email block checking for signups

internal/db/db.go

@@ -138,8 +138,11 @@ type DB interface {
 	// Returns an error if the username is already taken, or something went wrong in the db.
 	IsUsernameAvailable(username string) error
 
-	// IsEmailAvailable checks whether a given email address for a user is available on our domain.
-	// Returns an error if the email is already associated with an account, or something went wrong in the db.
+	// IsEmailAvailable checks whether a given email address for a new account is available to be used on our domain.
+	// Return an error if:
+	// A) the email is already associated with an account
+	// B) we block signups from this email domain
+	// C) something went wrong in the db
 	IsEmailAvailable(email string) error
 
 	/*

internal/db/model/emaildomainblock.go

@@ -20,13 +20,11 @@ package model
 
 import "time"
 
-// SignUpDomainBlock represents a domain that the server should automatically reject sign-up requests from.
-type SignUpDomainBlock struct {
+// EmailDomainBlock represents a domain that the server should automatically reject sign-up requests from.
+type EmailDomainBlock struct {
 	// ID of this block in the database
 	ID string `pg:"type:uuid,default:gen_random_uuid(),pk,notnull,unique"`
-	// Domain to block. If ANY PART of the candidate domain contains this string, it will be blocked.
-	// For example: 'example.org' also blocks 'gts.example.org'. '.com' blocks *any* '.com' domains.
-	// TODO: implement wildcards here
+	// Email domain to block. Eg. 'gmail.com' or 'hotmail.com'
 	Domain string `pg:",notnull"`
 	// When was this block created
 	CreatedAt time.Time `pg:"type:timestamp,notnull,default:now()"`

internal/db/pg.go

@@ -22,6 +22,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net/mail"
 	"regexp"
 	"strings"
 	"time"
@@ -378,19 +379,35 @@ func (ps *postgresService) IsUsernameAvailable(username string) error {
 	if err := ps.conn.Model(&model.Account{}).Where("username = ?").Where("domain = ?", nil).Select(); err == nil {
 		return fmt.Errorf("username %s already in use", username)
 	} else if err != pg.ErrNoRows {
-		return err
+		return fmt.Errorf("db error: %s", err)
 	}
 	return nil
 }
 
 func (ps *postgresService) IsEmailAvailable(email string) error {
-	// if no error we fail because it means we found something
-	// if error but it's not db.ErrorNoEntries then we fail
-	// if err is ErrNoEntries we're good, we found nothing so continue
+	// parse the domain from the email
+	m, err := mail.ParseAddress(email)
+	if err != nil {
+		return fmt.Errorf("error parsing email address %s: %s", email, err)
+	}
+	domain := strings.Split(m.Address, "@")[1] // domain will always be the second part after @
+
+	// check if the email domain is blocked
+	if err := ps.conn.Model(&model.EmailDomainBlock{}).Where("domain = ?", domain).Select(); err == nil {
+		// fail because we found something
+		return fmt.Errorf("email domain %s is blocked", domain)
+	} else if err != pg.ErrNoRows {
+		// fail because we got an unexpected error
+		return fmt.Errorf("db error: %s", err)
+	}
+	
+	// check if this email is associated with an account already
 	if err := ps.conn.Model(&model.Account{}).Where("email = ?", email).WhereOr("unconfirmed_email = ?", email).Select(); err == nil {
+		// fail because we found something
 		return fmt.Errorf("email %s already in use", email)
 	} else if err != pg.ErrNoRows {
-		return err
+		// fail because we got an unexpected error
+		return fmt.Errorf("db error: %s", err)
 	}
 	return nil
 }