[klibc] [klibc:master] ipconfig: Set broadcast when sending DHCPREQUEST and DHCPDISCOVER

[klibc-bot for Mathieu Trudel-Lapierre]

Commit-ID:  8cb2792d8f7317c336ccc98f99199ae579ac84c6
Gitweb:     http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=8cb2792d8f7317c336ccc98f99199ae579ac84c6
Author:     Mathieu Trudel-Lapierre <mathieu.trudel-lapierre at canonical.com>
AuthorDate: Tue, 24 Jan 2017 10:05:12 -0500
Committer:  Ben Hutchings <ben at decadent.org.uk>
CommitDate: Wed, 2 Jan 2019 03:08:04 +0000

[klibc] ipconfig: Set broadcast when sending DHCPREQUEST and DHCPDISCOVER

We need to do this, since our devices are probably not configured yet and
there may be more than one device we're trying to do DHCP on on the same
network. Otherwise, things might be dropped.

Patch is originally from here:
https://bugs.launchpad.net/ubuntu/+source/klibc/+bug/1327412/comments/5
... but the reporter "patpat" has not provided contact information, and
this is independently verifiable by looking at RFC 2131, section 4.1,
page 24.

References: https://bugs.debian.org/733988
References: https://bugs.launchpad.net/bugs/1327412
Link: https://www.zytor.com/pipermail/klibc/2017-December/003974.html
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>

---
 usr/kinit/ipconfig/dhcp_proto.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/usr/kinit/ipconfig/dhcp_proto.c b/usr/kinit/ipconfig/dhcp_proto.c
index ebf79cc..d5b759b 100644
--- a/usr/kinit/ipconfig/dhcp_proto.c
+++ b/usr/kinit/ipconfig/dhcp_proto.c
@@ -201,8 +201,14 @@ static int dhcp_send(struct netdev *dev, struct iovec *vec)
 	bootp.hlen	= dev->hwlen;
 	bootp.xid	= dev->bootp.xid;
 	bootp.ciaddr	= INADDR_ANY;
-	bootp.yiaddr	= dev->ip_addr;
+	/* yiaddr should always be set to 0 for the messages we're likely
+	 * to send as a DHCP client: DHCPDISCOVER, DHCPREQUEST, DHCPDECLINE,
+	 * DHCPINFORM, DHCPRELEASE
+	 * cf. RFC2131 section 4.1.1, table 5.
+	 */
+	bootp.yiaddr	= INADDR_ANY;
 	bootp.giaddr	= INADDR_ANY;
+	bootp.flags	= htons(0x8000);
 	bootp.secs	= htons(time(NULL) - dev->open_time);
 	memcpy(bootp.chaddr, dev->hwaddr, 16);