oppi.li
1package syntax
2
3import (
4 "errors"
5 "regexp"
6 "strings"
7)
8
9// Represents a CIDv1 in string format, as would pass Lexicon syntax validation.
10//
11// You usually want to use the github.com/ipfs/go-cid package and type when working with CIDs ("Links") in atproto. This specific type (syntax.CID) is an informal/incomplete helper specifically for doing fast string verification or pass-through without parsing, re-serialization, or normalization.
12//
13// Always use [ParseCID] instead of wrapping strings directly, especially when working with network input.
14type CID string
15
16var cidRegex = regexp.MustCompile(`^[a-zA-Z0-9+=]{8,256}$`)
17
18func ParseCID(raw string) (CID, error) {
19 if raw == "" {
20 return "", errors.New("expected CID, got empty string")
21 }
22 if len(raw) > 256 {
23 return "", errors.New("CID is too long (256 chars max)")
24 }
25 if len(raw) < 8 {
26 return "", errors.New("CID is too short (8 chars min)")
27 }
28
29 if !cidRegex.MatchString(raw) {
30 return "", errors.New("CID syntax didn't validate via regex")
31 }
32 if strings.HasPrefix(raw, "Qmb") {
33 return "", errors.New("CIDv0 not allowed in this version of atproto")
34 }
35 return CID(raw), nil
36}
37
38func (c CID) String() string {
39 return string(c)
40}
41
42func (c CID) MarshalText() ([]byte, error) {
43 return []byte(c.String()), nil
44}
45
46func (c *CID) UnmarshalText(text []byte) error {
47 cid, err := ParseCID(string(text))
48 if err != nil {
49 return err
50 }
51 *c = cid
52 return nil
53}