Bug 912382

Summary: SOCK_STREAM TCP: send() returns success even other side responded with RST packet
Product: [Fedora] Fedora Reporter: Tomáš Hozza <thozza>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 18CC: gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda, poros, schaiba
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Hardware: Unspecified   
OS: Unspecified   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2013-02-19 15:49:24 UTC Type: Bug
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Flags
Client source
none
Server source none

Description Tomáš Hozza 2013-02-18 15:01:51 UTC 
Description of problem:
I'm using SOCK_STREAM TCP sockets. Imagine server-client application.
- Server will accept connection from client.
- Client sends some data to server -> server receives data.
- Client then half-closes the TCP connection using shutdown(fd, SHUT_WR).
- Client waits for some data from the server.
- Server sends some data to client -> client receives data.
- Client exits and closes the socket.
- After some time server tries to send some data to the client.
- The first send() call returns success even the Client's response is RST.


Version-Release number of selected component (if applicable):
3.7.7-201.fc18.x86_64

How reproducible:
always

Steps to Reproduce:
1. download attached client/server sources.
2. compile server: # gcc tcp_server.c -o server
3. compile client: # gcc tcp_client.c -o client
4. run the server: # ./server
5. run the client: # ./client
  
Actual results:
Server started...
Created SOCK_STREAM socket
Bound to localhost:6666
waiting for connection...
Client connected!
Waiting for some data from client
Received: "MSG from client"
Received EOF
Sending msg to client: "MSG from server"
sleep(5)
Sending 1 msg to client: "MSG from server"
try #1 send() result: (0) Success
Sending 2 msg to client: "MSG from server"
try #2 send() result: (32) Broken pipe
Server exiting...


Expected results:
Server should fail to send() data right after sleep().

Server started...
Created SOCK_STREAM socket
Bound to localhost:6666
waiting for connection...
Client connected!
Waiting for some data from client
Received: "MSG from client"
Received EOF
Sending msg to client: "MSG from server"
sleep(5)
Sending 1 msg to client: "MSG from server"
try #1 send() result: (32) Broken pipe
Server exiting...


Additional info:
RST answer means that data were NOT delivered. Therefore the very
first send() call after server sleep() should fail!
Comment 1 Tomáš Hozza 2013-02-18 15:03:07 UTC 
Created attachment 698913 [details]
Client source
Comment 2 Tomáš Hozza 2013-02-18 15:03:31 UTC 
Created attachment 698914 [details]
Server source
Comment 3 Tomáš Hozza 2013-02-18 18:19:57 UTC 
Still an issue on 3.7.8-202.fc18.x86_64.
Comment 4 Dave Jones 2013-02-18 19:31:57 UTC 
can you report this to netdev.org ?  Dealing with the networking developers directly is likely to get your problem fixed a lot faster than us acting as man-in-the-middle here.
Comment 5 Tomáš Hozza 2013-02-19 07:02:33 UTC 
(In reply to comment #4)
> can you report this to netdev.org ?  Dealing with the networking
> developers directly is likely to get your problem fixed a lot faster than us
> acting as man-in-the-middle here.

I did. Thank you.
Comment 6 Tomáš Hozza 2013-02-19 15:49:24 UTC 
Since send() is not blocking AND send() returning success does not mean
that data were delivered is not a Bug. Closing as NOTABUG.