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cd97b7e7ea
Ever since I reworked the SSH code to have multiple internal packet queues, there's been a long-standing FIXME in ssh_sendbuffer() saying that we ought to include the data buffered in those queues as part of reporting how much data is buffered on standard input. Recently a user reported that 'proftpd', or rather its 'mod_sftp' add-on that implements an SFTP-only SSH server, exposes a bug related to that missing piece of code. The xfer_upload system in sftp.c starts by pushing SFTP write messages into the SSH code for as long as sftp_sendbuffer() (which ends up at ssh_sendbuffer()) reports that not too much data is buffered locally. In fact what happens is that all those messages end up on the packet queues between SSH protocol layers, so they're not counted by sftp_sendbuffer(), so we just keep going until there's some other reason to stop. Usually the reason we stop is because we've filled up the SFTP channel's SSH-layer window, so we need the server to send us a WINDOW_ADJUST before we're allowed to send any more data. So we return to the main event loop and start waiting for reply packets. And when the window is moderate (e.g. OpenSSH currently seems to present about 2MB), this isn't really noticeable. But proftpd presents the maximum-size window of 2^32-1 bytes, and as a result we just keep shovelling more and more packets into the internal packet queues until PSFTP has grown to 4GB in size, and only then do we even return to the event loop and start actually sending them down the network. Moreover, this happens again at rekey time, because while a rekey is in progress, ssh2transport stops emptying the queue of outgoing packets sent by its higher layer - so, again, everything just keeps buffering up somewhere that sftp_sendbuffer can't see it. But this commit fixes it! Each PacketProtocolLayer now provides a vtable method for asking how much data it currently has queued. Most of them share a default implementation which just returns the newly added total_size field from their pq_out; the exception is ssh2transport, which also has to account for data queued in its higher layer. And ssh_sendbuffer() adds that on to the quantity it already knew about in other locations, to give a more realistic idea of the currently buffered data.
174 lines
7.4 KiB
C
174 lines
7.4 KiB
C
/*
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* Abstraction of the various layers of SSH packet-level protocol,
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* general enough to take in all three of the main SSH-2 layers and
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* both of the SSH-1 phases.
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*/
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#ifndef PUTTY_SSHPPL_H
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#define PUTTY_SSHPPL_H
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typedef void (*packet_handler_fn_t)(PacketProtocolLayer *ppl, PktIn *pktin);
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struct PacketProtocolLayerVtable {
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void (*free)(PacketProtocolLayer *);
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void (*process_queue)(PacketProtocolLayer *ppl);
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bool (*get_specials)(
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PacketProtocolLayer *ppl, add_special_fn_t add_special, void *ctx);
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void (*special_cmd)(
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PacketProtocolLayer *ppl, SessionSpecialCode code, int arg);
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bool (*want_user_input)(PacketProtocolLayer *ppl);
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void (*got_user_input)(PacketProtocolLayer *ppl);
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void (*reconfigure)(PacketProtocolLayer *ppl, Conf *conf);
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size_t (*queued_data_size)(PacketProtocolLayer *ppl);
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/* Protocol-level name of this layer. */
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const char *name;
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};
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struct PacketProtocolLayer {
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const struct PacketProtocolLayerVtable *vt;
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/* Link to the underlying SSH BPP. */
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BinaryPacketProtocol *bpp;
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/* Queue from which the layer receives its input packets, and one
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* to put its output packets on. */
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PktInQueue *in_pq;
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PktOutQueue *out_pq;
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/* Idempotent callback that in_pq will be linked to, causing a
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* call to the process_queue method. in_pq points to this, so it
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* will be automatically triggered by pushing things on the
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* layer's input queue, but it can also be triggered on purpose. */
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IdempotentCallback ic_process_queue;
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/* Owner's pointer to this layer. Permits a layer to unilaterally
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* abdicate in favour of a replacement, by overwriting this
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* pointer and then freeing itself. */
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PacketProtocolLayer **selfptr;
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/* Bufchain of keyboard input from the user, for login prompts and
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* similar. */
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bufchain *user_input;
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/* Logging and error-reporting facilities. */
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LogContext *logctx;
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Seat *seat; /* for dialog boxes, session output etc */
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Ssh *ssh; /* for session termination + assorted connection-layer ops */
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/* Known bugs in the remote implementation. */
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unsigned remote_bugs;
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};
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static inline void ssh_ppl_process_queue(PacketProtocolLayer *ppl)
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{ ppl->vt->process_queue(ppl); }
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static inline bool ssh_ppl_get_specials(
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PacketProtocolLayer *ppl, add_special_fn_t add_special, void *ctx)
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{ return ppl->vt->get_specials(ppl, add_special, ctx); }
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static inline void ssh_ppl_special_cmd(
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PacketProtocolLayer *ppl, SessionSpecialCode code, int arg)
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{ ppl->vt->special_cmd(ppl, code, arg); }
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static inline bool ssh_ppl_want_user_input(PacketProtocolLayer *ppl)
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{ return ppl->vt->want_user_input(ppl); }
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static inline void ssh_ppl_got_user_input(PacketProtocolLayer *ppl)
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{ ppl->vt->got_user_input(ppl); }
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static inline void ssh_ppl_reconfigure(PacketProtocolLayer *ppl, Conf *conf)
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{ ppl->vt->reconfigure(ppl, conf); }
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static inline size_t ssh_ppl_queued_data_size(PacketProtocolLayer *ppl)
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{ return ppl->vt->queued_data_size(ppl); }
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/* ssh_ppl_free is more than just a macro wrapper on the vtable; it
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* does centralised parts of the freeing too. */
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void ssh_ppl_free(PacketProtocolLayer *ppl);
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/* Helper routine to point a PPL at its input and output queues. Also
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* sets up the IdempotentCallback on the input queue to trigger a call
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* to process_queue whenever packets are added to it. */
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void ssh_ppl_setup_queues(PacketProtocolLayer *ppl,
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PktInQueue *inq, PktOutQueue *outq);
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/* Routine a PPL can call to abdicate in favour of a replacement, by
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* overwriting ppl->selfptr. Has the side effect of freeing 'old', so
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* if 'old' actually called this (which is likely) then it should
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* avoid dereferencing itself on return from this function! */
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void ssh_ppl_replace(PacketProtocolLayer *old, PacketProtocolLayer *new);
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/* Default implementation of queued_data_size, which just adds up the
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* sizes of all the packets in pq_out. A layer can override this if it
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* has other things to take into account as well. */
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size_t ssh_ppl_default_queued_data_size(PacketProtocolLayer *ppl);
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PacketProtocolLayer *ssh1_login_new(
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Conf *conf, const char *host, int port,
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PacketProtocolLayer *successor_layer);
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PacketProtocolLayer *ssh1_connection_new(
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Ssh *ssh, Conf *conf, ConnectionLayer **cl_out);
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struct DataTransferStats;
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struct ssh_connection_shared_gss_state;
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PacketProtocolLayer *ssh2_transport_new(
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Conf *conf, const char *host, int port, const char *fullhostname,
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const char *client_greeting, const char *server_greeting,
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struct ssh_connection_shared_gss_state *shgss,
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struct DataTransferStats *stats, PacketProtocolLayer *higher_layer,
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const SshServerConfig *ssc);
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PacketProtocolLayer *ssh2_userauth_new(
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PacketProtocolLayer *successor_layer,
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const char *hostname, const char *fullhostname,
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Filename *keyfile, bool show_banner, bool tryagent,
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const char *default_username, bool change_username,
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bool try_ki_auth,
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bool try_gssapi_auth, bool try_gssapi_kex_auth,
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bool gssapi_fwd, struct ssh_connection_shared_gss_state *shgss);
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PacketProtocolLayer *ssh2_connection_new(
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Ssh *ssh, ssh_sharing_state *connshare, bool is_simple,
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Conf *conf, const char *peer_verstring, ConnectionLayer **cl_out);
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/* Can't put this in the userauth constructor without having a
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* dependency loop at setup time (transport and userauth can't _both_
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* be constructed second and given a pointer to the other). */
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void ssh2_userauth_set_transport_layer(PacketProtocolLayer *userauth,
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PacketProtocolLayer *transport);
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/* Convenience macro for protocol layers to send formatted strings to
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* the Event Log. Assumes a function parameter called 'ppl' is in
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* scope. */
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#define ppl_logevent(...) ( \
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logevent_and_free((ppl)->logctx, dupprintf(__VA_ARGS__)))
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/* Convenience macro for protocol layers to send formatted strings to
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* the terminal. Also expects 'ppl' to be in scope. */
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#define ppl_printf(...) \
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ssh_ppl_user_output_string_and_free(ppl, dupprintf(__VA_ARGS__))
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void ssh_ppl_user_output_string_and_free(PacketProtocolLayer *ppl, char *text);
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/* Methods for userauth to communicate back to the transport layer */
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ptrlen ssh2_transport_get_session_id(PacketProtocolLayer *ssh2_transport_ptr);
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void ssh2_transport_notify_auth_done(PacketProtocolLayer *ssh2_transport_ptr);
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/* Shared method between ssh2 layers (defined in ssh2transport.c) to
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* handle the common packets between login and connection: DISCONNECT,
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* DEBUG and IGNORE. Those messages are handled by the ssh2transport
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* layer if we have one, but in bare ssh2-connection mode they have to
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* be handled by ssh2connection. */
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bool ssh2_common_filter_queue(PacketProtocolLayer *ppl);
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/* Methods for ssh1login to pass protocol flags to ssh1connection */
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void ssh1_connection_set_protoflags(
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PacketProtocolLayer *ppl, int local, int remote);
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/* Shared get_specials method between the two ssh1 layers */
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bool ssh1_common_get_specials(PacketProtocolLayer *, add_special_fn_t, void *);
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/* Other shared functions between ssh1 layers */
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bool ssh1_common_filter_queue(PacketProtocolLayer *ppl);
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void ssh1_compute_session_id(
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unsigned char *session_id, const unsigned char *cookie,
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RSAKey *hostkey, RSAKey *servkey);
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/* Method used by the SSH server */
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void ssh2_transport_provide_hostkeys(PacketProtocolLayer *ssh2_transport_ptr,
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ssh_key *const *hostkeys, int nhostkeys);
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#endif /* PUTTY_SSHPPL_H */
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