Class: Net::Telnet

Inherits:

Object

Object
Net::Telnet

show all

Defined in:: lib/net/telnet.rb,
lib/net/telnet/version.rb

Overview

Net::Telnet

Provides telnet client functionality.

This class also has, through delegation, all the methods of a socket object (by default, a TCPSocket, but can be set by the Proxy option to new()). This provides methods such as close() to end the session and sysread() to read data directly from the host, instead of via the waitfor() mechanism. Note that if you do use sysread() directly when in telnet mode, you should probably pass the output through preprocess() to extract telnet command sequences.

Overview

The telnet protocol allows a client to login remotely to a user account on a server and execute commands via a shell. The equivalent is done by creating a Net::Telnet class with the Host option set to your host, calling #login() with your user and password, issuing one or more #cmd() calls, and then calling #close() to end the session. The #waitfor(), #print(), #puts(), and #write() methods, which #cmd() is implemented on top of, are only needed if you are doing something more complicated.

A Net::Telnet object can also be used to connect to non-telnet services, such as SMTP or HTTP. In this case, you normally want to provide the Port option to specify the port to connect to, and set the Telnetmode option to false to prevent the client from attempting to interpret telnet command sequences. Generally, #login() will not work with other protocols, and you have to handle authentication yourself.

For some protocols, it will be possible to specify the Prompt option once when you create the Telnet object and use #cmd() calls; for others, you will have to specify the response sequence to look for as the Match option to every #cmd() call, or call #puts() and #waitfor() directly; for yet others, you will have to use #sysread() instead of #waitfor() and parse server responses yourself.

It is worth noting that when you create a new Net::Telnet object, you can supply a proxy IO channel via the Proxy option. This can be used to attach the Telnet object to other Telnet objects, to already open sockets, or to any read-write IO object. This can be useful, for instance, for setting up a test fixture for unit testing.

Examples

Log in and send a command, echoing all output to stdout

localhost = Net::Telnet::new("Host" => "localhost",
                             "Timeout" => 10,
                             "Prompt" => /[$%#>] \z/n)
localhost.login("username", "password") { |c| print c }
localhost.cmd("command") { |c| print c }
localhost.close

Check a POP server to see if you have mail

pop = Net::Telnet::new("Host" => "your_destination_host_here",
                       "Port" => 110,
                       "Telnetmode" => false,
                       "Prompt" => /^\+OK/n)
pop.cmd("user " + "your_username_here") { |c| print c }
pop.cmd("pass " + "your_password_here") { |c| print c }
pop.cmd("list") { |c| print c }

References

There are a large number of RFCs relevant to the Telnet protocol. RFCs 854-861 define the base protocol. For a complete listing of relevant RFCs, see www.omnifarious.org/~hopper/technical/telnet-rfc.html

Constant Summary collapse

IAC = :stopdoc:

255.chr

DONT = “377” # “xff” # interpret as command

254.chr

DO = “376” # “xfe” # you are not to use option

253.chr

WONT = “375” # “xfd” # please, you use option

252.chr

WILL = “374” # “xfc” # I won’t use option

251.chr

SB = “373” # “xfb” # I will use option

250.chr

GA = “372” # “xfa” # interpret as subnegotiation

249.chr

EL = “371” # “xf9” # you may reverse the line

248.chr

EC = “370” # “xf8” # erase the current line

247.chr

AYT = “367” # “xf7” # erase the current character

246.chr

AO = “366” # “xf6” # are you there

245.chr

IP = “365” # “xf5” # abort output–but let prog finish

244.chr

BREAK = “364” # “xf4” # interrupt process–permanently

243.chr

DM = “363” # “xf3” # break

242.chr

NOP = “362” # “xf2” # data mark–for connect. cleaning

241.chr

SE = “361” # “xf1” # nop

240.chr

EOR = “360” # “xf0” # end sub negotiation

239.chr

ABORT = “357” # “xef” # end of record (transparent mode)

238.chr

SUSP = “356” # “xee” # Abort process

237.chr

EOF = “355” # “xed” # Suspend process

236.chr

SYNCH = “354” # “xec” # End of file

242.chr

OPT_BINARY = “362” # “xf2” # for telfunc calls

0.chr

OPT_ECHO = “000” # “x00” # Binary Transmission

1.chr

OPT_RCP = “001” # “x01” # Echo

2.chr

OPT_SGA = “002” # “x02” # Reconnection

3.chr

OPT_NAMS = “003” # “x03” # Suppress Go Ahead

4.chr

OPT_STATUS = “004” # “x04” # Approx Message Size Negotiation

5.chr

OPT_TM = “005” # “x05” # Status

6.chr

OPT_RCTE = “006” # “x06” # Timing Mark

7.chr

OPT_NAOL = “a” # “x07” # Remote Controlled Trans and Echo

8.chr

OPT_NAOP = “010” # “x08” # Output Line Width

9.chr

OPT_NAOCRD = “t” # “x09” # Output Page Size

10.chr

OPT_NAOHTS = “n” # “x0a” # Output Carriage-Return Disposition

11.chr

OPT_NAOHTD = “v” # “x0b” # Output Horizontal Tab Stops

12.chr

OPT_NAOFFD = “f” # “x0c” # Output Horizontal Tab Disposition

13.chr

OPT_NAOVTS = “r” # “x0d” # Output Formfeed Disposition

14.chr

OPT_NAOVTD = “016” # “x0e” # Output Vertical Tabstops

15.chr

OPT_NAOLFD = “017” # “x0f” # Output Vertical Tab Disposition

16.chr

OPT_XASCII = “020” # “x10” # Output Linefeed Disposition

17.chr

OPT_LOGOUT = “021” # “x11” # Extended ASCII

18.chr

OPT_BM = “022” # “x12” # Logout

19.chr

OPT_DET = “023” # “x13” # Byte Macro

20.chr

OPT_SUPDUP = “024” # “x14” # Data Entry Terminal

21.chr

OPT_SUPDUPOUTPUT = “025” # “x15” # SUPDUP

22.chr

OPT_SNDLOC = “026” # “x16” # SUPDUP Output

23.chr

OPT_TTYPE = “027” # “x17” # Send Location

24.chr

OPT_EOR = “030” # “x18” # Terminal Type

25.chr

OPT_TUID = “031” # “x19” # End of Record

26.chr

OPT_OUTMRK = “032” # “x1a” # TACACS User Identification

27.chr

OPT_TTYLOC = “e” # “x1b” # Output Marking

28.chr

OPT_3270REGIME = “034” # “x1c” # Terminal Location Number

29.chr

OPT_X3PAD = “035” # “x1d” # Telnet 3270 Regime

30.chr

OPT_NAWS = “036” # “x1e” # X.3 PAD

31.chr

OPT_TSPEED = “037” # “x1f” # Negotiate About Window Size

32.chr

OPT_LFLOW = “ ” # “x20” # Terminal Speed

33.chr

OPT_LINEMODE = “!” # “x21” # Remote Flow Control

34.chr

OPT_XDISPLOC = “"” # “x22” # Linemode

35.chr

OPT_OLD_ENVIRON = “#” # “x23” # X Display Location

36.chr

OPT_AUTHENTICATION = “$” # “x24” # Environment Option

37.chr

OPT_ENCRYPT = “%” # “x25” # Authentication Option

38.chr

OPT_NEW_ENVIRON = “&” # “x26” # Encryption Option

39.chr

OPT_EXOPL = “‘” # “x27” # New Environment Option

255.chr

NULL = “377” # “xff” # Extended-Options-List

"\000"

CR =

"\015"

LF =

"\012"

EOL =

CR + LF

REVISION =

'$Id$'

VERSION =

"0.2.0"

Instance Attribute Summary collapse

#sock ⇒ Object readonly

The socket the Telnet object is using.

Instance Method Summary collapse

#binmode(mode = nil) ⇒ Object

Turn newline conversion on (mode == false) or off (mode == true), or return the current value (mode is not specified).
#binmode=(mode) ⇒ Object

Turn newline conversion on (false) or off (true).
#close ⇒ Object

Closes the connection.
#cmd(options) ⇒ Object

Send a command to the host.
#initialize(options) ⇒ Telnet constructor

Creates a new Net::Telnet object.
#login(options, password = nil) ⇒ Object

Login to the host with a given username and password.
#preprocess(string) ⇒ Object

Preprocess received data from the host.
#print(string) ⇒ Object

Sends a string to the host.
#puts(string) ⇒ Object

Sends a string to the host.
#telnetmode(mode = nil) ⇒ Object

Set telnet command interpretation on (mode == true) or off (mode == false), or return the current value (mode not provided).
#telnetmode=(mode) ⇒ Object

Turn telnet command interpretation on (true) or off (false).
#waitfor(options) ⇒ Object

Read data from the host until a certain sequence is matched.
#write(string) ⇒ Object

Write string to the host.

Constructor Details

#initialize(options) ⇒ `Telnet`

Creates a new Net::Telnet object.

Attempts to connect to the host (unless the Proxy option is provided: see below). If a block is provided, it is yielded status messages on the attempt to connect to the server, of the form:

Trying localhost...
Connected to localhost.

options is a hash of options. The following example lists all options and their default values.

host = Net::Telnet::new(
         "Host"       => "localhost",  # default: "localhost"
         "Port"       => 23,           # default: 23
         "Binmode"    => false,        # default: false
         "Output_log" => "output_log", # default: nil (no output)
         "Dump_log"   => "dump_log",   # default: nil (no output)
         "Prompt"     => /[$%#>] \z/n, # default: /[$%#>] \z/n
         "Telnetmode" => true,         # default: true
         "Timeout"    => 10,           # default: 10
           # if ignore timeout then set "Timeout" to false.
         "Waittime"   => 0,            # default: 0
         "Proxy"      => proxy         # default: nil
                         # proxy is Net::Telnet or IO object
       )

The options have the following meanings:

Host: the hostname or IP address of the host to connect to, as a String. Defaults to “localhost”.
Port: the port to connect to. Defaults to 23.
Binmode: if false (the default), newline substitution is performed. Outgoing LF is converted to CRLF, and incoming CRLF is converted to LF. If true, this substitution is not performed. This value can also be set with the #binmode() method. The outgoing conversion only applies to the #puts() and #print() methods, not the #write() method. The precise nature of the newline conversion is also affected by the telnet options SGA and BIN.
Output_log: the name of the file to write connection status messages and all received traffic to. In the case of a proper Telnet session, this will include the client input as echoed by the host; otherwise, it only includes server responses. Output is appended verbatim to this file. By default, no output log is kept.
Dump_log: as for Output_log, except that output is written in hexdump format (16 bytes per line as hex pairs, followed by their printable equivalent), with connection status messages preceded by ‘#’, sent traffic preceded by ‘>’, and received traffic preceded by ‘<’. By default, not dump log is kept.
Prompt: a regular expression matching the host’s command-line prompt sequence. This is needed by the Telnet class to determine when the output from a command has finished and the host is ready to receive a new command. By default, this regular expression is /[$%#>] z/n.
Telnetmode: a boolean value, true by default. In telnet mode, traffic received from the host is parsed for special command sequences, and these sequences are escaped in outgoing traffic sent using #puts() or #print() (but not #write()). If you are using the Net::Telnet object to connect to a non-telnet service (such as SMTP or POP), this should be set to “false” to prevent undesired data corruption. This value can also be set by the #telnetmode() method.
Timeout: the number of seconds to wait before timing out both the initial attempt to connect to host (in this constructor), which raises a Net::OpenTimeout, and all attempts to read data from the host, which raises a Net::ReadTimeout (in #waitfor(), #cmd(), and #login()). The default value is 10 seconds. You can disable the timeout by setting this value to false. In this case, the connect attempt will eventually timeout on the underlying connect(2) socket call with an Errno::ETIMEDOUT error (but generally only after a few minutes), but other attempts to read data from the host will hang indefinitely if no data is forthcoming.
Waittime: the amount of time to wait after seeing what looks like a prompt (that is, received data that matches the Prompt option regular expression) to see if more data arrives. If more data does arrive in this time, Net::Telnet assumes that what it saw was not really a prompt. This is to try to avoid false matches, but it can also lead to missing real prompts (if, for instance, a background process writes to the terminal soon after the prompt is displayed). By default, set to 0, meaning not to wait for more data.
Proxy: a proxy object to used instead of opening a direct connection to the host. Must be either another Net::Telnet object or an IO object. If it is another Net::Telnet object, this instance will use that one’s socket for communication. If an IO object, it is used directly for communication. Any other kind of object will cause an error to be raised.

# File 'lib/net/telnet.rb', line 273

def initialize(options) # :yield: mesg
  @options = options
  @options["Host"]       = "localhost"   unless @options.has_key?("Host")
  @options["Port"]       = 23            unless @options.has_key?("Port")
  @options["Prompt"]     = /[$%#>] \z/n  unless @options.has_key?("Prompt")
  @options["Timeout"]    = 10            unless @options.has_key?("Timeout")
  @options["Waittime"]   = 0             unless @options.has_key?("Waittime")
  unless @options.has_key?("Binmode")
    @options["Binmode"]    = false
  else
    unless (true == @options["Binmode"] or false == @options["Binmode"])
      raise ArgumentError, "Binmode option must be true or false"
    end
  end

  unless @options.has_key?("Telnetmode")
    @options["Telnetmode"] = true
  else
    unless (true == @options["Telnetmode"] or false == @options["Telnetmode"])
      raise ArgumentError, "Telnetmode option must be true or false"
    end
  end

  @telnet_option = { "SGA" => false, "BINARY" => false }

  if @options.has_key?("Output_log")
    @log = File.open(@options["Output_log"], 'a+')
    @log.sync = true
    @log.binmode
  end

  if @options.has_key?("Dump_log")
    @dumplog = File.open(@options["Dump_log"], 'a+')
    @dumplog.sync = true
    @dumplog.binmode
    def @dumplog.log_dump(dir, x)  # :nodoc:
      len = x.length
      addr = 0
      offset = 0
      while 0 < len
        if len < 16
          line = x[offset, len]
        else
          line = x[offset, 16]
        end
        hexvals = line.unpack('H*')[0]
        hexvals += ' ' * (32 - hexvals.length)
        hexvals = format("%s %s %s %s  " * 4, *hexvals.unpack('a2' * 16))
        line = line.gsub(/[\000-\037\177-\377]/n, '.')
        printf "%s 0x%5.5x: %s%s\n", dir, addr, hexvals, line
        addr += 16
        offset += 16
        len -= 16
      end
      print "\n"
    end
  end

  if @options.has_key?("Proxy")
    if @options["Proxy"].kind_of?(Net::Telnet)
      @sock = @options["Proxy"].sock
    elsif @options["Proxy"].kind_of?(IO)
      @sock = @options["Proxy"]
    else
      raise "Error: Proxy must be an instance of Net::Telnet or IO."
    end
  else
    message = "Trying " + @options["Host"] + "...\n"
    yield(message) if block_given?
    @log.write(message) if @options.has_key?("Output_log")
    @dumplog.log_dump('#', message) if @options.has_key?("Dump_log")

    begin
      if @options["Timeout"] == false
        @sock = TCPSocket.open(@options["Host"], @options["Port"])
      else
        Timeout.timeout(@options["Timeout"], Net::OpenTimeout) do
          @sock = TCPSocket.open(@options["Host"], @options["Port"])
        end
      end
    rescue Net::OpenTimeout
      raise Net::OpenTimeout, "timed out while opening a connection to the host"
    rescue
      @log.write($ERROR_INFO.to_s + "\n") if @options.has_key?("Output_log")
      @dumplog.log_dump('#', $ERROR_INFO.to_s + "\n") if @options.has_key?("Dump_log")
      raise
    end
    @sock.sync = true
    @sock.binmode

    message = "Connected to " + @options["Host"] + ".\n"
    yield(message) if block_given?
    @log.write(message) if @options.has_key?("Output_log")
    @dumplog.log_dump('#', message) if @options.has_key?("Dump_log")
  end

end

Instance Attribute Details

#sock ⇒ `Object` (readonly)

The socket the Telnet object is using. Note that this object becomes a delegate of the Telnet object, so normally you invoke its methods directly on the Telnet object.



374
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376

# File 'lib/net/telnet.rb', line 374

def sock
  @sock
end

Instance Method Details

#binmode(mode = nil) ⇒ `Object`

Turn newline conversion on (mode == false) or off (mode == true), or return the current value (mode is not specified).

# File 'lib/net/telnet.rb', line 405

def binmode(mode = nil)
  case mode
  when nil
    @options["Binmode"]
  when true, false
    @options["Binmode"] = mode
  else
    raise ArgumentError, "argument must be true or false"
  end
end

#binmode=(mode) ⇒ `Object`

Turn newline conversion on (false) or off (true).

# File 'lib/net/telnet.rb', line 417

def binmode=(mode)
  if (true == mode or false == mode)
    @options["Binmode"] = mode
  else
    raise ArgumentError, "argument must be true or false"
  end
end

#close ⇒ `Object`

Closes the connection



757
758
759

# File 'lib/net/telnet.rb', line 757

def close
  @sock.close
end

#cmd(options) ⇒ `Object`

Send a command to the host.

More exactly, sends a string to the host, and reads in all received data until is sees the prompt or other matched sequence.

If a block is given, the received data will be yielded to it as it is read in. Whether a block is given or not, the received data will be return as a string. Note that the received data includes the prompt and in most cases the host’s echo of our command.

options is either a String, specified the string or command to send to the host; or it is a hash of options. If a hash, the following options can be specified:

String: the command or other string to send to the host.
Match: a regular expression, the sequence to look for in the received data before returning. If not specified, the Prompt option value specified when this instance was created will be used, or, failing that, the default prompt of /[$%#>] z/n.
Timeout: the seconds to wait for data from the host before raising a Timeout error. If not specified, the Timeout option value specified when this instance was created will be used, or, failing that, the default value of 10 seconds.

The command or other string will have the newline sequence appended to it.

# File 'lib/net/telnet.rb', line 678

def cmd(options) # :yield: recvdata
  match    = @options["Prompt"]
  time_out = @options["Timeout"]
  fail_eof = @options["FailEOF"]

  if options.kind_of?(Hash)
    string   = options["String"]
    match    = options["Match"]   if options.has_key?("Match")
    time_out = options["Timeout"] if options.has_key?("Timeout")
    fail_eof = options["FailEOF"] if options.has_key?("FailEOF")
  else
    string = options
  end

  self.puts(string)
  if block_given?
    waitfor({"Prompt" => match, "Timeout" => time_out, "FailEOF" => fail_eof}){|c| yield c }
  else
    waitfor({"Prompt" => match, "Timeout" => time_out, "FailEOF" => fail_eof})
  end
end

The username and password can either be provided as two string arguments in that order, or as a hash with keys “Name” and “Password”.

This method looks for the strings “login” and “Password” from the host to determine when to send the username and password. If the login sequence does not follow this pattern (for instance, you are connecting to a service other than telnet), you will need to handle login yourself.

The password can be omitted, either by only provided one String argument, which will be used as the username, or by providing a has that has no “Password” key. In this case, the method will not look for the “Password:” prompt; if it is sent, it will have to be dealt with by later calls.

The method returns all data received during the login process from the host, including the echoed username but not the password (which the host should not echo). If a block is passed in, this received data is also yielded to the block as it is received.

# File 'lib/net/telnet.rb', line 722

def login(options, password = nil) # :yield: recvdata
  login_prompt = /[Ll]ogin[: ]*\z/n
  password_prompt = /[Pp]ass(?:word|phrase)[: ]*\z/n
  if options.kind_of?(Hash)
    username = options["Name"]
    password = options["Password"]
    login_prompt = options["LoginPrompt"] if options["LoginPrompt"]
    password_prompt = options["PasswordPrompt"] if options["PasswordPrompt"]
  else
    username = options
  end

  if block_given?
    line = waitfor(login_prompt){|c| yield c }
    if password
      line += cmd({"String" => username,
                   "Match" => password_prompt}){|c| yield c }
      line += cmd(password){|c| yield c }
    else
      line += cmd(username){|c| yield c }
    end
  else
    line = waitfor(login_prompt)
    if password
      line += cmd({"String" => username,
                   "Match" => password_prompt})
      line += cmd(password)
    else
      line += cmd(username)
    end
  end
  line
end

#preprocess(string) ⇒ `Object`

Preprocess received data from the host.

Performs newline conversion and detects telnet command sequences. Called automatically by #waitfor(). You should only use this method yourself if you have read input directly using sysread() or similar, and even then only if in telnet mode.

# File 'lib/net/telnet.rb', line 431

def preprocess(string)
  # combine CR+NULL into CR
  string = string.gsub(/#{CR}#{NULL}/no, CR) if @options["Telnetmode"]

  # combine EOL into "\n"
  string = string.gsub(/#{EOL}/no, "\n") unless @options["Binmode"]

  # remove NULL
  string = string.gsub(/#{NULL}/no, '') unless @options["Binmode"]

  string.gsub(/#{IAC}(
               [#{IAC}#{AO}#{AYT}#{DM}#{IP}#{NOP}]|
               [#{DO}#{DONT}#{WILL}#{WONT}]
                 [#{OPT_BINARY}-#{OPT_NEW_ENVIRON}#{OPT_EXOPL}]|
               #{SB}[^#{IAC}]*#{IAC}#{SE}
             )/xno) do
    if    IAC == $1  # handle escaped IAC characters
      IAC
    elsif AYT == $1  # respond to "IAC AYT" (are you there)
      self.write("nobody here but us pigeons" + EOL)
      ''
    elsif DO[0] == $1[0]  # respond to "IAC DO x"
      if OPT_BINARY[0] == $1[1]
        @telnet_option["BINARY"] = true
        self.write(IAC + WILL + OPT_BINARY)
      else
        self.write(IAC + WONT + $1[1..1])
      end
      ''
    elsif DONT[0] == $1[0]  # respond to "IAC DON'T x" with "IAC WON'T x"
      self.write(IAC + WONT + $1[1..1])
      ''
    elsif WILL[0] == $1[0]  # respond to "IAC WILL x"
      if    OPT_BINARY[0] == $1[1]
        self.write(IAC + DO + OPT_BINARY)
      elsif OPT_ECHO[0] == $1[1]
        self.write(IAC + DO + OPT_ECHO)
      elsif OPT_SGA[0]  == $1[1]
        @telnet_option["SGA"] = true
        self.write(IAC + DO + OPT_SGA)
      else
        self.write(IAC + DONT + $1[1..1])
      end
      ''
    elsif WONT[0] == $1[0]  # respond to "IAC WON'T x"
      if    OPT_ECHO[0] == $1[1]
        self.write(IAC + DONT + OPT_ECHO)
      elsif OPT_SGA[0]  == $1[1]
        @telnet_option["SGA"] = false
        self.write(IAC + DONT + OPT_SGA)
      else
        self.write(IAC + DONT + $1[1..1])
      end
      ''
    else
      ''
    end
  end
end

#print(string) ⇒ `Object`

Sends a string to the host.

This does not automatically append a newline to the string. Embedded newlines may be converted and telnet command sequences escaped depending upon the values of telnetmode, binmode, and telnet options set by the host.

# File 'lib/net/telnet.rb', line 625

def print(string)
  string = string.gsub(/#{IAC}/no, IAC + IAC) if @options["Telnetmode"]

  if @options["Binmode"]
    self.write(string)
  else
    if @telnet_option["BINARY"] and @telnet_option["SGA"]
      # IAC WILL SGA IAC DO BIN send EOL --> CR
      self.write(string.gsub(/\n/n, CR))
    elsif @telnet_option["SGA"]
      # IAC WILL SGA send EOL --> CR+NULL
      self.write(string.gsub(/\n/n, CR + NULL))
    else
      # NONE send EOL --> CR+LF
      self.write(string.gsub(/\n/n, EOL))
    end
  end
end

#puts(string) ⇒ `Object`

Sends a string to the host.

Same as #print(), but appends a newline to the string.



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649

# File 'lib/net/telnet.rb', line 647

def puts(string)
  self.print(string + "\n")
end

#telnetmode(mode = nil) ⇒ `Object`

Set telnet command interpretation on (mode == true) or off (mode == false), or return the current value (mode not provided). It should be on for true telnet sessions, off if using Net::Telnet to connect to a non-telnet service such as SMTP.

# File 'lib/net/telnet.rb', line 381

def telnetmode(mode = nil)
  case mode
  when nil
    @options["Telnetmode"]
  when true, false
    @options["Telnetmode"] = mode
  else
    raise ArgumentError, "argument must be true or false, or missing"
  end
end

#telnetmode=(mode) ⇒ `Object`

Turn telnet command interpretation on (true) or off (false). It should be on for true telnet sessions, off if using Net::Telnet to connect to a non-telnet service such as SMTP.

# File 'lib/net/telnet.rb', line 395

def telnetmode=(mode)
  if (true == mode or false == mode)
    @options["Telnetmode"] = mode
  else
    raise ArgumentError, "argument must be true or false"
  end
end

#waitfor(options) ⇒ `Object`

Read data from the host until a certain sequence is matched.

If a block is given, the received data will be yielded as it is read in (not necessarily all in one go), or nil if EOF occurs before any data is received. Whether a block is given or not, all data read will be returned in a single string, or again nil if EOF occurs before any data is received. Note that received data includes the matched sequence we were looking for.

options can be either a regular expression or a hash of options. If a regular expression, this specifies the data to wait for. If a hash, this can specify the following options:

Match: a regular expression, specifying the data to wait for.
Prompt: as for Match; used only if Match is not specified.
String: as for Match, except a string that will be converted into a regular expression. Used only if Match and Prompt are not specified.
Timeout: the number of seconds to wait for data from the host before raising a Timeout::Error. If set to false, no timeout will occur. If not specified, the Timeout option value specified when this instance was created will be used, or, failing that, the default value of 10 seconds.
Waittime: the number of seconds to wait after matching against the input data to see if more data arrives. If more data arrives within this time, we will judge ourselves not to have matched successfully, and will continue trying to match. If not specified, the Waittime option value specified when this instance was created will be used, or, failing that, the default value of 0 seconds, which means not to wait for more input.
FailEOF: if true, when the remote end closes the connection then an EOFError will be raised. Otherwise, defaults to the old behaviour that the function will return whatever data has been received already, or nil if nothing was received.

# File 'lib/net/telnet.rb', line 528

def waitfor(options) # :yield: recvdata
  time_out = @options["Timeout"]
  waittime = @options["Waittime"]
  fail_eof = @options["FailEOF"]

  if options.kind_of?(Hash)
    prompt   = if options.has_key?("Match")
                 options["Match"]
               elsif options.has_key?("Prompt")
                 options["Prompt"]
               elsif options.has_key?("String")
                 Regexp.new( Regexp.quote(options["String"]) )
               end
    time_out = options["Timeout"]  if options.has_key?("Timeout")
    waittime = options["Waittime"] if options.has_key?("Waittime")
    fail_eof = options["FailEOF"]  if options.has_key?("FailEOF")
  else
    prompt = options
  end

  if time_out == false
    time_out = nil
  end

  line = ''
  buf = ''
  rest = ''
  until(prompt === line and not @sock.wait_readable(waittime))
    unless @sock.wait_readable(time_out)
      raise Net::ReadTimeout, "timed out while waiting for more data"
    end
    begin
      c = @sock.readpartial(1024 * 1024)
      @dumplog.log_dump('<', c) if @options.has_key?("Dump_log")
      if @options["Telnetmode"]
        c = rest + c
        if Integer(c.rindex(/#{IAC}#{SE}/no) || 0) <
           Integer(c.rindex(/#{IAC}#{SB}/no) || 0)
          buf = preprocess(c[0 ... c.rindex(/#{IAC}#{SB}/no)])
          rest = c[c.rindex(/#{IAC}#{SB}/no) .. -1]
        elsif pt = c.rindex(/#{IAC}[^#{IAC}#{AO}#{AYT}#{DM}#{IP}#{NOP}]?\z/no) ||
                   c.rindex(/\r\z/no)
          buf = preprocess(c[0 ... pt])
          rest = c[pt .. -1]
        else
          buf = preprocess(c)
          rest = ''
        end
      else
        # Not Telnetmode.
        #
        # We cannot use preprocess() on this data, because that
        # method makes some Telnetmode-specific assumptions.
        buf = rest + c
        rest = ''
        unless @options["Binmode"]
          if pt = buf.rindex(/\r\z/no)
            buf = buf[0 ... pt]
            rest = buf[pt .. -1]
          end
          buf.gsub!(/#{EOL}/no, "\n")
        end
      end
      @log.print(buf) if @options.has_key?("Output_log")
      line += buf
      yield buf if block_given?
    rescue EOFError # End of file reached
      raise if fail_eof
      if line == ''
        line = nil
        yield nil if block_given?
      end
      break
    end
  end
  line
end

#write(string) ⇒ `Object`

Write string to the host.

Does not perform any conversions on string. Will log string to the dumplog, if the Dump_log option is set.

# File 'lib/net/telnet.rb', line 610

def write(string)
  length = string.length
  while 0 < length
    @sock.wait_writable
    @dumplog.log_dump('>', string[-length..-1]) if @options.has_key?("Dump_log")
    length -= @sock.syswrite(string[-length..-1])
  end
end

Class: Net::Telnet

Overview

Net::Telnet

Overview

Examples

Log in and send a command, echoing all output to stdout

Check a POP server to see if you have mail

References

Constant Summary collapse

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ Telnet

Instance Attribute Details

#sock ⇒ Object (readonly)

Instance Method Details

#binmode(mode = nil) ⇒ Object

#binmode=(mode) ⇒ Object

#close ⇒ Object

#cmd(options) ⇒ Object

#login(options, password = nil) ⇒ Object

#preprocess(string) ⇒ Object

#print(string) ⇒ Object

#puts(string) ⇒ Object

#telnetmode(mode = nil) ⇒ Object

#telnetmode=(mode) ⇒ Object

#waitfor(options) ⇒ Object

#write(string) ⇒ Object

#initialize(options) ⇒ `Telnet`

#sock ⇒ `Object` (readonly)

#binmode(mode = nil) ⇒ `Object`

#binmode=(mode) ⇒ `Object`

#close ⇒ `Object`

#cmd(options) ⇒ `Object`

#login(options, password = nil) ⇒ `Object`

#preprocess(string) ⇒ `Object`

#print(string) ⇒ `Object`

#puts(string) ⇒ `Object`

#telnetmode(mode = nil) ⇒ `Object`

#telnetmode=(mode) ⇒ `Object`

#waitfor(options) ⇒ `Object`

#write(string) ⇒ `Object`