mirror of
https://github.com/miekg/dns.git
synced 2025-10-10 17:31:01 +02:00
874787c537
Implemented in both the server and client. Renamed to client function to match the server side functions Example progs need to be "ported" as this *is* an API change.
508 lines
13 KiB
Go
508 lines
13 KiB
Go
package dns
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// A concurrent client implementation.
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// Client sends query to a channel which
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// will then handle the query. Returned replys
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// are return on another channel. Ready for handling --- same
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// setup for server - a HANDLER function that gets run
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// when the query returns.
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import (
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"io"
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"net"
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"time"
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)
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// Check incoming TSIG message. TODO(mg)
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// Need a tsigstatus for that too? Don't know yet. TODO(mg)
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// Incoming (just as in os.Signal)
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type QueryHandler interface {
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QueryDNS(w RequestWriter, q *Msg)
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}
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// The RequestWriter interface is used by a DNS query handler to
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// construct a DNS request.
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type RequestWriter interface {
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// Write returns the request message and the reply back to the client.
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Write(*Msg) error
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// Send sends the message to the server.
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Send(*Msg) error
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// Receive waits for the reply of the servers.
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Receive() (*Msg, error)
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// Close closes the connection with the server.
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Close() error
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// Dials calls the server
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Dial() error
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// TsigStatus return the TSIG validation status.
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TsigStatus() error
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}
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// hijacked connections...?
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type reply struct {
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client *Client
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addr string
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req *Msg
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conn net.Conn
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tsigRequestMAC string
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tsigTimersOnly bool
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tsigStatus error
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}
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// A Request is a incoming message from a Client.
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type Request struct {
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Request *Msg
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Addr string
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Client *Client
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}
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// QueryMux is an DNS request multiplexer. It matches the
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// zone name of each incoming request against a list of
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// registered patterns add calls the handler for the pattern
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// that most closely matches the zone name.
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type QueryMux struct {
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m map[string]QueryHandler
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}
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// NewQueryMux allocates and returns a new QueryMux.
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func NewQueryMux() *QueryMux { return &QueryMux{make(map[string]QueryHandler)} }
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// DefaultQueryMux is the default QueryMux used by Query.
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var DefaultQueryMux = NewQueryMux()
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func newQueryChanSlice() chan *Exchange { return make(chan *Exchange) }
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func newQueryChan() chan *Request { return make(chan *Request) }
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// Default channels to use for the resolver
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var (
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// DefaultReplyChan is the channel on which the replies are
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// coming back. Is it a channel of *Exchange, so that the original
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// question is included with the answer.
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DefaultReplyChan = newQueryChanSlice()
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// DefaultQueryChan is the channel were you can send the questions to.
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DefaultQueryChan = newQueryChan()
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)
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// The HandlerQueryFunc type is an adapter to allow the use of
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// ordinary functions as DNS query handlers. If f is a function
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// with the appropriate signature, HandlerQueryFunc(f) is a
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// QueryHandler object that calls f.
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type HandlerQueryFunc func(RequestWriter, *Msg)
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// QueryDNS calls f(w, reg)
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func (f HandlerQueryFunc) QueryDNS(w RequestWriter, r *Msg) {
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go f(w, r)
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}
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// HandleQueryFunc registers the handler with the given pattern in the
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// DefaultQueryMux.
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func HandleQueryFunc(pattern string, handler func(RequestWriter, *Msg)) {
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DefaultQueryMux.HandleFunc(pattern, handler)
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}
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// HandleQuery registers the handler
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// in the DefaultQueryMux
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func HandleQuery(pattern string, handler HandlerQueryFunc) {
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DefaultQueryMux.Handle(pattern, handler)
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}
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// HandleQueryRemove deregisters the handle with the given pattern
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// in the DefaultQueryMux.
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func HandleQueryRemove(pattern string) {
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DefaultQueryMux.HandleRemove(pattern)
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}
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// reusing zoneMatch from server.go
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func (mux *QueryMux) match(zone string) QueryHandler {
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var h QueryHandler
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var n = 0
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for k, v := range mux.m {
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if !zoneMatch(k, zone) {
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continue
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}
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if h == nil || len(k) > n {
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n = len(k)
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h = v
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}
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}
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return h
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}
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func (mux *QueryMux) Handle(pattern string, handler QueryHandler) {
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if pattern == "" {
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panic("dns: invalid pattern " + pattern)
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}
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mux.m[pattern] = handler
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}
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// HandleRemove deregisters the handler with given pattern.
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func (mux *QueryMux) HandleRemove(pattern string) {
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delete(mux.m, pattern)
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}
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// HandleFunc ...
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func (mux *QueryMux) HandleFunc(pattern string, handler func(RequestWriter, *Msg)) {
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mux.Handle(pattern, HandlerQueryFunc(handler))
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}
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func (mux *QueryMux) QueryDNS(w RequestWriter, r *Msg) {
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h := mux.match(r.Question[0].Name)
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if h == nil {
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panic("dns: no handler found for " + r.Question[0].Name)
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}
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h.QueryDNS(w, r)
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}
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type Client struct {
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Net string // if "tcp" a TCP query will be initiated, otherwise an UDP one
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Attempts int // number of attempts
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Retry bool // retry with TCP
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QueryChan chan *Request // read DNS request from this channel
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ReplyChan chan *Exchange // write the reply (together with the DNS request) to this channel
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ReadTimeout time.Duration // the net.Conn.SetReadTimeout value for new connections (ns)
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WriteTimeout time.Duration // the net.Conn.SetWriteTimeout value for new connections (ns)
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TsigSecret map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>
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Hijacked net.Conn // if set the calling code takes care of the connection
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// LocalAddr string // Local address to use
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}
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// NewClient creates a new client, with Net set to "udp" and Attempts to 1.
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// The client's ReplyChan is set to DefaultReplyChan and QueryChan
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// to DefaultQueryChan.
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func NewClient() *Client {
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c := new(Client)
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c.Net = "udp"
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c.Attempts = 1
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c.ReplyChan = DefaultReplyChan
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c.QueryChan = DefaultQueryChan
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c.ReadTimeout = 2 * 1e9
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c.WriteTimeout = 2 * 1e9
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return c
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}
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type Query struct {
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QueryChan chan *Request // read DNS request from this channel
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Handler QueryHandler // handler to invoke, dns.DefaultQueryMux if nil
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}
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func (q *Query) Query() error {
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handler := q.Handler
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if handler == nil {
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handler = DefaultQueryMux
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}
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//forever:
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for {
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select {
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case in := <-q.QueryChan:
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w := new(reply)
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w.req = in.Request
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w.addr = in.Addr
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w.client = in.Client
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handler.QueryDNS(w, in.Request)
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}
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}
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return nil
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}
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func (q *Query) ListenAndQuery() error {
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if q.QueryChan == nil {
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q.QueryChan = DefaultQueryChan
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}
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return q.Query()
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}
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// ListenAndQuery starts the listener for firing off the queries. If
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// c is nil DefaultQueryChan is used. If handler is nil
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// DefaultQueryMux is used.
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func ListenAndQuery(request chan *Request, handler QueryHandler) {
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q := &Query{QueryChan: request, Handler: handler}
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go q.ListenAndQuery()
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}
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// Write returns the original question and the answer on the
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// reply channel of the client.
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func (w *reply) Write(m *Msg) error {
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w.Client().ReplyChan <- &Exchange{Request: w.req, Reply: m}
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return nil
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}
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// Do performs an asynchronous query. The result is returned on the
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// QueryChan channel set in the Client c.
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func (c *Client) Do(m *Msg, a string) {
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c.QueryChan <- &Request{Client: c, Addr: a, Request: m}
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}
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// ExchangeBuffer performs a synchronous query. It sends the buffer m to the
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// address contained in a.
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func (c *Client) ExchangeBuffer(inbuf []byte, a string, outbuf []byte) (n int, err error) {
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w := new(reply)
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w.client = c
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w.addr = a
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if c.Hijacked == nil {
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if err = w.Dial(); err != nil {
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return 0, err
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}
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defer w.Close()
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}
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if c.Hijacked != nil {
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w.conn = c.Hijacked
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}
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if n, err = w.writeClient(inbuf); err != nil {
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return 0, err
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}
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if n, err = w.readClient(outbuf); err != nil {
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return n, err
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}
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return n, nil
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}
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// Exchange performs an synchronous query. It sends the message m to the address
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// contained in a and waits for an reply.
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func (c *Client) Exchange(m *Msg, a string) (r *Msg, err error) {
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var n int
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out, ok := m.Pack()
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if !ok {
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return nil, ErrPack
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}
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var in []byte
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switch c.Net {
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case "tcp":
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in = make([]byte, MaxMsgSize)
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case "udp":
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size := UDPMsgSize
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for _, r := range m.Extra {
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if r.Header().Rrtype == TypeOPT {
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size = int(r.(*RR_OPT).UDPSize())
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}
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}
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in = make([]byte, size)
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}
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if n, err = c.ExchangeBuffer(out, a, in); err != nil {
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return nil, err
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}
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r = new(Msg)
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if ok := r.Unpack(in[:n]); !ok {
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return nil, ErrUnpack
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}
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return r, nil
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}
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// Dial connects to the address addr for the network set in c.Net
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func (w *reply) Dial() error {
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conn, err := net.Dial(w.Client().Net, w.addr)
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if err != nil {
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return err
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}
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w.conn = conn
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return nil
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}
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func (w *reply) Close() (err error) {
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return w.conn.Close()
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}
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func (w *reply) Client() *Client {
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return w.client
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}
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func (w *reply) Request() *Msg {
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return w.req
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}
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func (w *reply) TsigStatus() error {
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return w.tsigStatus
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}
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func (w *reply) Receive() (*Msg, error) {
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var p []byte
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m := new(Msg)
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switch w.Client().Net {
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case "tcp", "tcp4", "tcp6":
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p = make([]byte, MaxMsgSize)
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case "udp", "udp4", "udp6":
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p = make([]byte, DefaultMsgSize)
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}
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n, err := w.readClient(p)
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if err != nil {
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return nil, err
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}
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p = p[:n]
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if ok := m.Unpack(p); !ok {
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return nil, ErrUnpack
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}
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if m.IsTsig() {
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secret := m.Extra[len(m.Extra)-1].(*RR_TSIG).Hdr.Name
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if _, ok := w.Client().TsigSecret[secret]; !ok {
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w.tsigStatus = ErrSecret
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return m, nil
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}
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// Need to work on the original message p, as that was used to calculate the tsig.
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w.tsigStatus = TsigVerify(p, w.Client().TsigSecret[secret], w.tsigRequestMAC, w.tsigTimersOnly)
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}
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return m, nil
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}
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func (w *reply) readClient(p []byte) (n int, err error) {
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if w.conn == nil {
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return 0, ErrConnEmpty
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}
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switch w.Client().Net {
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case "tcp", "tcp4", "tcp6":
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if len(p) < 1 {
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return 0, io.ErrShortBuffer
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}
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for a := 0; a < w.Client().Attempts; a++ {
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w.conn.SetReadDeadline(time.Now().Add(w.Client().ReadTimeout))
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w.conn.SetWriteDeadline(time.Now().Add(w.Client().WriteTimeout))
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n, err = w.conn.(*net.TCPConn).Read(p[0:2])
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if err != nil || n != 2 {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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continue
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}
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return n, err
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}
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l, _ := unpackUint16(p[0:2], 0)
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if l == 0 {
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return 0, ErrShortRead
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}
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if int(l) > len(p) {
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return int(l), io.ErrShortBuffer
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}
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n, err = w.conn.(*net.TCPConn).Read(p[:l])
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if err != nil {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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continue
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}
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return n, err
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}
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i := n
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for i < int(l) {
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j, err := w.conn.(*net.TCPConn).Read(p[i:int(l)])
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if err != nil {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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// We are half way in our read...
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continue
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}
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return i, err
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}
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i += j
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}
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n = i
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}
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case "udp", "udp4", "udp6":
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for a := 0; a < w.Client().Attempts; a++ {
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w.conn.SetReadDeadline(time.Now().Add(w.Client().ReadTimeout))
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w.conn.SetWriteDeadline(time.Now().Add(w.Client().ReadTimeout))
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n, _, err = w.conn.(*net.UDPConn).ReadFromUDP(p)
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if err != nil {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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continue
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}
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return n, err
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}
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}
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}
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return
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}
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// Send sends a dns msg to the address specified in w.
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// If the message m contains a TSIG record the transaction
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// signature is calculated.
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func (w *reply) Send(m *Msg) (err error) {
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var out []byte
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if m.IsTsig() {
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mac := ""
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name := m.Extra[len(m.Extra)-1].(*RR_TSIG).Hdr.Name
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if _, ok := w.Client().TsigSecret[name]; !ok {
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return ErrSecret
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}
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out, mac, err = TsigGenerate(m, w.Client().TsigSecret[name], w.tsigRequestMAC, w.tsigTimersOnly)
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if err != nil {
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return err
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}
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w.tsigRequestMAC = mac
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} else {
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ok := false
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out, ok = m.Pack()
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if !ok {
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return ErrPack
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}
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}
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if _, err = w.writeClient(out); err != nil {
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return err
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}
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return nil
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}
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func (w *reply) writeClient(p []byte) (n int, err error) {
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if w.Client().Attempts == 0 {
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panic("c.Attempts 0")
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}
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if w.Client().Net == "" {
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panic("c.Net empty")
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}
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if w.Client().Hijacked == nil {
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if err = w.Dial(); err != nil {
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return 0, err
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}
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}
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switch w.Client().Net {
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case "tcp", "tcp4", "tcp6":
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if len(p) < 2 {
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return 0, io.ErrShortBuffer
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}
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for a := 0; a < w.Client().Attempts; a++ {
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w.conn.SetWriteDeadline(time.Now().Add(w.Client().WriteTimeout))
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w.conn.SetReadDeadline(time.Now().Add(w.Client().ReadTimeout))
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a, b := packUint16(uint16(len(p)))
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n, err = w.conn.Write([]byte{a, b})
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if err != nil {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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continue
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}
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return n, err
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}
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if n != 2 {
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return n, io.ErrShortWrite
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}
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n, err = w.conn.Write(p)
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if err != nil {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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continue
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}
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return n, err
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}
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i := n
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if i < len(p) {
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j, err := w.conn.Write(p[i:len(p)])
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if err != nil {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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// We are half way in our write...
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continue
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}
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return i, err
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}
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i += j
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}
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n = i
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}
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case "udp", "udp4", "udp6":
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for a := 0; a < w.Client().Attempts; a++ {
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w.conn.SetWriteDeadline(time.Now().Add(w.Client().WriteTimeout))
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w.conn.SetReadDeadline(time.Now().Add(w.Client().ReadTimeout))
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n, err = w.conn.(*net.UDPConn).Write(p)
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if err != nil {
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if e, ok := err.(net.Error); ok && e.Timeout() {
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continue
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}
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return n, err
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}
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}
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}
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return
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}
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