Removed pooled server and add plain resolver

resolver/resolver-plain.go

@@ -0,0 +1,92 @@
+package resolver
+
+import (
+	"context"
+	"net"
+	"time"
+
+	"github.com/miekg/dns"
+	"github.com/safing/portbase/log"
+	"github.com/safing/portmaster/netenv"
+)
+
+var (
+	defaultClientTTL      = 5 * time.Minute
+	defaultRequestTimeout = 3 * time.Second // dns query
+	defaultConnectTimeout = 5 * time.Second // tcp/tls
+)
+
+// PlainResolver is a resolver using plain DNS.
+type PlainResolver struct {
+	BasicResolverConn
+}
+
+// NewPlainResolver returns a new TPCResolver.
+func NewPlainResolver(resolver *Resolver) *PlainResolver {
+	return &PlainResolver{
+		BasicResolverConn: BasicResolverConn{
+			resolver: resolver,
+		},
+	}
+}
+
+// Query executes the given query against the resolver.
+func (pr *PlainResolver) Query(ctx context.Context, q *Query) (*RRCache, error) {
+	// create query
+	dnsQuery := new(dns.Msg)
+	dnsQuery.SetQuestion(q.FQDN, uint16(q.QType))
+
+	// get timeout from context and config
+	var timeout time.Duration
+	if deadline, ok := ctx.Deadline(); !ok {
+		timeout = 0
+	} else {
+		timeout = time.Until(deadline)
+	}
+	if timeout > defaultRequestTimeout {
+		timeout = defaultRequestTimeout
+	}
+
+	// create client
+	dnsClient := &dns.Client{
+		Timeout: timeout,
+		Dialer: &net.Dialer{
+			Timeout:   timeout,
+			LocalAddr: getLocalAddr("udp"),
+		},
+	}
+
+	// query server
+	reply, ttl, err := dnsClient.Exchange(dnsQuery, pr.resolver.ServerAddress)
+	log.Tracer(ctx).Tracef("resolver: query took %s", ttl)
+	// error handling
+	if err != nil {
+		// Hint network environment at failed connection if err is not a timeout.
+		if nErr, ok := err.(net.Error); ok && !nErr.Timeout() {
+			netenv.ReportFailedConnection()
+		}
+
+		return nil, err
+	}
+
+	// check if blocked
+	if pr.resolver.IsBlockedUpstream(reply) {
+		return nil, &BlockedUpstreamError{pr.resolver.GetName()}
+	}
+
+	// hint network environment at successful connection
+	netenv.ReportSuccessfulConnection()
+
+	newRecord := &RRCache{
+		Domain:      q.FQDN,
+		Question:    q.QType,
+		Answer:      reply.Answer,
+		Ns:          reply.Ns,
+		Extra:       reply.Extra,
+		Server:      pr.resolver.Server,
+		ServerScope: pr.resolver.ServerIPScope,
+	}
+
+	// TODO: check if reply.Answer is valid
+	return newRecord, nil
+}