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/znl.c b/nhrpd/znl.c
new file mode 100644
index 0000000..2216d97
--- /dev/null
+++ b/nhrpd/znl.c
@@ -0,0 +1,160 @@
+/* Netlink helpers for zbuf
+ * Copyright (c) 2014-2015 Timo Teräs
+ *
+ * This file is free software: you may copy, redistribute and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+#include "znl.h"
+
+#define ZNL_ALIGN(len) (((len)+3) & ~3)
+
+void *znl_push(struct zbuf *zb, size_t n)
+{
+ return zbuf_pushn(zb, ZNL_ALIGN(n));
+}
+
+void *znl_pull(struct zbuf *zb, size_t n)
+{
+ return zbuf_pulln(zb, ZNL_ALIGN(n));
+}
+
+struct nlmsghdr *znl_nlmsg_push(struct zbuf *zb, uint16_t type, uint16_t flags)
+{
+ struct nlmsghdr *n;
+
+ n = znl_push(zb, sizeof(*n));
+ if (!n) return NULL;
+
+ *n = (struct nlmsghdr) {
+ .nlmsg_type = type,
+ .nlmsg_flags = flags,
+ };
+ return n;
+}
+
+void znl_nlmsg_complete(struct zbuf *zb, struct nlmsghdr *n)
+{
+ n->nlmsg_len = zb->tail - (uint8_t*)n;
+}
+
+struct nlmsghdr *znl_nlmsg_pull(struct zbuf *zb, struct zbuf *payload)
+{
+ struct nlmsghdr *n;
+ size_t plen;
+
+ n = znl_pull(zb, sizeof(*n));
+ if (!n) return NULL;
+
+ plen = n->nlmsg_len - sizeof(*n);
+ zbuf_init(payload, znl_pull(zb, plen), plen, plen);
+ zbuf_may_pulln(zb, ZNL_ALIGN(plen) - plen);
+
+ return n;
+}
+
+struct rtattr *znl_rta_push(struct zbuf *zb, uint16_t type, const void *val, size_t len)
+{
+ struct rtattr *rta;
+ uint8_t *dst;
+
+ rta = znl_push(zb, ZNL_ALIGN(sizeof(*rta)) + ZNL_ALIGN(len));
+ if (!rta) return NULL;
+
+ *rta = (struct rtattr) {
+ .rta_type = type,
+ .rta_len = ZNL_ALIGN(sizeof(*rta)) + len,
+ };
+
+ dst = (uint8_t *)(rta+1);
+ memcpy(dst, val, len);
+ memset(dst+len, 0, ZNL_ALIGN(len) - len);
+
+ return rta;
+}
+
+struct rtattr *znl_rta_push_u32(struct zbuf *zb, uint16_t type, uint32_t val)
+{
+ return znl_rta_push(zb, type, &val, sizeof(val));
+}
+
+struct rtattr *znl_rta_nested_push(struct zbuf *zb, uint16_t type)
+{
+ struct rtattr *rta;
+
+ rta = znl_push(zb, sizeof(*rta));
+ if (!rta) return NULL;
+
+ *rta = (struct rtattr) {
+ .rta_type = type,
+ };
+ return rta;
+}
+
+void znl_rta_nested_complete(struct zbuf *zb, struct rtattr *rta)
+{
+ size_t len = zb->tail - (uint8_t*) rta;
+ size_t align = ZNL_ALIGN(len) - len;
+
+ if (align) {
+ void *dst = zbuf_pushn(zb, align);
+ if (dst) memset(dst, 0, align);
+ }
+ rta->rta_len = len;
+}
+
+struct rtattr *znl_rta_pull(struct zbuf *zb, struct zbuf *payload)
+{
+ struct rtattr *rta;
+ size_t plen;
+
+ rta = znl_pull(zb, sizeof(*rta));
+ if (!rta) return NULL;
+
+ if (rta->rta_len > sizeof(*rta)) {
+ plen = rta->rta_len - sizeof(*rta);
+ zbuf_init(payload, znl_pull(zb, plen), plen, plen);
+ } else {
+ zbuf_init(payload, NULL, 0, 0);
+ }
+
+ return rta;
+}
+
+int znl_open(int protocol, int groups)
+{
+ struct sockaddr_nl addr;
+ int fd, buf = 128 * 1024;
+
+ fd = socket(AF_NETLINK, SOCK_RAW, protocol);
+ if (fd < 0)
+ return -1;
+
+ fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | O_NONBLOCK);
+ fcntl(fd, F_SETFD, FD_CLOEXEC);
+ if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &buf, sizeof(buf)) < 0)
+ goto error;
+
+ memset(&addr, 0, sizeof(addr));
+ addr.nl_family = AF_NETLINK;
+ addr.nl_groups = groups;
+ if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0)
+ goto error;
+
+ return fd;
+error:
+ close(fd);
+ return -1;
+}
+