jkawamoto/roadie

//
// cloud/azure/auth/device_authorizer.go
//
// Copyright (c) 2016-2017 Junpei Kawamoto
//
// This file is part of Roadie.
//
// Roadie is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Roadie is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Roadie.  If not, see <http://www.gnu.org/licenses/>.
//

package auth

import (
    "context"
    "encoding/json"
    "fmt"
    "io"
    "net/http"
    "net/url"
    "strconv"
    "strings"
    "time"

    "github.com/Azure/go-autorest/autorest/adal"

    "golang.org/x/net/context/ctxhttp"
)

// DeviceCode defines a structure of a response to obtain a device code.
type DeviceCode struct {
    UserCode        string `json:"user_code"`
    DeviceCode      string `json:"device_code"`
    VerificationURL string `json:"verification_url"`
    ExpiresIn       string `json:"expires_in"`
    Interval        string `json:"interval"`
    Message         string `json:"message"`
}

// GetDeviceCode gets a device code.
func GetDeviceCode(ctx context.Context, clientID string) (code *DeviceCode, err error) {

    url := fmt.Sprintf(
        "https://login.microsoftonline.com/common/oauth2/devicecode?client_id=%v&resource=%v",
        clientID,
        url.QueryEscape("https://management.core.windows.net/"))
    //url.QueryEscape("00000002-0000-0000-c000-000000000000"))

    req, err := http.NewRequest("Get", url, nil)
    if err != nil {
        return
    }
    req.Header.Add("Accept", "application/json")

    res, err := ctxhttp.Do(ctx, nil, req)
    if err != nil {
        return
    }
    defer res.Body.Close()

    code = new(DeviceCode)
    err = json.NewDecoder(res.Body).Decode(&code)
    return

}

// AuthorizeDeviceCode runs authentication process by a device code.
func AuthorizeDeviceCode(ctx context.Context, clientID string, output io.Writer) (token *adal.Token, err error) {

    code, err := GetDeviceCode(ctx, clientID)
    if err != nil {
        return
    }

    io.WriteString(output, code.Message)
    io.WriteString(output, "\n")

    expire, err := strconv.Atoi(code.ExpiresIn)
    if err != nil {
        return
    }
    interval, err := strconv.Atoi(code.Interval)
    if err != nil {
        return
    }

    ctx, cancel := context.WithDeadline(ctx, time.Now().Add(time.Duration(expire-30)*time.Second))
    defer cancel()

    var req *http.Request
    var res *http.Response
    for {

        body := fmt.Sprintf(
            "resource=%v&client_id=%v&grant_type=device_code&code=%v",
            url.QueryEscape("https://management.core.windows.net/"),
            //url.QueryEscape("00000002-0000-0000-c000-000000000000"),
            clientID,
            code.DeviceCode)
        req, err = http.NewRequest("Post", "https://login.microsoftonline.com/common/oauth2/token", strings.NewReader(body))
        if err != nil {
            return
        }
        req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
        req.Header.Add("Accept", "application/json")

        res, err = ctxhttp.Do(ctx, nil, req)
        if err != nil {
            break
        }

        if res.StatusCode == 400 {
            var autherror TokenError
            err = json.NewDecoder(res.Body).Decode(&autherror)
            res.Body.Close()
            if err != nil {
                break
            }
            if strings.ToLower(autherror.ErrorSummary) != "authorization_pending" {
                break
            }

        } else {
            token = new(adal.Token)
            err = json.NewDecoder(res.Body).Decode(token)
            res.Body.Close()
            if err != nil {
                return
            }
            break
        }

        select {
        case <-ctx.Done():
            err = ctx.Err()
            break
        case <-time.After(time.Duration(interval) * time.Second):
        }

    }

    return

}