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Turn Backend into a sensible classoid.

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Nearly every part of the code that ever handles a full backend
structure has historically done it using a pair of pointer variables,
one pointing at a constant struct full of function pointers, and the
other pointing to a 'void *' state object that's passed to each of
those.

While I'm modernising the rest of the code, this seems like a good
time to turn that into the same more or less type-safe and less
cumbersome system as I'm using for other parts of the code, such as
Socket, Plug, BinaryPacketProtocol and so forth: the Backend structure
contains a vtable pointer, and a system of macro wrappers handles
dispatching through that vtable.
This commit is contained in:
Simon Tatham
2018-09-11 16:23:38 +01:00
parent c51fe7c217
commit eefebaaa9e
36 changed files with 633 additions and 611 deletions
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102
putty.h
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@ -441,43 +441,67 @@ enum {
ADDRTYPE_UNSPEC, ADDRTYPE_IPV4, ADDRTYPE_IPV6, ADDRTYPE_NAME
};
struct backend_tag {
const char *(*init) (void *frontend_handle, void **backend_handle,
struct Backend {
const Backend_vtable *vt;
};
struct Backend_vtable {
const char *(*init) (void *frontend_handle, Backend **backend_out,
Conf *conf, const char *host, int port,
char **realhost, int nodelay, int keepalive);
void (*free) (void *handle);
/* back->reconfig() passes in a replacement configuration. */
void (*reconfig) (void *handle, Conf *conf);
/* back->send() returns the current amount of buffered data. */
int (*send) (void *handle, const char *buf, int len);
/* back->sendbuffer() does the same thing but without attempting a send */
int (*sendbuffer) (void *handle);
void (*size) (void *handle, int width, int height);
void (*special) (void *handle, Telnet_Special code);
const struct telnet_special *(*get_specials) (void *handle);
int (*connected) (void *handle);
int (*exitcode) (void *handle);
/* If back->sendok() returns FALSE, data sent to it from the frontend
* may be lost. */
int (*sendok) (void *handle);
int (*ldisc) (void *handle, int);
void (*provide_ldisc) (void *handle, Ldisc *ldisc);
void (*provide_logctx) (void *handle, LogContext *logctx);
/*
* back->unthrottle() tells the back end that the front end
* buffer is clearing.
*/
void (*unthrottle) (void *handle, int);
int (*cfg_info) (void *handle);
void (*free) (Backend *be);
/* Pass in a replacement configuration. */
void (*reconfig) (Backend *be, Conf *conf);
/* send() returns the current amount of buffered data. */
int (*send) (Backend *be, const char *buf, int len);
/* sendbuffer() does the same thing but without attempting a send */
int (*sendbuffer) (Backend *be);
void (*size) (Backend *be, int width, int height);
void (*special) (Backend *be, Telnet_Special code);
const struct telnet_special *(*get_specials) (Backend *be);
int (*connected) (Backend *be);
int (*exitcode) (Backend *be);
/* If back->sendok() returns FALSE, the backend doesn't currently
* want input data, so the frontend should avoid acquiring any if
* possible (passing back-pressure on to its sender). */
int (*sendok) (Backend *be);
int (*ldisc_option_state) (Backend *be, int);
void (*provide_ldisc) (Backend *be, Ldisc *ldisc);
void (*provide_logctx) (Backend *be, LogContext *logctx);
/* Tells the back end that the front end buffer is clearing. */
void (*unthrottle) (Backend *be, int bufsize);
int (*cfg_info) (Backend *be);
/* Only implemented in the SSH protocol: check whether a
* connection-sharing upstream exists for a given configuration. */
int (*test_for_upstream)(const char *host, int port, Conf *conf);
const char *name;
int protocol;
int default_port;
};
extern Backend *backends[];
#define backend_init(vt, fe, out, conf, host, port, rhost, nd, ka) \
((vt)->init(fe, out, conf, host, port, rhost, nd, ka))
#define backend_free(be) ((be)->vt->free(be))
#define backend_reconfig(be, conf) ((be)->vt->reconfig(be, conf))
#define backend_send(be, buf, len) ((be)->vt->send(be, buf, len))
#define backend_sendbuffer(be) ((be)->vt->sendbuffer(be))
#define backend_size(be, w, h) ((be)->vt->size(be, w, h))
#define backend_special(be, code) ((be)->vt->special(be, code))
#define backend_get_specials(be) ((be)->vt->get_specials(be))
#define backend_connected(be) ((be)->vt->connected(be))
#define backend_exitcode(be) ((be)->vt->exitcode(be))
#define backend_sendok(be) ((be)->vt->sendok(be))
#define backend_ldisc_option_state(be, opt) \
((be)->vt->ldisc_option_state(be, opt))
#define backend_provide_ldisc(be, ldisc) ((be)->vt->provide_ldisc(be, ldisc))
#define backend_provide_logctx(be, logctx) \
((be)->vt->provide_logctx(be, logctx))
#define backend_unthrottle(be, bufsize) ((be)->vt->unthrottle(be, bufsize))
#define backend_cfg_info(be) ((be)->vt->cfg_info(be))
extern const struct Backend_vtable *const backends[];
/*
* Suggested default protocol provided by the backend link module.
@ -1046,8 +1070,8 @@ void random_destroy_seed(void);
/*
* Exports from settings.c.
*/
Backend *backend_from_name(const char *name);
Backend *backend_from_proto(int proto);
const struct Backend_vtable *backend_vt_from_name(const char *name);
const struct Backend_vtable *backend_vt_from_proto(int proto);
char *get_remote_username(Conf *conf); /* dynamically allocated */
char *save_settings(const char *section, Conf *conf);
void save_open_settings(void *sesskey, Conf *conf);
@ -1107,9 +1131,7 @@ void term_request_paste(Terminal *, int clipboard);
void term_seen_key_event(Terminal *);
int term_data(Terminal *, int is_stderr, const void *data, int len);
int term_data_untrusted(Terminal *, const void *data, int len);
void term_provide_resize_fn(Terminal *term,
void (*resize_fn)(void *, int, int),
void *resize_ctx);
void term_provide_backend(Terminal *term, Backend *backend);
void term_provide_logctx(Terminal *term, LogContext *logctx);
void term_set_focus(Terminal *term, int has_focus);
char *term_get_ttymode(Terminal *term, const char *mode);
@ -1145,36 +1167,36 @@ void log_packet(LogContext *logctx, int direction, int type,
* Exports from testback.c
*/
extern Backend null_backend;
extern Backend loop_backend;
extern const struct Backend_vtable null_backend;
extern const struct Backend_vtable loop_backend;
/*
* Exports from raw.c.
*/
extern Backend raw_backend;
extern const struct Backend_vtable raw_backend;
/*
* Exports from rlogin.c.
*/
extern Backend rlogin_backend;
extern const struct Backend_vtable rlogin_backend;
/*
* Exports from telnet.c.
*/
extern Backend telnet_backend;
extern const struct Backend_vtable telnet_backend;
/*
* Exports from ssh.c.
*/
extern Backend ssh_backend;
extern const struct Backend_vtable ssh_backend;
/*
* Exports from ldisc.c.
*/
Ldisc *ldisc_create(Conf *, Terminal *, Backend *, void *, void *);
Ldisc *ldisc_create(Conf *, Terminal *, Backend *, void *);
void ldisc_configure(Ldisc *, Conf *);
void ldisc_free(Ldisc *);
void ldisc_send(Ldisc *, const void *buf, int len, int interactive);
@ -1205,7 +1227,7 @@ void random_unref(void);
* Exports from pinger.c.
*/
typedef struct pinger_tag *Pinger;
Pinger pinger_new(Conf *conf, Backend *back, void *backhandle);
Pinger pinger_new(Conf *conf, Backend *backend);
void pinger_reconfig(Pinger, Conf *oldconf, Conf *newconf);
void pinger_free(Pinger);