142 lines
3 KiB
Go
142 lines
3 KiB
Go
package auth
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import (
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"crypto/md5"
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"crypto/rand"
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"encoding/hex"
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"fmt"
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"io"
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"net/http"
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"strings"
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)
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const (
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algorithm = "algorithm"
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authorization = "Authorization"
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nonce = "nonce"
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opaque = "opaque"
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qop = "qop"
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realm = "realm"
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wwwAuthenticate = "Www-Authenticate"
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)
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// DigestRequest is a client for digest authentication requests.
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type digestRequest struct {
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client *http.Client
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username, password string
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nonceCount nonceCount
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}
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type nonceCount int
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func (nc nonceCount) String() string {
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return fmt.Sprintf("%08x", int(nc))
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}
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var wanted = []string{algorithm, nonce, opaque, qop, realm}
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// New makes a DigestRequest instance.
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func newDigestRequest(username, password string, client *http.Client) *digestRequest {
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return &digestRequest{
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client: client,
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username: username,
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password: password,
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}
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}
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// Do does requests as http.Do does.
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func (r *digestRequest) Do(req *http.Request) (*http.Response, error) {
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parts, err := r.makeParts(req)
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if err != nil {
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return nil, err
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}
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if parts != nil {
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req.Header.Set(authorization, r.makeAuthorization(req, parts))
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}
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return r.client.Do(req)
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}
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func (r *digestRequest) makeParts(req *http.Request) (map[string]string, error) {
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authReq, err := http.NewRequest(req.Method, req.URL.String(), nil)
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if err != nil {
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return nil, err
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}
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resp, err := r.client.Do(authReq)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusUnauthorized {
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return nil, nil
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}
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if len(resp.Header[wwwAuthenticate]) == 0 {
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return nil, fmt.Errorf("headers do not have %s", wwwAuthenticate)
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}
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headers := strings.Split(resp.Header[wwwAuthenticate][0], ",")
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parts := make(map[string]string, len(wanted))
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for _, r := range headers {
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for _, w := range wanted {
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if strings.Contains(r, w) {
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parts[w] = strings.Split(r, `"`)[1]
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}
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}
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}
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if len(parts) != len(wanted) {
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return nil, fmt.Errorf("header is invalid: %+v", parts)
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}
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return parts, nil
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}
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func getMD5(texts []string) string {
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h := md5.New()
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_, _ = io.WriteString(h, strings.Join(texts, ":"))
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return hex.EncodeToString(h.Sum(nil))
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}
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func (r *digestRequest) getNonceCount() string {
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r.nonceCount++
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return r.nonceCount.String()
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}
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func (r *digestRequest) makeAuthorization(req *http.Request, parts map[string]string) string {
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ha1 := getMD5([]string{r.username, parts[realm], r.password})
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ha2 := getMD5([]string{req.Method, req.URL.String()})
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cnonce := generateRandom(16)
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nc := r.getNonceCount()
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response := getMD5([]string{
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ha1,
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parts[nonce],
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nc,
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cnonce,
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parts[qop],
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ha2,
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})
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return fmt.Sprintf(
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`Digest username="%s", realm="%s", nonce="%s", uri="%s", algorithm=%s, qop=%s, nc=%s, cnonce="%s", response="%s", opaque="%s"`,
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r.username,
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parts[realm],
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parts[nonce],
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req.URL.String(),
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parts[algorithm],
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parts[qop],
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nc,
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cnonce,
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response,
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parts[opaque],
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)
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}
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// GenerateRandom generates random string.
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func generateRandom(n int) string {
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b := make([]byte, 8)
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_, _ = io.ReadFull(rand.Reader, b)
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return hex.EncodeToString(b)[:n]
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}
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