mirror of
https://git.tartarus.org/simon/putty.git
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807ed08da0
In the previous few commits I noticed some repeated work in the form of pointless empty implementations of Plug's log method, plus some existing (and some new) empty cases of Socket's endpoint_info. As a cleanup, I'm replacing as many as I can find with uses of a central null implementation in the stubs directory.
445 lines
18 KiB
C
445 lines
18 KiB
C
/*
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* Networking abstraction in PuTTY.
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*
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* The way this works is: a back end can choose to open any number
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* of sockets - including zero, which might be necessary in some.
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* It can register a bunch of callbacks (most notably for when
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* data is received) for each socket, and it can call the networking
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* abstraction to send data without having to worry about blocking.
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* The stuff behind the abstraction takes care of selects and
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* nonblocking writes and all that sort of painful gubbins.
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*/
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#ifndef PUTTY_NETWORK_H
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#define PUTTY_NETWORK_H
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#include "defs.h"
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typedef struct SocketVtable SocketVtable;
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typedef struct PlugVtable PlugVtable;
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struct Socket {
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const struct SocketVtable *vt;
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};
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struct SocketVtable {
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Plug *(*plug) (Socket *s, Plug *p);
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/* use a different plug (return the old one) */
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/* if p is NULL, it doesn't change the plug */
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/* but it does return the one it's using */
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void (*close) (Socket *s);
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size_t (*write) (Socket *s, const void *data, size_t len);
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size_t (*write_oob) (Socket *s, const void *data, size_t len);
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void (*write_eof) (Socket *s);
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void (*set_frozen) (Socket *s, bool is_frozen);
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/* ignored by tcp, but vital for ssl */
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const char *(*socket_error) (Socket *s);
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SocketEndpointInfo *(*endpoint_info) (Socket *s, bool peer);
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};
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typedef union { void *p; int i; } accept_ctx_t;
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typedef Socket *(*accept_fn_t)(accept_ctx_t ctx, Plug *plug);
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struct Plug {
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const struct PlugVtable *vt;
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};
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typedef enum PlugLogType {
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PLUGLOG_CONNECT_TRYING,
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PLUGLOG_CONNECT_FAILED,
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PLUGLOG_CONNECT_SUCCESS,
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PLUGLOG_PROXY_MSG,
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} PlugLogType;
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typedef enum PlugCloseType {
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PLUGCLOSE_NORMAL,
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PLUGCLOSE_ERROR,
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PLUGCLOSE_BROKEN_PIPE,
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PLUGCLOSE_USER_ABORT,
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} PlugCloseType;
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struct PlugVtable {
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/*
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* Passes the client progress reports on the process of setting
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* up the connection.
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*
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* - PLUGLOG_CONNECT_TRYING means we are about to try to connect
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* to address `addr' (error_msg and error_code are ignored)
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*
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* - PLUGLOG_CONNECT_FAILED means we have failed to connect to
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* address `addr' (error_msg and error_code are supplied). This
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* is not a fatal error - we may well have other candidate
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* addresses to fall back to. When it _is_ fatal, the closing()
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* function will be called.
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*
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* - PLUGLOG_CONNECT_SUCCESS means we have succeeded in making a
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* connection. `addr' gives the address we connected to, if
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* available. (But sometimes, in cases of complicated proxy
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* setups, it might not be available, so receivers of this log
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* event should be prepared to deal with addr==NULL.)
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*
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* - PLUGLOG_PROXY_MSG means that error_msg contains a line of
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* logging information from whatever the connection is being
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* proxied through. This will typically be a wodge of
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* standard-error output from a local proxy command, so the
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* receiver should probably prefix it to indicate this.
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*
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* Note that sometimes log messages may be sent even to Socket
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* types that don't involve making an outgoing connection, e.g.
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* because the same core implementation (such as Windows handle
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* sockets) is shared between listening and connecting sockets. So
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* all Plugs must implement this method, even if only to ignore
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* the logged events.
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*/
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void (*log)(Plug *p, Socket *s, PlugLogType type, SockAddr *addr, int port,
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const char *error_msg, int error_code);
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/*
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* Notifies the Plug that the socket is closing, and something
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* about why.
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*
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* - PLUGCLOSE_NORMAL means an ordinary non-error closure. In
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* this case, error_msg should be ignored (and hopefully
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* callers will have passed NULL).
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*
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* - PLUGCLOSE_ERROR indicates that an OS error occurred, and
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* 'error_msg' contains a string describing it, for use in
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* diagnostics. (Ownership of the string is not transferred.)
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* This error class covers anything other than the special
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* case below:
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*
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* - PLUGCLOSE_BROKEN_PIPE behaves like PLUGCLOSE_ERROR (in
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* particular, there's still an error message provided), but
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* distinguishes the particular error condition signalled by
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* EPIPE / ERROR_BROKEN_PIPE, which ssh/sharing.c needs to
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* recognise and handle specially in one situation.
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*
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* - PLUGCLOSE_USER_ABORT means that the close has happened as a
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* result of some kind of deliberate user action (e.g. hitting
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* ^C at a password prompt presented by a proxy socket setup
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* phase). This can be used to suppress interactive error
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* messages sent to the user (such as dialog boxes), on the
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* grounds that the user already knows. However, 'error_msg'
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* will still contain some appropriate text, so that
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* non-interactive error reporting (e.g. event logs) can still
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* record why the connection terminated.
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*/
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void (*closing)(Plug *p, PlugCloseType type, const char *error_msg);
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/*
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* Provides incoming socket data to the Plug. Three cases:
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*
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* - urgent==0. `data' points to `len' bytes of perfectly
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* ordinary data.
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*
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* - urgent==1. `data' points to `len' bytes of data,
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* which were read from before an Urgent pointer.
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*
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* - urgent==2. `data' points to `len' bytes of data,
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* the first of which was the one at the Urgent mark.
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*/
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void (*receive) (Plug *p, int urgent, const char *data, size_t len);
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/*
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* Called when the pending send backlog on a socket is cleared or
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* partially cleared. The new backlog size is passed in the
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* `bufsize' parameter.
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*/
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void (*sent) (Plug *p, size_t bufsize);
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/*
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* Only called on listener-type sockets, and is passed a
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* constructor function+context that will create a fresh Socket
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* describing the connection. It returns nonzero if it doesn't
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* want the connection for some reason, or 0 on success.
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*/
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int (*accepting)(Plug *p, accept_fn_t constructor, accept_ctx_t ctx);
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};
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/* Proxy indirection layer.
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*
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* Calling new_connection transfers ownership of 'addr': the proxy
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* layer is now responsible for freeing it, and the caller shouldn't
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* assume it exists any more.
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*
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* If calling this from a backend with a Seat, you can also give it a
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* pointer to the backend's Interactor trait. In that situation, it
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* might replace the backend's seat with a temporary seat of its own,
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* and give the real Seat to an Interactor somewhere in the proxy
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* system so that it can ask for passwords (and, in the case of SSH
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* proxying, other prompts like host key checks). If that happens,
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* then the resulting 'temp seat' is the backend's property, and it
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* will have to remember to free it when cleaning up, or after
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* flushing it back into the real seat when the network connection
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* attempt completes.
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*
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* You can free your TempSeat and resume using the real Seat when one
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* of two things happens: either your Plug's closing() method is
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* called (indicating failure to connect), or its log() method is
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* called with PLUGLOG_CONNECT_SUCCESS. In the latter case, you'll
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* probably want to flush the TempSeat's contents into the real Seat,
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* of course.
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*/
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Socket *new_connection(SockAddr *addr, const char *hostname,
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int port, bool privport,
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bool oobinline, bool nodelay, bool keepalive,
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Plug *plug, Conf *conf, Interactor *interactor);
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Socket *new_listener(const char *srcaddr, int port, Plug *plug,
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bool local_host_only, Conf *conf, int addressfamily);
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SockAddr *name_lookup(const char *host, int port, char **canonicalname,
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Conf *conf, int addressfamily, LogContext *logctx,
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const char *lookup_reason_for_logging);
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/* platform-dependent callback from new_connection() */
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/* (same caveat about addr as new_connection()) */
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Socket *platform_new_connection(SockAddr *addr, const char *hostname,
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int port, bool privport,
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bool oobinline, bool nodelay, bool keepalive,
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Plug *plug, Conf *conf, Interactor *itr);
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/* callback for SSH jump-host proxying */
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Socket *sshproxy_new_connection(SockAddr *addr, const char *hostname,
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int port, bool privport,
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bool oobinline, bool nodelay, bool keepalive,
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Plug *plug, Conf *conf, Interactor *itr);
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/* socket functions */
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void sk_init(void); /* called once at program startup */
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void sk_cleanup(void); /* called just before program exit */
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SockAddr *sk_namelookup(const char *host, char **canonicalname, int address_family);
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SockAddr *sk_nonamelookup(const char *host);
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void sk_getaddr(SockAddr *addr, char *buf, int buflen);
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bool sk_addr_needs_port(SockAddr *addr);
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bool sk_hostname_is_local(const char *name);
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bool sk_address_is_local(SockAddr *addr);
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bool sk_address_is_special_local(SockAddr *addr);
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int sk_addrtype(SockAddr *addr);
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void sk_addrcopy(SockAddr *addr, char *buf);
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void sk_addr_free(SockAddr *addr);
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/* sk_addr_dup generates another SockAddr which contains the same data
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* as the original one and can be freed independently. May not actually
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* physically _duplicate_ it: incrementing a reference count so that
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* one more free is required before it disappears is an acceptable
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* implementation. */
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SockAddr *sk_addr_dup(SockAddr *addr);
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/* NB, control of 'addr' is passed via sk_new, which takes responsibility
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* for freeing it, as for new_connection() */
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Socket *sk_new(SockAddr *addr, int port, bool privport, bool oobinline,
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bool nodelay, bool keepalive, Plug *p);
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Socket *sk_newlistener(const char *srcaddr, int port, Plug *plug,
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bool local_host_only, int address_family);
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static inline Plug *sk_plug(Socket *s, Plug *p)
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{ return s->vt->plug(s, p); }
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static inline void sk_close(Socket *s)
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{ s->vt->close(s); }
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static inline size_t sk_write(Socket *s, const void *data, size_t len)
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{ return s->vt->write(s, data, len); }
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static inline size_t sk_write_oob(Socket *s, const void *data, size_t len)
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{ return s->vt->write_oob(s, data, len); }
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static inline void sk_write_eof(Socket *s)
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{ s->vt->write_eof(s); }
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static inline void plug_log(
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Plug *p, Socket *s, int type, SockAddr *addr, int port,
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const char *msg, int code)
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{ p->vt->log(p, s, type, addr, port, msg, code); }
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static inline void plug_closing(Plug *p, PlugCloseType type, const char *msg)
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{ p->vt->closing(p, type, msg); }
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static inline void plug_closing_normal(Plug *p)
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{ p->vt->closing(p, PLUGCLOSE_NORMAL, NULL); }
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static inline void plug_closing_error(Plug *p, const char *msg)
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{ p->vt->closing(p, PLUGCLOSE_ERROR, msg); }
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static inline void plug_closing_user_abort(Plug *p)
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{ p->vt->closing(p, PLUGCLOSE_USER_ABORT, "User aborted connection setup"); }
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static inline void plug_receive(Plug *p, int urg, const char *data, size_t len)
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{ p->vt->receive(p, urg, data, len); }
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static inline void plug_sent (Plug *p, size_t bufsize)
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{ p->vt->sent(p, bufsize); }
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static inline int plug_accepting(Plug *p, accept_fn_t cons, accept_ctx_t ctx)
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{ return p->vt->accepting(p, cons, ctx); }
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/*
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* Special error values are returned from sk_namelookup and sk_new
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* if there's a problem. These functions extract an error message,
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* or return NULL if there's no problem.
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*/
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const char *sk_addr_error(SockAddr *addr);
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static inline const char *sk_socket_error(Socket *s)
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{ return s->vt->socket_error(s); }
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/*
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* Set the `frozen' flag on a socket. A frozen socket is one in
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* which all READABLE notifications are ignored, so that data is
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* not accepted from the peer until the socket is unfrozen. This
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* exists for two purposes:
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*
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* - Port forwarding: when a local listening port receives a
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* connection, we do not want to receive data from the new
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* socket until we have somewhere to send it. Hence, we freeze
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* the socket until its associated SSH channel is ready; then we
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* unfreeze it and pending data is delivered.
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*
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* - Socket buffering: if an SSH channel (or the whole connection)
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* backs up or presents a zero window, we must freeze the
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* associated local socket in order to avoid unbounded buffer
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* growth.
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*/
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static inline void sk_set_frozen(Socket *s, bool is_frozen)
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{ s->vt->set_frozen(s, is_frozen); }
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/*
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* Return a structure giving some information about one end of
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* the socket. May be NULL, if nothing is available at all. If it is
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* not NULL, then it is dynamically allocated, and should be freed by
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* a call to sk_free_endpoint_info(). See below for the definition.
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*/
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static inline SocketEndpointInfo *sk_endpoint_info(Socket *s, bool peer)
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{ return s->vt->endpoint_info(s, peer); }
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static inline SocketEndpointInfo *sk_peer_info(Socket *s)
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{ return sk_endpoint_info(s, true); }
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/*
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* The structure returned from sk_endpoint_info, and a function to free
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* one (in utils).
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*/
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struct SocketEndpointInfo {
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int addressfamily;
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/*
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* Text form of the IPv4 or IPv6 address of the specified end of the
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* socket, if available, in the standard text representation.
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*/
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const char *addr_text;
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/*
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* Binary form of the same address. Filled in if and only if
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* addr_text is not NULL. You can tell which branch of the union
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* is used by examining 'addressfamily'.
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*/
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union {
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unsigned char ipv6[16];
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unsigned char ipv4[4];
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} addr_bin;
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/*
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* Remote port number, or -1 if not available.
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*/
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int port;
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/*
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* Free-form text suitable for putting in log messages. For IP
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* sockets, repeats the address and port information from above.
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* But it can be completely different, e.g. for Unix-domain
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* sockets it gives information about the uid, gid and pid of the
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* connecting process.
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*/
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const char *log_text;
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};
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void sk_free_endpoint_info(SocketEndpointInfo *ei);
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/*
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* Simple wrapper on getservbyname(), needed by portfwd.c. Returns the
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* port number, in host byte order (suitable for printf and so on).
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* Returns 0 on failure. Any platform not supporting getservbyname
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* can just return 0 - this function is not required to handle
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* numeric port specifications.
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*/
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int net_service_lookup(const char *service);
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/*
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* Look up the local hostname; return value needs freeing.
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* May return NULL.
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*/
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char *get_hostname(void);
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/*
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* Trivial socket implementation which just stores an error. Found in
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* errsock.c.
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*
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* The consume_string variant takes an already-formatted dynamically
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* allocated string, and takes over ownership of that string.
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*/
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Socket *new_error_socket_fmt(Plug *plug, const char *fmt, ...)
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PRINTF_LIKE(2, 3);
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Socket *new_error_socket_consume_string(Plug *plug, char *errmsg);
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/*
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* Trivial plug that does absolutely nothing. Found in nullplug.c.
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*/
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extern Plug *const nullplug;
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/*
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* Some trivial no-op plug functions, also in nullplug.c; exposed here
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* so that other Plug implementations can use them too.
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*
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* In particular, nullplug_log is useful to Plugs that don't need to
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* worry about logging.
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*/
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void nullplug_log(Plug *plug, Socket *s, PlugLogType type, SockAddr *addr,
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int port, const char *err_msg, int err_code);
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void nullplug_closing(Plug *plug, PlugCloseType type, const char *error_msg);
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void nullplug_receive(Plug *plug, int urgent, const char *data, size_t len);
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void nullplug_sent(Plug *plug, size_t bufsize);
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/*
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* Similar no-op socket function.
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*/
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SocketEndpointInfo *nullsock_endpoint_info(Socket *s, bool peer);
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/* ----------------------------------------------------------------------
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* Functions defined outside the network code, which have to be
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* declared in this header file rather than the main putty.h because
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* they use types defined here.
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*/
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void backend_socket_log(Seat *seat, LogContext *logctx, Socket *sock,
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PlugLogType type, SockAddr *addr, int port,
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const char *error_msg, int error_code, Conf *conf,
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bool session_started);
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typedef struct ProxyStderrBuf {
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char buf[8192];
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size_t size;
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const char *prefix; /* must be statically allocated */
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} ProxyStderrBuf;
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void psb_init(ProxyStderrBuf *psb);
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void psb_set_prefix(ProxyStderrBuf *psb, const char *prefix);
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void log_proxy_stderr(Plug *plug, Socket *sock, ProxyStderrBuf *psb,
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const void *vdata, size_t len);
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/* ----------------------------------------------------------------------
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* The DeferredSocketOpener trait. This is a thing that some Socket
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* implementations may choose to own if they need to delay actually
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* setting up the underlying connection. For example, sockets used in
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* local-proxy handling (Unix FdSocket / Windows HandleSocket) might
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* need to do this if they have to prompt the user interactively for
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* parts of the command they'll run.
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*
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* Mostly, a DeferredSocketOpener implementation will keep to itself,
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* arrange its own callbacks in order to do whatever setup it needs,
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* and when it's ready, call back to its parent Socket via some
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* implementation-specific API of its own. So the shared API here
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* requires almost nothing: the only thing we need is a free function,
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* so that if the owner of a Socket of this kind needs to close it
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* before the deferred connection process is finished, the Socket can
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* also clean up the DeferredSocketOpener dangling off it.
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*/
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struct DeferredSocketOpener {
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const DeferredSocketOpenerVtable *vt;
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};
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struct DeferredSocketOpenerVtable {
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void (*free)(DeferredSocketOpener *);
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};
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static inline void deferred_socket_opener_free(DeferredSocketOpener *dso)
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{ dso->vt->free(dso); }
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DeferredSocketOpener *null_deferred_socket_opener(void);
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#endif
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