src/lib9/udp.c

#include <u.h>
#define NOPLAN9DEFINES
#include <libc.h>
#include <ip.h>

#include <sys/socket.h>
#include <netinet/in.h>

/*
 *  prefix of all v4 addresses
 *  copied from libip because libc cannot depend on libip
 */
static uchar v4prefix[IPaddrlen] = {
	0, 0, 0, 0,
	0, 0, 0, 0,
	0, 0, 0xff, 0xff,
	0, 0, 0, 0
};

long
udpread(int fd, Udphdr *hdr, void *buf, long n)
{
	struct sockaddr_in sin;
	socklen_t len;

	len = sizeof sin;
	n = recvfrom(fd, buf, n, 0, (struct sockaddr*)&sin, &len);
	if(len != sizeof sin){
		werrstr("recvfrom acting weird");
		return -1;
	}
	if(n < 0)
		return -1;
	memset(hdr, 0, sizeof *hdr);
	memmove(hdr->raddr, v4prefix, IPaddrlen);
	*(u32int*)(hdr->raddr+12) = *(u32int*)&sin.sin_addr;
	*(u16int*)hdr->rport = *(u16int*)&sin.sin_port;
	return n;
}

long
udpwrite(int fd, Udphdr *hdr, void *buf, long n)
{
	struct sockaddr_in sin;

	memset(&sin, 0, sizeof sin);
	sin.sin_family = AF_INET;
	*(u32int*)&sin.sin_addr = *(u32int*)(hdr->raddr+12);
	*(u16int*)&sin.sin_port = *(u16int*)hdr->rport;
	return sendto(fd, buf, n, 0, (struct sockaddr*)&sin, sizeof sin);
}