From b5d287a9cfa9416aba675dd1778838e67efceefc Mon Sep 17 00:00:00 2001
From: lloyd <lloyd@randombit.net>
Date: Sat, 9 Nov 2013 15:56:50 +0000
Subject: Fix EGD settings. Some cleanup and renaming.

---
 src/entropy/proc_walk/proc_walk.cpp | 173 ++++++++++++++++++++++++++++++++++++
 1 file changed, 173 insertions(+)
 create mode 100644 src/entropy/proc_walk/proc_walk.cpp

(limited to 'src/entropy/proc_walk/proc_walk.cpp')

diff --git a/src/entropy/proc_walk/proc_walk.cpp b/src/entropy/proc_walk/proc_walk.cpp
new file mode 100644
index 000000000..050d9dcf7
--- /dev/null
+++ b/src/entropy/proc_walk/proc_walk.cpp
@@ -0,0 +1,173 @@
+/*
+* Entropy source based on reading files in /proc on the assumption
+* that a remote attacker will have difficulty guessing some of them.
+*
+* (C) 1999-2008,2012 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/internal/proc_walk.h>
+#include <botan/secmem.h>
+#include <cstring>
+#include <deque>
+
+#ifndef _POSIX_C_SOURCE
+  #define _POSIX_C_SOURCE 199309
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <fcntl.h>
+
+namespace Botan {
+
+/**
+* Returns file descriptors. Until it doesn't
+*/
+class File_Descriptor_Source
+   {
+   public:
+      /**
+      * @return next file descriptor, or -1 if done
+      */
+      virtual int next_fd() = 0;
+
+      virtual ~File_Descriptor_Source() {}
+   };
+
+namespace {
+
+class Directory_Walker : public File_Descriptor_Source
+   {
+   public:
+      Directory_Walker(const std::string& root) :
+         m_cur_dir(std::make_pair<DIR*, std::string>(nullptr, ""))
+         {
+         if(DIR* root_dir = ::opendir(root.c_str()))
+            m_cur_dir = std::make_pair(root_dir, root);
+         }
+
+      ~Directory_Walker()
+         {
+         if(m_cur_dir.first)
+            ::closedir(m_cur_dir.first);
+         }
+
+      int next_fd();
+   private:
+      void add_directory(const std::string& dirname)
+         {
+         m_dirlist.push_back(dirname);
+         }
+
+      std::pair<struct dirent*, std::string> get_next_dirent();
+
+      std::pair<DIR*, std::string> m_cur_dir;
+      std::deque<std::string> m_dirlist;
+   };
+
+std::pair<struct dirent*, std::string> Directory_Walker::get_next_dirent()
+   {
+   while(m_cur_dir.first)
+      {
+      if(struct dirent* dir = ::readdir(m_cur_dir.first))
+         return std::make_pair(dir, m_cur_dir.second);
+
+      ::closedir(m_cur_dir.first);
+      m_cur_dir = std::make_pair<DIR*, std::string>(nullptr, "");
+
+      while(!m_dirlist.empty() && !m_cur_dir.first)
+         {
+         const std::string next_dir_name = m_dirlist[0];
+         m_dirlist.pop_front();
+
+         if(DIR* next_dir = ::opendir(next_dir_name.c_str()))
+            m_cur_dir = std::make_pair(next_dir, next_dir_name);
+         }
+      }
+
+   return std::make_pair<struct dirent*, std::string>(nullptr, ""); // nothing left
+   }
+
+int Directory_Walker::next_fd()
+   {
+   while(true)
+      {
+      std::pair<struct dirent*, std::string> entry = get_next_dirent();
+
+      if(!entry.first)
+         break; // no more dirs
+
+      const std::string filename = entry.first->d_name;
+
+      if(filename == "." || filename == "..")
+         continue;
+
+      const std::string full_path = entry.second + '/' + filename;
+
+      struct stat stat_buf;
+      if(::lstat(full_path.c_str(), &stat_buf) == -1)
+         continue;
+
+      if(S_ISDIR(stat_buf.st_mode))
+         {
+         add_directory(full_path);
+         }
+      else if(S_ISREG(stat_buf.st_mode) && (stat_buf.st_mode & S_IROTH))
+         {
+         int fd = ::open(full_path.c_str(), O_RDONLY | O_NOCTTY);
+
+         if(fd > 0)
+            return fd;
+         }
+      }
+
+   return -1;
+   }
+
+}
+
+/**
+* ProcWalking_EntropySource Destructor
+*/
+ProcWalking_EntropySource::~ProcWalking_EntropySource()
+   {
+   // for ~unique_ptr
+   }
+
+void ProcWalking_EntropySource::poll(Entropy_Accumulator& accum)
+   {
+   const size_t MAX_FILES_READ_PER_POLL = 2048;
+
+   if(!m_dir)
+      m_dir = new Directory_Walker(m_path);
+
+   secure_vector<byte>& io_buffer = accum.get_io_buffer(4096);
+
+   for(size_t i = 0; i != MAX_FILES_READ_PER_POLL; ++i)
+      {
+      int fd = m_dir->next_fd();
+
+      // If we've exhaused this walk of the directory, halt the poll
+      if(fd == -1)
+         {
+         delete m_dir;
+         m_dir = nullptr;
+         break;
+         }
+
+      ssize_t got = ::read(fd, &io_buffer[0], io_buffer.size());
+      ::close(fd);
+
+      if(got > 0)
+         accum.add(&io_buffer[0], got, .001);
+
+      if(accum.polling_goal_achieved())
+         break;
+      }
+   }
+
+}
-- 
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