Put ngtcp2 beside quinn in M5, as the design planned

ngtcp2 1.25.0 with OpenSSL 3.5's QUIC TLS (its ossl backend), fetched
and built into build/third by ngtcp2/build.sh; drain.c does in C what
the quinn harness does: one connection, one stream, "pure" and then the
messages each after its u32 length, counted by the service, packets in
GSO bursts. Its stream bytes are a function of their offset, so what
ngtcp2 keeps to send again points into a pattern that never changes.
run.py's drain_ngtcp2 measures both sides' CPU as drain_quic does.

Five rounds each, both sides' CPU a message: 61 B Pure 0.280, ngtcp2
0.270, quinn 0.310 us; 1 KiB 2.62, 3.54, 3.94; 16 KiB 40.2, 54.4, 60.2.

1 files changed, 16 insertions, 0 deletions

diff --git a/research/experiments/019-idle-links/ngtcp2/build.sh b/research/experiments/019-idle-links/ngtcp2/build.sh
new file mode 100755
index 0000000..e76017a
--- /dev/null
+++ b/research/experiments/019-idle-links/ngtcp2/build.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+# ngtcp2 1.25.0 with its OpenSSL 3.5 backend, into build/third (not kept in
+# the repository), and drain.c against it: build/third/ngtcp2-drain.
+set -e
+root=$(cd "$(dirname "$0")/../../../.." && pwd)
+third=$root/build/third
+if [ ! -f "$third/prefix/lib/libngtcp2.a" ]; then
+    mkdir -p "$third"
+    [ -d "$third/ngtcp2" ] || git clone -q --depth 1 --branch v1.25.0 https://github.com/ngtcp2/ngtcp2 "$third/ngtcp2"
+    mkdir -p "$third/ngtcp2/b"
+    (cd "$third/ngtcp2/b" && cmake -DENABLE_LIB_ONLY=ON -DENABLE_OPENSSL=ON -DENABLE_SHARED_LIB=OFF -DBUILD_TESTING=OFF \
+        -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$third/prefix" .. > /dev/null && make -s -j4 > /dev/null &&
+        make -s install > /dev/null)
+fi
+cc -O2 -g -std=c17 -Wall -Wextra -Werror -I"$third/prefix/include" "$(dirname "$0")/drain.c" \
+    "$third/prefix/lib/libngtcp2_crypto_ossl.a" "$third/prefix/lib/libngtcp2.a" -lssl -lcrypto -o "$third/ngtcp2-drain"