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# Copyright (C) 2006 Canonical Ltd
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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"""Smart-server protocol, client and server.
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This code is fairly complex, so it has been split up into a package of modules,
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rather than being a single large module. Refer to the individual module
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docstrings for details.
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Server-side request handlers are registered in the `bzrlib.smart.request`
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The domain logic is in `bzrlib.remote`: `RemoteBzrDir`, `RemoteBranch`,
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There is also an plain file-level transport that calls remote methods to
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manipulate files on the server in `bzrlib.transport.remote`.
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The protocol is described in doc/developers/network-protocol.txt.
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# TODO: _translate_error should be on the client, not the transport because
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# error coding is wire protocol specific.
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# TODO: A plain integer from query_version is too simple; should give some
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# TODO: Server should probably catch exceptions within itself and send them
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# back across the network. (But shouldn't catch KeyboardInterrupt etc)
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# Also needs to somehow report protocol errors like bad requests. Need to
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# consider how we'll handle error reporting, e.g. if we get halfway through a
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# bulk transfer and then something goes wrong.
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# TODO: Make each request and response self-validatable, e.g. with checksums.
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# TODO: get/put objects could be changed to gradually read back the data as it
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# comes across the network
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# TODO: What should the server do if it hits an error and has to terminate?
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# TODO: is it useful to allow multiple chunks in the bulk data?
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# TODO: If we get an exception during transmission of bulk data we can't just
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# emit the exception because it won't be seen.
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# John proposes: I think it would be worthwhile to have a header on each
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# chunk, that indicates it is another chunk. Then you can send an 'error'
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# chunk as long as you finish the previous chunk.
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# TODO: Clone method on Transport; should work up towards parent directory;
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# unclear how this should be stored or communicated to the server... maybe
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# just pass it on all relevant requests?
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# TODO: Better name than clone() for changing between directories. How about
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# open_dir or change_dir or chdir?
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# TODO: Is it really good to have the notion of current directory within the
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# connection? Perhaps all Transports should factor out a common connection
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# from the thing that has the directory context?
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# TODO: The server that manages a connection should be quite small and retain
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# minimum state because each of the requests are supposed to be stateless.
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# Then we can write another implementation that maps to http.
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# TODO: What to do when a client connection is garbage collected? Maybe just
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# abruptly drop the connection?
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# TODO: Server in some cases will need to restrict access to files outside of
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# a particular root directory. LocalTransport doesn't do anything to stop you
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# ascending above the base directory, so we need to prevent paths
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# containing '..' in either the server or transport layers. (Also need to
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# consider what happens if someone creates a symlink pointing outside the
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# TODO: Server should rebase absolute paths coming across the network to put
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# them under the virtual root, if one is in use. LocalTransport currently
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# doesn't do that; if you give it an absolute path it just uses it.
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# XXX: Arguments can't contain newlines or ascii; possibly we should e.g.
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# urlescape them instead. Indeed possibly this should just literally be
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# TODO: Probably want some way for server commands to gradually produce body
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# data rather than passing it as a string; they could perhaps pass an
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# iterator-like callback that will gradually yield data; it probably needs a
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# close() method that will always be closed to do any necessary cleanup.
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# Promote some attributes from submodules into this namespace
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from bzrlib.smart.request import SmartServerRequestHandler