config: set user-agent for doh

intra/doh/doh.go

@@ -49,6 +49,7 @@ import (
 	"github.com/celzero/firestack/intra/ipn"
 	"github.com/celzero/firestack/intra/log"
 	"github.com/celzero/firestack/intra/protect"
+	"github.com/celzero/firestack/intra/settings"
 	"github.com/celzero/firestack/intra/xdns"
 	"github.com/cloudflare/odoh-go"
 	"github.com/miekg/dns"
@@ -662,7 +663,9 @@ func (t *transport) asDohRequest(msg *dns.Msg) (req *http.Request, err error) {
 	}
 	req.Header.Set("content-type", dohmimetype)
 	req.Header.Set("accept", dohmimetype)
-	req.Header.Set("user-agent", "")
+	if settings.SetUserAgentForDoH.Load() {
+		req.Header.Set("user-agent", "Intra")
+	}
 	return
 }
 

intra/settings/config.go

@@ -103,6 +103,10 @@ var EndpointIndependentFiltering = atomic.Bool{}
 // for undelegated domains.
 var SystemDNSForUndelegatedDomains = atomic.Bool{}
 
+// SetUserAgentForDoH is a global flag to set User-Agent for DoH requests
+// to "Intra".
+var SetUserAgentForDoH = atomic.Bool{}
+
 // L3 returns the string'd repr of engine.
 func L3(engine int) string {
 	switch engine {

intra/tun2socks.go

@@ -122,6 +122,7 @@ func UndelegatedDomains(useSystemDNS bool) {
 func Transparency(eim, eif bool) {
 	settings.EndpointIndependentMapping.Store(eim)
 	settings.EndpointIndependentFiltering.Store(eif)
+	settings.SetUserAgentForDoH.Store(eim || eif)
 	log.I("tun: eim? %t / eif? %t", eim, eif)
 }