Add a new module, es_dev, that will replace es_file. Instead of using C++

iostreams, it uses unbuffered Unix I/O syscalls and is careful to avoid
blocking for more than short amounts of time.

3 files changed, 153 insertions, 0 deletions

diff --git a/modules/es_dev/es_dev.cpp b/modules/es_dev/es_dev.cpp
new file mode 100644
index 000000000..7a61a48af
--- /dev/null
+++ b/modules/es_dev/es_dev.cpp
@@ -0,0 +1,118 @@
+/*************************************************
+* Device EntropySource Source File               *
+* (C) 1999-2007 The Botan Project                *
+*************************************************/
+
+#include <botan/es_dev.h>
+#include <botan/config.h>
+#include <sys/select.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/fcntl.h>
+#include <unistd.h>
+
+namespace Botan {
+
+namespace {
+
+/*************************************************
+* A class handling reading from a device         *
+*************************************************/
+class Device_Reader
+   {
+   public:
+      typedef int fd_type;
+
+      Device_Reader(fd_type device_fd) : fd(device_fd) {}
+      ~Device_Reader() { close(fd); }
+      u32bit get(byte out[], u32bit length);
+
+      static fd_type open(const std::string& pathname);
+   private:
+      fd_type fd;
+   };
+
+/*************************************************
+* Read from a device file                        *
+*************************************************/
+u32bit Device_Reader::get(byte out[], u32bit length)
+   {
+   if(fd < 0)
+      return 0;
+
+   if(fd >= FD_SETSIZE)
+      return 0;
+
+   const u32bit READ_WAIT_MS = 10;
+
+   fd_set read_set;
+   FD_ZERO(&read_set);
+   FD_SET(fd, &read_set);
+
+   struct timeval timeout;
+   timeout.tv_sec = 0;
+   timeout.tv_usec = READ_WAIT_MS * 1000;
+
+   if(::select(fd + 1, &read_set, 0, 0, &timeout) < 0)
+      return 0;
+
+   if(!(FD_ISSET(fd, &read_set)))
+      return 0;
+
+   const ssize_t got = ::read(fd, out, length);
+   if(got <= 0)
+      return 0;
+
+   const u32bit ret = static_cast<u32bit>(got);
+
+   if(ret > length)
+      return 0;
+
+   return ret;
+   }
+
+/*************************************************
+* Attempt to open a device                       *
+*************************************************/
+int Device_Reader::open(const std::string& pathname)
+   {
+#ifndef O_NONBLOCK
+  #define O_NONBLOCK 0
+#endif
+
+#ifndef O_NOCTTY
+  #define O_NOCTTY 0
+#endif
+
+   const int flags = O_RDONLY | O_NONBLOCK | O_NOCTTY;
+   return ::open(pathname.c_str(), flags);
+   }
+
+}
+
+/*************************************************
+* Gather entropy from a RNG device               *
+*************************************************/
+u32bit Device_EntropySource::slow_poll(byte output[], u32bit length)
+   {
+   std::vector<std::string> sources =
+      global_config().option_as_list("rng/es_files");
+
+   u32bit read = 0;
+
+   for(size_t j = 0; j != sources.size(); ++j)
+      {
+      const std::string source = sources[j];
+
+      Device_Reader reader(Device_Reader::open(source));
+
+      read += reader.get(output + read, length - read);
+
+      if(read == length)
+         break;
+      }
+
+   return read;
+   }
+
+}
diff --git a/modules/es_dev/es_dev.h b/modules/es_dev/es_dev.h
new file mode 100644
index 000000000..d491a7b18
--- /dev/null
+++ b/modules/es_dev/es_dev.h
@@ -0,0 +1,24 @@
+/*************************************************
+* Device EntropySource Header File               *
+* (C) 1999-2007 The Botan Project                *
+*************************************************/
+
+#ifndef BOTAN_ENTROPY_SRC_DEVICE_H__
+#define BOTAN_ENTROPY_SRC_DEVICE_H__
+
+#include <botan/base.h>
+
+namespace Botan {
+
+/*************************************************
+* Device Based Entropy Source                    *
+*************************************************/
+class Device_EntropySource : public EntropySource
+   {
+   public:
+      u32bit slow_poll(byte[], u32bit);
+   };
+
+}
+
+#endif
diff --git a/modules/es_dev/modinfo.txt b/modules/es_dev/modinfo.txt
new file mode 100644
index 000000000..3a766013d
--- /dev/null
+++ b/modules/es_dev/modinfo.txt
@@ -0,0 +1,11 @@
+realname "RNG Device Reader"
+
+define ENTROPY_SRC_DEVICE
+
+load_on auto
+modset unix
+
+<add>
+es_dev.h
+es_dev.cpp
+</add>