2 * Simple Telnet server code, adapted from PuTTY's own Telnet
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3 * client code for use as a Cygwin local pty proxy.
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22 #define IAC 255 /* interpret as command: */
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23 #define DONT 254 /* you are not to use option */
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24 #define DO 253 /* please, you use option */
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25 #define WONT 252 /* I won't use option */
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26 #define WILL 251 /* I will use option */
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27 #define SB 250 /* interpret as subnegotiation */
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28 #define SE 240 /* end sub negotiation */
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30 #define GA 249 /* you may reverse the line */
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31 #define EL 248 /* erase the current line */
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32 #define EC 247 /* erase the current character */
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33 #define AYT 246 /* are you there */
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34 #define AO 245 /* abort output--but let prog finish */
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35 #define IP 244 /* interrupt process--permanently */
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36 #define BREAK 243 /* break */
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37 #define DM 242 /* data mark--for connect. cleaning */
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38 #define NOP 241 /* nop */
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39 #define EOR 239 /* end of record (transparent mode) */
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40 #define ABORT 238 /* Abort process */
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41 #define SUSP 237 /* Suspend process */
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42 #define xEOF 236 /* End of file: EOF is already used... */
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44 #define TELOPTS(X) \
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45 X(BINARY, 0) /* 8-bit data path */ \
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46 X(ECHO, 1) /* echo */ \
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47 X(RCP, 2) /* prepare to reconnect */ \
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48 X(SGA, 3) /* suppress go ahead */ \
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49 X(NAMS, 4) /* approximate message size */ \
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50 X(STATUS, 5) /* give status */ \
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51 X(TM, 6) /* timing mark */ \
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52 X(RCTE, 7) /* remote controlled transmission and echo */ \
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53 X(NAOL, 8) /* negotiate about output line width */ \
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54 X(NAOP, 9) /* negotiate about output page size */ \
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55 X(NAOCRD, 10) /* negotiate about CR disposition */ \
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56 X(NAOHTS, 11) /* negotiate about horizontal tabstops */ \
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57 X(NAOHTD, 12) /* negotiate about horizontal tab disposition */ \
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58 X(NAOFFD, 13) /* negotiate about formfeed disposition */ \
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59 X(NAOVTS, 14) /* negotiate about vertical tab stops */ \
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60 X(NAOVTD, 15) /* negotiate about vertical tab disposition */ \
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61 X(NAOLFD, 16) /* negotiate about output LF disposition */ \
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62 X(XASCII, 17) /* extended ascic character set */ \
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63 X(LOGOUT, 18) /* force logout */ \
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64 X(BM, 19) /* byte macro */ \
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65 X(DET, 20) /* data entry terminal */ \
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66 X(SUPDUP, 21) /* supdup protocol */ \
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67 X(SUPDUPOUTPUT, 22) /* supdup output */ \
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68 X(SNDLOC, 23) /* send location */ \
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69 X(TTYPE, 24) /* terminal type */ \
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70 X(EOR, 25) /* end or record */ \
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71 X(TUID, 26) /* TACACS user identification */ \
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72 X(OUTMRK, 27) /* output marking */ \
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73 X(TTYLOC, 28) /* terminal location number */ \
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74 X(3270REGIME, 29) /* 3270 regime */ \
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75 X(X3PAD, 30) /* X.3 PAD */ \
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76 X(NAWS, 31) /* window size */ \
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77 X(TSPEED, 32) /* terminal speed */ \
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78 X(LFLOW, 33) /* remote flow control */ \
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79 X(LINEMODE, 34) /* Linemode option */ \
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80 X(XDISPLOC, 35) /* X Display Location */ \
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81 X(OLD_ENVIRON, 36) /* Old - Environment variables */ \
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82 X(AUTHENTICATION, 37) /* Authenticate */ \
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83 X(ENCRYPT, 38) /* Encryption option */ \
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84 X(NEW_ENVIRON, 39) /* New - Environment variables */ \
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85 X(TN3270E, 40) /* TN3270 enhancements */ \
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87 X(CHARSET, 42) /* Character set */ \
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88 X(RSP, 43) /* Remote serial port */ \
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89 X(COM_PORT_OPTION, 44) /* Com port control */ \
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90 X(SLE, 45) /* Suppress local echo */ \
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91 X(STARTTLS, 46) /* Start TLS */ \
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92 X(KERMIT, 47) /* Automatic Kermit file transfer */ \
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95 X(PRAGMA_LOGON, 138) \
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96 X(SSPI_LOGON, 139) \
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97 X(PRAGMA_HEARTBEAT, 140) \
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98 X(EXOPL, 255) /* extended-options-list */
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100 #define telnet_enum(x,y) TELOPT_##x = y,
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101 enum { TELOPTS(telnet_enum) dummy=0 };
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104 #define TELQUAL_IS 0 /* option is... */
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105 #define TELQUAL_SEND 1 /* send option */
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106 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
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108 #define BSD_VALUE 0
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110 #define RFC_VALUE 1
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116 #define iswritable(x) ( (x) != IAC && (x) != CR )
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118 static char *telopt(int opt)
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120 #define telnet_str(x,y) case TELOPT_##x: return #x;
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122 TELOPTS(telnet_str)
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124 return "<unknown>";
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129 static void telnet_size(void *handle, int width, int height);
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132 int send; /* what we initially send */
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133 int nsend; /* -ve send if requested to stop it */
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134 int ack, nak; /* +ve and -ve acknowledgements */
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135 int option; /* the option code */
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136 int index; /* index into telnet->opt_states[] */
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138 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
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156 static const struct Opt o_naws =
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157 { DO, DONT, WILL, WONT, TELOPT_NAWS, OPTINDEX_NAWS, REQUESTED };
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158 static const struct Opt o_ttype =
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159 { DO, DONT, WILL, WONT, TELOPT_TTYPE, OPTINDEX_TTYPE, REQUESTED };
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160 static const struct Opt o_oenv =
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161 { DO, DONT, WILL, WONT, TELOPT_OLD_ENVIRON, OPTINDEX_OENV, INACTIVE };
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162 static const struct Opt o_nenv =
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163 { DO, DONT, WILL, WONT, TELOPT_NEW_ENVIRON, OPTINDEX_NENV, REQUESTED };
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164 static const struct Opt o_echo =
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165 { WILL, WONT, DO, DONT, TELOPT_ECHO, OPTINDEX_ECHO, REQUESTED };
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166 static const struct Opt o_they_sga =
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167 { DO, DONT, WILL, WONT, TELOPT_SGA, OPTINDEX_WE_SGA, REQUESTED };
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168 static const struct Opt o_we_sga =
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169 { WILL, WONT, DO, DONT, TELOPT_SGA, OPTINDEX_THEY_SGA, REQUESTED };
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171 static const struct Opt *const opts[] = {
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172 &o_echo, &o_we_sga, &o_they_sga, &o_naws, &o_ttype, &o_oenv, &o_nenv, NULL
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175 struct telnet_tag {
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176 int opt_states[NUM_OPTS];
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178 int sb_opt, sb_len;
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179 unsigned char *sb_buf;
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183 TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
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184 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
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187 sel_wfd *net, *pty;
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190 * Options we must finish processing before launching the shell
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192 int old_environ_done, new_environ_done, ttype_done;
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195 * Ready to start shell?
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199 struct shell_data shdata;
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202 #define TELNET_MAX_BACKLOG 4096
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204 #define SB_DELTA 1024
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206 static void send_opt(Telnet telnet, int cmd, int option)
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208 unsigned char b[3];
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213 sel_write(telnet->net, (char *)b, 3);
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216 static void deactivate_option(Telnet telnet, const struct Opt *o)
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218 if (telnet->opt_states[o->index] == REQUESTED ||
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219 telnet->opt_states[o->index] == ACTIVE)
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220 send_opt(telnet, o->nsend, o->option);
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221 telnet->opt_states[o->index] = REALLY_INACTIVE;
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225 * Generate side effects of enabling or disabling an option.
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227 static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
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231 static void activate_option(Telnet telnet, const struct Opt *o)
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233 if (o->option == TELOPT_NEW_ENVIRON ||
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234 o->option == TELOPT_OLD_ENVIRON ||
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235 o->option == TELOPT_TTYPE) {
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239 buf[2] = o->option;
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240 buf[3] = TELQUAL_SEND;
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243 sel_write(telnet->net, buf, 6);
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245 option_side_effects(telnet, o, 1);
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248 static void done_option(Telnet telnet, int option)
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250 if (option == TELOPT_OLD_ENVIRON)
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251 telnet->old_environ_done = 1;
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252 else if (option == TELOPT_NEW_ENVIRON)
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253 telnet->new_environ_done = 1;
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254 else if (option == TELOPT_TTYPE)
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255 telnet->ttype_done = 1;
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257 if (telnet->old_environ_done && telnet->new_environ_done &&
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258 telnet->ttype_done) {
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259 telnet->shell_ok = 1;
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263 static void refused_option(Telnet telnet, const struct Opt *o)
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265 done_option(telnet, o->option);
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266 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
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267 telnet->opt_states[o_oenv.index] == INACTIVE) {
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268 send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
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269 telnet->opt_states[o_oenv.index] = REQUESTED;
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270 telnet->old_environ_done = 0;
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272 option_side_effects(telnet, o, 0);
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275 static void proc_rec_opt(Telnet telnet, int cmd, int option)
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277 const struct Opt *const *o;
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279 for (o = opts; *o; o++) {
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280 if ((*o)->option == option && (*o)->ack == cmd) {
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281 switch (telnet->opt_states[(*o)->index]) {
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283 telnet->opt_states[(*o)->index] = ACTIVE;
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284 activate_option(telnet, *o);
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289 telnet->opt_states[(*o)->index] = ACTIVE;
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290 send_opt(telnet, (*o)->send, option);
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291 activate_option(telnet, *o);
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293 case REALLY_INACTIVE:
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294 send_opt(telnet, (*o)->nsend, option);
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298 } else if ((*o)->option == option && (*o)->nak == cmd) {
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299 switch (telnet->opt_states[(*o)->index]) {
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301 telnet->opt_states[(*o)->index] = INACTIVE;
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302 refused_option(telnet, *o);
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305 telnet->opt_states[(*o)->index] = INACTIVE;
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306 send_opt(telnet, (*o)->nsend, option);
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307 option_side_effects(telnet, *o, 0);
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310 case REALLY_INACTIVE:
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317 * If we reach here, the option was one we weren't prepared to
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318 * cope with. If the request was positive (WILL or DO), we send
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319 * a negative ack to indicate refusal. If the request was
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320 * negative (WONT / DONT), we must do nothing.
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322 if (cmd == WILL || cmd == DO)
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323 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
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326 static void process_subneg(Telnet telnet)
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328 unsigned char b[2048], *p, *q;
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332 switch (telnet->sb_opt) {
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333 case TELOPT_OLD_ENVIRON:
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334 case TELOPT_NEW_ENVIRON:
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335 if (telnet->sb_buf[0] == TELQUAL_IS) {
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336 if (telnet->sb_opt == TELOPT_NEW_ENVIRON) {
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340 if (telnet->sb_len > 1 && !(telnet->sb_buf[0] &~ 1)) {
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341 var = telnet->sb_buf[0];
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342 value = BSD_VAR ^ BSD_VALUE ^ var;
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350 while (n < telnet->sb_len && telnet->sb_buf[n] == var) {
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351 int varpos, varlen, valpos, vallen;
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355 while (n < telnet->sb_len && telnet->sb_buf[n] != value)
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357 if (n == telnet->sb_len)
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359 varlen = n - varpos;
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361 while (n < telnet->sb_len && telnet->sb_buf[n] != var)
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363 vallen = n - valpos;
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365 result = snewn(varlen + vallen + 2, char);
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366 sprintf(result, "%.*s=%.*s",
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367 varlen, telnet->sb_buf+varpos,
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368 vallen, telnet->sb_buf+valpos);
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369 if (telnet->shdata.nenvvars >= telnet->envvarsize) {
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370 telnet->envvarsize = telnet->shdata.nenvvars * 3 / 2 + 16;
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371 telnet->shdata.envvars = sresize(telnet->shdata.envvars,
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372 telnet->envvarsize, char *);
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374 telnet->shdata.envvars[telnet->shdata.nenvvars++] = result;
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376 done_option(telnet, telnet->sb_opt);
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379 if (telnet->sb_len >= 1 && telnet->sb_buf[0] == TELQUAL_IS) {
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380 telnet->shdata.termtype = snewn(5 + telnet->sb_len, char);
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381 strcpy(telnet->shdata.termtype, "TERM=");
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382 for (n = 0; n < telnet->sb_len-1; n++) {
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383 char c = telnet->sb_buf[n+1];
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384 if (c >= 'A' && c <= 'Z')
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386 telnet->shdata.termtype[n+5] = c;
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388 telnet->shdata.termtype[telnet->sb_len+5-1] = '\0';
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390 done_option(telnet, telnet->sb_opt);
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393 if (telnet->sb_len == 4) {
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395 w = (unsigned char)telnet->sb_buf[0];
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396 w = (w << 8) | (unsigned char)telnet->sb_buf[1];
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397 h = (unsigned char)telnet->sb_buf[2];
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398 h = (h << 8) | (unsigned char)telnet->sb_buf[3];
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405 void telnet_from_net(Telnet telnet, char *buf, int len)
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408 int c = (unsigned char) *buf++;
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410 switch (telnet->state) {
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414 * PuTTY sends Telnet's new line sequence (CR LF on
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415 * the wire) in response to the return key. We must
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416 * therefore treat that as equivalent to CR NUL, and
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417 * send CR to the pty.
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419 if ((c == NUL || c == '\n') && telnet->state == SEENCR)
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420 telnet->state = TOP_LEVEL;
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422 telnet->state = SEENIAC;
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425 sel_write(telnet->pty, &cc, 1);
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427 telnet->state = SEENCR;
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432 telnet->state = SEENDO;
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433 else if (c == DONT)
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434 telnet->state = SEENDONT;
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435 else if (c == WILL)
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436 telnet->state = SEENWILL;
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437 else if (c == WONT)
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438 telnet->state = SEENWONT;
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440 telnet->state = SEENSB;
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442 telnet->state = TOP_LEVEL;
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444 /* ignore everything else; print it if it's IAC */
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447 sel_write(telnet->pty, &cc, 1);
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449 telnet->state = TOP_LEVEL;
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453 proc_rec_opt(telnet, WILL, c);
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454 telnet->state = TOP_LEVEL;
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457 proc_rec_opt(telnet, WONT, c);
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458 telnet->state = TOP_LEVEL;
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461 proc_rec_opt(telnet, DO, c);
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462 telnet->state = TOP_LEVEL;
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465 proc_rec_opt(telnet, DONT, c);
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466 telnet->state = TOP_LEVEL;
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469 telnet->sb_opt = c;
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470 telnet->sb_len = 0;
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471 telnet->state = SUBNEGOT;
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475 telnet->state = SUBNEG_IAC;
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478 if (telnet->sb_len >= telnet->sb_size) {
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479 telnet->sb_size += SB_DELTA;
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480 telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
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483 telnet->sb_buf[telnet->sb_len++] = c;
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484 telnet->state = SUBNEGOT; /* in case we came here by goto */
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489 goto subneg_addchar; /* yes, it's a hack, I know, but... */
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491 process_subneg(telnet);
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492 telnet->state = TOP_LEVEL;
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499 Telnet telnet_new(sel_wfd *net, sel_wfd *pty)
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503 telnet = snew(struct telnet_tag);
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504 telnet->sb_buf = NULL;
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505 telnet->sb_size = 0;
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506 telnet->state = TOP_LEVEL;
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509 telnet->shdata.envvars = NULL;
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510 telnet->shdata.nenvvars = telnet->envvarsize = 0;
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511 telnet->shdata.termtype = NULL;
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514 * Initialise option states.
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517 const struct Opt *const *o;
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519 for (o = opts; *o; o++) {
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520 telnet->opt_states[(*o)->index] = (*o)->initial_state;
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521 if (telnet->opt_states[(*o)->index] == REQUESTED)
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522 send_opt(telnet, (*o)->send, (*o)->option);
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526 telnet->old_environ_done = 1; /* initially don't want to bother */
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527 telnet->new_environ_done = 0;
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528 telnet->ttype_done = 0;
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529 telnet->shell_ok = 0;
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534 void telnet_free(Telnet telnet)
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536 sfree(telnet->sb_buf);
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540 void telnet_from_pty(Telnet telnet, char *buf, int len)
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542 unsigned char *p, *end;
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543 static const unsigned char iac[2] = { IAC, IAC };
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544 static const unsigned char cr[2] = { CR, NUL };
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546 static const unsigned char nl[2] = { CR, LF };
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549 p = (unsigned char *)buf;
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550 end = (unsigned char *)(buf + len);
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552 unsigned char *q = p;
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554 while (p < end && iswritable(*p))
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556 sel_write(telnet->net, (char *)q, p - q);
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558 while (p < end && !iswritable(*p)) {
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559 sel_write(telnet->net, (char *)(*p == IAC ? iac : cr), 2);
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565 int telnet_shell_ok(Telnet telnet, struct shell_data *shdata)
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567 if (telnet->shell_ok)
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568 *shdata = telnet->shdata; /* structure copy */
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569 return telnet->shell_ok;
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