From fc7fb637811089b4f26fb00ca81a0d05c09076bd Mon Sep 17 00:00:00 2001
From: Steven Barth <steven@midlink.org>
Date: Fri, 30 May 2014 16:59:53 +0200
Subject: [PATCH] Make filtering customizable

---
 src/config.c | 8 ++++++++
 src/dhcpv4.c | 7 +++----
 src/dhcpv6.c | 8 +++-----
 src/odhcpd.h | 2 ++
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/src/config.c b/src/config.c
index 6dd52bb..db5ca3b 100644
--- a/src/config.c
+++ b/src/config.c
@@ -32,6 +32,7 @@ enum {
 	IFACE_ATTR_NDP,
 	IFACE_ATTR_DNS,
 	IFACE_ATTR_DOMAIN,
+	IFACE_ATTR_FILTER_CLASS,
 	IFACE_ATTR_DHCPV6_RAW,
 	IFACE_ATTR_RA_DEFAULT,
 	IFACE_ATTR_RA_MANAGEMENT,
@@ -62,6 +63,7 @@ static const struct blobmsg_policy iface_attrs[IFACE_ATTR_MAX] = {
 	[IFACE_ATTR_NDP] = { .name = "ndp", .type = BLOBMSG_TYPE_STRING },
 	[IFACE_ATTR_DNS] = { .name = "dns", .type = BLOBMSG_TYPE_ARRAY },
 	[IFACE_ATTR_DOMAIN] = { .name = "domain", .type = BLOBMSG_TYPE_ARRAY },
+	[IFACE_ATTR_FILTER_CLASS] = { .name = "filter_class", .type = BLOBMSG_TYPE_STRING },
 	[IFACE_ATTR_DHCPV6_RAW] = { .name = "dhcpv6_raw", .type = BLOBMSG_TYPE_STRING },
 	[IFACE_ATTR_PD_MANAGER] = { .name = "pd_manager", .type = BLOBMSG_TYPE_STRING },
 	[IFACE_ATTR_PD_CER] = { .name = "pd_cer", .type = BLOBMSG_TYPE_STRING },
@@ -152,6 +154,7 @@ static void clean_interface(struct interface *iface)
 	free(iface->static_ndp);
 	free(iface->dhcpv4_dns);
 	free(iface->dhcpv6_raw);
+	free(iface->filter_class);
 	memset(&iface->ra, 0, sizeof(*iface) - offsetof(struct interface, ra));
 }
 
@@ -457,6 +460,11 @@ int config_parse_interface(void *data, size_t len, const char *name, bool overwr
 		}
 	}
 
+	if ((c = tb[IFACE_ATTR_FILTER_CLASS])) {
+		iface->filter_class = realloc(iface->filter_class, blobmsg_data_len(c) + 1);
+		memcpy(iface->filter_class, blobmsg_get_string(c), blobmsg_data_len(c) + 1);
+	}
+
 	if ((c = tb[IFACE_ATTR_DHCPV6_RAW])) {
 		iface->dhcpv6_raw_len = blobmsg_data_len(c) / 2;
 		iface->dhcpv6_raw = realloc(iface->dhcpv6_raw, iface->dhcpv6_raw_len);
diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index b8e0c95..628efcd 100644
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -37,7 +37,6 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
 		enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr,
 		const char *hostname);
-static const char *excluded_class = "HOMENET";
 
 // Create socket and register events
 int init_dhcpv4(void)
@@ -294,11 +293,11 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 		} else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
 			if (memcmp(opt->data, &ifaddr.sin_addr, 4))
 				return;
-		} else if (opt->type == DHCPV4_OPT_USER_CLASS) {
+		} else if (iface->filter_class && opt->type == DHCPV4_OPT_USER_CLASS) {
 			uint8_t *c = opt->data, *cend = &opt->data[opt->len];
 			for (; c < cend && &c[*c] < cend; c = &c[1 + *c]) {
-				size_t elen = strlen(excluded_class);
-				if (*c == elen && !memcmp(&c[1], excluded_class, elen))
+				size_t elen = strlen(iface->filter_class);
+				if (*c == elen && !memcmp(&c[1], iface->filter_class, elen))
 					return; // Ignore from homenet
 			}
 		}
diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index 37dc3f5..aaefa5e 100644
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -22,8 +22,6 @@
 #include "odhcpd.h"
 #include "dhcpv6.h"
 
-static const char *excluded_class = "HOMENET";
-
 
 static void relay_client_request(struct sockaddr_in6 *source,
 		const void *data, size_t len, struct interface *iface);
@@ -293,11 +291,11 @@ static void handle_client_request(void *addr, void *data, size_t len,
 			if (olen != ntohs(dest.serverid_length) ||
 					memcmp(odata, &dest.duid_type, olen))
 				return; // Not for us
-		} else if (otype == DHCPV6_OPT_USER_CLASS) {
+		} else if (iface->filter_class && otype == DHCPV6_OPT_USER_CLASS) {
 			uint8_t *c = odata, *cend = &odata[olen];
 			for (; &c[2] <= cend && &c[2 + (c[0] << 8) + c[1]] <= cend; c = &c[2 + (c[0] << 8) + c[1]]) {
-				size_t elen = strlen(excluded_class);
-				if (((((size_t)c[0]) << 8) | c[1]) == elen && !memcmp(&c[2], excluded_class, elen))
+				size_t elen = strlen(iface->filter_class);
+				if (((((size_t)c[0]) << 8) | c[1]) == elen && !memcmp(&c[2], iface->filter_class, elen))
 					return; // Ignore from homenet
 			}
 		} else if (otype == DHCPV6_OPT_IA_PD) {
diff --git a/src/odhcpd.h b/src/odhcpd.h
index 64ffca2..dfaec9b 100644
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -165,6 +165,8 @@ struct interface {
 
 	char *upstream;
 	size_t upstream_len;
+
+	char *filter_class;
 };
 
 extern struct list_head interfaces;
-- 
2.25.1