diff options
Diffstat (limited to 'vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/client.go')
| -rw-r--r-- | vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/client.go | 467 |
1 files changed, 467 insertions, 0 deletions
diff --git a/vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/client.go b/vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/client.go new file mode 100644 index 000000000..301dab9c1 --- /dev/null +++ b/vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/client.go @@ -0,0 +1,467 @@ +package dns + +// A client implementation. + +import ( + "bytes" + "crypto/tls" + "encoding/binary" + "io" + "net" + "time" +) + +const dnsTimeout time.Duration = 2 * time.Second +const tcpIdleTimeout time.Duration = 8 * time.Second + +// A Conn represents a connection to a DNS server. +type Conn struct { + net.Conn // a net.Conn holding the connection + UDPSize uint16 // minimum receive buffer for UDP messages + TsigSecret map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be fully qualified + rtt time.Duration + t time.Time + tsigRequestMAC string +} + +// A Client defines parameters for a DNS client. +type Client struct { + Net string // if "tcp" or "tcp-tls" (DNS over TLS) a TCP query will be initiated, otherwise an UDP one (default is "" for UDP) + UDPSize uint16 // minimum receive buffer for UDP messages + TLSConfig *tls.Config // TLS connection configuration + Timeout time.Duration // a cumulative timeout for dial, write and read, defaults to 0 (disabled) - overrides DialTimeout, ReadTimeout and WriteTimeout when non-zero + DialTimeout time.Duration // net.DialTimeout, defaults to 2 seconds - overridden by Timeout when that value is non-zero + ReadTimeout time.Duration // net.Conn.SetReadTimeout value for connections, defaults to 2 seconds - overridden by Timeout when that value is non-zero + WriteTimeout time.Duration // net.Conn.SetWriteTimeout value for connections, defaults to 2 seconds - overridden by Timeout when that value is non-zero + TsigSecret map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be fully qualified + SingleInflight bool // if true suppress multiple outstanding queries for the same Qname, Qtype and Qclass + group singleflight +} + +// Exchange performs a synchronous UDP query. It sends the message m to the address +// contained in a and waits for a reply. Exchange does not retry a failed query, nor +// will it fall back to TCP in case of truncation. +// See client.Exchange for more information on setting larger buffer sizes. +func Exchange(m *Msg, a string) (r *Msg, err error) { + var co *Conn + co, err = DialTimeout("udp", a, dnsTimeout) + if err != nil { + return nil, err + } + + defer co.Close() + + opt := m.IsEdns0() + // If EDNS0 is used use that for size. + if opt != nil && opt.UDPSize() >= MinMsgSize { + co.UDPSize = opt.UDPSize() + } + + co.SetWriteDeadline(time.Now().Add(dnsTimeout)) + if err = co.WriteMsg(m); err != nil { + return nil, err + } + + co.SetReadDeadline(time.Now().Add(dnsTimeout)) + r, err = co.ReadMsg() + if err == nil && r.Id != m.Id { + err = ErrId + } + return r, err +} + +// ExchangeConn performs a synchronous query. It sends the message m via the connection +// c and waits for a reply. The connection c is not closed by ExchangeConn. +// This function is going away, but can easily be mimicked: +// +// co := &dns.Conn{Conn: c} // c is your net.Conn +// co.WriteMsg(m) +// in, _ := co.ReadMsg() +// co.Close() +// +func ExchangeConn(c net.Conn, m *Msg) (r *Msg, err error) { + println("dns: this function is deprecated") + co := new(Conn) + co.Conn = c + if err = co.WriteMsg(m); err != nil { + return nil, err + } + r, err = co.ReadMsg() + if err == nil && r.Id != m.Id { + err = ErrId + } + return r, err +} + +// Exchange performs a synchronous query. It sends the message m to the address +// contained in a and waits for a reply. Basic use pattern with a *dns.Client: +// +// c := new(dns.Client) +// in, rtt, err := c.Exchange(message, "127.0.0.1:53") +// +// Exchange does not retry a failed query, nor will it fall back to TCP in +// case of truncation. +// It is up to the caller to create a message that allows for larger responses to be +// returned. Specifically this means adding an EDNS0 OPT RR that will advertise a larger +// buffer, see SetEdns0. Messages without an OPT RR will fallback to the historic limit +// of 512 bytes. +func (c *Client) Exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err error) { + if !c.SingleInflight { + return c.exchange(m, a) + } + // This adds a bunch of garbage, TODO(miek). + t := "nop" + if t1, ok := TypeToString[m.Question[0].Qtype]; ok { + t = t1 + } + cl := "nop" + if cl1, ok := ClassToString[m.Question[0].Qclass]; ok { + cl = cl1 + } + r, rtt, err, shared := c.group.Do(m.Question[0].Name+t+cl, func() (*Msg, time.Duration, error) { + return c.exchange(m, a) + }) + if r != nil && shared { + r = r.Copy() + } + if err != nil { + return r, rtt, err + } + return r, rtt, nil +} + +func (c *Client) dialTimeout() time.Duration { + if c.Timeout != 0 { + return c.Timeout + } + if c.DialTimeout != 0 { + return c.DialTimeout + } + return dnsTimeout +} + +func (c *Client) readTimeout() time.Duration { + if c.ReadTimeout != 0 { + return c.ReadTimeout + } + return dnsTimeout +} + +func (c *Client) writeTimeout() time.Duration { + if c.WriteTimeout != 0 { + return c.WriteTimeout + } + return dnsTimeout +} + +func (c *Client) exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err error) { + var co *Conn + network := "udp" + tls := false + + switch c.Net { + case "tcp-tls": + network = "tcp" + tls = true + case "tcp4-tls": + network = "tcp4" + tls = true + case "tcp6-tls": + network = "tcp6" + tls = true + default: + if c.Net != "" { + network = c.Net + } + } + + var deadline time.Time + if c.Timeout != 0 { + deadline = time.Now().Add(c.Timeout) + } + + if tls { + co, err = DialTimeoutWithTLS(network, a, c.TLSConfig, c.dialTimeout()) + } else { + co, err = DialTimeout(network, a, c.dialTimeout()) + } + + if err != nil { + return nil, 0, err + } + defer co.Close() + + opt := m.IsEdns0() + // If EDNS0 is used use that for size. + if opt != nil && opt.UDPSize() >= MinMsgSize { + co.UDPSize = opt.UDPSize() + } + // Otherwise use the client's configured UDP size. + if opt == nil && c.UDPSize >= MinMsgSize { + co.UDPSize = c.UDPSize + } + + co.TsigSecret = c.TsigSecret + co.SetWriteDeadline(deadlineOrTimeout(deadline, c.writeTimeout())) + if err = co.WriteMsg(m); err != nil { + return nil, 0, err + } + + co.SetReadDeadline(deadlineOrTimeout(deadline, c.readTimeout())) + r, err = co.ReadMsg() + if err == nil && r.Id != m.Id { + err = ErrId + } + return r, co.rtt, err +} + +// ReadMsg reads a message from the connection co. +// If the received message contains a TSIG record the transaction +// signature is verified. +func (co *Conn) ReadMsg() (*Msg, error) { + p, err := co.ReadMsgHeader(nil) + if err != nil { + return nil, err + } + + m := new(Msg) + if err := m.Unpack(p); err != nil { + // If ErrTruncated was returned, we still want to allow the user to use + // the message, but naively they can just check err if they don't want + // to use a truncated message + if err == ErrTruncated { + return m, err + } + return nil, err + } + if t := m.IsTsig(); t != nil { + if _, ok := co.TsigSecret[t.Hdr.Name]; !ok { + return m, ErrSecret + } + // Need to work on the original message p, as that was used to calculate the tsig. + err = TsigVerify(p, co.TsigSecret[t.Hdr.Name], co.tsigRequestMAC, false) + } + return m, err +} + +// ReadMsgHeader reads a DNS message, parses and populates hdr (when hdr is not nil). +// Returns message as a byte slice to be parsed with Msg.Unpack later on. +// Note that error handling on the message body is not possible as only the header is parsed. +func (co *Conn) ReadMsgHeader(hdr *Header) ([]byte, error) { + var ( + p []byte + n int + err error + ) + + switch t := co.Conn.(type) { + case *net.TCPConn, *tls.Conn: + r := t.(io.Reader) + + // First two bytes specify the length of the entire message. + l, err := tcpMsgLen(r) + if err != nil { + return nil, err + } + p = make([]byte, l) + n, err = tcpRead(r, p) + co.rtt = time.Since(co.t) + default: + if co.UDPSize > MinMsgSize { + p = make([]byte, co.UDPSize) + } else { + p = make([]byte, MinMsgSize) + } + n, err = co.Read(p) + co.rtt = time.Since(co.t) + } + + if err != nil { + return nil, err + } else if n < headerSize { + return nil, ErrShortRead + } + + p = p[:n] + if hdr != nil { + dh, _, err := unpackMsgHdr(p, 0) + if err != nil { + return nil, err + } + *hdr = dh + } + return p, err +} + +// tcpMsgLen is a helper func to read first two bytes of stream as uint16 packet length. +func tcpMsgLen(t io.Reader) (int, error) { + p := []byte{0, 0} + n, err := t.Read(p) + if err != nil { + return 0, err + } + + // As seen with my local router/switch, retursn 1 byte on the above read, + // resulting a a ShortRead. Just write it out (instead of loop) and read the + // other byte. + if n == 1 { + n1, err := t.Read(p[1:]) + if err != nil { + return 0, err + } + n += n1 + } + + if n != 2 { + return 0, ErrShortRead + } + l := binary.BigEndian.Uint16(p) + if l == 0 { + return 0, ErrShortRead + } + return int(l), nil +} + +// tcpRead calls TCPConn.Read enough times to fill allocated buffer. +func tcpRead(t io.Reader, p []byte) (int, error) { + n, err := t.Read(p) + if err != nil { + return n, err + } + for n < len(p) { + j, err := t.Read(p[n:]) + if err != nil { + return n, err + } + n += j + } + return n, err +} + +// Read implements the net.Conn read method. +func (co *Conn) Read(p []byte) (n int, err error) { + if co.Conn == nil { + return 0, ErrConnEmpty + } + if len(p) < 2 { + return 0, io.ErrShortBuffer + } + switch t := co.Conn.(type) { + case *net.TCPConn, *tls.Conn: + r := t.(io.Reader) + + l, err := tcpMsgLen(r) + if err != nil { + return 0, err + } + if l > len(p) { + return int(l), io.ErrShortBuffer + } + return tcpRead(r, p[:l]) + } + // UDP connection + n, err = co.Conn.Read(p) + if err != nil { + return n, err + } + return n, err +} + +// WriteMsg sends a message through the connection co. +// If the message m contains a TSIG record the transaction +// signature is calculated. +func (co *Conn) WriteMsg(m *Msg) (err error) { + var out []byte + if t := m.IsTsig(); t != nil { + mac := "" + if _, ok := co.TsigSecret[t.Hdr.Name]; !ok { + return ErrSecret + } + out, mac, err = TsigGenerate(m, co.TsigSecret[t.Hdr.Name], co.tsigRequestMAC, false) + // Set for the next read, although only used in zone transfers + co.tsigRequestMAC = mac + } else { + out, err = m.Pack() + } + if err != nil { + return err + } + co.t = time.Now() + if _, err = co.Write(out); err != nil { + return err + } + return nil +} + +// Write implements the net.Conn Write method. +func (co *Conn) Write(p []byte) (n int, err error) { + switch t := co.Conn.(type) { + case *net.TCPConn, *tls.Conn: + w := t.(io.Writer) + + lp := len(p) + if lp < 2 { + return 0, io.ErrShortBuffer + } + if lp > MaxMsgSize { + return 0, &Error{err: "message too large"} + } + l := make([]byte, 2, lp+2) + binary.BigEndian.PutUint16(l, uint16(lp)) + p = append(l, p...) + n, err := io.Copy(w, bytes.NewReader(p)) + return int(n), err + } + n, err = co.Conn.Write(p) + return n, err +} + +// Dial connects to the address on the named network. +func Dial(network, address string) (conn *Conn, err error) { + conn = new(Conn) + conn.Conn, err = net.Dial(network, address) + if err != nil { + return nil, err + } + return conn, nil +} + +// DialTimeout acts like Dial but takes a timeout. +func DialTimeout(network, address string, timeout time.Duration) (conn *Conn, err error) { + conn = new(Conn) + conn.Conn, err = net.DialTimeout(network, address, timeout) + if err != nil { + return nil, err + } + return conn, nil +} + +// DialWithTLS connects to the address on the named network with TLS. +func DialWithTLS(network, address string, tlsConfig *tls.Config) (conn *Conn, err error) { + conn = new(Conn) + conn.Conn, err = tls.Dial(network, address, tlsConfig) + if err != nil { + return nil, err + } + return conn, nil +} + +// DialTimeoutWithTLS acts like DialWithTLS but takes a timeout. +func DialTimeoutWithTLS(network, address string, tlsConfig *tls.Config, timeout time.Duration) (conn *Conn, err error) { + var dialer net.Dialer + dialer.Timeout = timeout + + conn = new(Conn) + conn.Conn, err = tls.DialWithDialer(&dialer, network, address, tlsConfig) + if err != nil { + return nil, err + } + return conn, nil +} + +func deadlineOrTimeout(deadline time.Time, timeout time.Duration) time.Time { + if deadline.IsZero() { + return time.Now().Add(timeout) + } + return deadline +} |