),