服务器连接不同的套接字端口

Question

I have read a question on a mock interview. Here is the question...

Code a C++ program to connect a server (ex. IP:192.168.10.131) on 2 different sockets on port 2345,4325, simultaneously..

My doubt is wheather it is saying create 2 sockets with common interface ip 192.168.10.131 and port 2345,4325 respectively. Or it is saying connect a server having interface ip 192.168.10.131 to two different connection sockets on another server machine on different sockets port..

If i am guessing first one right then I just need to create two socket connection and start these on individual thread.

If 2 nd one is right how i need to do that.... Please help...

Answer 1

The simplest interpretation (which is probably correct in the context of an interview, but of course you'd ask) is to create two sockets and connect one to each of the given ports on the given IP address.

A TCP connection is defined by the 4-tuple (source address, source port, destination address, destination port). The source address and port are usually irrelevant to such questions because they'll be chosen automatically by default. So when the question says "on 2 different sockets on port 2345,4325" the most likely interpretation is that those are the destination ports from the client's perspective.

So it's really two calls to socket(2) and two calls to connect(2) with perhaps a sprinkling of other functions like inet_pton(3) .

As for "simultaneously," yes you could use threads, but a likely better solution is to multiplex them using select(2) . Being too quick to jump to a multithreaded solution can be a red flag in an interview. Again, you'd want to ask about this.