mirror of
https://codeberg.org/forgejo/forgejo
synced 2024-11-25 11:16:11 +01:00
72 lines
1.7 KiB
Go
72 lines
1.7 KiB
Go
package ber
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
)
|
|
|
|
func readLength(reader io.Reader) (length int, read int, err error) {
|
|
// length byte
|
|
b, err := readByte(reader)
|
|
if err != nil {
|
|
if Debug {
|
|
fmt.Printf("error reading length byte: %v\n", err)
|
|
}
|
|
return 0, 0, err
|
|
}
|
|
read++
|
|
|
|
switch {
|
|
case b == 0xFF:
|
|
// Invalid 0xFF (x.600, 8.1.3.5.c)
|
|
return 0, read, errors.New("invalid length byte 0xff")
|
|
|
|
case b == LengthLongFormBitmask:
|
|
// Indefinite form, we have to decode packets until we encounter an EOC packet (x.600, 8.1.3.6)
|
|
length = LengthIndefinite
|
|
|
|
case b&LengthLongFormBitmask == 0:
|
|
// Short definite form, extract the length from the bottom 7 bits (x.600, 8.1.3.4)
|
|
length = int(b) & LengthValueBitmask
|
|
|
|
case b&LengthLongFormBitmask != 0:
|
|
// Long definite form, extract the number of length bytes to follow from the bottom 7 bits (x.600, 8.1.3.5.b)
|
|
lengthBytes := int(b) & LengthValueBitmask
|
|
// Protect against overflow
|
|
// TODO: support big int length?
|
|
if lengthBytes > 8 {
|
|
return 0, read, errors.New("long-form length overflow")
|
|
}
|
|
for i := 0; i < lengthBytes; i++ {
|
|
b, err = readByte(reader)
|
|
if err != nil {
|
|
if Debug {
|
|
fmt.Printf("error reading long-form length byte %d: %v\n", i, err)
|
|
}
|
|
return 0, read, err
|
|
}
|
|
read++
|
|
|
|
// x.600, 8.1.3.5
|
|
length <<= 8
|
|
length |= int(b)
|
|
}
|
|
|
|
default:
|
|
return 0, read, errors.New("invalid length byte")
|
|
}
|
|
|
|
return length, read, nil
|
|
}
|
|
|
|
func encodeLength(length int) []byte {
|
|
length_bytes := encodeUnsignedInteger(uint64(length))
|
|
if length > 127 || len(length_bytes) > 1 {
|
|
longFormBytes := []byte{(LengthLongFormBitmask | byte(len(length_bytes)))}
|
|
longFormBytes = append(longFormBytes, length_bytes...)
|
|
length_bytes = longFormBytes
|
|
}
|
|
return length_bytes
|
|
}
|