rfc1738.txt

<VC++网络游戏建摸与实现>源代码

; Miscellaneous definitions

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"
hialpha        = "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"



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alpha          = lowalpha | hialpha
digit          = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |
                 "8" | "9"
safe           = "$" | "-" | "_" | "." | "+"
extra          = "!" | "*" | "'" | "(" | ")" | ","
national       = "{" | "}" | "|" | "\" | "^" | "~" | "[" | "]" | "`"
punctuation    = "<" | ">" | "#" | "%" | <">


reserved       = ";" | "/" | "?" | ":" | "@" | "&" | "="
hex            = digit | "A" | "B" | "C" | "D" | "E" | "F" |
                 "a" | "b" | "c" | "d" | "e" | "f"
escape         = "%" hex hex

unreserved     = alpha | digit | safe | extra
uchar          = unreserved | escape
xchar          = unreserved | reserved | escape
digits         = 1*digit

6. Security Considerations

   The URL scheme does not in itself pose a security threat. Users
   should beware that there is no general guarantee that a URL which at
   one time points to a given object continues to do so, and does not
   even at some later time point to a different object due to the
   movement of objects on servers.

   A URL-related security threat is that it is sometimes possible to
   construct a URL such that an attempt to perform a harmless idempotent
   operation such as the retrieval of the object will in fact cause a
   possibly damaging remote operation to occur.  The unsafe URL is
   typically constructed by specifying a port number other than that
   reserved for the network protocol in question.  The client
   unwittingly contacts a server which is in fact running a different
   protocol.  The content of the URL contains instructions which when
   interpreted according to this other protocol cause an unexpected
   operation. An example has been the use of gopher URLs to cause a rude
   message to be sent via a SMTP server.  Caution should be used when
   using any URL which specifies a port number other than the default
   for the protocol, especially when it is a number within the reserved
   space.

   Care should be taken when URLs contain embedded encoded delimiters
   for a given protocol (for example, CR and LF characters for telnet
   protocols) that these are not unencoded before transmission.  This
   would violate the protocol but could be used to simulate an extra
   operation or parameter, again causing an unexpected and possible
   harmful remote operation to be performed.



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   The use of URLs containing passwords that should be secret is clearly
   unwise.

7. Acknowledgements

   This paper builds on the basic WWW design (RFC 1630) and much
   discussion of these issues by many people on the network. The
   discussion was particularly stimulated by articles by Clifford Lynch,
   Brewster Kahle [10] and Wengyik Yeong [18]. Contributions from John
   Curran, Clifford Neuman, Ed Vielmetti and later the IETF URL BOF and
   URI working group were incorporated.

   Most recently, careful readings and comments by Dan Connolly, Ned
   Freed, Roy Fielding, Guido van Rossum, Michael Dolan, Bert Bos, John
   Kunze, Olle Jarnefors, Peter Svanberg and many others have helped
   refine this RFC.



































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APPENDIX: Recommendations for URLs in Context

   URIs, including URLs, are intended to be transmitted through
   protocols which provide a context for their interpretation.

   In some cases, it will be necessary to distinguish URLs from other
   possible data structures in a syntactic structure. In this case, is
   recommended that URLs be preceeded with a prefix consisting of the
   characters "URL:". For example, this prefix may be used to
   distinguish URLs from other kinds of URIs.

   In addition, there are many occasions when URLs are included in other
   kinds of text; examples include electronic mail, USENET news
   messages, or printed on paper. In such cases, it is convenient to
   have a separate syntactic wrapper that delimits the URL and separates
   it from the rest of the text, and in particular from punctuation
   marks that might be mistaken for part of the URL. For this purpose,
   is recommended that angle brackets ("<" and ">"), along with the
   prefix "URL:", be used to delimit the boundaries of the URL.  This
   wrapper does not form part of the URL and should not be used in
   contexts in which delimiters are already specified.

   In the case where a fragment/anchor identifier is associated with a
   URL (following a "#"), the identifier would be placed within the
   brackets as well.

   In some cases, extra whitespace (spaces, linebreaks, tabs, etc.) may
   need to be added to break long URLs across lines.  The whitespace
   should be ignored when extracting the URL.

   No whitespace should be introduced after a hyphen ("-") character.
   Because some typesetters and printers may (erroneously) introduce a
   hyphen at the end of line when breaking a line, the interpreter of a
   URL containing a line break immediately after a hyphen should ignore
   all unencoded whitespace around the line break, and should be aware
   that the hyphen may or may not actually be part of the URL.

   Examples:

      Yes, Jim, I found it under <URL:ftp://info.cern.ch/pub/www/doc;
      type=d> but you can probably pick it up from <URL:ftp://ds.in
      ternic.net/rfc>.  Note the warning in <URL:http://ds.internic.
      net/instructions/overview.html#WARNING>.








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References

   [1] Anklesaria, F., McCahill, M., Lindner, P., Johnson, D.,
       Torrey, D., and B. Alberti, "The Internet Gopher Protocol
       (a distributed document search and retrieval protocol)",
       RFC 1436, University of Minnesota, March 1993.
       <URL:ftp://ds.internic.net/rfc/rfc1436.txt;type=a>

   [2] Anklesaria, F., Lindner, P., McCahill, M., Torrey, D.,
       Johnson, D., and B. Alberti, "Gopher+: Upward compatible
       enhancements to the Internet Gopher protocol",
       University of Minnesota, July 1993.
       <URL:ftp://boombox.micro.umn.edu/pub/gopher/gopher_protocol
       /Gopher+/Gopher+.txt>

   [3] Berners-Lee, T., "Universal Resource Identifiers in WWW: A
       Unifying Syntax for the Expression of Names and Addresses of
       Objects on the Network as used in the World-Wide Web", RFC
       1630, CERN, June 1994.
       <URL:ftp://ds.internic.net/rfc/rfc1630.txt>

   [4] Berners-Lee, T., "Hypertext Transfer Protocol (HTTP)",
       CERN, November 1993.
       <URL:ftp://info.cern.ch/pub/www/doc/http-spec.txt.Z>

   [5] Braden, R., Editor, "Requirements for Internet Hosts --
       Application and Support", STD 3, RFC 1123, IETF, October 1989.
       <URL:ftp://ds.internic.net/rfc/rfc1123.txt>

   [6] Crocker, D. "Standard for the Format of ARPA Internet Text
       Messages", STD 11, RFC 822, UDEL, April 1982.
       <URL:ftp://ds.internic.net/rfc/rfc822.txt>

   [7] Davis, F., Kahle, B., Morris, H., Salem, J., Shen, T., Wang, R.,
       Sui, J., and M. Grinbaum, "WAIS Interface Protocol Prototype
       Functional Specification", (v1.5), Thinking Machines
       Corporation, April 1990.
       <URL:ftp://quake.think.com/pub/wais/doc/protspec.txt>

   [8] Horton, M. and R. Adams, "Standard For Interchange of USENET
       Messages", RFC 1036, AT&T Bell Laboratories, Center for Seismic
       Studies, December 1987.
       <URL:ftp://ds.internic.net/rfc/rfc1036.txt>

   [9] Huitema, C., "Naming: Strategies and Techniques", Computer
       Networks and ISDN Systems 23 (1991) 107-110.





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  [10] Kahle, B., "Document Identifiers, or International Standard
       Book Numbers for the Electronic Age", 1991.
       <URL:ftp://quake.think.com/pub/wais/doc/doc-ids.txt>

  [11] Kantor, B. and P. Lapsley, "Network News Transfer Protocol:
       A Proposed Standard for the Stream-Based Transmission of News",
       RFC 977, UC San Diego & UC Berkeley, February 1986.
       <URL:ftp://ds.internic.net/rfc/rfc977.txt>

  [12] Kunze, J., "Functional Requirements for Internet Resource
       Locators", Work in Progress, December 1994.
       <URL:ftp://ds.internic.net/internet-drafts
       /draft-ietf-uri-irl-fun-req-02.txt>

  [13] Mockapetris, P., "Domain Names - Concepts and Facilities",
       STD 13, RFC 1034, USC/Information Sciences Institute,
       November 1987.
       <URL:ftp://ds.internic.net/rfc/rfc1034.txt>

  [14] Neuman, B., and S. Augart, "The Prospero Protocol",
       USC/Information Sciences Institute, June 1993.
       <URL:ftp://prospero.isi.edu/pub/prospero/doc
       /prospero-protocol.PS.Z>

  [15] Postel, J. and J. Reynolds, "File Transfer Protocol (FTP)",
       STD 9, RFC 959, USC/Information Sciences Institute,
       October 1985.
       <URL:ftp://ds.internic.net/rfc/rfc959.txt>

  [16] Sollins, K. and L. Masinter, "Functional Requirements for
       Uniform Resource Names", RFC 1737, MIT/LCS, Xerox Corporation,
       December 1994.
       <URL:ftp://ds.internic.net/rfc/rfc1737.txt>

  [17] St. Pierre, M, Fullton, J., Gamiel, K., Goldman, J., Kahle, B.,
       Kunze, J., Morris, H., and F. Schiettecatte, "WAIS over
       Z39.50-1988", RFC 1625, WAIS, Inc., CNIDR, Thinking Machines
       Corp., UC Berkeley, FS Consulting, June 1994.
       <URL:ftp://ds.internic.net/rfc/rfc1625.txt>

  [18] Yeong, W. "Towards Networked Information Retrieval", Technical
       report 91-06-25-01, Performance Systems International, Inc.
       <URL:ftp://uu.psi.com/wp/nir.txt>, June 1991.

  [19] Yeong, W., "Representing Public Archives in the Directory",
       Work in Progress, November 1991.





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  [20] "Coded Character Set -- 7-bit American Standard Code for
       Information Interchange", ANSI X3.4-1986.

Editors' Addresses

Tim Berners-Lee
World-Wide Web project
CERN,
1211 Geneva 23,
Switzerland

Phone: [phone]
Fax: [phone]
EMail: [e-mail]


Larry Masinter
Xerox PARC
3333 Coyote Hill Road
Palo Alto, CA 94034

Phone: [phone]
Fax: [phone]
EMail: [e-mail]


Mark McCahill
Computer and Information Services,
University of Minnesota
Room 152 Shepherd Labs
100 Union Street SE
Minneapolis, MN 55455

Phone: [phone]
EMail: [e-mail]
















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