lib: Add secure random generator

This adds a secure random number generator. It will use OS specific
calls with a fallback to OpenSSL if available.

2 files changed, 81 insertions, 5 deletions

diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index 99dd96fc..e08869b8 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -16,7 +16,7 @@ protobuf_generate_c(FRCT_ENROLL_SRCS FRCT_ENROLL_HDRS frct_enroll.proto)
 if (NOT APPLE)
   find_library(LIBRT_LIBRARIES rt)
   if (NOT LIBRT_LIBRARIES)
-    message(FATAL_ERROR "librt not found")
+    message(FATAL_ERROR "Could not find librt.")
   endif ()
 else ()
   set(LIBRT_LIBRARIES "")
@@ -24,9 +24,14 @@ endif ()
 
 find_library(LIBPTHREAD_LIBRARIES pthread)
 if (NOT LIBPTHREAD_LIBRARIES)
-  message(FATAL_ERROR "libpthread not found")
+  message(FATAL_ERROR "Could not find libpthread.")
 endif ()
 
+find_path(LINUX_RND_HDR
+  sys/random.h
+  HINTS /usr/include /usr/local/include
+  )
+
 set(SOURCE_FILES
   # Add source files here
   bitmap.c
@@ -46,6 +51,7 @@ set(SOURCE_FILES
   nsm.c
   qos.c
   qoscube.c
+  random.c
   rib.c
   sha3.c
   shm_flow_set.c
@@ -60,14 +66,33 @@ add_library(ouroboros SHARED ${SOURCE_FILES} ${IRM_PROTO_SRCS}
   ${IPCP_PROTO_SRCS} ${DIF_CONFIG_PROTO_SRCS} ${CDAP_PROTO_SRCS}
   ${CACEP_PROTO_SRCS} ${RO_PROTO_SRCS} ${FRCT_ENROLL_SRCS})
 
-target_link_libraries(ouroboros ${LIBRT_LIBRARIES}
-  ${LIBPTHREAD_LIBRARIES} ${PROTOBUF_C_LIBRARY})
-
 include(AddCompileFlags)
 if (CMAKE_BUILD_TYPE MATCHES Debug)
   add_compile_flags(ouroboros -DCONFIG_OUROBOROS_DEBUG)
 endif (CMAKE_BUILD_TYPE MATCHES Debug)
 
+if (CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
+  message(STATUS "Found FreeBSD, using arc4random.")
+else()
+  if (${LINUX_RND_HDR} STREQUAL "LINUX_RND_HDR-NOTFOUND")
+    find_package(OpenSSL)
+    if (NOT OPENSSL_FOUND)
+      message(STATUS "No secure random generation, please install OpenSSL.")
+    else()
+      message(STATUS "OpenSSL found")
+      include_directories($OPENSSL_INCLUDE_DIR})
+      add_compile_flags(ouroboros -DHAVE_OPENSSL)
+    endif()
+  else ()
+    message(STATUS "Found linux random header in ${LINUX_RND_HDR}.")
+    include_directories(${LINUX_RND_HDR})
+    add_compile_flags(ouroboros -DHAVE_SYS_RANDOM)
+  endif ()
+endif()
+
+target_link_libraries(ouroboros ${LIBRT_LIBRARIES}
+  ${LIBPTHREAD_LIBRARIES} ${PROTOBUF_C_LIBRARY} ${OPENSSL_LIBRARIES})
+
 install(TARGETS ouroboros LIBRARY DESTINATION usr/lib)
 
 target_include_directories(ouroboros PUBLIC ${CMAKE_CURRENT_BINARY_DIR})
diff --git a/src/lib/random.c b/src/lib/random.c
new file mode 100644
index 00000000..d6bde0f8
--- /dev/null
+++ b/src/lib/random.c
@@ -0,0 +1,51 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2017
+ *
+ * Pseudo random generator
+ *
+ *    Dimitri Staessens <dimitri.staessens@ugent.be>
+ *    Sander Vrijders   <sander.vrijders@ugent.be>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <ouroboros/random.h>
+
+#if defined(HAVE_SYS_RANDOM)
+#include <sys/random.h>
+#elif defined(__FreeBSD__)
+#include <stdlib.h>
+#elif defined(HAVE_OPENSSL)
+#include <openssl/rand.h>
+#include <limits.h>
+#endif
+
+int random_buffer(void * buf,
+                  size_t len)
+{
+#if defined(HAVE_SYS_RANDOM)
+        return getrandom(buf, len, GRND_NONBLOCK); /* also in glibc 2.25 */
+#elif defined(__FreeBSD__)
+        return arc4random_buf(buf, len);
+#elif defined(HAVE_OPENSSL)
+        if (len > 0 && len < INT_MAX)
+                return RAND_bytes((unsigned char *) buf, (int) len);
+        return -1;
+#else
+        (void) buf;
+        (void) len;
+        return -1;
+#endif
+}