42 lines
1.2 KiB
Go
42 lines
1.2 KiB
Go
// Package hexutil decodes hex strings in the loose formats people paste.
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package hexutil
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import (
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"encoding/hex"
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"fmt"
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"strings"
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)
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// Decode decodes a hex string, tolerating common formatting:
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// whitespace and newlines, ':' '-' ',' '.' separators, and "0x" / "\x" byte prefixes.
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// So "45 00 00 3c", "45:00:00:3c", "0x45,0x00", "\x45\x00" and "4500003c" all work.
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func Decode(s string) ([]byte, error) {
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s = strings.NewReplacer(`\x`, " ", `\X`, " ", "0x", " ", "0X", " ").Replace(s)
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digits := make([]byte, 0, len(s))
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for i := 0; i < len(s); i++ {
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c := s[i]
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switch {
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case isHexDigit(c):
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digits = append(digits, c)
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case c == ' ' || c == '\t' || c == '\n' || c == '\r' ||
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c == ':' || c == '-' || c == ',' || c == '.':
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// separator
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default:
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return nil, fmt.Errorf("invalid character %q in hex input", c)
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}
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}
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if len(digits)%2 != 0 {
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return nil, fmt.Errorf("odd number of hex digits (%d)", len(digits))
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}
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out := make([]byte, len(digits)/2)
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if _, err := hex.Decode(out, digits); err != nil {
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return nil, err
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}
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return out, nil
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}
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func isHexDigit(c byte) bool {
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return '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F'
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}
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