From acad65477065c5fad94feefabefb1fb6988d796c Mon Sep 17 00:00:00 2001
From: Austin Foxley <afoxley@google.com>
Date: Wed, 27 Nov 2024 06:38:31 +0000
Subject: [PATCH] pw_bluetooth_proxy: Fix up checks in RfcommChannel
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Cleanups in logs, fix check conditions brought up in review.

Change-Id: I7c590191969f97320b977aa288d8e9af741de185
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/250995
Pigweed-Auto-Submit: Austin Foxley <afoxley@google.com>
Reviewed-by: David Rees <drees@google.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Docs-Not-Needed: Ben Lawson <benlawson@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
---
 .../public/pw_bluetooth_proxy/rfcomm_channel.h     |  2 +-
 pw_bluetooth_proxy/rfcomm_channel.cc               | 14 ++++++++------
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/pw_bluetooth_proxy/public/pw_bluetooth_proxy/rfcomm_channel.h b/pw_bluetooth_proxy/public/pw_bluetooth_proxy/rfcomm_channel.h
index 548e18dbc..e87242aee 100644
--- a/pw_bluetooth_proxy/public/pw_bluetooth_proxy/rfcomm_channel.h
+++ b/pw_bluetooth_proxy/public/pw_bluetooth_proxy/rfcomm_channel.h
@@ -108,7 +108,7 @@ class RfcommChannel final : public L2capWriteChannel, public L2capReadChannel {
   Config tx_config() const { return tx_config_; }
 
  private:
-  static constexpr uint8_t kMinRxCredits = 1;
+  static constexpr uint8_t kMinRxCredits = 2;
 
   RfcommChannel(L2capChannelManager& l2cap_channel_manager,
                 uint16_t connection_handle,
diff --git a/pw_bluetooth_proxy/rfcomm_channel.cc b/pw_bluetooth_proxy/rfcomm_channel.cc
index 84fd28beb..22f17e114 100644
--- a/pw_bluetooth_proxy/rfcomm_channel.cc
+++ b/pw_bluetooth_proxy/rfcomm_channel.cc
@@ -62,6 +62,7 @@ pw::Status RfcommChannel::Write(pw::span<const uint8_t> payload) {
                             length_extended_size + kCreditsFieldSize +
                             payload.size();
 
+  // TODO: https://pwbug.dev/365179076 - Support fragmentation.
   pw::Result<H4PacketWithH4> h4_result = PopulateTxL2capPacket(frame_size);
   if (!h4_result.ok()) {
     return h4_result.status();
@@ -112,6 +113,7 @@ pw::Status RfcommChannel::Write(pw::span<const uint8_t> payload) {
   if (rfcomm.information().SizeInBytes() < payload.size()) {
     return Status::ResourceExhausted();
   }
+  PW_CHECK(rfcomm.information().SizeInBytes() == payload.size());
   std::memcpy(rfcomm.information().BackingStorage().data(),
               payload.data(),
               payload.size());
@@ -148,7 +150,8 @@ Result<RfcommChannel> RfcommChannel::Create(
     uint8_t channel_number,
     pw::Function<void(pw::span<uint8_t> payload)>&& receive_fn) {
   if (!L2capWriteChannel::AreValidParameters(connection_handle,
-                                             tx_config.cid)) {
+                                             tx_config.cid) ||
+      !L2capReadChannel::AreValidParameters(connection_handle, rx_config.cid)) {
     return Status::InvalidArgument();
   }
 
@@ -170,10 +173,9 @@ bool RfcommChannel::HandlePduFromController(pw::span<uint8_t> l2cap_pdu) {
       MakeEmbossView<emboss::BFrameView>(l2cap_pdu);
   if (!bframe_view.ok()) {
     PW_LOG_ERROR(
-        "(CID 0x%X) Buffer is too small for L2CAP B-frame. So stopping channel "
-        "& reporting it needs to be closed.",
+        "(CID 0x%X) Buffer is too small for L2CAP B-frame, passing on to host.",
         local_cid());
-    return true;
+    return false;
   }
 
   Result<emboss::RfcommFrameView> rfcomm_view =
@@ -232,7 +234,7 @@ bool RfcommChannel::HandlePduFromController(pw::span<uint8_t> l2cap_pdu) {
     } else {
       --rx_credits_;
     }
-    rx_needs_refill = rx_credits_ <= kMinRxCredits;
+    rx_needs_refill = rx_credits_ < kMinRxCredits;
   }
 
   if (rx_needs_refill) {
@@ -276,7 +278,7 @@ RfcommChannel::RfcommChannel(
 void RfcommChannel::OnFragmentedPduReceived() {
   PW_LOG_ERROR(
       "(CID 0x%X) Fragmented L2CAP frame received (which is not yet "
-      "supported). Stopping channel.",
+      "supported).",
       local_cid());
 }