Make e-mail sanity check more precise (#20991)

For security reasons, all e-mail addresses starting with
non-alphanumeric characters were rejected. This is too broad and rejects
perfectly valid e-mail addresses. Only leading hyphens should be
rejected -- in all other cases e-mail address specification should
follow RFC 5322.

Co-authored-by: Andreas Fischer <[email protected]>
Co-authored-by: 6543 <[email protected]>
Co-authored-by: zeripath <[email protected]>
Co-authored-by: techknowlogick <[email protected]>

Author: 5 people

models/user/email_address.go

@@ -41,6 +41,7 @@ func (err ErrEmailCharIsNotSupported) Error() string {
 }
 
 // ErrEmailInvalid represents an error where the email address does not comply with RFC 5322
+// or has a leading '-' character
 type ErrEmailInvalid struct {
 	Email string
 }
@@ -134,9 +135,7 @@ func ValidateEmail(email string) error {
 		return ErrEmailCharIsNotSupported{email}
 	}
 
-	if !(email[0] >= 'a' && email[0] <= 'z') &&
-		!(email[0] >= 'A' && email[0] <= 'Z') &&
-		!(email[0] >= '0' && email[0] <= '9') {
+	if email[0] == '-' {
 		return ErrEmailInvalid{email}
 	}
 

models/user/email_address_test.go

@@ -281,23 +281,25 @@ func TestEmailAddressValidate(t *testing.T) {
 		`[email protected]`:            nil,
 		`first;[email protected]`:            user_model.ErrEmailCharIsNotSupported{`first;[email protected]`},
 		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
-		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
-		"#[email protected]":                    user_model.ErrEmailInvalid{"#[email protected]"},
-		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
-		"%[email protected]":                    user_model.ErrEmailInvalid{"%[email protected]"},
-		"&[email protected]":                    user_model.ErrEmailInvalid{"&[email protected]"},
-		"'[email protected]":                    user_model.ErrEmailInvalid{"'[email protected]"},
-		"*[email protected]":                    user_model.ErrEmailInvalid{"*[email protected]"},
-		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
-		"/[email protected]":                    user_model.ErrEmailInvalid{"/[email protected]"},
-		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
-		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
-		"^[email protected]":                    user_model.ErrEmailInvalid{"^[email protected]"},
-		"`[email protected]":                    user_model.ErrEmailInvalid{"`[email protected]"},
-		"{[email protected]":                    user_model.ErrEmailInvalid{"{[email protected]"},
-		"|[email protected]":                    user_model.ErrEmailInvalid{"|[email protected]"},
-		"}[email protected]":                    user_model.ErrEmailInvalid{"}[email protected]"},
-		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
+		"[email protected]":                    nil,
+		"#[email protected]":                    nil,
+		"[email protected]":                    nil,
+		"%[email protected]":                    nil,
+		"&[email protected]":                    nil,
+		"'[email protected]":                    nil,
+		"*[email protected]":                    nil,
+		"[email protected]":                    nil,
+		"[email protected]":                    user_model.ErrEmailInvalid{"[email protected]"},
+		"/[email protected]":                    nil,
+		"[email protected]":                    nil,
+		"[email protected]":                    nil,
+		"^[email protected]":                    nil,
+		"[email protected]":                    nil,
+		"`[email protected]":                    nil,
+		"{[email protected]":                    nil,
+		"|[email protected]":                    nil,
+		"}[email protected]":                    nil,
+		"[email protected]":                    nil,
 		";[email protected]":                    user_model.ErrEmailCharIsNotSupported{";[email protected]"},
 		"Foo <[email protected]>":              user_model.ErrEmailCharIsNotSupported{"Foo <[email protected]>"},
 		string([]byte{0xE2, 0x84, 0xAA}): user_model.ErrEmailCharIsNotSupported{string([]byte{0xE2, 0x84, 0xAA})},