net: Add link-local addressing support

Code based on networking/zcip.c in busybox commit 8531d76a15890c2c535908ce888b2e2aed35b172 Signed-off-by: Joe Hershberger <[email protected]>
RobCrowston · May 23, 2012 · d22c338 · d22c338
1 parent 2280418
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Showing 8 changed files with 490 additions and 2 deletions.
diff --git 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
@@ -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
@@ -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
@@ -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
@@ -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))