From 82ab7f7d2c710aaed04de8a0c38e4160ed019bf8 Mon Sep 17 00:00:00 2001
From: oxalica <oxalicc@pm.me>
Date: Thu, 19 Sep 2024 02:34:21 -0400
Subject: [PATCH] refactor(types): move `UserIdentityDesc` verification into
 types crate

---
 blah-types/src/identity.rs | 60 ++++++++++++++++++++++++++++++++++++++
 blahd/src/register.rs      | 59 +++++--------------------------------
 2 files changed, 67 insertions(+), 52 deletions(-)

diff --git a/blah-types/src/identity.rs b/blah-types/src/identity.rs
index cb0a1fc..fea3aaf 100644
--- a/blah-types/src/identity.rs
+++ b/blah-types/src/identity.rs
@@ -2,6 +2,7 @@ use core::fmt;
 use std::ops;
 use std::str::FromStr;
 
+use ed25519_dalek::SignatureError;
 use serde::{Deserialize, Serialize};
 use thiserror::Error;
 use url::{Host, Position, Url};
@@ -20,8 +21,67 @@ pub struct UserIdentityDesc {
     pub profile: Signed<UserProfile>,
 }
 
+#[derive(Debug, Error)]
+#[error(transparent)]
+pub struct VerfiyError(#[from] VerifyErrorImpl);
+
+#[derive(Debug, Error)]
+enum VerifyErrorImpl {
+    #[error("profile id_key mismatch")]
+    ProfileIdKeyMismatch,
+    #[error("act_key[{0}] not signed by id_key")]
+    ActKeySigner(usize),
+    #[error("invalid act_key[{0}] signature: {1}")]
+    ActKeySignature(usize, SignatureError),
+    #[error("profile is not signed by any valid act_key")]
+    ProfileSigner,
+    #[error("invalid profile signature: {0}")]
+    ProfileSignature(SignatureError),
+    #[error("id_url is not in the valid list")]
+    MissingIdUrl,
+}
+
 impl UserIdentityDesc {
     pub const WELL_KNOWN_PATH: &str = "/.well-known/blah/identity.json";
+
+    /// Validate signatures of the identity description at given time.
+    pub fn verify(&self, id_url: Option<&IdUrl>, now_timestamp: u64) -> Result<(), VerfiyError> {
+        if self.id_key != self.profile.signee.user.id_key {
+            return Err(VerifyErrorImpl::ProfileIdKeyMismatch.into());
+        }
+
+        let profile_signing_key = &self.profile.signee.user.act_key;
+        let mut profile_signed = false;
+
+        for (i, signed_kdesc) in self.act_keys.iter().enumerate() {
+            let kdesc = &signed_kdesc.signee.payload;
+            // act_key itself is signed by id_key, so both are id_key here.
+            if signed_kdesc.signee.user.id_key != self.id_key
+                || signed_kdesc.signee.user.act_key != self.id_key
+            {
+                return Err(VerifyErrorImpl::ActKeySigner(i).into());
+            }
+            signed_kdesc
+                .verify()
+                .map_err(|err| VerifyErrorImpl::ActKeySignature(i, err))?;
+            if now_timestamp < kdesc.expire_time && *profile_signing_key == kdesc.act_key {
+                profile_signed = true;
+            }
+        }
+
+        if !profile_signed {
+            return Err(VerifyErrorImpl::ProfileSigner.into());
+        }
+        self.profile
+            .verify()
+            .map_err(VerifyErrorImpl::ProfileSignature)?;
+        if let Some(id_url) = id_url {
+            if !self.profile.signee.payload.id_urls.contains(id_url) {
+                return Err(VerifyErrorImpl::MissingIdUrl.into());
+            }
+        }
+        Ok(())
+    }
 }
 
 // TODO: JWS or alike?
diff --git a/blahd/src/register.rs b/blahd/src/register.rs
index 05dfd44..24c7aa3 100644
--- a/blahd/src/register.rs
+++ b/blahd/src/register.rs
@@ -1,12 +1,10 @@
 use std::num::NonZero;
 use std::time::{Duration, Instant};
 
-use anyhow::{anyhow, ensure, Context};
+use anyhow::{anyhow, ensure};
 use axum::http::{HeaderMap, HeaderName, StatusCode};
 use blah_types::identity::{IdUrl, UserIdentityDesc};
-use blah_types::{
-    get_timestamp, PubKey, Signed, UserRegisterPayload, X_BLAH_DIFFICULTY, X_BLAH_NONCE,
-};
+use blah_types::{get_timestamp, Signed, UserRegisterPayload, X_BLAH_DIFFICULTY, X_BLAH_NONCE};
 use http_body_util::BodyExt;
 use parking_lot::Mutex;
 use rand::rngs::OsRng;
@@ -246,7 +244,11 @@ pub async fn user_register(
         }
     };
 
-    if let Err(err) = validate_id_desc(&reg.id_url, &reg.id_key, &id_desc, fetch_time) {
+    if let Err(err) = (|| {
+        ensure!(reg.id_key == id_desc.id_key, "id_key mismatch");
+        id_desc.verify(Some(&reg.id_url), fetch_time)?;
+        Ok(())
+    })() {
         return Err(error_response!(
             StatusCode::UNAUTHORIZED,
             "invalid_id_description",
@@ -314,53 +316,6 @@ pub async fn user_register(
     Ok(StatusCode::NO_CONTENT)
 }
 
-fn validate_id_desc(
-    id_url: &IdUrl,
-    id_key: &PubKey,
-    id_desc: &UserIdentityDesc,
-    now: u64,
-) -> anyhow::Result<()> {
-    ensure!(*id_key == id_desc.id_key, "id_key mismatch");
-
-    ensure!(
-        *id_key == id_desc.profile.signee.user.id_key,
-        "profile id_key mismatch",
-    );
-    let profile_signing_key = &id_desc.profile.signee.user.act_key;
-    let mut profile_signed = false;
-
-    for (i, signed_kdesc) in id_desc.act_keys.iter().enumerate() {
-        let kdesc = &signed_kdesc.signee.payload;
-        (|| {
-            // act_key itself is signed by id_key, so both are id_key here.
-            ensure!(
-                signed_kdesc.signee.user.id_key == *id_key
-                    && signed_kdesc.signee.user.act_key == *id_key,
-                "not signed by id_key",
-            );
-            signed_kdesc
-                .verify()
-                .context("signature verification failed")?;
-            if now < kdesc.expire_time && *profile_signing_key == kdesc.act_key {
-                profile_signed = true;
-            }
-            Ok(())
-        })()
-        .map_err(|err| anyhow!("invalid act_key[{}] {}: {}", i, kdesc.act_key, err))?;
-    }
-
-    ensure!(profile_signed, "profile is not signed by valid act_keys");
-    id_desc
-        .profile
-        .verify()
-        .context("profile signature verification failed")?;
-    ensure!(
-        id_desc.profile.signee.payload.id_urls == std::slice::from_ref(id_url),
-        "id_url list must consists of a single matching id_url",
-    );
-    Ok(())
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;