From dbfb76673539e5b59dac437c6b2a2159c896731c Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Tue, 25 Sep 2018 15:04:19 +0200
Subject: ip/dhcpd: implement rfc3397 dhcp search domain option (dnsdomain)

---
 sys/src/cmd/ip/dhcp.h        |  2 ++
 sys/src/cmd/ip/dhcpd/dhcpd.c | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/sys/src/cmd/ip/dhcp.h b/sys/src/cmd/ip/dhcp.h
index 59edf4d3b..f69d4502d 100644
--- a/sys/src/cmd/ip/dhcp.h
+++ b/sys/src/cmd/ip/dhcp.h
@@ -111,6 +111,8 @@ enum
 	ODtftpserver=		66,
 	ODbootfile=		67,
 
+	ODdnsdomain=		119,
+
 	/* plan9 vendor info options, v4 addresses only (deprecated) */
 	OP9fsv4=		128,	/* plan9 file servers */
 	OP9authv4=		129,	/* plan9 auth servers */
diff --git a/sys/src/cmd/ip/dhcpd/dhcpd.c b/sys/src/cmd/ip/dhcpd/dhcpd.c
index f0b24edef..d74e6391c 100644
--- a/sys/src/cmd/ip/dhcpd/dhcpd.c
+++ b/sys/src/cmd/ip/dhcpd/dhcpd.c
@@ -161,6 +161,7 @@ char *optname[256] =
 [ODclientid]		"cid",
 [ODtftpserver]		"tftpserver",
 [ODbootfile]		"bf",
+[ODdnsdomain]		"dnsdomain",
 };
 
 void	addropt(Req*, int, uchar*);
@@ -177,6 +178,7 @@ void	maskopt(Req*, int, uchar*);
 void	miscoptions(Req*, uchar*);
 int	openlisten(char *net);
 void	p9addrsopt(Req *rp, int t, uchar **ip, int i);
+void	dnsnamesopt(Req *rp, int t, char *attr, Ndbtuple *nt);
 void	parseoptions(Req*);
 void	proto(Req*, int);
 void	rcvdecline(Req*);
@@ -1170,6 +1172,7 @@ miscoptions(Req *rp, uchar *ip)
 	a = attr;
 	if(*rp->ii.domain == 0)
 		a[na++] = "dom";
+	a[na++] = "dnsdomain";
 	for(i = 0; i < sizeof(rp->requested); i++)
 		switch(rp->requested[i]){
 		case OBrouter:
@@ -1228,6 +1231,9 @@ miscoptions(Req *rp, uchar *ip)
 			if(p != nil)
 				stringopt(rp, OBdomainname, p+1);
 			break;
+		case ODdnsdomain:
+			dnsnamesopt(rp, ODdnsdomain, "dnsdomain", t);
+			break;
 		case OBnetbiosns:
 			j = lookupserver("wins", addrs, nelem(addrs), t);
 			addrsopt(rp, OBnetbiosns, addrs, j);
@@ -1575,6 +1581,40 @@ hexopt(Req *rp, int t, char *str)
 	op = seprint(op, oe, "%s(%s)", optname[t], str);
 }
 
+void
+dnsnamesopt(Req *rp, int t, char *attr, Ndbtuple *nt)
+{
+	char *s;
+	uchar *d;
+	int n, l;
+
+	for(; nt != nil; nt = nt->entry){
+		if(strcmp(nt->attr, attr) != 0)
+			continue;
+		d = &rp->p[2];
+		for(s = nt->val; *s != 0; s++){
+			for(l = 0; *s != 0 && *s != '.'; l++)
+				s++;
+			if(l > 077)
+				goto Skip;
+			d += l+1;
+			if(d >= rp->max)
+				return;
+			d[-l-1] = l;
+			memmove(d-l, s-l, l);
+		}
+		*d++ = 0;
+		n = d - &rp->p[2];
+		if(n > 255)
+			continue;
+		rp->p[0] = t;
+		rp->p[1] = n;
+		rp->p = d;
+		op = seprint(op, oe, "%s(%s)", optname[t], nt->val);
+	Skip:;
+	}
+}
+
 void
 arpenter(uchar *ip, uchar *mac, uchar *src)
 {
-- 
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