Add microsoft oauth2 providers (#16544)

* Clean up oauth2 providers

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Add AzureAD, AzureADv2, MicrosoftOnline OAuth2 providers

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Apply suggestions from code review

* remove unused Scopes

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

vendor/github.com/markbates/goth/providers/azuread/azuread.go

@@ -0,0 +1,187 @@
+// Package azuread implements the OAuth2 protocol for authenticating users through AzureAD.
+// This package can be used as a reference implementation of an OAuth2 provider for Goth.
+// To use microsoft personal account use microsoftonline provider
+package azuread
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/markbates/goth"
+	"golang.org/x/oauth2"
+)
+
+const (
+	authURL          string = "https://login.microsoftonline.com/common/oauth2/authorize"
+	tokenURL         string = "https://login.microsoftonline.com/common/oauth2/token"
+	endpointProfile  string = "https://graph.windows.net/me?api-version=1.6"
+	graphAPIResource string = "https://graph.windows.net/"
+)
+
+// New creates a new AzureAD provider, and sets up important connection details.
+// You should always call `AzureAD.New` to get a new Provider. Never try to create
+// one manually.
+func New(clientKey, secret, callbackURL string, resources []string, scopes ...string) *Provider {
+	p := &Provider{
+		ClientKey:    clientKey,
+		Secret:       secret,
+		CallbackURL:  callbackURL,
+		providerName: "azuread",
+	}
+
+	p.resources = make([]string, 0, 1+len(resources))
+	p.resources = append(p.resources, graphAPIResource)
+	p.resources = append(p.resources, resources...)
+
+	p.config = newConfig(p, scopes)
+	return p
+}
+
+// Provider is the implementation of `goth.Provider` for accessing AzureAD.
+type Provider struct {
+	ClientKey    string
+	Secret       string
+	CallbackURL  string
+	HTTPClient   *http.Client
+	config       *oauth2.Config
+	providerName string
+	resources    []string
+}
+
+// Name is the name used to retrieve this provider later.
+func (p *Provider) Name() string {
+	return p.providerName
+}
+
+// SetName is to update the name of the provider (needed in case of multiple providers of 1 type)
+func (p *Provider) SetName(name string) {
+	p.providerName = name
+}
+
+// Client is HTTP client to be used in all fetch operations.
+func (p *Provider) Client() *http.Client {
+	return goth.HTTPClientWithFallBack(p.HTTPClient)
+}
+
+// Debug is a no-op for the package.
+func (p *Provider) Debug(debug bool) {}
+
+// BeginAuth asks AzureAD for an authentication end-point.
+func (p *Provider) BeginAuth(state string) (goth.Session, error) {
+	authURL := p.config.AuthCodeURL(state)
+
+	// Azure ad requires at least one resource
+	authURL += "&resource=" + url.QueryEscape(strings.Join(p.resources, " "))
+
+	return &Session{
+		AuthURL: authURL,
+	}, nil
+}
+
+// FetchUser will go to AzureAD and access basic information about the user.
+func (p *Provider) FetchUser(session goth.Session) (goth.User, error) {
+	msSession := session.(*Session)
+	user := goth.User{
+		AccessToken: msSession.AccessToken,
+		Provider:    p.Name(),
+		ExpiresAt:   msSession.ExpiresAt,
+	}
+
+	if user.AccessToken == "" {
+		return user, fmt.Errorf("%s cannot get user information without accessToken", p.providerName)
+	}
+
+	req, err := http.NewRequest("GET", endpointProfile, nil)
+	if err != nil {
+		return user, err
+	}
+
+	req.Header.Set(authorizationHeader(msSession))
+
+	response, err := p.Client().Do(req)
+	if err != nil {
+		return user, err
+	}
+	defer response.Body.Close()
+
+	if response.StatusCode != http.StatusOK {
+		return user, fmt.Errorf("%s responded with a %d trying to fetch user information", p.providerName, response.StatusCode)
+	}
+
+	err = userFromReader(response.Body, &user)
+	return user, err
+}
+
+//RefreshTokenAvailable refresh token is provided by auth provider or not
+func (p *Provider) RefreshTokenAvailable() bool {
+	return true
+}
+
+//RefreshToken get new access token based on the refresh token
+func (p *Provider) RefreshToken(refreshToken string) (*oauth2.Token, error) {
+	token := &oauth2.Token{RefreshToken: refreshToken}
+	ts := p.config.TokenSource(goth.ContextForClient(p.Client()), token)
+	newToken, err := ts.Token()
+	if err != nil {
+		return nil, err
+	}
+	return newToken, err
+}
+
+func newConfig(provider *Provider, scopes []string) *oauth2.Config {
+	c := &oauth2.Config{
+		ClientID:     provider.ClientKey,
+		ClientSecret: provider.Secret,
+		RedirectURL:  provider.CallbackURL,
+		Endpoint: oauth2.Endpoint{
+			AuthURL:  authURL,
+			TokenURL: tokenURL,
+		},
+		Scopes: []string{},
+	}
+
+	if len(scopes) > 0 {
+		for _, scope := range scopes {
+			c.Scopes = append(c.Scopes, scope)
+		}
+	} else {
+		c.Scopes = append(c.Scopes, "user_impersonation")
+	}
+
+	return c
+}
+
+func userFromReader(r io.Reader, user *goth.User) error {
+	u := struct {
+		Name              string `json:"name"`
+		Email             string `json:"mail"`
+		FirstName         string `json:"givenName"`
+		LastName          string `json:"surname"`
+		NickName          string `json:"mailNickname"`
+		UserPrincipalName string `json:"userPrincipalName"`
+		Location          string `json:"usageLocation"`
+	}{}
+
+	err := json.NewDecoder(r).Decode(&u)
+	if err != nil {
+		return err
+	}
+
+	user.Email = u.Email
+	user.Name = u.Name
+	user.FirstName = u.FirstName
+	user.LastName = u.LastName
+	user.NickName = u.Name
+	user.Location = u.Location
+	user.UserID = u.UserPrincipalName //AzureAD doesn't provide separate user_id
+
+	return nil
+}
+
+func authorizationHeader(session *Session) (string, string) {
+	return "Authorization", fmt.Sprintf("Bearer %s", session.AccessToken)
+}