mirror of
https://github.com/netbirdio/netbird.git
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306 lines
8.3 KiB
Go
306 lines
8.3 KiB
Go
package jwtclaims
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import (
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"bytes"
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"crypto/rsa"
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"crypto/x509"
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"encoding/base64"
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"encoding/binary"
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"encoding/json"
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"encoding/pem"
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"errors"
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"fmt"
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"math/big"
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"net/http"
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"strconv"
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"strings"
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"sync"
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"time"
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"github.com/golang-jwt/jwt"
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log "github.com/sirupsen/logrus"
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)
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// Options is a struct for specifying configuration options for the middleware.
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type Options struct {
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// The function that will return the Key to validate the JWT.
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// It can be either a shared secret or a public key.
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// Default value: nil
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ValidationKeyGetter jwt.Keyfunc
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// The name of the property in the request where the user information
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// from the JWT will be stored.
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// Default value: "user"
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UserProperty string
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// The function that will be called when there's an error validating the token
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// Default value:
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CredentialsOptional bool
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// A function that extracts the token from the request
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// Default: FromAuthHeader (i.e., from Authorization header as bearer token)
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Debug bool
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// When set, all requests with the OPTIONS method will use authentication
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// Default: false
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EnableAuthOnOptions bool
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// When set, the middelware verifies that tokens are signed with the specific signing algorithm
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// If the signing method is not constant the ValidationKeyGetter callback can be used to implement additional checks
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// Important to avoid security issues described here: https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries/
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// Default: nil
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SigningMethod jwt.SigningMethod
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}
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// Jwks is a collection of JSONWebKey obtained from Config.HttpServerConfig.AuthKeysLocation
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type Jwks struct {
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Keys []JSONWebKey `json:"keys"`
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expiresInTime time.Time
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}
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// JSONWebKey is a representation of a Jason Web Key
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type JSONWebKey struct {
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Kty string `json:"kty"`
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Kid string `json:"kid"`
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Use string `json:"use"`
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N string `json:"n"`
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E string `json:"e"`
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X5c []string `json:"x5c"`
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}
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// JWTValidator struct to handle token validation and parsing
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type JWTValidator struct {
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options Options
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}
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// NewJWTValidator constructor
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func NewJWTValidator(issuer string, audienceList []string, keysLocation string, idpSignkeyRefreshEnabled bool) (*JWTValidator, error) {
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keys, err := getPemKeys(keysLocation)
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if err != nil {
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return nil, err
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}
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var lock sync.Mutex
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options := Options{
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ValidationKeyGetter: func(token *jwt.Token) (interface{}, error) {
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// Verify 'aud' claim
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var checkAud bool
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for _, audience := range audienceList {
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checkAud = token.Claims.(jwt.MapClaims).VerifyAudience(audience, false)
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if checkAud {
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break
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}
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}
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if !checkAud {
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return token, errors.New("invalid audience")
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}
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// Verify 'issuer' claim
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checkIss := token.Claims.(jwt.MapClaims).VerifyIssuer(issuer, false)
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if !checkIss {
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return token, errors.New("invalid issuer")
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}
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// If keys are rotated, verify the keys prior to token validation
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if idpSignkeyRefreshEnabled {
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// If the keys are invalid, retrieve new ones
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if !keys.stillValid() {
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lock.Lock()
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defer lock.Unlock()
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refreshedKeys, err := getPemKeys(keysLocation)
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if err != nil {
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log.Debugf("cannot get JSONWebKey: %v, falling back to old keys", err)
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refreshedKeys = keys
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}
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keys = refreshedKeys
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}
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}
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cert, err := getPemCert(token, keys)
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if err != nil {
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return nil, err
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}
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result, _ := jwt.ParseRSAPublicKeyFromPEM([]byte(cert))
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return result, nil
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},
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SigningMethod: jwt.SigningMethodRS256,
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EnableAuthOnOptions: false,
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}
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if options.UserProperty == "" {
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options.UserProperty = "user"
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}
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return &JWTValidator{
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options: options,
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}, nil
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}
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// ValidateAndParse validates the token and returns the parsed token
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func (m *JWTValidator) ValidateAndParse(token string) (*jwt.Token, error) {
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// If the token is empty...
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if token == "" {
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// Check if it was required
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if m.options.CredentialsOptional {
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log.Debugf("no credentials found (CredentialsOptional=true)")
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// No error, just no token (and that is ok given that CredentialsOptional is true)
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return nil, nil
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}
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// If we get here, the required token is missing
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errorMsg := "required authorization token not found"
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log.Debugf(" Error: No credentials found (CredentialsOptional=false)")
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return nil, fmt.Errorf(errorMsg)
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}
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// Now parse the token
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parsedToken, err := jwt.Parse(token, m.options.ValidationKeyGetter)
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// Check if there was an error in parsing...
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if err != nil {
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log.Debugf("error parsing token: %v", err)
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return nil, fmt.Errorf("Error parsing token: %w", err)
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}
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if m.options.SigningMethod != nil && m.options.SigningMethod.Alg() != parsedToken.Header["alg"] {
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errorMsg := fmt.Sprintf("Expected %s signing method but token specified %s",
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m.options.SigningMethod.Alg(),
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parsedToken.Header["alg"])
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log.Debugf("error validating token algorithm: %s", errorMsg)
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return nil, fmt.Errorf("error validating token algorithm: %s", errorMsg)
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}
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// Check if the parsed token is valid...
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if !parsedToken.Valid {
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errorMsg := "token is invalid"
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log.Debugf(errorMsg)
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return nil, errors.New(errorMsg)
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}
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return parsedToken, nil
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}
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// stillValid returns true if the JSONWebKey still valid and have enough time to be used
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func (jwks *Jwks) stillValid() bool {
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return jwks.expiresInTime.IsZero() && time.Now().Add(5*time.Second).Before(jwks.expiresInTime)
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}
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func getPemKeys(keysLocation string) (*Jwks, error) {
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resp, err := http.Get(keysLocation)
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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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jwks := &Jwks{}
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err = json.NewDecoder(resp.Body).Decode(jwks)
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if err != nil {
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return jwks, err
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}
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cacheControlHeader := resp.Header.Get("Cache-Control")
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expiresIn := getMaxAgeFromCacheHeader(cacheControlHeader)
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jwks.expiresInTime = time.Now().Add(time.Duration(expiresIn) * time.Second)
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return jwks, err
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}
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func getPemCert(token *jwt.Token, jwks *Jwks) (string, error) {
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// todo as we load the jkws when the server is starting, we should build a JKS map with the pem cert at the boot time
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cert := ""
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for k := range jwks.Keys {
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if token.Header["kid"] != jwks.Keys[k].Kid {
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continue
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}
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if len(jwks.Keys[k].X5c) != 0 {
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cert = "-----BEGIN CERTIFICATE-----\n" + jwks.Keys[k].X5c[0] + "\n-----END CERTIFICATE-----"
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return cert, nil
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}
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log.Debugf("generating validation pem from JWK")
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return generatePemFromJWK(jwks.Keys[k])
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}
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return "", errors.New("unable to find appropriate key")
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}
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func generatePemFromJWK(jwk JSONWebKey) (string, error) {
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decodedModulus, err := base64.RawURLEncoding.DecodeString(jwk.N)
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if err != nil {
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return "", fmt.Errorf("unable to decode JWK modulus, error: %s", err)
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}
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intModules := big.NewInt(0)
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intModules.SetBytes(decodedModulus)
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exponent, err := convertExponentStringToInt(jwk.E)
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if err != nil {
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return "", fmt.Errorf("unable to decode JWK exponent, error: %s", err)
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}
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publicKey := &rsa.PublicKey{
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N: intModules,
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E: exponent,
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}
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derKey, err := x509.MarshalPKIXPublicKey(publicKey)
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if err != nil {
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return "", fmt.Errorf("unable to convert public key to DER, error: %s", err)
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}
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block := &pem.Block{
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Type: "RSA PUBLIC KEY",
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Bytes: derKey,
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}
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var out bytes.Buffer
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err = pem.Encode(&out, block)
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if err != nil {
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return "", fmt.Errorf("unable to encode Pem block , error: %s", err)
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}
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return out.String(), nil
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}
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func convertExponentStringToInt(stringExponent string) (int, error) {
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decodedString, err := base64.StdEncoding.DecodeString(stringExponent)
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if err != nil {
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return 0, err
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}
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exponentBytes := decodedString
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if len(decodedString) < 8 {
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exponentBytes = make([]byte, 8-len(decodedString), 8)
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exponentBytes = append(exponentBytes, decodedString...)
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}
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bytesReader := bytes.NewReader(exponentBytes)
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var exponent uint64
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err = binary.Read(bytesReader, binary.BigEndian, &exponent)
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if err != nil {
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return 0, err
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}
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return int(exponent), nil
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}
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// getMaxAgeFromCacheHeader extracts max-age directive from the Cache-Control header
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func getMaxAgeFromCacheHeader(cacheControl string) int {
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// Split into individual directives
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directives := strings.Split(cacheControl, ",")
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for _, directive := range directives {
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directive = strings.TrimSpace(directive)
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if strings.HasPrefix(directive, "max-age=") {
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// Extract the max-age value
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maxAgeStr := strings.TrimPrefix(directive, "max-age=")
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maxAge, err := strconv.Atoi(maxAgeStr)
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if err != nil {
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log.Debugf("error parsing max-age: %v", err)
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return 0
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}
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return maxAge
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}
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}
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return 0
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}
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