mirror of
https://github.com/wader/fq.git
synced 2024-12-23 21:31:33 +03:00
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.
98 lines
2.1 KiB
Go
98 lines
2.1 KiB
Go
package bencode
|
|
|
|
// https://wiki.theory.org/BitTorrentSpecification#Bencoding
|
|
|
|
import (
|
|
"embed"
|
|
"strconv"
|
|
|
|
"github.com/wader/fq/format"
|
|
"github.com/wader/fq/pkg/decode"
|
|
"github.com/wader/fq/pkg/interp"
|
|
"github.com/wader/fq/pkg/scalar"
|
|
)
|
|
|
|
//go:embed bencode.jq
|
|
//go:embed bencode.md
|
|
var bencodeFS embed.FS
|
|
|
|
func init() {
|
|
interp.RegisterFormat(decode.Format{
|
|
Name: format.BENCODE,
|
|
Description: "BitTorrent bencoding",
|
|
DecodeFn: decodeBencode,
|
|
Functions: []string{"torepr"},
|
|
})
|
|
interp.RegisterFS(bencodeFS)
|
|
}
|
|
|
|
var typeToNames = scalar.StrMapSymStr{
|
|
"d": "dictionary",
|
|
"i": "integer",
|
|
"l": "list",
|
|
"0": "string",
|
|
"1": "string",
|
|
"2": "string",
|
|
"3": "string",
|
|
"4": "string",
|
|
"5": "string",
|
|
"6": "string",
|
|
"7": "string",
|
|
"8": "string",
|
|
"9": "string",
|
|
}
|
|
|
|
func decodeStrIntUntil(b byte) func(d *decode.D) int64 {
|
|
return func(d *decode.D) int64 {
|
|
// 21 is sign + longest 64 bit in base 10
|
|
i := d.PeekFindByte(b, 21)
|
|
if i == -1 {
|
|
d.Fatalf("decodeStrIntUntil: failed to find %v", b)
|
|
}
|
|
s := d.UTF8(int(i))
|
|
n, err := strconv.ParseInt(s, 10, 64)
|
|
if err != nil {
|
|
d.Fatalf("decodeStrIntUntil: %q: %s", s, err)
|
|
}
|
|
return n
|
|
}
|
|
}
|
|
|
|
func decodeBencodeValue(d *decode.D) {
|
|
typ := d.FieldUTF8("type", 1, typeToNames)
|
|
switch typ {
|
|
case "0", "1", "2", "3", "4", "5", "6", "7", "8", "9":
|
|
d.SeekRel(-8)
|
|
length := d.FieldSintFn("length", decodeStrIntUntil(':'))
|
|
d.FieldUTF8("separator", 1, d.StrAssert(":"))
|
|
d.FieldUTF8("value", int(length))
|
|
case "i":
|
|
d.FieldSintFn("value", decodeStrIntUntil('e'))
|
|
d.FieldUTF8("end", 1, d.StrAssert("e"))
|
|
case "l":
|
|
d.FieldArray("values", func(d *decode.D) {
|
|
for d.PeekBits(8) != 'e' {
|
|
d.FieldStruct("value", decodeBencodeValue)
|
|
}
|
|
})
|
|
d.FieldUTF8("end", 1, d.StrAssert("e"))
|
|
case "d":
|
|
d.FieldArray("pairs", func(d *decode.D) {
|
|
for d.PeekBits(8) != 'e' {
|
|
d.FieldStruct("pair", func(d *decode.D) {
|
|
d.FieldStruct("key", decodeBencodeValue)
|
|
d.FieldStruct("value", decodeBencodeValue)
|
|
})
|
|
}
|
|
})
|
|
d.FieldUTF8("end", 1, d.StrAssert("e"))
|
|
default:
|
|
d.Fatalf("unknown type %v", typ)
|
|
}
|
|
}
|
|
|
|
func decodeBencode(d *decode.D, _ any) any {
|
|
decodeBencodeValue(d)
|
|
return nil
|
|
}
|