add fn to fetch invoice

Cargo.toml

@@ -22,7 +22,7 @@ panic = "abort"
 [dependencies]
 serde = { version = "1.0.0", features = ["derive"] }
 serde_json = "1.0.0"
-ureq = { version = "2.9.7", features = ["json", "native-tls"] }
+ureq = { version = "2.5.0", features = ["json", "native-tls", "socks"] }
 bip39 = "2.0.0"
 electrum-client = "0.19.0"
 bitcoin = {version = "0.31.2", features = ["rand", "base64", "rand-std"]}
@@ -34,6 +34,8 @@ log = "^0.4"
 env_logger = "0.7"
 native-tls = "0.2.11"
 hex = "0.4"
+lnurl-rs = "0.8.0"
+reqwest = { version = "0.12.7", features = ["json"] }
 
 [patch.crates-io]
 secp256k1-zkp = {git = "https://github.com/BlockstreamResearch/rust-secp256k1-zkp.git", rev = "60e631c24588a0c9e271badd61959294848c665d"}

src/util/lnurl.rs

@@ -0,0 +1,21 @@
+use lightning_invoice::Bolt11Invoice;
+use lnurl::{
+    lnurl::LnUrl,
+    Builder,
+    LnUrlResponse
+};
+use std::error::Error;
+use std::str::FromStr;
+async fn fetch_invoice(lnurl_string: &str, amount_msats: u64) -> Result<String, dyn Error> {
+    let lnurl = LnUrl::from_str(lnurl_string)?;
+    let async_client = Builder::default().build_async()?;
+    let res = async_client.make_request(&lnurl_string).await?;
+    if let LnUrlResponse::LnUrlPayResponse(pay) = res {
+        let pay_result = async_client.get_invoice(&pay, amount_msats, None, None).await?;
+        let invoice = Bolt11Invoice::from_str(&pay_result.invoice())?;
+        if invoice.amount_milli_satoshis() != Some(amount_msats) {
+            return Err("Invoice amount doesn't match requested amount".into());
+        }
+        Ok(pay_result.invoice().to_string())
+    } else { panic!("Wrong response type"); }
+}

src/util/mod.rs

@@ -9,6 +9,7 @@ use crate::{error::Error, network::electrum::ElectrumConfig};
 
 pub mod ec;
 pub mod secrets;
+mod lnurl;
 
 /// Setup function that will only run once, even if called multiple times.