mirror of
https://source.quilibrium.com/quilibrium/ceremonyclient.git
synced 2024-12-26 16:45:18 +00:00
115 lines
3.4 KiB
Go
115 lines
3.4 KiB
Go
package reuseport
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import (
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"context"
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"fmt"
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"math/rand"
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"net"
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"github.com/libp2p/go-netroute"
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)
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type dialer struct {
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// All address that are _not_ loopback or unspecified (0.0.0.0 or ::).
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specific []*net.TCPAddr
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// All loopback addresses (127.*.*.*, ::1).
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loopback []*net.TCPAddr
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// Unspecified addresses (0.0.0.0, ::)
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unspecified []*net.TCPAddr
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}
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func (d *dialer) Dial(network, addr string) (net.Conn, error) {
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return d.DialContext(context.Background(), network, addr)
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}
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func randAddr(addrs []*net.TCPAddr) *net.TCPAddr {
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if len(addrs) > 0 {
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return addrs[rand.Intn(len(addrs))]
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}
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return nil
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}
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// DialContext dials a target addr.
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//
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// In-order:
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//
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// 1. If we're _explicitly_ listening on the preferred source address for the destination address
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// (per the system's routes), we'll use that listener's port as the source port.
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// 2. If we're listening on one or more _unspecified_ addresses (zero address), we'll pick a source
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// port from one of these listener's.
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// 3. Otherwise, we'll let the system pick the source port.
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func (d *dialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
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// We only check this case if the user is listening on a specific address (loopback or
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// otherwise). Generally, users will listen on the "unspecified" address (0.0.0.0 or ::) and
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// we can skip this section.
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//
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// This lets us avoid resolving the address twice, in most cases.
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if len(d.specific) > 0 || len(d.loopback) > 0 {
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tcpAddr, err := net.ResolveTCPAddr(network, addr)
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if err != nil {
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return nil, err
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}
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ip := tcpAddr.IP
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if !ip.IsLoopback() && !ip.IsGlobalUnicast() {
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return nil, fmt.Errorf("undialable IP: %s", ip)
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}
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// If we're listening on some specific address and that specific address happens to
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// be the preferred source address for the target destination address, we try to
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// dial with that address/port.
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//
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// We skip this check if we _aren't_ listening on any specific addresses, because
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// checking routing tables can be expensive and users rarely listen on specific IP
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// addresses.
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if len(d.specific) > 0 {
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if router, err := netroute.New(); err == nil {
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if _, _, preferredSrc, err := router.Route(ip); err == nil {
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for _, optAddr := range d.specific {
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if optAddr.IP.Equal(preferredSrc) {
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return reuseDial(ctx, optAddr, network, addr)
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}
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}
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}
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}
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}
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// Otherwise, if we are listening on a loopback address and the destination is also
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// a loopback address, use the port from our loopback listener.
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if len(d.loopback) > 0 && ip.IsLoopback() {
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return reuseDial(ctx, randAddr(d.loopback), network, addr)
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}
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}
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// If we're listening on any uspecified addresses, use a randomly chosen port from one of
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// these listeners.
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if len(d.unspecified) > 0 {
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return reuseDial(ctx, randAddr(d.unspecified), network, addr)
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}
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// Finally, just pick a random port.
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var dialer net.Dialer
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return dialer.DialContext(ctx, network, addr)
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}
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func newDialer(listeners map[*listener]struct{}) *dialer {
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specific := make([]*net.TCPAddr, 0)
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loopback := make([]*net.TCPAddr, 0)
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unspecified := make([]*net.TCPAddr, 0)
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for l := range listeners {
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addr := l.Addr().(*net.TCPAddr)
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if addr.IP.IsLoopback() {
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loopback = append(loopback, addr)
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} else if addr.IP.IsUnspecified() {
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unspecified = append(unspecified, addr)
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} else {
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specific = append(specific, addr)
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}
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}
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return &dialer{
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specific: specific,
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loopback: loopback,
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unspecified: unspecified,
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}
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}
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