release prep: 1.8.1 (#581)

Version to 1.8.1 in the binary, the config template, and the README's
docker/Configuration headers; the benchmark section stays at the
last-measured release by policy.

The contrib config is regenerated from the template and verified
byte-identical to what the binary writes. doc.go's feature list cited
RFC 7816, obsoleted by RFC 9156 in 2021 — the config and README were
already updated when the minimization mechanism moved to the RFC's
probe-count budget; this catches the last reference. One modernization
in the TTL clamp (max over an if).

The prefetch-claim release considered for this release turned out to be
already correct: processPrefetch releases the claim on every exit path
via defer, and TestPrefetchWorkerReleasesClaimOnError pins it.

Author: semihalev

README.md

@@ -45,7 +45,7 @@ $ docker run -d --name sdns -p 53:53 -p 53:53/udp ghcr.io/semihalev/sdns:latest
 Pin to a specific version (recommended for production):
 
 ```shell
-$ docker run -d --name sdns -p 53:53 -p 53:53/udp ghcr.io/semihalev/sdns:1.8.0
+$ docker run -d --name sdns -p 53:53 -p 53:53/udp ghcr.io/semihalev/sdns:1.8.1
 ```
 
 #### Docker Compose
@@ -136,7 +136,7 @@ example.com.		0	CH	HINFO	"Host" "IPv6:[2001:500:8f::53]:53 rtt:147ms health:[GOO
 example.com.		0	CH	HINFO	"Host" "IPv6:[2001:500:8d::53]:53 rtt:148ms health:[GOOD]"
 ```
 
-## Configuration (v1.8.0)
+## Configuration (v1.8.1)
 
 | Key                  | Description                                                                                                         |
 | -------------------- | ------------------------------------------------------------------------------------------------------------------- |

config/config.go

@@ -18,7 +18,7 @@ import (
 	"github.com/semihalev/zlog/v2"
 )
 
-const configver = "1.8.0"
+const configver = "1.8.1"
 
 // Config type.
 type Config struct {

contrib/linux/sdns.conf

@@ -1,6 +1,6 @@
 
 # Configuration file version (not SDNS version)
-version = "1.8.0"
+version = "1.8.1"
 
 # ============================
 # Basic Server Configuration

doc.go

@@ -16,7 +16,7 @@ metrics and operational endpoints (blocklist management, cache purge).
   - Iterative recursive resolution with DNSSEC validation, NSEC/NSEC3
     denial-of-existence proofs, and RFC 5011 automatic root trust-anchor
     maintenance.
-  - QNAME minimization (RFC 7816) for query privacy.
+  - QNAME minimization (RFC 9156) for query privacy.
   - High-performance caching: positive and negative caches, prefetch of
     popular entries, and EDNS Client Subnet (ECS, RFC 7871) aware keying.
   - Forwarding to upstream resolvers over UDP, TCP, DoT, and DoH.

middleware/cache/cache.go

@@ -1815,10 +1815,7 @@ func clampTTLsToCut(res *dns.Msg, cutUntil time.Time) {
 	if cutUntil.IsZero() {
 		return
 	}
-	lease := time.Until(cutUntil)
-	if lease < 0 {
-		lease = 0
-	}
+	lease := max(time.Until(cutUntil), 0)
 	leaseSecs := uint32(lease.Seconds())
 	clamp := func(rrs []dns.RR) {
 		for _, rr := range rrs {

sdns.go

@@ -21,7 +21,7 @@ import (
 	"github.com/spf13/cobra"
 )
 
-const version = "1.8.0"
+const version = "1.8.1"
 
 var (
 	cfgPath    string