Reduce DNS resolver AwaitTimeout default value

- By default, don't delay a resolve as much if there's no response in the
  await case

psiphon/common/parameters/parameters.go

@@ -660,7 +660,7 @@ var defaultParameters = map[string]struct {
 	DNSResolverAttemptsPerServer:                {value: 2, minimum: 1},
 	DNSResolverAttemptsPerPreferredServer:       {value: 1, minimum: 1},
 	DNSResolverRequestTimeout:                   {value: 5 * time.Second, minimum: 100 * time.Millisecond, flags: useNetworkLatencyMultiplier},
-	DNSResolverAwaitTimeout:                     {value: 100 * time.Millisecond, minimum: 1 * time.Millisecond, flags: useNetworkLatencyMultiplier},
+	DNSResolverAwaitTimeout:                     {value: 10 * time.Millisecond, minimum: 1 * time.Millisecond, flags: useNetworkLatencyMultiplier},
 	DNSResolverPreresolvedIPAddressCIDRs:        {value: LabeledCIDRs{}},
 	DNSResolverPreresolvedIPAddressProbability:  {value: 0.0, minimum: 0.0},
 	DNSResolverAlternateServers:                 {value: []string{}},

psiphon/common/resolver/resolver.go

@@ -50,7 +50,7 @@ const (
 	resolverServersUpdateTTL         = 5 * time.Second
 	resolverDefaultAttemptsPerServer = 2
 	resolverDefaultRequestTimeout    = 5 * time.Second
-	resolverDefaultAwaitTimeout      = 100 * time.Millisecond
+	resolverDefaultAwaitTimeout      = 10 * time.Millisecond
 	resolverDefaultAnswerTTL         = 1 * time.Minute
 	resolverDNSPort                  = "53"
 	udpPacketBufferSize              = 1232
@@ -168,7 +168,7 @@ type ResolveParameters struct {
 
 	// AwaitTimeout specifies how long to await an additional response after
 	// the first response is received. This additional wait time applies only
-	// when there is no IPv4 or IPv6 response.
+	// when there is either no IPv4 or IPv6 response.
 	AwaitTimeout time.Duration
 
 	// PreresolvedIPAddress specifies an IP address result to be used in place

psiphon/common/resolver/resolver_test.go

@@ -110,7 +110,7 @@ func runTestMakeResolveParameters() error {
 	if resolverParams.AttemptsPerServer != 2 ||
 		resolverParams.AttemptsPerPreferredServer != 1 ||
 		resolverParams.RequestTimeout != 5*time.Second ||
-		resolverParams.AwaitTimeout != 100*time.Millisecond ||
+		resolverParams.AwaitTimeout != 10*time.Millisecond ||
 		!CIDRContainsIP(exampleIPv4CIDR, resolverParams.PreresolvedIPAddress) ||
 		resolverParams.AlternateDNSServer != "" ||
 		resolverParams.PreferAlternateDNSServer != false ||
@@ -153,7 +153,7 @@ func runTestMakeResolveParameters() error {
 	if resolverParams.AttemptsPerServer != 2 ||
 		resolverParams.AttemptsPerPreferredServer != 1 ||
 		resolverParams.RequestTimeout != 5*time.Second ||
-		resolverParams.AwaitTimeout != 100*time.Millisecond ||
+		resolverParams.AwaitTimeout != 10*time.Millisecond ||
 		resolverParams.PreresolvedIPAddress != "" ||
 		resolverParams.AlternateDNSServer != preferredAlternateDNSServerWithPort ||
 		resolverParams.PreferAlternateDNSServer != true ||
@@ -183,7 +183,7 @@ func runTestMakeResolveParameters() error {
 	if resolverParams.AttemptsPerServer != 2 ||
 		resolverParams.AttemptsPerPreferredServer != 1 ||
 		resolverParams.RequestTimeout != 5*time.Second ||
-		resolverParams.AwaitTimeout != 100*time.Millisecond ||
+		resolverParams.AwaitTimeout != 10*time.Millisecond ||
 		resolverParams.PreresolvedIPAddress != "" ||
 		resolverParams.AlternateDNSServer != alternateDNSServerWithPort ||
 		resolverParams.PreferAlternateDNSServer != false ||