Handling the CC Variable

Two global variables are added to the TCP/IP suite, tcp_ccgen, which is used as the counter for the CC value, and tcp_do_rfc1644 which indicates whether to send CC options in the outgoing segments. These are declared as follows:

unsigned long tcp_ccgen = 0;

int tcp_do_rfc1644 = 1;

The macro CC_INC is defined to allow the tcp_ccgen variable to be incremented. If this variable is zero, it means undefined, the macro adds one if the variable is zero. This is defined as:

#define CC_INC(c) (++(c) == 0 ? ++(c) : (c))