main: upstream mode

README.md

@@ -17,7 +17,7 @@ it can work as a `DNS-over-HTTPS`, `DNS-over-TLS` or `DNS-over-QUIC` server.
   - [Encrypted DNS server](#encrypted-dns-server)
   - [Additional features](#additional-features)
   - [DNS64 server](#dns64-server)
-  - [Fastest addr + cache-min-ttl](#fastest-addr--cache-min-ttl)
+  - [Fastest addr + cache-min-ttl](#fastest-addr-upstream-mode--cache-min-ttl)
   - [Specifying upstreams for domains](#specifying-upstreams-for-domains)
   - [EDNS Client Subnet](#edns-client-subnet)
   - [Bogus NXDomain](#bogus-nxdomain)
@@ -86,8 +86,7 @@ Application Options:
       --insecure                   Disable secure TLS certificate validation
       --ipv6-disabled              If specified, all AAAA requests will be replied with NoError RCode and empty answer
       --http3                      Enable HTTP/3 support
-      --all-servers                If specified, parallel queries to all configured upstream servers are enabled
-      --fastest-addr               Respond to A or AAAA requests only with the fastest IP address
+      --upstream-mode              If specified, determines the upstream usage logic.
       --cache-optimistic           If specified, optimistic DNS cache is enabled
       --cache                      If specified, DNS cache is enabled
       --refuse-any                 If specified, refuse ANY requests
@@ -264,20 +263,22 @@ specified and enabled if DNS64 is enabled.
 
 [wkp]: https://datatracker.ietf.org/doc/html/rfc6052#section-2.1
 
-### Fastest addr + cache-min-ttl
+### Fastest addr upstream mode + cache-min-ttl
 
 This option would be useful to the users with problematic network connection.
-In this mode, `dnsproxy` would detect the fastest IP address among all that were returned,
-and it will return only it.
+In this mode, `dnsproxy` would detect the fastest IP address among all that were
+returned, and it will return only it.
 
-Additionally, for those with problematic network connection, it makes sense to override `cache-min-ttl`.
-In this case, `dnsproxy` will make sure that DNS responses are cached for at least the specified amount of time.
+Additionally, for those with problematic network connection, it makes sense to
+override `cache-min-ttl`.  In this case, `dnsproxy` will make sure that DNS
+responses are cached for at least the specified amount of time.
 
 It makes sense to run it with multiple upstream servers only.
 
-Run a DNS proxy with two upstreams, min-TTL set to 10 minutes, fastest address detection is enabled:
+Run a DNS proxy with two upstreams, min-TTL set to 10 minutes, fastest address
+detection is enabled:
 ```
-./dnsproxy -u 8.8.8.8 -u 1.1.1.1 --cache --cache-min-ttl=600 --fastest-addr
+./dnsproxy -u 8.8.8.8 -u 1.1.1.1 --cache --cache-min-ttl=600 --upstream-mode=fastest-addr
 ```
 
  who run `dnsproxy` with multiple upstreams

main.go

@@ -66,6 +66,9 @@ type Options struct {
 	// EDNSAddr is the custom EDNS Client Address to send.
 	EDNSAddr string `yaml:"edns-addr" long:"edns-addr" description:"Send EDNS Client Address"`
 
+	// UpstreamMode determines the logic through which upstreams will be used.
+	UpstreamMode string `yaml:"upstream-mode" long:"upstream-mode" description:"" optional:"yes" optional-value:"load_balance"`
+
 	// ListenAddrs is the list of server's listen addresses.
 	ListenAddrs []string `yaml:"listen-addrs" short:"l" long:"listen" description:"Listening addresses"`
 
@@ -174,15 +177,6 @@ type Options struct {
 	// It enables HTTP/3 support for both the DoH upstreams and the DoH server.
 	HTTP3 bool `yaml:"http3" long:"http3" description:"Enable HTTP/3 support" optional:"yes" optional-value:"false"`
 
-	// AllServers makes server to query all configured upstream servers in
-	// parallel.
-	AllServers bool `yaml:"all-servers" long:"all-servers" description:"If specified, parallel queries to all configured upstream servers are enabled" optional:"yes" optional-value:"true"`
-
-	// FastestAddress controls whether the server should respond to A or AAAA
-	// requests only with the fastest IP address detected by ICMP response time
-	// or TCP connection time.
-	FastestAddress bool `yaml:"fastest-addr" long:"fastest-addr" description:"Respond to A or AAAA requests only with the fastest IP address" optional:"yes" optional-value:"true"`
-
 	// CacheOptimistic, if set to true, enables the optimistic DNS cache. That
 	// means that cached results will be served even if their cache TTL has
 	// already expired.
@@ -555,14 +549,12 @@ func (opts *Options) initUpstreams(
 		config.Fallbacks = fallbacks
 	}
 
-	if opts.AllServers {
-		config.UpstreamMode = proxy.UpstreamModeParallel
-	} else if opts.FastestAddress {
-		config.UpstreamMode = proxy.UpstreamModeFastestAddr
-	} else {
-		config.UpstreamMode = proxy.UpstreamModeLoadBalance
+	if opts.UpstreamMode != "" {
+		return config.UpstreamMode.UnmarshalText([]byte(opts.UpstreamMode))
 	}
 
+	config.UpstreamMode = proxy.UpstreamModeLoadBalance
+
 	return nil
 }
 

proxy/upstreammode.go

@@ -9,8 +9,17 @@ import (
 type UpstreamMode string
 
 const (
+	// UpstreamModeLoadBalance is the default upstream mode.  It balances the
+	// upstreams load.
 	UpstreamModeLoadBalance UpstreamMode = "load_balance"
-	UpstreamModeParallel    UpstreamMode = "parallel"
+
+	// UpstreamModeParallel makes server to query all configured upstream
+	// servers in parallel.
+	UpstreamModeParallel UpstreamMode = "parallel"
+
+	// UpstreamModeFastestAddr controls whether the server should respond to A
+	// or AAAA requests only with the fastest IP address detected by ICMP
+	// response time or TCP connection time.
 	UpstreamModeFastestAddr UpstreamMode = "fastest_addr"
 )