Code based on networking/zcip.c in busybox commit 8531d76a15890c2c535908ce888b2e2aed35b172 Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>master
Joe Hershberger
12 years ago
parent
228041893c
commit
d22c338e07
@ -0,0 +1,76 @@ |
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------------------------------------------ |
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Link-local IP address auto-configuration |
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------------------------------------------ |
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|
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Negotiate with other link-local clients on the local network |
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for an address that doesn't require explicit configuration. |
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This is especially useful if a DHCP server cannot be guaranteed |
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to exist in all environments that the device must operate. |
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|
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This is an implementation of RFC3927. |
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---------- |
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Commands |
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---------- |
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|
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When CONFIG_CMD_LINK_LOCAL is defined in the board config file, |
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the "linklocal" command is available. This running this will |
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take approximately 5 seconds while the address is negotiated. |
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|
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------------------------ |
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Environment interation |
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------------------------ |
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The "llipaddr" variable is set with the most recently |
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negotiated address and is preferred in future negotiations. |
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The "ipaddr", "netmask", and "gatewayip" variables are set |
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after successful negotiation to enable network access. |
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|
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------------- |
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Limitations |
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------------- |
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|
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RFC3927 requires that addresses are continuously checked to |
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avoid conflicts, however this can only happen when the NetLoop |
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is getting called. It is possible for a conflict to go undetected |
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until a command that accesses the network is executed. |
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|
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Using NetConsole is one way to ensure that NetLoop is always |
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processing packets and monitoring for conflicts. |
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This is also not a concern if the feature is use to connect |
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directly to another machine that may not be running a DHCP server. |
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|
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---------------- |
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Example script |
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---------------- |
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|
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This script allows use of DHCP and/or Link-local controlled |
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by env variables. It depends on CONFIG_CMD_LINK_LOCAL, CONFIG_CMD_DHCP, |
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and CONFIG_BOOTP_MAY_FAIL. |
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If both fail or are disabled, static settings are used. |
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|
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#define CONFIG_EXTRA_ENV_SETTINGS \ |
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"ipconfigcmd=if test \\\"$dhcpenabled\\\" -ne 0;" \ |
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"then " \ |
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"dhcpfail=0;dhcp || dhcpfail=1;" \ |
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"else " \ |
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"dhcpfail=-1;" \ |
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"fi;" \ |
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"if test \\\"$linklocalenabled\\\" -ne 0 -a " \ |
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"\\\"$dhcpfail\\\" -ne 0;" \ |
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"then " \ |
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"linklocal;" \ |
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"llfail=0;" \ |
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"else " \ |
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"llfail=-1;" \ |
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"fi;" \ |
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"if test \\\"$llfail\\\" -ne 0 -a " \ |
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"\\\"$dhcpfail\\\" -ne 0; " \ |
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"then " \ |
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"setenv ipaddr $sipaddr; " \ |
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"setenv netmask $snetmask; " \ |
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"setenv gatewayip $sgatewayip; " \ |
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"fi;\0" \ |
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@ -0,0 +1,332 @@ |
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/*
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* RFC3927 ZeroConf IPv4 Link-Local addressing |
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* (see <http://www.zeroconf.org/>)
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* |
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* Copied from BusyBox - networking/zcip.c |
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* |
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* Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com) |
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* Copyright (C) 2004 by David Brownell |
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* Copyright (C) 2010 by Joe Hershberger |
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* |
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* Licensed under the GPL v2 or later |
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*/ |
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|
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#include <common.h> |
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#include <net.h> |
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#include "arp.h" |
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#include "net_rand.h" |
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/* We don't need more than 32 bits of the counter */ |
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#define MONOTONIC_MS() ((unsigned)get_timer(0) * (1000 / CONFIG_SYS_HZ)) |
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enum { |
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/* 169.254.0.0 */ |
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LINKLOCAL_ADDR = 0xa9fe0000, |
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IN_CLASSB_NET = 0xffff0000, |
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IN_CLASSB_HOST = 0x0000ffff, |
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|
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/* protocol timeout parameters, specified in seconds */ |
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PROBE_WAIT = 1, |
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PROBE_MIN = 1, |
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PROBE_MAX = 2, |
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PROBE_NUM = 3, |
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MAX_CONFLICTS = 10, |
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RATE_LIMIT_INTERVAL = 60, |
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ANNOUNCE_WAIT = 2, |
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ANNOUNCE_NUM = 2, |
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ANNOUNCE_INTERVAL = 2, |
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DEFEND_INTERVAL = 10 |
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}; |
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|
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/* States during the configuration process. */ |
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static enum ll_state_t { |
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PROBE = 0, |
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RATE_LIMIT_PROBE, |
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ANNOUNCE, |
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MONITOR, |
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DEFEND, |
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DISABLED |
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} state = DISABLED; |
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static IPaddr_t ip; |
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static int timeout_ms = -1; |
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static unsigned deadline_ms; |
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static unsigned conflicts; |
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static unsigned nprobes; |
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static unsigned nclaims; |
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static int ready; |
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static void link_local_timeout(void); |
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/**
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* Pick a random link local IP address on 169.254/16, except that |
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* the first and last 256 addresses are reserved. |
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*/ |
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static IPaddr_t pick(void) |
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{ |
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unsigned tmp; |
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do { |
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tmp = rand() & IN_CLASSB_HOST; |
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} while (tmp > (IN_CLASSB_HOST - 0x0200)); |
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return (IPaddr_t) htonl((LINKLOCAL_ADDR + 0x0100) + tmp); |
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} |
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/**
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* Return milliseconds of random delay, up to "secs" seconds. |
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*/ |
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static inline unsigned random_delay_ms(unsigned secs) |
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{ |
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return rand() % (secs * 1000); |
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} |
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static void configure_wait(void) |
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{ |
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if (timeout_ms == -1) |
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return; |
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/* poll, being ready to adjust current timeout */ |
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if (!timeout_ms) |
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timeout_ms = random_delay_ms(PROBE_WAIT); |
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/* set deadline_ms to the point in time when we timeout */ |
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deadline_ms = MONOTONIC_MS() + timeout_ms; |
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debug("...wait %d %s nprobes=%u, nclaims=%u\n", |
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timeout_ms, eth_get_name(), nprobes, nclaims); |
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NetSetTimeout(timeout_ms, link_local_timeout); |
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} |
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void link_local_start(void) |
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{ |
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ip = getenv_IPaddr("llipaddr"); |
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if (ip != 0 && (ip & IN_CLASSB_NET) != LINKLOCAL_ADDR) { |
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puts("invalid link address"); |
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net_set_state(NETLOOP_FAIL); |
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return; |
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} |
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NetOurSubnetMask = IN_CLASSB_NET; |
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srand_mac(); |
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if (ip == 0) |
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ip = pick(); |
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state = PROBE; |
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timeout_ms = 0; |
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conflicts = 0; |
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nprobes = 0; |
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nclaims = 0; |
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ready = 0; |
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configure_wait(); |
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} |
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static void link_local_timeout(void) |
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{ |
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switch (state) { |
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case PROBE: |
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/* timeouts in the PROBE state mean no conflicting ARP packets
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have been received, so we can progress through the states */ |
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if (nprobes < PROBE_NUM) { |
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nprobes++; |
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debug("probe/%u %s@%pI4\n", |
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nprobes, eth_get_name(), &ip); |
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arp_raw_request(0, NetEtherNullAddr, ip); |
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timeout_ms = PROBE_MIN * 1000; |
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timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN); |
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} else { |
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/* Switch to announce state */ |
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state = ANNOUNCE; |
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nclaims = 0; |
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debug("announce/%u %s@%pI4\n", |
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nclaims, eth_get_name(), &ip); |
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arp_raw_request(ip, NetOurEther, ip); |
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timeout_ms = ANNOUNCE_INTERVAL * 1000; |
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} |
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break; |
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case RATE_LIMIT_PROBE: |
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/* timeouts in the RATE_LIMIT_PROBE state mean no conflicting
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ARP packets have been received, so we can move immediately |
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to the announce state */ |
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state = ANNOUNCE; |
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nclaims = 0; |
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debug("announce/%u %s@%pI4\n", |
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nclaims, eth_get_name(), &ip); |
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arp_raw_request(ip, NetOurEther, ip); |
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timeout_ms = ANNOUNCE_INTERVAL * 1000; |
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break; |
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case ANNOUNCE: |
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/* timeouts in the ANNOUNCE state mean no conflicting ARP
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packets have been received, so we can progress through |
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the states */ |
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if (nclaims < ANNOUNCE_NUM) { |
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nclaims++; |
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debug("announce/%u %s@%pI4\n", |
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nclaims, eth_get_name(), &ip); |
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arp_raw_request(ip, NetOurEther, ip); |
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timeout_ms = ANNOUNCE_INTERVAL * 1000; |
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} else { |
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/* Switch to monitor state */ |
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state = MONITOR; |
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printf("Successfully assigned %pI4\n", &ip); |
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NetCopyIP(&NetOurIP, &ip); |
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ready = 1; |
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conflicts = 0; |
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timeout_ms = -1; |
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/* Never timeout in the monitor state */ |
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NetSetTimeout(0, NULL); |
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/* NOTE: all other exit paths should deconfig ... */ |
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net_set_state(NETLOOP_SUCCESS); |
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return; |
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} |
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break; |
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case DEFEND: |
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/* We won! No ARP replies, so just go back to monitor */ |
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state = MONITOR; |
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timeout_ms = -1; |
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conflicts = 0; |
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break; |
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default: |
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/* Invalid, should never happen. Restart the whole protocol */ |
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state = PROBE; |
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ip = pick(); |
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timeout_ms = 0; |
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nprobes = 0; |
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nclaims = 0; |
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break; |
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} |
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configure_wait(); |
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} |
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void link_local_receive_arp(struct arp_hdr *arp, int len) |
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{ |
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int source_ip_conflict; |
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int target_ip_conflict; |
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if (state == DISABLED) |
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return; |
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/* We need to adjust the timeout in case we didn't receive a
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conflicting packet. */ |
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if (timeout_ms > 0) { |
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unsigned diff = deadline_ms - MONOTONIC_MS(); |
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if ((int)(diff) < 0) { |
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/* Current time is greater than the expected timeout
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time. This should never happen */ |
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debug("missed an expected timeout\n"); |
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timeout_ms = 0; |
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} else { |
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debug("adjusting timeout\n"); |
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timeout_ms = diff | 1; /* never 0 */ |
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} |
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} |
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/*
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* XXX Don't bother with ethernet link just yet |
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if ((fds[0].revents & POLLIN) == 0) { |
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if (fds[0].revents & POLLERR) { |
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// FIXME: links routinely go down;
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// this shouldn't necessarily exit.
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bb_error_msg("iface %s is down", eth_get_name()); |
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if (ready) { |
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run(argv, "deconfig", &ip); |
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} |
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return EXIT_FAILURE; |
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} |
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continue; |
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} |
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*/ |
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debug("%s recv arp type=%d, op=%d,\n", |
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eth_get_name(), ntohs(arp->ar_pro), |
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ntohs(arp->ar_op)); |
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debug("\tsource=%pM %pI4\n", |
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&arp->ar_sha, |
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&arp->ar_spa); |
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debug("\ttarget=%pM %pI4\n", |
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&arp->ar_tha, |
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&arp->ar_tpa); |
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if (arp->ar_op != htons(ARPOP_REQUEST) |
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&& arp->ar_op != htons(ARPOP_REPLY) |
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) { |
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configure_wait(); |
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return; |
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} |
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source_ip_conflict = 0; |
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target_ip_conflict = 0; |
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if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0 |
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&& memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0 |
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) { |
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source_ip_conflict = 1; |
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} |
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if (arp->ar_op == htons(ARPOP_REQUEST) |
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&& memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0 |
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&& memcmp(&arp->ar_tha, NetOurEther, ARP_HLEN) != 0 |
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) { |
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target_ip_conflict = 1; |
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} |
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debug("state = %d, source ip conflict = %d, target ip conflict = %d\n", |
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state, source_ip_conflict, target_ip_conflict); |
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switch (state) { |
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case PROBE: |
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case ANNOUNCE: |
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/* When probing or announcing, check for source IP conflicts
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and other hosts doing ARP probes (target IP conflicts). */ |
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if (source_ip_conflict || target_ip_conflict) { |
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conflicts++; |
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state = PROBE; |
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if (conflicts >= MAX_CONFLICTS) { |
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debug("%s ratelimit\n", eth_get_name()); |
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timeout_ms = RATE_LIMIT_INTERVAL * 1000; |
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state = RATE_LIMIT_PROBE; |
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} |
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/* restart the whole protocol */ |
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ip = pick(); |
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timeout_ms = 0; |
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nprobes = 0; |
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nclaims = 0; |
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} |
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break; |
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case MONITOR: |
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/* If a conflict, we try to defend with a single ARP probe */ |
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if (source_ip_conflict) { |
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debug("monitor conflict -- defending\n"); |
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state = DEFEND; |
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timeout_ms = DEFEND_INTERVAL * 1000; |
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arp_raw_request(ip, NetOurEther, ip); |
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} |
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break; |
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case DEFEND: |
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/* Well, we tried. Start over (on conflict) */ |
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if (source_ip_conflict) { |
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state = PROBE; |
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debug("defend conflict -- starting over\n"); |
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ready = 0; |
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NetOurIP = 0; |
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/* restart the whole protocol */ |
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ip = pick(); |
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timeout_ms = 0; |
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nprobes = 0; |
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nclaims = 0; |
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} |
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break; |
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default: |
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/* Invalid, should never happen. Restart the whole protocol */ |
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debug("invalid state -- starting over\n"); |
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state = PROBE; |
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ip = pick(); |
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timeout_ms = 0; |
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nprobes = 0; |
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nclaims = 0; |
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break; |
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} |
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configure_wait(); |
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} |
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@ -0,0 +1,24 @@ |
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/*
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* RFC3927 ZeroConf IPv4 Link-Local addressing |
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* (see <http://www.zeroconf.org/>)
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* |
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* Copied from BusyBox - networking/zcip.c |
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* |
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* Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com) |
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* Copyright (C) 2004 by David Brownell |
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* |
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* Licensed under the GPL v2 or later |
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*/ |
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#if defined(CONFIG_CMD_LINK_LOCAL) |
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#ifndef __LINK_LOCAL_H__ |
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#define __LINK_LOCAL_H__ |
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#include <common.h> |
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void link_local_receive_arp(struct arp_hdr *arp, int len); |
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void link_local_start(void); |
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#endif /* __LINK_LOCAL_H__ */ |
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#endif |
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