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Luhn error checking

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This commit is contained in:
Jakob Borg
2014-07-04 16:16:50 +02:00
parent c488179783
commit 3d7d4d845a
3 changed files with 70 additions and 11 deletions
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20
protocol/nodeid.go
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@@ -34,7 +34,11 @@ func NodeIDFromString(s string) (NodeID, error) {
func (n NodeID) String() string {
id := base32.StdEncoding.EncodeToString(n[:])
id = strings.Trim(id, "=")
id = luhnify(id)
id, err := luhnify(id)
if err != nil {
// Should never happen
panic(err)
}
id = chunkify(id)
return id
}
@@ -84,7 +88,7 @@ func (n *NodeID) UnmarshalText(bs []byte) error {
}
}
func luhnify(s string) string {
func luhnify(s string) (string, error) {
if len(s) != 52 {
panic("unsupported string length")
}
@@ -92,10 +96,13 @@ func luhnify(s string) string {
res := make([]string, 0, 4)
for i := 0; i < 4; i++ {
p := s[i*13 : (i+1)*13]
l := luhn.Base32.Generate(p)
l, err := luhn.Base32.Generate(p)
if err != nil {
return "", err
}
res = append(res, fmt.Sprintf("%s%c", p, l))
}
return res[0] + res[1] + res[2] + res[3]
return res[0] + res[1] + res[2] + res[3], nil
}
func unluhnify(s string) (string, error) {
@@ -106,7 +113,10 @@ func unluhnify(s string) (string, error) {
res := make([]string, 0, 4)
for i := 0; i < 4; i++ {
p := s[i*14 : (i+1)*14-1]
l := luhn.Base32.Generate(p)
l, err := luhn.Base32.Generate(p)
if err != nil {
return "", err
}
if g := fmt.Sprintf("%s%c", p, l); g != s[i*14:(i+1)*14] {
log.Printf("%q; %q", g, s[i*14:(i+1)*14])
return "", errors.New("check digit incorrect")