mirror of
https://github.com/ergochat/ergo.git
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513 lines
12 KiB
Go
513 lines
12 KiB
Go
package ber
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"math"
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"os"
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"reflect"
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)
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// MaxPacketLengthBytes specifies the maximum allowed packet size when calling ReadPacket or DecodePacket. Set to 0 for
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// no limit.
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var MaxPacketLengthBytes int64 = math.MaxInt32
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type Packet struct {
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Identifier
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Value interface{}
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ByteValue []byte
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Data *bytes.Buffer
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Children []*Packet
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Description string
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}
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type Identifier struct {
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ClassType Class
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TagType Type
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Tag Tag
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}
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type Tag uint64
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const (
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TagEOC Tag = 0x00
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TagBoolean Tag = 0x01
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TagInteger Tag = 0x02
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TagBitString Tag = 0x03
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TagOctetString Tag = 0x04
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TagNULL Tag = 0x05
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TagObjectIdentifier Tag = 0x06
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TagObjectDescriptor Tag = 0x07
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TagExternal Tag = 0x08
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TagRealFloat Tag = 0x09
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TagEnumerated Tag = 0x0a
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TagEmbeddedPDV Tag = 0x0b
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TagUTF8String Tag = 0x0c
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TagRelativeOID Tag = 0x0d
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TagSequence Tag = 0x10
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TagSet Tag = 0x11
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TagNumericString Tag = 0x12
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TagPrintableString Tag = 0x13
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TagT61String Tag = 0x14
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TagVideotexString Tag = 0x15
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TagIA5String Tag = 0x16
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TagUTCTime Tag = 0x17
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TagGeneralizedTime Tag = 0x18
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TagGraphicString Tag = 0x19
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TagVisibleString Tag = 0x1a
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TagGeneralString Tag = 0x1b
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TagUniversalString Tag = 0x1c
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TagCharacterString Tag = 0x1d
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TagBMPString Tag = 0x1e
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TagBitmask Tag = 0x1f // xxx11111b
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// HighTag indicates the start of a high-tag byte sequence
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HighTag Tag = 0x1f // xxx11111b
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// HighTagContinueBitmask indicates the high-tag byte sequence should continue
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HighTagContinueBitmask Tag = 0x80 // 10000000b
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// HighTagValueBitmask obtains the tag value from a high-tag byte sequence byte
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HighTagValueBitmask Tag = 0x7f // 01111111b
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)
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const (
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// LengthLongFormBitmask is the mask to apply to the length byte to see if a long-form byte sequence is used
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LengthLongFormBitmask = 0x80
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// LengthValueBitmask is the mask to apply to the length byte to get the number of bytes in the long-form byte sequence
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LengthValueBitmask = 0x7f
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// LengthIndefinite is returned from readLength to indicate an indefinite length
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LengthIndefinite = -1
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)
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var tagMap = map[Tag]string{
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TagEOC: "EOC (End-of-Content)",
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TagBoolean: "Boolean",
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TagInteger: "Integer",
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TagBitString: "Bit String",
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TagOctetString: "Octet String",
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TagNULL: "NULL",
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TagObjectIdentifier: "Object Identifier",
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TagObjectDescriptor: "Object Descriptor",
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TagExternal: "External",
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TagRealFloat: "Real (float)",
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TagEnumerated: "Enumerated",
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TagEmbeddedPDV: "Embedded PDV",
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TagUTF8String: "UTF8 String",
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TagRelativeOID: "Relative-OID",
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TagSequence: "Sequence and Sequence of",
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TagSet: "Set and Set OF",
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TagNumericString: "Numeric String",
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TagPrintableString: "Printable String",
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TagT61String: "T61 String",
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TagVideotexString: "Videotex String",
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TagIA5String: "IA5 String",
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TagUTCTime: "UTC Time",
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TagGeneralizedTime: "Generalized Time",
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TagGraphicString: "Graphic String",
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TagVisibleString: "Visible String",
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TagGeneralString: "General String",
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TagUniversalString: "Universal String",
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TagCharacterString: "Character String",
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TagBMPString: "BMP String",
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}
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type Class uint8
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const (
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ClassUniversal Class = 0 // 00xxxxxxb
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ClassApplication Class = 64 // 01xxxxxxb
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ClassContext Class = 128 // 10xxxxxxb
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ClassPrivate Class = 192 // 11xxxxxxb
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ClassBitmask Class = 192 // 11xxxxxxb
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)
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var ClassMap = map[Class]string{
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ClassUniversal: "Universal",
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ClassApplication: "Application",
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ClassContext: "Context",
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ClassPrivate: "Private",
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}
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type Type uint8
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const (
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TypePrimitive Type = 0 // xx0xxxxxb
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TypeConstructed Type = 32 // xx1xxxxxb
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TypeBitmask Type = 32 // xx1xxxxxb
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)
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var TypeMap = map[Type]string{
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TypePrimitive: "Primitive",
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TypeConstructed: "Constructed",
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}
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var Debug bool = false
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func PrintBytes(out io.Writer, buf []byte, indent string) {
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data_lines := make([]string, (len(buf)/30)+1)
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num_lines := make([]string, (len(buf)/30)+1)
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for i, b := range buf {
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data_lines[i/30] += fmt.Sprintf("%02x ", b)
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num_lines[i/30] += fmt.Sprintf("%02d ", (i+1)%100)
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}
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for i := 0; i < len(data_lines); i++ {
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out.Write([]byte(indent + data_lines[i] + "\n"))
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out.Write([]byte(indent + num_lines[i] + "\n\n"))
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}
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}
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func PrintPacket(p *Packet) {
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printPacket(os.Stdout, p, 0, false)
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}
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func printPacket(out io.Writer, p *Packet, indent int, printBytes bool) {
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indent_str := ""
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for len(indent_str) != indent {
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indent_str += " "
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}
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class_str := ClassMap[p.ClassType]
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tagtype_str := TypeMap[p.TagType]
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tag_str := fmt.Sprintf("0x%02X", p.Tag)
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if p.ClassType == ClassUniversal {
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tag_str = tagMap[p.Tag]
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}
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value := fmt.Sprint(p.Value)
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description := ""
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if p.Description != "" {
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description = p.Description + ": "
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}
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fmt.Fprintf(out, "%s%s(%s, %s, %s) Len=%d %q\n", indent_str, description, class_str, tagtype_str, tag_str, p.Data.Len(), value)
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if printBytes {
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PrintBytes(out, p.Bytes(), indent_str)
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}
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for _, child := range p.Children {
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printPacket(out, child, indent+1, printBytes)
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}
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}
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// ReadPacket reads a single Packet from the reader
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func ReadPacket(reader io.Reader) (*Packet, error) {
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p, _, err := readPacket(reader)
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if err != nil {
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return nil, err
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}
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return p, nil
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}
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func DecodeString(data []byte) string {
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return string(data)
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}
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func ParseInt64(bytes []byte) (ret int64, err error) {
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if len(bytes) > 8 {
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// We'll overflow an int64 in this case.
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err = fmt.Errorf("integer too large")
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return
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}
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for bytesRead := 0; bytesRead < len(bytes); bytesRead++ {
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ret <<= 8
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ret |= int64(bytes[bytesRead])
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}
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// Shift up and down in order to sign extend the result.
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ret <<= 64 - uint8(len(bytes))*8
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ret >>= 64 - uint8(len(bytes))*8
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return
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}
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func encodeInteger(i int64) []byte {
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n := int64Length(i)
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out := make([]byte, n)
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var j int
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for ; n > 0; n-- {
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out[j] = (byte(i >> uint((n-1)*8)))
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j++
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}
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return out
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}
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func int64Length(i int64) (numBytes int) {
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numBytes = 1
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for i > 127 {
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numBytes++
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i >>= 8
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}
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for i < -128 {
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numBytes++
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i >>= 8
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}
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return
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}
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// DecodePacket decodes the given bytes into a single Packet
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// If a decode error is encountered, nil is returned.
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func DecodePacket(data []byte) *Packet {
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p, _, _ := readPacket(bytes.NewBuffer(data))
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return p
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}
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// DecodePacketErr decodes the given bytes into a single Packet
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// If a decode error is encountered, nil is returned
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func DecodePacketErr(data []byte) (*Packet, error) {
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p, _, err := readPacket(bytes.NewBuffer(data))
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if err != nil {
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return nil, err
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}
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return p, nil
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}
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// readPacket reads a single Packet from the reader, returning the number of bytes read
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func readPacket(reader io.Reader) (*Packet, int, error) {
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identifier, length, read, err := readHeader(reader)
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if err != nil {
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return nil, read, err
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}
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p := &Packet{
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Identifier: identifier,
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}
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p.Data = new(bytes.Buffer)
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p.Children = make([]*Packet, 0, 2)
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p.Value = nil
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if p.TagType == TypeConstructed {
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// TODO: if universal, ensure tag type is allowed to be constructed
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// Track how much content we've read
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contentRead := 0
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for {
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if length != LengthIndefinite {
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// End if we've read what we've been told to
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if contentRead == length {
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break
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}
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// Detect if a packet boundary didn't fall on the expected length
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if contentRead > length {
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return nil, read, fmt.Errorf("expected to read %d bytes, read %d", length, contentRead)
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}
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}
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// Read the next packet
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child, r, err := readPacket(reader)
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if err != nil {
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return nil, read, err
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}
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contentRead += r
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read += r
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// Test is this is the EOC marker for our packet
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if isEOCPacket(child) {
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if length == LengthIndefinite {
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break
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}
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return nil, read, errors.New("eoc child not allowed with definite length")
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}
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// Append and continue
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p.AppendChild(child)
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}
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return p, read, nil
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}
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if length == LengthIndefinite {
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return nil, read, errors.New("indefinite length used with primitive type")
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}
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// Read definite-length content
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if MaxPacketLengthBytes > 0 && int64(length) > MaxPacketLengthBytes {
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return nil, read, fmt.Errorf("length %d greater than maximum %d", length, MaxPacketLengthBytes)
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}
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content := make([]byte, length, length)
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if length > 0 {
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_, err := io.ReadFull(reader, content)
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if err != nil {
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if err == io.EOF {
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return nil, read, io.ErrUnexpectedEOF
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}
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return nil, read, err
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}
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read += length
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}
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if p.ClassType == ClassUniversal {
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p.Data.Write(content)
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p.ByteValue = content
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switch p.Tag {
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case TagEOC:
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case TagBoolean:
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val, _ := ParseInt64(content)
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p.Value = val != 0
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case TagInteger:
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p.Value, _ = ParseInt64(content)
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case TagBitString:
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case TagOctetString:
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// the actual string encoding is not known here
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// (e.g. for LDAP content is already an UTF8-encoded
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// string). Return the data without further processing
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p.Value = DecodeString(content)
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case TagNULL:
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case TagObjectIdentifier:
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case TagObjectDescriptor:
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case TagExternal:
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case TagRealFloat:
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case TagEnumerated:
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p.Value, _ = ParseInt64(content)
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case TagEmbeddedPDV:
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case TagUTF8String:
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p.Value = DecodeString(content)
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case TagRelativeOID:
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case TagSequence:
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case TagSet:
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case TagNumericString:
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case TagPrintableString:
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p.Value = DecodeString(content)
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case TagT61String:
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case TagVideotexString:
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case TagIA5String:
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case TagUTCTime:
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case TagGeneralizedTime:
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case TagGraphicString:
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case TagVisibleString:
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case TagGeneralString:
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case TagUniversalString:
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case TagCharacterString:
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case TagBMPString:
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}
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} else {
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p.Data.Write(content)
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}
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return p, read, nil
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}
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func (p *Packet) Bytes() []byte {
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var out bytes.Buffer
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out.Write(encodeIdentifier(p.Identifier))
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out.Write(encodeLength(p.Data.Len()))
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out.Write(p.Data.Bytes())
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return out.Bytes()
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}
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func (p *Packet) AppendChild(child *Packet) {
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p.Data.Write(child.Bytes())
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p.Children = append(p.Children, child)
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}
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func Encode(ClassType Class, TagType Type, Tag Tag, Value interface{}, Description string) *Packet {
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p := new(Packet)
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p.ClassType = ClassType
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p.TagType = TagType
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p.Tag = Tag
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p.Data = new(bytes.Buffer)
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p.Children = make([]*Packet, 0, 2)
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p.Value = Value
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p.Description = Description
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if Value != nil {
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v := reflect.ValueOf(Value)
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if ClassType == ClassUniversal {
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switch Tag {
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case TagOctetString:
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sv, ok := v.Interface().(string)
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if ok {
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p.Data.Write([]byte(sv))
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}
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}
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}
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}
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return p
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}
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func NewSequence(Description string) *Packet {
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return Encode(ClassUniversal, TypeConstructed, TagSequence, nil, Description)
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}
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func NewBoolean(ClassType Class, TagType Type, Tag Tag, Value bool, Description string) *Packet {
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intValue := int64(0)
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if Value {
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intValue = 1
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}
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p := Encode(ClassType, TagType, Tag, nil, Description)
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p.Value = Value
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p.Data.Write(encodeInteger(intValue))
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return p
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}
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func NewInteger(ClassType Class, TagType Type, Tag Tag, Value interface{}, Description string) *Packet {
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p := Encode(ClassType, TagType, Tag, nil, Description)
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p.Value = Value
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switch v := Value.(type) {
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case int:
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p.Data.Write(encodeInteger(int64(v)))
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case uint:
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p.Data.Write(encodeInteger(int64(v)))
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case int64:
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p.Data.Write(encodeInteger(v))
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case uint64:
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// TODO : check range or add encodeUInt...
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p.Data.Write(encodeInteger(int64(v)))
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case int32:
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p.Data.Write(encodeInteger(int64(v)))
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case uint32:
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p.Data.Write(encodeInteger(int64(v)))
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case int16:
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p.Data.Write(encodeInteger(int64(v)))
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case uint16:
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p.Data.Write(encodeInteger(int64(v)))
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case int8:
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p.Data.Write(encodeInteger(int64(v)))
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case uint8:
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p.Data.Write(encodeInteger(int64(v)))
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default:
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// TODO : add support for big.Int ?
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panic(fmt.Sprintf("Invalid type %T, expected {u|}int{64|32|16|8}", v))
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}
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return p
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}
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func NewString(ClassType Class, TagType Type, Tag Tag, Value, Description string) *Packet {
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p := Encode(ClassType, TagType, Tag, nil, Description)
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p.Value = Value
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p.Data.Write([]byte(Value))
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return p
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}
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