Assemble submit URL

userapi/api/api.go

@@ -475,6 +475,14 @@ func (t ThreepidSessionType) Name() string {
 	}[t]
 }
 
+func (t ThreepidSessionType) SubmitPath() string {
+	return [...]string{
+		"/_matrix/client/r0/account/password/email/submitToken",
+		"/_matrix/client/r0/account/3pid/email/submitToken",
+		"/_matrix/client/r0/register/email/submitToken",
+	}[t]
+}
+
 func ThreepidSessionTypes() []ThreepidSessionType {
 	return []ThreepidSessionType{
 		AccountPassword,

userapi/internal/threepid.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+	"net/url"
 	"time"
 
 	"github.com/matrix-org/dendrite/internal"
@@ -58,11 +59,22 @@ func (a *UserInternalAPI) CreateSession(ctx context.Context, req *api.CreateSess
 		}
 	}
 	res.Sid = s.Sid
+	query := url.Values{
+		"sid":           []string{s.Sid},
+		"client_secret": []string{s.ClientSecret},
+		"token":         []string{s.Token},
+	}
+	link := url.URL{
+		Scheme:   "https",
+		Host:     string(a.ServerName),
+		Path:     req.SessionType.SubmitPath(),
+		RawQuery: query.Encode(),
+	}
 	// TODO - if we fail sending email, send_attempt for next requests must be bumped,
 	// otherwise we will just return nil from this function and not sent email
 	return a.Mail.Send(&mail.Mail{
 		To:    s.ThreePid,
-		Link:  s.NextLink,
+		Link:  link.String(),
 		Token: s.Token,
 		Extra: req.Extra,
 	}, req.SessionType)

userapi/userapi_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	"net/url"
 	"reflect"
 	"testing"
 
@@ -238,6 +239,14 @@ func mustCreateSession(is *is.I, i *internal.UserInternalAPI) (resp *api.CreateS
 	sub := <-mailer.c[api.AccountPassword]
 	is.Equal(len(sub.Token), 64)
 	is.Equal(sub.To, testReq.ThreePid)
+	submitUrl, err := url.Parse(sub.Link)
+	is.NoErr(err)
+	is.Equal(submitUrl.Host, "example.com")
+	is.Equal(submitUrl.Path, "/_matrix/client/r0/account/password/email/submitToken")
+	q := submitUrl.Query()
+	is.Equal(len(q["sid"][0]), 43)
+	is.Equal(q["token"][0], sub.Token)
+	is.Equal(q["client_secret"][0], "foobar")
 	token = sub.Token
 	return
 }