static int udp_csum()

in util/netconsblaster.c [92:112]

• 13 lines of code
• 2 McCabe index (conditional complexity)

static int udp_csum(void *addrptr, void *udppkt, int len)
{
	unsigned int sum = 0;
	uint16_t *addrs = addrptr;
	uint16_t pseudohdr[4] = {0, htons(len), 0, htons(IPPROTO_UDP)};

	sum = ones_complement_sum(addrs, 32, 0);
	sum = ones_complement_sum(pseudohdr, 8, sum);
	sum = ones_complement_sum(udppkt, len, sum);
	sum = ~sum;

	/*
	 * From RFC768: "If the computed checksum is zero, it is transmitted as
	 * all ones. An all zero transmitted checksum value means that the
	 * transmitter generated no checksum"
	 */
	if (sum == 0)
		sum = 65535;

	return sum;
}