Pull request: close-upstream-conf

Merge in DNS/dnsproxy from close-upstream-conf to master

Squashed commit of the following:

commit 69175c3
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Oct 25 17:23:12 2022 +0300

    proxy: add todo

commit d5d1996
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Oct 25 17:06:59 2022 +0300

    proxy: fix docs

commit d815679
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Oct 25 17:05:04 2022 +0300

    proxy: close upstream conf beter

proxy/proxy.go

@@ -203,15 +203,16 @@ func (p *Proxy) Start() (err error) {
 	return nil
 }
 
-// closeAll closes all elements in the toClose slice and if there's any error
-// appends it to the errs slice.
-func closeAll[T io.Closer](toClose []T, errs *[]error) {
-	for _, c := range toClose {
+// closeAll closes all closers and appends the occurred errors to errs.
+func closeAll[C io.Closer](errs []error, closers ...C) (appended []error) {
+	for _, c := range closers {
 		err := c.Close()
 		if err != nil {
-			*errs = append(*errs, err)
+			errs = append(errs, err)
 		}
 	}
+
+	return errs
 }
 
 // Stop stops the proxy server including all its listeners
@@ -225,44 +226,42 @@ func (p *Proxy) Stop() error {
 		return nil
 	}
 
-	errs := []error{}
-
-	closeAll(p.tcpListen, &errs)
+	errs := closeAll(nil, p.tcpListen...)
 	p.tcpListen = nil
 
-	closeAll(p.udpListen, &errs)
+	errs = closeAll(errs, p.udpListen...)
 	p.udpListen = nil
 
-	closeAll(p.tlsListen, &errs)
+	errs = closeAll(errs, p.tlsListen...)
 	p.tlsListen = nil
 
 	if p.httpsServer != nil {
-		closeAll([]io.Closer{p.httpsServer}, &errs)
+		errs = closeAll(errs, p.httpsServer)
 		p.httpsServer = nil
 
 		// No need to close these since they're closed by httpsServer.Close().
 		p.httpsListen = nil
 	}
 
 	if p.h3Server != nil {
-		closeAll([]io.Closer{p.h3Server}, &errs)
+		errs = closeAll(errs, p.h3Server)
 		p.h3Server = nil
 	}
 
-	closeAll(p.h3Listen, &errs)
+	errs = closeAll(errs, p.h3Listen...)
 	p.h3Listen = nil
 
-	closeAll(p.quicListen, &errs)
+	errs = closeAll(errs, p.quicListen...)
 	p.quicListen = nil
 
-	closeAll(p.dnsCryptUDPListen, &errs)
+	errs = closeAll(errs, p.dnsCryptUDPListen...)
 	p.dnsCryptUDPListen = nil
 
-	closeAll(p.dnsCryptTCPListen, &errs)
+	errs = closeAll(errs, p.dnsCryptTCPListen...)
 	p.dnsCryptTCPListen = nil
 
 	if p.UpstreamConfig != nil {
-		closeAll([]io.Closer{p.UpstreamConfig}, &errs)
+		errs = closeAll(errs, p.UpstreamConfig)
 	}
 
 	p.started = false

proxy/upstreams.go

@@ -3,6 +3,7 @@ package proxy
 import (
 	"fmt"
 	"io"
+	"sort"
 	"strings"
 
 	"github.com/AdguardTeam/dnsproxy/upstream"
@@ -224,8 +225,23 @@ func (uc *UpstreamConfig) getUpstreamsForDomain(host string) (ups []upstream.Ups
 
 // Close implements the io.Closer interface for *UpstreamConfig.
 func (uc *UpstreamConfig) Close() (err error) {
-	closeErrs := []error{}
-	closeAll(uc.Upstreams, &closeErrs)
+	closeErrs := closeAll(nil, uc.Upstreams...)
+
+	for _, specUps := range []map[string][]upstream.Upstream{
+		uc.DomainReservedUpstreams,
+		uc.SpecifiedDomainUpstreams,
+	} {
+		domains := make([]string, 0, len(specUps))
+		for domain := range specUps {
+			domains = append(domains, domain)
+		}
+		// TODO(e.burkov):  Use functions from golang.org/x/exp.
+		sort.Stable(sort.StringSlice(domains))
+
+		for _, domain := range domains {
+			closeErrs = closeAll(closeErrs, specUps[domain]...)
+		}
+	}
 
 	if len(closeErrs) > 0 {
 		return errors.List("failed to close some upstreams", closeErrs...)