148 lines
3.7 KiB
Go
148 lines
3.7 KiB
Go
package jwt
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import (
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"bytes"
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"encoding/base64"
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"encoding/json"
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"fmt"
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"reflect"
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"strings"
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)
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// JOSE represent a JSON Object Signing and Encryption header as
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// defined in RFC 7515.
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type JOSE struct {
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Algorithm string `json:"alg"`
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Type string `json:"typ,omitempty"`
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Content string `json:"cty,omitempty"`
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Critical string `json:"crit,omitempty"`
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JWKSetURL string `json:"jku,omitempty"`
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JSONWebKey string `json:"jwk,omitempty"`
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KeyID string `json:"kid,omitempty"`
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X509URL string `json:"x5u,omitempty"`
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X509CertificateChain string `json:"x5c,omitempty"`
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X509ThumbprintSha1 string `json:"x5t,omitempty"`
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X509ThumbprintSha256 string `json:"x5t#S256,omitempty"`
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//Sets of adfditional headers, private or public
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AdditionalHeaders map[string]interface{} `json:"-"`
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}
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// EncodeJSON encodes a JOSE header in JSON format. Not using
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// MarshallJSON tyo avoid loops
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func (j *JOSE) EncodeJSON() ([]byte, error) {
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data, err := json.Marshal(j)
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if err != nil {
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return nil, err
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}
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if len(data) == 0 || data[0] != '{' || data[len(data)-1] != '}' {
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return nil, fmt.Errorf("jws: Invalid JSON encoding: %s", data)
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}
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if len(j.AdditionalHeaders) == 0 {
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return data, nil
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}
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moreHeader, err := json.Marshal(j.AdditionalHeaders)
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if err != nil {
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return nil, err
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}
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if len(moreHeader) == 0 || moreHeader[0] != '{' || moreHeader[len(moreHeader)-1] != '}' {
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return nil, fmt.Errorf("jws: Invalid JSON encoding: %s", data)
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}
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data[len(data)-1] = ','
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return append(data, moreHeader[1:]...), nil
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}
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// EncodeBase64 encodes a JOSE into JSON base64 string. will allocate
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// buffer.
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func (j *JOSE) EncodeBase64() ([]byte, error) {
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dec, err := j.EncodeJSON()
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if err != nil {
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return nil, err
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}
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enc := make([]byte, Base64EncodedBufferLen(len(dec)))
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base64.URLEncoding.Encode(enc, dec)
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return enc[:Base64EncodedStrippedLen(len(dec))], nil
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}
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// DecodeJOSE a JOSE header from a base64 text as defined in the RFC 7515
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func DecodeJOSE(data []byte) (*JOSE, error) {
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bData := make([]byte, Base64DecodedLenFromStripped(len(data)))
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if err := Base64Decode(bData, data); err != nil {
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return nil, err
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}
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j := &JOSE{}
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if err := json.NewDecoder(bytes.NewBuffer(bData)).Decode(j); err != nil {
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return nil, err
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}
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return j, nil
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}
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// Validate validates a JOSE header data. Maybe it should disappear
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func (j *JOSE) Validate() error {
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if len(j.Algorithm) == 0 {
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return fmt.Errorf("jwt: missing 'alg' header")
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}
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return nil
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}
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type fieldSetter func(*JOSE, string)
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var fieldSetters = make(map[string]fieldSetter)
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// UnmarshalJSON is here to satisfy interface json.Unmarshaller. We
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// need to provide ou own unmarshaller for the additional header.
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func (j *JOSE) UnmarshalJSON(b []byte) error {
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raw := make(map[string]interface{})
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if err := json.Unmarshal(b, &raw); err != nil {
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return err
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}
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if j.AdditionalHeaders == nil {
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j.AdditionalHeaders = make(map[string]interface{}, len(raw))
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}
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for key, data := range raw {
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if fSetter, ok := fieldSetters[key]; ok == true {
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strData, ok := data.(string)
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if ok == false {
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return &json.UnmarshalTypeError{
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Value: reflect.TypeOf(data).Kind().String(),
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Type: reflect.TypeOf(string("")),
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}
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}
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fSetter(j, strData)
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continue
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}
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j.AdditionalHeaders[key] = data
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}
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return nil
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}
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func init() {
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tJOSE := reflect.TypeOf(JOSE{})
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for i := 0; i < tJOSE.NumField(); i++ {
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jField := tJOSE.Field(i)
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jTag := jField.Tag.Get("json")
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if len(jTag) == 0 || jTag == "-" {
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continue
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}
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jName := strings.Split(jTag, ",")
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fieldSetters[jName[0]] = func(j *JOSE, data string) {
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reflect.ValueOf(j).Elem().FieldByName(jField.Name).SetString(data)
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}
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}
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}
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