tailscale/tailcfg/derpmap.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package tailcfg
import (
"net/netip"
"sort"
"tailscale.com/types/key"
)
// DERPMap describes the set of DERP packet relay servers that are available.
type DERPMap struct {
// HomeParams, if non-nil, is a change in home parameters.
//
// The rest of the DEPRMap fields, if zero, means unchanged.
HomeParams *DERPHomeParams `json:",omitempty"`
// Regions is the set of geographic regions running DERP node(s).
//
// It's keyed by the DERPRegion.RegionID.
//
// The numbers are not necessarily contiguous.
Regions map[int]*DERPRegion
// OmitDefaultRegions specifies to not use Tailscale's DERP servers, and only use those
// specified in this DERPMap. If there are none set outside of the defaults, this is a noop.
//
// This field is only meaningful if the Regions map is non-nil (indicating a change).
OmitDefaultRegions bool `json:"omitDefaultRegions,omitempty"`
}
// / RegionIDs returns the sorted region IDs.
func (m *DERPMap) RegionIDs() []int {
ret := make([]int, 0, len(m.Regions))
for rid := range m.Regions {
ret = append(ret, rid)
}
sort.Ints(ret)
return ret
}
// DERPHomeParams contains parameters from the server related to selecting a
// DERP home region (sometimes referred to as the "preferred DERP").
type DERPHomeParams struct {
// RegionScore scales latencies of DERP regions by a given scaling
// factor when determining which region to use as the home
// ("preferred") DERP. Scores in the range (0, 1) will cause this
// region to be proportionally more preferred, and scores in the range
// (1, ∞) will penalize a region.
//
// If a region is not present in this map, it is treated as having a
// score of 1.0.
//
// Scores should not be 0 or negative; such scores will be ignored.
//
// A nil map means no change from the previous value (if any); an empty
// non-nil map can be sent to reset all scores back to 1.0.
RegionScore map[int]float64 `json:",omitempty"`
}
// DERPRegion is a geographic region running DERP relay node(s).
//
// Client nodes discover which region they're closest to, advertise
// that "home" DERP region (previously called "home node", when there
// was only 1 node per region) and maintain a persistent connection
// that region as long as it's the closest. Client nodes will further
// connect to other regions as necessary to communicate with peers
// advertising other regions as their homes.
type DERPRegion struct {
// RegionID is a unique integer for a geographic region.
//
// It corresponds to the legacy derpN.tailscale.com hostnames
// used by older clients. (Older clients will continue to resolve
// derpN.tailscale.com when contacting peers, rather than use
// the server-provided DERPMap)
//
// RegionIDs must be non-zero, positive, and guaranteed to fit
// in a JavaScript number.
//
// RegionIDs in range 900-999 are reserved for end users to run their
// own DERP nodes.
RegionID int
// RegionCode is a short name for the region. It's usually a popular
// city or airport code in the region: "nyc", "sf", "sin",
// "fra", etc.
RegionCode string
// RegionName is a long English name for the region: "New York City",
// "San Francisco", "Singapore", "Frankfurt", etc.
RegionName string
// Latitude, Longitude are optional geographical coordinates of the DERP region's city, in degrees.
Latitude float64 `json:",omitempty"`
Longitude float64 `json:",omitempty"`
// Avoid is whether the client should avoid picking this as its home
// region. The region should only be used if a peer is there.
// Clients already using this region as their home should migrate
// away to a new region without Avoid set.
Avoid bool `json:",omitempty"`
// Nodes are the DERP nodes running in this region, in
// priority order for the current client. Client TLS
// connections should ideally only go to the first entry
// (falling back to the second if necessary). STUN packets
// should go to the first 1 or 2.
//
// If nodes within a region route packets amongst themselves,
// but not to other regions. That said, each user/domain
// should get a the same preferred node order, so if all nodes
// for a user/network pick the first one (as they should, when
// things are healthy), the inter-cluster routing is minimal
// to zero.
Nodes []*DERPNode
}
// DERPNode describes a DERP packet relay node running within a DERPRegion.
type DERPNode struct {
// Name is a unique node name (across all regions).
// It is not a host name.
// It's typically of the form "1b", "2a", "3b", etc. (region
// ID + suffix within that region)
Name string
// RegionID is the RegionID of the DERPRegion that this node
// is running in.
RegionID int
// HostName is the DERP node's hostname.
//
// It is required but need not be unique; multiple nodes may
// have the same HostName but vary in configuration otherwise.
HostName string
// CertName optionally specifies the expected TLS cert common
// name. If empty, HostName is used. If CertName is non-empty,
// HostName is only used for the TCP dial (if IPv4/IPv6 are
// not present) + TLS ClientHello.
CertName string `json:",omitempty"`
// IPv4 optionally forces an IPv4 address to use, instead of using DNS.
// If empty, A record(s) from DNS lookups of HostName are used.
// If the string is not an IPv4 address, IPv4 is not used; the
// conventional string to disable IPv4 (and not use DNS) is
// "none".
IPv4 string `json:",omitempty"`
// IPv6 optionally forces an IPv6 address to use, instead of using DNS.
// If empty, AAAA record(s) from DNS lookups of HostName are used.
// If the string is not an IPv6 address, IPv6 is not used; the
// conventional string to disable IPv6 (and not use DNS) is
// "none".
IPv6 string `json:",omitempty"`
// Port optionally specifies a STUN port to use.
// Zero means 3478.
// To disable STUN on this node, use -1.
STUNPort int `json:",omitempty"`
// STUNOnly marks a node as only a STUN server and not a DERP
// server.
STUNOnly bool `json:",omitempty"`
// DERPPort optionally provides an alternate TLS port number
// for the DERP HTTPS server.
//
// If zero, 443 is used.
DERPPort int `json:",omitempty"`
// InsecureForTests is used by unit tests to disable TLS verification.
// It should not be set by users.
InsecureForTests bool `json:",omitempty"`
// STUNTestIP is used in tests to override the STUN server's IP.
// If empty, it's assumed to be the same as the DERP server.
STUNTestIP string `json:",omitempty"`
// CanPort80 specifies whether this DERP node is accessible over HTTP
// on port 80 specifically. This is used for captive portal checks.
CanPort80 bool `json:",omitempty"`
}
func (n *DERPNode) IsTestNode() bool {
return n.STUNTestIP != "" || n.IPv4 == "127.0.0.1"
}
// DotInvalid is a fake DNS TLD used in tests for an invalid hostname.
const DotInvalid = ".invalid"
// DERPAdmitClientRequest is the JSON request body of a POST to derper's
// --verify-client-url admission controller URL.
type DERPAdmitClientRequest struct {
NodePublic key.NodePublic // key to query for admission
Source netip.Addr // derp client's IP address
}
// DERPAdmitClientResponse is the response to a DERPAdmitClientRequest.
type DERPAdmitClientResponse struct {
Allow bool // whether to permit client
// TODO(bradfitz,maisem): bandwidth limits, etc?
}