FILTER_VALIDATE_URL的FILTER_FLAG_SCHEME_REQUIRED和FILTER_FLAG_HOST_REQUIRED标志有什么用？

Question

我们可以使用filter_vars()with FILTER_VALIDATE_URL和flags：

FILTER_FLAG_SCHEME_REQUIRED
FILTER_FLAG_HOST_REQUIRED
FILTER_FLAG_PATH_REQUIRED
FILTER_FLAG_QUERY_REQUIRED

FILTER_VALIDATE_URL根据RFC 2396将值验证为URL，并在内部使用parse_url()并需要方案（协议）和主机部分。

如果我还想检查路径和查询零件，则可以这样使用filter_vars：

filter_var($url, FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED | FILTER_FLAG_QUERY_REQUIRED);

但是FILTER_FLAG_SCHEME_REQUIREDand FILTER_FLAG_HOST_REQUIRED标志的用途是什么？无论我们是否指定这些标志，似乎无论如何都将检查主机部件。

例如，如下过滤有效的相对URL：

filter_var('test1/2.html', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED);

返回false。

Answer 1

PHP 7.3.0

FILTER_FLAG_SCHEME_REQUIRED而FILTER_FLAG_HOST_REQUIRED现在已被弃用的PHP 7.3.0，因为他们使用FILTER_VALIDATE_URL反正。

你是对的。这两个标志默认情况下处于打开状态，尽管有官方文档中所述（请参见下文），也无法禁用它们。正如您在问题中所写，它们是无用的。我认为这是一个错误。有一个bug报告与此有关。

从PHP文档：

当心有效的URL可能未指定HTTP协议http：//，因此可能需要进一步的验证才能确定URL使用预期的协议，例如ssh：//或mailto:。

从RFC2396开始：

  URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
  absoluteURI   = scheme ":" ( hier_part | opaque_part )
  relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]

  hier_part     = ( net_path | abs_path ) [ "?" query ]
  opaque_part   = uric_no_slash *uric

  uric_no_slash = unreserved | escaped | ";" | "?" | ":" | "@" |
                  "&" | "=" | "+" | "$" | ","

  net_path      = "//" authority [ abs_path ]
  abs_path      = "/"  path_segments
  rel_path      = rel_segment [ abs_path ]

  rel_segment   = 1*( unreserved | escaped |
                      ";" | "@" | "&" | "=" | "+" | "$" | "," )

  scheme        = alpha *( alpha | digit | "+" | "-" | "." )

  authority     = server | reg_name

  reg_name      = 1*( unreserved | escaped | "$" | "," |
                      ";" | ":" | "@" | "&" | "=" | "+" )

  server        = [ [ userinfo "@" ] hostport ]
  userinfo      = *( unreserved | escaped |
                     ";" | ":" | "&" | "=" | "+" | "$" | "," )

  hostport      = host [ ":" port ]
  host          = hostname | IPv4address
  hostname      = *( domainlabel "." ) toplabel [ "." ]
  domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
  toplabel      = alpha | alpha *( alphanum | "-" ) alphanum
  IPv4address   = 1*digit "." 1*digit "." 1*digit "." 1*digit
  port          = *digit

  path          = [ abs_path | opaque_part ]
  path_segments = segment *( "/" segment )
  segment       = *pchar *( ";" param )
  param         = *pchar
  pchar         = unreserved | escaped |
                  ":" | "@" | "&" | "=" | "+" | "$" | ","

  query         = *uric

  fragment      = *uric

  uric          = reserved | unreserved | escaped
  reserved      = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
                  "$" | ","
  unreserved    = alphanum | mark
  mark          = "-" | "_" | "." | "!" | "~" | "*" | "'" |
                  "(" | ")"

  escaped       = "%" hex hex
  hex           = digit | "A" | "B" | "C" | "D" | "E" | "F" |
                          "a" | "b" | "c" | "d" | "e" | "f"

  alphanum      = alpha | digit
  alpha         = lowalpha | upalpha

  lowalpha = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" |
             "j" | "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" |
             "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z"
  upalpha  = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" |
             "J" | "K" | "L" | "M" | "N" | "O" | "P" | "Q" | "R" |
             "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z"
  digit    = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |
             "8" | "9"

如您所见，有效的URL可能没有方案部分或主机名部分（如果是相对的）。也许，FILTER_FLAG_SCHEME_REQUIRED并FILTER_FLAG_HOST_REQUIRED应有助于设计，以检查它们的存在。但这是不可能的。