Implement server invite codes (#37)

This introduces the ability for a YeetFile instance admin to send out
invites to a list of emails with unique signup codes. These signup
codes are tied to the email they're sent to, and are removed after a
user completes registration using that email and signup code.

The invite codes are not stored in plaintext anywhere. They are hashed
with bcrypt before storing in the database, and are only included in
plaintext in the outbound email.

Enabling invite codes requires the following conditions:

- YEETFILE_ALLOW_INVITES set to 1
- YEETFILE_SERVER_PASSWORD set to a non-empty string
- YEETFILE_EMAIL_* variables set

Author: benbusby

README.md

@@ -325,6 +325,7 @@ All environment variables can be defined in a file named `.env` at the root leve
 | YEETFILE_LIMITER_ATTEMPTS | The number of attempts to allow before rate limiting | 6 | Any number of requests |
 | YEETFILE_LOCKDOWN | Disables anonymous (not logged in) interactions | 0 | `1` to enable lockdown, `0` to allow anonymous usage |
 | YEETFILE_PROFILING | Enables server profiling on http://localhost:6060 | 0 | `1` to enable, `0` to disable (default) |
+| YEETFILE_ALLOW_INVITES | Allows the YeetFile instance admin to send unique invite codes to email addresses -- must also set `YEETFILE_SERVER_PASSWORD` and setup outgoing email (see [Misc Environment Variables](#misc-environment-variables)) | 0 | `1` to enable, `0` to disable (default) |
 
 #### Backblaze Environment Variables
 

backend/config/config.go

@@ -48,9 +48,10 @@ var (
 	TLSCert = utils.GetEnvVar("YEETFILE_TLS_CERT", "")
 	TLSKey  = utils.GetEnvVar("YEETFILE_TLS_KEY", "")
 
-	IsDebugMode   = utils.GetEnvVarBool("YEETFILE_DEBUG", false)
-	IsLockedDown  = utils.GetEnvVarBool("YEETFILE_LOCKDOWN", false)
-	InstanceAdmin = utils.GetEnvVar("YEETFILE_INSTANCE_ADMIN", "")
+	IsDebugMode    = utils.GetEnvVarBool("YEETFILE_DEBUG", false)
+	IsLockedDown   = utils.GetEnvVarBool("YEETFILE_LOCKDOWN", false)
+	InstanceAdmin  = utils.GetEnvVar("YEETFILE_INSTANCE_ADMIN", "")
+	InvitesAllowed = utils.GetEnvVarBool("YEETFILE_ALLOW_INVITES", false)
 )
 
 // =============================================================================
@@ -157,6 +158,14 @@ func init() {
 		if err != nil {
 			panic(err)
 		}
+	} else if InvitesAllowed {
+		log.Fatalf("ERROR: You must set YEETFILE_SERVER_PASSWORD if " +
+			"YEETFILE_ALLOW_INVITES is enabled.")
+	}
+
+	if InvitesAllowed && !email.Configured {
+		log.Fatal("ERROR: Email must be configured if " +
+			"YEETFILE_ALLOW_INVITES is enabled.")
 	}
 
 	if slices.Equal(secret, defaultSecret) {

backend/db/invites.go

@@ -0,0 +1,74 @@
+package db
+
+import (
+	"fmt"
+	"github.com/lib/pq"
+	"strings"
+)
+
+type Invite struct {
+	Email    string
+	Code     string
+	CodeHash []byte
+}
+
+func AddInviteCodeHashes(inviteCodes []Invite) error {
+	valueStrings := make([]string, 0, len(inviteCodes))
+	valueArgs := make([]interface{}, 0, len(inviteCodes)*2)
+
+	for i, inviteCode := range inviteCodes {
+		valueStrings = append(valueStrings, fmt.Sprintf("($%d, $%d)", i*2+1, i*2+2))
+		valueArgs = append(valueArgs, inviteCode.Email)
+		valueArgs = append(valueArgs, inviteCode.CodeHash)
+	}
+
+	stmt := fmt.Sprintf(
+		"INSERT INTO invites (email, code_hash) VALUES %s",
+		strings.Join(valueStrings, ","),
+	)
+
+	_, err := db.Exec(stmt, valueArgs...)
+	return err
+}
+
+func GetInviteCodeHash(email string) ([]byte, error) {
+	var codeHash []byte
+	s := `SELECT code_hash FROM invites WHERE email=$1`
+	err := db.QueryRow(s, email).Scan(&codeHash)
+	if err != nil {
+		return nil, err
+	}
+
+	return codeHash, nil
+}
+
+func GetInvitesList() ([]string, error) {
+	var emails []string
+	s := `SELECT email FROM invites`
+	rows, err := db.Query(s)
+	defer rows.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	for rows.Next() {
+		var email string
+		err = rows.Scan(&email)
+		if err != nil {
+			return nil, err
+		}
+		emails = append(emails, email)
+	}
+
+	return emails, nil
+}
+
+func RemoveInvites(email []string) error {
+	s := `DELETE FROM invites WHERE email=any($1)`
+	_, err := db.Exec(s, pq.Array(email))
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

backend/db/scripts/migrations/7_create_invites_table.sql

@@ -0,0 +1,7 @@
+create table if not exists invites
+(
+    email     text  not null
+        constraint invites_pk
+            primary key,
+    code_hash bytea not null
+);

backend/mail/invite.go

@@ -0,0 +1,43 @@
+package mail
+
+import (
+	"bytes"
+	"text/template"
+	"yeetfile/shared/endpoints"
+)
+
+type InviteEmail struct {
+	Code     string
+	Email    string
+	Domain   string
+	Endpoint string
+}
+
+var inviteSubject = "YeetFile Invite"
+var inviteBodyTemplate = template.Must(template.New("").Parse(
+	"Hello,\n\nYou have been invited to join a YeetFile instance at this " +
+		"domain: {{.Domain}}\n\n" +
+		"YeetFile is an open source platform that allows encrypted file " +
+		"sharing and storage.\n\n" +
+		"To create an account, you can use the following link:\n\n" +
+		"{{.Domain}}{{.Endpoint}}?email={{.Email}}&code={{.Code}}"))
+
+func SendInviteEmail(code string, to string) error {
+	var buf bytes.Buffer
+
+	inviteEmail := InviteEmail{
+		Code:     code,
+		Email:    to,
+		Domain:   smtpConfig.CallbackDomain,
+		Endpoint: string(endpoints.HTMLSignup),
+	}
+
+	err := inviteBodyTemplate.Execute(&buf, inviteEmail)
+	if err != nil {
+		return err
+	}
+
+	body := buf.String()
+	go sendEmail(to, inviteSubject, body)
+	return nil
+}

backend/server/admin/handlers.go

@@ -101,5 +101,28 @@ func FileActionHandler(w http.ResponseWriter, req *http.Request, _ string) {
 
 		_ = json.NewEncoder(w).Encode(fileInfo)
 	}
+}
+
+func InviteActionsHandler(w http.ResponseWriter, req *http.Request, _ string) {
+	var inviteAction shared.AdminInviteAction
+	err := utils.LimitedJSONReader(w, req.Body).Decode(&inviteAction)
+	if err != nil || len(inviteAction.Emails) == 0 {
+		http.Error(w, "Invalid request", http.StatusBadRequest)
+		return
+	}
 
+	switch req.Method {
+	case http.MethodPost:
+		err = createInvites(inviteAction.Emails)
+		if err != nil {
+			http.Error(w, "Error generating invites", http.StatusInternalServerError)
+			return
+		}
+	case http.MethodDelete:
+		err = deleteInvites(inviteAction.Emails)
+		if err != nil {
+			http.Error(w, "Error deleting invites", http.StatusInternalServerError)
+			return
+		}
+	}
 }

backend/server/admin/invite_actions.go

@@ -0,0 +1,53 @@
+package admin
+
+import (
+	"golang.org/x/crypto/bcrypt"
+	"log"
+	"yeetfile/backend/db"
+	"yeetfile/backend/mail"
+	"yeetfile/shared"
+)
+
+func createInvites(emails []string) error {
+	var invites []db.Invite
+	for _, email := range emails {
+		code := shared.GenRandomString(12)
+		codeHash, err := bcrypt.GenerateFromPassword([]byte(code), 8)
+		if err != nil {
+			log.Printf("Error generating invite code: %v\n", err)
+			return err
+		}
+
+		invite := db.Invite{
+			Email:    email,
+			Code:     code,
+			CodeHash: codeHash,
+		}
+
+		invites = append(invites, invite)
+	}
+
+	err := db.AddInviteCodeHashes(invites)
+	if err != nil {
+		return err
+	}
+
+	for _, invite := range invites {
+		err = mail.SendInviteEmail(invite.Code, invite.Email)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func deleteInvites(emails []string) error {
+	err := db.RemoveInvites(emails)
+	if err != nil {
+		log.Printf("Error deleting invites: %v\n", err)
+		return err
+	}
+
+	return nil
+}

backend/server/auth/handlers.go

@@ -69,10 +69,25 @@ func SignupHandler(w http.ResponseWriter, req *http.Request) {
 		err := bcrypt.CompareHashAndPassword(
 			config.YeetFileConfig.PasswordHash,
 			[]byte(signupData.ServerPassword))
+		errMsg := "Missing or invalid server password"
+
+		if err != nil && config.InvitesAllowed && len(signupData.Identifier) > 0 {
+			// Check if the provided password is an invite code
+			codeHash, dbErr := db.GetInviteCodeHash(signupData.Identifier)
+			if dbErr == nil && len(codeHash) > 0 {
+				err = bcrypt.CompareHashAndPassword(
+					codeHash,
+					[]byte(signupData.ServerPassword))
+				errMsg = "Invalid invite code"
+			}
+		}
+
 		if err != nil {
 			w.WriteHeader(http.StatusForbidden)
-			_, _ = w.Write([]byte("Missing or invalid server password"))
+			_, _ = w.Write([]byte(errMsg))
 			return
+		} else if err != nil && config.InvitesAllowed {
+
 		}
 	} else {
 		signupData.ServerPassword = "-"
@@ -247,6 +262,14 @@ func VerifyEmailHandler(w http.ResponseWriter, req *http.Request) {
 		}
 	}
 
+	// Remove invite entry
+	if config.InvitesAllowed {
+		err = db.RemoveInvites([]string{verifyEmail.Email})
+		if err != nil {
+			log.Printf("Error removing invite: %v\n", err)
+		}
+	}
+
 	// Remove verification entry
 	_ = db.DeleteVerification(verifyEmail.Email)
 	_ = session.SetSession(id, w, req)

backend/server/html/handlers.go

@@ -154,7 +154,10 @@ func DownloadPageHandler(w http.ResponseWriter, req *http.Request) {
 }
 
 // SignupPageHandler returns the HTML page for signing up for an account
-func SignupPageHandler(w http.ResponseWriter, _ *http.Request) {
+func SignupPageHandler(w http.ResponseWriter, req *http.Request) {
+	inviteEmail := req.URL.Query().Get("email")
+	inviteCode := req.URL.Query().Get("code")
+
 	_ = templates.ServeTemplate(
 		w,
 		templates.SignupHTML,
@@ -169,6 +172,8 @@ func SignupPageHandler(w http.ResponseWriter, _ *http.Request) {
 			},
 			ServerPasswordRequired: config.YeetFileConfig.PasswordHash != nil,
 			EmailConfigured:        config.YeetFileConfig.Email.Configured,
+			InviteEmail:            inviteEmail,
+			InviteCode:             inviteCode,
 		},
 	)
 }
@@ -486,6 +491,18 @@ func CheckoutCompleteHandler(w http.ResponseWriter, req *http.Request) {
 }
 
 func AdminPageHandler(w http.ResponseWriter, _ *http.Request, id string) {
+	var (
+		err            error
+		pendingInvites []string
+	)
+
+	if config.InvitesAllowed {
+		pendingInvites, err = db.GetInvitesList()
+		if err != nil {
+			log.Printf("Error fetching pending invites: %v\n", err)
+		}
+	}
+
 	_ = templates.ServeTemplate(
 		w,
 		templates.AdminHTML,
@@ -498,6 +515,8 @@ func AdminPageHandler(w http.ResponseWriter, _ *http.Request, id string) {
 				Config:     config.HTMLConfig,
 				Endpoints:  endpoints.HTMLPageEndpoints,
 			},
+			InvitesAllowed: config.InvitesAllowed,
+			PendingInvites: pendingInvites,
 		},
 	)
 }

backend/server/html/templates/admin.html

@@ -5,6 +5,31 @@
     <h1>Admin</h1>
     <hr>
 
+    {{ if .InvitesAllowed }}
+    <h3>Invites</h3>
+    {{ if .PendingInvites }}
+    <div>
+        <label for="pending-invites">Pending Invites:</label><br>
+        <select id="pending-invites" multiple size="10">
+            {{ range $val := .PendingInvites }}
+            <option value="{{$val}}">{{$val}}</option>
+            {{ end }}
+        </select>
+        <br>
+        <button id="revoke-invites" class="red-button">Revoke Selected Invites</button>
+    </div>
+    <hr class="half-hr">
+    {{ end }}
+
+    <div>
+        <label for="invite-emails">Insert a comma-separated list of emails to invite:</label><br>
+        <textarea id="invite-emails"></textarea>
+        <br>
+        <button id="send-invites" class="accent-btn">Send Invites</button>
+    </div>
+    <hr>
+    {{ end }}
+
     <h3>User Search</h3>
     <label for="user-id">User ID or Email:</label>
     <input type="text" id="user-id" placeholder="[email protected]"><br>