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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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69
telnet.c
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@ -117,8 +117,6 @@ static const char *telopt(int opt)
#undef telnet_str
}
static void telnet_size(void *handle, int width, int height);
struct Opt {
int send; /* what we initially send */
int nsend; /* -ve send if requested to stop it */
@ -199,6 +197,7 @@ typedef struct telnet_tag {
Pinger pinger;
const Plug_vtable *plugvt;
Backend backend;
} *Telnet;
#define TELNET_MAX_BACKLOG 4096
@ -280,7 +279,8 @@ static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
static void activate_option(Telnet telnet, const struct Opt *o)
{
if (o->send == WILL && o->option == TELOPT_NAWS)
telnet_size(telnet, telnet->term_width, telnet->term_height);
backend_size(&telnet->backend,
telnet->term_width, telnet->term_height);
if (o->send == WILL &&
(o->option == TELOPT_NEW_ENVIRON ||
o->option == TELOPT_OLD_ENVIRON)) {
@ -705,7 +705,7 @@ static const Plug_vtable Telnet_plugvt = {
* Also places the canonical host name into `realhost'. It must be
* freed by the caller.
*/
static const char *telnet_init(void *frontend_handle, void **backend_handle,
static const char *telnet_init(void *frontend_handle, Backend **backend_handle,
Conf *conf, const char *host, int port,
char **realhost, int nodelay, int keepalive)
{
@ -717,6 +717,7 @@ static const char *telnet_init(void *frontend_handle, void **backend_handle,
telnet = snew(struct telnet_tag);
telnet->plugvt = &Telnet_plugvt;
telnet->backend.vt = &telnet_backend;
telnet->conf = conf_copy(conf);
telnet->s = NULL;
telnet->closed_on_socket_error = FALSE;
@ -732,7 +733,7 @@ static const char *telnet_init(void *frontend_handle, void **backend_handle,
telnet->ldisc = NULL;
telnet->pinger = NULL;
telnet->session_started = TRUE;
*backend_handle = telnet;
*backend_handle = &telnet->backend;
/*
* Try to find host.
@ -756,7 +757,7 @@ static const char *telnet_init(void *frontend_handle, void **backend_handle,
if ((err = sk_socket_error(telnet->s)) != NULL)
return err;
telnet->pinger = pinger_new(telnet->conf, &telnet_backend, telnet);
telnet->pinger = pinger_new(telnet->conf, &telnet->backend);
/*
* Initialise option states.
@ -805,9 +806,9 @@ static const char *telnet_init(void *frontend_handle, void **backend_handle,
return NULL;
}
static void telnet_free(void *handle)
static void telnet_free(Backend *be)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
sfree(telnet->sb_buf);
if (telnet->s)
@ -822,9 +823,9 @@ static void telnet_free(void *handle)
* necessary, in this backend: we just save the fresh config for
* any subsequent negotiations.
*/
static void telnet_reconfig(void *handle, Conf *conf)
static void telnet_reconfig(Backend *be, Conf *conf)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
pinger_reconfig(telnet->pinger, telnet->conf, conf);
conf_free(telnet->conf);
telnet->conf = conf_copy(conf);
@ -833,9 +834,9 @@ static void telnet_reconfig(void *handle, Conf *conf)
/*
* Called to send data down the Telnet connection.
*/
static int telnet_send(void *handle, const char *buf, int len)
static int telnet_send(Backend *be, const char *buf, int len)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
unsigned char *p, *end;
static const unsigned char iac[2] = { IAC, IAC };
static const unsigned char cr[2] = { CR, NUL };
@ -868,18 +869,18 @@ static int telnet_send(void *handle, const char *buf, int len)
/*
* Called to query the current socket sendability status.
*/
static int telnet_sendbuffer(void *handle)
static int telnet_sendbuffer(Backend *be)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
return telnet->bufsize;
}
/*
* Called to set the size of the window from Telnet's POV.
*/
static void telnet_size(void *handle, int width, int height)
static void telnet_size(Backend *be, int width, int height)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
unsigned char b[24];
int n;
char *logbuf;
@ -913,9 +914,9 @@ static void telnet_size(void *handle, int width, int height)
/*
* Send Telnet special codes.
*/
static void telnet_special(void *handle, Telnet_Special code)
static void telnet_special(Backend *be, Telnet_Special code)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
unsigned char b[2];
if (telnet->s == NULL)
@ -1008,7 +1009,7 @@ static void telnet_special(void *handle, Telnet_Special code)
}
}
static const struct telnet_special *telnet_get_specials(void *handle)
static const struct telnet_special *telnet_get_specials(Backend *be)
{
static const struct telnet_special specials[] = {
{"Are You There", TS_AYT},
@ -1031,27 +1032,27 @@ static const struct telnet_special *telnet_get_specials(void *handle)
return specials;
}
static int telnet_connected(void *handle)
static int telnet_connected(Backend *be)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
return telnet->s != NULL;
}
static int telnet_sendok(void *handle)
static int telnet_sendok(Backend *be)
{
/* Telnet telnet = (Telnet) handle; */
/* Telnet telnet = FROMFIELD(be, struct telnet_tag, backend); */
return 1;
}
static void telnet_unthrottle(void *handle, int backlog)
static void telnet_unthrottle(Backend *be, int backlog)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
}
static int telnet_ldisc(void *handle, int option)
static int telnet_ldisc(Backend *be, int option)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
if (option == LD_ECHO)
return telnet->echoing;
if (option == LD_EDIT)
@ -1059,20 +1060,20 @@ static int telnet_ldisc(void *handle, int option)
return FALSE;
}
static void telnet_provide_ldisc(void *handle, Ldisc *ldisc)
static void telnet_provide_ldisc(Backend *be, Ldisc *ldisc)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
telnet->ldisc = ldisc;
}
static void telnet_provide_logctx(void *handle, LogContext *logctx)
static void telnet_provide_logctx(Backend *be, LogContext *logctx)
{
/* This is a stub. */
}
static int telnet_exitcode(void *handle)
static int telnet_exitcode(Backend *be)
{
Telnet telnet = (Telnet) handle;
Telnet telnet = FROMFIELD(be, struct telnet_tag, backend);
if (telnet->s != NULL)
return -1; /* still connected */
else if (telnet->closed_on_socket_error)
@ -1085,12 +1086,12 @@ static int telnet_exitcode(void *handle)
/*
* cfg_info for Telnet does nothing at all.
*/
static int telnet_cfg_info(void *handle)
static int telnet_cfg_info(Backend *be)
{
return 0;
}
Backend telnet_backend = {
const struct Backend_vtable telnet_backend = {
telnet_init,
telnet_free,
telnet_reconfig,