shell-mail-address

#!/bin/sh -efu
### This file is covered by the GNU General Public License,
### which should be included with libshell as the file LICENSE.
### All copyright information are listed in the COPYING.

if [ -z "${__included_shell_mail_address-}" ]; then
__included_shell_mail_address=1

if [ -n "${shell_mail_address_strict-}" ]; then
	###
	### (http://en.wikipedia.org/wiki/Country_code_top-level_domain)
	###
	### A country code top-level domain (ccTLD) is an Internet top-level domain
	### generally used or reserved for a country or a dependent territory.
	###
	readonly regex_cctld_active='(a[cdefgilmnoqrstuwxz]|b[abdefghijmnorstwyz]|c[acdfghiklmnoruvxyz]|d[ejkmoz]|e[cegrstu]|f[ijkmor]|g[adefghilmnpqrstuwy]|h[kmnrtu]|i[delmnoqrst]|j[emop]|k[eghimnprwyz]|l[abcikrstuvy]|m[acdeghklmnopqrstuvwxyz]|n[acefgilopruz]|om|p[aefghklnrstwy]|qa|r[eosuw]|s[abcdeghiklmnrtuvyz]|t[cdfghjklmnortvwz]|u[agksyz]|v[aceginu]|w[fs]|ye|z[amw])'
	readonly regex_cctld_reserved='(um|bl|eh|mf)'
	readonly regex_cctld_allocated='(bv|gb|pm|sj|so|yt)'
	readonly regex_cctld_phaseout='(tp|yu)'
	readonly regex_cctld_deleted='(cs|dd|zr)'

	### (http://en.wikipedia.org/wiki/GTLD)
	###
	### A generic top-level domain (gTLD) is a top-level domain used by a
	### particular class of organization.
	###
	readonly regex_gtld='(aero|arpa|asia|biz|cat|com|coop|edu|gov|info|int|jobs|mil|mobi|museum|name|net|org|pro|tel|travel)'

	regex_tld="($regex_gtld|$regex_cctld_active|$regex_cctld_reserved|$regex_cctld_allocated|$regex_cctld_phaseout)"
else
	regex_tld='([a-zA-Z]{2,4}|museum|travel)'
fi

### 6. ADDRESS SPECIFICATION (http://tools.ietf.org/html/rfc822)
###
### addr-spec   =  local-part "@" domain        ; global address
### local-part  =  word *("." word)             ; uninterpreted
###                                             ; case-preserved
### domain      =  sub-domain *("." sub-domain)
### sub-domain  =  domain-ref / domain-literal
### domain-ref  =  atom                         ; symbolic reference
###
### 6.2.3. DOMAIN TERMS
### A domain-ref must be THE official name of a registry, network,
### or host.

### This regexp should be used ignoring case.
readonly regex_domain="([a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*)\.$regex_tld"

### Regexp can be used to check and parse email address. This regexp
### should be used ignoring case.
### Usage example:
### username="$(printf '%s' "$email" |sed -e "s/^$regex_email\$/\1/i")
###   domain="$(printf '%s' "$email" |sed -e "s/^$regex_email\$/\2/i")
###
readonly regex_email="([_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*)@($regex_domain)"

### Checks that given option value is a valid email address.
valid_email()
{
	local email="$1"
	printf '%s' "$email" |
		grep -E -iqs "^$regex_email\$" ||
		return 1
}

fi #__included_shell_mail_address