Class: DomainNameValidator

Inherits:
Object
  • Object
show all
Defined in:
lib/domain_name_validator/validator.rb,
lib/domain_name_validator.rb,
lib/domain_name_validator/version.rb

Overview

The purpose of this class is to provide a simple capability for validating domain names represented in ASCII, a feature that seems to be missing or obscured in other more wide-ranging domain-related gems.

Constant Summary collapse

VERSION = 
"0.5"
MAX_DOMAIN_LENGTH = 
253
MAX_LABEL_LENGTH = 
63
MAX_LEVELS = 
127
MAX_TLD_LENGTH =

Except for “aero”, “arpa”, “info” and “museum”

3
MIN_LEVELS = 
2
MIN_TLD_LENGTH = 
2
ERRS = 
{
:bogus_tld =>
   'Malformed TLD: Could not possibly match any valid TLD',
:illegal_chars =>
   'Domain label contains an illegal character',
:illegal_start =>
   'No domain name may start with a period',
:label_dash_begin =>
   'No domain label may begin with a dash',
:label_dash_end =>
   'No domain label may end with a dash',
:max_domain_size =>
   'Maximum domain length of 253 exceeded',
:max_label_size =>
   'Maximum domain label length of 63 exceeded',
:max_level_size =>
   'Maximum domain level limit of 127 exceeded',
:min_level_size =>
   'Minimum domain level limit of 2 not achieved',
:top_numerical =>
   'The top-level domain (TLD) cannot be numerical',
:zero_size =>
   'Zero-length domain name'
}

Instance Method Summary collapse

Instance Method Details

#validate(dn, errs = []) ⇒ Object

Validates the proper formatting of a normalized domain name, i.e. - a domain that is represented in ASCII. Thus, international domain names are supported and validated, if they have undergone the required IDN conversion to ASCII. The validation rules are:

  1. The maximum length of a domain name is 253 characters.

  2. A domain name is divided into “labels” separated by periods. The maximum number of labels (including the top-level domain as a label) is 127.

  3. The maximum length of any label within a domain name is 63 characters.

  4. No label, including top-level domains, can begin or end with a dash.

  5. Top-level names cannot be all numeric.

  6. A domain name cannot begin with a period.



52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
 
# File 'lib/domain_name_validator/validator.rb', line 52

def validate(dn, errs = [])
  if dn.nil?
    errs << ERRS[:zero_size]
  else
    dn = dn.strip
    errs << ERRS[:zero_size] if dn.size == 0
  end

  if errs.size == 0
    errs << ERRS[:max_domain_size] if dn.size > MAX_DOMAIN_LENGTH
    parts = dn.downcase.split('.')
    errs << ERRS[:max_level_size] if parts.size > MAX_LEVELS
    errs << ERRS[:min_level_size] if parts.size < MIN_LEVELS
    parts.each do |p|
      errs << ERRS[:max_label_size] if p.size > MAX_LABEL_LENGTH
      errs << ERRS[:label_dash_begin] if p[0] == '-'
      errs << ERRS[:label_dash_end] if p[-1] == '-'
      errs << ERRS[:illegal_chars] unless p.match(/^[a-z0-9\-\_]+$/)
    end
    errs << ERRS[:top_numerical] if parts.last.match(/^[0-9]+$/)
    if parts.last.size < MIN_TLD_LENGTH || parts.last.size > MAX_TLD_LENGTH
      unless parts.last == 'arpa' ||
             parts.last == 'aero' ||
             parts.last == 'asia' ||
             parts.last == 'coop' ||
             parts.last == 'info' ||
             parts.last == 'jobs' ||
             parts.last == 'mobi' ||
             parts.last == 'museum' ||
             parts.last == 'name' ||
             parts.last == 'post' ||
             parts.last == 'travel' ||
             parts.last.match(/^xn--/)
        errs << ERRS[:bogus_tld]   
      end
    end
    errs << ERRS[:illegal_start] if parts.first[0] == '.'
  end

  errs.size == 0   # TRUE if valid, FALSE otherwise
end