Rudimentary start of HTTP servers

1 files changed, 51 insertions, 0 deletions

diff --git a/listeners.go b/listeners.go
new file mode 100644
index 000000000..962cb1d25
--- /dev/null
+++ b/listeners.go
@@ -0,0 +1,51 @@
+package caddy2
+
+import (
+	"fmt"
+	"net"
+	"sync/atomic"
+)
+
+// Listen returns a listener suitable for use in a Caddy module.
+func Listen(proto, addr string) (net.Listener, error) {
+	ln, err := net.Listen(proto, addr)
+	if err != nil {
+		return nil, err
+	}
+	return &fakeCloseListener{Listener: ln}, nil
+}
+
+// fakeCloseListener's Close() method is a no-op. This allows
+// stopping servers that are using the listener without giving
+// up the socket; thus, servers become hot-swappable while the
+// listener remains running. Listeners should be re-wrapped in
+// a new fakeCloseListener each time the listener is reused.
+type fakeCloseListener struct {
+	closed int32
+	net.Listener
+}
+
+// Accept accepts connections until Close() is called.
+func (fcl *fakeCloseListener) Accept() (net.Conn, error) {
+	if atomic.LoadInt32(&fcl.closed) == 1 {
+		return nil, ErrSwappingServers
+	}
+	return fcl.Listener.Accept()
+}
+
+// Close stops accepting new connections, but does not
+// actually close the underlying listener.
+func (fcl *fakeCloseListener) Close() error {
+	atomic.StoreInt32(&fcl.closed, 1)
+	return nil
+}
+
+// CloseUnderlying actually closes the underlying listener.
+func (fcl *fakeCloseListener) CloseUnderlying() error {
+	return fcl.Listener.Close()
+}
+
+// ErrSwappingServers is returned by fakeCloseListener when
+// Close() is called, indicating that it is pretending to
+// be closed so that the server using it can terminate.
+var ErrSwappingServers = fmt.Errorf("listener 'closed' 😉")