solver: split platform specific code

Signed-off-by: Sam Alba <samalba@users.noreply.github.com>

solver/socketprovider.go

@@ -3,11 +3,8 @@ package solver
 import (
 	"context"
 	"fmt"
-	"net"
 	"strings"
-	"time"
 
-	"github.com/Microsoft/go-winio"
 	"github.com/moby/buildkit/session"
 	"github.com/moby/buildkit/session/sshforward"
 	"google.golang.org/grpc"
@@ -41,20 +38,6 @@ func (sp *SocketProvider) CheckAgent(ctx context.Context, req *sshforward.CheckA
 	return &sshforward.CheckAgentResponse{}, nil
 }
 
-func dialStream(id string) (net.Conn, error) {
-	switch {
-	case strings.HasPrefix(id, unixPrefix):
-		id = strings.TrimPrefix(id, unixPrefix)
-		return net.DialTimeout("unix", id, time.Second)
-	case strings.HasPrefix(id, npipePrefix):
-		id = strings.TrimPrefix(id, npipePrefix)
-		dur := time.Second
-		return winio.DialPipe(id, &dur)
-	default:
-		return nil, fmt.Errorf("invalid socket forward key %s", id)
-	}
-}
-
 func (sp *SocketProvider) ForwardAgent(stream sshforward.SSH_ForwardAgentServer) error {
 	id := sshforward.DefaultID
 

solver/socketprovider_unix.go

@@ -0,0 +1,20 @@
+//go:build !windows
+// +build !windows
+
+package solver
+
+import (
+	"fmt"
+	"net"
+	"strings"
+	"time"
+)
+
+func dialStream(id string) (net.Conn, error) {
+	if !strings.HasPrefix(id, unixPrefix) {
+		return nil, fmt.Errorf("invalid socket forward key %s", id)
+	}
+
+	id = strings.TrimPrefix(id, unixPrefix)
+	return net.DialTimeout("unix", id, time.Second)
+}

solver/socketprovider_windows.go

@@ -0,0 +1,14 @@
+//go:build windows
+// +build windows
+
+package solver
+
+func dialStream(id string) (net.Conn, error) {
+	if !strings.HasPrefix(id, unixPrefix) {
+		return nil, fmt.Errorf("invalid socket forward key %s", id)
+	}
+
+	id = strings.TrimPrefix(id, npipePrefix)
+	dur := time.Second
+	return winio.DialPipe(id, &dur)
+}