Validating user input in perl
When the flag is used on a validation filter other than FILTER_VALIDATE_BOOLEAN, as expected the filter will return NULL instead of FALSE upon failure.
In general, this validates e-mail addresses against the syntax in RFC 822, with the exceptions that comments and whitespace folding and dotless domain names are not supported. [email protected][PASS] news:comp.[FAIL] tel: 1-816-555-1212 [PASS] telnet://192.0.2./ [FAIL] urn:oasis:names:specification:docbook:dtd:xml:4.1.2 Notably missing is a way to validate text entry as printable,printable multiline,or printable and safe (tag free)FILTER_VALIDATE_TEXT, which validates no special charactersperhaps with FILTER_FLAG_ALLOW_NEWLINEand FILTER_FLAG_NOTAG to disallow tag starters Regarding "partial" addresses with no .FILTER_VALIDATE_URL does not work with URNs, examples of valid URIs according to RFC3986 and if they are accepted by FILTER_VALIDATE_URL: [PASS] ftp://example.org/rfc/rfc1808[PASS] gopher://spinaltap.example.edu/00/Weather/California/Los Angeles [PASS] mailto:[email protected][PASS] news:comp.[PASS] telnet://example.edu/ [PASS] ldap://[2001:db8::7]/c=GB? in the domain part, a comment in the source code (in ext/filter/logical_filters.c) justifies this rejection thus: * The regex below is based on a regex by Michael Rushton. I changed it to only consider routeable * addresses as valid.Michael's regex considers [email protected] a valid address * which conflicts with section 2.3.5 of RFC 5321 which states that: * * Only resolvable, fully-qualified domain names (FQDNs) are permitted * when domain names are used in SMTP.In other words, names that can * be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed * in Section 5) are permitted, as are CNAME RRs whose targets can be * resolved, in turn, to MX or address RRs.Local nicknames or * unqualified names MUST NOT be used.
For client side validation, the Java Script version can be used as is, for server side validation, rewriting the Java Script as C# is fairly straightforward.