nhrpd: implement next hop resolution protocol
This provides DMVPN support and integrates to strongSwan. Please read
README.nhrpd and README.kernel for more details.
diff --git a/nhrpd/os.h b/nhrpd/os.h
new file mode 100644
index 0000000..0fbe8b0
--- /dev/null
+++ b/nhrpd/os.h
@@ -0,0 +1,5 @@
+
+int os_socket(void);
+int os_sendmsg(const uint8_t *buf, size_t len, int ifindex, const uint8_t *addr, size_t addrlen);
+int os_recvmsg(uint8_t *buf, size_t *len, int *ifindex, uint8_t *addr, size_t *addrlen);
+int os_configure_dmvpn(unsigned int ifindex, const char *ifname, int af);