jwt/request/extractor.go

98 lines
3.0 KiB
Go

package request
import (
"errors"
"net/http"
"strings"
)
// Errors
var (
ErrNoTokenInRequest = errors.New("no token present in request")
)
// Extractor is an interface for extracting a token from an HTTP request.
// The ExtractToken method should return a token string or an error.
// If no token is present, you must return ErrNoTokenInRequest.
type Extractor interface {
ExtractToken(*http.Request) (string, error)
}
// HeaderExtractor is an extractor for finding a token in a header.
// Looks at each specified header in order until there's a match
type HeaderExtractor []string
func (e HeaderExtractor) ExtractToken(req *http.Request) (string, error) {
// loop over header names and return the first one that contains data
for _, header := range e {
if ah := req.Header.Get(header); ah != "" {
return ah, nil
}
}
return "", ErrNoTokenInRequest
}
// ArgumentExtractor extracts a token from request arguments. This includes a POSTed form or
// GET URL arguments. Argument names are tried in order until there's a match.
// This extractor calls `ParseMultipartForm` on the request
type ArgumentExtractor []string
func (e ArgumentExtractor) ExtractToken(req *http.Request) (string, error) {
// Make sure form is parsed. We are explicitly ignoring errors at this point
_ = req.ParseMultipartForm(10e6)
// loop over arg names and return the first one that contains data
for _, arg := range e {
if ah := req.Form.Get(arg); ah != "" {
return ah, nil
}
}
return "", ErrNoTokenInRequest
}
// MultiExtractor tries Extractors in order until one returns a token string or an error occurs
type MultiExtractor []Extractor
func (e MultiExtractor) ExtractToken(req *http.Request) (string, error) {
// loop over header names and return the first one that contains data
for _, extractor := range e {
if tok, err := extractor.ExtractToken(req); tok != "" {
return tok, nil
} else if !errors.Is(err, ErrNoTokenInRequest) {
return "", err
}
}
return "", ErrNoTokenInRequest
}
// PostExtractionFilter wraps an Extractor in this to post-process the value before it's handed off.
// See AuthorizationHeaderExtractor for an example
type PostExtractionFilter struct {
Extractor
Filter func(string) (string, error)
}
func (e *PostExtractionFilter) ExtractToken(req *http.Request) (string, error) {
if tok, err := e.Extractor.ExtractToken(req); tok != "" {
return e.Filter(tok)
} else {
return "", err
}
}
// BearerExtractor extracts a token from the Authorization header.
// The header is expected to match the format "Bearer XX", where "XX" is the
// JWT token.
type BearerExtractor struct{}
func (e BearerExtractor) ExtractToken(req *http.Request) (string, error) {
tokenHeader := req.Header.Get("Authorization")
// The usual convention is for "Bearer" to be title-cased. However, there's no
// strict rule around this, and it's best to follow the robustness principle here.
if len(tokenHeader) < 7 || !strings.EqualFold(tokenHeader[:7], "bearer ") {
return "", ErrNoTokenInRequest
}
return tokenHeader[7:], nil
}