replacing IsDomainName linkname

common/bufio/copy.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"io"
 	"net"
-	"syscall"
 
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/buf"
@@ -59,14 +58,10 @@ func CopyWithIncreateBuffer(destination io.Writer, source io.Reader, increaseBuf
 }
 
 func CopyWithCounters(destination io.Writer, source io.Reader, originSource io.Reader, readCounters []N.CountFunc, writeCounters []N.CountFunc, increaseBufferAfter int64, batchSize int) (n int64, err error) {
-	srcSyscallConn, srcIsSyscall := source.(syscall.Conn)
-	dstSyscallConn, dstIsSyscall := destination.(syscall.Conn)
-	if srcIsSyscall && dstIsSyscall {
-		var handled bool
-		handled, n, err = copyDirect(srcSyscallConn, dstSyscallConn, readCounters, writeCounters)
-		if handled {
-			return
-		}
+	var handled bool
+	handled, n, err = copyDirect(source, destination, readCounters, writeCounters)
+	if handled {
+		return
 	}
 	return CopyExtended(originSource, NewExtendedWriter(destination), NewExtendedReader(source), readCounters, writeCounters, increaseBufferAfter, batchSize)
 }

common/bufio/copy_direct.go

@@ -3,23 +3,22 @@ package bufio
 import (
 	"errors"
 	"io"
-	"syscall"
 
 	"github.com/sagernet/sing/common/buf"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 )
 
-func copyDirect(source syscall.Conn, destination syscall.Conn, readCounters []N.CountFunc, writeCounters []N.CountFunc) (handed bool, n int64, err error) {
-	rawSource, err := source.SyscallConn()
-	if err != nil {
+func copyDirect(source io.Reader, destination io.Writer, readCounters []N.CountFunc, writeCounters []N.CountFunc) (handed bool, n int64, err error) {
+	if !N.SyscallAvailableForRead(source) || !N.SyscallAvailableForWrite(destination) {
 		return
 	}
-	rawDestination, err := destination.SyscallConn()
-	if err != nil {
+	sourceReader, sourceConn := N.SyscallConnForRead(source)
+	destinationWriter, destinationConn := N.SyscallConnForWrite(destination)
+	if sourceConn == nil || destinationConn == nil {
 		return
 	}
-	handed, n, err = splice(rawSource, rawDestination, readCounters, writeCounters)
+	handed, n, err = splice(sourceConn, sourceReader, destinationConn, destinationWriter, readCounters, writeCounters)
 	return
 }
 

common/bufio/splice_linux.go

@@ -11,7 +11,7 @@ import (
 
 const maxSpliceSize = 1 << 20
 
-func splice(source syscall.RawConn, destination syscall.RawConn, readCounters []N.CountFunc, writeCounters []N.CountFunc) (handed bool, n int64, err error) {
+func splice(source syscall.RawConn, sourceReader N.SyscallReader, destination syscall.RawConn, destinationWriter N.SyscallWriter, readCounters []N.CountFunc, writeCounters []N.CountFunc) (handed bool, n int64, err error) {
 	handed = true
 	var pipeFDs [2]int
 	err = unix.Pipe2(pipeFDs[:], syscall.O_CLOEXEC|syscall.O_NONBLOCK)
@@ -20,12 +20,14 @@ func splice(source syscall.RawConn, destination syscall.RawConn, readCounters []
 	}
 	defer unix.Close(pipeFDs[0])
 	defer unix.Close(pipeFDs[1])
-
 	_, _ = unix.FcntlInt(uintptr(pipeFDs[0]), unix.F_SETPIPE_SZ, maxSpliceSize)
-	var readN int
-	var readErr error
-	var writeSize int
-	var writeErr error
+	var (
+		readN        int
+		readErr      error
+		writeSize    int
+		writeErr     error
+		notFirstTime bool
+	)
 	readFunc := func(fd uintptr) (done bool) {
 		p0, p1 := unix.Splice(int(fd), nil, pipeFDs[1], nil, maxSpliceSize, unix.SPLICE_F_NONBLOCK)
 		readN = int(p0)
@@ -46,34 +48,49 @@ func splice(source syscall.RawConn, destination syscall.RawConn, readCounters []
 	}
 	for {
 		err = source.Read(readFunc)
-		if err != nil {
-			readErr = err
-		}
 		if readErr != nil {
-			if readErr == unix.EINVAL || readErr == unix.ENOSYS {
+			err = readErr
+		}
+		if err != nil {
+			if sourceReader != nil {
+				newBuffer, newErr := sourceReader.HandleSyscallReadError(err)
+				if newErr != nil {
+					err = newErr
+				} else {
+					err = nil
+					if len(newBuffer) > 0 {
+						readN, readErr = unix.Write(pipeFDs[1], newBuffer)
+						if readErr != nil {
+							err = E.Cause(err, "write handled data")
+						}
+					}
+				}
+			} else if !notFirstTime && E.IsMulti(err, unix.EINVAL, unix.ENOSYS) {
 				handed = false
 				return
 			}
-			err = E.Cause(readErr, "splice read")
+			err = E.Cause(err, "splice read")
 			return
 		}
 		if readN == 0 {
 			return
 		}
 		writeSize = readN
 		err = destination.Write(writeFunc)
-		if err != nil {
-			writeErr = err
-		}
 		if writeErr != nil {
-			err = E.Cause(writeErr, "splice write")
+			err = writeErr
+		}
+		if err != nil {
+			err = E.Cause(err, "splice write")
 			return
 		}
+		n += int64(readN)
 		for _, readCounter := range readCounters {
 			readCounter(int64(readN))
 		}
 		for _, writeCounter := range writeCounters {
 			writeCounter(int64(readN))
 		}
+		notFirstTime = true
 	}
 }

common/bufio/splice_stub.go

@@ -8,6 +8,6 @@ import (
 	N "github.com/sagernet/sing/common/network"
 )
 
-func splice(source syscall.RawConn, destination syscall.RawConn, readCounters []N.CountFunc, writeCounters []N.CountFunc) (handed bool, n int64, err error) {
+func splice(source syscall.RawConn, sourceReader N.SyscallReader, destination syscall.RawConn, destinationWriter N.SyscallWriter, readCounters []N.CountFunc, writeCounters []N.CountFunc) (handed bool, n int64, err error) {
 	return
 }

common/bufio/wait.go

@@ -3,11 +3,11 @@ package bufio
 import (
 	"io"
 
+	"github.com/sagernet/sing/common"
 	N "github.com/sagernet/sing/common/network"
 )
 
 func CreateReadWaiter(reader io.Reader) (N.ReadWaiter, bool) {
-	reader = N.UnwrapReader(reader)
 	if readWaiter, isReadWaiter := reader.(N.ReadWaiter); isReadWaiter {
 		return readWaiter, true
 	}
@@ -17,11 +17,19 @@ func CreateReadWaiter(reader io.Reader) (N.ReadWaiter, bool) {
 	if readWaiter, created := createSyscallReadWaiter(reader); created {
 		return readWaiter, true
 	}
+	if u, ok := reader.(N.ReaderWithUpstream); !ok || !u.ReaderReplaceable() {
+		return nil, false
+	}
+	if u, ok := reader.(N.WithUpstreamReader); ok {
+		return CreateReadWaiter(u.UpstreamReader().(io.Reader))
+	}
+	if u, ok := reader.(common.WithUpstream); ok {
+		return CreateReadWaiter(u.Upstream().(io.Reader))
+	}
 	return nil, false
 }
 
 func CreateVectorisedReadWaiter(reader io.Reader) (N.VectorisedReadWaiter, bool) {
-	reader = N.UnwrapReader(reader)
 	if vectorisedReadWaiter, isVectorised := reader.(N.VectorisedReadWaiter); isVectorised {
 		return vectorisedReadWaiter, true
 	}
@@ -31,11 +39,19 @@ func CreateVectorisedReadWaiter(reader io.Reader) (N.VectorisedReadWaiter, bool)
 	if vectorisedReadWaiter, created := createVectorisedSyscallReadWaiter(reader); created {
 		return vectorisedReadWaiter, true
 	}
+	if u, ok := reader.(N.ReaderWithUpstream); !ok || !u.ReaderReplaceable() {
+		return nil, false
+	}
+	if u, ok := reader.(N.WithUpstreamReader); ok {
+		return CreateVectorisedReadWaiter(u.UpstreamReader().(io.Reader))
+	}
+	if u, ok := reader.(common.WithUpstream); ok {
+		return CreateVectorisedReadWaiter(u.Upstream().(io.Reader))
+	}
 	return nil, false
 }
 
 func CreatePacketReadWaiter(reader N.PacketReader) (N.PacketReadWaiter, bool) {
-	reader = N.UnwrapPacketReader(reader)
 	if readWaiter, isReadWaiter := reader.(N.PacketReadWaiter); isReadWaiter {
 		return readWaiter, true
 	}
@@ -45,6 +61,15 @@ func CreatePacketReadWaiter(reader N.PacketReader) (N.PacketReadWaiter, bool) {
 	if readWaiter, created := createSyscallPacketReadWaiter(reader); created {
 		return readWaiter, true
 	}
+	if u, ok := reader.(N.ReaderWithUpstream); !ok || !u.ReaderReplaceable() {
+		return nil, false
+	}
+	if u, ok := reader.(N.WithUpstreamReader); ok {
+		return CreatePacketReadWaiter(u.UpstreamReader().(N.PacketReader))
+	}
+	if u, ok := reader.(common.WithUpstream); ok {
+		return CreatePacketReadWaiter(u.Upstream().(N.PacketReader))
+	}
 	return nil, false
 }
 

common/metadata/domain.go

@@ -1,6 +1,70 @@
 package metadata
 
-import _ "unsafe" // for linkname
+// IsDomainName checks if a string is a presentation-format domain name
+// (currently restricted to hostname-compatible "preferred name" LDH labels and
+// SRV-like "underscore labels"; see golang.org/issue/12421).
+//
+// This function was originally created here:
+//
+//	https://cs.opensource.google/go/go/+/master:src/net/dnsclient.go;l=76-146;drc=05cbbf985fed823a174bf95cc78a7d44f948fdab
+//
+// and it's being copy-pasted in order to use the same functionality. In the original package,
+// this is a private function that cannot be accessed externally
+func IsDomainName(s string) bool {
+	// The root domain name is valid. See golang.org/issue/45715.
+	if s == "." {
+		return true
+	}
 
-//go:linkname IsDomainName net.isDomainName
-func IsDomainName(domain string) bool
+	// See RFC 1035, RFC 3696.
+	// Presentation format has dots before every label except the first, and the
+	// terminal empty label is optional here because we assume fully-qualified
+	// (absolute) input. We must therefore reserve space for the first and last
+	// labels' length octets in wire format, where they are necessary and the
+	// maximum total length is 255.
+	// So our _effective_ maximum is 253, but 254 is not rejected if the last
+	// character is a dot.
+	l := len(s)
+	if l == 0 || l > 254 || l == 254 && s[l-1] != '.' {
+		return false
+	}
+
+	last := byte('.')
+	nonNumeric := false // true once we've seen a letter or hyphen
+	partlen := 0
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch {
+		default:
+			return false
+		case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || c == '_':
+			nonNumeric = true
+			partlen++
+		case '0' <= c && c <= '9':
+			// fine
+			partlen++
+		case c == '-':
+			// Byte before dash cannot be dot.
+			if last == '.' {
+				return false
+			}
+			partlen++
+			nonNumeric = true
+		case c == '.':
+			// Byte before dot cannot be dot, dash.
+			if last == '.' || last == '-' {
+				return false
+			}
+			if partlen > 63 || partlen == 0 {
+				return false
+			}
+			partlen = 0
+		}
+		last = c
+	}
+	if last == '-' || partlen > 63 {
+		return false
+	}
+
+	return nonNumeric
+}

common/network/counter.go

@@ -2,6 +2,9 @@ package network
 
 import (
 	"io"
+	"syscall"
+
+	"github.com/sagernet/sing/common"
 )
 
 type CountFunc func(n int64)
@@ -27,32 +30,65 @@ type PacketWriteCounter interface {
 }
 
 func UnwrapCountReader(reader io.Reader, countFunc []CountFunc) (io.Reader, []CountFunc) {
-	reader = UnwrapReader(reader)
 	if counter, isCounter := reader.(ReadCounter); isCounter {
 		upstreamReader, upstreamCountFunc := counter.UnwrapReader()
 		countFunc = append(countFunc, upstreamCountFunc...)
 		return UnwrapCountReader(upstreamReader, countFunc)
 	}
+	if u, ok := reader.(ReaderWithUpstream); !ok || !u.ReaderReplaceable() {
+		return reader, countFunc
+	}
+	switch u := reader.(type) {
+	case ReadWaiter, ReadWaitCreator, syscall.Conn, SyscallReader:
+		// In our use cases, counters is always at the top, so we stop when we encounter ReadWaiter
+		return reader, countFunc
+	case WithUpstreamReader:
+		return UnwrapCountReader(u.UpstreamReader().(io.Reader), countFunc)
+	case common.WithUpstream:
+		return UnwrapCountReader(u.Upstream().(io.Reader), countFunc)
+	}
 	return reader, countFunc
 }
 
 func UnwrapCountWriter(writer io.Writer, countFunc []CountFunc) (io.Writer, []CountFunc) {
-	writer = UnwrapWriter(writer)
 	if counter, isCounter := writer.(WriteCounter); isCounter {
 		upstreamWriter, upstreamCountFunc := counter.UnwrapWriter()
 		countFunc = append(countFunc, upstreamCountFunc...)
 		return UnwrapCountWriter(upstreamWriter, countFunc)
 	}
+	if u, ok := writer.(WriterWithUpstream); !ok || !u.WriterReplaceable() {
+		return writer, countFunc
+	}
+	switch u := writer.(type) {
+	case syscall.Conn, SyscallWriter:
+		// In our use cases, counters is always at the top, so we stop when we encounter syscall conn
+		return writer, countFunc
+	case WithUpstreamWriter:
+		return UnwrapCountWriter(u.UpstreamWriter().(io.Writer), countFunc)
+	case common.WithUpstream:
+		return UnwrapCountWriter(u.Upstream().(io.Writer), countFunc)
+	}
 	return writer, countFunc
 }
 
 func UnwrapCountPacketReader(reader PacketReader, countFunc []CountFunc) (PacketReader, []CountFunc) {
-	reader = UnwrapPacketReader(reader)
 	if counter, isCounter := reader.(PacketReadCounter); isCounter {
 		upstreamReader, upstreamCountFunc := counter.UnwrapPacketReader()
 		countFunc = append(countFunc, upstreamCountFunc...)
 		return UnwrapCountPacketReader(upstreamReader, countFunc)
 	}
+	if u, ok := reader.(ReaderWithUpstream); !ok || !u.ReaderReplaceable() {
+		return reader, countFunc
+	}
+	switch u := reader.(type) {
+	case PacketReadWaiter, PacketReadWaitCreator, syscall.Conn:
+		// In our use cases, counters is always at the top, so we stop when we encounter ReadWaiter
+		return reader, countFunc
+	case WithUpstreamReader:
+		return UnwrapCountPacketReader(u.UpstreamReader().(PacketReader), countFunc)
+	case common.WithUpstream:
+		return UnwrapCountPacketReader(u.Upstream().(PacketReader), countFunc)
+	}
 	return reader, countFunc
 }
 
@@ -63,5 +99,17 @@ func UnwrapCountPacketWriter(writer PacketWriter, countFunc []CountFunc) (Packet
 		countFunc = append(countFunc, upstreamCountFunc...)
 		return UnwrapCountPacketWriter(upstreamWriter, countFunc)
 	}
+	if u, ok := writer.(WriterWithUpstream); !ok || !u.WriterReplaceable() {
+		return writer, countFunc
+	}
+	switch u := writer.(type) {
+	case syscall.Conn:
+		// In our use cases, counters is always at the top, so we stop when we encounter syscall conn
+		return writer, countFunc
+	case WithUpstreamWriter:
+		return UnwrapCountPacketWriter(u.UpstreamWriter().(PacketWriter), countFunc)
+	case common.WithUpstream:
+		return UnwrapCountPacketWriter(u.Upstream().(PacketWriter), countFunc)
+	}
 	return writer, countFunc
 }