Class: OverSIP::SIP::TcpConnection

Inherits:
Connection
  • Object
show all
Defined in:
lib/oversip/sip/listeners/tcp_connection.rb

Direct Known Subclasses

TcpClient, TcpServer, TlsTunnelConnection

Constant Summary collapse

HEADERS_MAX_SIZE =

Max size (bytes) of the buffered data when receiving message headers (avoid DoS attacks).

16384

Constants included from MessageProcessor

MessageProcessor::MSG_TYPE

Instance Attribute Summary

Attributes inherited from Connection

#cvars

Instance Method Summary collapse

Methods inherited from Connection

#initialize, #open?, outbound_listener?, #receive_senderror, reliable_transport_listener?, #transport

Methods included from Logger

close, fg_system_msg2str, init_logger_mq, load_methods, #log_id, syslog_system_msg2str, syslog_user_msg2str

Constructor Details

This class inherits a constructor from OverSIP::SIP::Connection

Instance Method Details

#get_body ⇒ Object

parse_headers



174
175
176
177
178
179
180
181
182
183
184
185
186
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 174

def get_body
  # Return false until the buffer gets all the body.
  return false if @buffer.size < @body_length

  ### TODO: Creo que es mejor forzarlo a BINARY y no a UTF-8. Aunque IOBuffer ya lo saca siempre en BINARY.
  # ¿Por qué lo forcé a UTF-8?
  # RESPUESTA: Si no lo hago y resulta que el body no es UTF-8 válido, al añadir el body a los headers (que
  # se generan como un string en UTF-8 (aunque contengan símbolos no UTF-8) fallaría. O todo UTF-8 (aunque
  # tenga símbolos inválidos) o todo BINARY.
  @msg.body = @buffer.read(@body_length).force_encoding(::Encoding::UTF_8)
  @state = :finished
  return true
end

#parse_headers ⇒ Object 



64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 64

def parse_headers
  return false if @buffer.empty?

  # Parse the currently buffered data. If parsing fails @parser_nbytes gets nil value.
  unless @parser_nbytes = @parser.execute(@buffer.to_str, @parser_nbytes)
    # The parsed data is invalid, however some data could be parsed so @parsed.parsed
    # can be:
    # - SIP::Request
    # - SIP::Response
    # - nil (the message is so wrong that cannot be neither a request or response).
    if wrong_message = @parser.parsed
      log_system_warn "parsing error for #{MSG_TYPE[wrong_message.class]}: \"#{@parser.error}\""
    else
      log_system_warn "parsing error: \"#{@parser.error}\""
    end

    close_connection_after_writing
    @state = :ignore
    return false
  end

  # Avoid flood attacks in TCP (very long headers).
  if @parser_nbytes > HEADERS_MAX_SIZE
    log_system_warn "DoS attack detected: headers size exceedes #{HEADERS_MAX_SIZE} bytes, closing connection with #{remote_desc}"
    close_connection
    # After closing client connection some data can still arrrive to "receive_data()"
    # (explained in EM documentation). By setting @state = :ignore we ensure such
    # remaining data is not processed.
    @state = :ignore
    return false
  end

  # If the parsing has not finished, it is correct in TCP so return false and wait for more data under :headers state.
  return false  unless @parser.finished?

  # At this point we've got a SIP::Request, SIP::Response or :outbound_keepalive symbol.
  @msg = @parser.parsed

  # Clear parsed data from the buffer.
  @buffer.read(@parser_nbytes)

  # Received data is a Outbound keealive.
  if @msg == :outbound_keepalive
    log_system_debug "Outbound keepalive received, replying single CRLF"  if $oversip_debug
    # Reply a single CRLF over the same connection.
    send_data CRLF
    # If TCP then go back to :init state so possible remaining data would be processed.
    @state = :init
    return true
  end

  @parser.post_parsing

  # Here we have received the entire headers of a SIP request or response. Fill some
  # attributes.
  @msg.connection = self
  @msg.transport = self.class.transport
  @msg.source_ip = @remote_ip
  @msg.source_port = @remote_port
  @msg.source_ip_type = @remote_ip_type || self.class.ip_type

  unless valid_message? @parser
    close_connection_after_writing
    @state = :ignore
    return false
  end

  add_via_received_rport if @msg.request?

  unless check_via_branch
    close_connection_after_writing
    @state = :ignore
    return false
  end

  # Examine Content-Length header.
  # In SIP over TCP Content-Length header is mandatory.
  if (@body_length = @msg.content_length)
    # There is body (or should be).
    if @body_length > 0
      @state = :body
      # Return true to continue in get_body() method.
      return true
    # No body.
    else
      # Set :finished state and return true to process the parsed message.
      @state = :finished
      return true
    end
  # No Content-Length, invalid message!
  else
    # Log it and reply a 400 Bad Request (if it's a request).
    # Close the connection, set :ignore state and return false to leave
    # receive_data().
    if @msg.request?
      unless @msg.sip_method == :ACK
        log_system_warn "request body size doesn't match Content-Length => 400"
        @msg.reply 400, "Body size doesn't match Content-Length"
      else
        log_system_warn "ACK body size doesn't match Content-Length, ignoring it"
      end
    else
      log_system_warn "response has not Content-Length header, ignoring it"
    end
    close_connection_after_writing
    @state = :ignore
    return false
  end
end

#process_received_data ⇒ Object 



29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 29

def process_received_data
  @state == :ignore and return

  while (case @state
    when :init
      @parser.reset
      @parser_nbytes = 0
      @state = :headers

    when :headers
      parse_headers
      # TODO: Add a timer for the case in which an attacker sends us slow headers that never end:
      #   http://ha.ckers.org/slowloris/.

    when :body
      get_body

    when :finished
      if @msg.request?
        process_request
      else
        process_response
      end

      # Set state to :init.
      @state = :init
      # Return true to continue processing possible remaining data.
      true

    when :ignore
      false
    end)
  end  # while
end

#receive_data(data) ⇒ Object 



21
22
23
24
25
26
27
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 21

def receive_data data
  @state == :ignore and return
  @buffer << data
  @state == :waiting_for_on_client_tls_handshake and return

  process_received_data
end

#remote_ip ⇒ Object 



13
14
15
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 13

def remote_ip
  @remote_ip
end

#remote_ip_type ⇒ Object 



9
10
11
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 9

def remote_ip_type
  @remote_ip_type || self.class.ip_type
end

#remote_port ⇒ Object 



17
18
19
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 17

def remote_port
  @remote_port
end

#send_sip_msg(msg, ip = nil, port = nil) ⇒ Object

Parameters ip and port are just included because they are needed in UDP, so the API remains equal.



190
191
192
193
194
195
196
197
 
# File 'lib/oversip/sip/listeners/tcp_connection.rb', line 190

def send_sip_msg msg, ip=nil, port=nil
  if self.error?
    log_system_notice "SIP message could not be sent, connection is closed"
    return false
  end
  send_data msg
  true
end