Success path for fake tls is implemented

faketls/certificate_server.go

@@ -0,0 +1,91 @@
+package faketls
+
+import (
+	"bytes"
+	"container/ring"
+	"context"
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+	"time"
+
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/config"
+)
+
+type connectionServer struct {
+	nextWriteItem *ring.Ring
+	nextReadItem  *ring.Ring
+
+	ctx        context.Context
+	channelGet chan chan<- []byte
+}
+
+func (c *connectionServer) get() ([]byte, error) {
+	resp := make(chan []byte)
+	select {
+	case <-c.ctx.Done():
+		return nil, errors.New("context closed")
+	case c.channelGet <- resp:
+		return <-resp, nil
+	}
+}
+
+func (c *connectionServer) fetch() ([]byte, error) {
+	addr := net.JoinHostPort(config.C.CloakHost, strconv.Itoa(config.C.CloakPort))
+	conn, err := tls.Dial("tcp", addr, &tls.Config{InsecureSkipVerify: true}) // nolint: gosec
+
+	if err != nil {
+		return nil, fmt.Errorf("cannot connect to the masked host: %w", err)
+	}
+
+	defer conn.Close()
+
+	if err = conn.Handshake(); err != nil {
+		return nil, fmt.Errorf("cannot perform tls handshake: %w", err)
+	}
+
+	certificates := conn.ConnectionState().PeerCertificates
+	if len(certificates) == 0 {
+		return nil, errors.New("no certificates is found")
+	}
+
+	var buf bytes.Buffer
+
+	for _, v := range certificates {
+		buf.Write(v.Raw)
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (c *connectionServer) run(tickEvery time.Duration) {
+	logger := zap.S().Named("tls-connection-server")
+
+	ticker := time.NewTicker(tickEvery)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-c.ctx.Done():
+			return
+		case resp := <-c.channelGet:
+			resp <- c.nextReadItem.Value.([]byte)
+			close(resp)
+
+			c.nextReadItem = c.nextReadItem.Next()
+		case <-ticker.C:
+			cert, err := c.fetch()
+			switch err {
+			case nil:
+				c.nextWriteItem.Value = cert
+				c.nextWriteItem = c.nextWriteItem.Next()
+			default:
+				logger.Warnw("cannot fetch certificates", "error", err)
+			}
+		}
+	}
+}