[git commit master 1/1] udhcpc: emit maxsize option in all non-NAK type packets
Denys Vlasenko
vda.linux at googlemail.com
Wed Oct 20 19:38:29 UTC 2010
commit: http://git.busybox.net/busybox/commit/?id=b3af65b95de883e9be403e065f57b867d8ea8d43
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master
Before, we were sending them only in DISCOVER packets.
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
networking/udhcp/dhcpc.c | 108 ++++++++++++++++++++++++++++++++++++++--------
1 files changed, 90 insertions(+), 18 deletions(-)
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 9713e81..f685a1d 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -346,31 +346,34 @@ static ALWAYS_INLINE uint32_t random_xid(void)
/* Initialize the packet with the proper defaults */
static void init_packet(struct dhcp_packet *packet, char type)
{
+ /* Fill in: op, htype, hlen, cookie fields; message type option: */
udhcp_init_header(packet, type);
+
+ packet->xid = random_xid();
+
memcpy(packet->chaddr, client_config.client_mac, 6);
if (client_config.clientid)
udhcp_add_binary_option(packet, client_config.clientid);
+}
+
+static void add_client_options(struct dhcp_packet *packet)
+{
+ uint8_t c;
+ int i, end, len;
+
+ udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
if (client_config.hostname)
udhcp_add_binary_option(packet, client_config.hostname);
if (client_config.fqdn)
udhcp_add_binary_option(packet, client_config.fqdn);
- if (type != DHCPDECLINE
- && type != DHCPRELEASE
- && client_config.vendorclass
- ) {
+ if (client_config.vendorclass)
udhcp_add_binary_option(packet, client_config.vendorclass);
- }
-}
-static void add_client_options(struct dhcp_packet *packet)
-{
/* Add a "param req" option with the list of options we'd like to have
* from stubborn DHCP servers. Pull the data from the struct in common.c.
* No bounds checking because it goes towards the head of the packet. */
- uint8_t c;
- int end = udhcp_end_option(packet->options);
- int i, len = 0;
-
+ end = udhcp_end_option(packet->options);
+ len = 0;
for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
if (( (dhcp_optflags[i].flags & OPTION_REQ)
&& !client_config.no_default_options
@@ -432,13 +435,20 @@ static int send_discover(uint32_t xid, uint32_t requested)
{
struct dhcp_packet packet;
+ /* Fill in: op, htype, hlen, cookie, chaddr fields,
+ * random xid field (we override it below),
+ * client-id option (unless -C), message type option:
+ */
init_packet(&packet, DHCPDISCOVER);
+
packet.xid = xid;
if (requested)
udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
- /* Explicitly saying that we want RFC-compliant packets helps
- * some buggy DHCP servers to NOT send bigger packets */
- udhcp_add_simple_option(&packet, DHCP_MAX_SIZE, htons(576));
+
+ /* Add options: maxsize,
+ * optionally: hostname, fqdn, vendorclass,
+ * "param req" option according to -O, options specified with -x
+ */
add_client_options(&packet);
bb_info_msg("Sending discover...");
@@ -454,10 +464,33 @@ static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
struct dhcp_packet packet;
struct in_addr addr;
+/*
+ * RFC 2131 4.3.2 DHCPREQUEST message
+ * ...
+ * If the DHCPREQUEST message contains a 'server identifier'
+ * option, the message is in response to a DHCPOFFER message.
+ * Otherwise, the message is a request to verify or extend an
+ * existing lease. If the client uses a 'client identifier'
+ * in a DHCPREQUEST message, it MUST use that same 'client identifier'
+ * in all subsequent messages. If the client included a list
+ * of requested parameters in a DHCPDISCOVER message, it MUST
+ * include that list in all subsequent messages.
+ */
+ /* Fill in: op, htype, hlen, cookie, chaddr fields,
+ * random xid field (we override it below),
+ * client-id option (unless -C), message type option:
+ */
init_packet(&packet, DHCPREQUEST);
+
packet.xid = xid;
udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
+
udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
+
+ /* Add options: maxsize,
+ * optionally: hostname, fqdn, vendorclass,
+ * "param req" option according to -O, and options specified with -x
+ */
add_client_options(&packet);
addr.s_addr = requested;
@@ -470,9 +503,33 @@ static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
{
struct dhcp_packet packet;
+/*
+ * RFC 2131 4.3.2 DHCPREQUEST message
+ * ...
+ * DHCPREQUEST generated during RENEWING state:
+ *
+ * 'server identifier' MUST NOT be filled in, 'requested IP address'
+ * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
+ * client's IP address. In this situation, the client is completely
+ * configured, and is trying to extend its lease. This message will
+ * be unicast, so no relay agents will be involved in its
+ * transmission. Because 'giaddr' is therefore not filled in, the
+ * DHCP server will trust the value in 'ciaddr', and use it when
+ * replying to the client.
+ */
+ /* Fill in: op, htype, hlen, cookie, chaddr fields,
+ * random xid field (we override it below),
+ * client-id option (unless -C), message type option:
+ */
init_packet(&packet, DHCPREQUEST);
+
packet.xid = xid;
packet.ciaddr = ciaddr;
+
+ /* Add options: maxsize,
+ * optionally: hostname, fqdn, vendorclass,
+ * "param req" option according to -O, and options specified with -x
+ */
add_client_options(&packet);
bb_info_msg("Sending renew...");
@@ -489,9 +546,20 @@ static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
{
struct dhcp_packet packet;
+ /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
+ * client-id option (unless -C), message type option:
+ */
init_packet(&packet, DHCPDECLINE);
+
+ /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
+ * but in case the server is buggy and wants DHCPDECLINE's xid
+ * to match the xid which started entire handshake,
+ * we use the same xid we used in initial DHCPDISCOVER:
+ */
packet.xid = xid;
+ /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
+
udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
bb_info_msg("Sending decline...");
@@ -504,8 +572,12 @@ static int send_release(uint32_t server, uint32_t ciaddr)
{
struct dhcp_packet packet;
+ /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
+ * client-id option (unless -C), message type option:
+ */
init_packet(&packet, DHCPRELEASE);
- packet.xid = random_xid();
+
+ /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
packet.ciaddr = ciaddr;
udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
@@ -1254,7 +1326,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
/* Ignore packets that aren't for us */
if (packet.hlen != 6
- || memcmp(packet.chaddr, client_config.client_mac, 6)
+ || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
) {
//FIXME: need to also check that last 10 bytes are zero
log1("chaddr does not match, ignoring packet"); // log2?
@@ -1280,7 +1352,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
}
/* it IS unaligned sometimes, don't "optimize" */
move_from_unaligned32(server_addr, temp);
- xid = packet.xid;
+ /*xid = packet.xid; - already is */
requested_ip = packet.yiaddr;
/* enter requesting state */
--
1.7.1
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