mirror of
https://github.com/juanfont/headscale.git
synced 2024-11-27 12:05:26 +00:00
move reminder of dns funcs to util
Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
This commit is contained in:
Kristoffer Dalby
Kristoffer Dalby
parent
d36336a572
commit
c1218ad3c2
@ -192,7 +192,7 @@ func NewHeadscale(cfg *types.Config) (*Headscale, error) {
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}
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if app.cfg.DNSConfig != nil && app.cfg.DNSConfig.Proxied { // if MagicDNS
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magicDNSDomains := generateMagicDNSRootDomains(app.cfg.IPPrefixes)
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magicDNSDomains := util.GenerateMagicDNSRootDomains(app.cfg.IPPrefixes)
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// we might have routes already from Split DNS
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if app.cfg.DNSConfig.Routes == nil {
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app.cfg.DNSConfig.Routes = make(map[string][]*dnstype.Resolver)
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151
hscontrol/dns.go
151
hscontrol/dns.go
@ -1,151 +0,0 @@
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package hscontrol
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import (
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"fmt"
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"net/netip"
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"strings"
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"go4.org/netipx"
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"tailscale.com/util/dnsname"
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)
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const (
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ByteSize = 8
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)
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const (
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ipv4AddressLength = 32
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ipv6AddressLength = 128
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)
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// generateMagicDNSRootDomains generates a list of DNS entries to be included in `Routes` in `MapResponse`.
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// This list of reverse DNS entries instructs the OS on what subnets and domains the Tailscale embedded DNS
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// server (listening in 100.100.100.100 udp/53) should be used for.
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//
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// Tailscale.com includes in the list:
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// - the `BaseDomain` of the user
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// - the reverse DNS entry for IPv6 (0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa., see below more on IPv6)
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// - the reverse DNS entries for the IPv4 subnets covered by the user's `IPPrefix`.
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// In the public SaaS this is [64-127].100.in-addr.arpa.
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//
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// The main purpose of this function is then generating the list of IPv4 entries. For the 100.64.0.0/10, this
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// is clear, and could be hardcoded. But we are allowing any range as `IPPrefix`, so we need to find out the
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// subnets when we have 172.16.0.0/16 (i.e., [0-255].16.172.in-addr.arpa.), or any other subnet.
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//
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// How IN-ADDR.ARPA domains work is defined in RFC1035 (section 3.5). Tailscale.com seems to adhere to this,
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// and do not make use of RFC2317 ("Classless IN-ADDR.ARPA delegation") - hence generating the entries for the next
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// class block only.
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// From the netmask we can find out the wildcard bits (the bits that are not set in the netmask).
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// This allows us to then calculate the subnets included in the subsequent class block and generate the entries.
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func generateMagicDNSRootDomains(ipPrefixes []netip.Prefix) []dnsname.FQDN {
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fqdns := make([]dnsname.FQDN, 0, len(ipPrefixes))
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for _, ipPrefix := range ipPrefixes {
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var generateDNSRoot func(netip.Prefix) []dnsname.FQDN
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switch ipPrefix.Addr().BitLen() {
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case ipv4AddressLength:
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generateDNSRoot = generateIPv4DNSRootDomain
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case ipv6AddressLength:
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generateDNSRoot = generateIPv6DNSRootDomain
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default:
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panic(
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fmt.Sprintf(
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"unsupported IP version with address length %d",
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ipPrefix.Addr().BitLen(),
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),
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)
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}
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fqdns = append(fqdns, generateDNSRoot(ipPrefix)...)
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}
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return fqdns
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}
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func generateIPv4DNSRootDomain(ipPrefix netip.Prefix) []dnsname.FQDN {
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// Conversion to the std lib net.IPnet, a bit easier to operate
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netRange := netipx.PrefixIPNet(ipPrefix)
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maskBits, _ := netRange.Mask.Size()
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// lastOctet is the last IP byte covered by the mask
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lastOctet := maskBits / ByteSize
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// wildcardBits is the number of bits not under the mask in the lastOctet
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wildcardBits := ByteSize - maskBits%ByteSize
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// min is the value in the lastOctet byte of the IP
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// max is basically 2^wildcardBits - i.e., the value when all the wildcardBits are set to 1
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min := uint(netRange.IP[lastOctet])
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max := (min + 1<<uint(wildcardBits)) - 1
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// here we generate the base domain (e.g., 100.in-addr.arpa., 16.172.in-addr.arpa., etc.)
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rdnsSlice := []string{}
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for i := lastOctet - 1; i >= 0; i-- {
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rdnsSlice = append(rdnsSlice, fmt.Sprintf("%d", netRange.IP[i]))
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}
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rdnsSlice = append(rdnsSlice, "in-addr.arpa.")
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rdnsBase := strings.Join(rdnsSlice, ".")
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fqdns := make([]dnsname.FQDN, 0, max-min+1)
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for i := min; i <= max; i++ {
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fqdn, err := dnsname.ToFQDN(fmt.Sprintf("%d.%s", i, rdnsBase))
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if err != nil {
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continue
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}
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fqdns = append(fqdns, fqdn)
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}
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return fqdns
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}
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func generateIPv6DNSRootDomain(ipPrefix netip.Prefix) []dnsname.FQDN {
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const nibbleLen = 4
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maskBits, _ := netipx.PrefixIPNet(ipPrefix).Mask.Size()
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expanded := ipPrefix.Addr().StringExpanded()
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nibbleStr := strings.Map(func(r rune) rune {
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if r == ':' {
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return -1
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}
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return r
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}, expanded)
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// TODO?: that does not look the most efficient implementation,
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// but the inputs are not so long as to cause problems,
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// and from what I can see, the generateMagicDNSRootDomains
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// function is called only once over the lifetime of a server process.
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prefixConstantParts := []string{}
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for i := 0; i < maskBits/nibbleLen; i++ {
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prefixConstantParts = append(
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[]string{string(nibbleStr[i])},
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prefixConstantParts...)
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}
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makeDomain := func(variablePrefix ...string) (dnsname.FQDN, error) {
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prefix := strings.Join(append(variablePrefix, prefixConstantParts...), ".")
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return dnsname.ToFQDN(fmt.Sprintf("%s.ip6.arpa", prefix))
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}
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var fqdns []dnsname.FQDN
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if maskBits%4 == 0 {
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dom, _ := makeDomain()
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fqdns = append(fqdns, dom)
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} else {
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domCount := 1 << (maskBits % nibbleLen)
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fqdns = make([]dnsname.FQDN, 0, domCount)
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for i := 0; i < domCount; i++ {
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varNibble := fmt.Sprintf("%x", i)
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dom, err := makeDomain(varNibble)
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if err != nil {
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continue
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}
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fqdns = append(fqdns, dom)
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}
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}
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return fqdns
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}
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@ -1,109 +0,0 @@
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package hscontrol
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import (
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"net/netip"
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"gopkg.in/check.v1"
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)
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func (s *Suite) TestMagicDNSRootDomains100(c *check.C) {
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prefixes := []netip.Prefix{
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netip.MustParsePrefix("100.64.0.0/10"),
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}
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domains := generateMagicDNSRootDomains(prefixes)
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found := false
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for _, domain := range domains {
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if domain == "64.100.in-addr.arpa." {
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found = true
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break
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}
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}
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c.Assert(found, check.Equals, true)
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found = false
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for _, domain := range domains {
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if domain == "100.100.in-addr.arpa." {
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found = true
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break
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}
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}
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c.Assert(found, check.Equals, true)
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found = false
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for _, domain := range domains {
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if domain == "127.100.in-addr.arpa." {
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found = true
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break
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}
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}
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c.Assert(found, check.Equals, true)
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}
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func (s *Suite) TestMagicDNSRootDomains172(c *check.C) {
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prefixes := []netip.Prefix{
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netip.MustParsePrefix("172.16.0.0/16"),
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}
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domains := generateMagicDNSRootDomains(prefixes)
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found := false
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for _, domain := range domains {
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if domain == "0.16.172.in-addr.arpa." {
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found = true
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break
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}
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}
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c.Assert(found, check.Equals, true)
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found = false
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for _, domain := range domains {
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if domain == "255.16.172.in-addr.arpa." {
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found = true
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break
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}
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}
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c.Assert(found, check.Equals, true)
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}
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// Happens when netmask is a multiple of 4 bits (sounds likely).
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func (s *Suite) TestMagicDNSRootDomainsIPv6Single(c *check.C) {
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prefixes := []netip.Prefix{
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netip.MustParsePrefix("fd7a:115c:a1e0::/48"),
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}
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domains := generateMagicDNSRootDomains(prefixes)
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c.Assert(len(domains), check.Equals, 1)
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c.Assert(
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domains[0].WithTrailingDot(),
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check.Equals,
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"0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa.",
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)
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}
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func (s *Suite) TestMagicDNSRootDomainsIPv6SingleMultiple(c *check.C) {
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prefixes := []netip.Prefix{
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netip.MustParsePrefix("fd7a:115c:a1e0::/50"),
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}
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domains := generateMagicDNSRootDomains(prefixes)
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yieldsRoot := func(dom string) bool {
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for _, candidate := range domains {
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if candidate.WithTrailingDot() == dom {
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return true
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}
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}
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return false
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}
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c.Assert(len(domains), check.Equals, 4)
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c.Assert(yieldsRoot("0.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."), check.Equals, true)
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c.Assert(yieldsRoot("1.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."), check.Equals, true)
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c.Assert(yieldsRoot("2.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."), check.Equals, true)
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c.Assert(yieldsRoot("3.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."), check.Equals, true)
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}
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@ -3,11 +3,19 @@ package util
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import (
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"errors"
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"fmt"
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"net/netip"
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"regexp"
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"strings"
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"go4.org/netipx"
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"tailscale.com/util/dnsname"
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)
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const (
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ByteSize = 8
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ipv4AddressLength = 32
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ipv6AddressLength = 128
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// value related to RFC 1123 and 952.
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LabelHostnameLength = 63
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)
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@ -67,3 +75,135 @@ func CheckForFQDNRules(name string) error {
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return nil
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}
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// generateMagicDNSRootDomains generates a list of DNS entries to be included in `Routes` in `MapResponse`.
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// This list of reverse DNS entries instructs the OS on what subnets and domains the Tailscale embedded DNS
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// server (listening in 100.100.100.100 udp/53) should be used for.
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//
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// Tailscale.com includes in the list:
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// - the `BaseDomain` of the user
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// - the reverse DNS entry for IPv6 (0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa., see below more on IPv6)
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// - the reverse DNS entries for the IPv4 subnets covered by the user's `IPPrefix`.
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// In the public SaaS this is [64-127].100.in-addr.arpa.
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//
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// The main purpose of this function is then generating the list of IPv4 entries. For the 100.64.0.0/10, this
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// is clear, and could be hardcoded. But we are allowing any range as `IPPrefix`, so we need to find out the
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// subnets when we have 172.16.0.0/16 (i.e., [0-255].16.172.in-addr.arpa.), or any other subnet.
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//
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// How IN-ADDR.ARPA domains work is defined in RFC1035 (section 3.5). Tailscale.com seems to adhere to this,
|
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// and do not make use of RFC2317 ("Classless IN-ADDR.ARPA delegation") - hence generating the entries for the next
|
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// class block only.
|
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|
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// From the netmask we can find out the wildcard bits (the bits that are not set in the netmask).
|
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// This allows us to then calculate the subnets included in the subsequent class block and generate the entries.
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func GenerateMagicDNSRootDomains(ipPrefixes []netip.Prefix) []dnsname.FQDN {
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fqdns := make([]dnsname.FQDN, 0, len(ipPrefixes))
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for _, ipPrefix := range ipPrefixes {
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var generateDNSRoot func(netip.Prefix) []dnsname.FQDN
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switch ipPrefix.Addr().BitLen() {
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case ipv4AddressLength:
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generateDNSRoot = generateIPv4DNSRootDomain
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case ipv6AddressLength:
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generateDNSRoot = generateIPv6DNSRootDomain
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default:
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panic(
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fmt.Sprintf(
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"unsupported IP version with address length %d",
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ipPrefix.Addr().BitLen(),
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),
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)
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}
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fqdns = append(fqdns, generateDNSRoot(ipPrefix)...)
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}
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return fqdns
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}
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func generateIPv4DNSRootDomain(ipPrefix netip.Prefix) []dnsname.FQDN {
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// Conversion to the std lib net.IPnet, a bit easier to operate
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netRange := netipx.PrefixIPNet(ipPrefix)
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maskBits, _ := netRange.Mask.Size()
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// lastOctet is the last IP byte covered by the mask
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lastOctet := maskBits / ByteSize
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// wildcardBits is the number of bits not under the mask in the lastOctet
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wildcardBits := ByteSize - maskBits%ByteSize
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// min is the value in the lastOctet byte of the IP
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// max is basically 2^wildcardBits - i.e., the value when all the wildcardBits are set to 1
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min := uint(netRange.IP[lastOctet])
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max := (min + 1<<uint(wildcardBits)) - 1
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// here we generate the base domain (e.g., 100.in-addr.arpa., 16.172.in-addr.arpa., etc.)
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rdnsSlice := []string{}
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for i := lastOctet - 1; i >= 0; i-- {
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rdnsSlice = append(rdnsSlice, fmt.Sprintf("%d", netRange.IP[i]))
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}
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rdnsSlice = append(rdnsSlice, "in-addr.arpa.")
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rdnsBase := strings.Join(rdnsSlice, ".")
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fqdns := make([]dnsname.FQDN, 0, max-min+1)
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for i := min; i <= max; i++ {
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fqdn, err := dnsname.ToFQDN(fmt.Sprintf("%d.%s", i, rdnsBase))
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if err != nil {
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continue
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}
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fqdns = append(fqdns, fqdn)
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}
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return fqdns
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}
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func generateIPv6DNSRootDomain(ipPrefix netip.Prefix) []dnsname.FQDN {
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const nibbleLen = 4
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maskBits, _ := netipx.PrefixIPNet(ipPrefix).Mask.Size()
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expanded := ipPrefix.Addr().StringExpanded()
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nibbleStr := strings.Map(func(r rune) rune {
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if r == ':' {
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return -1
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}
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return r
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}, expanded)
|
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|
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// TODO?: that does not look the most efficient implementation,
|
||||
// but the inputs are not so long as to cause problems,
|
||||
// and from what I can see, the generateMagicDNSRootDomains
|
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// function is called only once over the lifetime of a server process.
|
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prefixConstantParts := []string{}
|
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for i := 0; i < maskBits/nibbleLen; i++ {
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prefixConstantParts = append(
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[]string{string(nibbleStr[i])},
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prefixConstantParts...)
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}
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makeDomain := func(variablePrefix ...string) (dnsname.FQDN, error) {
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prefix := strings.Join(append(variablePrefix, prefixConstantParts...), ".")
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return dnsname.ToFQDN(fmt.Sprintf("%s.ip6.arpa", prefix))
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}
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var fqdns []dnsname.FQDN
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if maskBits%4 == 0 {
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dom, _ := makeDomain()
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fqdns = append(fqdns, dom)
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} else {
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domCount := 1 << (maskBits % nibbleLen)
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fqdns = make([]dnsname.FQDN, 0, domCount)
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for i := 0; i < domCount; i++ {
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varNibble := fmt.Sprintf("%x", i)
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dom, err := makeDomain(varNibble)
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if err != nil {
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continue
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}
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fqdns = append(fqdns, dom)
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}
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}
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return fqdns
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}
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@ -1,6 +1,11 @@
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package util
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|
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import "testing"
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import (
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"net/netip"
|
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"testing"
|
||||
|
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"github.com/stretchr/testify/assert"
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)
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func TestNormalizeToFQDNRules(t *testing.T) {
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type args struct {
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@ -141,3 +146,101 @@ func TestCheckForFQDNRules(t *testing.T) {
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})
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}
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}
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func TestMagicDNSRootDomains100(t *testing.T) {
|
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prefixes := []netip.Prefix{
|
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netip.MustParsePrefix("100.64.0.0/10"),
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}
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domains := GenerateMagicDNSRootDomains(prefixes)
|
||||
|
||||
found := false
|
||||
for _, domain := range domains {
|
||||
if domain == "64.100.in-addr.arpa." {
|
||||
found = true
|
||||
|
||||
break
|
||||
}
|
||||
}
|
||||
assert.True(t, found)
|
||||
|
||||
found = false
|
||||
for _, domain := range domains {
|
||||
if domain == "100.100.in-addr.arpa." {
|
||||
found = true
|
||||
|
||||
break
|
||||
}
|
||||
}
|
||||
assert.True(t, found)
|
||||
|
||||
found = false
|
||||
for _, domain := range domains {
|
||||
if domain == "127.100.in-addr.arpa." {
|
||||
found = true
|
||||
|
||||
break
|
||||
}
|
||||
}
|
||||
assert.True(t, found)
|
||||
}
|
||||
|
||||
func TestMagicDNSRootDomains172(t *testing.T) {
|
||||
prefixes := []netip.Prefix{
|
||||
netip.MustParsePrefix("172.16.0.0/16"),
|
||||
}
|
||||
domains := GenerateMagicDNSRootDomains(prefixes)
|
||||
|
||||
found := false
|
||||
for _, domain := range domains {
|
||||
if domain == "0.16.172.in-addr.arpa." {
|
||||
found = true
|
||||
|
||||
break
|
||||
}
|
||||
}
|
||||
assert.True(t, found)
|
||||
|
||||
found = false
|
||||
for _, domain := range domains {
|
||||
if domain == "255.16.172.in-addr.arpa." {
|
||||
found = true
|
||||
|
||||
break
|
||||
}
|
||||
}
|
||||
assert.True(t, found)
|
||||
}
|
||||
|
||||
// Happens when netmask is a multiple of 4 bits (sounds likely).
|
||||
func TestMagicDNSRootDomainsIPv6Single(t *testing.T) {
|
||||
prefixes := []netip.Prefix{
|
||||
netip.MustParsePrefix("fd7a:115c:a1e0::/48"),
|
||||
}
|
||||
domains := GenerateMagicDNSRootDomains(prefixes)
|
||||
|
||||
assert.Len(t, domains, 1)
|
||||
assert.Equal(t, "0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa.", domains[0].WithTrailingDot())
|
||||
}
|
||||
|
||||
func TestMagicDNSRootDomainsIPv6SingleMultiple(t *testing.T) {
|
||||
prefixes := []netip.Prefix{
|
||||
netip.MustParsePrefix("fd7a:115c:a1e0::/50"),
|
||||
}
|
||||
domains := GenerateMagicDNSRootDomains(prefixes)
|
||||
|
||||
yieldsRoot := func(dom string) bool {
|
||||
for _, candidate := range domains {
|
||||
if candidate.WithTrailingDot() == dom {
|
||||
return true
|
||||
}
|
||||
}
|
||||
|
||||
return false
|
||||
}
|
||||
|
||||
assert.Len(t, domains, 4)
|
||||
assert.True(t, yieldsRoot("0.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."))
|
||||
assert.True(t, yieldsRoot("1.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."))
|
||||
assert.True(t, yieldsRoot("2.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."))
|
||||
assert.True(t, yieldsRoot("3.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."))
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user