From a93803c9406e560af7a6046e08df179c391dd7ee Mon Sep 17 00:00:00 2001
From: Sonkeng Maldini <sdmg15@pm.me>
Date: Thu, 11 Dec 2025 15:52:19 +0100
Subject: [PATCH] add bip353 payment instructions support

---
 Cargo.toml                         |   2 +
 src/bip353_payment_instructions.rs | 131 +++++++++++++++++++++++++++++
 src/lib.rs                         |   3 +
 3 files changed, 136 insertions(+)
 create mode 100644 src/bip353_payment_instructions.rs

diff --git a/Cargo.toml b/Cargo.toml
index 27414e6..98ce1f6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,7 @@ readme = "README.md"
 [dependencies]
 miniscript = { version = "12", default-features = false }
 bdk_coin_select = "0.4.0"
+bitcoin-payment-instructions = { version = "0.5.0", optional = true}
 
 [dev-dependencies]
 anyhow = "1"
@@ -25,6 +26,7 @@ bdk_chain = { version = "0.23.0" }
 [features]
 default = ["std"]
 std = ["miniscript/std"]
+bip353 = ["bitcoin-payment-instructions"]
 
 [[example]]
 name = "synopsis"
diff --git a/src/bip353_payment_instructions.rs b/src/bip353_payment_instructions.rs
new file mode 100644
index 0000000..71da314
--- /dev/null
+++ b/src/bip353_payment_instructions.rs
@@ -0,0 +1,131 @@
+/// This crate adds support for BIP 353 DNS payment instructions support
+///
+use crate::bitcoin::{Amount, Network, ScriptBuf};
+use alloc::vec::Vec;
+use bitcoin_payment_instructions::{
+    amount, dns_resolver::DNSHrnResolver, hrn_resolution::HrnResolver,
+    FixedAmountPaymentInstructions, ParseError, PaymentInstructions, PaymentMethod,
+    PaymentMethodType,
+};
+use core::{net::SocketAddr, str::FromStr};
+
+async fn parse_dns_instructions(
+    hrn: &str,
+    resolver: &impl HrnResolver,
+    network: Network,
+) -> Result<PaymentInstructions, ParseError> {
+    let instructions = PaymentInstructions::parse(hrn, network, resolver, true).await?;
+
+    Ok(instructions)
+}
+
+pub struct Payment {
+    pub script: ScriptBuf,
+    pub amount: Amount,
+    pub dnssec_proof: Option<Vec<u8>>,
+}
+
+fn process_fixed_instructions(
+    amount: Amount,
+    instructions: &FixedAmountPaymentInstructions,
+) -> Result<Payment, ParseError> {
+    // Look for on chain payment method as it's the only one we can support
+    let PaymentMethod::OnChain(addr) = instructions
+        .methods()
+        .iter()
+        .find(|ix| matches!(ix, PaymentMethod::OnChain(_)))
+        .map(|pm| pm)
+        .unwrap()
+    else {
+        return Err(ParseError::InvalidInstructions(
+            "Unsupported payment method",
+        ));
+    };
+
+    let Some(onchain_amount) = instructions.onchain_payment_amount() else {
+        return Err(ParseError::InvalidInstructions(
+            "On chain amount should be specified",
+        ));
+    };
+
+    // We need this conversion since Amount from instructions is different from Amount from bitcoin
+    let onchain_amount = Amount::from_sat(onchain_amount.sats_rounding_up());
+
+    if onchain_amount != amount {
+        return Err(ParseError::InvalidInstructions(
+            "Mismatched amount expected , got",
+        ));
+    }
+
+    Ok(Payment {
+        script: addr.script_pubkey(),
+        amount: onchain_amount,
+        dnssec_proof: instructions.bip_353_dnssec_proof().clone(),
+    })
+}
+
+// If dns instructions provides a fixed amount we can allow the user not putting an amount?
+pub async fn resolve_dns_recipient(
+    hrn: &str,
+    amount: Amount,
+    network: Network,
+) -> Result<Payment, ParseError> {
+    let resolver = DNSHrnResolver(SocketAddr::from_str("8.8.8.8:53").expect("Should not fail."));
+    let payment_instructions = parse_dns_instructions(hrn, &resolver, network).await?;
+
+    match payment_instructions {
+        PaymentInstructions::ConfigurableAmount(instructions) => {
+            // Look for on chain payment method as it's the only one we can support
+            if instructions
+                .methods()
+                .find(|method| matches!(method.method_type(), PaymentMethodType::OnChain))
+                .is_none()
+            {
+                return Err(ParseError::InvalidInstructions(
+                    "Unsupported payment method",
+                ));
+            }
+
+            let min_amount = instructions.min_amt();
+            let max_amount = instructions.max_amt();
+
+            if min_amount.is_some() {
+                let min_amount = min_amount
+                    .map(|a| Amount::from_sat(a.sats_rounding_up()))
+                    .unwrap();
+                if amount < min_amount {
+                    return Err(ParseError::InvalidInstructions(
+                        "Amount lesser than min amount",
+                    ));
+                }
+            }
+
+            if max_amount.is_some() {
+                let max_amount = max_amount
+                    .map(|a| Amount::from_sat(a.sats_rounding_up()))
+                    .unwrap();
+                if amount > max_amount {
+                    return Err(ParseError::InvalidInstructions(
+                        "Amount greater than max amount",
+                    ));
+                }
+            }
+
+            let fixed_instructions = instructions
+                .set_amount(
+                    amount::Amount::from_sats(amount.to_sat()).unwrap(),
+                    &resolver,
+                )
+                .await
+                .map_err(|s| ParseError::InvalidInstructions(s))?;
+
+            process_fixed_instructions(amount, &fixed_instructions)
+        }
+
+        PaymentInstructions::FixedAmount(instructions) => {
+            process_fixed_instructions(amount, &instructions)
+        }
+    }
+}
+
+// pub async fn resolve_dns_recipient_with_resolver() -> Result<Payment, ParseError>>;
diff --git a/src/lib.rs b/src/lib.rs
index bcdf894..8a5eb6e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -35,6 +35,9 @@ pub use selection::*;
 pub use selector::*;
 pub use signer::*;
 
+#[cfg(feature = "bip353")]
+pub mod bip353_payment_instructions;
+
 #[cfg(feature = "std")]
 pub(crate) mod collections {
     #![allow(unused)]