From 72dec8120893e76d51e430b4ee5a263e885d0974 Mon Sep 17 00:00:00 2001
From: Dan Williams <dcbw@redhat.com>
Date: Tue, 4 Nov 2014 11:20:43 -0600
Subject: [PATCH] sd-dhcp-client: fix REBOOT state handling

client->secs wasn't getting set in the REBOOT state, causing
an assertion.  REBOOT should work the same way as INIT, per
RFC 2131:

 secs   2  Filled in by client, seconds elapsed since client
           began address acquisition or renewal process.

REBOOT is necessary because some DHCP servers (eg on
home routers) do not hand back the same IP address unless the
'ciaddr' field is filled with that address, which DISCOVER
cannot do per the RFCs.  This leads to multiple leases
on machine reboot or DHCP client restart.

(cherry picked from commit d8d74ef06fa0ccf39084a6177e70e4c2297cca57)
---
 src/libsystemd-network/sd-dhcp-client.c | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 1f7f238ca0..9986b5257b 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -68,7 +68,6 @@ struct sd_dhcp_client {
         uint32_t mtu;
         uint32_t xid;
         usec_t start_time;
-        uint16_t secs;
         unsigned int attempt;
         usec_t request_sent;
         sd_event_source *timeout_t1;
@@ -321,10 +320,12 @@ static int client_message_init(sd_dhcp_client *client, DHCPPacket **ret,
         _cleanup_free_ DHCPPacket *packet;
         size_t optlen, optoffset, size;
         be16_t max_size;
+        usec_t time_now;
+        uint16_t secs;
         int r;
 
         assert(client);
-        assert(client->secs);
+        assert(client->start_time);
         assert(ret);
         assert(_optlen);
         assert(_optoffset);
@@ -344,7 +345,15 @@ static int client_message_init(sd_dhcp_client *client, DHCPPacket **ret,
 
         /* Although 'secs' field is a SHOULD in RFC 2131, certain DHCP servers
            refuse to issue an DHCP lease if 'secs' is set to zero */
-        packet->dhcp.secs = htobe16(client->secs);
+        r = sd_event_now(client->event, clock_boottime_or_monotonic(), &time_now);
+        if (r < 0)
+                return r;
+        assert(time_now >= client->start_time);
+
+        /* seconds between sending first and last DISCOVER
+         * must always be strictly positive to deal with broken servers */
+        secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1;
+        packet->dhcp.secs = htobe16(secs);
 
         /* RFC2132 section 4.1
            A client that cannot receive unicast IP datagrams until its protocol
@@ -441,24 +450,12 @@ static int dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
 static int client_send_discover(sd_dhcp_client *client) {
         _cleanup_free_ DHCPPacket *discover = NULL;
         size_t optoffset, optlen;
-        usec_t time_now;
         int r;
 
         assert(client);
         assert(client->state == DHCP_STATE_INIT ||
                client->state == DHCP_STATE_SELECTING);
 
-        /* See RFC2131 section 4.4.1 */
-
-        r = sd_event_now(client->event, clock_boottime_or_monotonic(), &time_now);
-        if (r < 0)
-                return r;
-        assert(time_now >= client->start_time);
-
-        /* seconds between sending first and last DISCOVER
-         * must always be strictly positive to deal with broken servers */
-        client->secs = ((time_now - client->start_time) / USEC_PER_SEC) ? : 1;
-
         r = client_message_init(client, &discover, DHCP_DISCOVER,
                                 &optlen, &optoffset);
         if (r < 0)
@@ -875,10 +872,8 @@ static int client_start(sd_dhcp_client *client) {
         }
         client->fd = r;
 
-        if (client->state == DHCP_STATE_INIT) {
+        if (client->state == DHCP_STATE_INIT || client->state == DHCP_STATE_INIT_REBOOT)
                 client->start_time = now(clock_boottime_or_monotonic());
-                client->secs = 0;
-        }
 
         return client_initialize_events(client, client_receive_message_raw);
 }