Code based on networking/zcip.c in busybox commit 8531d76a15890c2c535908ce888b2e2aed35b172
Signed-off-by: Joe Hershberger joe.hershberger@ni.com Cc: Joe Hershberger joe.hershberger@gmail.com --- Changes for v2: - Omitted unrelated whitespace changes - Made do_link_local() static - Pushed #ifdef CONFIG_CMD_LINK_LOCAL into header Changes for v3: - Rebased onto other changed patches
README | 10 ++ common/cmd_net.c | 31 +++++ doc/README.link-local | 76 +++++++++++ include/net.h | 2 +- net/Makefile | 4 +- net/link_local.c | 332 +++++++++++++++++++++++++++++++++++++++++++++++++ net/link_local.h | 24 ++++ net/net.c | 13 ++ 8 files changed, 490 insertions(+), 2 deletions(-) create mode 100644 doc/README.link-local create mode 100644 net/link_local.c create mode 100644 net/link_local.h
diff --git a/README b/README index 6e313ad..67dc444 100644 --- a/README +++ b/README @@ -785,6 +785,8 @@ The following options need to be configured: CONFIG_CMD_JFFS2 * JFFS2 Support CONFIG_CMD_KGDB * kgdb CONFIG_CMD_LDRINFO ldrinfo (display Blackfin loader) + CONFIG_CMD_LINK_LOCAL * link-local IP address auto-configuration + (169.254.*.*) CONFIG_CMD_LOADB loadb CONFIG_CMD_LOADS loads CONFIG_CMD_MD5SUM print md5 message digest @@ -1633,6 +1635,14 @@ The following options need to be configured: the DHCP timeout and retry process takes a longer than this delay.
+ - Link-local IP address negotiation: + Negotiate with other link-local clients on the local network + for an address that doesn't require explicit configuration. + This is especially useful if a DHCP server cannot be guaranteed + to exist in all environments that the device must operate. + + See doc/README.link-local for more information. + - CDP Options: CONFIG_CDP_DEVICE_ID
diff --git a/common/cmd_net.c b/common/cmd_net.c index 2f66056..a9ade8b 100644 --- a/common/cmd_net.c +++ b/common/cmd_net.c @@ -428,3 +428,34 @@ U_BOOT_CMD( );
#endif /* CONFIG_CMD_DNS */ + +#if defined(CONFIG_CMD_LINK_LOCAL) +static int do_link_local(cmd_tbl_t *cmdtp, int flag, int argc, + char * const argv[]) +{ + char tmp[22]; + + if (NetLoop(LINKLOCAL) < 0) + return 1; + + NetOurGatewayIP = 0; + ip_to_string(NetOurGatewayIP, tmp); + setenv("gatewayip", tmp); + + ip_to_string(NetOurSubnetMask, tmp); + setenv("netmask", tmp); + + ip_to_string(NetOurIP, tmp); + setenv("ipaddr", tmp); + setenv("llipaddr", tmp); /* store this for next time */ + + return 0; +} + +U_BOOT_CMD( + linklocal, 1, 1, do_link_local, + "acquire a network IP address using the link-local protocol", + "" +); + +#endif /* CONFIG_CMD_LINK_LOCAL */ diff --git a/doc/README.link-local b/doc/README.link-local new file mode 100644 index 0000000..e623e56 --- /dev/null +++ b/doc/README.link-local @@ -0,0 +1,76 @@ +------------------------------------------ + Link-local IP address auto-configuration +------------------------------------------ + +Negotiate with other link-local clients on the local network +for an address that doesn't require explicit configuration. +This is especially useful if a DHCP server cannot be guaranteed +to exist in all environments that the device must operate. + +This is an implementation of RFC3927. + +---------- + Commands +---------- + +When CONFIG_CMD_LINK_LOCAL is defined in the board config file, +the "linklocal" command is available. This running this will +take approximately 5 seconds while the address is negotiated. + +------------------------ + Environment interation +------------------------ + +The "llipaddr" variable is set with the most recently +negotiated address and is preferred in future negotiations. + +The "ipaddr", "netmask", and "gatewayip" variables are set +after successful negotiation to enable network access. + +------------- + Limitations +------------- + +RFC3927 requires that addresses are continuously checked to +avoid conflicts, however this can only happen when the NetLoop +is getting called. It is possible for a conflict to go undetected +until a command that accesses the network is executed. + +Using NetConsole is one way to ensure that NetLoop is always +processing packets and monitoring for conflicts. + +This is also not a concern if the feature is use to connect +directly to another machine that may not be running a DHCP server. + +---------------- + Example script +---------------- + +This script allows use of DHCP and/or Link-local controlled +by env variables. It depends on CONFIG_CMD_LINK_LOCAL, CONFIG_CMD_DHCP, +and CONFIG_BOOTP_MAY_FAIL. +If both fail or are disabled, static settings are used. + +#define CONFIG_EXTRA_ENV_SETTINGS \ + "ipconfigcmd=if test \"$dhcpenabled\" -ne 0;" \ + "then " \ + "dhcpfail=0;dhcp || dhcpfail=1;" \ + "else " \ + "dhcpfail=-1;" \ + "fi;" \ + "if test \"$linklocalenabled\" -ne 0 -a " \ + "\"$dhcpfail\" -ne 0;" \ + "then " \ + "linklocal;" \ + "llfail=0;" \ + "else " \ + "llfail=-1;" \ + "fi;" \ + "if test \"$llfail\" -ne 0 -a " \ + "\"$dhcpfail\" -ne 0; " \ + "then " \ + "setenv ipaddr $sipaddr; " \ + "setenv netmask $snetmask; " \ + "setenv gatewayip $sgatewayip; " \ + "fi;\0" \ + diff --git a/include/net.h b/include/net.h index 52b9a29..a902a64 100644 --- a/include/net.h +++ b/include/net.h @@ -395,7 +395,7 @@ extern int NetRestartWrap; /* Tried all network devices */
enum proto_t { BOOTP, RARP, ARP, TFTPGET, DHCP, PING, DNS, NFS, CDP, NETCONS, SNTP, - TFTPSRV, TFTPPUT + TFTPSRV, TFTPPUT, LINKLOCAL };
/* from net/net.c */ diff --git a/net/Makefile b/net/Makefile index f1c4859..5264687 100644 --- a/net/Makefile +++ b/net/Makefile @@ -32,15 +32,17 @@ COBJS-$(CONFIG_CMD_NET) += bootp.o COBJS-$(CONFIG_CMD_CDP) += cdp.o COBJS-$(CONFIG_CMD_DNS) += dns.o COBJS-$(CONFIG_CMD_NET) += eth.o +COBJS-$(CONFIG_CMD_LINK_LOCAL) += link_local.o COBJS-$(CONFIG_CMD_NET) += net.o COBJS-$(CONFIG_BOOTP_RANDOM_DELAY) += net_rand.o +COBJS-$(CONFIG_CMD_LINK_LOCAL) += net_rand.o COBJS-$(CONFIG_CMD_NFS) += nfs.o COBJS-$(CONFIG_CMD_PING) += ping.o COBJS-$(CONFIG_CMD_RARP) += rarp.o COBJS-$(CONFIG_CMD_SNTP) += sntp.o COBJS-$(CONFIG_CMD_NET) += tftp.o
-COBJS := $(COBJS-y) +COBJS := $(sort $(COBJS-y)) SRCS := $(COBJS:.o=.c) OBJS := $(addprefix $(obj),$(COBJS))
diff --git a/net/link_local.c b/net/link_local.c new file mode 100644 index 0000000..dde96ae --- /dev/null +++ b/net/link_local.c @@ -0,0 +1,332 @@ +/* + * RFC3927 ZeroConf IPv4 Link-Local addressing + * (see http://www.zeroconf.org/) + * + * Copied from BusyBox - networking/zcip.c + * + * Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com) + * Copyright (C) 2004 by David Brownell + * Copyright (C) 2010 by Joe Hershberger + * + * Licensed under the GPL v2 or later + */ + +#include <common.h> +#include <net.h> +#include "arp.h" +#include "net_rand.h" + +/* We don't need more than 32 bits of the counter */ +#define MONOTONIC_MS() ((unsigned)get_timer(0) * (1000 / CONFIG_SYS_HZ)) + +enum { +/* 169.254.0.0 */ + LINKLOCAL_ADDR = 0xa9fe0000, + + IN_CLASSB_NET = 0xffff0000, + IN_CLASSB_HOST = 0x0000ffff, + +/* protocol timeout parameters, specified in seconds */ + PROBE_WAIT = 1, + PROBE_MIN = 1, + PROBE_MAX = 2, + PROBE_NUM = 3, + MAX_CONFLICTS = 10, + RATE_LIMIT_INTERVAL = 60, + ANNOUNCE_WAIT = 2, + ANNOUNCE_NUM = 2, + ANNOUNCE_INTERVAL = 2, + DEFEND_INTERVAL = 10 +}; + +/* States during the configuration process. */ +static enum ll_state_t { + PROBE = 0, + RATE_LIMIT_PROBE, + ANNOUNCE, + MONITOR, + DEFEND, + DISABLED +} state = DISABLED; + +static IPaddr_t ip; +static int timeout_ms = -1; +static unsigned deadline_ms; +static unsigned conflicts; +static unsigned nprobes; +static unsigned nclaims; +static int ready; + +static void link_local_timeout(void); + +/** + * Pick a random link local IP address on 169.254/16, except that + * the first and last 256 addresses are reserved. + */ +static IPaddr_t pick(void) +{ + unsigned tmp; + + do { + tmp = rand() & IN_CLASSB_HOST; + } while (tmp > (IN_CLASSB_HOST - 0x0200)); + return (IPaddr_t) htonl((LINKLOCAL_ADDR + 0x0100) + tmp); +} + +/** + * Return milliseconds of random delay, up to "secs" seconds. + */ +static inline unsigned random_delay_ms(unsigned secs) +{ + return rand() % (secs * 1000); +} + +static void configure_wait(void) +{ + if (timeout_ms == -1) + return; + + /* poll, being ready to adjust current timeout */ + if (!timeout_ms) + timeout_ms = random_delay_ms(PROBE_WAIT); + + /* set deadline_ms to the point in time when we timeout */ + deadline_ms = MONOTONIC_MS() + timeout_ms; + + debug("...wait %d %s nprobes=%u, nclaims=%u\n", + timeout_ms, eth_get_name(), nprobes, nclaims); + + NetSetTimeout(timeout_ms, link_local_timeout); +} + +void link_local_start(void) +{ + ip = getenv_IPaddr("llipaddr"); + if (ip != 0 && (ip & IN_CLASSB_NET) != LINKLOCAL_ADDR) { + puts("invalid link address"); + net_set_state(NETLOOP_FAIL); + return; + } + NetOurSubnetMask = IN_CLASSB_NET; + + srand_mac(); + if (ip == 0) + ip = pick(); + + state = PROBE; + timeout_ms = 0; + conflicts = 0; + nprobes = 0; + nclaims = 0; + ready = 0; + + configure_wait(); +} + +static void link_local_timeout(void) +{ + switch (state) { + case PROBE: + /* timeouts in the PROBE state mean no conflicting ARP packets + have been received, so we can progress through the states */ + if (nprobes < PROBE_NUM) { + nprobes++; + debug("probe/%u %s@%pI4\n", + nprobes, eth_get_name(), &ip); + arp_raw_request(0, NetEtherNullAddr, ip); + timeout_ms = PROBE_MIN * 1000; + timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN); + } else { + /* Switch to announce state */ + state = ANNOUNCE; + nclaims = 0; + debug("announce/%u %s@%pI4\n", + nclaims, eth_get_name(), &ip); + arp_raw_request(ip, NetOurEther, ip); + timeout_ms = ANNOUNCE_INTERVAL * 1000; + } + break; + case RATE_LIMIT_PROBE: + /* timeouts in the RATE_LIMIT_PROBE state mean no conflicting + ARP packets have been received, so we can move immediately + to the announce state */ + state = ANNOUNCE; + nclaims = 0; + debug("announce/%u %s@%pI4\n", + nclaims, eth_get_name(), &ip); + arp_raw_request(ip, NetOurEther, ip); + timeout_ms = ANNOUNCE_INTERVAL * 1000; + break; + case ANNOUNCE: + /* timeouts in the ANNOUNCE state mean no conflicting ARP + packets have been received, so we can progress through + the states */ + if (nclaims < ANNOUNCE_NUM) { + nclaims++; + debug("announce/%u %s@%pI4\n", + nclaims, eth_get_name(), &ip); + arp_raw_request(ip, NetOurEther, ip); + timeout_ms = ANNOUNCE_INTERVAL * 1000; + } else { + /* Switch to monitor state */ + state = MONITOR; + printf("Successfully assigned %pI4\n", &ip); + NetCopyIP(&NetOurIP, &ip); + ready = 1; + conflicts = 0; + timeout_ms = -1; + /* Never timeout in the monitor state */ + NetSetTimeout(0, NULL); + + /* NOTE: all other exit paths should deconfig ... */ + net_set_state(NETLOOP_SUCCESS); + return; + } + break; + case DEFEND: + /* We won! No ARP replies, so just go back to monitor */ + state = MONITOR; + timeout_ms = -1; + conflicts = 0; + break; + default: + /* Invalid, should never happen. Restart the whole protocol */ + state = PROBE; + ip = pick(); + timeout_ms = 0; + nprobes = 0; + nclaims = 0; + break; + } + configure_wait(); +} + +void link_local_receive_arp(struct arp_hdr *arp, int len) +{ + int source_ip_conflict; + int target_ip_conflict; + + if (state == DISABLED) + return; + + /* We need to adjust the timeout in case we didn't receive a + conflicting packet. */ + if (timeout_ms > 0) { + unsigned diff = deadline_ms - MONOTONIC_MS(); + if ((int)(diff) < 0) { + /* Current time is greater than the expected timeout + time. This should never happen */ + debug("missed an expected timeout\n"); + timeout_ms = 0; + } else { + debug("adjusting timeout\n"); + timeout_ms = diff | 1; /* never 0 */ + } + } +/* + * XXX Don't bother with ethernet link just yet + if ((fds[0].revents & POLLIN) == 0) { + if (fds[0].revents & POLLERR) { + // FIXME: links routinely go down; + // this shouldn't necessarily exit. + bb_error_msg("iface %s is down", eth_get_name()); + if (ready) { + run(argv, "deconfig", &ip); + } + return EXIT_FAILURE; + } + continue; + } +*/ + + debug("%s recv arp type=%d, op=%d,\n", + eth_get_name(), ntohs(arp->ar_pro), + ntohs(arp->ar_op)); + debug("\tsource=%pM %pI4\n", + &arp->ar_sha, + &arp->ar_spa); + debug("\ttarget=%pM %pI4\n", + &arp->ar_tha, + &arp->ar_tpa); + + if (arp->ar_op != htons(ARPOP_REQUEST) + && arp->ar_op != htons(ARPOP_REPLY) + ) { + configure_wait(); + return; + } + + source_ip_conflict = 0; + target_ip_conflict = 0; + + if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0 + && memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0 + ) { + source_ip_conflict = 1; + } + if (arp->ar_op == htons(ARPOP_REQUEST) + && memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0 + && memcmp(&arp->ar_tha, NetOurEther, ARP_HLEN) != 0 + ) { + target_ip_conflict = 1; + } + + debug("state = %d, source ip conflict = %d, target ip conflict = %d\n", + state, source_ip_conflict, target_ip_conflict); + switch (state) { + case PROBE: + case ANNOUNCE: + /* When probing or announcing, check for source IP conflicts + and other hosts doing ARP probes (target IP conflicts). */ + if (source_ip_conflict || target_ip_conflict) { + conflicts++; + state = PROBE; + if (conflicts >= MAX_CONFLICTS) { + debug("%s ratelimit\n", eth_get_name()); + timeout_ms = RATE_LIMIT_INTERVAL * 1000; + state = RATE_LIMIT_PROBE; + } + + /* restart the whole protocol */ + ip = pick(); + timeout_ms = 0; + nprobes = 0; + nclaims = 0; + } + break; + case MONITOR: + /* If a conflict, we try to defend with a single ARP probe */ + if (source_ip_conflict) { + debug("monitor conflict -- defending\n"); + state = DEFEND; + timeout_ms = DEFEND_INTERVAL * 1000; + arp_raw_request(ip, NetOurEther, ip); + } + break; + case DEFEND: + /* Well, we tried. Start over (on conflict) */ + if (source_ip_conflict) { + state = PROBE; + debug("defend conflict -- starting over\n"); + ready = 0; + NetOurIP = 0; + + /* restart the whole protocol */ + ip = pick(); + timeout_ms = 0; + nprobes = 0; + nclaims = 0; + } + break; + default: + /* Invalid, should never happen. Restart the whole protocol */ + debug("invalid state -- starting over\n"); + state = PROBE; + ip = pick(); + timeout_ms = 0; + nprobes = 0; + nclaims = 0; + break; + } + configure_wait(); +} diff --git a/net/link_local.h b/net/link_local.h new file mode 100644 index 0000000..bb99816 --- /dev/null +++ b/net/link_local.h @@ -0,0 +1,24 @@ +/* + * RFC3927 ZeroConf IPv4 Link-Local addressing + * (see http://www.zeroconf.org/) + * + * Copied from BusyBox - networking/zcip.c + * + * Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com) + * Copyright (C) 2004 by David Brownell + * + * Licensed under the GPL v2 or later + */ + +#if defined(CONFIG_CMD_LINK_LOCAL) + +#ifndef __LINK_LOCAL_H__ +#define __LINK_LOCAL_H__ + +#include <common.h> + +void link_local_receive_arp(struct arp_hdr *arp, int len); +void link_local_start(void); + +#endif /* __LINK_LOCAL_H__ */ +#endif diff --git a/net/net.c b/net/net.c index b381974..c540c43 100644 --- a/net/net.c +++ b/net/net.c @@ -23,6 +23,12 @@ * - name of bootfile * Next step: ARP * + * LINK_LOCAL: + * + * Prerequisites: - own ethernet address + * We want: - own IP address + * Next step: ARP + * * RARP: * * Prerequisites: - own ethernet address @@ -89,6 +95,7 @@ #if defined(CONFIG_CMD_DNS) #include "dns.h" #endif +#include "link_local.h" #include "nfs.h" #include "ping.h" #include "rarp.h" @@ -402,6 +409,11 @@ restart: DnsStart(); break; #endif +#if defined(CONFIG_CMD_LINK_LOCAL) + case LINKLOCAL: + link_local_start(); + break; +#endif default: break; } @@ -1194,6 +1206,7 @@ common: case BOOTP: case CDP: case DHCP: + case LINKLOCAL: if (memcmp(NetOurEther, "\0\0\0\0\0\0", 6) == 0) { int num = eth_get_dev_index();