Rename datapath callback types for transport generalization by guhetier · Pull Request #6070 · microsoft/msquic

guhetier · 2026-06-06T00:32:59Z

Description

Rename datapath callback types to make them more generic based on datagram or connection-oriented transport, since MsQuic is going to support other transports than UDP/TCP.

Testing

CI

Documentation

N/A, the types are internal

codecov · 2026-06-06T01:30:25Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.66%. Comparing base (6525fb3) to head (cb073b4).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6070      +/-   ##
==========================================
- Coverage   85.93%   85.66%   -0.28%     
==========================================
  Files          60       60              
  Lines       18798    18798              
==========================================
- Hits        16155    16103      -52     
- Misses       2643     2695      +52

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The binding trace events refer to the socket object generically, not specifically a UDP socket. Rename for clarity since bindings can now use different transport types (UDP, TCP, RDMA). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Rename datapath callback type names for consistency: - CXPLAT_UDP_DATAPATH_CALLBACKS -> CXPLAT_DATAPATH_DGRAM_CALLBACKS - CXPLAT_TCP_DATAPATH_CALLBACKS -> CXPLAT_DATAPATH_CONN_CALLBACKS Variable/field names (UdpCallbacks, TcpCallbacks, UdpHandlers, TcpHandlers) are kept as-is since they are used in transport-specific contexts where the protocol is known. The type naming reflects the transport model (datagram vs connection- oriented) rather than specific protocols (UDP/TCP), since RDMA RC is connection-oriented but not a stream. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR updates MsQuic’s internal datapath callback type names to be transport-generic (datagram vs. connection-oriented), aligning terminology with planned support for transports beyond UDP/TCP. It also updates binding trace strings to use “Socket” terminology and includes the corresponding CLOG/ETW artifacts.

Changes:

Renamed CXPLAT_{UDP,TCP}_DATAPATH_CALLBACKS to CXPLAT_DATAPATH_{DGRAM,CONN}_CALLBACKS and updated call sites across tools, tests, perf code, and platform implementations.
Updated binding trace strings from Udp=... to Socket=... in code and ETW/CLOG metadata, including regenerated Linux CLOG headers and clog.sidecar.
Updated datapath initialization signatures and handler storage types to use the new callback struct names.

Reviewed changes

Copilot reviewed 20 out of 22 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/tools/recvfuzz/recvfuzz.cpp	Switch recvfuzz datapath callback struct to `CXPLAT_DATAPATH_DGRAM_CALLBACKS`.
src/tools/lb/loadbalancer.cpp	Update load balancer tool to use `CXPLAT_DATAPATH_DGRAM_CALLBACKS`.
src/tools/attack/attack.cpp	Update attack tool datapath callbacks to new datagram callback type.
src/test/lib/QuicDrill.cpp	Update QuicDrill datapath callback struct to new datagram callback type.
src/platform/unittest/DataPathTest.cpp	Update unit tests to use new datagram/connection callback struct types and updated init wrapper signature.
src/platform/platform_internal.h	Update internal datapath common handler storage and `DataPathInitialize` prototype to new callback types.
src/platform/datapath_xplat.c	Update `CxPlatDataPathInitialize` signature to new callback types.
src/platform/datapath_winuser.c	Update `DataPathInitialize` signature to new callback types (winuser).
src/platform/datapath_winkernel.c	Update `DataPathInitialize` signature to new callback types (winkernel).
src/platform/datapath_kqueue.c	Update UDP handler storage and init signature to new callback types (kqueue).
src/platform/datapath_iouring.c	Update `DataPathInitialize` signature to new callback types (io_uring).
src/platform/datapath_epoll.c	Update `DataPathInitialize` signature to new callback types (epoll).
src/perf/lib/Tcp.h	Update perf TCP engine callback declaration to new connection callback type.
src/perf/lib/Tcp.cpp	Update perf TCP engine callback definition to new connection callback type.
src/perf/lib/SecNetPerfMain.cpp	Update secnetperf’s datapath callback struct to new datagram callback type.
src/manifest/MsQuicEtw.man	Update ETW string resources to use “Socket” instead of “Udp” for binding events.
src/manifest/clog.sidecar	Update CLOG trace strings/hashes for binding events to “Socket”.
src/inc/quic_datapath.h	Rename the callback struct typedefs and datapath init prototype to the new datagram/connection callback types.
src/generated/linux/binding.c.clog.h.lttng.h	Regenerated Linux LTTng CLOG header reflecting updated binding trace strings.
src/generated/linux/binding.c.clog.h	Regenerated Linux CLOG header reflecting updated binding trace strings.
src/core/library.c	Update library datapath initialization to use new datagram callback struct type.
src/core/binding.c	Update binding trace strings from “Udp” to “Socket” for created/rundown events.

 //
 // UDP Callback function pointers used by the datapath.
 //
-typedef struct CXPLAT_UDP_DATAPATH_CALLBACKS {
+typedef struct CXPLAT_DATAPATH_DGRAM_CALLBACKS {


 //
 // TCP Callback function pointers used by the datapath.
 //
-typedef struct CXPLAT_TCP_DATAPATH_CALLBACKS {
+typedef struct CXPLAT_DATAPATH_CONN_CALLBACKS {


    //
    // The UDP callback function pointers.
    //
-    CXPLAT_UDP_DATAPATH_CALLBACKS UdpHandlers;
+    CXPLAT_DATAPATH_DGRAM_CALLBACKS UdpHandlers;


    //
    // The TCP callback function pointers.
    //
-    CXPLAT_TCP_DATAPATH_CALLBACKS TcpHandlers;
+    CXPLAT_DATAPATH_CONN_CALLBACKS TcpHandlers;


mtfriesen · 2026-06-10T18:27:02Z

    //
    // UDP handlers.
    //
-    CXPLAT_UDP_DATAPATH_CALLBACKS UdpHandlers;
+    CXPLAT_DATAPATH_DGRAM_CALLBACKS UdpHandlers;


Generally agree it would be best to do a comprehensive refactor.

I'll fix the comments, in most places.
In that one specifically, "UDP handlers" is accurate, because we are in a specific datapath that deals with UDP (while from the core layer point of view, it shouldn't matter)

mtfriesen · 2026-06-10T18:25:38Z

-    _In_opt_ const CXPLAT_UDP_DATAPATH_CALLBACKS* UdpCallbacks,
-    _In_opt_ const CXPLAT_TCP_DATAPATH_CALLBACKS* TcpCallbacks,
+    _In_opt_ const CXPLAT_DATAPATH_DGRAM_CALLBACKS* UdpCallbacks,
+    _In_opt_ const CXPLAT_DATAPATH_CONN_CALLBACKS* TcpCallbacks,


From a naming perspective, I'd follow the BSD socket types, since their abstraction is about as good as any:

DGRAM_CALLBACKS for a datapath built upon SOCK_DGRAM semantics
STREAM_CALLBACKS for a datapath built upon SOCK_STREAM semantics instead of CONN_CALLBACKS

This is imperfect, for sure, but should be most intuitive as long as our set of datapath models roughly align with BSD socket semantics.

I considered STREAM, but what hold me is that for RDMA, for instance, we have a connection-oriented, reliable, datagram-oriented protocol, but not a stream.

If you think STREAM is more intuitive and is worth the slight over-use, I'm ok going with it.

mtfriesen · 2026-06-10T18:26:15Z

    _In_ uint32_t ClientRecvContextLength,
-    _In_opt_ const CXPLAT_UDP_DATAPATH_CALLBACKS* UdpCallbacks,
-    _In_opt_ const CXPLAT_TCP_DATAPATH_CALLBACKS* TcpCallbacks,
+    _In_opt_ const CXPLAT_DATAPATH_DGRAM_CALLBACKS* UdpCallbacks,


If we're claiming this is more abstracted, should we also rename the variables from Udp/Tcp? Or is that out of scope for now / forever?

It makes sense to do it here.
I first did a big research replace and reverted it because for most instances, UdpCallbacks is actually specifically about UDP, but this definition is generic.

mtfriesen · 2026-06-10T18:28:49Z

N/A, the types are internal

I would like to improve the documentation around the internal data path layer - we sure have had a lot of design questions lately. If there's a reasonable spot to start a skeleton, let's do that so future PRs have one less reason to say "no" to documentation.

guhetier · 2026-06-11T19:34:53Z

N/A, the types are internal

I would like to improve the documentation around the internal data path layer - we sure have had a lot of design questions lately. If there's a reasonable spot to start a skeleton, let's do that so future PRs have one less reason to say "no" to documentation.

I'll add a skeleton doc we can populate progressively, it is as good of a time as any. Note this isn't about datapath refactoring (yet), but prep work toward supporting connection-oriented transports in the core layer.

guhetier force-pushed the guhetier/rename_datapath_types branch from 37280b8 to 73f7864 Compare June 6, 2026 00:40

guhetier force-pushed the guhetier/rename_datapath_types branch from 73f7864 to 2939c25 Compare June 9, 2026 00:26

guhetier and others added 2 commits June 8, 2026 17:39

guhetier force-pushed the guhetier/rename_datapath_types branch from 2939c25 to cb073b4 Compare June 9, 2026 00:52

guhetier changed the title ~~Rename UDP_CONFIG and callback types for transport generalization~~ Rename datapath callback types for transport generalization Jun 9, 2026

guhetier marked this pull request as ready for review June 9, 2026 15:52

guhetier requested a review from a team as a code owner June 9, 2026 15:52

mtfriesen requested a review from Copilot June 10, 2026 17:48

Copilot started reviewing on behalf of mtfriesen June 10, 2026 17:48 View session

Copilot AI reviewed Jun 10, 2026

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mtfriesen reviewed Jun 10, 2026

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Rename datapath callback types for transport generalization#6070

Rename datapath callback types for transport generalization#6070
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