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github.com/miekg/dns 在 go 1.7.3 中的使用
clq
浏览(0) - 2018-12-23 22:17:39 发表 编辑

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[2018-12-23 23:00:23 最后更新]
github.com/miekg/dns  在 go 1.7.3 中的使用

目前的最新版本应该是用到了很多 go 1.10 后的东西,所以在 go 1.7.3 下要改动好几个地方.

1.参考我们的另一文章增加 strings builder 的文件;

2.参考 https://golang.org/src/time/time.go 中的

//--------------------------------------------------
// Until returns the duration until t.
// It is shorthand for t.Sub(time.Now()).
func Until(t Time) Duration {
    return t.Sub(Now())
}

//--------------------------------------------------

修改 github.com\miekg\dns\client.go 中的以下函数
//--------------------------------------------------
// ExchangeContext acts like Exchange, but honors the deadline on the provided
// context, if present. If there is both a context deadline and a configured
// timeout on the client, the earliest of the two takes effect.
func (c *Client) ExchangeContext(ctx context.Context, m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
    var timeout time.Duration
    if deadline, ok := ctx.Deadline(); !ok {
        timeout = 0
    } else {
//clq test        timeout = time.Until(deadline)
        timeout = deadline.Sub(time.Now());
    }
    // not passing the context to the underlying calls, as the API does not support
    // context. For timeouts you should set up Client.Dialer and call Client.Exchange.
    // TODO(tmthrgd,miekg): this is a race condition.
    c.Dialer = &net.Dialer{Timeout: timeout}
    return c.Exchange(m, a)
}
//--------------------------------------------------

3.替换 x:\Go\src\encoding\base32\base32.go 文件
修改 github.com\miekg\dns\msg_helpers.go 中以下代码
//--------------------------------------------------
//clq test//var base32HexNoPadEncoding = base32.HexEncoding.WithPadding(base32.NoPadding)
//var base32HexNoPadEncoding = base32.HexEncoding.WithPadding(-1) //clq test
//var base32HexNoPadEncoding = base32.NewEncoding(base32.encodeHex) //clq test
var base32HexNoPadEncoding = base32.NewEncoding("0123456789ABCDEFGHIJKLMNOPQRSTUV") //clq test
//--------------------------------------------------

注意以上代码的参数,根据 https://www.codercto.com/a/44917.html  的文章,这个参数就是专用于 dns 的.



clq
2018-12-23 22:18:14 发表 编辑

现在很忙,以后我们再找时间完事传到 github 上去.

clq
2018-12-23 23:00:23 发表 编辑

encoding\base32\base32.go

目前最新的源码如下,直接来自 https://golang.org/src/encoding/base32/base32.go
--------------------------------------------------
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package base32 implements base32 encoding as specified by RFC 4648.
package base32

import (
    "bytes"
    "io"
    "strconv"
    "strings"
)

/*
 * Encodings
 */

// An Encoding is a radix 32 encoding/decoding scheme, defined by a
// 32-character alphabet. The most common is the "base32" encoding
// introduced for SASL GSSAPI and standardized in RFC 4648.
// The alternate "base32hex" encoding is used in DNSSEC.
type Encoding struct {
    encode    [32]byte
    decodeMap [256]byte
    padChar   rune
}

const (
    StdPadding rune = '=' // Standard padding character
    NoPadding  rune = -1  // No padding
)

const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
const encodeHex = "0123456789ABCDEFGHIJKLMNOPQRSTUV"

// NewEncoding returns a new Encoding defined by the given alphabet,
// which must be a 32-byte string.
func NewEncoding(encoder string) *Encoding {
    if len(encoder) != 32 {
        panic("encoding alphabet is not 32-bytes long")
    }

    e := new(Encoding)
    copy(e.encode[:], encoder)
    e.padChar = StdPadding

    for i := 0; i < len(e.decodeMap); i++ {
        e.decodeMap[i] = 0xFF
    }
    for i := 0; i < len(encoder); i++ {
        e.decodeMap[encoder[i]] = byte(i)
    }
    return e
}

// StdEncoding is the standard base32 encoding, as defined in
// RFC 4648.
var StdEncoding = NewEncoding(encodeStd)

// HexEncoding is the ``Extended Hex Alphabet'' defined in RFC 4648.
// It is typically used in DNS.
var HexEncoding = NewEncoding(encodeHex)

var removeNewlinesMapper = func(r rune) rune {
    if r == '\r' || r == '\n' {
        return -1
    }
    return r
}

// WithPadding creates a new encoding identical to enc except
// with a specified padding character, or NoPadding to disable padding.
// The padding character must not be '\r' or '\n', must not
// be contained in the encoding's alphabet and must be a rune equal or
// below '\xff'.
func (enc Encoding) WithPadding(padding rune) *Encoding {
    if padding == '\r' || padding == '\n' || padding > 0xff {
        panic("invalid padding")
    }

    for i := 0; i < len(enc.encode); i++ {
        if rune(enc.encode[i]) == padding {
            panic("padding contained in alphabet")
        }
    }

    enc.padChar = padding
    return &enc
}

/*
 * Encoder
 */

// Encode encodes src using the encoding enc, writing
// EncodedLen(len(src)) bytes to dst.
//
// The encoding pads the output to a multiple of 8 bytes,
// so Encode is not appropriate for use on individual blocks
// of a large data stream. Use NewEncoder() instead.
func (enc *Encoding) Encode(dst, src []byte) {
    for len(src) > 0 {
        var b [8]byte

        // Unpack 8x 5-bit source blocks into a 5 byte
        // destination quantum
        switch len(src) {
        default:
            b[7] = src[4] & 0x1F
            b[6] = src[4] >> 5
            fallthrough
        case 4:
            b[6] |= (src[3] << 3) & 0x1F
            b[5] = (src[3] >> 2) & 0x1F
            b[4] = src[3] >> 7
            fallthrough
        case 3:
            b[4] |= (src[2] << 1) & 0x1F
            b[3] = (src[2] >> 4) & 0x1F
            fallthrough
        case 2:
            b[3] |= (src[1] << 4) & 0x1F
            b[2] = (src[1] >> 1) & 0x1F
            b[1] = (src[1] >> 6) & 0x1F
            fallthrough
        case 1:
            b[1] |= (src[0] << 2) & 0x1F
            b[0] = src[0] >> 3
        }

        // Encode 5-bit blocks using the base32 alphabet
        size := len(dst)
        if size >= 8 {
            // Common case, unrolled for extra performance
            dst[0] = enc.encode[b[0]&31]
            dst[1] = enc.encode[b[1]&31]
            dst[2] = enc.encode[b[2]&31]
            dst[3] = enc.encode[b[3]&31]
            dst[4] = enc.encode[b[4]&31]
            dst[5] = enc.encode[b[5]&31]
            dst[6] = enc.encode[b[6]&31]
            dst[7] = enc.encode[b[7]&31]
        } else {
            for i := 0; i < size; i++ {
                dst[i] = enc.encode[b[i]&31]
            }
        }

        // Pad the final quantum
        if len(src) < 5 {
            if enc.padChar == NoPadding {
                break
            }

            dst[7] = byte(enc.padChar)
            if len(src) < 4 {
                dst[6] = byte(enc.padChar)
                dst[5] = byte(enc.padChar)
                if len(src) < 3 {
                    dst[4] = byte(enc.padChar)
                    if len(src) < 2 {
                        dst[3] = byte(enc.padChar)
                        dst[2] = byte(enc.padChar)
                    }
                }
            }

            break
        }

        src = src[5:]
        dst = dst[8:]
    }
}

// EncodeToString returns the base32 encoding of src.
func (enc *Encoding) EncodeToString(src []byte) string {
    buf := make([]byte, enc.EncodedLen(len(src)))
    enc.Encode(buf, src)
    return string(buf)
}

type encoder struct {
    err  error
    enc  *Encoding
    w    io.Writer
    buf  [5]byte    // buffered data waiting to be encoded
    nbuf int        // number of bytes in buf
    out  [1024]byte // output buffer
}

func (e *encoder) Write(p []byte) (n int, err error) {
    if e.err != nil {
        return 0, e.err
    }

    // Leading fringe.
    if e.nbuf > 0 {
        var i int
        for i = 0; i < len(p) && e.nbuf < 5; i++ {
            e.buf[e.nbuf] = p[i]
            e.nbuf++
        }
        n += i
        p = p[i:]
        if e.nbuf < 5 {
            return
        }
        e.enc.Encode(e.out[0:], e.buf[0:])
        if _, e.err = e.w.Write(e.out[0:8]); e.err != nil {
            return n, e.err
        }
        e.nbuf = 0
    }

    // Large interior chunks.
    for len(p) >= 5 {
        nn := len(e.out) / 8 * 5
        if nn > len(p) {
            nn = len(p)
            nn -= nn % 5
        }
        e.enc.Encode(e.out[0:], p[0:nn])
        if _, e.err = e.w.Write(e.out[0 : nn/5*8]); e.err != nil {
            return n, e.err
        }
        n += nn
        p = p[nn:]
    }

    // Trailing fringe.
    for i := 0; i < len(p); i++ {
        e.buf[i] = p[i]
    }
    e.nbuf = len(p)
    n += len(p)
    return
}

// Close flushes any pending output from the encoder.
// It is an error to call Write after calling Close.
func (e *encoder) Close() error {
    // If there's anything left in the buffer, flush it out
    if e.err == nil && e.nbuf > 0 {
        e.enc.Encode(e.out[0:], e.buf[0:e.nbuf])
        encodedLen := e.enc.EncodedLen(e.nbuf)
        e.nbuf = 0
        _, e.err = e.w.Write(e.out[0:encodedLen])
    }
    return e.err
}

// NewEncoder returns a new base32 stream encoder. Data written to
// the returned writer will be encoded using enc and then written to w.
// Base32 encodings operate in 5-byte blocks; when finished
// writing, the caller must Close the returned encoder to flush any
// partially written blocks.
func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser {
    return &encoder{enc: enc, w: w}
}

// EncodedLen returns the length in bytes of the base32 encoding
// of an input buffer of length n.
func (enc *Encoding) EncodedLen(n int) int {
    if enc.padChar == NoPadding {
        return (n*8 + 4) / 5
    }
    return (n + 4) / 5 * 8
}

/*
 * Decoder
 */

type CorruptInputError int64

func (e CorruptInputError) Error() string {
    return "illegal base32 data at input byte " + strconv.FormatInt(int64(e), 10)
}

// decode is like Decode but returns an additional 'end' value, which
// indicates if end-of-message padding was encountered and thus any
// additional data is an error. This method assumes that src has been
// stripped of all supported whitespace ('\r' and '\n').
func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
    olen := len(src)
    for len(src) > 0 && !end {
        // Decode quantum using the base32 alphabet
        var dbuf [8]byte
        dlen := 8

        for j := 0; j < 8; {

            // We have reached the end and are missing padding
            if len(src) == 0 && enc.padChar != NoPadding {
                return n, false, CorruptInputError(olen - len(src) - j)
            }

            // We have reached the end and are not expecing any padding
            if len(src) == 0 && enc.padChar == NoPadding {
                dlen, end = j, true
                break
            }

            in := src[0]
            src = src[1:]
            if in == byte(enc.padChar) && j >= 2 && len(src) < 8 {
                // We've reached the end and there's padding
                if len(src)+j < 8-1 {
                    // not enough padding
                    return n, false, CorruptInputError(olen)
                }
                for k := 0; k < 8-1-j; k++ {
                    if len(src) > k && src[k] != byte(enc.padChar) {
                        // incorrect padding
                        return n, false, CorruptInputError(olen - len(src) + k - 1)
                    }
                }
                dlen, end = j, true
                // 7, 5 and 2 are not valid padding lengths, and so 1, 3 and 6 are not
                // valid dlen values. See RFC 4648 Section 6 "Base 32 Encoding" listing
                // the five valid padding lengths, and Section 9 "Illustrations and
                // Examples" for an illustration for how the 1st, 3rd and 6th base32
                // src bytes do not yield enough information to decode a dst byte.
                if dlen == 1 || dlen == 3 || dlen == 6 {
                    return n, false, CorruptInputError(olen - len(src) - 1)
                }
                break
            }
            dbuf[j] = enc.decodeMap[in]
            if dbuf[j] == 0xFF {
                return n, false, CorruptInputError(olen - len(src) - 1)
            }
            j++
        }

        // Pack 8x 5-bit source blocks into 5 byte destination
        // quantum
        switch dlen {
        case 8:
            dst[4] = dbuf[6]<<5 | dbuf[7]
            fallthrough
        case 7:
            dst[3] = dbuf[4]<<7 | dbuf[5]<<2 | dbuf[6]>>3
            fallthrough
        case 5:
            dst[2] = dbuf[3]<<4 | dbuf[4]>>1
            fallthrough
        case 4:
            dst[1] = dbuf[1]<<6 | dbuf[2]<<1 | dbuf[3]>>4
            fallthrough
        case 2:
            dst[0] = dbuf[0]<<3 | dbuf[1]>>2
        }

        if !end {
            dst = dst[5:]
        }

        switch dlen {
        case 2:
            n += 1
        case 4:
            n += 2
        case 5:
            n += 3
        case 7:
            n += 4
        case 8:
            n += 5
        }
    }
    return n, end, nil
}

// Decode decodes src using the encoding enc. It writes at most
// DecodedLen(len(src)) bytes to dst and returns the number of bytes
// written. If src contains invalid base32 data, it will return the
// number of bytes successfully written and CorruptInputError.
// New line characters (\r and \n) are ignored.
func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
    src = bytes.Map(removeNewlinesMapper, src)
    n, _, err = enc.decode(dst, src)
    return
}

// DecodeString returns the bytes represented by the base32 string s.
func (enc *Encoding) DecodeString(s string) ([]byte, error) {
    s = strings.Map(removeNewlinesMapper, s)
    dbuf := make([]byte, enc.DecodedLen(len(s)))
    n, _, err := enc.decode(dbuf, []byte(s))
    return dbuf[:n], err
}

type decoder struct {
    err    error
    enc    *Encoding
    r      io.Reader
    end    bool       // saw end of message
    buf    [1024]byte // leftover input
    nbuf   int
    out    []byte // leftover decoded output
    outbuf [1024 / 8 * 5]byte
}

func readEncodedData(r io.Reader, buf []byte, min int, expectsPadding bool) (n int, err error) {
    for n < min && err == nil {
        var nn int
        nn, err = r.Read(buf[n:])
        n += nn
    }
    // data was read, less than min bytes could be read
    if n < min && n > 0 && err == io.EOF {
        err = io.ErrUnexpectedEOF
    }
    // no data was read, the buffer already contains some data
    // when padding is disabled this is not an error, as the message can be of
    // any length
    if expectsPadding && min < 8 && n == 0 && err == io.EOF {
        err = io.ErrUnexpectedEOF
    }
    return
}

func (d *decoder) Read(p []byte) (n int, err error) {
    // Use leftover decoded output from last read.
    if len(d.out) > 0 {
        n = copy(p, d.out)
        d.out = d.out[n:]
        if len(d.out) == 0 {
            return n, d.err
        }
        return n, nil
    }

    if d.err != nil {
        return 0, d.err
    }

    // Read a chunk.
    nn := len(p) / 5 * 8
    if nn < 8 {
        nn = 8
    }
    if nn > len(d.buf) {
        nn = len(d.buf)
    }

    // Minimum amount of bytes that needs to be read each cycle
    var min int
    var expectsPadding bool
    if d.enc.padChar == NoPadding {
        min = 1
        expectsPadding = false
    } else {
        min = 8 - d.nbuf
        expectsPadding = true
    }

    nn, d.err = readEncodedData(d.r, d.buf[d.nbuf:nn], min, expectsPadding)
    d.nbuf += nn
    if d.nbuf < min {
        return 0, d.err
    }

    // Decode chunk into p, or d.out and then p if p is too small.
    var nr int
    if d.enc.padChar == NoPadding {
        nr = d.nbuf
    } else {
        nr = d.nbuf / 8 * 8
    }
    nw := d.enc.DecodedLen(d.nbuf)

    if nw > len(p) {
        nw, d.end, err = d.enc.decode(d.outbuf[0:], d.buf[0:nr])
        d.out = d.outbuf[0:nw]
        n = copy(p, d.out)
        d.out = d.out[n:]
    } else {
        n, d.end, err = d.enc.decode(p, d.buf[0:nr])
    }
    d.nbuf -= nr
    for i := 0; i < d.nbuf; i++ {
        d.buf[i] = d.buf[i+nr]
    }

    if err != nil && (d.err == nil || d.err == io.EOF) {
        d.err = err
    }

    if len(d.out) > 0 {
        // We cannot return all the decoded bytes to the caller in this
        // invocation of Read, so we return a nil error to ensure that Read
        // will be called again.  The error stored in d.err, if any, will be
        // returned with the last set of decoded bytes.
        return n, nil
    }

    return n, d.err
}

type newlineFilteringReader struct {
    wrapped io.Reader
}

func (r *newlineFilteringReader) Read(p []byte) (int, error) {
    n, err := r.wrapped.Read(p)
    for n > 0 {
        offset := 0
        for i, b := range p[0:n] {
            if b != '\r' && b != '\n' {
                if i != offset {
                    p[offset] = b
                }
                offset++
            }
        }
        if err != nil || offset > 0 {
            return offset, err
        }
        // Previous buffer entirely whitespace, read again
        n, err = r.wrapped.Read(p)
    }
    return n, err
}

// NewDecoder constructs a new base32 stream decoder.
func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
    return &decoder{enc: enc, r: &newlineFilteringReader{r}}
}

// DecodedLen returns the maximum length in bytes of the decoded data
// corresponding to n bytes of base32-encoded data.
func (enc *Encoding) DecodedLen(n int) int {
    if enc.padChar == NoPadding {
        return n * 5 / 8
    }

    return n / 8 * 5
}


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该采集也在以下书单中



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