[PATCH] add IP check functionality to udhcpc
Jonas Danielsson
jonas.danielsson at axis.com
Thu Nov 22 01:45:22 PST 2007
Hi again vda,
I'm attaching a small patch that fixes the Kbuild-file from your patch.
-Jonas
Jonas Danielsson wrote:
> Denys Vlasenko wrote:
>
>> Had to edit it quite a bit. You added #include's which were not needed.
>> You removed memcmp without explaining why.
>> send_decline()'s stype was different from surrounding code.
>>
>> +static int arpcheck = 0;
>> +static int decline_wait = 10;
>>
>> These statics are not needed, local variables will work as well.
>>
>> I fixed these things, and possibly added my own bugs ;)
>>
>> Please test attached patch, is it still doing what you need?
>>
>> Question: do you really need "-W seconds"?
>> Why not reuse "-A seconds" value?
>> --
>> vda
>>
>>
>>
> Hi vda,
>
> The patch still does what I need. Thanks alot for your comments and
> modifications!
> But I had problems building it at first. Could you explain to me what
> this snippet does?
>
> UDHCPC_NEEDS_ARPING-$(CONFIG_FEATURE_UDHCPC_ARPING) = y
> lib-$(UDHCPC_NEEDS_ARPING) += arpping.o
>
> The build process failed to link in arpping.o for me so I had to work
> around it to make it
> compile. I can't find any other references to UDHCPC_NEEDS_ARPING in the
> codebase.
>
> About the -W seconds. I added it because of what was pointed out in the
> RFC2131:
>
> 5. The client receives the DHCPACK message with configuration
> parameters. The client SHOULD perform a final check on the
> parameters (e.g., ARP for allocated network address), and notes the
> duration of the lease specified in the DHCPACK message. At this
> point, the client is configured. If the client detects that the
> address is already in use (e.g., through the use of ARP), the
> client MUST send a DHCPDECLINE message to the server and restarts
> the configuration process. The client SHOULD wait a minimum of ten
> seconds before restarting the configuration process to avoid
> excessive network traffic in case of looping.
>
>
> It is the matter of the minimum of 10 seconds that made me include it.
> But maybe it is better to reuse the --tryagain flag
> and set a lower bound on it?
>
> - Jonas
>
>
>
>> ------------------------------------------------------------------------
>>
>> diff -d -urpN busybox.1/include/usage.h busybox.2/include/usage.h
>> --- busybox.1/include/usage.h 2007-11-17 19:56:45.000000000 -0800
>> +++ busybox.2/include/usage.h 2007-11-21 14:28:52.000000000 -0800
>> @@ -2183,8 +2183,8 @@
>> "and * (run both after creating and before deleting). The commands run in\n" \
>> "the /dev directory, and use system() which calls /bin/sh.\n\n" \
>> ) \
>> - "Config file parsing stops on the first matching line. If no config\n"\
>> - "entry is matched, devices are created with default 0:0 660. (Make\n"\
>> + "Config file parsing stops on the first matching line. If no config\n" \
>> + "entry is matched, devices are created with default 0:0 660. (Make\n" \
>> "the last line match .* to override this.)\n\n" \
>> )
>>
>> @@ -3843,44 +3843,50 @@ USE_FEATURE_RUN_PARTS_FANCY("\n -l Print
>> " [-p pidfile] [-r IP] [-s script]"
>> #define udhcpc_full_usage \
>> USE_GETOPT_LONG( \
>> - " -V,--vendorclass=CLASSID Set vendor class identifier" \
>> - "\n -i,--interface=INTERFACE Interface to use (default: eth0)" \
>> + " -V,--vendorclass=CLASSID Vendor class identifier" \
>> + "\n -i,--interface=INTERFACE Interface to use (default eth0)" \
>> "\n -H,-h,--hostname=HOSTNAME Client hostname" \
>> - "\n -c,--clientid=CLIENTID Set client identifier" \
>> + "\n -c,--clientid=CLIENTID Client identifier" \
>> "\n -C,--clientid-none Suppress default client identifier" \
>> - "\n -p,--pidfile=file Store process ID of daemon in file" \
>> + "\n -p,--pidfile=file Create pidfile" \
>> "\n -r,--request=IP IP address to request" \
>> "\n -s,--script=file Run file at dhcp events (default: /usr/share/udhcpc/default.script)" \
>> - "\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: 60) after failure"\
>> + "\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 60) after failure" \
>> "\n -f,--foreground Run in foreground" \
>> - "\n -b,--background Background if lease cannot be immediately negotiated" \
>> + "\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 cannot be immediately negotiated" \
>> + "\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 -v,--version Display version" \
>> + USE_FEATURE_UDHCPC_ARPING( \
>> + "\n -a,--arping Use arping to validate offered address" \
>> + "\n -W,--wait=N Wait N seconds after declining (default 10)" \
>> + ) \
>> ) \
>> SKIP_GETOPT_LONG( \
>> - " -V CLASSID Set vendor class identifier" \
>> + " -V CLASSID Vendor class identifier" \
>> "\n -i INTERFACE Interface to use (default: eth0)" \
>> "\n -H,-h HOSTNAME Client hostname" \
>> - "\n -c CLIENTID Set client identifier" \
>> + "\n -c CLIENTID Client identifier" \
>> "\n -C Suppress default client identifier" \
>> - "\n -p file Store process ID of daemon in file" \
>> + "\n -p file Create pidfile" \
>> "\n -r IP IP address to request" \
>> "\n -s file Run file at dhcp events (default: /usr/share/udhcpc/default.script)" \
>> - "\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: 60) after failure"\
>> + "\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 60) after failure" \
>> "\n -f Run in foreground" \
>> - "\n -b Background if lease cannot be immediately negotiated" \
>> + "\n -b Background if lease is not immediately obtained" \
>> "\n -S Log to syslog too" \
>> - "\n -n Exit with failure if lease cannot be immediately negotiated" \
>> + "\n -n Exit with failure if lease is not immediately obtained" \
>> "\n -q Quit after obtaining lease" \
>> "\n -R Release IP on quit" \
>> - "\n -v Display version" \
>> + USE_FEATURE_UDHCPC_ARPING( \
>> + "\n -a Use arping to validate offered address" \
>> + "\n -W N Wait N seconds after declining (default 10)" \
>> + ) \
>> )
>>
>> #define udhcpd_trivial_usage \
>> diff -d -urpN busybox.1/networking/udhcp/Config.in busybox.2/networking/udhcp/Config.in
>> --- busybox.1/networking/udhcp/Config.in 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/Config.in 2007-11-21 13:12:36.000000000 -0800
>> @@ -54,6 +54,16 @@ config APP_UDHCPC
>>
>> See http://udhcp.busybox.net for further details.
>>
>> +config FEATURE_UDHCPC_ARPING
>> + bool "Ask udhcpc to verify that the offered address is free, using arpping"
>> + default y
>> + depends on APP_UDHCPC
>> + help
>> + If selected, udhcpc will use arpping to make sure the offered address
>> + is really available. The client will DHCPDECLINE the offer if the
>> + address is in use, and restart the discover process.
>> +
>> +
>> config FEATURE_UDHCP_DEBUG
>> bool "Compile udhcp with noisy debugging messages"
>> default n
>> diff -d -urpN busybox.1/networking/udhcp/Kbuild busybox.2/networking/udhcp/Kbuild
>> --- busybox.1/networking/udhcp/Kbuild 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/Kbuild 2007-11-21 13:57:24.000000000 -0800
>> @@ -10,10 +10,16 @@ lib-$(CONFIG_APP_UDHCPC) += commo
>> signalpipe.o socket.o
>> lib-$(CONFIG_APP_UDHCPD) += common.o options.o packet.o \
>> signalpipe.o socket.o
>> +
>> lib-$(CONFIG_APP_UDHCPC) += dhcpc.o clientpacket.o clientsocket.o \
>> script.o
>> +
>> +UDHCPC_NEEDS_ARPING-$(CONFIG_FEATURE_UDHCPC_ARPING) = y
>> +lib-$(UDHCPC_NEEDS_ARPING) += arpping.o
>> +
>> lib-$(CONFIG_APP_UDHCPD) += dhcpd.o arpping.o files.o leases.o \
>> serverpacket.o static_leases.o
>> +
>> lib-$(CONFIG_APP_DUMPLEASES) += dumpleases.o
>> lib-$(CONFIG_APP_DHCPRELAY) += dhcprelay.o
>> lib-$(CONFIG_FEATURE_RFC3397) += domain_codec.o
>> diff -d -urpN busybox.1/networking/udhcp/arpping.c busybox.2/networking/udhcp/arpping.c
>> --- busybox.1/networking/udhcp/arpping.c 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/arpping.c 2007-11-21 14:29:30.000000000 -0800
>> @@ -32,12 +32,16 @@ struct arpMsg {
>> uint8_t pad[18]; /* 2a pad for min. ethernet payload (60 bytes) */
>> } ATTRIBUTE_PACKED;
>>
>> +enum {
>> + ARP_MSG_SIZE = 0x2a
>> +};
>> +
>>
>> /* Returns 1 if no reply received */
>>
>> int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface)
>> {
>> - int timeout_ms = 2000;
>> + int timeout_ms;
>> struct pollfd pfd[1];
>> #define s (pfd[0].fd) /* socket */
>> int rv = 1; /* "no reply received" yet */
>> @@ -51,7 +55,7 @@ int arpping(uint32_t test_ip, uint32_t f
>> }
>>
>> if (setsockopt_broadcast(s) == -1) {
>> - bb_perror_msg("cannot setsocketopt on raw socket");
>> + bb_perror_msg("cannot enable bcast on raw socket");
>> goto ret;
>> }
>>
>> @@ -67,28 +71,35 @@ int arpping(uint32_t test_ip, uint32_t f
>> arp.operation = htons(ARPOP_REQUEST); /* ARP op code */
>> memcpy(arp.sHaddr, from_mac, 6); /* source hardware address */
>> memcpy(arp.sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */
>> - /* tHaddr */ /* target hardware address */
>> + /* tHaddr is zero-fiiled */ /* target hardware address */
>> memcpy(arp.tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */
>>
>> memset(&addr, 0, sizeof(addr));
>> safe_strncpy(addr.sa_data, interface, sizeof(addr.sa_data));
>> - if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
>> + if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0) {
>> + // TODO: error message? caller didn't expect us to fail,
>> + // just returning 1 "no reply received" misleads it.
>> goto ret;
>> + }
>>
>> /* wait for arp reply, and check it */
>> + timeout_ms = 2000;
>> do {
>> int r;
>> unsigned prevTime = monotonic_us();
>>
>> pfd[0].events = POLLIN;
>> r = safe_poll(pfd, 1, timeout_ms);
>> - if (r < 0) {
>> + if (r < 0)
>> break;
>> - } else if (r) {
>> - if (read(s, &arp, sizeof(arp)) < 0)
>> + if (r) {
>> + r = read(s, &arp, sizeof(arp));
>> + if (r < 0)
>> break;
>> - if (arp.operation == htons(ARPOP_REPLY)
>> - && memcmp(arp.tHaddr, from_mac, 6) == 0
>> + if (r >= ARP_MSG_SIZE
>> + && arp.operation == htons(ARPOP_REPLY)
>> + /* don't check it: Linux doesn't return proper tHaddr (fixed in 2.6.24?) */
>> + /* && memcmp(arp.tHaddr, from_mac, 6) == 0 */
>> && *((uint32_t *) arp.sInaddr) == test_ip
>> ) {
>> rv = 0;
>> diff -d -urpN busybox.1/networking/udhcp/clientpacket.c busybox.2/networking/udhcp/clientpacket.c
>> --- busybox.1/networking/udhcp/clientpacket.c 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/clientpacket.c 2007-11-21 13:59:30.000000000 -0800
>> @@ -69,6 +69,22 @@ static void add_requests(struct dhcpMess
>>
>> }
>>
>> +#if ENABLE_FEATURE_UDHCPC_ARPING
>> +/* Unicast a DHCP decline message */
>> +int send_decline(uint32_t xid, uint32_t server)
>> +{
>> + struct dhcpMessage packet;
>> +
>> + init_packet(&packet, DHCPDECLINE);
>> + packet.xid = xid;
>> + add_requests(&packet);
>> +
>> + bb_info_msg("Sending decline...");
>> +
>> + return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
>> + SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
>> +}
>> +#endif
>>
>> /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
>> int send_discover(uint32_t xid, uint32_t requested)
>> diff -d -urpN busybox.1/networking/udhcp/common.h busybox.2/networking/udhcp/common.h
>> --- busybox.1/networking/udhcp/common.h 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/common.h 2007-11-21 13:32:30.000000000 -0800
>> @@ -76,7 +76,7 @@ void udhcp_run_script(struct dhcpMessage
>>
>> void udhcp_sp_setup(void);
>> int udhcp_sp_fd_set(fd_set *rfds, int extra_fd);
>> -int udhcp_sp_read(fd_set *rfds);
>> +int udhcp_sp_read(const fd_set *rfds);
>> int raw_socket(int ifindex);
>> int read_interface(const char *interface, int *ifindex, uint32_t *addr, uint8_t *arp);
>> int listen_socket(/*uint32_t ip,*/ int port, const char *inf);
>> diff -d -urpN busybox.1/networking/udhcp/dhcpc.c busybox.2/networking/udhcp/dhcpc.c
>> --- busybox.1/networking/udhcp/dhcpc.c 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/dhcpc.c 2007-11-21 14:27:41.000000000 -0800
>> @@ -145,6 +145,13 @@ int udhcpc_main(int argc, char **argv)
>> {
>> uint8_t *temp, *message;
>> char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_A, *str_t;
>> + int tryagain_timeout = 60;
>> + int discover_timeout = 3;
>> + int discover_retries = 3;
>> +#if ENABLE_FEATURE_UDHCPC_ARPING
>> + int decline_wait = 10;
>> + char *str_W;
>> +#endif
>> uint32_t xid = 0;
>> uint32_t lease = 0; /* can be given as 32-bit quantity */
>> unsigned t1 = 0, t2 = 0; /* what a wonderful names */
>> @@ -180,6 +187,10 @@ int udhcpc_main(int argc, char **argv)
>> OPT_v = 1 << 17,
>> OPT_S = 1 << 18,
>> OPT_A = 1 << 19,
>> +#if ENABLE_FEATURE_UDHCPC_ARPING
>> + OPT_a = 1 << 20,
>> + OPT_W = 1 << 21,
>> +#endif
>> };
>> #if ENABLE_GETOPT_LONG
>> static const char udhcpc_longopts[] ALIGN1 =
>> @@ -203,14 +214,15 @@ int udhcpc_main(int argc, char **argv)
>> "retries\0" Required_argument "t"
>> "tryagain\0" Required_argument "A"
>> "syslog\0" No_argument "S"
>> +#if ENABLE_FEATURE_UDHCPC_ARPING
>> + "arping\0" No_argument "a"
>> + "wait\0" Required_argument "W"
>> +#endif
>> ;
>> #endif
>> /* Default options. */
>> client_config.interface = "eth0";
>> client_config.script = DEFAULT_SCRIPT;
>> - client_config.retries = 3;
>> - client_config.timeout = 3;
>> - client_config.tryagain = 60;
>>
>> /* Parse command line */
>> opt_complementary = "c--C:C--c" // mutually exclusive
>> @@ -218,10 +230,12 @@ int udhcpc_main(int argc, char **argv)
>> #if ENABLE_GETOPT_LONG
>> applet_long_options = udhcpc_longopts;
>> #endif
>> - opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:",
>> - &str_c, &str_V, &str_h, &str_h, &str_F,
>> + opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:"
>> + USE_FEATURE_UDHCPC_ARPING("aW:")
>> + , &str_c, &str_V, &str_h, &str_h, &str_F,
>> &client_config.interface, &client_config.pidfile, &str_r,
>> &client_config.script, &str_T, &str_t, &str_A
>> + USE_FEATURE_UDHCPC_ARPING(, &str_W)
>> );
>>
>> if (opt & OPT_c)
>> @@ -259,11 +273,11 @@ int udhcpc_main(int argc, char **argv)
>> requested_ip = inet_addr(str_r);
>> // if (opt & OPT_s) client_config.script = ...
>> if (opt & OPT_T)
>> - client_config.timeout = xatoi_u(str_T);
>> + discover_timeout = xatoi_u(str_T);
>> if (opt & OPT_t)
>> - client_config.retries = xatoi_u(str_t);
>> + discover_retries = xatoi_u(str_t);
>> if (opt & OPT_A)
>> - client_config.tryagain = xatoi_u(str_A);
>> + tryagain_timeout = xatoi_u(str_A);
>> if (opt & OPT_v) {
>> puts("version "BB_VER);
>> return 0;
>> @@ -274,6 +288,11 @@ int udhcpc_main(int argc, char **argv)
>> logmode |= LOGMODE_SYSLOG;
>> }
>>
>> +#if ENABLE_FEATURE_UDHCPC_ARPING
>> + if (opt & OPT_W)
>> + decline_wait = xatou_range(str_W, 10, INT_MAX);
>> +#endif
>> +
>> if (read_interface(client_config.interface, &client_config.ifindex,
>> NULL, client_config.arp))
>> return 1;
>> @@ -339,14 +358,14 @@ int udhcpc_main(int argc, char **argv)
>> /* timeout dropped to zero */
>> switch (state) {
>> case INIT_SELECTING:
>> - if (packet_num < client_config.retries) {
>> + if (packet_num < discover_retries) {
>> if (packet_num == 0)
>> xid = random_xid();
>>
>> /* send discover packet */
>> send_discover(xid, requested_ip); /* broadcast */
>>
>> - timeout = now + client_config.timeout;
>> + timeout = now + discover_timeout;
>> packet_num++;
>> } else {
>> udhcp_run_script(NULL, "leasefail");
>> @@ -360,12 +379,12 @@ int udhcpc_main(int argc, char **argv)
>> }
>> /* wait to try again */
>> packet_num = 0;
>> - timeout = now + client_config.tryagain;
>> + timeout = now + tryagain_timeout;
>> }
>> break;
>> case RENEW_REQUESTED:
>> case REQUESTING:
>> - if (packet_num < client_config.retries) {
>> + if (packet_num < discover_retries) {
>> /* send request packet */
>> if (state == RENEW_REQUESTED)
>> send_renew(xid, server_addr, requested_ip); /* unicast */
>> @@ -491,6 +510,29 @@ int udhcpc_main(int argc, char **argv)
>> lease = ntohl(lease);
>> }
>>
>> +#if ENABLE_FEATURE_UDHCPC_ARPING
>> + if (opt & OPT_a) {
>> + if (!arpping(packet.yiaddr,
>> + (uint32_t) 0,
>> + client_config.arp,
>> + client_config.interface)
>> + ) {
>> + bb_info_msg("offered address is in use,"
>> + " declining");
>> + send_decline(xid, server_addr);
>> +
>> + if (state != REQUESTING)
>> + udhcp_run_script(NULL, "deconfig");
>> + state = INIT_SELECTING;
>> + timeout = now;
>> + requested_ip = 0;
>> + packet_num = 0;
>> + change_mode(LISTEN_RAW);
>> + sleep(decline_wait); /* avoid excessive network traffic */
>> + break;
>> + }
>> + }
>> +#endif
>> /* enter bound state */
>> t1 = lease / 2;
>>
>> diff -d -urpN busybox.1/networking/udhcp/dhcpc.h busybox.2/networking/udhcp/dhcpc.h
>> --- busybox.1/networking/udhcp/dhcpc.h 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/dhcpc.h 2007-11-21 14:24:23.000000000 -0800
>> @@ -1,5 +1,6 @@
>> /* vi: set sw=4 ts=4: */
>> /* dhcpc.h */
>> +
>> #ifndef _DHCPC_H
>> #define _DHCPC_H
>>
>> @@ -28,9 +29,6 @@ struct client_config_t {
>> uint8_t *hostname; /* Optional hostname to use */
>> uint8_t *fqdn; /* Optional fully qualified domain name to use */
>> int ifindex; /* Index number of the interface to use */
>> - int retries; /* Max number of request packets */
>> - int timeout; /* Number of seconds to try to get a lease */
>> - int tryagain; /* Number of seconds to try to get a lease */
>> uint8_t arp[6]; /* Our arp address */
>> };
>>
>> @@ -42,6 +40,9 @@ struct client_config_t {
>> uint32_t random_xid(void);
>> int send_discover(uint32_t xid, uint32_t requested);
>> int send_selecting(uint32_t xid, uint32_t server, uint32_t requested);
>> +#if ENABLE_FEATURE_UDHCPC_ARPING
>> +int send_decline(uint32_t xid, uint32_t server);
>> +#endif
>> int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr);
>> int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr);
>> int send_release(uint32_t server, uint32_t ciaddr);
>> diff -d -urpN busybox.1/networking/udhcp/signalpipe.c busybox.2/networking/udhcp/signalpipe.c
>> --- busybox.1/networking/udhcp/signalpipe.c 2007-11-15 21:02:19.000000000 -0800
>> +++ busybox.2/networking/udhcp/signalpipe.c 2007-11-21 13:32:23.000000000 -0800
>> @@ -66,7 +66,7 @@ int udhcp_sp_fd_set(fd_set *rfds, int ex
>> /* Read a signal from the signal pipe. Returns 0 if there is
>> * no signal, -1 on error (and sets errno appropriately), and
>> * your signal on success */
>> -int udhcp_sp_read(fd_set *rfds)
>> +int udhcp_sp_read(const fd_set *rfds)
>> {
>> unsigned char sig;
>>
>>
>>
>
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