69 lines
2.2 KiB
Go
69 lines
2.2 KiB
Go
package store
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import (
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"crypto/rand"
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"encoding/hex"
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"errors"
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"regexp"
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"strings"
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)
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// vanityRe is deliberately narrow: lowercase alphanumerics plus dot, dash and
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// underscore, starting with an alphanumeric, 2-64 characters. Anything that
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// could be mistaken for a path element, a dotfile or a traversal is excluded.
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var vanityRe = regexp.MustCompile(`^[a-z0-9][a-z0-9._-]{1,63}$`)
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// reserved names would shadow a route or a well-known file if they were ever
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// allowed into the object namespace.
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var reserved = map[string]bool{
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"d": true, "i": true, "api": true, "static": true, "admin": true,
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"favicon.ico": true, "robots.txt": true, "index.html": true,
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"sitemap.xml": true, "tokens.json": true, "objects": true,
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}
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var ErrBadID = errors.New("invalid name")
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// CleanID validates an id arriving from a URL or from a vanity request and
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// returns its canonical form. IDs are lowercased so that a case-insensitive
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// filesystem cannot be tricked into treating two distinct names as one object.
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//
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// This is the *only* function permitted to turn caller input into a path
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// element; every filesystem path in this package is built from its output.
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func CleanID(s string) (string, error) {
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s = strings.ToLower(strings.TrimSpace(s))
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if !vanityRe.MatchString(s) {
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return "", ErrBadID
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}
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// The regexp permits interior dots; a doubled dot or a trailing dot is
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// still refused so no spelling of a traversal survives.
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if strings.Contains(s, "..") || strings.HasSuffix(s, ".") {
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return "", ErrBadID
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}
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if reserved[s] {
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return "", ErrBadID
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}
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return s, nil
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}
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// NewUUID returns a random RFC 4122 version 4 UUID.
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func NewUUID() (string, error) {
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var b [16]byte
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if _, err := rand.Read(b[:]); err != nil {
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return "", err
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}
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b[6] = (b[6] & 0x0f) | 0x40 // version 4
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b[8] = (b[8] & 0x3f) | 0x80 // variant 10
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h := hex.EncodeToString(b[:])
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return h[:8] + "-" + h[8:12] + "-" + h[12:16] + "-" + h[16:20] + "-" + h[20:], nil
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}
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// NewSecret returns a high-entropy URL-safe secret, used for both API tokens
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// and per-object delete tokens.
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func NewSecret() (string, error) {
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var b [32]byte
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if _, err := rand.Read(b[:]); err != nil {
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return "", err
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}
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return hex.EncodeToString(b[:]), nil
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}
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