api: add github oauth

Closes https://gitlab.com/commento/commento/issues/20

api/Gopkg.lock

@@ -116,10 +116,11 @@
 
 [[projects]]
   branch = "master"
-  digest = "1:bea0314c10bd362ab623af4880d853b5bad3b63d0ab9945c47e461b8d04203ed"
+  digest = "1:82e6e4dc5ab71680d89684e4649be630fdeeaf81feb8e88e4a56273a0cd4d966"
   name = "golang.org/x/oauth2"
   packages = [
     ".",
+    "github",
     "google",
     "internal",
     "jws",
@@ -161,6 +162,7 @@
     "github.com/russross/blackfriday",
     "golang.org/x/crypto/bcrypt",
     "golang.org/x/oauth2",
+    "golang.org/x/oauth2/github",
     "golang.org/x/oauth2/google",
   ]
   solver-name = "gps-cdcl"

api/config.go

@@ -47,6 +47,9 @@ func configParse() error {
 
 		"GOOGLE_KEY":    "",
 		"GOOGLE_SECRET": "",
+
+		"GITHUB_KEY":    "",
+		"GITHUB_SECRET": "",
 	}
 
 	for key, value := range defaults {

api/oauth.go

@@ -11,5 +11,9 @@ func oauthConfigure() error {
 		return err
 	}
 
+	if err := githubOauthConfigure(); err != nil {
+		return err
+	}
+
 	return nil
 }

api/oauth_github.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/github"
+	"os"
+)
+
+var githubConfig *oauth2.Config
+
+func githubOauthConfigure() error {
+	githubConfig = nil
+	if os.Getenv("GITHUB_KEY") == "" && os.Getenv("GITHUB_SECRET") == "" {
+		return nil
+	}
+
+	if os.Getenv("GITHUB_KEY") == "" {
+		logger.Errorf("COMMENTO_GITHUB_KEY not configured, but COMMENTO_GITHUB_SECRET is set")
+		return errorOauthMisconfigured
+	}
+
+	if os.Getenv("GITHUB_SECRET") == "" {
+		logger.Errorf("COMMENTO_GITHUB_SECRET not configured, but COMMENTO_GITHUB_KEY is set")
+		return errorOauthMisconfigured
+	}
+
+	logger.Infof("loading github OAuth config")
+
+	githubConfig = &oauth2.Config{
+		RedirectURL:  os.Getenv("ORIGIN") + "/api/oauth/github/callback",
+		ClientID:     os.Getenv("GITHUB_KEY"),
+		ClientSecret: os.Getenv("GITHUB_SECRET"),
+		Scopes: []string{
+			"read:user",
+			"user:email",
+		},
+		Endpoint: github.Endpoint,
+	}
+
+	configuredOauths = append(configuredOauths, "github")
+
+	return nil
+}

api/oauth_github_callback.go

@@ -0,0 +1,115 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"golang.org/x/oauth2"
+	"io/ioutil"
+	"net/http"
+)
+
+func githubGetPrimaryEmail(accessToken string) (string, error) {
+	resp, err := http.Get("https://api.github.com/user/emails?access_token=" + accessToken)
+	defer resp.Body.Close()
+
+	contents, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "",  errorCannotReadResponse
+	}
+
+	user := []map[string]interface{}{}
+	if err := json.Unmarshal(contents, &user); err != nil {
+		logger.Errorf("error unmarshaling github user: %v", err)
+		return "", errorInternal
+	}
+
+	nonPrimaryEmail := ""
+	for _, email := range(user) {
+		nonPrimaryEmail = email["email"].(string)
+		if email["primary"].(bool) {
+			return email["email"].(string), nil
+		}
+	}
+
+	return nonPrimaryEmail, nil
+}
+
+func githubCallbackHandler(w http.ResponseWriter, r *http.Request) {
+	commenterToken := r.FormValue("state")
+	code := r.FormValue("code")
+
+	_, err := commenterGetByCommenterToken(commenterToken)
+	if err != nil && err != errorNoSuchToken {
+		fmt.Fprintf(w, "Error: %s\n", err.Error())
+		return
+	}
+
+	token, err := githubConfig.Exchange(oauth2.NoContext, code)
+	if err != nil {
+		fmt.Fprintf(w, "Error: %s", err.Error())
+		return
+	}
+
+	email, err := githubGetPrimaryEmail(token.AccessToken)
+	if err != nil {
+		fmt.Fprintf(w, "Error: %s", err.Error())
+		return
+	}
+
+	resp, err := http.Get("https://api.github.com/user?access_token=" + token.AccessToken)
+	defer resp.Body.Close()
+
+	contents, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		fmt.Fprintf(w, "Error: %s", errorCannotReadResponse.Error())
+		return
+	}
+
+	user := make(map[string]interface{})
+	if err := json.Unmarshal(contents, &user); err != nil {
+		fmt.Fprintf(w, "Error: %s", errorInternal.Error())
+		return
+	}
+
+	if email == "" {
+		if user["email"] == nil {
+			fmt.Fprintf(w, "Error: no email address returned by Github")
+			return
+		}
+
+		email = user["email"].(string)
+	}
+
+	c, err := commenterGetByEmail("github", email)
+	if err != nil && err != errorNoSuchCommenter {
+		fmt.Fprintf(w, "Error: %s", err.Error())
+		return
+	}
+
+	var commenterHex string
+
+	// TODO: in case of returning users, update the information we have on record?
+	if err == errorNoSuchCommenter {
+		var link string
+		if val, ok := user["html_url"]; ok {
+			link = val.(string)
+		} else {
+			link = "undefined"
+		}
+
+		commenterHex, err = commenterNew(email, user["name"].(string), link, user["avatar_url"].(string), "github", "")
+		if err != nil {
+			fmt.Fprintf(w, "Error: %s", err.Error())
+			return
+		}
+	} else {
+		commenterHex = c.CommenterHex
+	}
+
+	if err := commenterSessionUpdate(commenterToken, commenterHex); err != nil {
+		fmt.Fprintf(w, "Error: %s", err.Error())
+		return
+	}
+
+	fmt.Fprintf(w, "<html><script>window.parent.close()</script></html>")
+}

api/oauth_github_redirect.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func githubRedirectHandler(w http.ResponseWriter, r *http.Request) {
+	if githubConfig == nil {
+		logger.Errorf("github oauth access attempt without configuration")
+		fmt.Fprintf(w, "error: this website has not configured github OAuth")
+		return
+	}
+
+	commenterToken := r.FormValue("commenterToken")
+
+	_, err := commenterGetByCommenterToken(commenterToken)
+	if err != nil && err != errorNoSuchToken {
+		fmt.Fprintf(w, "error: %s\n", err.Error())
+		return
+	}
+
+	url := githubConfig.AuthCodeURL(commenterToken)
+	http.Redirect(w, r, url, http.StatusFound)
+}

api/router_api.go

@@ -29,6 +29,9 @@ func apiRouterInit(router *mux.Router) error {
 	router.HandleFunc("/api/oauth/google/redirect", googleRedirectHandler).Methods("GET")
 	router.HandleFunc("/api/oauth/google/callback", googleCallbackHandler).Methods("GET")
 
+	router.HandleFunc("/api/oauth/github/redirect", githubRedirectHandler).Methods("GET")
+	router.HandleFunc("/api/oauth/github/callback", githubCallbackHandler).Methods("GET")
+
 	router.HandleFunc("/api/comment/new", commentNewHandler).Methods("POST")
 	router.HandleFunc("/api/comment/list", commentListHandler).Methods("POST")
 	router.HandleFunc("/api/comment/count", commentCountHandler).Methods("POST")

frontend/js/commento.js

@@ -269,6 +269,8 @@
         avatar = create("img");
         if (resp.commenter.provider === "google") {
           attrSet(avatar, "src", resp.commenter.photo + "?sz=50");
+        } else if (resp.commenter.provider === "github") {
+          attrSet(avatar, "src", resp.commenter.photo + "&s=50");
         } else {
           attrSet(avatar, "src", resp.commenter.photo);
         }
@@ -699,6 +701,8 @@
         avatar = create("img");
         if (commenter.provider === "google") {
           attrSet(avatar, "src", commenter.photo + "?sz=50");
+        } else if (commenter.provider === "github") {
+          attrSet(avatar, "src", commenter.photo + "&s=50");
         } else {
           attrSet(avatar, "src", commenter.photo);
         }