middleware/reverse: random updates (#516)
* middleware/reverse: random updates Make the documentation somewhat shorter (and hopefully clearer in the process). Also to be on-par with the *auto* middleware, start counting the referenced zones from 1 (instead of 0). Some variable cleanups and use the NextOrFailure in the ServeDNS function. * More TODOs
This commit is contained in:
Miek Gieben
GitHub
parent
87a39a6353
commit
3e196a6d57
5 changed files with 123 additions and 154 deletions
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@ -1,42 +1,43 @@
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# reverse
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The *reverse* middleware allows CoreDNS to respond dynamic to an PTR request and the related A/AAAA request.
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The *reverse* middleware allows CoreDNS to respond dynamicly to an PTR request and the related A/AAAA request.
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## Syntax
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~~~
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reverse NETWORK.. {
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reverse NETWORK... {
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hostname TEMPLATE
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[ttl TTL]
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[fallthrough]
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~~~
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* **NETWORK** one or more CIDR formatted networks to respond on.
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* `hostname` inject the ip and zone to an template for the hostname. Defaults to "ip-{ip}.{zone[0]}". See below for template.
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* `hostname` inject the IP and zone to an template for the hostname. Defaults to "ip-{IP}.{zone[1]}". See below for template.
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* `ttl` defaults to 60
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* `fallthrough` If zone matches and no record can be generated, pass request to the next middleware.
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### Template Syntax
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The template for the hostname is used for generating the PTR for an reverse lookup and matching the forward lookup back to an ip.
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The template for the hostname is used for generating the PTR for an reverse lookup and matching the
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forward lookup back to an IP.
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#### `{ip}`
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This symbol is **required** to work.
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V4 network replaces the "." with an "-". 10.1.1.1 results in "10-1-1-1"
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V6 network removes the ":" and fills the zeros. "ffff::ffff" results in "ffff000000000000000000000000ffff"
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The `{ip}` symbol is **required** to make reverse work.
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For IPv4 lookups the "." is replaced with an "-", i.e.: 10.1.1.1 results in "10-1-1-1"
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With IPv6 lookups the ":" is removed, and any zero ranged are expanded, i.e.:
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"ffff::ffff" results in "ffff000000000000000000000000ffff"
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#### `{zone[i]}`
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This symbol is **optional** to use and can be replaced by a fix zone string.
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The zone will be matched by the configured listener on the server block key.
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`i` needs to be replaced to the index of the configured listener zones, starting with 0.
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`arpa.:53 domain.com.:8053` will resolve `zone{0}` to `arpa.` and `zone{1}` to `domain.com.`
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The `{zone[i]}` symbol is **optional** and can be replaced by a fixed (zone) string.
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The zone will be matched by the zones listed in *this* configuration stanza.
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`i` needs to be replaced to the index of the configured listener zones, starting with 1.
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## Examples
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~~~
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# Serve on port 53
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# match arpa. and compute.internal. to resolv reverse and forward lookup
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.arpa.:53 compute.internal.:53 {
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~~~ txt
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arpa compute.internal {
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# proxy unmatched requests
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proxy . 8.8.8.8
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@ -48,32 +49,25 @@ The zone will be matched by the configured listener on the server block key.
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# AAAA ip-fd010000000000000000000000000001.compute.internal. 3600 fd01::1
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reverse 10.32.0.0/16 fd01::/16 {
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# template of the ip injection to hostname, zone resolved to compute.internal.
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hostname ip-{ip}.{zone[1]}
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hostname ip-{ip}.{zone[2]}
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# set time-to-live of the RR
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ttl 3600
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# forward unanswered or unmatched requests to proxy
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# without this flag, requesting A/AAAA records on compute.internal. will end here
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# Forward unanswered or unmatched requests to proxy # without this flag, requesting A/AAAA
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records on compute.internal. will end here.
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fallthrough
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}
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# cache with ttl timeout
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cache
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}
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~~~
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~~~
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# Serve on port 53
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# listen only on the specific network
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32.10.in-addr.arpa.arpa.:53 arpa.company.org.:53 {
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~~~ txt
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32.10.in-addr.arpa.arpa arpa.company.org {
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reverse 10.32.0.0/16 {
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# template of the ip injection to hostname, zone resolved to arpa.company.org.
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hostname "ip-{ip}.v4.{zone[1]}"
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hostname "ip-{ip}.v4.{zone[2]}"
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# set time-to-live of the RR
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ttl 3600
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# fallthrough is not required, v4.arpa.company.org. will be only answered here
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@ -84,14 +78,7 @@ The zone will be matched by the configured listener on the server block key.
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# its also possible to set fix domain suffix
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hostname ip-{ip}.fix.arpa.company.org.
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# set time-to-live of the RR
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ttl 3600
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}
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# cache with ttl timeout
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cache
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}
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~~~
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@ -1,9 +1,9 @@
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package reverse
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import (
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"bytes"
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"net"
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"regexp"
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"bytes"
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"strings"
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)
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@ -16,32 +16,31 @@ type network struct {
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Fallthrough bool
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}
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// TODO: we might want to get rid of these regexes.
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const hexDigit = "0123456789abcdef"
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const templateNameIP = "{ip}"
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const regexMatchV4 = "((?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\-){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))"
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const regexMatchV6 = "([0-9a-fA-F]{32})"
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// For forward lookup
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// converts the hostname back to an ip, based on the template
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// returns nil if there is no ip found
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// hostnameToIP converts the hostname back to an ip, based on the template
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// returns nil if there is no IP found.
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func (network *network) hostnameToIP(rname string) net.IP {
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var matchedIP net.IP
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// use precompiled regex by setup
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match := network.RegexMatchIP.FindStringSubmatch(rname)
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// regex did not matched
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if (len(match) != 2) {
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if len(match) != 2 {
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return nil
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}
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if network.IPnet.IP.To4() != nil {
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matchedIP = net.ParseIP(strings.Replace(match[1], "-", ".", 4))
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} else {
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// TODO: can probably just allocate a []byte and use that.
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var buf bytes.Buffer
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// convert back to an valid ipv6 string with colons
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for i := 0; i < 8 * 4; i += 4 {
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buf.WriteString(match[1][i:i + 4])
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if (i < 28) {
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for i := 0; i < 8*4; i += 4 {
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buf.WriteString(match[1][i : i+4])
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if i < 28 {
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buf.WriteString(":")
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}
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}
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@ -56,13 +55,9 @@ func (network *network) hostnameToIP(rname string) net.IP {
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return matchedIP
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}
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// For reverse lookup
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// Converts an Ip to an dns compatible hostname and injects it into the template.domain
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func (network *network) ipToHostname(ip net.IP) string {
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var name string
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ipv4 := ip.To4()
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if ipv4 != nil {
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// ipToHostname converts an IP to an DNS compatible hostname and injects it into the template.domain.
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func (network *network) ipToHostname(ip net.IP) (name string) {
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if ipv4 := ip.To4(); ipv4 != nil {
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// replace . to -
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name = uitoa(ipv4[0]) + "-" +
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uitoa(ipv4[1]) + "-" +
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@ -71,11 +66,11 @@ func (network *network) ipToHostname(ip net.IP) string {
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} else {
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// assume v6
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// ensure zeros are present in string
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buf := make([]byte, 0, len(ip) * 4)
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buf := make([]byte, 0, len(ip)*4)
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for i := 0; i < len(ip); i++ {
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v := ip[i]
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buf = append(buf, hexDigit[v >> 4])
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buf = append(buf, hexDigit[v & 0xF])
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buf = append(buf, hexDigit[v>>4])
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buf = append(buf, hexDigit[v&0xF])
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}
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name = string(buf)
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}
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@ -93,7 +88,7 @@ func uitoa(val uint8) string {
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i := len(buf) - 1
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for val >= 10 {
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q := val / 10
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buf[i] = byte('0' + val - q * 10)
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buf[i] = byte('0' + val - q*10)
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i--
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val = q
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}
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@ -104,20 +99,12 @@ func uitoa(val uint8) string {
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type networks []network
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// implements the sort interface
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func (slice networks) Len() int {
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return len(slice)
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}
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func (n networks) Len() int { return len(n) }
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func (n networks) Swap(i, j int) { n[i], n[j] = n[j], n[i] }
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// implements the sort interface
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// cidr closer to the ip wins (by netmask)
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func (slice networks) Less(i, j int) bool {
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isize, _ := slice[i].IPnet.Mask.Size()
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jsize, _ := slice[j].IPnet.Mask.Size()
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func (n networks) Less(i, j int) bool {
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isize, _ := n[i].IPnet.Mask.Size()
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jsize, _ := n[j].IPnet.Mask.Size()
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return isize > jsize
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}
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// implements the sort interface
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func (slice networks) Swap(i, j int) {
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slice[i], slice[j] = slice[j], slice[i]
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}
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@ -3,31 +3,33 @@ package reverse
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import (
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"net"
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"github.com/miekg/coredns/request"
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/coredns/middleware/pkg/dnsutil"
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"github.com/miekg/coredns/request"
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"github.com/miekg/dns"
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"golang.org/x/net/context"
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)
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// Reverse provides dynamic reverse dns and the related forward rr
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// Reverse provides dynamic reverse DNS and the related forward RR.
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type Reverse struct {
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Next middleware.Handler
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Networks networks
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}
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// ServeDNS implements the middleware.Handler interface.
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func (reverse Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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var rr dns.RR
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nextHandler := true
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func (re Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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var (
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rr dns.RR
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fallThrough bool
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)
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state := request.Request{W: w, Req: r}
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m := new(dns.Msg)
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m.SetReply(r)
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m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
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switch state.QType(){
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switch state.QType() {
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case dns.TypePTR:
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address := dnsutil.ExtractAddressFromReverse(state.Name())
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@ -38,9 +40,9 @@ func (reverse Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dn
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ip := net.ParseIP(address)
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// loop through the configured networks
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for _, n := range reverse.Networks {
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if (n.IPnet.Contains(ip)) {
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nextHandler = n.Fallthrough
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for _, n := range re.Networks {
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if n.IPnet.Contains(ip) {
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fallThrough = n.Fallthrough
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rr = &dns.PTR{
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Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: n.TTL},
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Ptr: n.ipToHostname(ip),
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@ -50,9 +52,9 @@ func (reverse Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dn
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}
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case dns.TypeA:
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for _, n := range reverse.Networks {
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for _, n := range re.Networks {
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if dns.IsSubDomain(n.Zone, state.Name()) {
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nextHandler = n.Fallthrough
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fallThrough = n.Fallthrough
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// skip if requesting an v4 address and network is not v4
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if n.IPnet.IP.To4() == nil {
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@ -71,9 +73,9 @@ func (reverse Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dn
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}
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case dns.TypeAAAA:
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for _, n := range reverse.Networks {
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for _, n := range re.Networks {
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if dns.IsSubDomain(n.Zone, state.Name()) {
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nextHandler = n.Fallthrough
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fallThrough = n.Fallthrough
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// Do not use To16 which tries to make v4 in v6
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if n.IPnet.IP.To4() != nil {
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@ -93,13 +95,8 @@ func (reverse Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dn
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}
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if rr == nil {
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if reverse.Next == nil || !nextHandler {
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// could not resolv
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w.WriteMsg(m)
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return dns.RcodeNameError, nil
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}
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return reverse.Next.ServeDNS(ctx, w, r)
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if rr == nil && !fallThrough {
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return middleware.NextOrFailure(re.Name(), re.Next, ctx, w, r)
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}
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m.Answer = append(m.Answer, rr)
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@ -109,6 +106,4 @@ func (reverse Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dn
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}
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// Name implements the Handler interface.
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func (reverse Reverse) Name() string {
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return "reverse"
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}
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func (re Reverse) Name() string { return "reverse" }
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@ -2,10 +2,10 @@ package reverse
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import (
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"net"
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"sort"
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"strings"
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"strconv"
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"regexp"
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"sort"
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"strconv"
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"strings"
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"github.com/miekg/coredns/core/dnsserver"
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"github.com/miekg/coredns/middleware"
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@ -27,7 +27,7 @@ func setupReverse(c *caddy.Controller) error {
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}
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dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
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return Reverse{Next: next, Networks:networks}
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return Reverse{Next: next, Networks: networks}
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})
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return nil
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@ -56,7 +56,7 @@ func reverseParse(c *caddy.Controller) (networks, error) {
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}
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_, ipnet, err := net.ParseCIDR(cidr)
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if err != nil {
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return nil, c.Errf("%v needs to be an CIDR formatted Network\n", cidr)
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return nil, c.Errf("network needs to be CIDR formatted: %q\n", cidr)
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}
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cidrs = append(cidrs, ipnet)
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}
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@ -66,7 +66,7 @@ func reverseParse(c *caddy.Controller) (networks, error) {
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// set defaults
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var (
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template = "ip-" + templateNameIP + ".{zone[0]}"
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template = "ip-" + templateNameIP + ".{zone[1]}"
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ttl = 60
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fall = false
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)
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@ -98,7 +98,9 @@ func reverseParse(c *caddy.Controller) (networks, error) {
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// prepare template
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// replace {zone[index]} by the listen zone/domain of this config block
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for i, zone := range zones {
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template = strings.Replace(template, "{zone[" + string(i + 48) + "]}", zone, 1)
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// TODO: we should be smarter about actually replacing this. This works, but silently allows "zone[-1]"
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// for instance.
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template = strings.Replace(template, "{zone["+strconv.Itoa(i+1)+"]}", zone, 1)
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}
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if !strings.HasSuffix(template, ".") {
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template += "."
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@ -107,7 +109,7 @@ func reverseParse(c *caddy.Controller) (networks, error) {
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// extract zone from template
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templateZone := strings.SplitAfterN(template, ".", 2)
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if len(templateZone) != 2 || templateZone[1] == "" {
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return nil, c.Errf("Cannot find domain in template '%v'", template)
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return nil, c.Errf("cannot find domain in template '%v'", template)
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}
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// Create for each configured network in this stanza
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@ -122,9 +124,8 @@ func reverseParse(c *caddy.Controller) (networks, error) {
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regexp.QuoteMeta(template), // escape dots
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regexp.QuoteMeta(templateNameIP),
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regexIP,
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1, ) + "$")
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1) + "$")
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if err != nil {
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// invalid regex
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return nil, err
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}
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|
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@ -1,10 +1,10 @@
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package reverse
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import (
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"testing"
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"net"
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"reflect"
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"regexp"
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"testing"
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"github.com/mholt/caddy"
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)
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@ -19,7 +19,7 @@ func TestSetupParse(t *testing.T) {
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regexIpv6dynamic, _ := regexp.Compile("^dynamic-" + regexMatchV6 + "-intern\\.dynamic\\.domain\\.com\\.$")
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regexIpv4vpndynamic, _ := regexp.Compile("^dynamic-" + regexMatchV4 + "-vpn\\.dynamic\\.domain\\.com\\.$")
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serverBlockKeys := []string{"domain.com.:8053", "dynamic.domain.com.:8053" }
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serverBlockKeys := []string{"domain.com.:8053", "dynamic.domain.com.:8053"}
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tests := []struct {
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inputFileRules string
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|
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@ -98,11 +98,11 @@ func TestSetupParse(t *testing.T) {
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},
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{
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`reverse fd01::/64 {
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hostname dynamic-{ip}-intern.{zone[1]}
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hostname dynamic-{ip}-intern.{zone[2]}
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||||
ttl 50
|
||||
}
|
||||
reverse 10.1.1.0/24 {
|
||||
hostname dynamic-{ip}-vpn.{zone[1]}
|
||||
hostname dynamic-{ip}-vpn.{zone[2]}
|
||||
fallthrough
|
||||
}`,
|
||||
false,
|
||||
|
|
@ -111,7 +111,7 @@ func TestSetupParse(t *testing.T) {
|
|||
Template: "dynamic-{ip}-intern.dynamic.domain.com.",
|
||||
Zone: "dynamic.domain.com.",
|
||||
TTL: 50,
|
||||
RegexMatchIP:regexIpv6dynamic,
|
||||
RegexMatchIP: regexIpv6dynamic,
|
||||
Fallthrough: false,
|
||||
}, network{
|
||||
IPnet: net4,
|
||||
|
|
@ -119,13 +119,13 @@ func TestSetupParse(t *testing.T) {
|
|||
Zone: "dynamic.domain.com.",
|
||||
TTL: 60,
|
||||
RegexMatchIP: regexIpv4vpndynamic,
|
||||
Fallthrough:true,
|
||||
Fallthrough: true,
|
||||
}},
|
||||
},
|
||||
{
|
||||
// multiple networks in one stanza
|
||||
`reverse fd01::/64 10.1.1.0/24 {
|
||||
hostname dynamic-{ip}-intern.{zone[1]}
|
||||
hostname dynamic-{ip}-intern.{zone[2]}
|
||||
ttl 50
|
||||
fallthrough
|
||||
}`,
|
||||
|
|
@ -135,7 +135,7 @@ func TestSetupParse(t *testing.T) {
|
|||
Template: "dynamic-{ip}-intern.dynamic.domain.com.",
|
||||
Zone: "dynamic.domain.com.",
|
||||
TTL: 50,
|
||||
RegexMatchIP:regexIpv6dynamic,
|
||||
RegexMatchIP: regexIpv6dynamic,
|
||||
Fallthrough: true,
|
||||
}, network{
|
||||
IPnet: net4,
|
||||
|
|
@ -159,11 +159,10 @@ func TestSetupParse(t *testing.T) {
|
|||
Template: "dynamic-{ip}-intern.dynamic.domain.com.",
|
||||
Zone: "dynamic.domain.com.",
|
||||
TTL: 300,
|
||||
RegexMatchIP:regexIpv6dynamic,
|
||||
RegexMatchIP: regexIpv6dynamic,
|
||||
Fallthrough: true,
|
||||
}},
|
||||
},
|
||||
|
||||
}
|
||||
for i, test := range tests {
|
||||
c := caddy.NewTestController("dns", test.inputFileRules)
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue