forked from TrueCloudLab/distribution
a685e3fc98
Vndr has a simpler configuration and allows pointing to forked packages. Additionally other docker projects are now using vndr making vendoring in distribution more consistent. Updates letsencrypt to use fork. No longer uses sub-vendored packages. Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
73 lines
2.1 KiB
Go
73 lines
2.1 KiB
Go
// +build linux
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package dns
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// See:
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// * http://stackoverflow.com/questions/3062205/setting-the-source-ip-for-a-udp-socket and
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// * http://blog.powerdns.com/2012/10/08/on-binding-datagram-udp-sockets-to-the-any-addresses/
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//
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// Why do we need this: When listening on 0.0.0.0 with UDP so kernel decides what is the outgoing
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// interface, this might not always be the correct one. This code will make sure the egress
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// packet's interface matched the ingress' one.
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import (
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"net"
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"syscall"
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)
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// setUDPSocketOptions4 prepares the v4 socket for sessions.
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func setUDPSocketOptions4(conn *net.UDPConn) error {
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file, err := conn.File()
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if err != nil {
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return err
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}
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if err := syscall.SetsockoptInt(int(file.Fd()), syscall.IPPROTO_IP, syscall.IP_PKTINFO, 1); err != nil {
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return err
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}
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// Calling File() above results in the connection becoming blocking, we must fix that.
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// See https://github.com/miekg/dns/issues/279
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err = syscall.SetNonblock(int(file.Fd()), true)
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if err != nil {
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return err
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}
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return nil
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}
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// setUDPSocketOptions6 prepares the v6 socket for sessions.
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func setUDPSocketOptions6(conn *net.UDPConn) error {
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file, err := conn.File()
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if err != nil {
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return err
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}
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if err := syscall.SetsockoptInt(int(file.Fd()), syscall.IPPROTO_IPV6, syscall.IPV6_RECVPKTINFO, 1); err != nil {
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return err
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}
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err = syscall.SetNonblock(int(file.Fd()), true)
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if err != nil {
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return err
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}
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return nil
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}
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// getUDPSocketOption6Only return true if the socket is v6 only and false when it is v4/v6 combined
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// (dualstack).
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func getUDPSocketOptions6Only(conn *net.UDPConn) (bool, error) {
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file, err := conn.File()
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if err != nil {
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return false, err
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}
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// dual stack. See http://stackoverflow.com/questions/1618240/how-to-support-both-ipv4-and-ipv6-connections
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v6only, err := syscall.GetsockoptInt(int(file.Fd()), syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY)
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if err != nil {
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return false, err
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}
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return v6only == 1, nil
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}
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func getUDPSocketName(conn *net.UDPConn) (syscall.Sockaddr, error) {
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file, err := conn.File()
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if err != nil {
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return nil, err
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}
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return syscall.Getsockname(int(file.Fd()))
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}
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