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package validate |
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import ( |
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"errors" |
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"net/url" |
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) |
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var ( |
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ErrUnexpectedProtocol = errors.New("unexpected protocol") |
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) |
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// URL is used to validate that value is a valid absolute URL string, which means that a protocol (or scheme) |
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// is required. By default (if no protocols are passed), the function checks only for |
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// the http:// and https:// protocols. Use the protocols argument to configure the list of expected protocols. |
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// |
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// If value is not a valid URL the function will return one of the errors: |
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// • parsing error from url.Parse method if value cannot be parsed as an URL; |
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// • ErrUnexpectedProtocol if protocol is not matching one of the listed protocols; |
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// • ErrInvalid if value is not matching the regular expression. |
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func URL(value string, protocols ...string) error { |
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return validateURL(value, false, protocols...) |
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} |
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// RelativeURL is used to validate that value is a valid absolute or relative URL string. The protocol is considered |
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// optional when validating the syntax of the given URL. This means that both http:// and https:// are valid |
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// but also relative URLs that contain no protocol (e.g. //example.com). By default, the function checks |
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// only for the http:// and https:// protocols. Use the protocols argument to configure |
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// the list of expected protocols. |
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// |
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// If value is not a valid URL the function will return one of the errors: |
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// • parsing error from url.Parse method if value cannot be parsed as an URL; |
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// • ErrUnexpectedProtocol if protocol is not matching one of the listed protocols or it is not a relative URL; |
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// • ErrInvalid if value is not matching the regular expression. |
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func RelativeURL(value string, protocols ...string) error { |
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return validateURL(value, true, protocols...) |
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} |
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func validateURL(value string, isRelative bool, protocols ...string) error { |
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if len(protocols) == 0 { |
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protocols = []string{"http", "https"} |
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} |
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u, err := url.Parse(value) |
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if err != nil { |
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return err |
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} |
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err = validateProtocol(u, isRelative, protocols) |
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if err != nil { |
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return err |
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} |
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if !urlRegex.MatchString(value) { |
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return ErrInvalid |
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} |
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return nil |
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} |
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func validateProtocol(u *url.URL, isRelative bool, protocols []string) error { |
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if isRelative && u.Scheme == "" { |
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return nil |
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} |
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for _, protocol := range protocols { |
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if protocol == u.Scheme { |
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return nil |
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} |
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} |
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return ErrUnexpectedProtocol |
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} |
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