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openocd/src/server/telnet_server.c

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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);
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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