The purpose of this lab is to take the concept of using select() from Lab 3 to create an improved version of vcrec and vcsend from Lab 2. This lab is worth 10 points.
In Lab 2, you created a half-duplex form of both vcrec and vcsend by alternating the code to send data and the code to receive data. So the flow of information was:
vcsend vcrec send() -----> recv() recv() <----- send() send() -----> recv() recv() <----- send()For this lab, you are going to alter those send/receive loops in both vcsend and vcrec to instead use
select() to determine whether to call
send() or recv().
You will call send() when there is data on standard in, which
indicates the user has typed something to send, unless the user has typed
just a period (.) on a line by itself, which indicates that the user wishes to
close the connection. Use code similar to vcsend.c to read the data in from
stdin (or your own code with similar functionality). Also be sure to check
the return value of send() as vcsend.c did.
You will call recv() when there is data waiting to be read on
the socket. If recv() is successful (returns greater than 0),
print the data to the screen. Otherwise (returns 0 or negative number),
handle as the original vcrec.c handled those return values of
recv().
Be sure to prompt the user for input before entering the select()
loop and at the end of a normal select() loop iteration (one that
did not error or exit). The prompt can be any text you choose, but be sure to
indicate that the user types '.' on a line by itself to close the connection.
Test your code by running vcrec and then having vcsend connect to vcrec's port. You should be able to type in either program whenever you want and have the data display via stdout on the other program. Both programs should terminate when you type '.' on a single line in either program.
Email me your new and improved versions of vcsend and vcrec.
Also, answer the following questions. In Lab 4, daemon
allowed more than one client to connect at once and would fork off a child
process for each client. One main difference between daemon and this improved
vcrec is that daemon only called recv(), so each child process
only had to receive data from the client and print it to standard out.