add Gitlab OAuth

account.go

@@ -308,6 +308,7 @@ func viewLogin(app *App, w http.ResponseWriter, r *http.Request) error {
 		LoginUsername string
 		OauthSlack    bool
 		OauthWriteAs  bool
+		OauthGitlab   bool
 	}{
 		pageForReq(app, r),
 		r.FormValue("to"),
@@ -316,6 +317,7 @@ func viewLogin(app *App, w http.ResponseWriter, r *http.Request) error {
 		getTempInfo(app, "login-user", r, w),
 		app.Config().SlackOauth.ClientID != "",
 		app.Config().WriteAsOauth.ClientID != "",
+		app.Config().GitlabOauth.ClientID != "",
 	}
 
 	if earlyError != "" {

config/config.go

@@ -69,6 +69,16 @@ type (
 		CallbackProxyAPI string `ini:"callback_proxy_api"`
 	}
 
+	GitlabOauthCfg struct {
+		ClientID         string `ini:"client_id"`
+		ClientSecret     string `ini:"client_secret"`
+		AuthLocation     string `ini:"auth_location"`
+		TokenLocation    string `ini:"token_location"`
+		InspectLocation  string `ini:"inspect_location"`
+		CallbackProxy    string `ini:"callback_proxy"`
+		CallbackProxyAPI string `ini:"callback_proxy_api"`
+	}
+
 	SlackOauthCfg struct {
 		ClientID         string `ini:"client_id"`
 		ClientSecret     string `ini:"client_secret"`
@@ -128,6 +138,7 @@ type (
 		App          AppCfg          `ini:"app"`
 		SlackOauth   SlackOauthCfg   `ini:"oauth.slack"`
 		WriteAsOauth WriteAsOauthCfg `ini:"oauth.writeas"`
+		GitlabOauth  GitlabOauthCfg  `ini:"oauth.gitlab"`
 	}
 )
 

go.mod

@@ -21,6 +21,7 @@ require (
 	github.com/guregu/null v3.4.0+incompatible
 	github.com/hashicorp/go-multierror v1.0.0
 	github.com/ikeikeikeike/go-sitemap-generator/v2 v2.0.2
+	github.com/jteeuwen/go-bindata v3.0.7+incompatible // indirect
 	github.com/jtolds/gls v4.2.1+incompatible // indirect
 	github.com/kylemcc/twitter-text-go v0.0.0-20180726194232-7f582f6736ec
 	github.com/lunixbochs/vtclean v1.0.0 // indirect

go.sum

@@ -73,6 +73,8 @@ github.com/hashicorp/go-multierror v1.0.0 h1:iVjPR7a6H0tWELX5NxNe7bYopibicUzc7uP
 github.com/hashicorp/go-multierror v1.0.0/go.mod h1:dHtQlpGsu+cZNNAkkCN/P3hoUDHhCYQXV3UM06sGGrk=
 github.com/ikeikeikeike/go-sitemap-generator/v2 v2.0.2 h1:wIdDEle9HEy7vBPjC6oKz6ejs3Ut+jmsYvuOoAW2pSM=
 github.com/ikeikeikeike/go-sitemap-generator/v2 v2.0.2/go.mod h1:WtaVKD9TeruTED9ydiaOJU08qGoEPP/LyzTKiD3jEsw=
+github.com/jteeuwen/go-bindata v3.0.7+incompatible h1:91Uy4d9SYVr1kyTJ15wJsog+esAZZl7JmEfTkwmhJts=
+github.com/jteeuwen/go-bindata v3.0.7+incompatible/go.mod h1:JVvhzYOiGBnFSYRyV00iY8q7/0PThjIYav1p9h5dmKs=
 github.com/jtolds/gls v4.2.1+incompatible h1:fSuqC+Gmlu6l/ZYAoZzx2pyucC8Xza35fpRVWLVmUEE=
 github.com/jtolds/gls v4.2.1+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/juju/ansiterm v0.0.0-20180109212912-720a0952cc2a h1:FaWFmfWdAUKbSCtOU2QjDaorUexogfaMgbipgYATUMU=

oauth.go

@@ -165,6 +165,33 @@ func configureWriteAsOauth(parentHandler *Handler, r *mux.Router, app *App) {
 	}
 }
 
+func configureGitlabOauth(parentHandler *Handler, r *mux.Router, app *App) {
+	if app.Config().GitlabOauth.ClientID != "" {
+		callbackLocation := app.Config().App.Host + "/oauth/callback/gitlab"
+
+		var callbackProxy *callbackProxyClient = nil
+		if app.Config().GitlabOauth.CallbackProxy != "" {
+			callbackProxy = &callbackProxyClient{
+				server:           app.Config().GitlabOauth.CallbackProxyAPI,
+				callbackLocation: app.Config().App.Host + "/oauth/callback/gitlab",
+				httpClient:       config.DefaultHTTPClient(),
+			}
+			callbackLocation = app.Config().SlackOauth.CallbackProxy
+		}
+
+		oauthClient := writeAsOauthClient{
+			ClientID:         app.Config().GitlabOauth.ClientID,
+			ClientSecret:     app.Config().GitlabOauth.ClientSecret,
+			ExchangeLocation: config.OrDefaultString(app.Config().GitlabOauth.TokenLocation, writeAsExchangeLocation),
+			InspectLocation:  config.OrDefaultString(app.Config().GitlabOauth.InspectLocation, writeAsIdentityLocation),
+			AuthLocation:     config.OrDefaultString(app.Config().GitlabOauth.AuthLocation, writeAsAuthLocation),
+			HttpClient:       config.DefaultHTTPClient(),
+			CallbackLocation: callbackLocation,
+		}
+		configureOauthRoutes(parentHandler, r, app, oauthClient, callbackProxy)
+	}
+}
+
 func configureOauthRoutes(parentHandler *Handler, r *mux.Router, app *App, oauthClient oauthClient, callbackProxy *callbackProxyClient) {
 	handler := &oauthHandler{
 		Config:        app.Config(),

oauth_gitlab.go

@@ -0,0 +1,114 @@
+package writefreely
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type gitlabOauthClient struct {
+	ClientID         string
+	ClientSecret     string
+	AuthLocation     string
+	ExchangeLocation string
+	InspectLocation  string
+	CallbackLocation string
+	HttpClient       HttpClient
+}
+
+var _ oauthClient = gitlabOauthClient{}
+
+const (
+	gitlabAuthLocation     = "https://gitlab.com/oauth/authorize"
+	gitlabExchangeLocation = "https://gitlab.com/oauth/token"
+	gitlabIdentityLocation = "https://gitlab.com/oauth/inspect"
+)
+
+func (c gitlabOauthClient) GetProvider() string {
+	return "Gitlab"
+}
+
+func (c gitlabOauthClient) GetClientID() string {
+	return c.ClientID
+}
+
+func (c gitlabOauthClient) GetCallbackLocation() string {
+	return c.CallbackLocation
+}
+
+func (c gitlabOauthClient) buildLoginURL(state string) (string, error) {
+	u, err := url.Parse(c.AuthLocation)
+	if err != nil {
+		return "", err
+	}
+	q := u.Query()
+	q.Set("client_id", c.ClientID)
+	q.Set("redirect_uri", c.CallbackLocation)
+	q.Set("response_type", "code")
+	q.Set("state", state)
+	u.RawQuery = q.Encode()
+	return u.String(), nil
+}
+
+func (c gitlabOauthClient) exchangeOauthCode(ctx context.Context, code string) (*TokenResponse, error) {
+	form := url.Values{}
+	form.Add("grant_type", "authorization_code")
+	form.Add("redirect_uri", c.CallbackLocation)
+	form.Add("code", code)
+	req, err := http.NewRequest("POST", c.ExchangeLocation, strings.NewReader(form.Encode()))
+	if err != nil {
+		return nil, err
+	}
+	req.WithContext(ctx)
+	req.Header.Set("User-Agent", "writefreely")
+	req.Header.Set("Accept", "application/json")
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.SetBasicAuth(c.ClientID, c.ClientSecret)
+
+	resp, err := c.HttpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.New("unable to exchange code for access token")
+	}
+
+	var tokenResponse TokenResponse
+	if err := limitedJsonUnmarshal(resp.Body, tokenRequestMaxLen, &tokenResponse); err != nil {
+		return nil, err
+	}
+	if tokenResponse.Error != "" {
+		return nil, errors.New(tokenResponse.Error)
+	}
+	return &tokenResponse, nil
+}
+
+func (c gitlabOauthClient) inspectOauthAccessToken(ctx context.Context, accessToken string) (*InspectResponse, error) {
+	req, err := http.NewRequest("GET", c.InspectLocation, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.WithContext(ctx)
+	req.Header.Set("User-Agent", "writefreely")
+	req.Header.Set("Accept", "application/json")
+	req.Header.Set("Authorization", "Bearer "+accessToken)
+
+	resp, err := c.HttpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.New("unable to inspect access token")
+	}
+
+	var inspectResponse InspectResponse
+	if err := limitedJsonUnmarshal(resp.Body, infoRequestMaxLen, &inspectResponse); err != nil {
+		return nil, err
+	}
+	if inspectResponse.Error != "" {
+		return nil, errors.New(inspectResponse.Error)
+	}
+	return &inspectResponse, nil
+}

pages/login.tmpl

@@ -32,6 +32,10 @@ hr.short {
 	box-sizing: border-box;
 	font-size: 17px;
 }
+#gitlab-login {
+	box-sizing: border-box;
+	font-size: 17px;
+}
 </style>
 {{end}}
 {{define "content"}}
@@ -42,7 +46,7 @@ hr.short {
 		{{range .Flashes}}<li class="urgent">{{.}}</li>{{end}}
 	</ul>{{end}}
 
-	{{ if or .OauthSlack .OauthWriteAs }}
+	{{ if or .OauthSlack .OauthWriteAs .OauthGitlab }}
 		<div class="row content-container signinbtns">
 		{{ if .OauthSlack }}
 			<a class="loginbtn" href="/oauth/slack"><img alt="Sign in with Slack" height="40" width="172" src="/img/sign_in_with_slack.png" srcset="/img/sign_in_with_slack.png 1x, /img/sign_in_with_slack@2x.png 2x" /></a>
@@ -50,6 +54,9 @@ hr.short {
 		{{ if .OauthWriteAs }}
 			<a class="btn cta loginbtn" id="writeas-login" href="/oauth/write.as">Sign in with <strong>Write.as</strong></a>
 		{{ end }}
+		{{ if .OauthGitlab }}
+			<a class="btn cta loginbtn" id="gitlab-login" href="/oauth/gitlab">Sign in with <strong>GitLab</strong></a>
+		{{ end }}
 		</div>
 
 		<div class="or">

routes.go

@@ -75,6 +75,7 @@ func InitRoutes(apper Apper, r *mux.Router) *mux.Router {
 
 	configureSlackOauth(handler, write, apper.App())
 	configureWriteAsOauth(handler, write, apper.App())
+	configureGitlabOauth(handler, write, apper.App())
 
 	// Set up dyamic page handlers
 	// Handle auth