1 | /** |
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2 | * @file |
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3 | * |
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4 | * @brief The telnet DAEMON |
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5 | * |
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6 | * After start the net you can start this daemon. |
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7 | * It uses the previously inited pseudo-terminales (pty.c) |
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8 | * getting a new terminal with getpty(). This function |
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9 | * gives a terminal name passing a opened socket like parameter. |
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10 | * |
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11 | * With register_telnetd() you add a new command in the shell to start |
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12 | * this daemon interactively. (Login in /dev/console of course) |
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13 | * |
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14 | * Sorry but OOB is not still implemented. (This is the first version) |
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15 | */ |
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16 | |
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17 | /* |
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18 | * Copyright (c) 2001 Fernando Ruiz Casas <fruizcasas@gmail.com> |
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19 | * |
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20 | * Till Straumann <strauman@slac.stanford.edu> |
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21 | * - made the 'shell' interface more generic, i.e. it is now |
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22 | * possible to have 'telnetd' run an arbitrary 'shell' |
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23 | * program. |
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24 | * |
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25 | * Copyright (C) 2009, 2018 embedded brains GmbH & Co. KG |
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26 | * |
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27 | * The license and distribution terms for this file may be |
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28 | * found in the file LICENSE in this distribution or at |
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29 | * http://www.rtems.org/license/LICENSE. |
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30 | */ |
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31 | |
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32 | #ifdef HAVE_CONFIG_H |
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33 | #include "config.h" |
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34 | #endif |
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35 | |
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36 | #include <sys/queue.h> |
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37 | #include <sys/socket.h> |
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38 | #include <netinet/in.h> |
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39 | #include <arpa/inet.h> |
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40 | #include <inttypes.h> |
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41 | #include <unistd.h> |
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42 | #include <stdlib.h> |
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43 | #include <stdio.h> |
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44 | #include <string.h> |
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45 | #include <syslog.h> |
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46 | |
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47 | #include <rtems.h> |
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48 | #include <rtems/pty.h> |
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49 | #include <rtems/shell.h> |
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50 | #include <rtems/telnetd.h> |
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51 | #include <rtems/thread.h> |
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52 | #include <rtems/userenv.h> |
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53 | |
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54 | #define TELNETD_EVENT_SUCCESS RTEMS_EVENT_0 |
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55 | |
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56 | #define TELNETD_EVENT_ERROR RTEMS_EVENT_1 |
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57 | |
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58 | typedef struct telnetd_context telnetd_context; |
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59 | |
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60 | typedef struct telnetd_session { |
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61 | rtems_pty_context pty; |
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62 | char peername[16]; |
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63 | telnetd_context *ctx; |
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64 | rtems_id task_id; |
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65 | LIST_ENTRY(telnetd_session) link; |
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66 | } telnetd_session; |
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67 | |
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68 | struct telnetd_context { |
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69 | rtems_telnetd_config_table config; |
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70 | int server_socket; |
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71 | rtems_id task_id; |
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72 | rtems_mutex mtx; |
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73 | LIST_HEAD(, telnetd_session) free_sessions; |
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74 | telnetd_session sessions[RTEMS_ZERO_LENGTH_ARRAY]; |
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75 | }; |
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76 | |
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77 | typedef union { |
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78 | struct sockaddr_in sin; |
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79 | struct sockaddr sa; |
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80 | } telnetd_address; |
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81 | |
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82 | RTEMS_NO_RETURN static void telnetd_session_fatal_error( |
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83 | const telnetd_context *ctx |
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84 | ) |
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85 | { |
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86 | (void)rtems_event_send(ctx->task_id, TELNETD_EVENT_ERROR); |
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87 | rtems_task_exit(); |
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88 | } |
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89 | |
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90 | static bool telnetd_login(telnetd_context *ctx, telnetd_session *session) |
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91 | { |
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92 | bool success; |
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93 | |
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94 | if (ctx->config.login_check == NULL) { |
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95 | return true; |
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96 | } |
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97 | |
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98 | success = rtems_shell_login_prompt( |
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99 | stdin, |
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100 | stderr, |
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101 | session->pty.name, |
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102 | ctx->config.login_check |
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103 | ); |
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104 | |
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105 | if (!success) { |
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106 | syslog( |
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107 | LOG_AUTHPRIV | LOG_WARNING, |
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108 | "telnetd: too many wrong passwords entered from %s", |
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109 | session->peername |
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110 | ); |
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111 | } |
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112 | |
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113 | return success; |
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114 | } |
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115 | |
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116 | static void telnetd_session_task(rtems_task_argument arg) |
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117 | { |
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118 | rtems_status_code sc; |
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119 | telnetd_session *session; |
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120 | telnetd_context *ctx; |
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121 | const char *path; |
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122 | |
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123 | session = (telnetd_session *) arg; |
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124 | ctx = session->ctx; |
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125 | |
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126 | sc = rtems_libio_set_private_env(); |
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127 | if (sc != RTEMS_SUCCESSFUL) { |
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128 | telnetd_session_fatal_error(ctx); |
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129 | } |
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130 | |
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131 | path = rtems_pty_get_path(&session->pty); |
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132 | |
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133 | stdin = fopen(path, "r+"); |
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134 | if (stdin == NULL) { |
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135 | telnetd_session_fatal_error(ctx); |
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136 | } |
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137 | |
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138 | stdout = fopen(path, "r+"); |
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139 | if (stdout == NULL) { |
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140 | telnetd_session_fatal_error(ctx); |
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141 | } |
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142 | |
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143 | stderr = fopen(path, "r+"); |
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144 | if (stderr == NULL) { |
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145 | telnetd_session_fatal_error(ctx); |
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146 | } |
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147 | |
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148 | (void)rtems_event_send(ctx->task_id, TELNETD_EVENT_SUCCESS); |
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149 | |
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150 | while (true) { |
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151 | rtems_event_set events; |
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152 | |
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153 | (void)rtems_event_system_receive( |
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154 | RTEMS_EVENT_SYSTEM_SERVER, |
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155 | RTEMS_WAIT | RTEMS_EVENT_ALL, |
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156 | RTEMS_NO_TIMEOUT, |
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157 | &events |
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158 | ); |
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159 | |
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160 | syslog( |
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161 | LOG_DAEMON | LOG_INFO, |
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162 | "telnetd: accepted connection from %s on %s", |
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163 | session->peername, |
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164 | path |
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165 | ); |
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166 | |
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167 | if (telnetd_login(ctx, session)) { |
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168 | (*ctx->config.command)(session->pty.name, ctx->config.arg); |
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169 | } |
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170 | |
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171 | syslog( |
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172 | LOG_DAEMON | LOG_INFO, |
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173 | "telnetd: releasing connection from %s on %s", |
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174 | session->peername, |
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175 | path |
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176 | ); |
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177 | |
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178 | rtems_pty_close_socket(&session->pty); |
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179 | |
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180 | rtems_mutex_lock(&ctx->mtx); |
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181 | LIST_INSERT_HEAD(&ctx->free_sessions, session, link); |
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182 | rtems_mutex_unlock(&ctx->mtx); |
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183 | } |
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184 | } |
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185 | |
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186 | static void telnetd_sleep_after_error(void) |
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187 | { |
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188 | /* If something went wrong, sleep for some time */ |
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189 | rtems_task_wake_after(10 * rtems_clock_get_ticks_per_second()); |
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190 | } |
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191 | |
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192 | static void telnetd_server_task(rtems_task_argument arg) |
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193 | { |
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194 | telnetd_context *ctx; |
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195 | |
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196 | ctx = (telnetd_context *) arg; |
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197 | |
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198 | while (true) { |
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199 | telnetd_address peer; |
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200 | socklen_t address_len; |
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201 | int session_socket; |
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202 | telnetd_session *session; |
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203 | |
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204 | address_len = sizeof(peer.sin); |
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205 | session_socket = accept(ctx->server_socket, &peer.sa, &address_len); |
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206 | if (session_socket < 0) { |
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207 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot accept session"); |
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208 | telnetd_sleep_after_error(); |
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209 | continue; |
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210 | }; |
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211 | |
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212 | rtems_mutex_lock(&ctx->mtx); |
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213 | session = LIST_FIRST(&ctx->free_sessions); |
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214 | |
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215 | if (session == NULL) { |
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216 | rtems_mutex_unlock(&ctx->mtx); |
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217 | |
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218 | (void)close(session_socket); |
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219 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: no free session available"); |
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220 | telnetd_sleep_after_error(); |
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221 | continue; |
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222 | } |
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223 | |
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224 | LIST_REMOVE(session, link); |
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225 | rtems_mutex_unlock(&ctx->mtx); |
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226 | |
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227 | rtems_pty_set_socket(&session->pty, session_socket); |
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228 | |
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229 | if ( |
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230 | inet_ntop( |
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231 | AF_INET, |
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232 | &peer.sin.sin_addr, |
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233 | session->peername, |
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234 | sizeof(session->peername) |
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235 | ) == NULL |
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236 | ) { |
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237 | strlcpy(session->peername, "<UNKNOWN>", sizeof(session->peername)); |
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238 | } |
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239 | |
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240 | (void)rtems_event_system_send(session->task_id, RTEMS_EVENT_SYSTEM_SERVER); |
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241 | } |
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242 | } |
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243 | |
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244 | static void telnetd_destroy_context(telnetd_context *ctx) |
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245 | { |
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246 | telnetd_session *session; |
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247 | |
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248 | LIST_FOREACH(session, &ctx->free_sessions, link) { |
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249 | if (session->task_id != 0) { |
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250 | (void)rtems_task_delete(session->task_id); |
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251 | } |
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252 | |
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253 | (void)unlink(rtems_pty_get_path(&session->pty)); |
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254 | } |
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255 | |
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256 | if (ctx->server_socket >= 0) { |
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257 | (void)close(ctx->server_socket); |
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258 | } |
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259 | |
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260 | rtems_mutex_destroy(&ctx->mtx); |
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261 | free(ctx); |
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262 | } |
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263 | |
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264 | static rtems_status_code telnetd_create_server_socket(telnetd_context *ctx) |
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265 | { |
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266 | telnetd_address srv; |
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267 | socklen_t address_len; |
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268 | int enable; |
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269 | |
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270 | ctx->server_socket = socket(PF_INET, SOCK_STREAM, 0); |
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271 | if (ctx->server_socket < 0) { |
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272 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create server socket"); |
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273 | return RTEMS_UNSATISFIED; |
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274 | } |
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275 | |
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276 | enable = 1; |
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277 | (void)setsockopt( |
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278 | ctx->server_socket, |
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279 | SOL_SOCKET, |
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280 | SO_KEEPALIVE, |
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281 | &enable, |
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282 | sizeof(enable) |
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283 | ); |
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284 | |
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285 | memset(&srv, 0, sizeof(srv)); |
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286 | srv.sin.sin_family = AF_INET; |
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287 | srv.sin.sin_port = htons(ctx->config.port); |
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288 | address_len = sizeof(srv.sin); |
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289 | |
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290 | if (bind(ctx->server_socket, &srv.sa, address_len) != 0) { |
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291 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot bind server socket"); |
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292 | return RTEMS_RESOURCE_IN_USE; |
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293 | }; |
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294 | |
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295 | if (listen(ctx->server_socket, ctx->config.client_maximum) != 0) { |
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296 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot listen on server socket"); |
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297 | return RTEMS_UNSATISFIED; |
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298 | }; |
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299 | |
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300 | return RTEMS_SUCCESSFUL; |
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301 | } |
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302 | |
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303 | static rtems_status_code telnetd_create_session_tasks(telnetd_context *ctx) |
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304 | { |
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305 | uint16_t i; |
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306 | |
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307 | ctx->task_id = rtems_task_self(); |
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308 | |
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309 | for (i = 0; i < ctx->config.client_maximum; ++i) { |
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310 | telnetd_session *session; |
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311 | rtems_status_code sc; |
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312 | const char *path; |
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313 | rtems_event_set events; |
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314 | |
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315 | session = &ctx->sessions[i]; |
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316 | session->ctx = ctx; |
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317 | rtems_mutex_init(&ctx->mtx, "Telnet"); |
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318 | LIST_INSERT_HEAD(&ctx->free_sessions, session, link); |
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319 | |
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320 | sc = rtems_task_create( |
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321 | rtems_build_name('T', 'N', 'T', 'a' + i % 26), |
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322 | ctx->config.priority, |
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323 | ctx->config.stack_size, |
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324 | RTEMS_DEFAULT_MODES, |
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325 | RTEMS_FLOATING_POINT, |
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326 | &session->task_id |
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327 | ); |
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328 | if (sc != RTEMS_SUCCESSFUL) { |
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329 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create session task"); |
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330 | return RTEMS_UNSATISFIED; |
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331 | } |
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332 | |
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333 | path = rtems_pty_initialize(&session->pty, i); |
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334 | if (path == NULL) { |
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335 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create session PTY"); |
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336 | return RTEMS_UNSATISFIED; |
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337 | } |
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338 | |
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339 | (void)rtems_task_start( |
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340 | session->task_id, |
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341 | telnetd_session_task, |
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342 | (rtems_task_argument) session |
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343 | ); |
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344 | |
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345 | (void)rtems_event_receive( |
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346 | TELNETD_EVENT_SUCCESS | TELNETD_EVENT_ERROR, |
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347 | RTEMS_WAIT | RTEMS_EVENT_ANY, |
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348 | RTEMS_NO_TIMEOUT, |
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349 | &events |
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350 | ); |
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351 | |
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352 | if ((events & TELNETD_EVENT_ERROR) != 0) { |
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353 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot initialize session task"); |
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354 | return RTEMS_UNSATISFIED; |
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355 | } |
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356 | } |
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357 | |
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358 | return RTEMS_SUCCESSFUL; |
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359 | } |
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360 | |
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361 | rtems_status_code rtems_telnetd_start(const rtems_telnetd_config_table* config) |
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362 | { |
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363 | telnetd_context *ctx; |
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364 | rtems_status_code sc; |
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365 | uint16_t client_maximum; |
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366 | |
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367 | if (config->command == NULL) { |
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368 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: configuration with invalid command"); |
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369 | return RTEMS_INVALID_ADDRESS; |
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370 | } |
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371 | |
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372 | if (config->client_maximum == 0) { |
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373 | client_maximum = 5; |
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374 | } else { |
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375 | client_maximum = config->client_maximum; |
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376 | } |
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377 | |
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378 | ctx = calloc( |
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379 | 1, |
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380 | sizeof(*ctx) + client_maximum * sizeof(ctx->sessions[0]) |
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381 | ); |
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382 | if (ctx == NULL) { |
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383 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot allocate server context"); |
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384 | return RTEMS_UNSATISFIED; |
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385 | } |
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386 | |
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387 | ctx->config = *config; |
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388 | ctx->config.client_maximum = client_maximum; |
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389 | ctx->server_socket = -1; |
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390 | LIST_INIT(&ctx->free_sessions); |
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391 | |
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392 | /* Set priority */ |
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393 | if (ctx->config.priority == 0) { |
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394 | ctx->config.priority = 100; |
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395 | } |
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396 | |
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397 | /* Check stack size */ |
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398 | if (ctx->config.stack_size == 0) { |
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399 | ctx->config.stack_size = (size_t)32 * 1024; |
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400 | } |
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401 | |
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402 | if (ctx->config.port == 0) { |
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403 | ctx->config.port = 23; |
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404 | } |
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405 | |
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406 | sc = telnetd_create_server_socket(ctx); |
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407 | if (sc != RTEMS_SUCCESSFUL) { |
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408 | telnetd_destroy_context(ctx); |
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409 | return sc; |
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410 | } |
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411 | |
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412 | sc = telnetd_create_session_tasks(ctx); |
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413 | if (sc != RTEMS_SUCCESSFUL) { |
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414 | telnetd_destroy_context(ctx); |
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415 | return sc; |
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416 | } |
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417 | |
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418 | sc = rtems_task_create( |
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419 | rtems_build_name('T', 'N', 'T', 'D'), |
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420 | ctx->config.priority, |
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421 | RTEMS_MINIMUM_STACK_SIZE, |
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422 | RTEMS_DEFAULT_MODES, |
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423 | RTEMS_FLOATING_POINT, |
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424 | &ctx->task_id |
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425 | ); |
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426 | if (sc != RTEMS_SUCCESSFUL) { |
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427 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create server task"); |
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428 | telnetd_destroy_context(ctx); |
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429 | return RTEMS_UNSATISFIED; |
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430 | } |
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431 | |
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432 | (void)rtems_task_start( |
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433 | ctx->task_id, |
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434 | telnetd_server_task, |
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435 | (rtems_task_argument) ctx |
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436 | ); |
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437 | |
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438 | syslog( |
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439 | LOG_DAEMON | LOG_INFO, |
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440 | "telnetd: started successfully on port %" PRIu16, ctx->config.port |
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441 | ); |
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442 | return RTEMS_SUCCESSFUL; |
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443 | } |
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