Bug 12274 - System.Net.Dns.BeginGetHostAddresses throws unhandled SocketException if networking is disabled
Summary: System.Net.Dns.BeginGetHostAddresses throws unhandled SocketException if netw...
Alias: None
Product: Class Libraries
Classification: Mono
Component: System ()
Version: 2.10.x
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Martin Baulig
Depends on:
Reported: 2013-05-16 23:04 UTC by Matt Greer
Modified: 2016-11-11 09:43 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

Small repro of the issue (469 bytes, text/plain)
2013-05-16 23:05 UTC, Matt Greer

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Description Matt Greer 2013-05-16 23:04:39 UTC
With networking disabled, System.Net.Dns.BeginGetHostAddress() throws a SocketException with the error "no host found". This exception is unhandled and thrown in a background thread, causing the application to crash with no hope of catching the exception since it's in a thread beyond the developer's control.

1) Take the attached example and compile it in MonoDevelop on Linux
2) Run the application with access to the internet (networking is enabled)

expect: no issues, application completes normally
actual: as expected

3) turn off networking (for me, on Ubuntu 12, I unselected "Enable Wireless" from the wifi menu.
4) Run the app again

expected: no issues, application fails to look up the DNS entry for the provided name but does not crash
actual: crashes with an unhandled SocketException.

my environment:
OS: Ubuntu 12.04.2 LTS "Precise", 32 bit
Mono: Mono JIT compiler version (Debian 
Hardware: 7 year old MacBook with an Intel processor
Comment 1 Matt Greer 2013-05-16 23:05:19 UTC
Created attachment 3979 [details]
Small repro of the issue
Comment 2 Matt Greer 2013-05-16 23:06:26 UTC
This is Linux specific. At the very least, this does not happen on OSX Mountain Lion with Mono 2.10.12
Comment 3 Martin Baulig 2016-11-11 09:43:18 UTC
Closing ancient bugs, please reopen if you're still having this problem.