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tailscale/tailcfg/derpmap.go

126 lines
4.4 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tailcfg
import "sort"
// DERPMap describes the set of DERP packet relay servers that are available.
type DERPMap struct {
// 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
}
/// 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
}
// 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.
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
// 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"`
// CertFingerprint, if non-empty, specifies the expected
// lowercase hex of the SHA-256 of the TLS server's offered
// certificate. If empty, the system default RootCAs are used.
CertFingerprint []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"`
// DERPTestPort is used in tests to override the port, instead
// of using the default port of 443. If non-zero, TLS
// verification is skipped.
DERPTestPort int `json:",omitempty"`
}