Email validation is passing invalid domain names with consecutive dots

[kei2100]

• I have looked at the documentation here first?
• I have looked at the examples provided that may showcase my question here?

Package version eg. v9, v10:

v10

Issue, Question or Enhancement:

Email validation seems to pass invalid domain names such as

• test@yahoo..co.jp
• test@yahoo.co..jp
• test@yahoo.co...jp

Code sample, to showcase or reproduce:

https://play.golang.org/p/V3yIIe37-1G

[4k1k0]

It seems that this behavior only works with emails which contains two or more top domains.

✔️ test@yahoo..co.jp
✔️ test@yahoo.co..jp
✔️ test@yahoo.co...jp
✔️ test@yahoo.co...jp.mx
❎ test@..com
❎ test@ya..com
❎ test@ya..com..net
✔️ test@ya..com..net.mx
❎ test@ya..com..net..mx

[4k1k0]

I replace the email regex using this one from govalidator

emailRegexString = "^(((([a-zA-Z]|\\d|[!#\\$%&'\\*\\+\\-\\/=\\?\\^_`{\\|}~]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])+(\\.([a-zA-Z]|\\d|[!#\\$%&'\\*\\+\\-\\/=\\?\\^_`{\\|}~]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])+)*)|((\\x22)((((\\x20|\\x09)*(\\x0d\\x0a))?(\\x20|\\x09)+)?(([\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x7f]|\\x21|[\\x23-\\x5b]|[\\x5d-\\x7e]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(\\([\\x01-\\x09\\x0b\\x0c\\x0d-\\x7f]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}]))))*(((\\x20|\\x09)*(\\x0d\\x0a))?(\\x20|\\x09)+)?(\\x22)))@((([a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(([a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])([a-zA-Z]|\\d|-|\\.|_|~|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])*([a-zA-Z]|\\d|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])))\\.)+(([a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])|(([a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])([a-zA-Z]|\\d|-|_|~|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])*([a-zA-Z]|[\\x{00A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}])))\\.?$"

And I added the tests cases for this issue

	s = "test@yahoo..co.jp"
	errs = validate.Var(s, "email")
	NotEqual(t, errs, nil)
	AssertError(t, errs, "", "", "", "", "email")

	s = "test@yahoo.co...jp.mx"
	errs = validate.Var(s, "email")
	NotEqual(t, errs, nil)
	AssertError(t, errs, "", "", "", "", "email")

This regex validates the multiple dots on the domain, but it doesn't pass the use case for email with underscores

        s = "mail@domain_with_underscores.org"
	errs = validate.Var(s, "email")
	NotEqual(t, errs, nil)
	AssertError(t, errs, "", "", "", "", "email")

I will try to include the underscores in this regular expression.

[deankarn]

@kei2100 @4k1k0 yes this has been a long standing issue I just haven't had time to address yet.

I was going to change to use the regex generated here as the base. but even it doesn't;t handle all use cases so need to flesh some extra logic out with it also.