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9b81d4d3ab
Preparation to make decoder use less memory and API more type safe. Now each scalar type has it's own struct type so it can store different things and enables to have a scalar interface. Also own types will enable experimenting with decode DLS designs like using chained methods that are type aware.
151 lines
3.5 KiB
Go
151 lines
3.5 KiB
Go
package rtmp
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// https://rtmp.veriskope.com/pdf/amf0-file-format-specification.pdf
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import (
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"github.com/wader/fq/format"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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"github.com/wader/fq/pkg/scalar"
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)
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.AMF0,
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Description: "Action Message Format 0",
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DecodeFn: amf0Decode,
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})
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}
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const (
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typeNumber = 0x0
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typeBoolean = 0x1
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typeString = 0x2
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typeObject = 0x3
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typeMovieClip = 0x4
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typeNull = 0x5
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typeUndefined = 0x6
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typeReference = 0x7
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typeECMAArray = 0x8
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typeObjectEnd = 0x9
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typeStrictArray = 0xa
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typeDate = 0xb
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typeLongString = 0xc
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typeUnsupported = 0xd
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typeRecordSet = 0xe
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typeXML = 0xf
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typeTypedObject = 0x10
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)
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var typeNames = scalar.UintMapSymStr{
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typeNumber: "number",
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typeBoolean: "boolean",
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typeString: "string",
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typeObject: "object",
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typeMovieClip: "movie_clip",
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typeNull: "null",
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typeUndefined: "undefined",
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typeReference: "reference",
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typeECMAArray: "ecma_array",
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typeObjectEnd: "object_end",
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typeStrictArray: "strict_array",
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typeDate: "date",
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typeLongString: "long_string",
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typeUnsupported: "unsupported",
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typeRecordSet: "record_set",
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typeXML: "xml",
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typeTypedObject: "typed_object",
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}
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func amf0DecodeValue(d *decode.D) {
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typ := d.FieldU8("type", typeNames)
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switch typ {
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case typeNumber:
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d.FieldF64("value")
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case typeBoolean:
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d.FieldU8("value")
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case typeString:
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l := d.FieldU16("length")
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d.FieldUTF8("value", int(l))
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case typeObject:
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d.FieldArray("value", func(d *decode.D) {
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var typ uint64
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for typ != typeObjectEnd {
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d.FieldStruct("pair", func(d *decode.D) {
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d.FieldStruct("key", func(d *decode.D) {
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l := d.FieldU16("length")
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d.FieldUTF8("value", int(l))
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})
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typ = d.PeekBits(8)
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d.FieldStruct("value", amf0DecodeValue)
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})
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}
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})
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case typeNull:
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d.FieldValueAny("value", nil)
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case typeUndefined:
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d.FieldValueAny("value", nil) // TODO: ?
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case typeReference:
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d.FieldU16("value") // TODO: index pointer
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case typeECMAArray:
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d.FieldU32("count")
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d.FieldArray("value", func(d *decode.D) {
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var typ uint64
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for typ != typeObjectEnd {
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d.FieldStruct("entry", func(d *decode.D) {
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d.FieldStruct("key", func(d *decode.D) {
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l := d.FieldU16("length")
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d.FieldUTF8("value", int(l))
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})
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typ = d.PeekBits(8)
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d.FieldStruct("value", amf0DecodeValue)
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})
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}
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})
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case typeObjectEnd:
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// nop
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case typeStrictArray:
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length := d.FieldU32("count")
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d.FieldArray("value", func(d *decode.D) {
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for i := uint64(0); i < length; i++ {
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d.FieldStruct("entry", amf0DecodeValue)
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}
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})
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case typeDate:
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d.FieldF64("date_time")
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d.FieldS16("local_data_time_offset")
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case typeLongString:
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l := d.FieldU32("length")
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d.FieldUTF8("value", int(l))
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case typeXML:
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l := d.FieldU16("length")
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d.FieldUTF8("value", int(l))
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case typeTypedObject:
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d.FieldStruct("class_name", func(d *decode.D) {
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l := d.FieldU16("length")
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d.FieldUTF8("value", int(l))
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})
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d.FieldArray("value", func(d *decode.D) {
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var typ uint64
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for typ != typeObjectEnd {
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d.FieldStruct("pair", func(d *decode.D) {
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d.FieldStruct("key", func(d *decode.D) {
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l := d.FieldU16("length")
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d.FieldUTF8("value", int(l))
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})
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typ = d.PeekBits(8)
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d.FieldStruct("value", amf0DecodeValue)
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})
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}
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})
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default:
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d.Fatalf("unknown type %d", typ)
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}
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}
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func amf0Decode(d *decode.D, _ any) any {
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amf0DecodeValue(d)
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return nil
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}
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