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bitbucket.go
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bitbucket.go
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package api
import (
"bytes"
"compress/gzip"
"context"
"encoding/json"
"errors"
"io"
"io/ioutil"
"net/http"
"net/http/httputil"
"net/url"
"regexp"
"strings"
"sync"
"golang.org/x/oauth2"
"golang.org/x/oauth2/bitbucket"
)
type BitBucketGateway struct {
proxy *httputil.ReverseProxy
}
func NewBitBucketGateway() *BitBucketGateway {
return &BitBucketGateway{
proxy: &httputil.ReverseProxy{
Director: bitbucketDirector,
Transport: &BitBucketTransport{},
},
}
}
var bitbucketPathRegexp = regexp.MustCompile("^/bitbucket/?")
var bitbucketAllowedRegexp = regexp.MustCompile("^/bitbucket/src/?")
var bitbucketTokenExpirationMessageRegexp = regexp.MustCompile("(?i)^access token expired")
var currentAccessToken *oauth2.Token
type notifyRefreshTokenSource struct {
new oauth2.TokenSource
mu sync.Mutex // guards t
t *oauth2.Token
}
func (s *notifyRefreshTokenSource) Token() (*oauth2.Token, error) {
s.mu.Lock()
defer s.mu.Unlock()
if s.t.Valid() {
return s.t, nil
}
t, err := s.new.Token()
if err != nil {
return nil, err
}
s.t = t
return t, nil
}
var currentTokenSource *notifyRefreshTokenSource
func getTokenSource(ctx context.Context) *notifyRefreshTokenSource {
config := getConfig(ctx)
if currentTokenSource != nil {
return currentTokenSource
}
blankToken := &oauth2.Token{
AccessToken: "",
RefreshToken: config.BitBucket.RefreshToken,
}
oauthConfig := &oauth2.Config{
ClientID: config.BitBucket.ClientID,
ClientSecret: config.BitBucket.ClientSecret,
Endpoint: bitbucket.Endpoint,
}
tokenSource := ¬ifyRefreshTokenSource{
new: oauthConfig.TokenSource(ctx, blankToken),
t: blankToken,
}
currentTokenSource = tokenSource
return tokenSource
}
func bitbucketDirector(r *http.Request) {
ctx := r.Context()
target := getProxyTarget(ctx)
accessToken := getAccessToken(ctx)
targetQuery := target.RawQuery
r.Host = target.Host
r.URL.Scheme = target.Scheme
r.URL.Host = target.Host
r.URL.Path = singleJoiningSlash(target.Path, bitbucketPathRegexp.ReplaceAllString(r.URL.Path, "/"))
if targetQuery == "" || r.URL.RawQuery == "" {
r.URL.RawQuery = targetQuery + r.URL.RawQuery
} else {
r.URL.RawQuery = targetQuery + "&" + r.URL.RawQuery
}
if _, ok := r.Header["User-Agent"]; !ok {
r.Header.Set("User-Agent", "")
}
if r.Method != http.MethodOptions {
r.Header.Set("Authorization", "Bearer "+accessToken)
}
log := getLogEntry(r)
log.Infof("Proxying to BitBucket: %v", r.URL.String(), r.Header.Get("Authorization"))
}
func (bb *BitBucketGateway) ServeHTTP(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
config := getConfig(ctx)
if config == nil || config.BitBucket.RefreshToken == "" {
handleError(notFoundError("No BitBucket Settings Configured"), w, r)
return
}
if err := bb.authenticate(w, r); err != nil {
handleError(unauthorizedError(err.Error()), w, r)
return
}
endpoint := config.BitBucket.Endpoint
apiURL := singleJoiningSlash(endpoint, "/repositories/"+config.BitBucket.Repo)
target, err := url.Parse(apiURL)
if err != nil {
handleError(internalServerError("Unable to process BitBucket endpoint"), w, r)
return
}
tokenSource := getTokenSource(ctx)
token, err := tokenSource.Token()
if err != nil {
handleError(internalServerError("Unable to process BitBucket endpoint"), w, r)
}
ctx = withProxyTarget(ctx, target)
ctx = withAccessToken(ctx, token.AccessToken)
bb.proxy.ServeHTTP(w, r.WithContext(ctx))
}
func (bb *BitBucketGateway) authenticate(w http.ResponseWriter, r *http.Request) error {
ctx := r.Context()
claims := getClaims(ctx)
config := getConfig(ctx)
if claims == nil {
return errors.New("Access to endpoint not allowed: no claims found in Bearer token")
}
if !bitbucketAllowedRegexp.MatchString(r.URL.Path) {
return errors.New("Access to endpoint not allowed: this part of BitBucket's API has been restricted")
}
if len(config.Roles) == 0 {
return nil
}
roles, ok := claims.AppMetaData["roles"]
if ok {
roleStrings, _ := roles.([]interface{})
for _, data := range roleStrings {
role, _ := data.(string)
for _, adminRole := range config.Roles {
if role == adminRole {
return nil
}
}
}
}
return errors.New("Access to endpoint not allowed: your role doesn't allow access")
}
func rewriteBitBucketLink(link, endpointAPIURL, proxyAPIURL string) string {
return proxyAPIURL + strings.TrimPrefix(link, endpointAPIURL)
}
func rewriteLinksInBitBucketResponse(resp *http.Response, endpointAPIURL, proxyAPIURL string) error {
var bodyReader io.ReadCloser
var err error
switch resp.Header.Get("Content-Encoding") {
case "gzip":
bodyReader, err = gzip.NewReader(resp.Body)
if err != nil {
return nil
}
defer bodyReader.Close()
default:
bodyReader = resp.Body
}
body, err := ioutil.ReadAll(bodyReader)
if err != nil {
return nil
}
var b map[string]interface{}
if err := json.Unmarshal(body, &b); err != nil {
return nil
}
if next, ok := b["next"].(string); ok {
b["next"] = rewriteBitBucketLink(next, endpointAPIURL, proxyAPIURL)
}
if prev, ok := b["previous"].(string); ok {
b["previous"] = rewriteBitBucketLink(prev, endpointAPIURL, proxyAPIURL)
}
newBodyBytes, err := json.Marshal(b)
switch resp.Header.Get("Content-Encoding") {
case "gzip":
var compressedBody bytes.Buffer
w := gzip.NewWriter(&compressedBody)
defer w.Close()
_, err = w.Write(newBodyBytes)
if err != nil {
return err
}
resp.Body = ioutil.NopCloser(&compressedBody)
default:
resp.Body = ioutil.NopCloser(bytes.NewReader(newBodyBytes))
}
return nil
}
type BitBucketTransport struct{}
func (t *BitBucketTransport) RoundTrip(r *http.Request) (*http.Response, error) {
ctx := r.Context()
config := getConfig(ctx)
resp, err := http.DefaultTransport.RoundTrip(r)
if err != nil {
return resp, err
}
// remove CORS headers from BitBucket and use our own
resp.Header.Del("Access-Control-Allow-Origin")
if strings.HasPrefix(resp.Header.Get("Content-Type"), "application/json") {
repo := config.BitBucket.Repo
apiURL := singleJoiningSlash(config.BitBucket.Endpoint, "/repositories/"+repo)
err = rewriteLinksInBitBucketResponse(resp, apiURL, "")
if err != nil {
return resp, err
}
}
return resp, nil
}