connector: implement LinkedIn connector

connector/linkedin implements authorization strategy via LinkedIn's
OAuth2 endpoint + profile API.

It doesn't implement RefreshConnector as LinkedIn doesn't provide any
refresh token at all (https://developer.linkedin.com/docs/oauth2

, Step 5
— Refresh your Access Tokens) and recommends ordinary AuthCode exchange
flow when token refresh is required.

Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>

connector/linkedin/linkedin.go

+// Package linkedin provides authentication strategies using LinkedIn
+package linkedin
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+
+	"golang.org/x/oauth2"
+
+	"github.com/coreos/dex/connector"
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	apiURL   = "https://api.linkedin.com/v1"
+	authURL  = "https://www.linkedin.com/oauth/v2/authorization"
+	tokenURL = "https://www.linkedin.com/oauth/v2/accessToken"
+)
+
+// Config holds configuration options for LinkedIn logins.
+type Config struct {
+	ClientID     string `json:"clientID"`
+	ClientSecret string `json:"clientSecret"`
+	RedirectURI  string `json:"redirectURI"`
+}
+
+// Open returns a strategy for logging in through LinkedIn
+func (c *Config) Open(id string, logger logrus.FieldLogger) (connector.Connector, error) {
+	return &linkedInConnector{
+		oauth2Config: &oauth2.Config{
+			ClientID:     c.ClientID,
+			ClientSecret: c.ClientSecret,
+			Endpoint: oauth2.Endpoint{
+				AuthURL:  authURL,
+				TokenURL: tokenURL,
+			},
+			Scopes:      []string{"r_basicprofile", "r_emailaddress"},
+			RedirectURL: c.RedirectURI,
+		},
+		logger: logger,
+	}, nil
+}
+
+type linkedInConnector struct {
+	oauth2Config *oauth2.Config
+	logger       logrus.FieldLogger
+}
+
+// LinkedIn doesn't provide refresh tokens, so we don't implement
+// RefreshConnector here.
+var (
+	_ connector.CallbackConnector = (*linkedInConnector)(nil)
+)
+
+// LoginURL returns an access token request URL
+func (c *linkedInConnector) LoginURL(scopes connector.Scopes, callbackURL, state string) (string, error) {
+	if c.oauth2Config.RedirectURL != callbackURL {
+		return "", fmt.Errorf("expected callback URL %q did not match the URL in the config %q",
+			callbackURL, c.oauth2Config.RedirectURL)
+	}
+
+	return c.oauth2Config.AuthCodeURL(state), nil
+}
+
+// HandleCallback handles HTTP redirect from LinkedIn
+func (c *linkedInConnector) HandleCallback(s connector.Scopes, r *http.Request) (identity connector.Identity, err error) {
+	q := r.URL.Query()
+	if errType := q.Get("error"); errType != "" {
+		return identity, &oauth2Error{errType, q.Get("error_description")}
+	}
+
+	ctx := r.Context()
+	token, err := c.oauth2Config.Exchange(ctx, q.Get("code"))
+	if err != nil {
+		return identity, fmt.Errorf("linkedin: get token: %v", err)
+	}
+
+	client := c.oauth2Config.Client(ctx, token)
+	profile, err := c.profile(ctx, client)
+	if err != nil {
+		return identity, fmt.Errorf("linkedin: get profile: %v", err)
+	}
+
+	identity = connector.Identity{
+		UserID:        profile.ID,
+		Username:      profile.fullname(),
+		Email:         profile.Email,
+		EmailVerified: true,
+	}
+
+	return identity, nil
+}
+
+type profile struct {
+	ID        string `json:"id"`
+	FirstName string `json:"firstName"`
+	LastName  string `json:"lastName"`
+	Email     string `json:"emailAddress"`
+}
+
+// fullname returns a full name of a person, or email if the resulting name is
+// empty
+func (p profile) fullname() string {
+	fname := strings.TrimSpace(p.FirstName + " " + p.LastName)
+	if fname == "" {
+		return p.Email
+	}
+
+	return fname
+}
+
+func (c *linkedInConnector) profile(ctx context.Context, client *http.Client) (p profile, err error) {
+	// https://developer.linkedin.com/docs/fields/basic-profile
+	req, err := http.NewRequest("GET", apiURL+"/people/~:(id,first-name,last-name,email-address)", nil)
+	if err != nil {
+		return p, fmt.Errorf("new req: %v", err)
+	}
+	q := req.URL.Query()
+	q.Add("format", "json")
+	req.URL.RawQuery = q.Encode()
+
+	resp, err := client.Do(req.WithContext(ctx))
+	if err != nil {
+		return p, fmt.Errorf("get URL %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		body, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return p, fmt.Errorf("read body: %v", err)
+		}
+		return p, fmt.Errorf("%s: %s", resp.Status, body)
+	}
+
+	if err := json.NewDecoder(resp.Body).Decode(&p); err != nil {
+		return p, fmt.Errorf("JSON decode: %v", err)
+	}
+
+	if p.Email == "" {
+		return p, fmt.Errorf("email is not set")
+	}
+
+	return p, err
+}
+
+type oauth2Error struct {
+	error            string
+	errorDescription string
+}
+
+func (e *oauth2Error) Error() string {
+	if e.errorDescription == "" {
+		return e.error
+	}
+	return e.error + ": " + e.errorDescription
+}

server/server.go

@@ -24,6 +24,7 @@ import (
 	"github.com/coreos/dex/connector/github"
 	"github.com/coreos/dex/connector/gitlab"
 	"github.com/coreos/dex/connector/ldap"
+	"github.com/coreos/dex/connector/linkedin"
 	"github.com/coreos/dex/connector/mock"
 	"github.com/coreos/dex/connector/oidc"
 	"github.com/coreos/dex/connector/saml"
@@ -409,6 +410,7 @@ var ConnectorsConfig = map[string]func() ConnectorConfig{
 	"oidc":         func() ConnectorConfig { return new(oidc.Config) },
 	"saml":         func() ConnectorConfig { return new(saml.Config) },
 	"authproxy":    func() ConnectorConfig { return new(authproxy.Config) },
+	"linkedin":     func() ConnectorConfig { return new(linkedin.Config) },
 	// Keep around for backwards compatibility.
 	"samlExperimental": func() ConnectorConfig { return new(saml.Config) },
 }

web/static/img/linkedin-icon.svg

+<?xml version="1.0" ?><svg style="enable-background:new 0 0 48 48;" version="1.1" viewBox="0 0 48 48" xml:space="preserve" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g id="Icons"><g id="Icons_3_"><g><path d="M34.9549,10.525h-21.91c-1.3899,0-2.5199,1.13-2.5199,2.52v21.91c0,1.39,1.13,2.52,2.5199,2.52     h21.91c1.3901,0,2.5201-1.13,2.5201-2.52V13.0449C37.475,11.655,36.345,10.525,34.9549,10.525z M19.415,31.335     c-0.95-0.01-1.9101-0.01-2.8701,0c-0.18,0-0.23-0.05-0.23-0.24v-10.14c0-0.19,0.06-0.24,0.24-0.24     c0.95,0.01,1.9101,0.01,2.8601,0c0.1899,0,0.24,0.06,0.23,0.24v5.08c0,1.69,0,3.3799,0.01,5.07     C19.655,31.285,19.595,31.335,19.415,31.335z M17.9849,19.3549c-1.06,0.0101-1.93-0.8799-1.93-1.9299     c0.01-1.0101,0.7801-1.92,1.9201-1.93c1.0799-0.01,1.94,0.81,1.94,1.93C19.915,18.525,19.0749,19.345,17.9849,19.3549z      M31.645,31.335h-2.81c-0.2301,0-0.24-0.01-0.24-0.25v-5.14c0-0.48-0.01-0.96-0.1501-1.43c-0.2199-0.73-0.69-1.08-1.46-1.1001     c-0.54-0.0099-1.05,0.0901-1.43,0.5101c-0.31,0.33-0.44,0.73-0.5,1.17c-0.0399,0.3899-0.07,0.79-0.07,1.19     c-0.0099,1.61-0.0099,3.22,0,4.8199c0,0.1801-0.05,0.2301-0.2199,0.2301c-0.9601-0.01-1.93-0.01-2.8901,0     c-0.1699,0-0.2299-0.05-0.2299-0.2301c0.01-3.3799,0.01-6.7699,0-10.1599c0-0.18,0.07-0.23,0.2299-0.23     c0.92,0.01,1.8401,0.01,2.7601,0c0.1799,0,0.2399,0.07,0.2299,0.24c-0.01,0.37,0,0.75,0,1.12     c0.5201-0.77,1.2201-1.26,2.1001-1.48c1.0199-0.25,2.0299-0.17,2.99,0.25c0.93,0.4,1.43,1.16,1.69,2.1     c0.18,0.61,0.26,1.24,0.27,1.88c0.0099,2.07,0.0199,4.14,0.03,6.22C31.9449,31.335,31.9449,31.335,31.645,31.335z" style="fill:#0097D3;"/></g></g></g></svg>
\ No newline at end of file

web/static/main.css

@@ -83,6 +83,11 @@ body {
   background-image: url(../static/img/saml-icon.svg);
 }
 
+.dex-btn-icon--linkedin {
+  background-image: url(../static/img/linkedin-icon.svg);
+  background-size: contain;
+}
+
 .dex-btn-text {
   font-weight: 600;
   line-height: 36px;