Add Viessmann (#20111)

plugin/auth/viessmann.go

@@ -0,0 +1,115 @@
+package auth
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/cookiejar"
+	"net/url"
+
+	"github.com/evcc-io/evcc/util"
+	"github.com/evcc-io/evcc/util/request"
+	"github.com/evcc-io/evcc/util/transport"
+	"github.com/samber/lo"
+	"golang.org/x/oauth2"
+)
+
+const (
+	OAuthURI    = "https://iam.viessmann.com/idp/v3"
+	RedirectURI = "http://localhost:4200/"
+	// ^ the value of RedirectURI doesn't matter, but it must be the same between requests
+)
+
+func OAuth2Config(clientID string) *oauth2.Config {
+	return &oauth2.Config{
+		ClientID: clientID,
+		Endpoint: oauth2.Endpoint{
+			AuthURL:   OAuthURI + "/authorize",
+			TokenURL:  OAuthURI + "/token",
+			AuthStyle: oauth2.AuthStyleInHeader,
+		},
+		RedirectURL: RedirectURI,
+		Scopes:      []string{"IoT User", "offline_access"},
+	}
+}
+
+func init() {
+	registry.AddCtx("viessmann", NewViessmannFromConfig)
+}
+
+type Viessmann struct {
+	client *http.Client
+	ts     oauth2.TokenSource
+}
+
+func NewViessmannFromConfig(ctx context.Context, other map[string]any) (Authorizer, error) {
+	var cc struct {
+		ClientID       string
+		User, Password string
+	}
+	if err := util.DecodeOther(other, &cc); err != nil {
+		return nil, err
+	}
+
+	v := &Viessmann{
+		client: request.NewClient(util.NewLogger("viessmann")),
+	}
+
+	oc := OAuth2Config(cc.ClientID)
+
+	ctx = context.WithValue(context.Background(), oauth2.HTTPClient, v.client)
+	token, err := v.login(ctx, oc, cc.User, cc.Password)
+	if err != nil {
+		return nil, err
+	}
+
+	v.ts = oc.TokenSource(ctx, token)
+
+	return v, nil
+}
+
+func (v *Viessmann) Transport(base http.RoundTripper) (http.RoundTripper, error) {
+	return &oauth2.Transport{
+		Base:   base,
+		Source: v.ts,
+	}, nil
+}
+
+func (v *Viessmann) login(ctx context.Context, oc *oauth2.Config, user, password string) (*oauth2.Token, error) {
+	cv := oauth2.GenerateVerifier()
+
+	state := lo.RandomString(16, lo.AlphanumericCharset)
+	uri := oc.AuthCodeURL(state, oauth2.S256ChallengeOption(cv))
+
+	v.client.Jar, _ = cookiejar.New(nil)
+	v.client.CheckRedirect = request.DontFollow
+	defer func() {
+		v.client.Jar = nil
+		v.client.CheckRedirect = nil
+	}()
+
+	req, _ := request.New(http.MethodGet, uri, nil, map[string]string{
+		"Authorization": transport.BasicAuthHeader(user, password),
+	})
+
+	resp, err := v.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusFound {
+		return nil, fmt.Errorf("unexpected status %d", resp.StatusCode)
+	}
+
+	loc, err := url.Parse(resp.Header.Get("Location"))
+	if err != nil {
+		return nil, err
+	}
+	code := loc.Query().Get("code")
+
+	ctx, cancel := context.WithTimeout(ctx, request.Timeout)
+	defer cancel()
+
+	return oc.Exchange(ctx, code, oauth2.VerifierOption(cv))
+}