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New abstraction 'Seat', to pass to backends.

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This is a new vtable-based abstraction which is passed to a backend in
place of Frontend, and it implements only the subset of the Frontend
functions needed by a backend. (Many other Frontend functions still
exist, notably the wide range of things called by terminal.c providing
platform-independent operations on the GUI terminal window.)

The purpose of making it a vtable is that this opens up the
possibility of creating a backend as an internal implementation detail
of some other activity, by providing just that one backend with a
custom Seat that implements the methods differently.

For example, this refactoring should make it feasible to directly
implement an SSH proxy type, aka the 'jump host' feature supported by
OpenSSH, aka 'open a secondary SSH session in MAINCHAN_DIRECT_TCP
mode, and then expose the main channel of that as the Socket for the
primary connection'. (Which of course you can already do by spawning
'plink -nc' as a separate proxy process, but this would permit it in
the _same_ process without anything getting confused.)

I've centralised a full set of stub methods in misc.c for the new
abstraction, which allows me to get rid of several annoying stubs in
the previous code. Also, while I'm here, I've moved a lot of
duplicated modalfatalbox() type functions from application main
program files into wincons.c / uxcons.c, which I think saves
duplication overall. (A minor visible effect is that the prefixes on
those console-based fatal error messages will now be more consistent
between applications.)
This commit is contained in:
Simon Tatham
2018-10-11 19:58:42 +01:00
parent 109df9f46b
commit b4c8fd9d86
42 changed files with 1046 additions and 719 deletions
Download Patch File Download Diff File Expand all files Collapse all files

107
pscp.c
View File

@ -61,6 +61,29 @@ const char *const appname = "PSCP";
void ldisc_echoedit_update(Ldisc *ldisc) { }
static int pscp_output(Seat *, int is_stderr, const void *, int);
static int pscp_eof(Seat *);
static const SeatVtable pscp_seat_vt = {
pscp_output,
pscp_eof,
filexfer_get_userpass_input,
nullseat_notify_remote_exit,
console_connection_fatal,
nullseat_update_specials_menu,
nullseat_get_ttymode,
nullseat_set_busy_status,
console_verify_ssh_host_key,
console_confirm_weak_crypto_primitive,
console_confirm_weak_cached_hostkey,
nullseat_is_never_utf8,
nullseat_echoedit_update,
nullseat_get_x_display,
nullseat_get_windowid,
nullseat_get_char_cell_size,
};
static Seat pscp_seat[1] = {{ &pscp_seat_vt }};
static void tell_char(FILE *stream, char c)
{
fputc(c, stream);
@ -103,56 +126,6 @@ static void tell_user(FILE *stream, const char *fmt, ...)
sfree(str2);
}
/*
* Print an error message and perform a fatal exit.
*/
void modalfatalbox(const char *fmt, ...)
{
char *str, *str2;
va_list ap;
va_start(ap, fmt);
str = dupvprintf(fmt, ap);
str2 = dupcat("Fatal: ", str, "\n", NULL);
sfree(str);
va_end(ap);
abandon_stats();
tell_str(stderr, str2);
sfree(str2);
errs++;
cleanup_exit(1);
}
void nonfatal(const char *fmt, ...)
{
char *str, *str2;
va_list ap;
va_start(ap, fmt);
str = dupvprintf(fmt, ap);
str2 = dupcat("Error: ", str, "\n", NULL);
sfree(str);
va_end(ap);
abandon_stats();
tell_str(stderr, str2);
sfree(str2);
errs++;
}
void connection_fatal(Frontend *frontend, const char *fmt, ...)
{
char *str, *str2;
va_list ap;
va_start(ap, fmt);
str = dupvprintf(fmt, ap);
str2 = dupcat("Fatal: ", str, "\n", NULL);
sfree(str);
va_end(ap);
abandon_stats();
tell_str(stderr, str2);
sfree(str2);
errs++;
cleanup_exit(1);
}
/*
* In pscp, all agent requests should be synchronous, so this is a
* never-called stub.
@ -168,16 +141,16 @@ void agent_schedule_callback(void (*callback)(void *, void *, int),
* is available.
*
* To do this, we repeatedly call the SSH protocol module, with our
* own trap in from_backend() to catch the data that comes back. We
* do this until we have enough data.
* own pscp_output() function to catch the data that comes back. We do
* this until we have enough data.
*/
static unsigned char *outptr; /* where to put the data */
static unsigned outlen; /* how much data required */
static unsigned char *pending = NULL; /* any spare data */
static unsigned pendlen = 0, pendsize = 0; /* length and phys. size of buffer */
int from_backend(Frontend *frontend, int is_stderr,
const void *data, int datalen)
static int pscp_output(Seat *seat, int is_stderr,
const void *data, int datalen)
{
unsigned char *p = (unsigned char *) data;
unsigned len = (unsigned) datalen;
@ -215,7 +188,7 @@ int from_backend(Frontend *frontend, int is_stderr,
return 0;
}
int from_backend_eof(Frontend *frontend)
static int pscp_eof(Seat *seat)
{
/*
* We usually expect to be the party deciding when to close the
@ -224,8 +197,8 @@ int from_backend_eof(Frontend *frontend)
* downloading rather than uploading.
*/
if ((using_sftp || uploading) && !sent_eof) {
connection_fatal(frontend,
"Received unexpected end-of-file from server");
seat_connection_fatal(
pscp_seat, "Received unexpected end-of-file from server");
}
return FALSE;
}
@ -325,7 +298,7 @@ static void bump(const char *fmt, ...)
* Wait for the reply to a single SFTP request. Parallels the same
* function in psftp.c (but isn't centralised into sftp.c because the
* latter module handles SFTP only and shouldn't assume that SFTP is
* the only thing going on by calling connection_fatal).
* the only thing going on by calling seat_connection_fatal).
*/
struct sftp_packet *sftp_wait_for_reply(struct sftp_request *req)
{
@ -334,13 +307,17 @@ struct sftp_packet *sftp_wait_for_reply(struct sftp_request *req)
sftp_register(req);
pktin = sftp_recv();
if (pktin == NULL)
connection_fatal(NULL, "did not receive SFTP response packet "
"from server");
if (pktin == NULL) {
seat_connection_fatal(
pscp_seat, "did not receive SFTP response packet from server");
}
rreq = sftp_find_request(pktin);
if (rreq != req)
connection_fatal(NULL, "unable to understand SFTP response packet "
"from server: %s", fxp_error());
if (rreq != req) {
seat_connection_fatal(
pscp_seat,
"unable to understand SFTP response packet from server: %s",
fxp_error());
}
return pktin;
}
@ -513,7 +490,7 @@ static void do_cmd(char *host, char *user, char *cmd)
platform_psftp_pre_conn_setup();
err = backend_init(&ssh_backend, NULL, &backend, logctx, conf,
err = backend_init(&ssh_backend, pscp_seat, &backend, logctx, conf,
conf_get_str(conf, CONF_host),
conf_get_int(conf, CONF_port),
&realhost, 0,