| 15.3
|
Start with Figure 11.11 and
modify it to call sleep(5) after the peer's protocol
address is printed, and to also print the number of bytes returned
by read each time read returns a positive
value.
Start with Figure 11.14 and
modify it to call write for each byte of the result that
is sent to the client. (We discussed similar modifications in the
solution to Exercise 1.5.)
Run the client and server on the same host using TCP. How many
bytes are read by the client?
Run the client and server on the same host using
a Unix domain socket. Does anything change?
Now call send instead of write
in the server and specify the MSG_EOR flag. (You need a
Berkeley-derived implementation to finish this exercise.) Run the
client and server on the same host using a Unix domain socket. Does
anything change?
|
| 15.4
|
Write a program to determine the values shown in
Figure 4.10. One
approach is to create a stream pipe and then fork into a
parent and child. The parent enters a for loop,
incrementing the backlog from 0 through 14. Each time through the
loop, the parent first writes the value of the backlog to the
stream pipe. The child reads this value, creates a listening socket
bound to the loopback address, and sets the backlog to that value.
The child then writes to the stream pipe, just to tell the parent
it is ready. The parent then attempts as many connections as
possible, detecting when it has hit the backlog limit because the
connect blocks. The parent may use an alarm set
at two seconds to detect the blocking connect. The child
never calls accept to let the kernel queue the connections
from the parent. When the parent's alarm expires, it knows
from the loop counter which connect hit the backlog limit.
The parent then closes its sockets and writes the next new backlog
value to the stream pipe for the child. When the child reads this
next value, it closes its listening socket and creates a new
listening socket, starting the procedure again.
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