minimal plan9port to cross-build Jehanne

lib/lib9/udp.c

@@ -0,0 +1,51 @@
+#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);
+}