Additional hints and cautions for assignment 3:


* make sure you understand that the side that becomes server first sends
  the user name it wants to communicate with (not its own username!)
  
  the client, after receiving this name, sends back the username it wants
  to communicate with.

  If the names do not match on either side, terminate connection.  the
  server should then go back and wait for another connection.

  if names match, the server will initiate the communication by sending
  out the first message, which you get from stdin (the keyboard).


* if your program crashes or breaks out abnormally, you will find it
  impossible to use the same port for connections for a while.  To help
  alleviate this, do the following:
    int x = 1;   // 1 = option on, 0 = off
    setsockopt(sfd,SOL_SOCKET,SO_REUSEADDR,&x,sizeof(int));

  where sfd is the file descriptor for your SERVER socket.  I'll explain
  what this is in more detail later.


* be careful while using fscanf and fprintf over the socket.  Look at the
  man pages for fscanf to understand fully how it works.  Be aware that
  if you try to scan a string, as in scanf("%s",buffer); it will scan
  characters until it sees a while space (space, tab or newline character).
  Now, if you use fscanf to scan a 0-terminated string over a socket, it
  may block.  To solve this situation, make sure when you send the string
  you include an extra white space char in the output, like in:
  
      fprintf(sockstream,"%s ",buffer);


* In general, be aware of the difference between a 0-terminated string
and a string terminated by the newline char '\n'.  When you write a function
to read a line from the keyboard, you want to stop when you see the '\n'
char, but you should also 0-terminate this string!  Otherwise, when you
print the buffer that it scanned into, it will continue printing past the
'\n'.


* Here is a sample session of my solution to the program, on both client and
server.  My program takes the target host ip and the target user as
command-line arguments, as should yours.  ">>" indicates local keyboard
input, and "<<" indicates what's received from the other side.

(from 147.4.150.248 - office solaris machine)  
> ./schat 24.44.52.64 root
Connection Established!
>> how are you?
<<  I'm fine
>> that's nice
<< ok
>> .signoff.

(from 24.44.52.64 - home linux machine)
# ./schat 147.4.150.248 cscccl
Connection Established!
<<  how are you?
>> I'm fine
<< that's nice
>> ok
<< .signoff.

  You should be reading chapters 4 and 5 in the book at this point.  
I will go over forking again next week.

Check webpage frequently for updates.  As of now, however, all due dates
stand.


** I may update this file later with additional comments  **