lkl: lkl_add_arp_entry

Provides API support to add permanent arp entries to lkl so outsiders don't need to reply arp request. Signed-off-by: Yuan Liu <liuyuan@google.com>
lkl · Jun 18, 2016 · e2a4010 · e2a4010
1 parent e9c3b4a
commit e2a4010
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Showing 5 changed files with 98 additions and 2 deletions.
diff --git a/Documentation/lkl.txt b/Documentation/lkl.txt
@@ -189,9 +189,16 @@ are the list of those variable for your environment.
 ```
      $ LKL_HIJACK_NET_MTU=1280 lkl-hijack.sh ip address show
 ```
+* LKL_HIJACK_NET_ARP
+
+  Add a list of arp permanent entries in the form of "ip|mac;ip|mac;..."
+```
+     $ LKL_HIJACK_NET_ARP="192.168.13.100|12:34:56:78:9a:bc;192.168.13.101|12:34:56:78:9a:be"
+     lkl-hijack.sh ip neighbor show
+```
 * LKL_HIJACK_DEBUG
 
-  increate the verbose level of debug information.
+  increase the verbose level of debug information.
 ```
      $ LKL_HIJACK_DEBUG=1 lkl-hijack.sh ip address show
 ```

diff --git a/tools/lkl/include/lkl.h b/tools/lkl/include/lkl.h
@@ -301,6 +301,14 @@ struct lkl_netdev *lkl_netdev_dpdk_create(const char *ifname);
  */
 struct lkl_netdev *lkl_netdev_vde_create(const char *switch_path);
 
+/**
+ * lkl_add_arp_entry - add a permanent arp entry
+ * @ifindex - the ifindex of the interface
+ * @ip - ip address of the entry in network byte order
+ * @mac - mac address of the entry
+ */
+int lkl_add_arp_entry(int ifindex, unsigned int ip, void* mac);
+
 #ifdef __cplusplus
 }
 #endif

diff --git a/tools/lkl/lib/hijack/init.c b/tools/lkl/lib/hijack/init.c
@@ -62,6 +62,35 @@ int parse_mac_str(char *mac_str, __lkl__u8 mac[LKL_ETH_ALEN])
 	return 1;
 }
 
+/* Add permanent arp entries in the form of "ip|mac;ip|mac;..." */
+static void add_arp(int ifindex, char* entries) {
+	char *saveptr = NULL, *token = NULL;
+	char *ip = NULL, *mac_str = NULL;
+	int ret = 0;
+	__lkl__u8 mac[LKL_ETH_ALEN];
+	unsigned int ip_addr;
+
+	for (token = strtok_r(entries, ";", &saveptr); token;
+	     token = strtok_r(NULL, ";", &saveptr)) {
+		ip = strtok(token, "|");
+		mac_str = strtok(NULL, "|");
+		if (ip == NULL || mac_str == NULL || strtok(NULL, "|") != NULL) {
+			return;
+		}
+		ip_addr = inet_addr(ip);
+		ret = parse_mac_str(mac_str, mac);
+		if (ret != 1) {
+			fprintf(stderr, "Failed to parse mac: %s\n", mac_str);
+			return;
+		}
+		ret = lkl_add_arp_entry(ifindex, ip_addr, mac);
+		if (ret) {
+			fprintf(stderr, "Failed to add arp entry: %s\n", lkl_strerror(ret));
+			return;
+		}
+	}
+	return;
+}
 
 /* We don't have an easy way to make FILE*s out of our fds, so we
  * can't use e.g. fgets */
@@ -165,6 +194,7 @@ hijack_init(void)
 	char *debug = getenv("LKL_HIJACK_DEBUG");
 	char *mount = getenv("LKL_HIJACK_MOUNT");
 	struct lkl_netdev *nd = NULL;
+	char *arp_entries = getenv("LKL_HIJACK_NET_ARP");
 
 	/* Must be run before lkl_netdev_tap_create */
 	fixup_netdev_tap_ops();
@@ -272,6 +302,9 @@ hijack_init(void)
 
 	if (mount)
 		mount_cmds_exec(mount, mount_fs);
+
+	if (nd_ifindex >=0 && arp_entries)
+		add_arp(nd_ifindex, arp_entries);
 }
 
 void __attribute__((destructor))

diff --git a/tools/lkl/lib/net.c b/tools/lkl/lib/net.c
@@ -3,7 +3,6 @@
 #include "endian.h"
 #include <lkl_host.h>
 
-
 static inline void set_sockaddr(struct lkl_sockaddr_in *sin, unsigned int addr,
 				unsigned short port)
 {
@@ -159,3 +158,45 @@ int lkl_netdev_get_ifindex(int id)
 
 	return ret < 0 ? ret : ifr.lkl_ifr_ifindex;
 }
+
+struct lkl_arpreq {
+	struct lkl_sockaddr arp_pa;      /* protocol address */
+	struct lkl_sockaddr arp_ha;      /* hardware address */
+	int             arp_flags;   /* flags */
+	struct lkl_sockaddr arp_netmask; /* netmask of protocol address */
+	char            arp_dev[LKL_IFNAMSIZ];
+};
+
+#define LKL_ATF_PERM 0x04
+#define LKL_ATF_COM 0x02
+
+int lkl_add_arp_entry(int ifindex, unsigned int ip, void* mac) {
+	struct lkl_arpreq req;
+	int ret = 0;
+	struct lkl_ifreq ifr;
+	struct lkl_sockaddr_in* sin = (struct lkl_sockaddr_in*)&req.arp_pa;
+	int sock;
+
+	bzero(&req, sizeof(req));
+	sin->sin_family = LKL_AF_INET;
+	sin->sin_addr.lkl_s_addr = ip;
+	memcpy(req.arp_ha.sa_data, mac, LKL_ETH_ALEN);
+
+	sock = lkl_sys_socket(LKL_AF_INET, LKL_SOCK_DGRAM, 0);
+	if (sock < 0) {
+		return sock;
+	}
+
+	req.arp_flags = LKL_ATF_PERM | LKL_ATF_COM;
+
+	ret = ifindex_to_name(sock, &ifr, ifindex);
+	if (ret < 0) {
+		lkl_sys_close(sock);
+		return ret;
+	}
+	strcpy(req.arp_dev, ifr.ifr_ifrn.ifrn_name);
+
+	ret = lkl_sys_ioctl(sock, LKL_SIOCSARP, (long)(&req));
+	lkl_sys_close(sock);
+	return ret;
+}
diff --git a/tools/lkl/tests/hijack-test.sh b/tools/lkl/tests/hijack-test.sh
@@ -94,6 +94,13 @@ sudo arp -d 192.168.13.2
 sudo ping -i 0.01 -c 65 192.168.13.2 &
 ${hijack_script} sleep 3
 
+# add arp entries
+ans=$(LKL_HIJACK_NET_ARP="192.168.13.100|12:34:56:78:9a:bc;192.168.13.101|12:34:56:78:9a:be"\
+  ${hijack_script} ip neighbor show) || true
+echo "$ans" | tail -n 15 | grep "12:34:56:78:9a:bc"
+echo "$ans" | tail -n 15 | grep "12:34:56:78:9a:be"
+
+
 sh ${script_dir}/run_netperf.sh 192.168.13.1 1 0 TCP_STREAM
 sh ${script_dir}/run_netperf.sh 192.168.13.1 1 0 TCP_RR