ginuerzh
caa82f2861
When using IP aliases on loopback (e.g. ip addr add 10.1.1.1/32 dev lo) with policy routing, findInterfaceByIP() resolves the alias IP to the loopback interface. Binding the socket to lo via SO_BINDTODEVICE prevents outbound traffic from reaching non-local destinations. Skip SO_BINDTODEVICE when the resolved interface is loopback — source IP binding via LocalAddr is sufficient for policy routing to steer traffic through the correct physical interface.
36 lines
883 B
Go
36 lines
883 B
Go
package dialer
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import (
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"net"
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"golang.org/x/sys/unix"
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)
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func bindDevice(network, address string, fd uintptr, ifceName string) error {
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if ifceName == "" {
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return nil
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}
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// Skip SO_BINDTODEVICE for loopback interface — it prevents
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// outbound traffic from reaching non-local destinations.
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// Source IP binding via LocalAddr is sufficient for policy routing
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// when using IP aliases on loopback (e.g. ip addr add 10.1.1.1/32 dev lo).
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if ifce, err := net.InterfaceByName(ifceName); err == nil && ifce.Flags&net.FlagLoopback != 0 {
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return nil
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}
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host, _, _ := net.SplitHostPort(address)
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if ip := net.ParseIP(host); ip != nil && !ip.IsGlobalUnicast() {
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return nil
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}
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return unix.BindToDevice(int(fd), ifceName)
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}
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func setMark(fd uintptr, mark int) error {
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if mark == 0 {
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return nil
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}
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return unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, mark)
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}
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