writefreely/oauth.go

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package writefreely
import (
"context"
"encoding/json"
"fmt"
"github.com/gorilla/sessions"
"github.com/guregu/null/zero"
"github.com/writeas/nerds/store"
"github.com/writeas/web-core/auth"
"github.com/writeas/web-core/log"
"github.com/writeas/writefreely/config"
"io"
"io/ioutil"
"net/http"
"net/url"
"strings"
"time"
)
// TokenResponse contains data returned when a token is created either
// through a code exchange or using a refresh token.
type TokenResponse struct {
AccessToken string `json:"access_token"`
ExpiresIn int `json:"expires_in"`
RefreshToken string `json:"refresh_token"`
TokenType string `json:"token_type"`
}
// InspectResponse contains data returned when an access token is inspected.
type InspectResponse struct {
ClientID string `json:"client_id"`
UserID int64 `json:"user_id"`
ExpiresAt time.Time `json:"expires_at"`
Username string `json:"username"`
Email string `json:"email"`
}
// tokenRequestMaxLen is the most bytes that we'll read from the /oauth/token
// endpoint. One megabyte is plenty.
const tokenRequestMaxLen = 1000000
// infoRequestMaxLen is the most bytes that we'll read from the
// /oauth/inspect endpoint.
const infoRequestMaxLen = 1000000
// OAuthDatastoreProvider provides a minimal interface of data store, config,
// and session store for use with the oauth handlers.
type OAuthDatastoreProvider interface {
DB() OAuthDatastore
Config() *config.Config
SessionStore() sessions.Store
}
// OAuthDatastore provides a minimal interface of data store methods used in
// oauth functionality.
type OAuthDatastore interface {
GenerateOAuthState(context.Context) (string, error)
ValidateOAuthState(context.Context, string) error
GetIDForRemoteUser(context.Context, int64) (int64, error)
CreateUser(*config.Config, *User, string) error
RecordRemoteUserID(context.Context, int64, int64) error
GetUserForAuthByID(int64) (*User, error)
}
type HttpClient interface {
Do(req *http.Request) (*http.Response, error)
}
type oauthHandler struct {
Config *config.Config
DB OAuthDatastore
Store sessions.Store
HttpClient HttpClient
}
// buildAuthURL returns a URL used to initiate authentication.
func buildAuthURL(db OAuthDatastore, ctx context.Context, clientID, authLocation, callbackURL string) (string, error) {
state, err := db.GenerateOAuthState(ctx)
if err != nil {
return "", err
}
u, err := url.Parse(authLocation)
if err != nil {
return "", err
}
q := u.Query()
q.Set("client_id", clientID)
q.Set("redirect_uri", callbackURL)
q.Set("response_type", "code")
q.Set("state", state)
u.RawQuery = q.Encode()
return u.String(), nil
}
// app *App, w http.ResponseWriter, r *http.Request
func (h oauthHandler) viewOauthInit(w http.ResponseWriter, r *http.Request) {
location, err := buildAuthURL(h.DB, r.Context(), h.Config.App.OAuthClientID, h.Config.App.OAuthProviderAuthLocation, h.Config.App.OAuthClientCallbackLocation)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, "could not prepare oauth redirect url")
return
}
http.Redirect(w, r, location, http.StatusTemporaryRedirect)
}
func (h oauthHandler) viewOauthCallback(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
code := r.FormValue("code")
state := r.FormValue("state")
err := h.DB.ValidateOAuthState(ctx, state)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
return
}
tokenResponse, err := h.exchangeOauthCode(ctx, code)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
return
}
// Now that we have the access token, let's use it real quick to make sur
// it really really works.
tokenInfo, err := h.inspectOauthAccessToken(ctx, tokenResponse.AccessToken)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
return
}
localUserID, err := h.DB.GetIDForRemoteUser(ctx, tokenInfo.UserID)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
return
}
fmt.Println("local user id", localUserID)
if localUserID == -1 {
// We don't have, nor do we want, the password from the origin, so we
//create a random string. If the user needs to set a password, they
//can do so through the settings page or through the password reset
//flow.
randPass := store.Generate62RandomString(14)
hashedPass, err := auth.HashPass([]byte(randPass))
if err != nil {
log.ErrorLog.Println(err)
failOAuthRequest(w, http.StatusInternalServerError, "unable to create password hash")
return
}
newUser := &User{
Username: tokenInfo.Username,
HashedPass: hashedPass,
HasPass: true,
Email: zero.NewString("", tokenInfo.Email != ""),
Created: time.Now().Truncate(time.Second).UTC(),
}
err = h.DB.CreateUser(h.Config, newUser, newUser.Username)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
return
}
err = h.DB.RecordRemoteUserID(ctx, newUser.ID, tokenInfo.UserID)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
return
}
if err := loginOrFail(h.Store, w, r, newUser); err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
}
return
}
user, err := h.DB.GetUserForAuthByID(localUserID)
if err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
return
}
if err = loginOrFail(h.Store, w, r, user); err != nil {
failOAuthRequest(w, http.StatusInternalServerError, err.Error())
}
}
func (h oauthHandler) exchangeOauthCode(ctx context.Context, code string) (*TokenResponse, error) {
form := url.Values{}
form.Add("grant_type", "authorization_code")
form.Add("redirect_uri", h.Config.App.OAuthClientCallbackLocation)
form.Add("code", code)
req, err := http.NewRequest("POST", h.Config.App.OAuthProviderTokenLocation, 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(h.Config.App.OAuthClientID, h.Config.App.OAuthClientSecret)
resp, err := h.HttpClient.Do(req)
if err != nil {
return nil, err
}
// Nick: I like using limited readers to reduce the risk of an endpoint
// being broken or compromised.
lr := io.LimitReader(resp.Body, tokenRequestMaxLen)
body, err := ioutil.ReadAll(lr)
if err != nil {
return nil, err
}
var tokenResponse TokenResponse
err = json.Unmarshal(body, &tokenResponse)
if err != nil {
return nil, err
}
return &tokenResponse, nil
}
func (h oauthHandler) inspectOauthAccessToken(ctx context.Context, accessToken string) (*InspectResponse, error) {
req, err := http.NewRequest("GET", h.Config.App.OAuthProviderInspectLocation, 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 := h.HttpClient.Do(req)
if err != nil {
return nil, err
}
// Nick: I like using limited readers to reduce the risk of an endpoint
// being broken or compromised.
lr := io.LimitReader(resp.Body, infoRequestMaxLen)
body, err := ioutil.ReadAll(lr)
if err != nil {
return nil, err
}
var inspectResponse InspectResponse
err = json.Unmarshal(body, &inspectResponse)
if err != nil {
return nil, err
}
return &inspectResponse, nil
}
func loginOrFail(store sessions.Store, w http.ResponseWriter, r *http.Request, user *User) error {
// An error may be returned, but a valid session should always be returned.
session, _ := store.Get(r, cookieName)
session.Values[cookieUserVal] = user.Cookie()
if err := session.Save(r, w); err != nil {
fmt.Println("error saving session", err)
return err
}
http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
return nil
}
// failOAuthRequest is an HTTP handler helper that formats returned error
// messages.
func failOAuthRequest(w http.ResponseWriter, statusCode int, message string) {
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(statusCode)
err := json.NewEncoder(w).Encode(map[string]interface{}{
"error": message,
})
if err != nil {
panic(err)
}
}