Merge bradfitz's tcpproxy codebase with the software formerly known as tlsrouter.

Brad's code will be the place for future development, and the base for the binary
formerly known as tlsrouter. This merge is the first step towards converging the
codebases.

1 files changed, 103 insertions, 0 deletions

diff --git a/listener.go b/listener.go
new file mode 100644
index 0000000..2fd29eb
--- /dev/null
+++ b/listener.go
@@ -0,0 +1,103 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tcpproxy
+
+import (
+	"io"
+	"net"
+	"sync"
+)
+
+// TargetListener implements both net.Listener and Target.
+// Matched Targets become accepted connections.
+type TargetListener struct {
+	Address string // Address is the string reported by TargetListener.Addr().String().
+
+	mu       sync.Mutex
+	cond     *sync.Cond
+	closed   bool
+	nextConn net.Conn
+}
+
+var (
+	_ net.Listener = (*TargetListener)(nil)
+	_ Target       = (*TargetListener)(nil)
+)
+
+func (tl *TargetListener) lock() {
+	tl.mu.Lock()
+	if tl.cond == nil {
+		tl.cond = sync.NewCond(&tl.mu)
+	}
+}
+
+type tcpAddr string
+
+func (a tcpAddr) Network() string { return "tcp" }
+func (a tcpAddr) String() string  { return string(a) }
+
+func (tl *TargetListener) Addr() net.Addr { return tcpAddr(tl.Address) }
+
+func (tl *TargetListener) Close() error {
+	tl.lock()
+	if tl.closed {
+		tl.mu.Unlock()
+		return nil
+	}
+	tl.closed = true
+	tl.mu.Unlock()
+	tl.cond.Broadcast()
+	return nil
+}
+
+// HandleConn implements the Target interface. It blocks until tl is
+// closed or another goroutine has called Accept and received c.
+func (tl *TargetListener) HandleConn(c net.Conn) {
+	tl.lock()
+	defer tl.mu.Unlock()
+	for tl.nextConn != nil && !tl.closed {
+		tl.cond.Wait()
+	}
+	if tl.closed {
+		c.Close()
+		return
+	}
+	tl.nextConn = c
+	tl.cond.Broadcast() // Signal might be sufficient; verify.
+	for tl.nextConn == c && !tl.closed {
+		tl.cond.Wait()
+	}
+	if tl.closed {
+		c.Close()
+		return
+	}
+}
+
+func (tl *TargetListener) Accept() (net.Conn, error) {
+	tl.lock()
+	for tl.nextConn == nil && !tl.closed {
+		tl.cond.Wait()
+	}
+	if tl.closed {
+		tl.mu.Unlock()
+		return nil, io.EOF
+	}
+	c := tl.nextConn
+	tl.nextConn = nil
+	tl.mu.Unlock()
+	tl.cond.Broadcast() // Signal might be sufficient; verify.
+
+	return c, nil
+}