Export dns.Conn and make it more like net.Conn
Export lowlevel function and types so that they may be used. They higher level Exchange function is still there. ExchangeConn is gone, because it is not needed.
This commit is contained in:
Miek Gieben
parent
22977491c3
commit
4bde528be5
213
client.go
213
client.go
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@ -12,17 +12,9 @@ import (
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"time"
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)
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// Order of events:
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// *client -> *reply -> Exchange() -> dial()/send()->write()/receive()->read()
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// A Conn represents a connection (which may be short lived) to a DNS
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// server.
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// A Conn represents a connection (which may be short lived) to a DNS server.
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type Conn struct {
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net.Conn
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client *Client
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addr string
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req *Msg
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tsigRequestMAC string
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tsigTimersOnly bool
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tsigStatus error
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@ -30,8 +22,7 @@ type Conn struct {
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t time.Time
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}
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// A Client defines parameter for a DNS client. A nil
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// Client is usable for sending queries.
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// A Client defines parameters for a DNS client. A nil Client is usable for sending queries.
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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 (default is "" for UDP)
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ReadTimeout time.Duration // the net.Conn.SetReadTimeout value for new connections (ns), defaults to 2 * 1e9
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@ -41,16 +32,31 @@ type Client struct {
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group singleflight
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}
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func Exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err) {
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// Exchange performs an synchronous UDP 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 Exchange(m *Msg, a string) (r *Msg, err error) {
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co := new(Conn)
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co.Conn, err = net.DialTimeout("udp", a, 5*1e9)
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if err != nil {
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return nil, err
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}
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defer co.Close()
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if err = co.WriteMsg(m); err != nil {
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return nil, err
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}
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r, err = co.ReadMsg()
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return r, err
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}
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func (c *Client) exchangeMerge(m *Msg, a string, s net.Conn) (r *Msg, rtt time.Duration, err error) {
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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. Basic use pattern with a *dns.Client:
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//
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// c := new(dns.Client)
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// in, rtt, err := c.Exchange(message, "127.0.0.1:53")
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//
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func (c *Client) Exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
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if !c.SingleInflight {
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if s == nil {
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return c.exchange(m, a)
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}
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return c.exchangeConn(m, s)
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return c.exchange(m, a)
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}
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// This adds a bunch of garbage, TODO(miek).
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t := "nop"
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@ -62,86 +68,47 @@ func (c *Client) exchangeMerge(m *Msg, a string, s net.Conn) (r *Msg, rtt time.D
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cl = cl1
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}
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r, rtt, err, shared := c.group.Do(m.Question[0].Name+t+cl, func() (*Msg, time.Duration, error) {
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if s == nil {
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return c.exchange(m, a)
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}
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return c.exchangeConn(m, s)
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return c.exchange(m, a)
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})
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if err != nil {
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return r, rtt, err
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}
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if shared {
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r1 := r.copy()
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r1.Id = r.Id // Copy Id!
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// not needed r1.Id = r.Id // Copy Id!
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r = r1
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}
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return r, rtt, 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. Basic use pattern with a *dns.Client:
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//
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// c := new(dns.Client)
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// in, rtt, err := c.Exchange(message, "127.0.0.1:53")
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//
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func (c *Client) Exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
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return c.exchangeMerge(m, a, nil)
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}
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func (c *Client) exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
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w := &reply{client: c, addr: a}
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if err = w.dial(); err != nil {
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return nil, 0, err
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}
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defer w.conn.Close()
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if err = w.send(m); err != nil {
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return nil, 0, err
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}
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r, err = w.receive()
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return r, w.rtt, err
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}
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// ExchangeConn performs an synchronous query. It sends the message m trough the
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// connection s and waits for a reply.
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func (c *Client) ExchangeConn(m *Msg, s net.Conn) (r *Msg, rtt time.Duration, err error) {
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return c.exchangeMerge(m, "", s)
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}
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func (c *Client) exchangeConn(m *Msg, s net.Conn) (r *Msg, rtt time.Duration, err error) {
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w := &reply{client: c, conn: s}
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if err = w.send(m); err != nil {
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return nil, 0, err
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}
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r, err = w.receive()
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return r, w.rtt, err
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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() (err error) {
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var conn net.Conn
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if w.client.Net == "" {
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conn, err = net.DialTimeout("udp", w.addr, 5*1e9)
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co := new(Conn)
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if c.Net == "" {
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co.Conn, err = net.DialTimeout("udp", a, 5*1e9)
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} else {
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conn, err = net.DialTimeout(w.client.Net, w.addr, 5*1e9)
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co.Conn, err = net.DialTimeout(c.Net, a, 5*1e9)
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}
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if err != nil {
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return err
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return nil, 0, err
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}
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w.conn = conn
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return
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defer co.Close()
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if err = co.WriteMsg(m); err != nil {
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return nil, 0, err
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}
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r, err = co.ReadMsg()
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return r, co.rtt, err
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}
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func (w *reply) receive() (*Msg, error) {
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func (co *Conn) ReadMsg() (*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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if _, ok := co.Conn.(*net.TCPConn); ok {
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p = make([]byte, MaxMsgSize)
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case "", "udp", "udp4", "udp6":
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} else {
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// OPT! TODO(mg)
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p = make([]byte, DefaultMsgSize)
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}
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n, err := w.read(p)
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n, err := co.Read(p)
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if err != nil && n == 0 {
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return nil, err
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}
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@ -149,30 +116,28 @@ func (w *reply) receive() (*Msg, error) {
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if err := m.Unpack(p); err != nil {
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return nil, err
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}
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w.rtt = time.Since(w.t)
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if t := m.IsTsig(); t != nil {
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secret := t.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, ErrSecret
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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, w.tsigStatus
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co.rtt = time.Since(co.t)
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// if t := m.IsTsig(); t != nil {
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// secret := t.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, ErrSecret
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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) read(p []byte) (n int, err error) {
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if w.conn == nil {
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func (co *Conn) Read(p []byte) (n int, err error) {
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if co.Conn == nil {
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return 0, ErrConnEmpty
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}
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if len(p) < 2 {
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return 0, io.ErrShortBuffer
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}
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switch w.client.Net {
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case "tcp", "tcp4", "tcp6":
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setTimeouts(w)
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n, err = w.conn.(*net.TCPConn).Read(p[0:2])
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if t, ok := co.Conn.(*net.TCPConn); ok {
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n, err = t.Read(p[0:2])
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if err != nil || n != 2 {
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return n, err
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}
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@ -183,25 +148,25 @@ func (w *reply) read(p []byte) (n int, err error) {
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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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n, err = t.Read(p[:l])
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if err != nil {
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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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j, err := t.Read(p[i:int(l)])
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if err != nil {
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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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case "", "udp", "udp4", "udp6":
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setTimeouts(w)
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n, _, err = w.conn.(*net.UDPConn).ReadFromUDP(p)
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if err != nil {
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return n, err
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}
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return n, err
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}
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// assume udp connection
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n, _, err = co.Conn.(*net.UDPConn).ReadFromUDP(p)
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if err != nil {
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return n, err
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}
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return n, err
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}
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@ -209,62 +174,57 @@ func (w *reply) read(p []byte) (n int, err error) {
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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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func (co *Conn) WriteMsg(m *Msg) (err error) {
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var out []byte
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if t := m.IsTsig(); t != nil {
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mac := ""
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name := t.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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w.tsigRequestMAC = mac
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} else {
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out, err = m.Pack()
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}
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// if t := m.IsTsig(); t != nil {
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// mac := ""
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// name := t.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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// w.tsigRequestMAC = mac
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// } else {
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out, err = m.Pack()
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// }
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if err != nil {
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return err
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}
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w.t = time.Now()
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if _, err = w.write(out); err != nil {
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co.t = time.Now()
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if _, err = co.Write(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) write(p []byte) (n int, err error) {
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switch w.client.Net {
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case "tcp", "tcp4", "tcp6":
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func (co *Conn) Write(p []byte) (n int, err error) {
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if t, ok := co.Conn.(*net.TCPConn); ok {
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if len(p) < 2 {
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return 0, io.ErrShortBuffer
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}
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setTimeouts(w)
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l := make([]byte, 2)
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l[0], l[1] = packUint16(uint16(len(p)))
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p = append(l, p...)
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n, err := w.conn.Write(p)
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n, err := t.Write(p)
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if err != nil {
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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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j, err := t.Write(p[i:len(p)])
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if err != nil {
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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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case "", "udp", "udp4", "udp6":
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setTimeouts(w)
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n, err = w.conn.(*net.UDPConn).Write(p)
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if err != nil {
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return n, err
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}
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return n, err
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}
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return
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n, err = co.Conn.(*net.UDPConn).Write(p)
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return n, err
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}
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/*
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func setTimeouts(w *reply) {
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if w.client.ReadTimeout == 0 {
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w.conn.SetReadDeadline(time.Now().Add(2 * 1e9))
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@ -278,3 +238,4 @@ func setTimeouts(w *reply) {
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w.conn.SetWriteDeadline(time.Now().Add(w.client.WriteTimeout))
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}
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}
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*/
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@ -396,6 +396,7 @@ func shortRR(r dns.RR) dns.RR {
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}
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func doXfr(c *dns.Client, m *dns.Msg, nameserver string) {
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/*
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if t, e := c.TransferIn(m, nameserver); e == nil {
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for r := range t {
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if r.Error == nil {
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@ -412,4 +413,5 @@ func doXfr(c *dns.Client, m *dns.Msg, nameserver string) {
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} else {
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fmt.Fprintf(os.Stderr, "Failure to read XFR: %s\n", e.Error())
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}
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*/
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}
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2
xfr.go
2
xfr.go
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@ -10,6 +10,7 @@ type Envelope struct {
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Error error // If something went wrong, this contains the error.
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}
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/*
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// TransferIn performs a [AI]XFR request (depends on the message's Qtype). It returns
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// a channel of *Envelope on which the replies from the server are sent. At the end of
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// the transfer the channel is closed.
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@ -201,3 +202,4 @@ func xfrOut(w ResponseWriter, req *Msg, c chan *Envelope, e *error) {
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rep.Answer = nil
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}
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}
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*/
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