From 40536b13da4d4b720bddb590f9158f110a9ef6fa Mon Sep 17 00:00:00 2001
From: Jade Ellis <jade@ellis.link>
Date: Wed, 11 Feb 2026 18:21:19 +0000
Subject: [PATCH] feat: Add experimental http3 support

Only enabled in Docker builds for now, due to build config required. Not
sure if more work is needed for 0RTT.
---
 Cargo.lock                 | 37 +++++++++++++++++++++++++++++++++++++
 docker/Dockerfile          | 10 ++++++++++
 docs/deploying/generic.mdx |  2 ++
 src/api/Cargo.toml         |  4 ++++
 src/core/Cargo.toml        |  3 +++
 src/main/Cargo.toml        |  5 +++++
 src/service/Cargo.toml     |  3 +++
 7 files changed, 64 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index 54ea9964..639a2507 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1857,6 +1857,12 @@ dependencies = [
  "zune-inflate",
 ]
 
+[[package]]
+name = "fastrand"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
+
 [[package]]
 name = "fax"
 version = "0.2.6"
@@ -2157,6 +2163,34 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "h3"
+version = "0.0.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10872b55cfb02a821b69dc7cf8dc6a71d6af25eb9a79662bec4a9d016056b3be"
+dependencies = [
+ "bytes",
+ "fastrand",
+ "futures-util",
+ "http",
+ "pin-project-lite",
+ "tokio",
+]
+
+[[package]]
+name = "h3-quinn"
+version = "0.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b2e732c8d91a74731663ac8479ab505042fbf547b9a207213ab7fbcbfc4f8b4"
+dependencies = [
+ "bytes",
+ "futures",
+ "h3",
+ "quinn",
+ "tokio",
+ "tokio-util",
+]
+
 [[package]]
 name = "half"
 version = "2.7.1"
@@ -3919,6 +3953,7 @@ checksum = "b9e20a958963c291dc322d98411f541009df2ced7b5a4f2bd52337638cfccf20"
 dependencies = [
  "bytes",
  "cfg_aliases",
+ "futures-io",
  "pin-project-lite",
  "quinn-proto",
  "quinn-udp",
@@ -4171,6 +4206,8 @@ dependencies = [
  "futures-core",
  "futures-util",
  "h2",
+ "h3",
+ "h3-quinn",
  "hickory-resolver",
  "http",
  "http-body",
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 7239a08e..76b8bcb1 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -162,6 +162,7 @@ ENV CONDUWUIT_VERSION_EXTRA=$CONDUWUIT_VERSION_EXTRA
 ENV CONTINUWUITY_VERSION_EXTRA=$CONTINUWUITY_VERSION_EXTRA
 
 ARG RUST_PROFILE=release
+ARG CARGO_FEATURES="default,http3"
 
 # Build the binary
 RUN --mount=type=cache,target=/usr/local/cargo/registry \
@@ -171,11 +172,20 @@ RUN --mount=type=cache,target=/usr/local/cargo/registry \
     set -o allexport
     set -o xtrace
     . /etc/environment
+
+    # Check if http3 feature is enabled and set appropriate RUSTFLAGS
+    if echo "${CARGO_FEATURES}" | grep -q "http3"; then
+        export RUSTFLAGS="${RUSTFLAGS} --cfg reqwest_unstable"
+    else
+        export RUSTFLAGS="${RUSTFLAGS}"
+    fi
+
     TARGET_DIR=($(cargo metadata --no-deps --format-version 1 | \
             jq -r ".target_directory"))
     mkdir /out/sbin
     PACKAGE=conduwuit
     xx-cargo build --locked --profile ${RUST_PROFILE} \
+        --no-default-features --features ${CARGO_FEATURES} \
         -p $PACKAGE;
     BINARIES=($(cargo metadata --no-deps --format-version 1 | \
         jq -r ".packages[] | select(.name == \"$PACKAGE\") | .targets[] | select( .kind | map(. == \"bin\") | any ) | .name"))
diff --git a/docs/deploying/generic.mdx b/docs/deploying/generic.mdx
index 9a501298..416cc694 100644
--- a/docs/deploying/generic.mdx
+++ b/docs/deploying/generic.mdx
@@ -56,6 +56,8 @@ If wanting to build using standard Rust toolchains, make sure you install:
 
 You can build Continuwuity using `cargo build --release`.
 
+Continuwuity supports various optional features that can be enabled during compilation. Please see the Cargo.toml file for a comprehensive list, or ask in our rooms.
+
 ### Building with Nix
 
 If you prefer, you can use Nix (or [Lix](https://lix.systems)) to build Continuwuity. This provides improved reproducibility and makes it easy to set up a build environment and generate output. This approach also allows for easy cross-compilation.
diff --git a/src/api/Cargo.toml b/src/api/Cargo.toml
index 393ceecf..6f1779bc 100644
--- a/src/api/Cargo.toml
+++ b/src/api/Cargo.toml
@@ -28,6 +28,10 @@ gzip_compression = [
 	"conduwuit-service/gzip_compression",
 	"reqwest/gzip",
 ]
+http3 = [
+	"conduwuit-core/http3",
+	"conduwuit-service/http3",
+]
 io_uring = [
 	"conduwuit-service/io_uring",
 ]
diff --git a/src/core/Cargo.toml b/src/core/Cargo.toml
index 8139f2d3..4edaad03 100644
--- a/src/core/Cargo.toml
+++ b/src/core/Cargo.toml
@@ -24,6 +24,9 @@ conduwuit_mods = [
 gzip_compression = [
 	"reqwest/gzip",
 ]
+http3 = [
+	"reqwest/http3",
+]
 hardened_malloc = [
 	"dep:hardened_malloc-rs"
 ]
diff --git a/src/main/Cargo.toml b/src/main/Cargo.toml
index 7a4dd4d6..0a02384a 100644
--- a/src/main/Cargo.toml
+++ b/src/main/Cargo.toml
@@ -99,6 +99,11 @@ gzip_compression = [
 hardened_malloc = [
 	"conduwuit-core/hardened_malloc",
 ]
+http3 = [
+	"conduwuit-api/http3",
+	"conduwuit-core/http3",
+	"conduwuit-service/http3",
+]
 io_uring = [
 	"conduwuit-database/io_uring",
 ]
diff --git a/src/service/Cargo.toml b/src/service/Cargo.toml
index c89b39b4..8591496b 100644
--- a/src/service/Cargo.toml
+++ b/src/service/Cargo.toml
@@ -32,6 +32,9 @@ gzip_compression = [
 	"conduwuit-core/gzip_compression",
 	"reqwest/gzip",
 ]
+http3 = [
+	"conduwuit-core/http3",
+]
 io_uring = [
 	"conduwuit-database/io_uring",
 ]