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Wait for port to be configed before write / read

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Before picocom enters it's main loop and data are written to serial
port, and also before the first data are read from the port, the port
must first be configured. That is: The first data read from picocom's
standard input (or the initstring) must be written to the port, *after*
the port has been configured to the settings specified by picocom's
command-line arguments; also, the first data must be read from the port,
after the port has been configured (as any data read before, will most
likely be garbage).

When tn2217_write() is called it checks that the initial negotiations
have completed, and that the RFC2217 port-configuration commands have
been transmitted. If this is not true, then the function waits by
reading from the port and processing commands until the condition
becomes true or a timeout expires.

When tn2217_read() is called it checks that the initial negotiations
have completed, that the RFC2217 port-configuration commands have been
transmitted *AND* that their replies have been received. Any user-data
read by picocom before the replies to the commands are received will
most likely be data read by the server using the old port configuration
and therefore useless (garbage). To make the test easier, we actually
check that an equal number of replies-to-configuration-commands has been
received as configuration-commands have been sent (a misbehaving server
can confuse us by sending multiple replies to commands, but this is
always the case). Again, then the function waits by reading from the
port and processing commands until the condition becomes true or a
timeout expires.

See also discussion in issue #95
This commit is contained in:
Nick Patavalis
2018-02-24 10:15:14 +02:00
parent 6b15b80846
commit 0f2194d6a8
1 changed files with 179 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

186
tn2217.c
View File

@ -34,6 +34,7 @@
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netdb.h>
#include <errno.h>
@ -102,19 +103,21 @@ struct tn2217_state {
unsigned char cmdbuflen;
unsigned int cmdiac : 1; /* 1 iff last cmdbuf ch is incomplete IAC */
int conf_pending; /* # of not-replied config commands */
/* When COM-PORT option is fully negotiated, can_comport
* is set to true. This also means that any deferred termios/modem
* settings will be triggered. */
unsigned int can_comport : 1, /* WILL COMPORT was received */
set_termios : 1, /* tcsetattr called before can_comport */
set_modem : 1; /* modem_bis/c called before can_comport */
set_modem : 1, /* modem_bis/c called before can_comport */
configed: 1; /* INITIAL config complete */
};
static int tn2217_remote_should(struct term_s *t, unsigned char opt);
static int tn2217_local_should(struct term_s *t, unsigned char opt);
static int tn2217_write(struct term_s *t, const void *buf, unsigned bufsz);
static int escape_write(struct term_s *t, const void *buf, unsigned bufsz);
static void tn2217_recv_comport_cmd(struct term_s *t, unsigned char cmd,
unsigned char *data, unsigned int datalen);
static void tn2217_comport_start(struct term_s *t);
@ -293,7 +296,7 @@ tn2217_recv_opt(struct term_s *t, unsigned char op, unsigned char opt)
/* Receive and process a single byte of an IAC command.
* The caller will have appended the byte to s->cmdbuf[] already.
* Completion of a command is signaled by setting s->cmdbuflen to 0. */
static void
static int
tn2217_recv_cmd_partial(struct term_s *t)
{
struct tn2217_state *s = STATE(t);
@ -347,8 +350,9 @@ tn2217_recv_cmd_partial(struct term_s *t)
break;
}
s->cmdbuflen = 0;
return 1;
incomplete:
return;
return 0;
}
/* Should the remote enable its option if it tells us it WILL/WONT? */
@ -440,7 +444,7 @@ tn2217_send_comport_cmd(struct term_s *t, unsigned char cmd,
/* assert(cmd != IAC); */
writen_ni(t->fd, msg, sizeof msg);
if (datalen)
tn2217_write(t, data, datalen);
escape_write(t, data, datalen);
writen_ni(t->fd, end, sizeof end);
}
@ -513,14 +517,19 @@ modem_repr(int m)
static void
tn2217_send_set_baudrate(struct term_s *t, int speed)
{
if (speed >= 0)
struct tn2217_state *s = STATE(t);
if (speed >= 0) {
tn2217_send_comport_cmd4(t, COMPORT_SET_BAUDRATE, speed);
s->conf_pending++;
}
}
/* Sends a SET-DATASIZE message to the remote */
static void
tn2217_send_set_datasize(struct term_s *t, int databits)
{
struct tn2217_state *s = STATE(t);
unsigned char val;
switch (databits) {
@ -530,12 +539,14 @@ tn2217_send_set_datasize(struct term_s *t, int databits)
default: val = COMPORT_DATASIZE_8; break;
}
tn2217_send_comport_cmd1(t, COMPORT_SET_DATASIZE, val);
s->conf_pending++;
}
/* Sends a SET-PARITY message to the remote */
static void
tn2217_send_set_parity(struct term_s *t, enum parity_e parity)
{
struct tn2217_state *s = STATE(t);
unsigned char val;
switch (parity) {
@ -544,22 +555,27 @@ tn2217_send_set_parity(struct term_s *t, enum parity_e parity)
default: val = COMPORT_PARITY_NONE; break;
}
tn2217_send_comport_cmd1(t, COMPORT_SET_PARITY, val);
s->conf_pending++;
}
/* Sends a SET-STOPSIZE message to the remote */
static void
tn2217_send_set_stopsize(struct term_s *t, int stopbits)
{
struct tn2217_state *s = STATE(t);
if (stopbits == 2)
tn2217_send_comport_cmd1(t, COMPORT_SET_STOPSIZE, COMPORT_STOPSIZE_2);
else
tn2217_send_comport_cmd1(t, COMPORT_SET_STOPSIZE, COMPORT_STOPSIZE_1);
s->conf_pending++;
}
/* Sends a SET-CONTROL message to control hardware flow control */
static void
tn2217_send_set_fc(struct term_s *t, enum flowcntrl_e flow)
{
struct tn2217_state *s = STATE(t);
unsigned char val;
switch (flow) {
@ -575,6 +591,7 @@ tn2217_send_set_fc(struct term_s *t, enum flowcntrl_e flow)
break;
}
tn2217_send_comport_cmd1(t, COMPORT_SET_CONTROL, val);
s->conf_pending++;
}
/* Sends a SET-CONTROL message to control remote DTR state */
@ -638,6 +655,7 @@ tn2217_comport_start(struct term_s *t)
COMPORT_STOPSIZE_REQUEST);
tn2217_send_comport_cmd1(t, COMPORT_SET_CONTROL,
COMPORT_CONTROL_FC_REQUEST);
s->conf_pending += 5;
}
if (s->set_modem) {
@ -691,6 +709,7 @@ tn2217_recv_comport_cmd(struct term_s *t, unsigned char cmd,
}
/* XXX the sredird server sends an extra 4-byte value,
* which looks like the ispeed. It is not in the RFC. */
s->conf_pending--;
break;
case COMPORT_SET_DATASIZE: /* Notification of remote data bit size */
@ -705,6 +724,7 @@ tn2217_recv_comport_cmd(struct term_s *t, unsigned char cmd,
tios_set_databits(tio, val);
DEBUG("[notified: DATASIZE: %d]\r\n", val);
}
s->conf_pending--;
break;
case COMPORT_SET_PARITY: /* Remote parity update */
@ -719,6 +739,7 @@ tn2217_recv_comport_cmd(struct term_s *t, unsigned char cmd,
DEBUG("[notified: PARITY: %s]\r\n", parity_str[val]);
}
s->conf_pending--;
break;
case COMPORT_SET_STOPSIZE: /* Remote stop bits update */
@ -731,6 +752,7 @@ tn2217_recv_comport_cmd(struct term_s *t, unsigned char cmd,
tios_set_stopbits(tio, val);
DEBUG("[notified: STOPSIZE: %d]\r\n", val);
}
s->conf_pending--;
break;
case COMPORT_SET_CONTROL: /* Remote control state update */
@ -741,11 +763,13 @@ tn2217_recv_comport_cmd(struct term_s *t, unsigned char cmd,
tios_set_flowcntrl(tio, FC_XONXOFF);
DEBUG("[notified: SET_CONTROL: %d: FLOW: %s]\r\n",
data[0], parity_str[FC_XONXOFF]);
s->conf_pending--;
break;
case COMPORT_CONTROL_FC_HARDWARE:
tios_set_flowcntrl(tio, FC_RTSCTS);
DEBUG("[notified: SET_CONTROL: %d: FLOW: %s]\r\n",
data[0], parity_str[FC_RTSCTS]);
s->conf_pending--;
break;
case COMPORT_CONTROL_FC_NONE:
case COMPORT_CONTROL_FC_DCD:
@ -753,6 +777,7 @@ tn2217_recv_comport_cmd(struct term_s *t, unsigned char cmd,
tios_set_flowcntrl(tio, FC_NONE);
DEBUG("[notified: SET_CONTROL: %d: FLOW: %s]\r\n",
data[0], parity_str[FC_NONE]);
s->conf_pending--;
break;
/* DTR changes and COMPORT_CONTROL_DTR_REQUEST reply */
case COMPORT_CONTROL_DTR_ON:
@ -942,6 +967,114 @@ tn2217_drain(struct term_s *t)
return 0;
}
/* Wait (keep reading from fd) for a command to be received and
processed, or for timeout to expire. Returns a positive if a
command was received and processed or if the timeout expired,
returns zero if read(2) returns zero, and returns a negative on
error. User-data read while waiting are discarded. */
static int
tn2217_wait_cmd(struct term_s *t, struct timeval *tmo_tv)
{
struct tn2217_state *s = STATE(t);
unsigned char c;
int r, cmd = 0;
fd_set rdset;
do {
FD_ZERO(&rdset);
FD_SET(t->fd, &rdset);
r = select(t->fd + 1, &rdset, 0, 0, tmo_tv);
if ( r <= 0 )
return r == 0 ? 1 : -1;
r = read(t->fd, &c, 1);
if ( r <= 0 )
return r;
if ( s->cmdbuflen ) {
if (s->cmdbuflen >= sizeof s->cmdbuf -1) {
s->cmdbuflen = 0; /* Abandon on overflow */
fprintf(stderr, "[overlong IAC command]\r\n");
continue;
}
s->cmdbuf[s->cmdbuflen++] = c;
if ( s->cmdbuflen == 2 && s->cmdbuf[1] == IAC )
s->cmdbuflen = 0;
else
cmd = tn2217_recv_cmd_partial(t);
} else {
if ( c == IAC ) {
s->cmdbuf[0] = IAC;
s->cmdbuflen = 1;
}
}
} while ( ! cmd );
return 1;
}
/* Condition: Initial configuration completed. That is: initial
negotiations completed, configuration commands sent, *and*
replies received. To be used with tn2217_wait_cond(). */
static int cond_initial_conf_complete(struct term_s *t)
{
struct tn2217_state *s = STATE(t);
int v;
v = s->configed || ( s->can_comport && ! s->conf_pending );
if ( v )
s->configed = 1;
return v;
}
/* Condition: Initial negotiations completed, and configuration
commands sent, but replies not yet received. To be used with
tn2217_wait_cond(). */
static int cond_comport_start(struct term_s *t)
{
return STATE(t)->can_comport;
}
static struct timeval *
msec2tv (struct timeval *tv, long ms)
{
tv->tv_sec = ms / 1000;
tv->tv_usec = (ms % 1000) * 1000;
return tv;
}
/* Wait (keep reading from the fd and processing commands) until the
condition is satisfied (that is, until "cond" returns non-zero), or
until the timeout expires. Returns a positive on success, zero if
read(2) returned zero, and a negative on any other error
(incl. timeoute expiration). On timeout expiration, errno is set to
ETIME.*/
static int
tn2217_wait_cond(struct term_s *t, int (*cond)(struct term_s *t), int tmo_msec)
{
struct timeval now, tmo_tv, tmo_abs;
int r;
msec2tv(&tmo_tv, tmo_msec);
gettimeofday(&now, 0);
timeradd(&now, &tmo_tv, &tmo_abs);
while ( ! cond(t) ) {
r = tn2217_wait_cmd(t, &tmo_tv);
if ( r <= 0 )
return r;
gettimeofday(&now, 0);
if ( timercmp(&now, &tmo_abs, <) ) {
timersub(&tmo_abs, &now, &tmo_tv);
} else {
errno = ETIME;
return -1;
}
}
return 1;
}
/* Reads raw binary from the socket and immediately handles any
* in-stream TELNET commands. */
static int
@ -951,6 +1084,20 @@ tn2217_read(struct term_s *t, void *buf, unsigned bufsz)
unsigned char *in, *out;
int inlen, outlen;
unsigned char *iac;
int r;
/* FIXME(npat): Maybe don't wait if s->set_termios is not set
(--noinit) */
if ( ! cond_initial_conf_complete(t) ) {
/* Port may not have been configured yet. Wait for
negotiations to end, and configuration commands to get
transmitted *and* replies received. */
DEBUG("tn2217_read WAITING initial_conf_complete\r\n");
r = tn2217_wait_cond(t, cond_initial_conf_complete, 5000);
if ( r <= 0 )
return r;
DEBUG("tn2217_read GOT initial_conf_complete\r\n");
}
inlen = read(t->fd, buf, bufsz);
if (inlen <= 0)
@ -1019,7 +1166,7 @@ tn2217_read(struct term_s *t, void *buf, unsigned bufsz)
}
static int
tn2217_write(struct term_s *t, const void *buf, unsigned bufsz)
escape_write(struct term_s *t, const void *buf, unsigned bufsz)
{
const unsigned char *start, *end;
unsigned int len;
@ -1042,6 +1189,31 @@ tn2217_write(struct term_s *t, const void *buf, unsigned bufsz)
return bufsz;
}
static int
tn2217_write(struct term_s *t, const void *buf, unsigned bufsz)
{
int r;
/* FIXME(npat): Maybe don't wait if s->set_termios is not set
(--noinit) */
if ( ! cond_comport_start(t) ) {
/* Port may not have been configured yet. Wait for
negotiations to end, and configuration commands to get
transmitted. It is not necessary to wait for them to get
replied. */
DEBUG("tn2217_write WAITING comport_start\r\n");
r = tn2217_wait_cond(t, cond_comport_start, 5000);
if ( r <= 0 ) {
if ( r == 0 ) errno = EPIPE;
return -1;
}
DEBUG("tn2217_write GOT comport_start\r\n");
}
return escape_write(t, buf, bufsz);
}
const struct term_ops tn2217_ops = {
.init = tn2217_init,
.fini = tn2217_fini,