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|
package challenge
import (
"fmt"
"net/http"
"net/url"
"strings"
"sync"
)
// Challenge carries information from a WWW-Authenticate response header.
// See RFC 2617.
type Challenge struct {
// Scheme is the auth-scheme according to RFC 2617
Scheme string
// Parameters are the auth-params according to RFC 2617
Parameters map[string]string
}
// Manager manages the challenges for endpoints.
// The challenges are pulled out of HTTP responses. Only
// responses which expect challenges should be added to
// the manager, since a non-unauthorized request will be
// viewed as not requiring challenges.
type Manager interface {
// GetChallenges returns the challenges for the given
// endpoint URL.
GetChallenges(endpoint url.URL) ([]Challenge, error)
// AddResponse adds the response to the challenge
// manager. The challenges will be parsed out of
// the WWW-Authenicate headers and added to the
// URL which was produced the response. If the
// response was authorized, any challenges for the
// endpoint will be cleared.
AddResponse(resp *http.Response) error
}
// NewSimpleManager returns an instance of
// Manger which only maps endpoints to challenges
// based on the responses which have been added the
// manager. The simple manager will make no attempt to
// perform requests on the endpoints or cache the responses
// to a backend.
func NewSimpleManager() Manager {
return &simpleManager{
Challanges: make(map[string][]Challenge),
}
}
type simpleManager struct {
sync.RWMutex
Challanges map[string][]Challenge
}
func normalizeURL(endpoint *url.URL) {
endpoint.Host = strings.ToLower(endpoint.Host)
endpoint.Host = canonicalAddr(endpoint)
}
func (m *simpleManager) GetChallenges(endpoint url.URL) ([]Challenge, error) {
normalizeURL(&endpoint)
m.RLock()
defer m.RUnlock()
challenges := m.Challanges[endpoint.String()]
return challenges, nil
}
func (m *simpleManager) AddResponse(resp *http.Response) error {
challenges := ResponseChallenges(resp)
if resp.Request == nil {
return fmt.Errorf("missing request reference")
}
urlCopy := url.URL{
Path: resp.Request.URL.Path,
Host: resp.Request.URL.Host,
Scheme: resp.Request.URL.Scheme,
}
normalizeURL(&urlCopy)
m.Lock()
defer m.Unlock()
m.Challanges[urlCopy.String()] = challenges
return nil
}
// Octet types from RFC 2616.
type octetType byte
var octetTypes [256]octetType
const (
isToken octetType = 1 << iota
isSpace
)
func init() {
// OCTET = <any 8-bit sequence of data>
// CHAR = <any US-ASCII character (octets 0 - 127)>
// CTL = <any US-ASCII control character (octets 0 - 31) and DEL (127)>
// CR = <US-ASCII CR, carriage return (13)>
// LF = <US-ASCII LF, linefeed (10)>
// SP = <US-ASCII SP, space (32)>
// HT = <US-ASCII HT, horizontal-tab (9)>
// <"> = <US-ASCII double-quote mark (34)>
// CRLF = CR LF
// LWS = [CRLF] 1*( SP | HT )
// TEXT = <any OCTET except CTLs, but including LWS>
// separators = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" | "\" | <">
// | "/" | "[" | "]" | "?" | "=" | "{" | "}" | SP | HT
// token = 1*<any CHAR except CTLs or separators>
// qdtext = <any TEXT except <">>
for c := 0; c < 256; c++ {
var t octetType
isCtl := c <= 31 || c == 127
isChar := 0 <= c && c <= 127
isSeparator := strings.IndexRune(" \t\"(),/:;<=>?@[]\\{}", rune(c)) >= 0
if strings.IndexRune(" \t\r\n", rune(c)) >= 0 {
t |= isSpace
}
if isChar && !isCtl && !isSeparator {
t |= isToken
}
octetTypes[c] = t
}
}
// ResponseChallenges returns a list of authorization challenges
// for the given http Response. Challenges are only checked if
// the response status code was a 401.
func ResponseChallenges(resp *http.Response) []Challenge {
if resp.StatusCode == http.StatusUnauthorized {
// Parse the WWW-Authenticate Header and store the challenges
// on this endpoint object.
return parseAuthHeader(resp.Header)
}
return nil
}
func parseAuthHeader(header http.Header) []Challenge {
challenges := []Challenge{}
for _, h := range header[http.CanonicalHeaderKey("WWW-Authenticate")] {
v, p := parseValueAndParams(h)
if v != "" {
challenges = append(challenges, Challenge{Scheme: v, Parameters: p})
}
}
return challenges
}
func parseValueAndParams(header string) (value string, params map[string]string) {
params = make(map[string]string)
value, s := expectToken(header)
if value == "" {
return
}
value = strings.ToLower(value)
s = "," + skipSpace(s)
for strings.HasPrefix(s, ",") {
var pkey string
pkey, s = expectToken(skipSpace(s[1:]))
if pkey == "" {
return
}
if !strings.HasPrefix(s, "=") {
return
}
var pvalue string
pvalue, s = expectTokenOrQuoted(s[1:])
if pvalue == "" {
return
}
pkey = strings.ToLower(pkey)
params[pkey] = pvalue
s = skipSpace(s)
}
return
}
func skipSpace(s string) (rest string) {
i := 0
for ; i < len(s); i++ {
if octetTypes[s[i]]&isSpace == 0 {
break
}
}
return s[i:]
}
func expectToken(s string) (token, rest string) {
i := 0
for ; i < len(s); i++ {
if octetTypes[s[i]]&isToken == 0 {
break
}
}
return s[:i], s[i:]
}
func expectTokenOrQuoted(s string) (value string, rest string) {
if !strings.HasPrefix(s, "\"") {
return expectToken(s)
}
s = s[1:]
for i := 0; i < len(s); i++ {
switch s[i] {
case '"':
return s[:i], s[i+1:]
case '\\':
p := make([]byte, len(s)-1)
j := copy(p, s[:i])
escape := true
for i = i + 1; i < len(s); i++ {
b := s[i]
switch {
case escape:
escape = false
p[j] = b
j++
case b == '\\':
escape = true
case b == '"':
return string(p[:j]), s[i+1:]
default:
p[j] = b
j++
}
}
return "", ""
}
}
return "", ""
}
|
