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openocd/src/server/telnet_server.c
Tarek BOCHKATI 7e6556b3ca server: permit the add_service function to return the created service 
returning the created service seems useful:

as the only method to get the freshly created service is by getting the
last item in the services linked list, and this seems to be like an
intrusion to service internal mechanism.

possibly, we could get the service from a connection but this is possible
only from [new_connection|input|connection_closed]_handler_t, but this is
not always practical:
  example: armv7m: add a TCP channel to stream captured trace
           http://openocd.zylin.com/#/c/5345/
           here we poll for trace and broadcast to all connections
           outside of these xxx_handler_t functions

also, storing one of the connections in new_connection_handler_t and get
the service from it is possible, but this will make the code less readable.

Change-Id: I5fef1baecec1e054953c6faf5b99d864ecc97f02
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: http://openocd.zylin.com/5717
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins
2020-11-07 20:49:53 +00:00

748 lines
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/***************************************************************************
* Copyright (C) 2005 by Dominic Rath *
* Dominic.Rath@gmx.de *
* *
* Copyright (C) 2007-2010 Øyvind Harboe *
* oyvind.harboe@zylin.com *
* *
* Copyright (C) 2008 by Spencer Oliver *
* spen@spen-soft.co.uk *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/>. *
***************************************************************************/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "telnet_server.h"
#include <target/target_request.h>
#include <helper/configuration.h>
static char *telnet_port;
static char *negotiate =
"\xFF\xFB\x03" /* IAC WILL Suppress Go Ahead */
"\xFF\xFB\x01" /* IAC WILL Echo */
"\xFF\xFD\x03" /* IAC DO Suppress Go Ahead */
"\xFF\xFE\x01"; /* IAC DON'T Echo */
#define CTRL(c) (c - '@')
#define TELNET_HISTORY ".openocd_history"
/* The only way we can detect that the socket is closed is the first time
* we write to it, we will fail. Subsequent write operations will
* succeed. Shudder!
*/
static int telnet_write(struct connection *connection, const void *data,
int len)
{
struct telnet_connection *t_con = connection->priv;
if (t_con->closed)
return ERROR_SERVER_REMOTE_CLOSED;
if (connection_write(connection, data, len) == len)
return ERROR_OK;
t_con->closed = true;
return ERROR_SERVER_REMOTE_CLOSED;
}
static int telnet_prompt(struct connection *connection)
{
struct telnet_connection *t_con = connection->priv;
return telnet_write(connection, t_con->prompt, strlen(t_con->prompt));
}
static int telnet_outputline(struct connection *connection, const char *line)
{
int len;
/* process lines in buffer */
while (*line) {
char *line_end = strchr(line, '\n');
if (line_end)
len = line_end-line;
else
len = strlen(line);
telnet_write(connection, line, len);
if (line_end) {
telnet_write(connection, "\r\n", 2);
line += len + 1;
} else
line += len;
}
return ERROR_OK;
}
static int telnet_output(struct command_context *cmd_ctx, const char *line)
{
struct connection *connection = cmd_ctx->output_handler_priv;
return telnet_outputline(connection, line);
}
static void telnet_log_callback(void *priv, const char *file, unsigned line,
const char *function, const char *string)
{
struct connection *connection = priv;
struct telnet_connection *t_con = connection->priv;
size_t i;
size_t tmp;
/* If the prompt is not visible, simply output the message. */
if (!t_con->prompt_visible) {
telnet_outputline(connection, string);
return;
}
/* Clear the command line. */
tmp = strlen(t_con->prompt) + t_con->line_size;
for (i = 0; i < tmp; i += 16)
telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
MIN(tmp - i, 16));
for (i = 0; i < tmp; i += 16)
telnet_write(connection, " ", MIN(tmp - i, 16));
for (i = 0; i < tmp; i += 16)
telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
MIN(tmp - i, 16));
telnet_outputline(connection, string);
/* Put the command line to its previous state. */
telnet_prompt(connection);
telnet_write(connection, t_con->line, t_con->line_size);
for (i = t_con->line_cursor; i < t_con->line_size; i++)
telnet_write(connection, "\b", 1);
}
static void telnet_load_history(struct telnet_connection *t_con)
{
FILE *histfp;
char buffer[TELNET_BUFFER_SIZE];
int i = 0;
char *history = get_home_dir(TELNET_HISTORY);
if (history == NULL) {
LOG_INFO("unable to get user home directory, telnet history will be disabled");
return;
}
histfp = fopen(history, "rb");
if (histfp) {
while (fgets(buffer, sizeof(buffer), histfp) != NULL) {
char *p = strchr(buffer, '\n');
if (p)
*p = '\0';
if (buffer[0] && i < TELNET_LINE_HISTORY_SIZE)
t_con->history[i++] = strdup(buffer);
}
t_con->next_history = i;
t_con->next_history %= TELNET_LINE_HISTORY_SIZE;
/* try to set to last entry - 1, that way we skip over any exit/shutdown cmds */
t_con->current_history = t_con->next_history > 0 ? i - 1 : 0;
fclose(histfp);
}
free(history);
}
static void telnet_save_history(struct telnet_connection *t_con)
{
FILE *histfp;
int i;
int num;
char *history = get_home_dir(TELNET_HISTORY);
if (history == NULL) {
LOG_INFO("unable to get user home directory, telnet history will be disabled");
return;
}
histfp = fopen(history, "wb");
if (histfp) {
num = TELNET_LINE_HISTORY_SIZE;
i = t_con->current_history + 1;
i %= TELNET_LINE_HISTORY_SIZE;
while (t_con->history[i] == NULL && num > 0) {
i++;
i %= TELNET_LINE_HISTORY_SIZE;
num--;
}
if (num > 0) {
for (; num > 0; num--) {
fprintf(histfp, "%s\n", t_con->history[i]);
i++;
i %= TELNET_LINE_HISTORY_SIZE;
}
}
fclose(histfp);
}
free(history);
}
static int telnet_new_connection(struct connection *connection)
{
struct telnet_connection *telnet_connection;
struct telnet_service *telnet_service = connection->service->priv;
int i;
telnet_connection = malloc(sizeof(struct telnet_connection));
if (!telnet_connection) {
LOG_ERROR("Failed to allocate telnet connection.");
return ERROR_FAIL;
}
connection->priv = telnet_connection;
/* initialize telnet connection information */
telnet_connection->closed = false;
telnet_connection->line_size = 0;
telnet_connection->line_cursor = 0;
telnet_connection->prompt = strdup("> ");
telnet_connection->prompt_visible = true;
telnet_connection->state = TELNET_STATE_DATA;
/* output goes through telnet connection */
command_set_output_handler(connection->cmd_ctx, telnet_output, connection);
/* negotiate telnet options */
telnet_write(connection, negotiate, strlen(negotiate));
/* print connection banner */
if (telnet_service->banner) {
telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
telnet_write(connection, "\r\n", 2);
}
/* the prompt is always placed at the line beginning */
telnet_write(connection, "\r", 1);
telnet_prompt(connection);
/* initialize history */
for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
telnet_connection->history[i] = NULL;
telnet_connection->next_history = 0;
telnet_connection->current_history = 0;
telnet_load_history(telnet_connection);
log_add_callback(telnet_log_callback, connection);
return ERROR_OK;
}
static void telnet_clear_line(struct connection *connection,
struct telnet_connection *t_con)
{
/* move to end of line */
if (t_con->line_cursor < t_con->line_size)
telnet_write(connection,
t_con->line + t_con->line_cursor,
t_con->line_size - t_con->line_cursor);
/* backspace, overwrite with space, backspace */
while (t_con->line_size > 0) {
telnet_write(connection, "\b \b", 3);
t_con->line_size--;
}
t_con->line_cursor = 0;
}
static void telnet_history_go(struct connection *connection, int idx)
{
struct telnet_connection *t_con = connection->priv;
if (t_con->history[idx]) {
telnet_clear_line(connection, t_con);
t_con->line_size = strlen(t_con->history[idx]);
t_con->line_cursor = t_con->line_size;
memcpy(t_con->line, t_con->history[idx], t_con->line_size);
telnet_write(connection, t_con->line, t_con->line_size);
t_con->current_history = idx;
}
t_con->state = TELNET_STATE_DATA;
}
static void telnet_history_up(struct connection *connection)
{
struct telnet_connection *t_con = connection->priv;
size_t last_history = (t_con->current_history > 0) ?
t_con->current_history - 1 :
TELNET_LINE_HISTORY_SIZE-1;
telnet_history_go(connection, last_history);
}
static void telnet_history_down(struct connection *connection)
{
struct telnet_connection *t_con = connection->priv;
size_t next_history;
next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
telnet_history_go(connection, next_history);
}
static int telnet_history_print(struct connection *connection)
{
struct telnet_connection *tc;
tc = connection->priv;
for (size_t i = 1; i < TELNET_LINE_HISTORY_SIZE; i++) {
char *line;
/*
* The tc->next_history line contains empty string (unless NULL), thus
* it is not printed.
*/
line = tc->history[(tc->next_history + i) % TELNET_LINE_HISTORY_SIZE];
if (line) {
telnet_write(connection, line, strlen(line));
telnet_write(connection, "\r\n\x00", 3);
}
}
tc->line_size = 0;
tc->line_cursor = 0;
/* The prompt is always placed at the line beginning. */
telnet_write(connection, "\r", 1);
return telnet_prompt(connection);
}
static void telnet_move_cursor(struct connection *connection, size_t pos)
{
struct telnet_connection *tc;
size_t tmp;
tc = connection->priv;
if (pos < tc->line_cursor) {
tmp = tc->line_cursor - pos;
for (size_t i = 0; i < tmp; i += 16)
telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b",
MIN(tmp - i, 16));
} else {
tmp = pos - tc->line_cursor;
for (size_t i = 0; i < tmp; i += 16)
telnet_write(connection, tc->line + tc->line_cursor + i,
MIN(tmp - i, 16));
}
tc->line_cursor = pos;
}
static int telnet_input(struct connection *connection)
{
int bytes_read;
unsigned char buffer[TELNET_BUFFER_SIZE];
unsigned char *buf_p;
struct telnet_connection *t_con = connection->priv;
struct command_context *command_context = connection->cmd_ctx;
bytes_read = connection_read(connection, buffer, TELNET_BUFFER_SIZE);
if (bytes_read == 0)
return ERROR_SERVER_REMOTE_CLOSED;
else if (bytes_read == -1) {
LOG_ERROR("error during read: %s", strerror(errno));
return ERROR_SERVER_REMOTE_CLOSED;
}
buf_p = buffer;
while (bytes_read) {
switch (t_con->state) {
case TELNET_STATE_DATA:
if (*buf_p == 0xff)
t_con->state = TELNET_STATE_IAC;
else {
if (isprint(*buf_p)) { /* printable character */
/* watch buffer size leaving one spare character for
* string null termination */
if (t_con->line_size == TELNET_LINE_MAX_SIZE-1) {
/* output audible bell if buffer is full
* "\a" does not work, at least on windows */
telnet_write(connection, "\x07", 1);
} else if (t_con->line_cursor == t_con->line_size) {
telnet_write(connection, buf_p, 1);
t_con->line[t_con->line_size++] = *buf_p;
t_con->line_cursor++;
} else {
size_t i;
memmove(t_con->line + t_con->line_cursor + 1,
t_con->line + t_con->line_cursor,
t_con->line_size - t_con->line_cursor);
t_con->line[t_con->line_cursor] = *buf_p;
t_con->line_size++;
telnet_write(connection,
t_con->line + t_con->line_cursor,
t_con->line_size - t_con->line_cursor);
t_con->line_cursor++;
for (i = t_con->line_cursor; i < t_con->line_size; i++)
telnet_write(connection, "\b", 1);
}
} else { /* non-printable */
if (*buf_p == 0x1b) { /* escape */
t_con->state = TELNET_STATE_ESCAPE;
t_con->last_escape = '\x00';
} else if ((*buf_p == 0xd) || (*buf_p == 0xa)) { /* CR/LF */
int retval;
/* skip over combinations with CR/LF and NUL characters */
if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) ||
(*(buf_p + 1) == 0xd))) {
buf_p++;
bytes_read--;
}
if ((bytes_read > 1) && (*(buf_p + 1) == 0)) {
buf_p++;
bytes_read--;
}
t_con->line[t_con->line_size] = 0;
telnet_write(connection, "\r\n\x00", 3);
if (strcmp(t_con->line, "history") == 0) {
retval = telnet_history_print(connection);
if (retval != ERROR_OK)
return retval;
continue;
}
/* save only non-blank not repeating lines in the history */
char *prev_line = t_con->history[(t_con->current_history > 0) ?
t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1];
if (*t_con->line && (prev_line == NULL ||
strcmp(t_con->line, prev_line))) {
/* if the history slot is already taken, free it */
free(t_con->history[t_con->next_history]);
/* add line to history */
t_con->history[t_con->next_history] = strdup(t_con->line);
/* wrap history at TELNET_LINE_HISTORY_SIZE */
t_con->next_history = (t_con->next_history + 1) %
TELNET_LINE_HISTORY_SIZE;
/* current history line starts at the new entry */
t_con->current_history =
t_con->next_history;
free(t_con->history[t_con->current_history]);
t_con->history[t_con->current_history] = strdup("");
}
t_con->line_size = 0;
/* to suppress prompt in log callback during command execution */
t_con->prompt_visible = false;
if (strcmp(t_con->line, "shutdown") == 0)
telnet_save_history(t_con);
retval = command_run_line(command_context, t_con->line);
t_con->line_cursor = 0;
t_con->prompt_visible = true;
if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
return ERROR_SERVER_REMOTE_CLOSED;
/* the prompt is always * placed at the line beginning */
telnet_write(connection, "\r", 1);
retval = telnet_prompt(connection);
if (retval == ERROR_SERVER_REMOTE_CLOSED)
return ERROR_SERVER_REMOTE_CLOSED;
} else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) { /* delete character */
if (t_con->line_cursor > 0) {
if (t_con->line_cursor != t_con->line_size) {
size_t i;
telnet_write(connection, "\b", 1);
t_con->line_cursor--;
t_con->line_size--;
memmove(t_con->line + t_con->line_cursor,
t_con->line + t_con->line_cursor + 1,
t_con->line_size -
t_con->line_cursor);
telnet_write(connection,
t_con->line + t_con->line_cursor,
t_con->line_size -
t_con->line_cursor);
telnet_write(connection, " \b", 2);
for (i = t_con->line_cursor; i < t_con->line_size; i++)
telnet_write(connection, "\b", 1);
} else {
t_con->line_size--;
t_con->line_cursor--;
/* back space: move the 'printer' head one char
* back, overwrite with space, move back again */
telnet_write(connection, "\b \b", 3);
}
}
} else if (*buf_p == 0x15) /* clear line */
telnet_clear_line(connection, t_con);
else if (*buf_p == CTRL('B')) { /* cursor left */
if (t_con->line_cursor > 0) {
telnet_write(connection, "\b", 1);
t_con->line_cursor--;
}
t_con->state = TELNET_STATE_DATA;
} else if (*buf_p == CTRL('F')) { /* cursor right */
if (t_con->line_cursor < t_con->line_size)
telnet_write(connection, t_con->line + t_con->line_cursor++, 1);
t_con->state = TELNET_STATE_DATA;
} else if (*buf_p == CTRL('P')) /* cursor up */
telnet_history_up(connection);
else if (*buf_p == CTRL('N')) /* cursor down */
telnet_history_down(connection);
else if (*buf_p == CTRL('A'))
telnet_move_cursor(connection, 0);
else if (*buf_p == CTRL('E'))
telnet_move_cursor(connection, t_con->line_size);
else if (*buf_p == CTRL('K')) { /* kill line to end */
if (t_con->line_cursor < t_con->line_size) {
/* overwrite with space, until end of line, move back */
for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
telnet_write(connection, " ", 1);
for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
telnet_write(connection, "\b", 1);
t_con->line[t_con->line_cursor] = '\0';
t_con->line_size = t_con->line_cursor;
}
} else
LOG_DEBUG("unhandled nonprintable: %2.2x", *buf_p);
}
}
break;
case TELNET_STATE_IAC:
switch (*buf_p) {
case 0xfe:
t_con->state = TELNET_STATE_DONT;
break;
case 0xfd:
t_con->state = TELNET_STATE_DO;
break;
case 0xfc:
t_con->state = TELNET_STATE_WONT;
break;
case 0xfb:
t_con->state = TELNET_STATE_WILL;
break;
}
break;
case TELNET_STATE_SB:
break;
case TELNET_STATE_SE:
break;
case TELNET_STATE_WILL:
case TELNET_STATE_WONT:
case TELNET_STATE_DO:
case TELNET_STATE_DONT:
t_con->state = TELNET_STATE_DATA;
break;
case TELNET_STATE_ESCAPE:
if (t_con->last_escape == '[') {
if (*buf_p == 'D') { /* cursor left */
if (t_con->line_cursor > 0) {
telnet_write(connection, "\b", 1);
t_con->line_cursor--;
}
t_con->state = TELNET_STATE_DATA;
} else if (*buf_p == 'C') { /* cursor right */
if (t_con->line_cursor < t_con->line_size)
telnet_write(connection,
t_con->line + t_con->line_cursor++, 1);
t_con->state = TELNET_STATE_DATA;
} else if (*buf_p == 'A') { /* cursor up */
telnet_history_up(connection);
} else if (*buf_p == 'B') { /* cursor down */
telnet_history_down(connection);
} else if (*buf_p == '3')
t_con->last_escape = *buf_p;
else
t_con->state = TELNET_STATE_DATA;
} else if (t_con->last_escape == '3') {
/* Remove character */
if (*buf_p == '~') {
if (t_con->line_cursor < t_con->line_size) {
size_t i;
t_con->line_size--;
/* remove char from line buffer */
memmove(t_con->line + t_con->line_cursor,
t_con->line + t_con->line_cursor + 1,
t_con->line_size - t_con->line_cursor);
/* print remainder of buffer */
telnet_write(connection, t_con->line + t_con->line_cursor,
t_con->line_size - t_con->line_cursor);
/* overwrite last char with whitespace */
telnet_write(connection, " \b", 2);
/* move back to cursor position*/
for (i = t_con->line_cursor; i < t_con->line_size; i++)
telnet_write(connection, "\b", 1);
}
t_con->state = TELNET_STATE_DATA;
} else
t_con->state = TELNET_STATE_DATA;
} else if (t_con->last_escape == '\x00') {
if (*buf_p == '[')
t_con->last_escape = *buf_p;
else
t_con->state = TELNET_STATE_DATA;
} else {
LOG_ERROR("BUG: unexpected value in t_con->last_escape");
t_con->state = TELNET_STATE_DATA;
}
break;
default:
LOG_ERROR("unknown telnet state");
return ERROR_FAIL;
}
bytes_read--;
buf_p++;
}
return ERROR_OK;
}
static int telnet_connection_closed(struct connection *connection)
{
struct telnet_connection *t_con = connection->priv;
int i;
log_remove_callback(telnet_log_callback, connection);
free(t_con->prompt);
t_con->prompt = NULL;
/* save telnet history */
telnet_save_history(t_con);
for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++) {
free(t_con->history[i]);
t_con->history[i] = NULL;
}
/* if this connection registered a debug-message receiver delete it */
delete_debug_msg_receiver(connection->cmd_ctx, NULL);
free(connection->priv);
connection->priv = NULL;
return ERROR_OK;
}
int telnet_init(char *banner)
{
if (strcmp(telnet_port, "disabled") == 0) {
LOG_INFO("telnet server disabled");
return ERROR_OK;
}
struct telnet_service *telnet_service =
malloc(sizeof(struct telnet_service));
if (!telnet_service) {
LOG_ERROR("Failed to allocate telnet service.");
return ERROR_FAIL;
}
telnet_service->banner = banner;
int ret = add_service("telnet", telnet_port, CONNECTION_LIMIT_UNLIMITED,
telnet_new_connection, telnet_input, telnet_connection_closed,
telnet_service, NULL);
if (ret != ERROR_OK) {
free(telnet_service);
return ret;
}
return ERROR_OK;
}
/* daemon configuration command telnet_port */
COMMAND_HANDLER(handle_telnet_port_command)
{
return CALL_COMMAND_HANDLER(server_pipe_command, &telnet_port);
}
COMMAND_HANDLER(handle_exit_command)
{
return ERROR_COMMAND_CLOSE_CONNECTION;
}
static const struct command_registration telnet_command_handlers[] = {
{
.name = "exit",
.handler = handle_exit_command,
.mode = COMMAND_EXEC,
.usage = "",
.help = "exit telnet session",
},
{
.name = "telnet_port",
.handler = handle_telnet_port_command,
.mode = COMMAND_CONFIG,
.help = "Specify port on which to listen "
"for incoming telnet connections. "
"Read help on 'gdb_port'.",
.usage = "[port_num]",
},
COMMAND_REGISTRATION_DONE
};
int telnet_register_commands(struct command_context *cmd_ctx)
{
telnet_port = strdup("4444");
return register_commands(cmd_ctx, NULL, telnet_command_handlers);
}
void telnet_service_free(void)
{
free(telnet_port);
}
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