1 | /***********************************************************/ |
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2 | /* |
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3 | * |
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4 | * The telnet DAEMON |
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5 | * |
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6 | * Author: 17,may 2001 |
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7 | * |
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8 | * WORK: fernando.ruiz@ctv.es |
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9 | * HOME: correo@fernando-ruiz.com |
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10 | * |
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11 | * After start the net you can start this daemon. |
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12 | * It uses the previously inited pseudo-terminales (pty.c) |
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13 | * getting a new terminal with getpty(). This function |
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14 | * gives a terminal name passing a opened socket like parameter. |
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15 | * |
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16 | * With register_telnetd() you add a new command in the shell to start |
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17 | * this daemon interactively. (Login in /dev/console of course) |
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18 | * |
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19 | * Sorry but OOB is not still implemented. (This is the first version) |
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20 | * |
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21 | * Till Straumann <strauman@slac.stanford.edu> |
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22 | * - made the 'shell' interface more generic, i.e. it is now |
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23 | * possible to have 'telnetd' run an arbitrary 'shell' |
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24 | * program. |
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25 | * |
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26 | * Copyright (c) 2009 embedded brains GmbH and others. |
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27 | * |
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28 | * embedded brains GmbH |
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29 | * Obere Lagerstr. 30 |
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30 | * D-82178 Puchheim |
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31 | * Germany |
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32 | * <rtems@embedded-brains.de> |
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33 | * |
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34 | * The license and distribution terms for this file may be |
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35 | * found in the file LICENSE in this distribution or at |
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36 | * http://www.rtems.org/license/LICENSE. |
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37 | */ |
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38 | |
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39 | #ifdef HAVE_CONFIG_H |
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40 | #include "config.h" |
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41 | #endif |
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42 | |
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43 | #include <sys/socket.h> |
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44 | #include <netinet/in.h> |
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45 | #include <arpa/inet.h> |
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46 | #include <unistd.h> |
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47 | #include <stdlib.h> |
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48 | #include <stdio.h> |
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49 | #include <string.h> |
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50 | #include <syslog.h> |
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51 | |
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52 | #include <rtems.h> |
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53 | #include <rtems/error.h> |
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54 | #include <rtems/pty.h> |
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55 | #include <rtems/shell.h> |
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56 | #include <rtems/telnetd.h> |
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57 | #include <rtems/userenv.h> |
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58 | |
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59 | #ifdef RTEMS_NETWORKING |
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60 | #include <rtems/rtems_bsdnet.h> |
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61 | #endif |
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62 | |
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63 | #define PARANOIA |
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64 | |
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65 | typedef struct telnetd_context telnetd_context; |
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66 | |
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67 | struct shell_args { |
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68 | rtems_pty_context pty; |
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69 | char peername[16]; |
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70 | telnetd_context *ctx; |
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71 | }; |
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72 | |
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73 | struct telnetd_context { |
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74 | rtems_telnetd_config_table config; |
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75 | uint16_t active_clients; |
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76 | }; |
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77 | |
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78 | typedef union uni_sa { |
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79 | struct sockaddr_in sin; |
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80 | struct sockaddr sa; |
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81 | } uni_sa; |
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82 | |
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83 | static int sockpeername(int sock, char *buf, int bufsz); |
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84 | |
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85 | rtems_id telnetd_dflt_spawn( |
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86 | const char *name, |
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87 | unsigned priority, |
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88 | unsigned stackSize, |
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89 | void (*fn)(void*), |
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90 | void *fnarg |
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91 | ); |
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92 | |
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93 | /***********************************************************/ |
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94 | static telnetd_context telnetd_instance; |
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95 | |
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96 | /* |
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97 | * chrisj: this variable was global and with no declared interface in a header |
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98 | * file and with no means to set it so I have stopped it being global; |
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99 | * if this breaks any user they will have be to provide a formal |
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100 | * interface to get this change reverted. |
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101 | */ |
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102 | static const rtems_id (*telnetd_spawn_task)( |
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103 | const char *, |
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104 | unsigned, |
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105 | unsigned, |
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106 | void (*)(void*), |
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107 | void * |
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108 | ) = telnetd_dflt_spawn; |
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109 | |
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110 | static struct shell_args *grab_a_Connection( |
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111 | telnetd_context *ctx, |
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112 | int des_socket, |
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113 | uni_sa *srv, |
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114 | char *peername, |
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115 | int sz |
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116 | ) |
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117 | { |
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118 | struct shell_args *args; |
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119 | socklen_t size_adr = sizeof(srv->sin); |
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120 | int acp_sock; |
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121 | |
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122 | if (ctx->active_clients >= ctx->config.client_maximum) { |
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123 | return NULL; |
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124 | } |
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125 | |
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126 | args = malloc(sizeof(*args)); |
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127 | if (args == NULL) { |
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128 | perror("telnetd:malloc"); |
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129 | return NULL; |
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130 | } |
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131 | |
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132 | acp_sock = accept(des_socket,&srv->sa,&size_adr); |
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133 | if (acp_sock<0) { |
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134 | perror("telnetd:accept"); |
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135 | free(args); |
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136 | return NULL; |
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137 | }; |
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138 | |
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139 | if (telnet_get_pty(&args->pty, acp_sock) == NULL) { |
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140 | syslog( LOG_DAEMON | LOG_ERR, "telnetd: unable to obtain PTY"); |
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141 | /* NOTE: failing 'do_get_pty()' closed the socket */ |
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142 | free(args); |
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143 | return NULL; |
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144 | } |
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145 | |
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146 | if (sockpeername(acp_sock, peername, sz)) |
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147 | strncpy(peername, "<UNKNOWN>", sz); |
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148 | |
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149 | #ifdef PARANOIA |
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150 | syslog(LOG_DAEMON | LOG_INFO, |
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151 | "telnetd: accepted connection from %s on %s", |
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152 | peername, |
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153 | args->pty.name); |
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154 | #endif |
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155 | |
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156 | ++ctx->active_clients; |
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157 | args->ctx = ctx; |
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158 | return args; |
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159 | } |
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160 | |
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161 | |
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162 | static void release_a_Connection(telnetd_context *ctx, const char *devname, |
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163 | const char *peername, FILE **pstd, int n) |
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164 | { |
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165 | |
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166 | #ifdef PARANOIA |
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167 | syslog( LOG_DAEMON | LOG_INFO, |
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168 | "telnetd: releasing connection from %s on %s", |
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169 | peername, |
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170 | devname ); |
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171 | #endif |
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172 | |
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173 | --ctx->active_clients; |
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174 | |
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175 | while (--n>=0) |
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176 | if (pstd[n]) fclose(pstd[n]); |
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177 | |
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178 | unlink(devname); |
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179 | } |
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180 | |
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181 | static int sockpeername(int sock, char *buf, int bufsz) |
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182 | { |
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183 | uni_sa peer; |
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184 | int rval = sock < 0; |
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185 | socklen_t len = sizeof(peer.sin); |
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186 | |
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187 | if ( !rval ) |
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188 | rval = getpeername(sock, &peer.sa, &len); |
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189 | |
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190 | if ( !rval ) |
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191 | rval = !inet_ntop( AF_INET, &peer.sin.sin_addr, buf, bufsz ); |
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192 | |
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193 | return rval; |
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194 | } |
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195 | |
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196 | static void |
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197 | spawned_shell(void *arg); |
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198 | |
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199 | /***********************************************************/ |
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200 | static void |
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201 | rtems_task_telnetd(void *task_argument) |
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202 | { |
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203 | int des_socket; |
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204 | uni_sa srv; |
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205 | char peername[16]; |
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206 | int i=1; |
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207 | int size_adr; |
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208 | struct shell_args *arg = NULL; |
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209 | rtems_id task_id; |
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210 | telnetd_context *ctx = task_argument; |
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211 | |
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212 | if ((des_socket=socket(PF_INET,SOCK_STREAM,0))<0) { |
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213 | perror("telnetd:socket"); |
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214 | rtems_task_exit(); |
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215 | }; |
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216 | (void)setsockopt(des_socket,SOL_SOCKET,SO_KEEPALIVE,&i,sizeof(i)); |
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217 | |
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218 | memset(&srv,0,sizeof(srv)); |
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219 | srv.sin.sin_family=AF_INET; |
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220 | srv.sin.sin_port=htons(23); |
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221 | size_adr=sizeof(srv.sin); |
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222 | if ((bind(des_socket,&srv.sa,size_adr))<0) { |
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223 | perror("telnetd:bind"); |
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224 | close(des_socket); |
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225 | rtems_task_exit(); |
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226 | }; |
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227 | if ((listen(des_socket,5))<0) { |
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228 | perror("telnetd:listen"); |
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229 | close(des_socket); |
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230 | rtems_task_exit(); |
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231 | }; |
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232 | |
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233 | /* we don't redirect stdio as this probably |
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234 | * was started from the console anyway .. |
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235 | */ |
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236 | do { |
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237 | arg = grab_a_Connection(ctx, des_socket, &srv, peername, |
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238 | sizeof(peername)); |
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239 | |
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240 | if (arg == NULL) { |
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241 | /* if something went wrong, sleep for some time */ |
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242 | sleep(10); |
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243 | continue; |
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244 | } |
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245 | |
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246 | strncpy(arg->peername, peername, sizeof(arg->peername)); |
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247 | |
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248 | task_id = telnetd_spawn_task( |
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249 | arg->pty.name, |
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250 | ctx->config.priority, |
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251 | ctx->config.stack_size, |
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252 | spawned_shell, |
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253 | arg |
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254 | ); |
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255 | if (task_id == RTEMS_ID_NONE) { |
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256 | FILE *dummy; |
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257 | |
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258 | if ( telnetd_spawn_task != telnetd_dflt_spawn ) { |
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259 | fprintf(stderr,"Telnetd: Unable to spawn child task\n"); |
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260 | } |
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261 | |
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262 | /* hmm - the pty driver slot can only be |
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263 | * released by opening and subsequently |
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264 | * closing the PTY - this also closes |
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265 | * the underlying socket. So we mock up |
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266 | * a stream... |
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267 | */ |
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268 | |
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269 | if ( !(dummy=fopen(arg->pty.name,"r+")) ) |
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270 | perror("Unable to dummy open the pty, losing a slot :-("); |
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271 | release_a_Connection(ctx, arg->pty.name, peername, &dummy, 1); |
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272 | free(arg); |
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273 | sleep(2); /* don't accept connections too fast */ |
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274 | } |
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275 | } while(1); |
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276 | |
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277 | /* TODO: how to free the connection semaphore? But then - |
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278 | * stopping the daemon is probably only needed during |
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279 | * development/debugging. |
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280 | * Finalizer code should collect all the connection semaphore |
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281 | * counts and eventually clean up... |
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282 | */ |
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283 | close(des_socket); |
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284 | } |
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285 | |
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286 | rtems_status_code rtems_telnetd_start(const rtems_telnetd_config_table* config) |
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287 | { |
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288 | telnetd_context *ctx = &telnetd_instance; |
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289 | rtems_id task_id; |
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290 | |
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291 | if (config->command == NULL) { |
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292 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: configuration with invalid command"); |
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293 | return RTEMS_INVALID_ADDRESS; |
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294 | } |
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295 | |
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296 | if (ctx->config.command != NULL) { |
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297 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: already started"); |
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298 | return RTEMS_RESOURCE_IN_USE; |
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299 | } |
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300 | |
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301 | ctx->config = *config; |
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302 | |
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303 | /* Check priority */ |
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304 | #ifdef RTEMS_NETWORKING |
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305 | if (ctx->config.priority == 0) { |
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306 | ctx->config.priority = rtems_bsdnet_config.network_task_priority; |
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307 | } |
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308 | #endif |
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309 | if (ctx->config.priority == 0) { |
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310 | ctx->config.priority = 100; |
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311 | } |
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312 | |
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313 | /* Check stack size */ |
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314 | if (ctx->config.stack_size == 0) { |
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315 | ctx->config.stack_size = (size_t)32 * 1024; |
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316 | } |
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317 | |
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318 | if (ctx->config.client_maximum == 0) { |
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319 | ctx->config.client_maximum = 5; |
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320 | } |
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321 | |
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322 | /* Spawn task */ |
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323 | task_id = telnetd_spawn_task( |
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324 | "TNTD", |
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325 | ctx->config.priority, |
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326 | ctx->config.stack_size, |
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327 | rtems_task_telnetd, |
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328 | ctx |
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329 | ); |
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330 | if (task_id == RTEMS_ID_NONE) { |
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331 | ctx->config.command = NULL; |
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332 | syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create server task"); |
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333 | return RTEMS_UNSATISFIED; |
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334 | } |
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335 | |
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336 | syslog(LOG_DAEMON | LOG_INFO, "telnetd: started successfully"); |
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337 | return RTEMS_SUCCESSFUL; |
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338 | } |
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339 | |
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340 | /* utility wrapper */ |
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341 | static void |
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342 | spawned_shell(void *targ) |
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343 | { |
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344 | rtems_status_code sc; |
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345 | FILE *nstd[3]={0}; |
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346 | FILE *ostd[3]={ stdin, stdout, stderr }; |
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347 | int i=0; |
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348 | struct shell_args *arg = targ; |
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349 | telnetd_context *ctx = arg->ctx; |
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350 | bool login_failed = false; |
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351 | bool start = true; |
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352 | |
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353 | sc=rtems_libio_set_private_env(); |
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354 | |
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355 | /* newlib hack/workaround. Before we change stdin/out/err we must make |
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356 | * sure the internal data are initialized (fileno(stdout) has this sideeffect). |
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357 | * This should probably be done from RTEMS' libc support layer... |
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358 | * (T.S., newlibc-1.13; 2005/10) |
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359 | */ |
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360 | |
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361 | fileno(stdout); |
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362 | |
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363 | if (RTEMS_SUCCESSFUL != sc) { |
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364 | rtems_error(sc,"rtems_libio_set_private_env"); |
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365 | goto cleanup; |
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366 | } |
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367 | |
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368 | /* redirect stdio */ |
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369 | for (i=0; i<3; i++) { |
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370 | if ( !(nstd[i]=fopen(arg->pty.name,"r+")) ) { |
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371 | perror("unable to open stdio"); |
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372 | goto cleanup; |
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373 | } |
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374 | } |
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375 | |
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376 | stdin = nstd[0]; |
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377 | stdout = nstd[1]; |
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378 | stderr = nstd[2]; |
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379 | |
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380 | /* call their routine */ |
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381 | if (ctx->config.login_check != NULL) { |
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382 | start = rtems_shell_login_prompt( |
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383 | stdin, |
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384 | stderr, |
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385 | arg->pty.name, |
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386 | ctx->config.login_check |
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387 | ); |
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388 | login_failed = !start; |
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389 | } |
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390 | if (start) { |
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391 | ctx->config.command( arg->pty.name, ctx->config.arg); |
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392 | } |
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393 | |
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394 | stdin = ostd[0]; |
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395 | stdout = ostd[1]; |
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396 | stderr = ostd[2]; |
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397 | |
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398 | if (login_failed) { |
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399 | syslog( |
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400 | LOG_AUTHPRIV | LOG_WARNING, |
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401 | "telnetd: to many wrong passwords entered from %s", |
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402 | arg->peername |
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403 | ); |
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404 | } |
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405 | |
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406 | cleanup: |
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407 | release_a_Connection(ctx, arg->pty.name, arg->peername, nstd, i); |
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408 | free(arg); |
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409 | } |
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410 | |
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411 | struct wrap_delete_args { |
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412 | void (*t)(void *); |
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413 | void *a; |
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414 | }; |
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415 | |
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416 | static rtems_task |
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417 | wrap_delete(rtems_task_argument arg) |
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418 | { |
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419 | struct wrap_delete_args *pwa = (struct wrap_delete_args *)arg; |
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420 | register void (*t)(void *) = pwa->t; |
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421 | register void *a = pwa->a; |
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422 | |
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423 | /* free argument before calling function (which may never return if |
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424 | * they choose to delete themselves) |
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425 | */ |
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426 | free(pwa); |
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427 | t(a); |
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428 | rtems_task_exit(); |
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429 | } |
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430 | |
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431 | rtems_id |
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432 | telnetd_dflt_spawn(const char *name, unsigned int priority, unsigned int stackSize, void (*fn)(void *), void* fnarg) |
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433 | { |
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434 | rtems_status_code sc; |
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435 | rtems_id task_id = RTEMS_ID_NONE; |
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436 | char nm[4] = {'X','X','X','X' }; |
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437 | struct wrap_delete_args *pwa = malloc(sizeof(*pwa)); |
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438 | |
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439 | strncpy(nm, name, 4); |
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440 | |
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441 | if ( !pwa ) { |
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442 | perror("Telnetd: no memory\n"); |
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443 | return RTEMS_ID_NONE; |
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444 | } |
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445 | |
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446 | pwa->t = fn; |
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447 | pwa->a = fnarg; |
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448 | |
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449 | if ((sc=rtems_task_create( |
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450 | rtems_build_name(nm[0], nm[1], nm[2], nm[3]), |
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451 | (rtems_task_priority)priority, |
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452 | stackSize, |
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453 | RTEMS_DEFAULT_MODES, |
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454 | RTEMS_DEFAULT_ATTRIBUTES | RTEMS_FLOATING_POINT, |
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455 | &task_id)) || |
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456 | (sc=rtems_task_start( |
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457 | task_id, |
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458 | wrap_delete, |
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459 | (rtems_task_argument)pwa))) { |
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460 | free(pwa); |
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461 | rtems_error(sc,"Telnetd: spawning task failed"); |
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462 | return RTEMS_ID_NONE; |
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463 | } |
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464 | return task_id; |
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465 | } |
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