Testing socket connection in Python

Question

This question will expand on  Best way to open a socket in Python When opening a socket how can I test to see if it has been established  and that it did not timeout  or generally fail   Edit  I tried this   try      s connect  address   80    except      alert  failed    address   down     but the alert function is called even when that connection should have worked

User · Answer

12 years later for anyone having similar problems.

try:
    s.connect((address, '80'))
except:
    alert('failed' + address, 'down')

doesn't work because the port '80' is a string. Your port needs to be int.

try:
    s.connect((address, 80))

This should work. Not sure why even the best answer didnt see this.

User · Answer

You should really post    The complete source code of your example The actual result of it  not a summary   Here is my code  which works   import socket  sys  def alert msg       print  gt  gt sys stderr  msg     sys exit 1    family  socktype  proto  garbage  address               socket getaddrinfo    1    http   0    Use only the first tuple s   socket socket family  socktype  proto   try      s connect address   except Exception  e      alert  Something s wrong with  s  Exception type is  s     address  e     When the server listens  I get nothing  this is normal   when it doesn t  I get the expected message   Something s wrong with     1   80  0  0   Exception type is  111   Connection refused

User · Answer

You should really post    The complete source code of your example The actual result of it  not a summary   Here is my code  which works   import socket  sys  def alert msg       print  gt  gt sys stderr  msg     sys exit 1    family  socktype  proto  garbage  address               socket getaddrinfo    1    http   0    Use only the first tuple s   socket socket family  socktype  proto   try      s connect address   except Exception  e      alert  Something s wrong with  s  Exception type is  s     address  e     When the server listens  I get nothing  this is normal   when it doesn t  I get the expected message   Something s wrong with     1   80  0  0   Exception type is  111   Connection refused

User · Answer

It seems that you catch not the exception you wanna catch out there     if the s is a socket socket   object  then the right way to call  connect would be   import socket s   socket socket   address    127 0 0 1  port   80    port number is a number  not string try      s connect  address  port          originally  it was        except Exception  e         but this syntax is not supported anymore   except Exception as e       print  something s wrong with  s  d  Exception is  s     address  port  e   finally      s close     Always try to see what kind of exception is what you re catching in a try-except loop     You can check what types of exceptions in a socket module represent what kind of errors  timeout  unable to resolve address  etc  and make separate except statement for each one of them - this way you ll be able to react differently for different kind of problems

User · Answer

It seems that you catch not the exception you wanna catch out there     if the s is a socket socket   object  then the right way to call  connect would be   import socket s   socket socket   address    127 0 0 1  port   80    port number is a number  not string try      s connect  address  port          originally  it was        except Exception  e         but this syntax is not supported anymore   except Exception as e       print  something s wrong with  s  d  Exception is  s     address  port  e   finally      s close     Always try to see what kind of exception is what you re catching in a try-except loop     You can check what types of exceptions in a socket module represent what kind of errors  timeout  unable to resolve address  etc  and make separate except statement for each one of them - this way you ll be able to react differently for different kind of problems

User · Answer

You can use the function connect ex  It doesn t throw an exception  Instead of that  returns a C style integer value  referred to as errno in C    s    socket socket socket AF INET  socket SOCK STREAM  result   s connect ex  host  port   s close   if result      print  problem with socket   else      print  everything it s ok

User · Answer

It seems that you catch not the exception you wanna catch out there     if the s is a socket socket   object  then the right way to call  connect would be   import socket s   socket socket   address    127 0 0 1  port   80    port number is a number  not string try      s connect  address  port          originally  it was        except Exception  e         but this syntax is not supported anymore   except Exception as e       print  something s wrong with  s  d  Exception is  s     address  port  e   finally      s close     Always try to see what kind of exception is what you re catching in a try-except loop     You can check what types of exceptions in a socket module represent what kind of errors  timeout  unable to resolve address  etc  and make separate except statement for each one of them - this way you ll be able to react differently for different kind of problems

User · Answer

12 years later for anyone having similar problems.

try:
    s.connect((address, '80'))
except:
    alert('failed' + address, 'down')

doesn't work because the port '80' is a string. Your port needs to be int.

try:
    s.connect((address, 80))

This should work. Not sure why even the best answer didnt see this.

User · Answer

It seems that you catch not the exception you wanna catch out there     if the s is a socket socket   object  then the right way to call  connect would be   import socket s   socket socket   address    127 0 0 1  port   80    port number is a number  not string try      s connect  address  port          originally  it was        except Exception  e         but this syntax is not supported anymore   except Exception as e       print  something s wrong with  s  d  Exception is  s     address  port  e   finally      s close     Always try to see what kind of exception is what you re catching in a try-except loop     You can check what types of exceptions in a socket module represent what kind of errors  timeout  unable to resolve address  etc  and make separate except statement for each one of them - this way you ll be able to react differently for different kind of problems

User · Answer

You can use the function connect ex  It doesn t throw an exception  Instead of that  returns a C style integer value  referred to as errno in C    s    socket socket socket AF INET  socket SOCK STREAM  result   s connect ex  host  port   s close   if result      print  problem with socket   else      print  everything it s ok

User · Answer

You should really post    The complete source code of your example The actual result of it  not a summary   Here is my code  which works   import socket  sys  def alert msg       print  gt  gt sys stderr  msg     sys exit 1    family  socktype  proto  garbage  address               socket getaddrinfo    1    http   0    Use only the first tuple s   socket socket family  socktype  proto   try      s connect address   except Exception  e      alert  Something s wrong with  s  Exception type is  s     address  e     When the server listens  I get nothing  this is normal   when it doesn t  I get the expected message   Something s wrong with     1   80  0  0   Exception type is  111   Connection refused

User · Answer

You should really post    The complete source code of your example The actual result of it  not a summary   Here is my code  which works   import socket  sys  def alert msg       print  gt  gt sys stderr  msg     sys exit 1    family  socktype  proto  garbage  address               socket getaddrinfo    1    http   0    Use only the first tuple s   socket socket family  socktype  proto   try      s connect address   except Exception  e      alert  Something s wrong with  s  Exception type is  s     address  e     When the server listens  I get nothing  this is normal   when it doesn t  I get the expected message   Something s wrong with     1   80  0  0   Exception type is  111   Connection refused

[python] Testing socket connection in Python

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