russell@unturf.com 9934133dcf whitepaper: 312 sites / 151 ecosystems — wave2+3 defect tables and PDF rebuild

Add 88 new defect entries to HIGH and MEDIUM tables:
  HIGH: mysql-0001/0002, mariadb-0001, redis-0001/0002, valkey-0001/0002, openvpn-0001,
        vlc-0001, prometheus-0001, otel-collector-0001, cockroachdb-0001..0004,
        tidb-0001..0008, kubernetes-0001/0002, go-0001, kotlin-0002, scala-0001,
        allegro5-0001, sdl2-0001, grafana-0001, clickhouse-0001, duckdb-0001,
        mongodb-0001, envoy-0001, istio-0001, cilium-0001, linkerd2-0001,
        linux-0001/0002/0003, tor-0002/0003, curl-0001, julia-0001, lua-0001,
        perl5-0001, nats-0001, spring-0003/0004, tomcat-0001, onos-0002, odl-0002

  MEDIUM: helm-0001, mariadb-0002, openssl-0001/0002, memcached-0001,
          cassandra-0001..0004, flink-0001, storm-0001/0002, zookeeper-0001..0003,
          pip-0001, gradle-0001, nginx-0001, haproxy-0001, caddy-0001, varnish-0001,
          ffmpeg-0001, gstreamer-0001, raylib-0001, love2d-0001, php-0001/0002,
          r-source-0001, cpython-0002, ruby-0001, rabbitmq-0003/0004, activemq-0001,
          ovs-0001, onos-0003, odl-0002, jetty-0001

PDF: 976K

2026-03-27 15:23:43 -04:00

1.8 KiB

Raw Blame History

caddy-0001: hostByHashing full pool scan per request

Target: caddy File: modules/caddyhttp/reverseproxy/selectionpolicies.go Function: hostByHashing Lines: 842–851 Severity: MEDIUM CWE: CWE-407 (Inefficient Algorithmic Complexity)

Description

Caddy's hash-based upstream selection policies (URI hash, header hash, cookie hash, query hash, client-IP hash) all funnel through hostByHashing, which iterates over every upstream in the pool, hashing each one with xxhash:

for _, up := range pool {
    if !up.Available() {
        continue
    }
    h := hash(up.String() + s)   // xxhash per upstream per request
    if h > highestHash {
        highestHash = h
        upstream = up
    }
}

With N upstreams and R requests/second, total xxhash calls = O(N × R). Each xxhash call allocates a new xxhash.New() hasher (line 856–859).

The pool is stable between config reloads; the available subset changes only when health checks flip. The per-request rehash of stable upstreams is wasted work.

Impact

50 upstreams × 50 000 RPS = 2 500 000 xxhash calls/second with allocations.
Available-pool filtering (!up.Available()) still requires touching every upstream struct, causing cache-line pressure.

Fix

Cache the xxhash of each upstream's string at provision time (up.String() is stable). Store upstreamHash uint64 on the Upstream struct. At request time: h = cachedHash XOR hash(s) — one hash call per request regardless of pool size. Recompute the combined hash only when pool membership changes (config reload).

For Available() filtering: maintain an atomic slice of available-upstream indices updated by the health-check goroutine. Selection scans only available entries.

Patch

See defects/caddy/patch/caddy-0001.patch

Unit Test

See defects/caddy/unit/CaddyHostByHashingAlgorithmTest.java

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