Additional OAuth2 providers (#1010)

* add google+

* sort signin oauth2 providers based on the name so order is always the same

* update auth tip for google+

* add gitlab provider

* add bitbucket provider (and some go fmt)

* add twitter provider

* add facebook provider

* add dropbox provider

* add openid connect provider incl. new format of tips section in "Add New Source"

* lower the amount of disk storage for each session to prevent issues while building cross platform (and disk overflow)

* imports according to goimport and code style

* make it possible to set custom urls to gitlab and github provider (only these could have a different host)

* split up oauth2 into multiple files

* small typo in comment

* fix indention

* fix indentation

* fix new line before external import

* fix layout of signin part

* update "broken" dependency

vendor/github.com/mrjones/oauth/provider.go

@@ -0,0 +1,163 @@
+package oauth
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+//
+// OAuth1 2-legged provider
+// Contributed by https://github.com/jacobpgallagher
+//
+
+// Provide an buffer reader which implements the Close() interface
+type oauthBufferReader struct {
+	*bytes.Buffer
+}
+
+// So that it implements the io.ReadCloser interface
+func (m oauthBufferReader) Close() error { return nil }
+
+type ConsumerGetter func(key string, header map[string]string) (*Consumer, error)
+
+// Provider provides methods for a 2-legged Oauth1 provider
+type Provider struct {
+	ConsumerGetter ConsumerGetter
+
+	// For mocking
+	clock clock
+}
+
+// NewProvider takes a function to get the consumer secret from a datastore.
+// Returns a Provider
+func NewProvider(secretGetter ConsumerGetter) *Provider {
+	provider := &Provider{
+		secretGetter,
+		&defaultClock{},
+	}
+	return provider
+}
+
+// Combine a URL and Request to make the URL absolute
+func makeURLAbs(url *url.URL, request *http.Request) {
+	if !url.IsAbs() {
+		url.Host = request.Host
+		if request.TLS != nil || request.Header.Get("X-Forwarded-Proto") == "https" {
+			url.Scheme = "https"
+		} else {
+			url.Scheme = "http"
+		}
+	}
+}
+
+// IsAuthorized takes an *http.Request and returns a pointer to a string containing the consumer key,
+// or nil if not authorized
+func (provider *Provider) IsAuthorized(request *http.Request) (*string, error) {
+	var err error
+	var userParams map[string]string
+
+	// start with the body/query params
+	userParams, err = parseBody(request)
+	if err != nil {
+		return nil, err
+	}
+
+	// if the oauth params are in the Authorization header, grab them, and
+	// let them override what's in userParams
+	authHeader := request.Header.Get(HTTP_AUTH_HEADER)
+	if len(authHeader) > 6 && strings.EqualFold(OAUTH_HEADER, authHeader[0:6]) {
+		authHeader = authHeader[6:]
+		params := strings.Split(authHeader, ",")
+		for _, param := range params {
+			vals := strings.SplitN(param, "=", 2)
+			k := strings.Trim(vals[0], " ")
+			v := strings.Trim(strings.Trim(vals[1], "\""), " ")
+			if strings.HasPrefix(k, "oauth") {
+				userParams[k], err = url.QueryUnescape(v)
+				if err != nil {
+					return nil, err
+				}
+			}
+		}
+	}
+
+	// pop the request's signature, it's not included in our signature
+	// calculation
+	oauthSignature, ok := userParams[SIGNATURE_PARAM]
+	if !ok {
+		return nil, fmt.Errorf("no oauth signature")
+	}
+	delete(userParams, SIGNATURE_PARAM)
+
+	// get the oauth consumer key
+	consumerKey, ok := userParams[CONSUMER_KEY_PARAM]
+	if !ok || consumerKey == "" {
+		return nil, fmt.Errorf("no consumer key")
+	}
+
+	// use it to create a consumer object
+	consumer, err := provider.ConsumerGetter(consumerKey, userParams)
+	if err != nil {
+		return nil, err
+	}
+
+	// Make sure timestamp is no more than 10 digits
+	timestamp := userParams[TIMESTAMP_PARAM]
+	if len(timestamp) > 10 {
+		timestamp = timestamp[0:10]
+	}
+
+	// Check the timestamp
+	if !consumer.serviceProvider.IgnoreTimestamp {
+		oauthTimeNumber, err := strconv.Atoi(timestamp)
+		if err != nil {
+			return nil, err
+		}
+
+		if math.Abs(float64(int64(oauthTimeNumber)-provider.clock.Seconds())) > 5*60 {
+			return nil, fmt.Errorf("too much clock skew")
+		}
+	}
+
+	// Include the query string params in the base string
+	if consumer.serviceProvider.SignQueryParams {
+		for k, v := range request.URL.Query() {
+			userParams[k] = strings.Join(v, "")
+		}
+	}
+
+	// if our consumer supports bodyhash, check it
+	if consumer.serviceProvider.BodyHash {
+		bodyHash, err := calculateBodyHash(request, consumer.signer)
+		if err != nil {
+			return nil, err
+		}
+
+		sentHash, ok := userParams[BODY_HASH_PARAM]
+
+		if bodyHash == "" && ok {
+			return nil, fmt.Errorf("body_hash must not be set")
+		} else if sentHash != bodyHash {
+			return nil, fmt.Errorf("body_hash mismatch")
+		}
+	}
+
+	allParams := NewOrderedParams()
+	for key, value := range userParams {
+		allParams.Add(key, value)
+	}
+
+	makeURLAbs(request.URL, request)
+	baseString := consumer.requestString(request.Method, canonicalizeUrl(request.URL), allParams)
+	err = consumer.signer.Verify(baseString, oauthSignature)
+	if err != nil {
+		return nil, err
+	}
+
+	return &consumerKey, nil
+}