86 lines
2.4 KiB
Go
86 lines
2.4 KiB
Go
package routing
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import (
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"errors"
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"fmt"
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"net"
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)
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const (
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table = 200
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priority = 100
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)
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var (
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ErrDefaultIP = errors.New("cannot get default IP address")
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ErrDefaultRoute = errors.New("cannot get default route")
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ErrIPRuleAdd = errors.New("cannot add IP rule")
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ErrIPRuleDelete = errors.New("cannot delete IP rule")
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ErrRouteAdd = errors.New("cannot add route")
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ErrSubnetsOutboundSet = errors.New("cannot set outbound subnets routes")
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)
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func (r *routing) Setup() (err error) {
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defaultIP, err := r.DefaultIP()
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if err != nil {
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return fmt.Errorf("%w: %s", ErrDefaultIP, err)
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}
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defaultInterfaceName, defaultGateway, err := r.DefaultRoute()
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if err != nil {
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return fmt.Errorf("%w: %s", ErrDefaultRoute, err)
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}
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touched := false
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defer func() {
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if err != nil && touched {
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if tearDownErr := r.TearDown(); tearDownErr != nil {
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r.logger.Error("cannot reverse routing changes: " + tearDownErr.Error())
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}
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}
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}()
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if err := r.addIPRule(defaultIP, table, priority); err != nil {
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return fmt.Errorf("%w: %s", ErrIPRuleAdd, err)
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}
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touched = true
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defaultDestination := net.IPNet{IP: net.IPv4(0, 0, 0, 0), Mask: net.IPv4Mask(0, 0, 0, 0)}
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if err := r.addRouteVia(defaultDestination, defaultGateway, defaultInterfaceName, table); err != nil {
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return fmt.Errorf("%w: %s", ErrRouteAdd, err)
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}
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r.stateMutex.RLock()
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outboundSubnets := r.outboundSubnets
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r.stateMutex.RUnlock()
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if err := r.setOutboundRoutes(outboundSubnets, defaultInterfaceName, defaultGateway); err != nil {
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return fmt.Errorf("%w: %s", ErrSubnetsOutboundSet, err)
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}
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return nil
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}
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func (r *routing) TearDown() error {
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defaultIP, err := r.DefaultIP()
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if err != nil {
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return fmt.Errorf("%w: %s", ErrDefaultIP, err)
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}
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defaultInterfaceName, defaultGateway, err := r.DefaultRoute()
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if err != nil {
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return fmt.Errorf("%w: %s", ErrDefaultRoute, err)
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}
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defaultNet := net.IPNet{IP: net.IPv4(0, 0, 0, 0), Mask: net.IPv4Mask(0, 0, 0, 0)}
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if err := r.deleteRouteVia(defaultNet, defaultGateway, defaultInterfaceName, table); err != nil {
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return fmt.Errorf("%w: %s", ErrRouteDelete, err)
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}
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if err := r.deleteIPRule(defaultIP, table, priority); err != nil {
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return fmt.Errorf("%w: %s", ErrIPRuleDelete, err)
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}
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if err := r.setOutboundRoutes(nil, defaultInterfaceName, defaultGateway); err != nil {
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return fmt.Errorf("%w: %s", ErrSubnetsOutboundSet, err)
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}
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return nil
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}
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