From a308515aea80ca89d23cc7f3f2a00208be3d6e45 Mon Sep 17 00:00:00 2001
From: Alex Janka <alex@alexjanka.com>
Date: Thu, 22 Feb 2024 10:58:49 +1100
Subject: [PATCH] error out on error in tlv

---
 homekit-controller/src/lib.rs      | 32 +++++++++++++++++++++---------
 homekit-controller/src/tlv8/mod.rs |  3 +--
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/homekit-controller/src/lib.rs b/homekit-controller/src/lib.rs
index 976aa36..5a2badd 100644
--- a/homekit-controller/src/lib.rs
+++ b/homekit-controller/src/lib.rs
@@ -1,10 +1,12 @@
-use chacha20poly1305::{aead::generic_array::GenericArray, AeadInPlace, ChaCha20Poly1305, KeyInit};
+use chacha20poly1305::{
+    aead::generic_array::GenericArray, AeadInPlace, ChaCha20Poly1305, KeyInit, Nonce,
+};
 use ed25519_dalek::{Signer, Verifier};
 use hkdf::Hkdf;
 use sha2::Sha512;
 use std::{collections::HashMap, path::PathBuf};
 use thiserror::Error;
-use tlv8::{HomekitState, TlvEncode, TlvType};
+use tlv8::{HomekitState, TlvEncode, TlvError, TlvType};
 use x25519_dalek::{EphemeralSecret, PublicKey};
 
 use pairing_data::DevicePairingData;
@@ -164,13 +166,9 @@ impl DevicePairingData {
         .encode();
 
         // 10. Encrypt sub-TLV: encryptedData, authTag = ChaCha20-Poly1305(SessionKey, Nonce=”PV-Msg03”, AAD=<none>, Msg=<Sub-TLV>)
-        let nonce: [u8; 12] = [0; 4]
-            .iter()
-            .chain(b"PV-Msg03")
-            .copied()
-            .collect::<Vec<_>>()
-            .try_into()?;
-        chacha.encrypt_in_place(GenericArray::from_slice(&nonce), &[], &mut encrypted_tlv)?;
+        let mut nonce = [0; 12];
+        nonce[4..].copy_from_slice(b"PV-Msg03");
+        chacha.encrypt_in_place(Nonce::from_slice(&nonce), &[], &mut encrypted_tlv)?;
 
         // 11/12 Construct TLV response and send to accessory
         let step3_response = decode(
@@ -196,6 +194,14 @@ impl DevicePairingData {
             return Err(HomekitError::StateMismatch);
         }
 
+        if let Some(error) = step3_response.get(&TlvType::Error.into()) {
+            if let Some(e) = error.first().and_then(|v| TlvError::try_from(*v).ok()) {
+                return Err(e.into());
+            }
+            log::error!("got tlv error from device but couldn't parse it from the data!");
+            return Err(HomekitError::TlvNotFound);
+        }
+
         // 5.7.4 M4: Accessory -> iOS Device – ‘Verify Finish Responseʼ
         // When the accessory receives <M3>, it must perform the following steps:
         //
@@ -299,6 +305,14 @@ pub enum HomekitError {
     SomethingElse(String),
     #[error("addr parse")]
     AddrParse(#[from] std::net::AddrParseError),
+    #[error("tlv error from device")]
+    TlvDeviceError(TlvError),
+}
+
+impl From<TlvError> for HomekitError {
+    fn from(value: TlvError) -> Self {
+        Self::TlvDeviceError(value)
+    }
 }
 
 impl From<String> for HomekitError {
diff --git a/homekit-controller/src/tlv8/mod.rs b/homekit-controller/src/tlv8/mod.rs
index bc04c69..76cfff4 100644
--- a/homekit-controller/src/tlv8/mod.rs
+++ b/homekit-controller/src/tlv8/mod.rs
@@ -1,8 +1,7 @@
-use self::data_types::TlvError;
 use std::collections::HashMap;
 use thiserror::Error;
 
-pub use data_types::{HomekitState, TlvType};
+pub use data_types::{HomekitState, TlvError, TlvType};
 
 mod data_types;