clone from danieldin95

vendor/github.com/xtaci/kcp-go/v5/tx_linux.go

@@ -0,0 +1,51 @@
+// +build linux
+
+package kcp
+
+import (
+	"net"
+	"os"
+	"sync/atomic"
+
+	"github.com/pkg/errors"
+	"golang.org/x/net/ipv4"
+)
+
+func (s *UDPSession) tx(txqueue []ipv4.Message) {
+	// default version
+	if s.xconn == nil || s.xconnWriteError != nil {
+		s.defaultTx(txqueue)
+		return
+	}
+
+	// x/net version
+	nbytes := 0
+	npkts := 0
+	for len(txqueue) > 0 {
+		if n, err := s.xconn.WriteBatch(txqueue, 0); err == nil {
+			for k := range txqueue[:n] {
+				nbytes += len(txqueue[k].Buffers[0])
+			}
+			npkts += n
+			txqueue = txqueue[n:]
+		} else {
+			// compatibility issue:
+			// for linux kernel<=2.6.32, support for sendmmsg is not available
+			// an error of type os.SyscallError will be returned
+			if operr, ok := err.(*net.OpError); ok {
+				if se, ok := operr.Err.(*os.SyscallError); ok {
+					if se.Syscall == "sendmmsg" {
+						s.xconnWriteError = se
+						s.defaultTx(txqueue)
+						return
+					}
+				}
+			}
+			s.notifyWriteError(errors.WithStack(err))
+			break
+		}
+	}
+
+	atomic.AddUint64(&DefaultSnmp.OutPkts, uint64(npkts))
+	atomic.AddUint64(&DefaultSnmp.OutBytes, uint64(nbytes))
+}