Allow overriding the interface-identifier for public addresses

3 files changed, 24 insertions, 13 deletions

diff --git a/src/odhcp6c.c b/src/odhcp6c.c
index 4fefcd7..df89eb9 100644
--- a/src/odhcp6c.c
+++ b/src/odhcp6c.c
@@ -27,6 +27,7 @@
 #include <net/if.h>
 #include <sys/wait.h>
 #include <sys/syscall.h>
+#include <arpa/inet.h>
 
 #include "odhcp6c.h"
 #include "ra.h"
@@ -55,11 +56,12 @@ int main(_unused int argc, char* const argv[])
 	char *optpos;
 	uint16_t opttype;
 	enum odhcp6c_ia_mode ia_na_mode = IA_MODE_TRY;
+	static struct in6_addr ifid = IN6ADDR_ANY_INIT;
 
 	bool help = false, daemonize = false;
 	int logopt = LOG_PID;
 	int c, request_pd = 0;
-	while ((c = getopt(argc, argv, "S::N:P:c:r:s:khedp:")) != -1) {
+	while ((c = getopt(argc, argv, "S::N:P:c:i:r:s:khedp:")) != -1) {
 		switch (c) {
 		case 'S':
 			allow_slaac_only = (optarg) ? atoi(optarg) : -1;
@@ -98,6 +100,11 @@ int main(_unused int argc, char* const argv[])
 			}
 			break;
 
+		case 'i':
+			if (inet_pton(AF_INET6, optarg, &ifid) != 1)
+				help = true;
+			break;
+
 		case 'r':
 			optpos = optarg;
 			while (optpos[0]) {
@@ -151,7 +158,7 @@ int main(_unused int argc, char* const argv[])
 	signal(SIGUSR2, sighandler);
 
 	if ((urandom_fd = open("/dev/urandom", O_CLOEXEC | O_RDONLY)) < 0 ||
-			init_dhcpv6(ifname, request_pd) || ra_init(ifname) ||
+			init_dhcpv6(ifname, request_pd) || ra_init(ifname, &ifid) ||
 			script_init(script, ifname)) {
 		syslog(LOG_ERR, "failed to initialize: %s", strerror(errno));
 		return 3;
@@ -314,6 +321,7 @@ static int usage(void)
 	"	-N <mode>	Mode for requesting addresses [try|force|none]\n"
 	"	-P <length>	Request IPv6-Prefix (0 = auto)\n"
 	"	-c <clientid>	Override client-ID (base-16 encoded)\n"
+	"	-i <iface-id>	Use a custom interface identifier for RA handling\n"
 	"	-r <options>	Options to be requested (comma-separated)\n"
 	"	-s <script>	Status update script (/usr/sbin/odhcp6c-update)\n"
 	"	-k		Don't send a RELEASE when stopping\n"
diff --git a/src/ra.c b/src/ra.c
index b1526ae..4690d41 100644
--- a/src/ra.c
+++ b/src/ra.c
@@ -42,11 +42,12 @@ static struct in6_addr lladdr = IN6ADDR_ANY_INIT;
 
 static void ra_send_rs(int signal __attribute__((unused)));
 
-int ra_init(const char *ifname)
+int ra_init(const char *ifname, const struct in6_addr *ifid)
 {
 	sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
 	if_index = if_nametoindex(ifname);
 	strncpy(if_name, ifname, sizeof(if_name) - 1);
+	lladdr = *ifid;
 
 	// Filter ICMPv6 package types
 	struct icmp6_filter filt;
@@ -74,17 +75,19 @@ int ra_init(const char *ifname)
 	fcntl(sock, F_SETOWN, ourpid);
 	fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_ASYNC);
 
-	// Get LL-addr
-	FILE *fp = fopen("/proc/net/if_inet6", "r");
-	if (fp) {
-		char addrbuf[33], ifbuf[16];
-		while (fscanf(fp, "%32s %*x %*x %*x %*x %15s", addrbuf, ifbuf) == 2) {
-			if (!strcmp(ifbuf, if_name)) {
-				script_unhexlify((uint8_t*)&lladdr, sizeof(lladdr), addrbuf);
-				break;
+	if (IN6_IS_ADDR_UNSPECIFIED(&lladdr)) {
+		// Autodetect interface-id if not specified
+		FILE *fp = fopen("/proc/net/if_inet6", "r");
+		if (fp) {
+			char addrbuf[33], ifbuf[16];
+			while (fscanf(fp, "%32s %*x %*x %*x %*x %15s", addrbuf, ifbuf) == 2) {
+				if (!strcmp(ifbuf, if_name)) {
+					script_unhexlify((uint8_t*)&lladdr, sizeof(lladdr), addrbuf);
+					break;
+				}
 			}
+			fclose(fp);
 		}
-		fclose(fp);
 	}
 
 	// Open rtnetlink socket
diff --git a/src/ra.h b/src/ra.h
index f87c4f7..f66ff26 100644
--- a/src/ra.h
+++ b/src/ra.h
@@ -34,6 +34,6 @@ struct icmpv6_opt {
 	(void*)(opt + opt->len) <= (void*)(end); opt += opt->len)
 
 
-int ra_init(const char *ifname);
+int ra_init(const char *ifname, const struct in6_addr *ifid);
 bool ra_process(void);
 bool ra_rtnl_process(void);