Problem sending multiple strings one by one using sockets

Question

I am new to socket programming. Need to send multiple strings one-by-one to server and collect the resulting string.

Now the problem is that using send/write function in client, all the strings are read in one go from server.

//client.c
sendString(serversocket,"str1"); 

sendString(serversocket,"str2"); 

sendString(serversocket,"str3"); 

//server.c

char *buff=readstring(clientsocket);

printf("%s",buff) ;//output : str1str2str2

Need to get str1, str2 and str3...

I need to make it as receive one after another. How can I do this? Any help would be appreciated.

Answer 1

A TCP socket is a byte stream - You will have to split up the data on the receiving end.

For strings, you can do this in e.g. one of these two ways:

Client:

• send an integer length
• send the string data

Server:

• read an integer length
• read this amount of bytes into a string

Or, you can use 0-termination:

Client:

• send a string followed by a 0 byte

Server:

• Read as much as possible, scan for 0 byte, extract string

You will have to handle both of these two cases on the server end:

• Server receives 1 byte for each call to recv()
• Server receives all data in a single call to recv()