try to do better with headers

1 files changed, 13 insertions, 12 deletions

diff --git a/src/libip/udp.c b/src/libip/udp.c
index 8df03ba0..042aa7e9 100644
--- a/src/libip/udp.c
+++ b/src/libip/udp.c
@@ -6,17 +6,6 @@
 #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)
 {
@@ -24,6 +13,18 @@ udpread(int fd, Udphdr *hdr, void *buf, long n)
 	socklen_t len;
 
 	len = sizeof sin;
+	if(getsockname(fd, (struct sockaddr*)&sin, &len) < 0)
+		return -1;
+	if(len != sizeof sin){
+		werrstr("getsockname acting weird");
+		return -1;
+	}
+	memset(hdr, 0, sizeof *hdr);
+	memmove(hdr->laddr, v4prefix, IPaddrlen);
+	*(u32int*)(hdr->laddr+12) = *(u32int*)&sin.sin_addr;
+	*(u16int*)hdr->lport = *(u16int*)&sin.sin_port;
+
+	len = sizeof sin;
 	n = recvfrom(fd, buf, n, 0, (struct sockaddr*)&sin, &len);
 	if(n < 0)
 		return -1;
@@ -31,10 +32,10 @@ udpread(int fd, Udphdr *hdr, void *buf, long n)
 		werrstr("recvfrom acting weird");
 		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;
 }