Restrict email address validation (#17688)

This didn't follow the RFC but it's a subset of that. I think we should narrow the allowed chars at first and discuss more possibility in future PRs.

4 files changed, 94 insertions, 7 deletions

diff --git a/models/user/email_address.go b/models/user/email_address.go
index 726af7b3b4..564d018dac 100644
--- a/models/user/email_address.go
+++ b/models/user/email_address.go
@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"net/mail"
+	"regexp"
 	"strings"
 
 	"code.gitea.io/gitea/models/db"
@@ -22,7 +23,22 @@ import (
 )
 
 // ErrEmailNotActivated e-mail address has not been activated error
-var ErrEmailNotActivated = errors.New("E-mail address has not been activated")
+var ErrEmailNotActivated = errors.New("e-mail address has not been activated")
+
+// ErrEmailCharIsNotSupported e-mail address contains unsupported character
+type ErrEmailCharIsNotSupported struct {
+	Email string
+}
+
+// IsErrEmailCharIsNotSupported checks if an error is an ErrEmailCharIsNotSupported
+func IsErrEmailCharIsNotSupported(err error) bool {
+	_, ok := err.(ErrEmailCharIsNotSupported)
+	return ok
+}
+
+func (err ErrEmailCharIsNotSupported) Error() string {
+	return fmt.Sprintf("e-mail address contains unsupported character [email: %s]", err.Email)
+}
 
 // ErrEmailInvalid represents an error where the email address does not comply with RFC 5322
 type ErrEmailInvalid struct {
@@ -106,12 +122,24 @@ func (email *EmailAddress) BeforeInsert() {
 	}
 }
 
+var emailRegexp = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]*@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
+
 // ValidateEmail check if email is a allowed address
 func ValidateEmail(email string) error {
 	if len(email) == 0 {
 		return nil
 	}
 
+	if !emailRegexp.MatchString(email) {
+		return ErrEmailCharIsNotSupported{email}
+	}
+
+	if !(email[0] >= 'a' && email[0] <= 'z') &&
+		!(email[0] >= 'A' && email[0] <= 'Z') &&
+		!(email[0] >= '0' && email[0] <= '9') {
+		return ErrEmailInvalid{email}
+	}
+
 	if _, err := mail.ParseAddress(email); err != nil {
 		return ErrEmailInvalid{email}
 	}
diff --git a/models/user/email_address_test.go b/models/user/email_address_test.go
index 4a539e150a..7eeb469b26 100644
--- a/models/user/email_address_test.go
+++ b/models/user/email_address_test.go
@@ -252,3 +252,58 @@ func TestListEmails(t *testing.T) {
 	assert.Len(t, emails, 5)
 	assert.Greater(t, count, int64(len(emails)))
 }
+
+func TestEmailAddressValidate(t *testing.T) {
+	kases := map[string]error{
+		"abc@gmail.com":                  nil,
+		"132@hotmail.com":                nil,
+		"1-3-2@test.org":                 nil,
+		"1.3.2@test.org":                 nil,
+		"a_123@test.org.cn":              nil,
+		`first.last@iana.org`:            nil,
+		`first!last@iana.org`:            nil,
+		`first#last@iana.org`:            nil,
+		`first$last@iana.org`:            nil,
+		`first%last@iana.org`:            nil,
+		`first&last@iana.org`:            nil,
+		`first'last@iana.org`:            nil,
+		`first*last@iana.org`:            nil,
+		`first+last@iana.org`:            nil,
+		`first/last@iana.org`:            nil,
+		`first=last@iana.org`:            nil,
+		`first?last@iana.org`:            nil,
+		`first^last@iana.org`:            nil,
+		"first`last@iana.org":            nil,
+		`first{last@iana.org`:            nil,
+		`first|last@iana.org`:            nil,
+		`first}last@iana.org`:            nil,
+		`first~last@iana.org`:            nil,
+		`first;last@iana.org`:            ErrEmailCharIsNotSupported{`first;last@iana.org`},
+		".233@qq.com":                    ErrEmailInvalid{".233@qq.com"},
+		"!233@qq.com":                    ErrEmailInvalid{"!233@qq.com"},
+		"#233@qq.com":                    ErrEmailInvalid{"#233@qq.com"},
+		"$233@qq.com":                    ErrEmailInvalid{"$233@qq.com"},
+		"%233@qq.com":                    ErrEmailInvalid{"%233@qq.com"},
+		"&233@qq.com":                    ErrEmailInvalid{"&233@qq.com"},
+		"'233@qq.com":                    ErrEmailInvalid{"'233@qq.com"},
+		"*233@qq.com":                    ErrEmailInvalid{"*233@qq.com"},
+		"+233@qq.com":                    ErrEmailInvalid{"+233@qq.com"},
+		"/233@qq.com":                    ErrEmailInvalid{"/233@qq.com"},
+		"=233@qq.com":                    ErrEmailInvalid{"=233@qq.com"},
+		"?233@qq.com":                    ErrEmailInvalid{"?233@qq.com"},
+		"^233@qq.com":                    ErrEmailInvalid{"^233@qq.com"},
+		"`233@qq.com":                    ErrEmailInvalid{"`233@qq.com"},
+		"{233@qq.com":                    ErrEmailInvalid{"{233@qq.com"},
+		"|233@qq.com":                    ErrEmailInvalid{"|233@qq.com"},
+		"}233@qq.com":                    ErrEmailInvalid{"}233@qq.com"},
+		"~233@qq.com":                    ErrEmailInvalid{"~233@qq.com"},
+		";233@qq.com":                    ErrEmailCharIsNotSupported{";233@qq.com"},
+		"Foo <foo@bar.com>":              ErrEmailCharIsNotSupported{"Foo <foo@bar.com>"},
+		string([]byte{0xE2, 0x84, 0xAA}): ErrEmailCharIsNotSupported{string([]byte{0xE2, 0x84, 0xAA})},
+	}
+	for kase, err := range kases {
+		t.Run(kase, func(t *testing.T) {
+			assert.EqualValues(t, err, ValidateEmail(kase))
+		})
+	}
+}
diff --git a/models/user/user.go b/models/user/user.go
index 3eabf4808c..a3094a13ce 100644
--- a/models/user/user.go
+++ b/models/user/user.go
@@ -644,6 +644,15 @@ func CreateUser(u *User, overwriteDefault ...*CreateUserOverwriteOptions) (err e
 		u.Visibility = overwriteDefault[0].Visibility
 	}
 
+	// validate data
+	if err := validateUser(u); err != nil {
+		return err
+	}
+
+	if err := ValidateEmail(u.Email); err != nil {
+		return err
+	}
+
 	ctx, committer, err := db.TxContext()
 	if err != nil {
 		return err
@@ -652,11 +661,6 @@ func CreateUser(u *User, overwriteDefault ...*CreateUserOverwriteOptions) (err e
 
 	sess := db.GetEngine(ctx)
 
-	// validate data
-	if err := validateUser(u); err != nil {
-		return err
-	}
-
 	isExist, err := isUserExist(sess, 0, u.Name)
 	if err != nil {
 		return err
diff --git a/models/user/user_test.go b/models/user/user_test.go
index a5f47172ee..335537aa13 100644
--- a/models/user/user_test.go
+++ b/models/user/user_test.go
@@ -232,7 +232,7 @@ func TestCreateUserInvalidEmail(t *testing.T) {
 
 	err := CreateUser(user)
 	assert.Error(t, err)
-	assert.True(t, IsErrEmailInvalid(err))
+	assert.True(t, IsErrEmailCharIsNotSupported(err))
 }
 
 func TestCreateUserEmailAlreadyUsed(t *testing.T) {