X-Git-Url: http://www.project-moonshot.org/gitweb/?p=mech_eap.git;a=blobdiff_plain;f=libeap%2Fsrc%2Fap%2Fdhcp_snoop.c;fp=libeap%2Fsrc%2Fap%2Fdhcp_snoop.c;h=f0212fb2a984bfa39d7b2fd3274b5e6003d4aee2;hp=0000000000000000000000000000000000000000;hb=f3746d009c6d7f50025af1f58a85e5fee9680be6;hpb=244f18d04aaf29e68495b5ffeb40ef5cca50942f

diff --git a/libeap/src/ap/dhcp_snoop.c b/libeap/src/ap/dhcp_snoop.c
new file mode 100644
index 0000000..f0212fb
--- /dev/null
+++ b/libeap/src/ap/dhcp_snoop.c
@@ -0,0 +1,179 @@
+/*
+ * DHCP snooping for Proxy ARP
+ * Copyright (c) 2014, Qualcomm Atheros, Inc.
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "utils/includes.h"
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+
+#include "utils/common.h"
+#include "l2_packet/l2_packet.h"
+#include "hostapd.h"
+#include "sta_info.h"
+#include "ap_drv_ops.h"
+#include "x_snoop.h"
+#include "dhcp_snoop.h"
+
+struct bootp_pkt {
+	struct iphdr iph;
+	struct udphdr udph;
+	u8 op;
+	u8 htype;
+	u8 hlen;
+	u8 hops;
+	be32 xid;
+	be16 secs;
+	be16 flags;
+	be32 client_ip;
+	be32 your_ip;
+	be32 server_ip;
+	be32 relay_ip;
+	u8 hw_addr[16];
+	u8 serv_name[64];
+	u8 boot_file[128];
+	u8 exten[312];
+} STRUCT_PACKED;
+
+#define DHCPACK	5
+static const u8 ic_bootp_cookie[] = { 99, 130, 83, 99 };
+
+
+static const char * ipaddr_str(u32 addr)
+{
+	static char buf[17];
+
+	os_snprintf(buf, sizeof(buf), "%u.%u.%u.%u",
+		    (addr >> 24) & 0xff, (addr >> 16) & 0xff,
+		    (addr >> 8) & 0xff, addr & 0xff);
+	return buf;
+}
+
+
+static void handle_dhcp(void *ctx, const u8 *src_addr, const u8 *buf,
+			size_t len)
+{
+	struct hostapd_data *hapd = ctx;
+	const struct bootp_pkt *b;
+	struct sta_info *sta;
+	int exten_len;
+	const u8 *end, *pos;
+	int res, msgtype = 0, prefixlen = 32;
+	u32 subnet_mask = 0;
+	u16 tot_len;
+
+	exten_len = len - ETH_HLEN - (sizeof(*b) - sizeof(b->exten));
+	if (exten_len < 4)
+		return;
+
+	b = (const struct bootp_pkt *) &buf[ETH_HLEN];
+	tot_len = ntohs(b->iph.tot_len);
+	if (tot_len > (unsigned int) (len - ETH_HLEN))
+		return;
+
+	if (os_memcmp(b->exten, ic_bootp_cookie, ARRAY_SIZE(ic_bootp_cookie)))
+		return;
+
+	/* Parse DHCP options */
+	end = (const u8 *) b + tot_len;
+	pos = &b->exten[4];
+	while (pos < end && *pos != 0xff) {
+		const u8 *opt = pos++;
+
+		if (*opt == 0) /* padding */
+			continue;
+
+		pos += *pos + 1;
+		if (pos >= end)
+			break;
+
+		switch (*opt) {
+		case 1:  /* subnet mask */
+			if (opt[1] == 4)
+				subnet_mask = WPA_GET_BE32(&opt[2]);
+			if (subnet_mask == 0)
+				return;
+			while (!(subnet_mask & 0x1)) {
+				subnet_mask >>= 1;
+				prefixlen--;
+			}
+			break;
+		case 53: /* message type */
+			if (opt[1])
+				msgtype = opt[2];
+			break;
+		default:
+			break;
+		}
+	}
+
+	if (msgtype == DHCPACK) {
+		if (b->your_ip == 0)
+			return;
+
+		/* DHCPACK for DHCPREQUEST */
+		sta = ap_get_sta(hapd, b->hw_addr);
+		if (!sta)
+			return;
+
+		wpa_printf(MSG_DEBUG, "dhcp_snoop: Found DHCPACK for " MACSTR
+			   " @ IPv4 address %s/%d",
+			   MAC2STR(sta->addr),
+			   ipaddr_str(be_to_host32(b->your_ip)),
+			   prefixlen);
+
+		if (sta->ipaddr == b->your_ip)
+			return;
+
+		if (sta->ipaddr != 0) {
+			wpa_printf(MSG_DEBUG,
+				   "dhcp_snoop: Removing IPv4 address %s from the ip neigh table",
+				   ipaddr_str(be_to_host32(sta->ipaddr)));
+			hostapd_drv_br_delete_ip_neigh(hapd, 4,
+						       (u8 *) &sta->ipaddr);
+		}
+
+		res = hostapd_drv_br_add_ip_neigh(hapd, 4, (u8 *) &b->your_ip,
+						  prefixlen, sta->addr);
+		if (res) {
+			wpa_printf(MSG_DEBUG,
+				   "dhcp_snoop: Adding ip neigh table failed: %d",
+				   res);
+			return;
+		}
+		sta->ipaddr = b->your_ip;
+	}
+
+	if (hapd->conf->disable_dgaf && is_broadcast_ether_addr(buf)) {
+		for (sta = hapd->sta_list; sta; sta = sta->next) {
+			if (!(sta->flags & WLAN_STA_AUTHORIZED))
+				continue;
+			x_snoop_mcast_to_ucast_convert_send(hapd, sta,
+							    (u8 *) buf, len);
+		}
+	}
+}
+
+
+int dhcp_snoop_init(struct hostapd_data *hapd)
+{
+	hapd->sock_dhcp = x_snoop_get_l2_packet(hapd, handle_dhcp,
+						L2_PACKET_FILTER_DHCP);
+	if (hapd->sock_dhcp == NULL) {
+		wpa_printf(MSG_DEBUG,
+			   "dhcp_snoop: Failed to initialize L2 packet processing for DHCP packet: %s",
+			   strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+
+void dhcp_snoop_deinit(struct hostapd_data *hapd)
+{
+	l2_packet_deinit(hapd->sock_dhcp);
+}