Simon LawandSimon Law
cb7e536804
Previously, refreshing the routecheck.Client would probe to generate a new routecheck.Report, but this method was only wired up to the LocalAPI and the `tailscale routecheck` command. However, waiting for a probe to finish before choosing a router would take too long, so we must keep a regularly updated report to be consulted as necessary. This patch adds a Start and Close method to the routecheck.Client and starts it in the background from features/routecheck. To enable this feature for a given node, set both of the following node attributes: `client-side-reachability` and `client-side-reachability-routecheck`. This patch also wires up the RouterTracker.OnRoutersChange hook, which fires a callback whenever a new network map includes information about a router node, This signals to the routecheck.Client that it might need to schedule another probe, if the shape of the routing table has changed materially. Updates #17366 Updates tailscale/corp#33033 Signed-off-by: Simon Law <sfllaw@tailscale.com>
57 lines
2.0 KiB
Go
57 lines
2.0 KiB
Go
// Copyright (c) Tailscale Inc & contributors
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// SPDX-License-Identifier: BSD-3-Clause
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package routecheck
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import (
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"net/netip"
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"tailscale.com/tailcfg"
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"tailscale.com/types/views"
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"tailscale.com/util/mak"
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)
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// RoutersByPrefix represents a map of nodes grouped by the subnet that they route.
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// Nodes that route for /0 prefixes are exit nodes, their subnet is the Internet.
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// The result omits any prefix that is one of a node’s local addresses.
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//
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// Note: Fallback routes are not supported by design. If a subnet prefix
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// contained within another more general prefix has no reachable routers,
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// traffic is still sent to one of those unreachable routers.
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// Routers for the general prefix aren’t candidates. See tailscale/tailscale#18550.
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type RoutersByPrefix map[netip.Prefix][]tailcfg.NodeView
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// RoutersByPrefix returns a map of nodes grouped by the subnet that they route.
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// See [RoutersByPrefix] for more detail.
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func (c *Client) RoutersByPrefix() RoutersByPrefix {
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return GroupRoutersByPrefix(c.nb.NodeBackend().Peers())
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}
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// GroupRoutersByPrefix returns a map of nodes grouped by the subnet that they route.
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// See [RoutersByPrefix] for more detail.
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func GroupRoutersByPrefix(nodes []tailcfg.NodeView) RoutersByPrefix {
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var routers RoutersByPrefix
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for _, n := range nodes {
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for _, pfx := range routes(n) {
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mak.Set(&routers, pfx, append(routers[pfx], n))
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}
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}
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return routers
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}
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// Routes returns a slice of subnets that the given node will route.
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// If the node is an exit node, the result will contain at least one /0 prefix.
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// If the node is a subnet router, the result will contain a smaller prefix.
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// The result omits any prefix that is one of the node’s local addresses.
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func routes(n tailcfg.NodeView) []netip.Prefix {
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var routes []netip.Prefix
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for _, pfx := range n.AllowedIPs().All() {
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// Routers never forward their own local addresses.
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if views.SliceContains(n.Addresses(), pfx) {
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continue
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}
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routes = append(routes, pfx)
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}
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return routes
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}
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