vendor: update moby/buildkit

Update modules:

  go mod edit -require github.com/moby/buildkit@master
  go mod tidy -compat=1.17 && ./hack/update-vendor

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/moby/buildkit/client/connhelper/ssh/ssh.go

@@ -0,0 +1,78 @@
+// Package ssh provides connhelper for ssh://<SSH URL>
+package ssh
+
+import (
+	"context"
+	"net"
+	"net/url"
+
+	"github.com/docker/cli/cli/connhelper/commandconn"
+	"github.com/moby/buildkit/client/connhelper"
+	"github.com/pkg/errors"
+)
+
+func init() {
+	connhelper.Register("ssh", Helper)
+}
+
+// Helper returns helper for connecting through an SSH URL.
+func Helper(u *url.URL) (*connhelper.ConnectionHelper, error) {
+	sp, err := SpecFromURL(u)
+	if err != nil {
+		return nil, err
+	}
+	return &connhelper.ConnectionHelper{
+		ContextDialer: func(ctx context.Context, addr string) (net.Conn, error) {
+			args := []string{}
+			if sp.User != "" {
+				args = append(args, "-l", sp.User)
+			}
+			if sp.Port != "" {
+				args = append(args, "-p", sp.Port)
+			}
+			args = append(args, "--", sp.Host)
+			args = append(args, "buildctl")
+			if socket := sp.Socket; socket != "" {
+				args = append(args, "--addr", "unix://"+socket)
+			}
+			args = append(args, "dial-stdio")
+			// using background context because context remains active for the duration of the process, after dial has completed
+			return commandconn.New(context.Background(), "ssh", args...)
+		},
+	}, nil
+}
+
+// Spec
+type Spec struct {
+	User   string
+	Host   string
+	Port   string
+	Socket string
+}
+
+// SpecFromURL creates Spec from URL.
+// URL is like ssh://<user>@host:<port>
+// Only <host> part is mandatory.
+func SpecFromURL(u *url.URL) (*Spec, error) {
+	sp := Spec{
+		Host:   u.Hostname(),
+		Port:   u.Port(),
+		Socket: u.Path,
+	}
+	if user := u.User; user != nil {
+		sp.User = user.Username()
+		if _, ok := user.Password(); ok {
+			return nil, errors.New("plain-text password is not supported")
+		}
+	}
+	if sp.Host == "" {
+		return nil, errors.Errorf("no host specified")
+	}
+	if u.RawQuery != "" {
+		return nil, errors.Errorf("extra query after the host: %q", u.RawQuery)
+	}
+	if u.Fragment != "" {
+		return nil, errors.Errorf("extra fragment after the host: %q", u.Fragment)
+	}
+	return &sp, nil
+}