Impl traits for session persistence

payjoin/Cargo.toml

@@ -18,7 +18,7 @@ exclude = ["tests"]
 send = []
 receive = ["rand"]
 base64 = ["bitcoin/base64"]
-v2 = ["bitcoin/rand-std", "chacha20poly1305", "ohttp", "bhttp"]
+v2 = ["bitcoin/rand-std", "chacha20poly1305", "ohttp", "bhttp", "serde"]
 
 [dependencies]
 bitcoin = { version = "0.30.0", features = ["base64"] }
@@ -28,6 +28,7 @@ log = { version = "0.4.14"}
 ohttp = { version = "0.4.0", optional = true }
 bhttp = { version = "0.4.0", optional = true }
 rand = { version = "0.8.4", optional = true }
+serde = { version = "1.0.186", default-features = false, optional = true }
 url = "2.2.2"
 
 [dev-dependencies]

payjoin/src/receive/v2.rs

@@ -2,6 +2,8 @@ use std::collections::HashMap;
 
 use bitcoin::psbt::Psbt;
 use bitcoin::{base64, Amount, FeeRate, OutPoint, Script, TxOut};
+use serde::ser::SerializeStruct;
+use serde::{Deserialize, Serialize, Serializer};
 
 use super::{Error, InternalRequestError, RequestError, SelectionError};
 use crate::psbt::PsbtExt;
@@ -107,14 +109,146 @@ fn subdirectory(pubkey: &bitcoin::secp256k1::PublicKey) -> String {
     pubkey_base64
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct Enrolled {
     relay_url: url::Url,
     ohttp_config: Vec<u8>,
     ohttp_proxy: url::Url,
     s: bitcoin::secp256k1::KeyPair,
 }
 
+impl Serialize for Enrolled {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut state = serializer.serialize_struct("Enrolled", 4)?;
+        state.serialize_field("relay_url", &self.relay_url.to_string())?;
+        state.serialize_field("ohttp_config", &self.ohttp_config)?;
+        state.serialize_field("ohttp_proxy", &self.ohttp_proxy.to_string())?;
+        state.serialize_field("s", &self.s.secret_key().secret_bytes())?;
+
+        state.end()
+    }
+}
+
+use std::fmt;
+use std::str::FromStr;
+
+use serde::de::{self, Deserializer, MapAccess, SeqAccess, Visitor};
+
+impl<'de> Deserialize<'de> for Enrolled {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        enum Field {
+            RelayUrl,
+            OhttpConfig,
+            OhttpProxy,
+            S,
+        }
+
+        impl<'de> Deserialize<'de> for Field {
+            fn deserialize<D>(deserializer: D) -> Result<Field, D::Error>
+            where
+                D: Deserializer<'de>,
+            {
+                struct FieldVisitor;
+
+                impl<'de> Visitor<'de> for FieldVisitor {
+                    type Value = Field;
+
+                    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                        formatter.write_str("`relay_url`, `ohttp_config`, `ohttp_proxy`, or `s`")
+                    }
+
+                    fn visit_str<E>(self, value: &str) -> Result<Field, E>
+                    where
+                        E: de::Error,
+                    {
+                        match value {
+                            "relay_url" => Ok(Field::RelayUrl),
+                            "ohttp_config" => Ok(Field::OhttpConfig),
+                            "ohttp_proxy" => Ok(Field::OhttpProxy),
+                            "s" => Ok(Field::S),
+                            _ => Err(de::Error::unknown_field(value, FIELDS)),
+                        }
+                    }
+                }
+
+                deserializer.deserialize_identifier(FieldVisitor)
+            }
+        }
+
+        struct EnrolledVisitor;
+
+        impl<'de> Visitor<'de> for EnrolledVisitor {
+            type Value = Enrolled;
+
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("struct Enrolled")
+            }
+
+            fn visit_map<V>(self, mut map: V) -> Result<Enrolled, V::Error>
+            where
+                V: MapAccess<'de>,
+            {
+                let mut relay_url = None;
+                let mut ohttp_config = None;
+                let mut ohttp_proxy = None;
+                let mut s = None;
+                while let Some(key) = map.next_key()? {
+                    match key {
+                        Field::RelayUrl => {
+                            if relay_url.is_some() {
+                                return Err(de::Error::duplicate_field("relay_url"));
+                            }
+                            let url_str: String = map.next_value()?;
+                            relay_url = Some(url::Url::parse(&url_str).map_err(de::Error::custom)?);
+                        }
+                        Field::OhttpConfig => {
+                            if ohttp_config.is_some() {
+                                return Err(de::Error::duplicate_field("ohttp_config"));
+                            }
+                            ohttp_config = Some(map.next_value()?);
+                        }
+                        Field::OhttpProxy => {
+                            if ohttp_proxy.is_some() {
+                                return Err(de::Error::duplicate_field("ohttp_proxy"));
+                            }
+                            let proxy_str: String = map.next_value()?;
+                            ohttp_proxy =
+                                Some(url::Url::parse(&proxy_str).map_err(de::Error::custom)?);
+                        }
+                        Field::S => {
+                            if s.is_some() {
+                                return Err(de::Error::duplicate_field("s"));
+                            }
+                            let s_bytes: Vec<u8> = map.next_value()?;
+                            let secp = bitcoin::secp256k1::Secp256k1::new();
+                            s = Some(
+                                bitcoin::secp256k1::KeyPair::from_seckey_slice(&secp, &s_bytes)
+                                    .map_err(de::Error::custom)?,
+                            );
+                        }
+                    }
+                }
+                let relay_url = relay_url.ok_or_else(|| de::Error::missing_field("relay_url"))?;
+                let ohttp_config =
+                    ohttp_config.ok_or_else(|| de::Error::missing_field("ohttp_config"))?;
+                let ohttp_proxy =
+                    ohttp_proxy.ok_or_else(|| de::Error::missing_field("ohttp_proxy"))?;
+                let s = s.ok_or_else(|| de::Error::missing_field("s"))?;
+                Ok(Enrolled { relay_url, ohttp_config, ohttp_proxy, s })
+            }
+        }
+
+        const FIELDS: &'static [&'static str] = &["relay_url", "ohttp_config", "ohttp_proxy", "s"];
+        deserializer.deserialize_struct("Enrolled", FIELDS, EnrolledVisitor)
+    }
+}
+
 impl Enrolled {
     pub fn extract_req(&self) -> Result<(Request, ohttp::ClientResponse), Error> {
         let (body, ohttp_ctx) = self.fallback_req_body()?;
@@ -174,6 +308,8 @@ impl Enrolled {
         crate::v2::ohttp_encapsulate(&self.ohttp_config, "GET", &self.fallback_target(), None)
     }
 
+    pub fn pubkey(&self) -> [u8; 33] { self.s.public_key().serialize() }
+
     pub fn fallback_target(&self) -> String {
         let pubkey = &self.s.public_key().serialize();
         let b64_config = base64::Config::new(base64::CharacterSet::UrlSafe, false);