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... The contents of the Payload field vary depending on the Opcode,
but most often it contains a null-terminated URL string.
...
... than most of the others. First is the requester's IPv4 address,
followed by a URL. The Requester Host Address is not that of the
...
... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ Null-Terminated URL /
/ /
| |
...
... port. The
payload is simply the null-terminated URL.
NOTE: one problem with this approach is that while a system's echo ...
... QUERY message. Unless otherwise noted, the payload must be
the null-terminated URL string. Both the URL string and the Request
Number field ...
... payload must be
the null-terminated URL string. Both the URL string and the Request
Number field must be exactly the same as from the ICP ...
... An ICP_OP_HIT response indicates that the requested URL exists in
this cache and that the requester is allowed to retrieve it.
...
... ICP_OP_MISS
An ICP_OP_MISS response indicates that the requested URL does not
exist in this cache. The querying cache ...
... ERR response indicates some kind of error in parsing or
handling the query message (e.g. invalid URL).
ICP ...
... misses. ICP_OP_MISS_NOFETCH essentially means "I am up and
running, but please don't fetch this URL from me now."
Note, ICP ...
... ICP_OP_MISS. The ICP_OP_MISS reply is an invitation to fetch the
URL from the replying cache (if their relationship allows it), but
ICP ...
... cache (if their relationship allows it), but
ICP_OP_MISS_NOFETCH is a request to NOT fetch the URL from the
replying cache.
...
... proxies may implement complex access controls. This reply must be
be interpreted to mean "you are not allowed to request this
particular URL from me at this particular time."
Caches ...
... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ Null-Terminated URL /
/ /
| |
...
... 32-bit
boundary as shown in the diagram above. It begins immediately
following the NULL byte of the URL string.
UNRECOGNIZED OPCODES
...
... Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform Resource Locators (URL)", RFC 1738(-> 4266prop | 4248prop), CERN, Xerox PARC, University of Minnesota, December 1994. ...