[usocket-devel] socket-connect raises non-obvious conditions when given a bad host

[Ryan Davis]

When I try to use socket-connect with a host that can't be resolved, it 
throws an unhelpful error:

Couldn't write to #<SB-SYS:FD-STREAM for "a socket" {C0286C1}>:
  Broken pipe
   [Condition of type SB-INT:SIMPLE-STREAM-ERROR]

Restarts:
 0: [ABORT] Return to SLIME's top level.
 1: [TERMINATE-THREAD] Terminate this thread (#<THREAD "repl-thread" 
{B35FB79}>)

Backtrace:
  0: (SB-IMPL::SIMPLE-STREAM-PERROR "Couldn't write to ~s" 
#<SB-SYS:FD-STREAM for "a socket" {C0286C1}> 32)
  1: (SB-IMPL::SIMPLE-STREAM-PERROR "Couldn't write to ~s" 
#<SB-SYS:FD-STREAM for "a socket" {C0286C1}> 32)
  2: (FORCE-OUTPUT #<SB-SYS:FD-STREAM for "a socket" {C0286C1}>)
  3: (USOCKET-BAD-ERROR)

Here is my test program:

(defun usocket-bad-error ()
  (let  ((s (usocket:socket-stream
         (usocket:socket-connect "doesntexist.example.com" 80))))
    (format s "GET / HTTP/1.1")
    (force-output s);;error thrown here
    s))

Looking through the usocket code, what I would have liked here is a 
bad-host-name condition thrown that I could handle.  I initially thought 
a good spot for this would be in socket-connect, if the ip variable is 
nil, but upon looking at the usocket source so more, I'm not sure if 
there's a better place for that.

Also, I was going to add this as a ticket on the usocket trac, but I 
don't have permission to do that. 

Thanks,

-- 
Ryan Davis
Acceleration.net
Director of Programming Services
2831 NW 41st street, suite B
Gainesville, FL 32606

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