commit d3d795868cb6ad9a86b9499d50e7a604cc399f6b
Author: lufia <lufia@lufia.org>
Date:   Tue Sep 22 20:57:30 2020 +0900

    sys/src/9/ip: direct attached network

diff --git a/sys/src/9/ip/ip.c b/sys/src/9/ip/ip.c
index 098e46f56..3b0cab82e 100644
--- a/sys/src/9/ip/ip.c
+++ b/sys/src/9/ip/ip.c
@@ -129,6 +129,7 @@ ipoput4(Fs *f, Block *bp, int gating, int ttl, int tos, Conv *c)
 	Route *r, *sr;
 	IP *ip;
 	int rv = 0;
+	uchar v4dst[IPv4addrlen];
 
 	ip = f->ip;
 
@@ -169,7 +170,11 @@ ipoput4(Fs *f, Block *bp, int gating, int ttl, int tos, Conv *c)
 		gate = eh->dst;
 	else
 	if(r->type & (Rbcast|Rmulti)) {
-		gate = eh->dst;
+		if(nhgetl(r->v4.gate) == 0){
+			hnputl(v4dst, r->v4.address);
+			gate = v4dst;
+		}else
+			gate = eh->dst;
 		sr = v4lookup(f, eh->src, nil);
 		if(sr != nil && (sr->type & Runi))
 			ifc = sr->ifc;
diff --git a/sys/src/9/ip/iproute.c b/sys/src/9/ip/iproute.c
index e7646c72e..70c816429 100644
--- a/sys/src/9/ip/iproute.c
+++ b/sys/src/9/ip/iproute.c
@@ -493,6 +493,7 @@ v4lookup(Fs *f, uchar *a, Conv *c)
 		return c->r;
 
 	la = nhgetl(a);
+again:
 	q = nil;
 	for(p=f->v4root[V4H(la)]; p;)
 		if(la >= p->v4.address) {
@@ -511,8 +512,14 @@ v4lookup(Fs *f, uchar *a, Conv *c)
 		} else
 			v4tov6(gate, q->v4.gate);
 		ifc = findipifc(f, gate, q->type);
-		if(ifc == nil)
+		if(ifc == nil){
+			/* find a direct attached route */
+			if(q->v4.address == 0 && q->v4.endaddress == ~0){
+				la = nhgetl(q->v4.gate);
+				goto again;
+			}
 			return nil;
+		}
 		q->ifc = ifc;
 		q->ifcid = ifc->ifcid;
 	}
@@ -817,6 +824,7 @@ routewrite(Fs *f, Chan *c, char *p, int n)
 	uchar gate[IPaddrlen];
 	IPaux *a, *na;
 	Route *q;
+	uchar type;
 
 	cb = parsecmd(p, n);
 	if(waserror()){
@@ -863,9 +871,12 @@ routewrite(Fs *f, Chan *c, char *p, int n)
 			a = c->aux;
 			tag = a->tag;
 		}
-		if(memcmp(addr, v4prefix, IPv4off) == 0)
-			v4addroute(f, tag, addr+IPv4off, mask+IPv4off, gate+IPv4off, 0);
-		else
+		if(memcmp(addr, v4prefix, IPv4off) == 0){
+			type = 0;
+			if(ipcmp(mask, IPallbits) == 0)
+				type = Rbcast;
+			v4addroute(f, tag, addr+IPv4off, mask+IPv4off, gate+IPv4off, type);
+		}else
 			v6addroute(f, tag, addr, mask, gate, 0);
 	} else if(strcmp(cb->f[0], "tag") == 0) {
 		if(cb->nf < 2)