On Tuesday 01 April 2008 23:09, L. Gabriel Somlo wrote:
> Denys & All,
>
> I noticed that udhcpc sends a default list of options in its request
> (i.e., all options listed with flag OPTION_REQ in options.c)
>
> That's bad, at least when used with some versions of isc dhcpd, which
> will only include the requested options in a reply.
>
> I know about the -O flag that can get udhcpc to request extra options,
> but what if I want to see options I didn't think about asking for ?
> Including a default option list in the request will always preclude me
> from seeing options I didn't know to ask for.
USE_FEATURE_UDHCPC_ARPING( \
"\n -a,--arping Use arping to validate offered address" \
) \
+ "\n -o,--no-default-options Do not request options by default" \
) \
SKIP_GETOPT_LONG( \
SKIP_GETOPT_LONG case also needs -o covered.
- "O:"
+ "O:o:"
-o does not take a param, should be "O:o".
packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
- if ((dhcp_options[i].flags & OPTION_REQ)
+ if (((dhcp_options[i].flags & OPTION_REQ) &&
!client_config.no_default_options) //vda
|| (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
) {
packet->options[end + OPT_DATA + len] = c;
len++;
}
so, you create "empty" DHCP_PARAM_REQ. Why not just omitting it
at all like this?
- add_param_req_option(&packet);
+ if (!client_config.no_default_options)
+ add_param_req_option(&packet);
> I've added the '-o' command line flag to udhcpc, which inhibits
> inclusion of default options in the request. Options can still be
> explicitly requested with -O.
I am thinking - maybe we should just junk the idea of "default"
options to ask for? We can ask user to always provide explicit
list of -O OPTs to ask. What do you think?
> I have also added a mechanism to request '-o' (actually, its long form
> --no-default-options) from ifupdown's /etc/network/interfaces:
>
> auto eth0
> iface eth0 inet dhcp
> nodefaultopts --no-default-options
Please take a look at attached patch - will this work for you?
--
vda
diff -d -urpN busybox.3/include/usage.h busybox.4/include/usage.h
--- busybox.3/include/usage.h 2008-03-31 21:26:17.000000000 +0200
+++ busybox.4/include/usage.h 2008-04-02 01:36:14.000000000 +0200
@@ -4116,7 +4116,7 @@
"Adjust filesystem options on ext[23] filesystems"
#define udhcpc_trivial_usage \
- "[-Cfbnqtv] [-c CID] [-V VCLS] [-H HOSTNAME] [-i INTERFACE]\n" \
+ "[-Cfbnqtvo] [-c CID] [-V VCLS] [-H HOSTNAME] [-i INTERFACE]\n" \
" [-p pidfile] [-r IP] [-s script] [-O dhcp-option]..." USE_FEATURE_UDHCP_PORT(" [-P N]")
#define udhcpc_full_usage \
USE_GETOPT_LONG( \
@@ -4131,13 +4131,14 @@
"\n -t,--retries=N Send up to N request packets" \
"\n -T,--timeout=N Try to get a lease for N seconds (default 3)" \
"\n -A,--tryagain=N Wait N seconds (default 20) after failure" \
+ "\n -O,--request-option=OPT Request DHCP option OPT from server" \
+ "\n -o,--no-default-options Do not request options by default" \
"\n -f,--foreground Run in foreground" \
"\n -b,--background Background if lease is not immediately obtained" \
"\n -S,--syslog Log to syslog too" \
"\n -n,--now Exit with failure if lease is not immediately obtained" \
"\n -q,--quit Quit after obtaining lease" \
"\n -R,--release Release IP on quit" \
- "\n -O,--request-option=OPT Request DHCP option OPT from server" \
USE_FEATURE_UDHCP_PORT( \
"\n -P,--client-port N Use port N instead of default 68" \
) \
@@ -4157,13 +4158,14 @@
"\n -t N Send up to N request packets" \
"\n -T N Try to get a lease for N seconds (default 3)" \
"\n -A N Wait N seconds (default 20) after failure" \
+ "\n -O OPT Request DHCP option OPT from server" \
+ "\n -o Do not request options by default" \
"\n -f Run in foreground" \
"\n -b Background if lease is not immediately obtained" \
"\n -S Log to syslog too" \
"\n -n Exit with failure if lease is not immediately obtained" \
"\n -q Quit after obtaining lease" \
"\n -R Release IP on quit" \
- "\n -O OPT Request DHCP option OPT from server" \
USE_FEATURE_UDHCP_PORT( \
"\n -P N Use port N instead of default 68" \
) \
diff -d -urpN busybox.3/networking/ifupdown.c busybox.4/networking/ifupdown.c
--- busybox.3/networking/ifupdown.c 2008-03-31 21:26:06.000000000 +0200
+++ busybox.4/networking/ifupdown.c 2008-04-02 01:47:14.000000000 +0200
@@ -476,7 +476,8 @@ static const struct dhcp_client_t ext_dh
"pump -i %iface% -k",
},
{ "udhcpc",
- "udhcpc -R -n -p /var/run/udhcpc.%iface%.pid -i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]][[ -t %retries%]]",
+ "udhcpc -R -n -p /var/run/udhcpc.%iface%.pid -i %iface%[[ -H %hostname%]][[ -c %clientid%]]"
+ "[[ -s %script%]][[ %udhcpc_opts%]]",
"kill `cat /var/run/udhcpc.%iface%.pid` 2>/dev/null",
},
};
@@ -507,7 +508,7 @@ static int dhcp_up(struct interface_defn
return 0;
#endif
return execute("udhcpc -R -n -p /var/run/udhcpc.%iface%.pid "
- "-i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]][[ -t %retries%]]",
+ "-i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]][[ %udhcpc_opts%]]",
ifd, exec);
}
#else
diff -d -urpN busybox.3/networking/udhcp/clientpacket.c busybox.4/networking/udhcp/clientpacket.c
--- busybox.3/networking/udhcp/clientpacket.c 2008-03-31 21:26:05.000000000 +0200
+++ busybox.4/networking/udhcp/clientpacket.c 2008-04-02 01:49:01.000000000 +0200
@@ -62,6 +62,9 @@ static void add_param_req_option(struct
int end = end_option(packet->options);
int i, len = 0;
+ if (client_config.no_default_options)
+ return;
+
packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
if ((dhcp_options[i].flags & OPTION_REQ)
@@ -107,7 +110,9 @@ int send_discover(uint32_t xid, uint32_t
/* Explicitly saying that we want RFC-compliant packets helps
* some buggy DHCP servers to NOT send bigger packets */
add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
+
add_param_req_option(&packet);
+
bb_info_msg("Sending discover...");
return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
@@ -125,8 +130,8 @@ int send_selecting(uint32_t xid, uint32_
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
add_simple_option(packet.options, DHCP_SERVER_ID, server);
-
add_param_req_option(&packet);
+
addr.s_addr = requested;
bb_info_msg("Sending select for %s...", inet_ntoa(addr));
return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
diff -d -urpN busybox.3/networking/udhcp/dhcpc.c busybox.4/networking/udhcp/dhcpc.c
--- busybox.3/networking/udhcp/dhcpc.c 2008-03-31 21:26:05.000000000 +0200
+++ busybox.4/networking/udhcp/dhcpc.c 2008-04-02 01:36:34.000000000 +0200
@@ -182,6 +182,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSE
OPT_W = 1 << 21,
#endif
OPT_P = 1 << 22,
+ OPT_o = 1 << 23,
};
#if ENABLE_GETOPT_LONG
static const char udhcpc_longopts[] ALIGN1 =
@@ -211,6 +212,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSE
#if ENABLE_FEATURE_UDHCP_PORT
"client-port\0" Required_argument "P"
#endif
+ "no-default-options\0" No_argument "o"
;
#endif
/* Default options. */
@@ -230,7 +232,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSE
opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:"
USE_FEATURE_UDHCPC_ARPING("aW:")
USE_FEATURE_UDHCP_PORT("P:")
- "O:"
+ "O:o"
, &str_c, &str_V, &str_h, &str_h, &str_F
, &client_config.interface, &client_config.pidfile, &str_r
, &client_config.script
@@ -291,6 +293,8 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSE
SERVER_PORT = CLIENT_PORT - 1;
}
#endif
+ if (opt & OPT_o)
+ client_config.no_default_options = 1;
while (list_O) {
int n = index_in_strings(dhcp_option_strings, list_O->data);
if (n < 0)
diff -d -urpN busybox.3/networking/udhcp/dhcpc.h busybox.4/networking/udhcp/dhcpc.h
--- busybox.3/networking/udhcp/dhcpc.h 2008-03-31 21:26:05.000000000 +0200
+++ busybox.4/networking/udhcp/dhcpc.h 2008-04-02 01:36:48.000000000 +0200
@@ -21,6 +21,7 @@ struct client_config_t {
char release_on_quit; /* Perform release on quit */
char abort_if_no_lease; /* Abort if no lease */
char background_if_no_lease; /* Fork to background if no lease */
+ char no_default_options; /* Do not include default optins in request */
const char *interface; /* The name of the interface to use */
char *pidfile; /* Optionally store the process ID */
const char *script; /* User script to run at dhcp events */
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