c5efd45720
* experimental dnstap support into proxy * proxy reports dnstap errors * refactoring * add a message builder for less dnstap code * msg lint * context * proxy by DNS: dnstap comments * TapBuilder * resolves conflict * dnstap into ServeDNS * testing * more tests * `go lint` * doc update
96 lines
2.5 KiB
Go
96 lines
2.5 KiB
Go
package proxy
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import (
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"context"
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"crypto/tls"
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"log"
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"github.com/coredns/coredns/middleware/pkg/trace"
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"github.com/coredns/coredns/pb"
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"github.com/coredns/coredns/request"
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"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
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"github.com/miekg/dns"
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opentracing "github.com/opentracing/opentracing-go"
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"google.golang.org/grpc"
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"google.golang.org/grpc/credentials"
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)
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type grpcClient struct {
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dialOpts []grpc.DialOption
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clients map[string]pb.DnsServiceClient
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conns []*grpc.ClientConn
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upstream *staticUpstream
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}
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func newGrpcClient(tls *tls.Config, u *staticUpstream) *grpcClient {
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g := &grpcClient{upstream: u}
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if tls == nil {
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g.dialOpts = append(g.dialOpts, grpc.WithInsecure())
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} else {
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g.dialOpts = append(g.dialOpts, grpc.WithTransportCredentials(credentials.NewTLS(tls)))
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}
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g.clients = map[string]pb.DnsServiceClient{}
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return g
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}
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func (g *grpcClient) Exchange(ctx context.Context, addr string, state request.Request) (*dns.Msg, error) {
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msg, err := state.Req.Pack()
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if err != nil {
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return nil, err
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}
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reply, err := g.clients[addr].Query(ctx, &pb.DnsPacket{Msg: msg})
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if err != nil {
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return nil, err
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}
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d := new(dns.Msg)
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err = d.Unpack(reply.Msg)
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if err != nil {
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return nil, err
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}
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return d, nil
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}
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func (g *grpcClient) Transport() string { return "tcp" }
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func (g *grpcClient) Protocol() string { return "grpc" }
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func (g *grpcClient) OnShutdown(p *Proxy) error {
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g.clients = map[string]pb.DnsServiceClient{}
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for i, conn := range g.conns {
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err := conn.Close()
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if err != nil {
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log.Printf("[WARNING] Error closing connection %d: %s\n", i, err)
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}
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}
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g.conns = []*grpc.ClientConn{}
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return nil
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}
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func (g *grpcClient) OnStartup(p *Proxy) error {
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dialOpts := g.dialOpts
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if p.Trace != nil {
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if t, ok := p.Trace.(trace.Trace); ok {
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onlyIfParent := func(parentSpanCtx opentracing.SpanContext, method string, req, resp interface{}) bool {
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return parentSpanCtx != nil
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}
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intercept := otgrpc.OpenTracingClientInterceptor(t.Tracer(), otgrpc.IncludingSpans(onlyIfParent))
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dialOpts = append(dialOpts, grpc.WithUnaryInterceptor(intercept))
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} else {
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log.Printf("[WARNING] Wrong type for trace middleware reference: %s", p.Trace)
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}
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}
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for _, host := range g.upstream.Hosts {
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conn, err := grpc.Dial(host.Name, dialOpts...)
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if err != nil {
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log.Printf("[WARNING] Skipping gRPC host '%s' due to Dial error: %s\n", host.Name, err)
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} else {
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g.clients[host.Name] = pb.NewDnsServiceClient(conn)
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g.conns = append(g.conns, conn)
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}
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}
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return nil
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}
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