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Nick Thomas
2015-01-10 02:01:24 +00:00
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GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Preamble
The licenses for most software are designed to take away your
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Foundation's software and to any other program whose authors commit to
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When we speak of free software, we are referring to freedom, not
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0. This License applies to any program or other work which contains
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and give any other recipients of the Program a copy of this License
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certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
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of the General Public License from time to time. Such new versions will
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NO WARRANTY
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OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
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YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
<signature of Ty Coon>, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into
proprietary programs. If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library. If this is what you want to do, use the GNU Lesser General
Public License instead of this License.

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go-pdns
*******
Simple Go libraries to interact with PowerDNS ( https://www.powerdns.com/ ).
Currently contains an implementation of the powerdns-pipebackend protocol and a
library to ease developing backends in Go. See pipe/dsl/dsl.go for usage
examples.
APIs / etc are not set in stone yet, patches welcome.
Contact: Nick Thomas <nick@bytemark.co.uk>

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// Copyright 2015 Bytemark Computer Consulting Ltd. All rights reserved
// Licensed under the GNU General Public License, version 2. See the LICENSE
// file for more details
// Handler for the PowerDNS pipebackend protocol, as documented here:
// https://doc.powerdns.com/md/authoritative/backend-pipe/
//
// Can speak all three (at time of writing) protocol versions.
//
// Usage:
//
// backend := backend.New(
package backend
import (
"bufio"
"errors"
"fmt"
"io"
"strconv"
"strings"
)
type Backend struct {
// The text the backend will serve to a successful hello message
Banner string
// The protocol version negotiated with the remote end
ProtocolVersion int
io *bufio.ReadWriter
}
// A callback of this type is executed whenever a query is received. If an error
// is returned, the responses are ignored and the error text is returned to the
// backend. Otherwise, the responses are serialised and sent back in order.
type Callback func(b *Backend, q *Query) ([]*Response, error)
// Build a new backend object. The banner is reported to the client upon
// successful negotiation; the io can be anything.
func New(r io.Reader, w io.Writer, banner string) *Backend {
io := bufio.NewReadWriter(
bufio.NewReader(r),
bufio.NewWriter(w),
)
return &Backend{Banner: banner, io: io}
}
// Does initial handshake with peer. Returns nil, or an error
// Note that the pipebackend protocol documentation states that if negotiation
// fails, the process should retry, not exit itself.
func (b *Backend) Negotiate() error {
hello, err := b.io.ReadString('\n')
if err != nil {
return err
}
// We're not interested in the trailing newlines
parts := strings.Split(strings.TrimRight(hello, "\r\n"), "\t")
if len(parts) != 2 || parts[0] != "HELO" {
return errors.New("Bad hello from client")
}
version, err := strconv.Atoi(parts[1])
if version < 1 || version > 3 || err != nil {
return errors.New("Unknown protocol version requested")
}
_, err = b.io.WriteString(fmt.Sprintf("OK\t%s\n", b.Banner))
if err == nil {
err = b.io.Flush()
}
if err == nil {
b.ProtocolVersion = version
}
return err
}
func (b *Backend) handleQ(data string, callback Callback) ([]*Response, error) {
query := Query{ProtocolVersion: b.ProtocolVersion}
err := query.fromData(data)
if err != nil {
return nil, err
}
return callback(b, &query)
}
// TODO
func (b *Backend) handleAXFR() ([]*Response, error) {
return nil, errors.New("AXFR requests not supported")
}
// Reads lines in a loop, processing them by executing the provided callback
// and writing appropriate output in response, sequentially, until we hit an
// error or our IO hits EOF
func (b *Backend) Run(callback Callback) error {
responses := make([]*Response, 0)
for {
line, err := b.io.ReadString('\n')
if err != nil {
if err == io.EOF {
return nil
}
return err
}
parts := strings.SplitN(strings.TrimRight(line, "\n"), "\t", 2)
if len(parts) == 2 {
}
switch parts[0] {
case "Q":
responses, err = b.handleQ(parts[1], callback)
case "PING":
responses, err = nil, nil // We just need to return END
case "AXFR":
responses, err = b.handleAXFR()
default:
responses, err = nil, errors.New("Bad command")
}
if err != nil {
// avoid protocol errors
clean := strings.Replace(err.Error(), "\n", " ", -1)
msg := fmt.Sprintf("LOG\tError handling line: %s\nFAIL\n", clean)
_, err := b.io.WriteString(msg)
if err != nil {
return fmt.Errorf("%s while writing FAIL response", err)
}
//
err = b.io.Flush()
if err != nil {
return fmt.Errorf("%s while flushing FAIL response", err)
}
continue
}
// DATA (if there are any records to return)
for _, response := range responses {
// Always output a line of the right protocol version
// TODO: panic if it's set to a wrong non-zero value?
response.ProtocolVersion = b.ProtocolVersion
data, err := response.String()
if err != nil {
data = "LOG\tError serialising response: " + err.Error() + "\n"
}
_, err = b.io.WriteString(data)
if err != nil {
return fmt.Errorf("%s while writing DATA response", err)
}
}
// END
_, err = b.io.WriteString("END\n")
if err == nil {
err = b.io.Flush()
}
if err != nil {
return fmt.Errorf("%s while writing END", err)
}
}
// We should never hit this at the moment.
// TODO: graceful signal handling - intercept and ensure current query
// completes before breaking the above loop and returning nil here
return nil
}

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package backend_test
import (
h "../test_helpers"
"bytes"
"errors"
"fmt"
. "github.com/BytemarkHosting/go-pdns/pipe/backend"
"strings"
"testing"
)
// Test serializing Query & Response instances - we use them in the tests
func TestQueryStringV1(t *testing.T) {
h.AssertEqualString(
t, "Q\texample.com\tIN\tANY\t-1\t127.0.0.2\n",
h.FakeQueryString(t, 1), "V1 query serialisation problem",
)
}
func TestQueryStringV2(t *testing.T) {
h.AssertEqualString(
t, "Q\texample.com\tIN\tANY\t-1\t127.0.0.2\t127.0.0.1\n",
h.FakeQueryString(t, 2), "V2 query serialisation problem",
)
}
func TestQueryStringV3(t *testing.T) {
h.AssertEqualString(
t, "Q\texample.com\tIN\tANY\t-1\t127.0.0.2\t127.0.0.1\t127.0.0.3\n",
h.FakeQueryString(t, 3), "V3 query serialisation problem",
)
}
// Ensure we serialize Response instances correctly - we use them in the tests
func TestResponseStringV1andV2(t *testing.T) {
exemplar := "DATA\texample.com\tIN\tANY\t3600\t-1\tfoo\n"
h.AssertEqualString(t, exemplar, h.FakeResponseString(t, 1), "V1 response serialisation problem")
h.AssertEqualString(t, exemplar, h.FakeResponseString(t, 2), "V2 response serialisation problem")
}
func TestResponseStringV3(t *testing.T) {
h.AssertEqualString(
t, "DATA\t24\tauth\texample.com\tIN\tANY\t3600\t-1\tfoo\n",
h.FakeResponseString(t, 3), "V3 response serialisation problem",
)
}
func BuildAndNegotiate(t *testing.T, protoVersion int) (*Backend, *bytes.Buffer, *bytes.Buffer) {
r := bytes.NewBufferString(fmt.Sprintf("HELO\t%d\n", protoVersion))
w := &bytes.Buffer{}
b := New(r, w, "Testing Backend")
h.RefuteError(t, b.Negotiate(), "Negotiation failed")
h.AssertEqualInt(t, protoVersion, b.ProtocolVersion, "Bad protocol version")
h.AssertEqualString(t, "OK\tTesting Backend\n", w.String(), "Bad response to HELO")
w.Reset()
return b, r, w
}
func AssertRun(t *testing.T, b *Backend, f Callback) {
err := b.Run(f)
h.RefuteError(t, err, "Running backend")
}
func AssertProtocolVersionNegotiation(t *testing.T, protoVersion int) {
b, r, w := BuildAndNegotiate(t, protoVersion)
r.WriteString(h.FakeQueryString(t, protoVersion))
// We also test that the negotiated version can be handled
AssertRun(t, b, h.EmptyDispatch)
h.AssertEqualString(t, "END\n", w.String(), "Unexpected response")
w.Reset()
exp := fmt.Sprintf(
"LOG\tError handling line: v%d query should have %d data parts\nFAIL\n",
protoVersion, protoVersion+4,
)
// Test a short Q
r.WriteString("Q\tfoo\n")
AssertRun(t, b, h.EmptyDispatch)
h.AssertEqualString(t, exp, w.String(), "Unexpected response")
w.Reset()
// test a long Q
long := strings.TrimRight(h.FakeQueryString(t, protoVersion), "\n") + "\tfoo\n"
r.WriteString(long)
AssertRun(t, b, h.EmptyDispatch)
h.AssertEqualString(t, exp, w.String(), "Unexpected response")
}
func TestNegotiatedVersion1(t *testing.T) {
AssertProtocolVersionNegotiation(t, 1)
}
func TestNegotiatedVersion2(t *testing.T) {
AssertProtocolVersionNegotiation(t, 2)
}
func TestNegotiatedVersion3(t *testing.T) {
AssertProtocolVersionNegotiation(t, 3)
}
func TestQueriesArePassedToDispatcher(t *testing.T) {
b, r, w := BuildAndNegotiate(t, 3)
var outQ *Query
runs := 0
expected := h.FakeQueryString(t, 3)
r.WriteString(expected)
AssertRun(t, b, func(b *Backend, q *Query) ([]*Response, error) {
runs = runs + 1
outQ = q
return nil, nil
})
h.AssertEqualInt(t, 1, runs, "Exactly one dispatch callback expected")
txt, _ := outQ.String()
h.AssertEqualString(t, expected, txt, "Wrong query dispatched")
h.AssertEqualString(t, "END\n", w.String(), "Unexpected response")
}
func TestResponsesFromDispatcherArePassedToAsker(t *testing.T) {
b, r, w := BuildAndNegotiate(t, 3)
r.WriteString(h.FakeQueryString(t, 3))
fr := h.FakeResponse(3)
AssertRun(t, b, func(b *Backend, q *Query) ([]*Response, error) {
return []*Response{fr, fr}, nil
})
exp := fmt.Sprintf("%s%sEND\n", h.FakeResponseString(t, 3), h.FakeResponseString(t, 3))
h.AssertEqualString(t, exp, w.String(), "Bad response")
}
func TestErrorFromDispatcherSuppressesResponses(t *testing.T) {
b, r, w := BuildAndNegotiate(t, 3)
r.WriteString(h.FakeQueryString(t, 3))
fr := h.FakeResponse(3)
AssertRun(t, b, func(b *Backend, q *Query) ([]*Response, error) {
return []*Response{fr, fr}, errors.New("Test\nerror")
})
h.AssertEqualString(t, "LOG\tError handling line: Test error\nFAIL\n", w.String(), "Bad response")
}
func TestHandlesPing(t *testing.T) {
b, r, w := BuildAndNegotiate(t, 3)
r.WriteString("PING\n")
AssertRun(t, b, h.EmptyDispatch)
h.AssertEqualString(t, "END\n", w.String(), "Bad response")
}
func TestAXFRIsTODO(t *testing.T) {
b, r, w := BuildAndNegotiate(t, 3)
r.WriteString("AXFR\n")
AssertRun(t, b, h.EmptyDispatch)
h.AssertEqualString(t, "LOG\tError handling line: AXFR requests not supported\nFAIL\n", w.String(), "Bad response")
}
func TestUnknownCommand(t *testing.T) {
b, r, w := BuildAndNegotiate(t, 3)
r.WriteString("GOGOGO\n")
AssertRun(t, b, h.EmptyDispatch)
h.AssertEqualString(t, "LOG\tError handling line: Bad command\nFAIL\n", w.String(), "Bad response")
}

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package backend
import (
"errors"
"fmt"
"strings"
)
// Represents a query received by the backend. Certain fields may be blank,
// depending on negotiated protocol version - which is stored in ProtocolVersion
//
// QName, QClass, QType, Id and RemoteIpAddress are present in all versions
// LocalIpAddress was added in version 2
// EdnsSubnetAddress was added in version 3
type Query struct {
ProtocolVersion int
QName string
QClass string
QType string
Id string
RemoteIpAddress string
LocalIpAddress string
EdnsSubnetAddress string
}
func (q *Query) fromData(data string) (err error) {
parts := strings.Split(data, "\t")
// ugh
switch q.ProtocolVersion {
case 1:
if len(parts) != 5 {
return errors.New("v1 query should have 5 data parts")
}
case 2:
if len(parts) != 6 {
return errors.New("v2 query should have 6 data parts")
}
q.LocalIpAddress = parts[5]
case 3:
if len(parts) != 7 {
return errors.New("v3 query should have 7 data parts")
}
q.LocalIpAddress = parts[5]
q.EdnsSubnetAddress = parts[6]
default:
return errors.New("Unknown protocol version in query")
}
// common
q.QName = parts[0]
q.QClass = parts[1]
q.QType = parts[2]
q.Id = parts[3]
q.RemoteIpAddress = parts[4]
return nil
}
func (q *Query) String() (string, error) {
if q.ProtocolVersion < 1 || q.ProtocolVersion > 3 {
return "", errors.New("Unknown protocol version in query")
}
switch q.ProtocolVersion {
case 1:
return fmt.Sprintf(
"Q\t%s\t%s\t%s\t%s\t%s\n",
q.QName, q.QClass, q.QType, q.Id, q.RemoteIpAddress,
), nil
case 2:
return fmt.Sprintf(
"Q\t%s\t%s\t%s\t%s\t%s\t%s\n",
q.QName, q.QClass, q.QType, q.Id, q.RemoteIpAddress,
q.LocalIpAddress,
), nil
case 3:
return fmt.Sprintf(
"Q\t%s\t%s\t%s\t%s\t%s\t%s\t%s\n",
q.QName, q.QClass, q.QType, q.Id, q.RemoteIpAddress,
q.LocalIpAddress, q.EdnsSubnetAddress,
), nil
}
return "", errors.New("Unknown protocol version in query")
}

41
pipe/backend/response.go Normal file
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package backend
import (
"errors"
"fmt"
)
// A response to be sent back in answer to a query. Again, some fields may be
// blank, depending on protocol version.
//
// QName, QClass, QType, TTL, Id and Content are present in all versions
// No additions in version 2
// ScopeBits and Auth were added in version 3
type Response struct {
ProtocolVersion int
ScopeBits string
Auth string
QName string
QClass string
QType string
TTL string
Id string
Content string
}
// Gives the response in a serialized form suitable for squirting on the wire
func (r *Response) String() (string, error) {
switch r.ProtocolVersion {
case 1, 2:
return fmt.Sprintf(
"DATA\t%s\t%s\t%s\t%s\t%s\t%s\n",
r.QName, r.QClass, r.QType, r.TTL, r.Id, r.Content,
), nil
case 3:
return fmt.Sprintf(
"DATA\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\n",
r.ScopeBits, r.Auth, r.QName, r.QClass, r.QType, r.TTL, r.Id, r.Content,
), nil
}
return "", errors.New("Unknown protocol version in response")
}

59
pipe/dsl/context.go Normal file
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package dsl
import (
"github.com/BytemarkHosting/go-pdns/pipe/backend"
"strconv"
)
// Callbacks are run with a context instance, which allows them to accumulate
// answers while maintaining a short type signature. It will also make
// concurrent callbacks easier, when we handle that, but for now one context
// is maintained across all callbacks for a particular query
type Context struct {
// Replies that don't specify a TTL will be given this instead.
DefaultTTL int
// The query that triggered this callback run. Note that its QType
// member may be "ANY"
Query *backend.Query
// QType this callback is being run as. Matches the qtype field given
// with the callback at the time DSL.Register was called
QType string
// The callback is registered with a regexp; if that regexp contains
// any match groups, then the matched text is placed here.
Matches []string
// Set this if an error has been encountered; no more callbacks will be
// run, and the error text (only) will be reported to the backend.
Error error
// Answers to be sent to the backend are stored here. Context.Reply()
// calls, etc, generate answers and put them here, for instance.
// If multiple callbacks are being run, then later callbacks will be
// able to see the answers earlier ones generated (for now)
Answers []*backend.Response
}
// Add an answer, using default QName and TTL for the query
func (c *Context) Reply(content string) {
c.ReplyExtra(c.Query.QName, content, c.DefaultTTL)
}
// Add an answer, using the default QName but specifying a particular TTL
func (c *Context) ReplyTTL(content string, ttl int) {
c.ReplyExtra(c.Query.QName, content, ttl)
}
// Add an answer, specifying both QName and TTL.
func (c *Context) ReplyExtra(qname, content string, ttl int) {
c.Answers = append(c.Answers, &backend.Response{
QName: qname,
QClass: c.Query.QClass,
QType: c.QType, // q.Query.QType may == "ANY"
Id: c.Query.Id,
Content: content,
TTL: strconv.Itoa(ttl),
})
}

223
pipe/dsl/dsl.go Normal file
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// Copyright 2015 Bytemark Computer Consulting Ltd. All rights reserved
// Licensed under the GNU General Public License, version 2. See the LICENSE
// file for more details
// Simple DSL for pipebackend. Usage:
//
// // Create new handle. You have to specify a default TTL here.
// x := dsl.New()
// root := regexp.QuoteMeta("example.com")
//
// // most zones need SOA + NS records
// x.SOA(root, func(c *dsl.Context) {
// c.Reply("ns1.example.com hostmaster.example.com 1 3600 1800 86400 3600")
// })
//
// // Zones need NS records too. All replies will be returned
// x.NS(root, func(c *dsl.Context) {
// c.Reply("ns1.example.com")
// c.Reply("ns2.example.com")
// c.Reply("ns3.example.com")
// })
//
// // You don't have to use anonymous functions, of course
// func answer(c *dsl.Context) {
// switch c.Query.QType {
// case "A" : c.Reply("169.254.0.1")
// case "AAAA": c.Reply("fe80::1" )
// }
// }
// x.A(root, answer)
// x.AAAA(root, answer)
//
// // Setting c.Error at any point will suppress *all* replies from being
// // sent back. Instead, a FAIL response with the c.Error.Error() as the
// // content is returned to powerdns
// x.SSHFP(root, func(c *dsl.Context) {
// c.Reply("1 1 f1d2d2f924e986ac86fdf7b36c94bcdf32beec15")
// c.Error = errors.New("Don't use SSHFP on unsigned zones")
// c.Reply("1 2 e242ed3bffccdf271b7fbaf34ed72d089537b42f")
// })
//
// // You can do anything in a callback, but be aware that powerdns has a
// // time limit on responses and there is no request concurrency within a
// // single pipe connection. pdns achieves concurrency through multiple
// // backend connections instead
// c := make(chan string)
// x.MX(root, func(c *dsl.Context) {
// c.Reply(<-c)
// })
//
// // If your regexp includes capture groups, they are quoted back to you.
// // Here's a simple DNS echo server. Note the use of ReplyExtra to allow
// // a non-default TTL to be set.
// //
// // Don't forget: DNS is supposed to be case-insensitive. Be careful.
// c.TXT(`(.*)\.` + root, func(c *dsl.Context) {
// c.ReplyTTL(c.Query.QName, c.Matches[0], 0)
// })
//
// // Dispatch is up to you. It will probably look like this, but you
// // might want to add logging around the request or something more
// // complicated (different DSL instance depending on backend version?)
// func doit(b *backend.Backend, q *backend.Query) ([]*backend.Response, error) {
// if q.QClass == "IN" {
// return x.Lookup(q)
// }
// return nil, errors.New("Only IN QClass is supported")
// }
//
// pipe := backend.New( r, w, "Example backend" )
// err1 := pipe.Negotiate() // do check for errors
// err2 := pipe.Run(doit)
//
//
//
package dsl
import (
"github.com/BytemarkHosting/go-pdns/pipe/backend"
"regexp"
)
// Instances of this struct are used to hold onto registered callbacks, etc.
type DSL struct {
callbacks map[string][]callbackNode
qtypeSort []string
defaultTTL int
beforeCallback Callback
}
// Get a new builder with a default TTL of one hour
func New() *DSL {
return NewWithTTL(3600)
}
// Get a new builder, specifying a default TTL explicitly
func NewWithTTL(ttl int) *DSL {
return &DSL{
callbacks: make(map[string][]callbackNode),
qtypeSort: make([]string, 0),
defaultTTL: ttl,
}
}
// Callbacks are registered against the DSL instance and run against incoming
// queries if the regexp they are registered with matches the QName of the query
type Callback func(c *Context)
type callbackNode struct {
matcher *regexp.Regexp
fn Callback
}
// Register a callback to run before every request. Set c.Error to halt
// processing, or mutate the context however you like.
func (d *DSL) Before(f Callback) {
d.beforeCallback = f
}
// Register a callback to be run whenever a query with a QName matching the
// regular expression comes in. The regex is provided as a string (matcher)
// to keep ordinary invocations short; it's compiled immediately with
// regexp.MustCompile. Don't forget to anchor your regexes!
//
// If match groups are included in the regex, then any matched text is placed in
// the Context the callback receives.
//
// Callbacks are run with slightly obtuse ordering: all callbacks of a qtype
// are run in the order they were registered. We iterate the list of qtypes
// in the order that a callback with a matching qtype was *first* registered.
// If your pdns server has the "noshuffle" configuration directive, the order
// will be reflected in the responses returned by it; future concurrent DSL
// should maintain this ordering.
func (d *DSL) Register(qtype string, re *regexp.Regexp, f Callback) {
// Maintain our obtuse sense of order
alreadyIn := false
for _, prospect := range d.qtypeSort {
if prospect == qtype {
alreadyIn = true
break
}
}
if !alreadyIn {
d.qtypeSort = append(d.qtypeSort, qtype)
}
node := callbackNode{matcher: re, fn: f}
d.callbacks[qtype] = append(d.callbacks[qtype], node)
}
// Once we're concurrent, this method will create the context and return it
func (d *DSL) runNode(c *Context, node *callbackNode) {
matches := node.matcher.FindStringSubmatch(c.Query.QName)
if matches != nil && len(matches) > 0 {
// Probably unnecessary, but ensure that the previous value of
// Matches is preserved. This could also be = nil
oldmatches := c.Matches
defer func(c *Context) { c.Matches = oldmatches }(c)
// The first match is the whole thing, followed by the capture
// groups. We're only interested in the latter.
c.Matches = matches[1:]
if d.beforeCallback != nil {
d.beforeCallback(c)
}
if c.Error == nil {
node.fn(c)
}
}
}
// Run all registered callbacks against the query. If any callbacks report an
// error, we halt and return the error only (partially constructed responses are
// discarded).
//
// For now, callbacks are run sequentially, rather than in parallel. There could
// be a speedup to running each callback in its own goroutine. Currently, all
// callbacks share the same context instance; we'd have to change that if we
// ran them in parallel.
func (d *DSL) Lookup(q *backend.Query) ([]*backend.Response, error) {
c := Context{
DefaultTTL: d.defaultTTL,
Query: q,
Answers: make([]*backend.Response, 0),
Error: nil,
}
var runOn []string
if q.QType == "ANY" {
runOn = d.qtypeSort
} else {
runOn = []string{q.QType}
}
for _, qtype := range runOn {
c.QType = qtype
for _, node := range d.callbacks[qtype] {
d.runNode(&c, &node)
if c.Error != nil {
return nil, c.Error
}
}
}
return c.Answers, nil
}
// Reports the registered callbacks, in order. Handy for testing or status.
func (d *DSL) String() string {
out := ""
for _, qtype := range d.qtypeSort {
out = out + qtype + "\t:"
for _, node := range d.callbacks[qtype] {
out = out + "\t" + node.matcher.String() + "\n"
}
}
return out
}

1163
pipe/dsl/dsl_helpers.go Normal file
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181
pipe/dsl/dsl_test.go Normal file
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package dsl_test
import (
"errors"
"fmt"
"github.com/BytemarkHosting/go-pdns/pipe/backend"
. "github.com/BytemarkHosting/go-pdns/pipe/dsl"
h "github.com/BytemarkHosting/go-pdns/pipe/test_helpers"
"strings"
"testing"
)
func ReplyHandler(x string) func(c *Context) {
return func(c *Context) { c.Reply(x) }
}
func NullHandler(c *Context) {}
var ErrorReplyError = errors.New("Foo")
func ErrorReplyHandler(c *Context) { c.Error = ErrorReplyError }
func SOAQuery() *backend.Query {
q := h.FakeQuery(3)
q.QName = "example.com"
q.QType = "SOA"
return q
}
func AssertTableEntry(t *testing.T, d *DSL, qtype, matcher, msg string) {
table := qtype + "\t:\t" + matcher + "\n"
h.AssertEqualString(t, table, d.String(), msg)
}
func AssertLookup(t *testing.T, d *DSL, q *backend.Query, n int, err error) []*backend.Response {
rsp, rspErr := d.Lookup(q)
if err == nil {
h.RefuteError(t, err, "Lookup shouldn't return error")
} else if rspErr == nil {
t.Logf("Expected error %s but no error was returned", err)
t.FailNow()
} else {
h.AssertEqualString(t, err.Error(), rspErr.Error(), "Expected error not returned")
}
rspStrs := []string{}
for _, r := range rsp {
r.ProtocolVersion = 1
str, err := r.String()
h.RefuteError(t, err, "sanity")
rspStrs = append(rspStrs, str)
}
h.AssertEqualInt(t, n, len(rsp), fmt.Sprintf("One response expected, got:\n%s", strings.Join(rspStrs, "")))
return rsp
}
// Don't test all the autogenerated helpers explicitly, just a common one.
func TestAutogeneratedExampleRegistersCorrectCallbackWhenRun(t *testing.T) {
d := New()
d.SOA(`example\.com`, NullHandler)
AssertTableEntry(t, d, "SOA", `^(?i)example\.com$`, "SOA callback not registered")
}
func TestDefaultTTLFromNewIsOneHour(t *testing.T) {
d := New()
d.SOA(`*`, ReplyHandler("Foo"))
rsp := AssertLookup(t, d, SOAQuery(), 1, nil)
h.AssertEqualString(t, "3600", rsp[0].TTL, "Default TTL not honoured")
}
func TestAlternativeTTLCanBeSpecifiedUsingNewWithTTL(t *testing.T) {
d := NewWithTTL(86400)
d.SOA(`*`, ReplyHandler("Foo"))
rsp := AssertLookup(t, d, SOAQuery(), 1, nil)
h.AssertEqualString(t, "86400", rsp[0].TTL, "Custom TTL not honoured")
}
func TestBeforeCallbackIsCalledIfSpecified(t *testing.T) {
d := New()
d.Before(ReplyHandler("Before"))
d.SOA(`*`, ReplyHandler("SOA 1"))
d.SOA(`*`, ReplyHandler("SOA 2"))
rsp := AssertLookup(t, d, SOAQuery(), 4, nil)
h.AssertEqualString(t, "Before", rsp[0].Content, "First Before not called")
h.AssertEqualString(t, "SOA 1", rsp[1].Content, "First SOA not called")
h.AssertEqualString(t, "Before", rsp[2].Content, "Second Before not called")
h.AssertEqualString(t, "SOA 2", rsp[3].Content, "Second SOA not called")
}
func TestLookupCallbackOrderIsDefined(t *testing.T) {
d := New()
d.SOA(`*`, ReplyHandler("SOA 1"))
d.MX(`*`, ReplyHandler("MX 1"))
d.SOA(`*`, ReplyHandler("SOA 2"))
d.SOA(`*`, ReplyHandler("SOA 3"))
d.AAAA(`*`, ReplyHandler("AAAA 1"))
d.A(`*`, ReplyHandler("AAAA 2"))
rsp := AssertLookup(t, d, h.FakeQuery(1), 6, nil)
msg := "Order is wrong"
h.AssertEqualString(t, "SOA 1", rsp[0].Content, msg)
h.AssertEqualString(t, "SOA 2", rsp[1].Content, msg)
h.AssertEqualString(t, "SOA 3", rsp[2].Content, msg)
h.AssertEqualString(t, "MX 1", rsp[3].Content, msg)
h.AssertEqualString(t, "AAAA 1", rsp[4].Content, msg)
h.AssertEqualString(t, "AAAA 2", rsp[5].Content, msg)
}
func TestOnlyMatchingCallbacksAreRun(t *testing.T) {
d := New()
d.SOA(`example\.com`, ReplyHandler("Good"))
d.SOA(`example\.org`, ReplyHandler("Bad"))
rsp := AssertLookup(t, d, SOAQuery(), 1, nil)
h.AssertEqualString(t, "Good", rsp[0].Content, "Wrong callback run")
}
func TestOnlyCallbacksOfTheRightQTypeAreRun(t *testing.T) {
d := New()
d.SOA(`example\.com`, ReplyHandler("Good"))
d.NS(`example\.com`, ReplyHandler("Bad"))
rsp := AssertLookup(t, d, SOAQuery(), 1, nil)
h.AssertEqualString(t, "Good", rsp[0].Content, "Wrong callback run")
}
func TestCaptureGroupsArePutIntoContextMatches(t *testing.T) {
d := New()
var captures []string
d.SOA(`([a-z]{3})\.([a-z]{3})\.([a-z]{3})\.example\.com`, func(c *Context) {
captures = c.Matches
c.Reply("OK")
})
q := SOAQuery()
q.QName = "BAZ.bar.foo.example.com"
rsp := AssertLookup(t, d, q, 1, nil)
h.AssertEqualInt(t, 3, len(captures), "Wrong number of match groups returned")
h.AssertEqualString(t, "OK", rsp[0].Content, "Wrong callback run?")
// case-insensitive, so we don't mangle these
h.AssertEqualString(t, "BAZ", captures[0], "Part 1 not captured")
h.AssertEqualString(t, "bar", captures[1], "Part 2 not captured")
h.AssertEqualString(t, "foo", captures[2], "Part 3 not captured")
}
func TestBeforeCanModifyCaptureGroups(t *testing.T) {
d := New()
d.Before(func(c *Context) { c.Matches = append(c.Matches, "modify-cg") })
d.SOA(`*`, func(c *Context) { c.Reply(c.Matches[0]) })
rsp := AssertLookup(t, d, SOAQuery(), 1, nil)
h.AssertEqualString(t, "modify-cg", rsp[0].Content, "Capture modification lost")
}
func TestChangesToMatchesInOrdinaryCallbacksDoNotPersist(t *testing.T) {
d := New()
var ok bool
d.SOA(`*`, func(c *Context) { c.Matches = append(c.Matches, "Bad") })
d.SOA(`*`, func(c *Context) { ok = (len(c.Matches) == 0) })
AssertLookup(t, d, SOAQuery(), 0, nil)
h.Assert(t, ok, "Change was persisted")
}
func TestCallbackReturningErrorIsReported(t *testing.T) {
d := New()
d.SOA(`*`, ErrorReplyHandler)
AssertLookup(t, d, SOAQuery(), 0, ErrorReplyError)
}
func TestCallbackReturningErrorBlanksAnswers(t *testing.T) {
d := New()
d.SOA(`*`, ReplyHandler("Foo"))
d.SOA(`*`, ErrorReplyHandler)
AssertLookup(t, d, SOAQuery(), 0, ErrorReplyError)
}
func TestCallbackReturningErrorStopsLaterCallbacksFromRunning(t *testing.T) {
d := New()
ok := true
d.SOA(`*`, ErrorReplyHandler)
d.SOA(`*`, func(c *Context) { ok = false })
AssertLookup(t, d, SOAQuery(), 0, ErrorReplyError)
h.Assert(t, ok, "Later callback was run")
}

41
pipe/dsl/generate_dsl_helpers.sh Executable file
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@@ -0,0 +1,41 @@
#!/bin/sh
#
records=`curl -sf http://www.iana.org/assignments/dns-parameters/dns-parameters-4.csv | cut -f1 -d',' | sort | uniq | awk '/^[A-Z][A-Z]*$/ { print $0 }'` || exit 1
echo "// AUTOGENERATED helper methods for IANA-registered RRTYPES. Do not edit."
echo "// See generate_dsl_helpers.sh for details"
echo "package dsl"
echo "
import (
\"fmt\"
\"regexp\"
)
"
# A list of RRTypes might come in handy, you never know
echo "var RRTypes = []string{"
for record in $records; do
echo " \"${record}\","
done
echo "}"
for record in $records; do
echo "
// Helper function to register a callback for ${record} queries.
// The matcher is given as a string, which is compiled to a regular expression
// (using regexp.MustCompile) with the following rules:
//
// * The regexp is anchored to the start of the match string(\"^\" at start)
// * The case-insensitivity option is added \"(?i)\"
// * The regexp is anchored to the end of the match string (\"$\" at end)
//
// If any of these options are unwelcome, you can use the DSL.Register and pass
// a regexp and the \"${record}\" string directly.
func (d *DSL) ${record}(matcher string, f Callback) {
re := regexp.MustCompile(fmt.Sprintf(\"^(?i)%s$\", matcher))
d.Register(\"${record}\", re, f)
}"
done

98
pipe/test_helpers/test_helpers.go Normal file
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package test_helpers
import(
"fmt"
"github.com/BytemarkHosting/go-pdns/pipe/backend"
"testing"
)
func EmptyDispatch(b *backend.Backend, q *backend.Query)([]*backend.Response,error) {
return nil, nil
}
func AssertEqualString(t *testing.T, a, b, msg string) {
if a != b {
t.Logf(fmt.Sprintf("%s:'\n%s\n'\nshould be the same as:'\n%s\n'", msg, a, b))
t.FailNow()
}
}
func AssertEqualInt(t *testing.T, a, b int, msg string) {
if a != b {
t.Logf(fmt.Sprintf("%s: %d should == %d", msg, a, b))
t.FailNow()
}
}
func RefuteError(t *testing.T, err error, msg string) {
if err != nil {
t.Logf("Error: %s was expected to be nil", msg, err)
t.FailNow()
}
}
func Assert(t *testing.T, condition bool, msg string) {
if !condition {
t.Log(msg)
t.FailNow()
}
}
func FakeQuery(protoVersion int) *backend.Query {
if protoVersion < 1 || protoVersion > 3 {
panic("Invalid protoVersion")
}
q := backend.Query{
ProtocolVersion: protoVersion,
QClass: "IN",
QType: "ANY",
QName: "example.com",
Id: "-1",
RemoteIpAddress: "127.0.0.2",
}
if protoVersion > 1 {
q.LocalIpAddress = "127.0.0.1"
}
if protoVersion > 2 {
q.EdnsSubnetAddress = "127.0.0.3"
}
return &q
}
func FakeResponse(protoVersion int) *backend.Response {
if protoVersion < 1 || protoVersion > 3 {
panic("Invalid protoVersion")
}
r := backend.Response{
ProtocolVersion: protoVersion,
QClass: "IN",
QType: "ANY",
QName: "example.com",
Id: "-1",
TTL: "3600",
Content: "foo",
}
if protoVersion > 2 {
r.ScopeBits = "24"
r.Auth = "auth"
}
return &r
}
func FakeQueryString(t *testing.T, protoVersion int) string {
str, err := FakeQuery(protoVersion).String()
RefuteError(t, err, "Failed to serialise test query")
return str
}
func FakeResponseString(t *testing.T, protoVersion int) string {
str, err := FakeResponse(protoVersion).String()
RefuteError(t, err, "Failed to serialise test response")
return str
}