Input validation is performed to ensure only properly formed data is entering the workflow in an information system, preventing malformed data from persisting in the database and triggering malfunction of various downstream components.
Input validation should happen as early as possible in the data flow, preferably as soon as the data is received from the external party.
In summary, input validation should: Example validating the parameter “zip” using a regular expression.
When you submit a form to a CGI program that resides on the server, it is usually programmed to do its own check for errors.
If it's well structured data, like dates, social security numbers, zip codes, e-mail addresses, etc.
then the developer should be able to define a very strong validation pattern, usually based on regular expressions, for validating such input.
Recent changes to the landscape mean that the number of false-negatives will increase, particularly due to: To ensure an address is deliverable, the only way to check this is to send the user an email and have the user take action to confirm receipt.
Beyond confirming that the email address is valid and deliverable, this also provides a positive acknowledgement that the user has access to the mailbox and is likely to be authorized to use it.
Input validation can be implemented using any programming technique that allows effective enforcement of syntactic and semantic correctness, for example: , where the ' character is fully legitimate.