4 files changed, 103 insertions, 1 deletions
diff --git a/sysdep/bsd/sysio.h b/sysdep/bsd/sysio.h
index 847ce26..95f7dcf 100644
--- a/sysdep/bsd/sysio.h
+++ b/sysdep/bsd/sysio.h
@@ -237,3 +237,34 @@ sk_set_md5_auth_int(sock *s, sockaddr *sa, char *passwd)
 
   return rv;
 }
+
+
+#ifndef IPV6
+
+static int
+sk_set_min_ttl4(sock *s, int ttl)
+{
+  if (setsockopt(s->fd, IPPROTO_IP, IP_MINTTL, &ttl, sizeof(ttl)) < 0)
+  {
+    if (errno == ENOPROTOOPT)
+      log(L_ERR "Kernel does not support IPv4 TTL security");
+    else
+      log(L_ERR "sk_set_min_ttl4: setsockopt: %m");
+
+    return -1;
+  }
+
+  return 0;
+}
+
+#else
+
+static int
+sk_set_min_ttl6(sock *s, int ttl)
+{
+  log(L_ERR "IPv6 TTL security not supported");
+  return -1;
+}
+
+#endif
+
diff --git a/sysdep/linux/sysio.h b/sysdep/linux/sysio.h
index 9c10333..bb52280 100644
--- a/sysdep/linux/sysio.h
+++ b/sysdep/linux/sysio.h
@@ -309,3 +309,51 @@ sysio_prepare_tx_cmsgs(sock *s, struct msghdr *msg, void *cbuf, size_t cbuflen)
 */
 
 #endif
+
+
+#ifndef IP_MINTTL
+#define IP_MINTTL 21
+#endif
+
+#ifndef IPV6_MINHOPCOUNT
+#define IPV6_MINHOPCOUNT 73
+#endif
+
+
+#ifndef IPV6
+
+static int
+sk_set_min_ttl4(sock *s, int ttl)
+{
+  if (setsockopt(s->fd, IPPROTO_IP, IP_MINTTL, &ttl, sizeof(ttl)) < 0)
+  {
+    if (errno == ENOPROTOOPT)
+      log(L_ERR "Kernel does not support IPv4 TTL security");
+    else
+      log(L_ERR "sk_set_min_ttl4: setsockopt: %m");
+
+    return -1;
+  }
+
+  return 0;
+}
+
+#else
+
+static int
+sk_set_min_ttl6(sock *s, int ttl)
+{
+  if (setsockopt(s->fd, IPPROTO_IPV6, IPV6_MINHOPCOUNT, &ttl, sizeof(ttl)) < 0)
+  {
+    if (errno == ENOPROTOOPT)
+      log(L_ERR "Kernel does not support IPv6 TTL security");
+    else
+      log(L_ERR "sk_set_min_ttl4: setsockopt: %m");
+
+    return -1;
+  }
+
+  return 0;
+}
+
+#endif
diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index b6c1b86..815989f 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -805,7 +805,7 @@ bad:
 }
 
 /**
- * sk_set_ttl - set TTL for given socket.
+ * sk_set_ttl - set transmit TTL for given socket.
  * @s: socket
  * @ttl: TTL value
  *
@@ -828,6 +828,28 @@ sk_set_ttl(sock *s, int ttl)
   return (err ? -1 : 0);
 }
 
+/**
+ * sk_set_min_ttl - set minimal accepted TTL for given socket.
+ * @s: socket
+ * @ttl: TTL value
+ *
+ * Can be used in TTL security implementation
+ *
+ * Result: 0 for success, -1 for an error.
+ */
+
+int
+sk_set_min_ttl(sock *s, int ttl)
+{
+  int err;
+#ifdef IPV6
+  err = sk_set_min_ttl6(s, ttl);
+#else
+  err = sk_set_min_ttl4(s, ttl);
+#endif
+
+  return err;
+}
 
 /**
  * sk_set_md5_auth - add / remove MD5 security association for given socket.
diff --git a/sysdep/unix/main.c b/sysdep/unix/main.c
index 610d207..5547791 100644
--- a/sysdep/unix/main.c
+++ b/sysdep/unix/main.c
@@ -17,6 +17,7 @@
 #include <signal.h>
 #include <pwd.h>
 #include <grp.h>
+#include <sys/stat.h>
 
 #include "nest/bird.h"
 #include "lib/lists.h"