Coverage for /pythoncovmergedfiles/medio/medio/src/paramiko/paramiko/proxy.py: 36%

1# Copyright (C) 2012 Yipit, Inc <coders@yipit.com> 

2# 

3# This file is part of paramiko. 

4# 

5# Paramiko is free software; you can redistribute it and/or modify it under the 

6# terms of the GNU Lesser General Public License as published by the Free 

7# Software Foundation; either version 2.1 of the License, or (at your option) 

8# any later version. 

9# 

10# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY 

11# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR 

12# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more 

13# details. 

14# 

15# You should have received a copy of the GNU Lesser General Public License 

16# along with Paramiko; if not, write to the Free Software Foundation, Inc., 

17# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 

18 

19 

20import os 

21import shlex 

22import signal 

23from select import select 

24import socket 

25import time 

26 

27# Try-and-ignore import so platforms w/o subprocess (eg Google App Engine) can 

28# still import paramiko. 

29subprocess, subprocess_import_error = None, None 

30try: 

31 import subprocess 

32except ImportError as e: 

33 subprocess_import_error = e 

34 

35from paramiko.ssh_exception import ProxyCommandFailure 

36from paramiko.util import ClosingContextManager 

37 

38 

39class ProxyCommand(ClosingContextManager): 

40 """ 

41 Wraps a subprocess running ProxyCommand-driven programs. 

42 

43 This class implements a the socket-like interface needed by the 

44 `.Transport` and `.Packetizer` classes. Using this class instead of a 

45 regular socket makes it possible to talk with a Popen'd command that will 

46 proxy traffic between the client and a server hosted in another machine. 

47 

48 Instances of this class may be used as context managers. 

49 """ 

50 

51 def __init__(self, command_line): 

52 """ 

53 Create a new CommandProxy instance. The instance created by this 

54 class can be passed as an argument to the `.Transport` class. 

55 

56 :param str command_line: 

57 the command that should be executed and used as the proxy. 

58 """ 

59 if subprocess is None: 

60 raise subprocess_import_error 

61 self.cmd = shlex.split(command_line) 

62 self.process = subprocess.Popen( 

63 self.cmd, 

64 stdin=subprocess.PIPE, 

65 stdout=subprocess.PIPE, 

66 stderr=subprocess.PIPE, 

67 bufsize=0, 

68 ) 

69 self.timeout = None 

70 

71 def send(self, content): 

72 """ 

73 Write the content received from the SSH client to the standard 

74 input of the forked command. 

75 

76 :param str content: string to be sent to the forked command 

77 """ 

78 try: 

79 self.process.stdin.write(content) 

80 except IOError as e: 

81 # There was a problem with the child process. It probably 

82 # died and we can't proceed. The best option here is to 

83 # raise an exception informing the user that the informed 

84 # ProxyCommand is not working. 

85 raise ProxyCommandFailure(" ".join(self.cmd), e.strerror) 

86 return len(content) 

87 

88 def recv(self, size): 

89 """ 

90 Read from the standard output of the forked program. 

91 

92 :param int size: how many chars should be read 

93 

94 :return: the string of bytes read, which may be shorter than requested 

95 """ 

96 try: 

97 buffer = b"" 

98 start = time.time() 

99 while len(buffer) < size: 

100 select_timeout = None 

101 if self.timeout is not None: 

102 elapsed = time.time() - start 

103 if elapsed >= self.timeout: 

104 raise socket.timeout() 

105 select_timeout = self.timeout - elapsed 

106 

107 r, w, x = select([self.process.stdout], [], [], select_timeout) 

108 if r and r[0] == self.process.stdout: 

109 buffer += os.read( 

110 self.process.stdout.fileno(), size - len(buffer) 

111 ) 

112 return buffer 

113 except socket.timeout: 

114 if buffer: 

115 # Don't raise socket.timeout, return partial result instead 

116 return buffer 

117 raise # socket.timeout is a subclass of IOError 

118 except IOError as e: 

119 raise ProxyCommandFailure(" ".join(self.cmd), e.strerror) 

120 

121 def close(self): 

122 os.kill(self.process.pid, signal.SIGTERM) 

123 

124 @property 

125 def closed(self): 

126 return self.process.returncode is not None 

127 

128 @property 

129 def _closed(self): 

130 # Concession to Python 3 socket-like API 

131 return self.closed 

132 

133 def settimeout(self, timeout): 

134 self.timeout = timeout