openocd: fix SPDX tag format for files .c
[fw/openocd] / src / server / telnet_server.c
index ee8d3b16a9841f7dbbcf85f3493005913aac4452..938bc5b0624972e52cf207326fbac5d6a82a85ae 100644 (file)
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
 /***************************************************************************
  *   Copyright (C) 2005 by Dominic Rath                                    *
  *   Dominic.Rath@gmx.de                                                   *
@@ -7,58 +9,52 @@
  *                                                                         *
  *   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, write to the                         *
- *   Free Software Foundation, Inc.,                                       *
- *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  ***************************************************************************/
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 
 #include "telnet_server.h"
 #include <target/target_request.h>
+#include <helper/configuration.h>
+#include <helper/list.h>
 
-static unsigned short telnet_port = 4444;
+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 */
+       "\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)
+       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 = 1;
+       t_con->closed = true;
        return ERROR_SERVER_REMOTE_CLOSED;
 }
 
+/* output an audible bell */
+static int telnet_bell(struct connection *connection)
+{
+       /* ("\a" does not work, at least on windows) */
+       return telnet_write(connection, "\x07", 1);
+}
+
 static int telnet_prompt(struct connection *connection)
 {
        struct telnet_connection *t_con = connection->priv;
@@ -80,21 +76,17 @@ static int telnet_outputline(struct connection *connection, const char *line)
                        len = strlen(line);
 
                telnet_write(connection, line, len);
-               if (line_end)
-               {
+               if (line_end) {
                        telnet_write(connection, "\r\n", 2);
                        line += len + 1;
-               }
-               else
-               {
+               } else
                        line += len;
-               }
        }
 
        return ERROR_OK;
 }
 
-static int telnet_output(struct command_context *cmd_ctx, const charline)
+static int telnet_output(struct command_context *cmd_ctx, const char *line)
 {
        struct connection *connection = cmd_ctx->output_handler_priv;
 
@@ -102,51 +94,136 @@ static int telnet_output(struct command_context *cmd_ctx, const char* line)
 }
 
 static void telnet_log_callback(void *priv, const char *file, unsigned line,
-               const char *function, const char *string)
+       const char *function, const char *string)
 {
        struct connection *connection = priv;
        struct telnet_connection *t_con = connection->priv;
-       int i;
+       size_t i;
+       size_t tmp;
 
-       /* if there is no prompt, simply output the message */
-       if (t_con->line_cursor < 0)
-       {
+       /* If the prompt is not visible, simply output the message. */
+       if (!t_con->prompt_visible) {
                telnet_outputline(connection, string);
                return;
        }
 
-       /* clear the command line */
-       for (i = strlen(t_con->prompt) + t_con->line_size; i > 0; i -= 16)
-               telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b", i > 16 ? 16 : i);
-       for (i = strlen(t_con->prompt) + t_con->line_size; i > 0; i -= 16)
-               telnet_write(connection, "                ", i > 16 ? 16 : i);
-       for (i = strlen(t_con->prompt) + t_con->line_size; i > 0; i -= 16)
-               telnet_write(connection, "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b", i > 16 ? 16 : i);
+       /* 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));
 
-       /* output the message */
        telnet_outputline(connection, string);
 
-       /* put the command line to its previous state */
+       /* 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_size; i > t_con->line_cursor; i--)
+
+       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) {
+               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)) {
+
+                       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) {
+               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] && 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 = malloc(sizeof(struct telnet_connection));
+       struct telnet_connection *telnet_connection;
        struct telnet_service *telnet_service = connection->service->priv;
-       int i;
+
+       telnet_connection = calloc(1, 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 = 0;
-       telnet_connection->line_size = 0;
-       telnet_connection->line_cursor = 0;
-       telnet_connection->option_size = 0;
        telnet_connection->prompt = strdup("> ");
+       telnet_connection->prompt_visible = true;
        telnet_connection->state = TELNET_STATE_DATA;
 
        /* output goes through telnet connection */
@@ -156,22 +233,16 @@ static int telnet_new_connection(struct connection *connection)
        telnet_write(connection, negotiate, strlen(negotiate));
 
        /* print connection banner */
-       if (telnet_service->banner)
-       {
+       if (telnet_service->banner) {
                telnet_write(connection, telnet_service->banner, strlen(telnet_service->banner));
                telnet_write(connection, "\r\n", 2);
        }
 
-       telnet_write(connection, "\r", 1); /* the prompt is always placed at the line beginning */
+       /* 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);
 
@@ -179,239 +250,594 @@ static int telnet_new_connection(struct connection *connection)
 }
 
 static void telnet_clear_line(struct connection *connection,
-               struct telnet_connection *t_con)
+       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);
-       }
+               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)
-       {
+       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 void telnet_history_add(struct connection *connection)
+{
+       struct telnet_connection *t_con = connection->priv;
+
+       /* 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 || 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("");
+       }
+}
+
+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 = connection->priv;
+       size_t tmp;
+
+       if (pos == tc->line_cursor) /* nothing to do */
+               return;
+
+       if (pos > tc->line_size) /* out of bounds */
+               return;
+
+       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;
+}
+
+/* check buffer size leaving one spare character for string null termination */
+static inline bool telnet_can_insert(struct connection *connection, size_t len)
+{
+       struct telnet_connection *t_con = connection->priv;
+
+       return t_con->line_size + len < TELNET_LINE_MAX_SIZE;
+}
+
+/* write to telnet console, and update the telnet_connection members
+ * this function is capable of inserting in the middle of a line
+ * please ensure that data does not contain special characters (\n, \r, \t, \b ...)
+ *
+ * returns false when it fails to insert the requested data
+ */
+static bool telnet_insert(struct connection *connection, const void *data, size_t len)
+{
+       struct telnet_connection *t_con = connection->priv;
+
+       if (!telnet_can_insert(connection, len)) {
+               telnet_bell(connection);
+               return false;
+       }
+
+       if (t_con->line_cursor < t_con->line_size) {
+               /* we have some content after the cursor */
+               memmove(t_con->line + t_con->line_cursor + len,
+                               t_con->line + t_con->line_cursor,
+                               t_con->line_size - t_con->line_cursor);
+       }
+
+       strncpy(t_con->line + t_con->line_cursor, data, len);
+
+       telnet_write(connection,
+                       t_con->line + t_con->line_cursor,
+                       t_con->line_size + len - t_con->line_cursor);
+
+       t_con->line_size += len;
+       t_con->line_cursor += len;
+
+       for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
+               telnet_write(connection, "\b", 1);
+
+       return true;
+}
+
+static void telnet_delete_character(struct connection *connection)
+{
+       struct telnet_connection *t_con = connection->priv;
+
+       if (t_con->line_cursor == 0)
+               return;
+
+       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);
+       }
+}
+
+static void telnet_remove_character(struct connection *connection)
+{
+       struct telnet_connection *t_con = connection->priv;
+
+       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);
+       }
+}
+
+static int telnet_exec_line(struct connection *connection)
+{
+       struct telnet_connection *t_con = connection->priv;
+       struct command_context *command_context = connection->cmd_ctx;
+       int retval;
+
+       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;
+
+               return ERROR_OK;
+       }
+
+       telnet_history_add(connection);
+
+       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;
+
+       return ERROR_OK;
+}
+
+static void telnet_cut_line_to_end(struct connection *connection)
+{
+       struct telnet_connection *t_con = connection->priv;
+
+       /* FIXME: currently this function does not save to clipboard */
+
+       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;
+       }
+}
+
+static void telnet_interrupt(struct connection *connection)
+{
+       struct telnet_connection *t_con = connection->priv;
+
+       /* print '^C' at line end, and display a new command prompt */
+       telnet_move_cursor(connection, t_con->line_size);
+       telnet_write(connection, "^C\n\r", 4);
+       t_con->line_cursor = 0;
+       t_con->line_size = 0;
+       telnet_prompt(connection);
+}
+
+static void telnet_auto_complete(struct connection *connection)
+{
+       struct telnet_connection *t_con = connection->priv;
+       struct command_context *command_context = connection->cmd_ctx;
+
+       struct cmd_match {
+               char *cmd;
+               struct list_head lh;
+       };
+
+       LIST_HEAD(matches);
+
+       /* - user command sequence, either at line beginning
+        *   or we start over after these characters ';', '[', '{'
+        * - user variable sequence, start after the character '$'
+        *   and do not contain white spaces */
+       bool is_variable_auto_completion = false;
+       bool have_spaces = false;
+       size_t seq_start = (t_con->line_cursor == 0) ? 0 : (t_con->line_cursor - 1);
+       while (1) {
+               char c = t_con->line[seq_start];
+
+               if (c == ';' || c == '[' || c == '{') {
+                       seq_start++;
+                       break;
+               } else if (c == ' ') {
+                       have_spaces = true;
+               } else if (c == '$' && !have_spaces) {
+                       is_variable_auto_completion = true;
+                       seq_start++;
+                       break;
+               }
+
+               if (seq_start == 0)
+                       break;
+
+               seq_start--;
+       }
+
+       /* user command position in the line, ignore leading spaces */
+       size_t usr_cmd_pos = seq_start;
+       while ((usr_cmd_pos < t_con->line_cursor) && isspace(t_con->line[usr_cmd_pos]))
+               usr_cmd_pos++;
+
+       /* check user command length */
+       if (t_con->line_cursor < usr_cmd_pos) {
+               telnet_bell(connection);
+               return;
+       }
+       size_t usr_cmd_len = t_con->line_cursor - usr_cmd_pos;
+
+       /* optimize multiple spaces in the user command,
+        * because info commands does not tolerate multiple spaces */
+       size_t optimized_spaces = 0;
+       char query[usr_cmd_len + 1];
+       for (size_t i = 0; i < usr_cmd_len; i++) {
+               if ((i < usr_cmd_len - 1) && isspace(t_con->line[usr_cmd_pos + i])
+                               && isspace(t_con->line[usr_cmd_pos + i + 1])) {
+                       optimized_spaces++;
+                       continue;
+               }
+
+               query[i - optimized_spaces] = t_con->line[usr_cmd_pos + i];
+       }
+
+       usr_cmd_len -= optimized_spaces;
+       query[usr_cmd_len] = '\0';
+
+       /* filter commands */
+       char *query_cmd;
+
+       if (is_variable_auto_completion)
+               query_cmd = alloc_printf("lsort [info vars {%s*}]", query);
+       else
+               query_cmd = alloc_printf("_telnet_autocomplete_helper {%s*}", query);
+
+       if (!query_cmd) {
+               LOG_ERROR("Out of memory");
+               return;
+       }
+
+       int retval = Jim_EvalSource(command_context->interp, __FILE__, __LINE__, query_cmd);
+       free(query_cmd);
+       if (retval != JIM_OK)
+               return;
+
+       Jim_Obj *list = Jim_GetResult(command_context->interp);
+       Jim_IncrRefCount(list);
+
+       /* common prefix length of the matched commands */
+       size_t common_len = 0;
+       char *first_match = NULL; /* used to compute the common prefix length */
+
+       int len = Jim_ListLength(command_context->interp, list);
+       for (int i = 0; i < len; i++) {
+               Jim_Obj *elem = Jim_ListGetIndex(command_context->interp, list, i);
+               Jim_IncrRefCount(elem);
+
+               char *name = (char *)Jim_GetString(elem, NULL);
+
+               /* validate the command */
+               bool ignore_cmd = false;
+               if (!is_variable_auto_completion) {
+                       Jim_Cmd *jim_cmd = Jim_GetCommand(command_context->interp, elem, JIM_NONE);
+
+                       if (!jim_cmd) {
+                               /* Why we are here? Let's ignore it! */
+                               ignore_cmd = true;
+                       } else if (jimcmd_is_oocd_command(jim_cmd)) {
+                               struct command *cmd = jimcmd_privdata(jim_cmd);
+
+                               if (cmd && !cmd->handler && !cmd->jim_handler) {
+                                       /* Initial part of a multi-word command. Ignore it! */
+                                       ignore_cmd = true;
+                               } else if (cmd && cmd->mode == COMMAND_CONFIG) {
+                                       /* Not executable after config phase. Ignore it! */
+                                       ignore_cmd = true;
+                               }
+                       }
+               }
+
+               /* save the command in the prediction list */
+               if (!ignore_cmd) {
+                       struct cmd_match *match = calloc(1, sizeof(struct cmd_match));
+                       if (!match) {
+                               LOG_ERROR("Out of memory");
+                               Jim_DecrRefCount(command_context->interp, elem);
+                               break; /* break the for loop */
+                       }
+
+                       if (list_empty(&matches)) {
+                               common_len = strlen(name);
+                               first_match = name;
+                       } else {
+                               size_t new_common_len = usr_cmd_len; /* save some loops */
+
+                               while (new_common_len < common_len && first_match[new_common_len] == name[new_common_len])
+                                       new_common_len++;
+
+                               common_len = new_common_len;
+                       }
+
+                       match->cmd = name;
+                       list_add_tail(&match->lh, &matches);
+               }
+
+               Jim_DecrRefCount(command_context->interp, elem);
+       }
+       /* end of command filtering */
+
+       /* proceed with auto-completion */
+       if (list_empty(&matches))
+               telnet_bell(connection);
+       else if (common_len == usr_cmd_len && list_is_singular(&matches) && t_con->line_cursor == t_con->line_size)
+               telnet_insert(connection, " ", 1);
+       else if (common_len > usr_cmd_len) {
+               int completion_size = common_len - usr_cmd_len;
+               if (telnet_insert(connection, first_match + usr_cmd_len, completion_size)) {
+                       /* in bash this extra space is only added when the cursor in at the end of line */
+                       if (list_is_singular(&matches) && t_con->line_cursor == t_con->line_size)
+                               telnet_insert(connection, " ", 1);
+               }
+       } else if (!list_is_singular(&matches)) {
+               telnet_write(connection, "\n\r", 2);
+
+               struct cmd_match *match;
+               list_for_each_entry(match, &matches, lh) {
+                       telnet_write(connection, match->cmd, strlen(match->cmd));
+                       telnet_write(connection, "\n\r", 2);
+               }
+
+               telnet_prompt(connection);
+               telnet_write(connection, t_con->line, t_con->line_size);
+
+               /* restore the terminal visible cursor location */
+               for (size_t i = t_con->line_cursor; i < t_con->line_size; i++)
+                       telnet_write(connection, "\b", 1);
+       }
+
+       /* destroy the command_list */
+       struct cmd_match *tmp, *match;
+       list_for_each_entry_safe(match, tmp, &matches, lh)
+               free(match);
+
+       Jim_DecrRefCount(command_context->interp, list);
+}
+
 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)
-       {
+       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)
-               {
+       while (bytes_read) {
+               switch (t_con->state) {
                        case TELNET_STATE_DATA:
-                               if (*buf_p == 0xff)
-                               {
+                               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 */
-                                                       telnet_write(connection, "\x07", 1); /* "\a" does not work, at least on windows */
-                                               }
-                                               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
-                                               {
-                                                       int 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 */
-                                               {
+                               } else {
+                                       if (isprint(*buf_p)) {  /* printable character */
+                                               telnet_insert(connection, buf_p, 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 */
-                                               {
+                                               } 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)))
-                                                       {
+                                                       if ((bytes_read > 1) && ((*(buf_p + 1) == 0xa) ||
+                                                                       (*(buf_p + 1) == 0xd))) {
                                                                buf_p++;
                                                                bytes_read--;
                                                        }
-                                                       if ((bytes_read > 1) && (*(buf_p + 1) == 0))
-                                                       {
+                                                       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)
-                                                       {
-                                                               int i;
-                                                               for (i = 1; i < TELNET_LINE_HISTORY_SIZE; i++)
-                                                               {
-                                                                       /* the t_con->next_history line contains empty string (unless NULL), thus it is not printed */
-                                                                       char *history_line = t_con->history[(t_con->next_history + i) % TELNET_LINE_HISTORY_SIZE];
-                                                                       if (history_line)
-                                                                       {
-                                                                               telnet_write(connection, history_line, strlen(history_line));
-                                                                               telnet_write(connection, "\r\n\x00", 3);
-                                                                       }
-                                                               }
-                                                               t_con->line_size = 0;
-                                                               t_con->line_cursor = 0;
-                                                               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 */
-                                                               if (t_con->history[t_con->next_history])
-                                                               {
-                                                                       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;
-
-                                                               if (t_con->history[t_con->current_history])
-                                                               {
-                                                                       free(t_con->history[t_con->current_history]);
-                                                               }
-                                                               t_con->history[t_con->current_history] = strdup("");
-                                                       }
-
-                                                       t_con->line_size = 0;
-
-                                                       t_con->line_cursor = -1; /* to supress prompt in log callback during command execution */
-
-                                                       retval = command_run_line(command_context, t_con->line);
-
-                                                       t_con->line_cursor = 0;
-
-                                                       if (retval == ERROR_COMMAND_CLOSE_CONNECTION)
-                                                               return ERROR_SERVER_REMOTE_CLOSED;
-
-                                                       telnet_write(connection, "\r", 1); /* the prompt is always placed at the line beginning */
-                                                       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)
-                                                               {
-                                                                       int 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 */
-                                               {
+                                                       retval = telnet_exec_line(connection);
+                                                       if (retval != ERROR_OK)
+                                                               return retval;
+                                               } else if ((*buf_p == 0x7f) || (*buf_p == 0x8)) {       /* delete character */
+                                                       telnet_delete_character(connection);
+                                               } 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--;
-                                                       }
+                                               } else if (*buf_p == CTRL('B')) {       /* cursor left */
+                                                       telnet_move_cursor(connection, t_con->line_cursor - 1);
                                                        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);
-                                                       }
+                                               } else if (*buf_p == CTRL('C')) {       /* interrupt */
+                                                       telnet_interrupt(connection);
+                                               } else if (*buf_p == CTRL('F')) {       /* cursor right */
+                                                       telnet_move_cursor(connection, t_con->line_cursor + 1);
                                                        t_con->state = TELNET_STATE_DATA;
-                                               }
-                                               else
-                                               {
+                                               } 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')) {       /* move the cursor to the beginning of the line */
+                                                       telnet_move_cursor(connection, 0);
+                                               } else if (*buf_p == CTRL('E')) {       /* move the cursor to the end of the line */
+                                                       telnet_move_cursor(connection, t_con->line_size);
+                                               } else if (*buf_p == CTRL('K')) {       /* kill line to end */
+                                                       telnet_cut_line_to_end(connection);
+                                               } else if (*buf_p == '\t') {
+                                                       telnet_auto_complete(connection);
+                                               } 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;
+                               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:
@@ -425,106 +851,41 @@ static int telnet_input(struct connection *connection)
                                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--;
-                                               }
+                               if (t_con->last_escape == '[') {
+                                       if (*buf_p == 'D') {    /* cursor left */
+                                               telnet_move_cursor(connection, t_con->line_cursor - 1);
                                                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);
-                                               }
+                                       } else if (*buf_p == 'C') {     /* cursor right */
+                                               telnet_move_cursor(connection, t_con->line_cursor + 1);
                                                t_con->state = TELNET_STATE_DATA;
-                                       }
-                                       else if (*buf_p == 'A') /* cursor up */
-                                       {
-                                               int last_history = (t_con->current_history > 0) ? t_con->current_history - 1 : TELNET_LINE_HISTORY_SIZE-1;
-                                               if (t_con->history[last_history])
-                                               {
-                                                       telnet_clear_line(connection, t_con);
-                                                       t_con->line_size = strlen(t_con->history[last_history]);
-                                                       t_con->line_cursor = t_con->line_size;
-                                                       memcpy(t_con->line, t_con->history[last_history], t_con->line_size);
-                                                       telnet_write(connection, t_con->line, t_con->line_size);
-                                                       t_con->current_history = last_history;
-                                               }
+                                       } 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 == 'F') { /* end key */
+                                               telnet_move_cursor(connection, t_con->line_size);
                                                t_con->state = TELNET_STATE_DATA;
-                                       }
-                                       else if (*buf_p == 'B') /* cursor down */
-                                       {
-                                               int next_history = (t_con->current_history + 1) % TELNET_LINE_HISTORY_SIZE;
-                                               if (t_con->history[next_history])
-                                               {
-                                                       telnet_clear_line(connection, t_con);
-                                                       t_con->line_size = strlen(t_con->history[next_history]);
-                                                       t_con->line_cursor = t_con->line_size;
-                                                       memcpy(t_con->line, t_con->history[next_history], t_con->line_size);
-                                                       telnet_write(connection, t_con->line, t_con->line_size);
-                                                       t_con->current_history = next_history;
-                                               }
+                                       } else if (*buf_p == 'H') { /* home key */
+                                               telnet_move_cursor(connection, 0);
                                                t_con->state = TELNET_STATE_DATA;
-                                       }
-                                       else if (*buf_p == '3')
-                                       {
+                                       } else if (*buf_p == '3') {
                                                t_con->last_escape = *buf_p;
-                                       }
-                                       else
-                                       {
+                                       } else {
                                                t_con->state = TELNET_STATE_DATA;
                                        }
-                               }
-                               else if (t_con->last_escape == '3')
-                               {
+                               } else if (t_con->last_escape == '3') {
                                        /* Remove character */
-                                       if (*buf_p == '~')
-                                       {
-                                               if (t_con->line_cursor < t_con->line_size)
-                                               {
-                                                       int 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);
-                                                       }
-                                               }
-
+                                       if (*buf_p == '~') {
+                                               telnet_remove_character(connection);
                                                t_con->state = TELNET_STATE_DATA;
-                                       }
-                                       else
-                                       {
+                                       } else
                                                t_con->state = TELNET_STATE_DATA;
-                                       }
-                               }
-                               else if (t_con->last_escape == '\x00')
-                               {
+                               } else if (t_con->last_escape == '\x00') {
                                        if (*buf_p == '[')
-                                       {
                                                t_con->last_escape = *buf_p;
-                                       }
                                        else
-                                       {
                                                t_con->state = TELNET_STATE_DATA;
-                                       }
-                               }
-                               else
-                               {
+                               } else {
                                        LOG_ERROR("BUG: unexpected value in t_con->last_escape");
                                        t_con->state = TELNET_STATE_DATA;
                                }
@@ -532,7 +893,7 @@ static int telnet_input(struct connection *connection)
                                break;
                        default:
                                LOG_ERROR("unknown telnet state");
-                               exit(-1);
+                               return ERROR_FAIL;
                }
 
                bytes_read--;
@@ -549,51 +910,59 @@ static int telnet_connection_closed(struct connection *connection)
 
        log_remove_callback(telnet_log_callback, connection);
 
-       if (t_con->prompt)
-       {
-               free(t_con->prompt);
-               t_con->prompt = NULL;
-       }
+       free(t_con->prompt);
+       t_con->prompt = NULL;
 
-       for (i = 0; i < TELNET_LINE_HISTORY_SIZE; i++)
-       {
-               if (t_con->history[i])
-               {
-                       free(t_con->history[i]);
-                       t_con->history[i] = 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);
 
-       if (connection->priv)
-       {
-               free(connection->priv);
-               connection->priv = NULL;
-       }
-       else
-       {
-               LOG_ERROR("BUG: connection->priv == NULL");
-       }
+       free(connection->priv);
+       connection->priv = NULL;
 
        return ERROR_OK;
 }
 
+static const struct service_driver telnet_service_driver = {
+       .name = "telnet",
+       .new_connection_during_keep_alive_handler = NULL,
+       .new_connection_handler = telnet_new_connection,
+       .input_handler = telnet_input,
+       .connection_closed_handler = telnet_connection_closed,
+       .keep_client_alive_handler = NULL,
+};
+
 int telnet_init(char *banner)
 {
-       struct telnet_service *telnet_service = malloc(sizeof(struct telnet_service));
-
-       if (telnet_port == 0)
-       {
-               LOG_INFO("telnet port disabled");
-               free(telnet_service);
+       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;
 
-       add_service("telnet", CONNECTION_TCP, telnet_port, 1, telnet_new_connection, telnet_input, telnet_connection_closed, telnet_service);
+       int ret = add_service(&telnet_service_driver, telnet_port, CONNECTION_LIMIT_UNLIMITED,
+               telnet_service);
+
+       if (ret != ERROR_OK) {
+               free(telnet_service);
+               return ret;
+       }
 
        return ERROR_OK;
 }
@@ -601,7 +970,7 @@ int telnet_init(char *banner)
 /* daemon configuration command telnet_port */
 COMMAND_HANDLER(handle_telnet_port_command)
 {
-       return CALL_COMMAND_HANDLER(server_port_command, &telnet_port);
+       return CALL_COMMAND_HANDLER(server_pipe_command, &telnet_port);
 }
 
 COMMAND_HANDLER(handle_exit_command)
@@ -614,15 +983,16 @@ 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_ANY,
+               .mode = COMMAND_CONFIG,
                .help = "Specify port on which to listen "
                        "for incoming telnet connections.  "
-                       "No arguments reports telnet port; zero disables.",
+                       "Read help on 'gdb_port'.",
                .usage = "[port_num]",
        },
        COMMAND_REGISTRATION_DONE
@@ -630,5 +1000,11 @@ static const struct command_registration telnet_command_handlers[] = {
 
 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);
+}