1 files changed, 129 insertions, 0 deletions
diff --git a/vendor/github.com/rootless-containers/rootlesskit/pkg/port/builtin/msg/msg.go b/vendor/github.com/rootless-containers/rootlesskit/pkg/port/builtin/msg/msg.go
new file mode 100644
index 000000000..c603f473a
--- /dev/null
+++ b/vendor/github.com/rootless-containers/rootlesskit/pkg/port/builtin/msg/msg.go
@@ -0,0 +1,129 @@
+package msg
+
+import (
+	"net"
+	"time"
+
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+
+	"github.com/rootless-containers/rootlesskit/pkg/msgutil"
+	"github.com/rootless-containers/rootlesskit/pkg/port"
+)
+
+const (
+	RequestTypeInit    = "init"
+	RequestTypeConnect = "connect"
+)
+
+// Request and Response are encoded as JSON with uint32le length header.
+type Request struct {
+	Type  string // "init" or "connect"
+	Proto string // "tcp" or "udp"
+	Port  int
+}
+
+// Reply may contain FD as OOB
+type Reply struct {
+	Error string
+}
+
+// Initiate sends "init" request to the child UNIX socket.
+func Initiate(c *net.UnixConn) error {
+	req := Request{
+		Type: RequestTypeInit,
+	}
+	if _, err := msgutil.MarshalToWriter(c, &req); err != nil {
+		return err
+	}
+	if err := c.CloseWrite(); err != nil {
+		return err
+	}
+	var rep Reply
+	if _, err := msgutil.UnmarshalFromReader(c, &rep); err != nil {
+		return err
+	}
+	return c.CloseRead()
+}
+
+// ConnectToChild connects to the child UNIX socket, and obtains TCP or UDP socket FD
+// that corresponds to the port spec.
+func ConnectToChild(c *net.UnixConn, spec port.Spec) (int, error) {
+	req := Request{
+		Type:  RequestTypeConnect,
+		Proto: spec.Proto,
+		Port:  spec.ChildPort,
+	}
+	if _, err := msgutil.MarshalToWriter(c, &req); err != nil {
+		return 0, err
+	}
+	if err := c.CloseWrite(); err != nil {
+		return 0, err
+	}
+	oobSpace := unix.CmsgSpace(4)
+	oob := make([]byte, oobSpace)
+	_, oobN, _, _, err := c.ReadMsgUnix(nil, oob)
+	if err != nil {
+		return 0, err
+	}
+	if oobN != oobSpace {
+		return 0, errors.Errorf("expected OOB space %d, got %d", oobSpace, oobN)
+	}
+	oob = oob[:oobN]
+	fd, err := parseFDFromOOB(oob)
+	if err != nil {
+		return 0, err
+	}
+	if err := c.CloseRead(); err != nil {
+		return 0, err
+	}
+	return fd, nil
+}
+
+// ConnectToChildWithSocketPath wraps ConnectToChild
+func ConnectToChildWithSocketPath(socketPath string, spec port.Spec) (int, error) {
+	var dialer net.Dialer
+	conn, err := dialer.Dial("unix", socketPath)
+	if err != nil {
+		return 0, err
+	}
+	defer conn.Close()
+	c := conn.(*net.UnixConn)
+	return ConnectToChild(c, spec)
+}
+
+// ConnectToChildWithRetry retries ConnectToChild every (i*5) milliseconds.
+func ConnectToChildWithRetry(socketPath string, spec port.Spec, retries int) (int, error) {
+	for i := 0; i < retries; i++ {
+		fd, err := ConnectToChildWithSocketPath(socketPath, spec)
+		if i == retries-1 && err != nil {
+			return 0, err
+		}
+		if err == nil {
+			return fd, err
+		}
+		// TODO: backoff
+		time.Sleep(time.Duration(i*5) * time.Millisecond)
+	}
+	// NOT REACHED
+	return 0, errors.New("reached max retry")
+}
+
+func parseFDFromOOB(oob []byte) (int, error) {
+	scms, err := unix.ParseSocketControlMessage(oob)
+	if err != nil {
+		return 0, err
+	}
+	if len(scms) != 1 {
+		return 0, errors.Errorf("unexpected scms: %v", scms)
+	}
+	scm := scms[0]
+	fds, err := unix.ParseUnixRights(&scm)
+	if err != nil {
+		return 0, err
+	}
+	if len(fds) != 1 {
+		return 0, errors.Errorf("unexpected fds: %v", fds)
+	}
+	return fds[0], nil
+}