telnet and telnetd from Ashwini Sharma's guys.

1 files changed, 386 insertions, 0 deletions

diff --git a/toys/pending/telnet.c b/toys/pending/telnet.c
new file mode 100644
index 00000000..e0f9f6f0
--- /dev/null
+++ b/toys/pending/telnet.c
@@ -0,0 +1,386 @@
+/* telnet.c - Telnet client.
+ *
+ * Copyright 2012 Madhur Verma <mad.flexi@gmail.com>
+ * Copyright 2013 Kyungwan Han <asura321@gmail.com>
+ * Modified by Ashwini Kumar <ak.ashwini1981@gmail.com>
+ *
+ * Not in SUSv4.
+
+USE_TELNET(NEWTOY(telnet, "<1>2", TOYFLAG_BIN))
+
+config TELNET
+  bool "telnet"
+  default n
+  help
+    usage: telnet HOST [PORT]
+    Connect to telnet server
+*/
+
+#define FOR_telnet
+#include "toys.h"
+#include <arpa/telnet.h>
+#include <netinet/in.h>
+#include  <sys/poll.h>
+
+GLOBALS(
+  int port;
+  int sfd;
+  char buff[128];
+  int pbuff;
+  char iac[256];
+  int piac;
+  char *ttype;
+  struct termios def_term;
+  struct termios raw_term;
+  uint8_t term_ok;
+  uint8_t term_mode;
+  uint8_t flags;
+  unsigned win_width;
+  unsigned win_height;
+  unsigned signalno;
+)
+
+#define DATABUFSIZE 128
+#define IACBUFSIZE  256
+#define CM_TRY      0
+#define CM_ON       1
+#define CM_OFF      2
+#define UF_ECHO     0x01
+#define UF_SGA      0x02
+
+/*
+ * creates a socket of family INET/INET6 and protocol TCP and connects
+ * it to HOST at PORT.
+ * if successful then returns SOCK othrwise error
+ */
+static int xconnect_inet_tcp(char *host, int port)
+{
+  int ret;
+  struct addrinfo *info, *rp;
+  char buf[32];
+
+  rp = xzalloc(sizeof(struct addrinfo));
+  rp->ai_family = AF_UNSPEC;
+  rp->ai_socktype = SOCK_STREAM;
+  rp->ai_protocol = IPPROTO_TCP;
+  sprintf(buf, "%d", port);
+
+  ret = getaddrinfo(host, buf, rp, &info);
+  if(ret || !info) perror_exit("BAD ADDRESS: can't find : %s ", host);
+  free(rp);
+
+  for (rp = info; rp; rp = rp->ai_next) 
+    if ( (rp->ai_family == AF_INET) || (rp->ai_family == AF_INET6)) break;
+
+  if (!rp) error_exit("Invalid IP %s", host);
+
+  ret = xsocket(rp->ai_family, SOCK_STREAM, IPPROTO_TCP);
+  if(connect(ret, rp->ai_addr, rp->ai_addrlen) == -1) perror_exit("connect");
+
+  freeaddrinfo(info);
+  return ret;
+}
+
+// sets terminal mode: LINE or CHARACTER based om internal stat.
+static char const es[] = "\r\nEscape character is ";
+static void set_mode(void)
+{
+  if (TT.flags & UF_ECHO) {
+    if (TT.term_mode == CM_TRY) {
+      TT.term_mode = CM_ON;
+      printf("\r\nEntering character mode%s'^]'.\r\n", es);
+      if (TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term);
+    }
+  } else {
+    if (TT.term_mode != CM_OFF) {
+      TT.term_mode = CM_OFF;
+      printf("\r\nEntering line mode%s'^C'.\r\n", es);
+      if (TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
+    }
+  }
+}
+
+// flushes all data in IAC buff to server.
+static void flush_iac(void)
+{
+  int wlen = write(TT.sfd, TT.iac, TT.piac);
+
+  if(wlen <= 0) error_msg("IAC : send failed.");
+  TT.piac = 0;
+}
+
+// puts DATA in iac buff of length LEN and updates iac buff pointer.
+static void put_iac(int len, ...)
+{
+  va_list va; 
+
+  if(TT.piac + len >= IACBUFSIZE) flush_iac();
+  va_start(va, len);
+  for(;len > 0; TT.iac[TT.piac++] = (uint8_t)va_arg(va, int), len--);
+  va_end(va);
+}
+
+// puts string STR in iac buff and updates iac buff pointer.
+static void str_iac(char *str)
+{
+  int len = strlen(str);
+
+  if(TT.piac + len + 1 >= IACBUFSIZE) flush_iac();
+  strcpy(&TT.iac[TT.piac], str);
+  TT.piac += len+1;
+}
+
+static void handle_esc(void)
+{
+  char input;
+
+  if(TT.signalno && TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term);
+  write(1,"\r\nConsole escape. Commands are:\r\n\n"
+      " l  go to line mode\r\n"
+      " c  go to character mode\r\n"
+      " z  suspend telnet\r\n"
+      " e  exit telnet\r\n", 114);
+
+  if (read(STDIN_FILENO, &input, 1) <= 0) {
+    if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
+    exit(0);
+  }
+
+  switch (input) {
+  case 'l':
+    if (!TT.signalno) {
+      TT.term_mode = CM_TRY;
+      TT.flags &= ~(UF_ECHO | UF_SGA);
+      set_mode();
+      put_iac(6, IAC,DONT,TELOPT_ECHO,IAC,DONT, TELOPT_SGA);
+      flush_iac();
+      goto ret;
+    }
+    break;
+  case 'c':
+    if (TT.signalno) {
+      TT.term_mode = CM_TRY;
+      TT.flags |= (UF_ECHO | UF_SGA);
+      set_mode();
+      put_iac(6, IAC,DO,TELOPT_ECHO,IAC,DO,TELOPT_SGA);
+      flush_iac();
+      goto ret;
+    }
+    break;
+  case 'z':
+    if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
+    kill(0, SIGTSTP);
+    if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term);
+    break;
+  case 'e':
+    if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
+    exit(0);
+  default: break;
+  }
+
+  write(1, "continuing...\r\n", 15);
+  if (TT.signalno && TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
+
+ret:
+  TT.signalno = 0;
+}
+
+/*
+ * handles telnet SUB NEGOTIATIONS
+ * only terminal type is supported.
+ */
+static void handle_negotiations(void)
+{
+  char opt = TT.buff[TT.pbuff++];
+
+  switch(opt) {
+  case TELOPT_TTYPE:
+    opt =  TT.buff[TT.pbuff++];
+    if(opt == TELQUAL_SEND) {
+      put_iac(4, IAC,SB,TELOPT_TTYPE,TELQUAL_IS);
+      str_iac(TT.ttype);
+      put_iac(2, IAC,SE);
+    }
+    break;
+  default: break;
+  }
+}
+
+/*
+ * handles server's DO DONT WILL WONT requests.
+ * supports ECHO, SGA, TTYPE, NAWS
+ */
+static void handle_ddww(char ddww)
+{
+  char opt = TT.buff[TT.pbuff++];
+
+  switch (opt) {
+  case TELOPT_ECHO: /* ECHO */
+    if (ddww == DO) put_iac(3, IAC,WONT,TELOPT_ECHO);
+    if(ddww == DONT) break;
+    if (TT.flags & UF_ECHO) {
+        if (ddww == WILL) return;
+      } else if (ddww == WONT) return;
+    if (TT.term_mode != CM_OFF) TT.flags ^= UF_ECHO;
+    (TT.flags & UF_ECHO)? put_iac(3, IAC,DO,TELOPT_ECHO) : 
+      put_iac(3, IAC,DONT,TELOPT_ECHO);
+    set_mode();
+    printf("\r\n");
+    break;
+
+  case TELOPT_SGA: /* Supress GO Ahead */
+    if (TT.flags & UF_SGA){ if (ddww == WILL) return;
+    } else if (ddww == WONT) return;
+
+    TT.flags ^= UF_SGA;
+    (TT.flags & UF_SGA)? put_iac(3, IAC,DO,TELOPT_SGA) :
+      put_iac(3, IAC,DONT,TELOPT_SGA);
+    break;
+
+  case TELOPT_TTYPE: /* Terminal Type */
+    (TT.ttype)? put_iac(3, IAC,WILL,TELOPT_TTYPE):
+      put_iac(3, IAC,WONT,TELOPT_TTYPE);
+    break;
+
+  case TELOPT_NAWS: /* Window Size */
+    put_iac(3, IAC,WILL,TELOPT_NAWS);
+    put_iac(9, IAC,SB,TELOPT_NAWS,(TT.win_width >> 8) & 0xff,
+        TT.win_width & 0xff,(TT.win_height >> 8) & 0xff,
+        TT.win_height & 0xff,IAC,SE);
+    break;
+
+  default: /* Default behaviour is to say NO */
+    if(ddww == WILL) put_iac(3, IAC,DONT,opt);
+    if(ddww == DO) put_iac(3, IAC,WONT,opt);
+    break;
+  }
+}
+
+/*
+ * parses data which is read from server of length LEN.
+ * and passes it to console.
+ */
+static int read_server(int len)
+{
+  int i = 0;
+  char curr;
+  TT.pbuff = 0;
+
+  do {
+    curr = TT.buff[TT.pbuff++];
+    if (curr == IAC) {
+      curr = TT.buff[TT.pbuff++];
+      switch (curr) {
+      case DO:    /* FALLTHROUGH */
+      case DONT:    /* FALLTHROUGH */
+      case WILL:    /* FALLTHROUGH */
+      case WONT:
+        handle_ddww(curr);
+        break;
+      case SB:
+        handle_negotiations();
+        break;
+      case SE:
+        break;
+      default: break;
+      }
+    } else {
+      toybuf[i++] = curr;
+      if (curr == '\r') { curr = TT.buff[TT.pbuff++];
+        if (curr != '\0') TT.pbuff--;
+      }
+    }
+  } while (TT.pbuff < len);
+
+  if (i) write(STDIN_FILENO, toybuf, i);
+  return 0;
+}
+
+/*
+ * parses data which is read from console of length LEN
+ * and passes it to server.
+ */
+static void write_server(int len)
+{
+  char *c = (char*)TT.buff;
+  int i = 0;
+
+  for (; len > 0; len--, c++) {
+    if (*c == 0x1d) {
+      handle_esc();
+      return;
+    }
+    toybuf[i++] = *c;
+    if (*c == IAC) toybuf[i++] = *c; /* IAC -> IAC IAC */
+    else if (*c == '\r') toybuf[i++] = '\0'; /* CR -> CR NUL */
+  }
+  if(i) write(TT.sfd, toybuf, i);
+}
+
+/*
+ * SIGINT signal handling.
+ * only sets signalno which get handle in main loop.
+ */
+static void handle_sigint(int signo)
+{
+  TT.signalno = signo;
+}
+
+void telnet_main(void)
+{
+  int set = 1, len;
+  struct pollfd pfds[2];
+
+  TT.port = 23; //TELNET_PORT
+  TT.win_width = 80; //columns
+  TT.win_height = 24; //rows
+
+  if(toys.optc == 2) TT.port = atoi(toys.optargs[1]);
+  if(TT.port <= 0 || TT.port > 65535) 
+    error_exit("PORT can be non-zero upto 65535.");
+
+  TT.ttype = getenv("TERM");
+  if(!TT.ttype) TT.ttype = "";
+  if(strlen(TT.ttype) > IACBUFSIZE-1) TT.ttype[IACBUFSIZE - 1] = '\0';
+
+  if (!tcgetattr(0, &TT.def_term)) {
+    TT.term_ok = 1;
+    TT.raw_term = TT.def_term;
+    cfmakeraw(&TT.raw_term);
+  }
+  terminal_size(&TT.win_width, &TT.win_height);
+
+  TT.sfd = xconnect_inet_tcp(toys.optargs[0], TT.port);
+  setsockopt(TT.sfd, SOL_SOCKET, SO_REUSEADDR, &set, sizeof(set));
+  setsockopt(TT.sfd, SOL_SOCKET, SO_KEEPALIVE, &set, sizeof(set));
+
+  pfds[0].fd = STDIN_FILENO;
+  pfds[0].events = POLLIN;
+  pfds[1].fd = TT.sfd;
+  pfds[1].events = POLLIN;
+
+  TT.piac = TT.pbuff = 0;
+  TT.signalno = 0;
+  signal(SIGINT, handle_sigint);
+  while(1) {
+    if(TT.piac) flush_iac();
+    if(poll(pfds, 2, -1) < 0) {
+      (TT.signalno)?handle_esc():sleep(1);
+      continue;
+    }
+    if(pfds[0].revents) {
+      len = read(STDIN_FILENO, TT.buff, DATABUFSIZE);
+      if(len > 0) write_server(len);
+      else return;
+    }
+    if(pfds[1].revents) {
+      len = read(TT.sfd, TT.buff, DATABUFSIZE);
+      if(len > 0) read_server(len);
+      else {
+        printf("Connection closed by foreign host\r\n");
+        if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
+        exit(1);
+      }
+    }
+  }
+}