proxy: imp docs

README.md

@@ -24,7 +24,7 @@ A simple DNS proxy server that supports all existing DNS protocols including `DN
 
 ## How to build
 
-You will need go v1.16 or later.
+You will need Go v1.16 or later.
 
 ```shell
 $ go build -mod=vendor

proxy/helpers.go

@@ -66,7 +66,7 @@ func genSOA(request *dns.Msg, retry uint32) []dns.RR {
 	return []dns.RR{&soa}
 }
 
-// parseECS parses ECS option from m.
+// parseECS parses the EDNS client subnet option from m.
 func parseECS(m *dns.Msg) (addr net.IP, mask uint8, scope uint8) {
 	opt := m.IsEdns0()
 	if opt == nil {
@@ -92,15 +92,17 @@ func parseECS(m *dns.Msg) (addr net.IP, mask uint8, scope uint8) {
 	return nil, 0, 0
 }
 
-// setECS sets EDNS client subnet option into m.  It returns masked IP and mask
-// length.
+// setECS sets the EDNS client subnet option based on ip and scope into m.  It
+// returns masked IP and mask length.
 func setECS(m *dns.Msg, ip net.IP, scope uint8) (net.IP, uint8) {
 	const (
 		// defaultECSv4 is the default length of network mask for IPv4 address
 		// in EDNS client subnet option.
 		defaultECSv4 = 24
 		// defaultECSv6 is the default length of network mask for IPv6 address
-		// in EDNS client subnet option.
+		// in EDNS client subnet option.  The size of 7 bytes is chosen as a
+		// reasonable minimum since at least Google's public DNS refuses
+		// requests containing the options with longer network masks.
 		defaultECSv6 = 56
 	)
 

proxy/ratelimit.go

@@ -45,7 +45,7 @@ func (p *Proxy) isRatelimited(addr net.Addr) bool {
 	if len(p.RatelimitWhitelist) > 0 {
 		i := sort.SearchStrings(p.RatelimitWhitelist, ipStr)
 		if i < len(p.RatelimitWhitelist) && p.RatelimitWhitelist[i] == ipStr {
-			// Don't ratelimit if the ip is whitelisted.
+			// Don't ratelimit if the ip is allowlisted.
 			return false
 		}
 	}