Implement brep-monitor

1 files changed, 1005 insertions, 0 deletions

diff --git a/web/server/apache/request.cxx b/web/server/apache/request.cxx
new file mode 100644
index 0000000..a413081
--- /dev/null
+++ b/web/server/apache/request.cxx
@@ -0,0 +1,1005 @@
+// file      : web/server/apache/request.cxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#include <web/server/apache/request.hxx>
+
+#include <apr.h>         // APR_SIZE_MAX
+#include <apr_errno.h>   // apr_status_t, APR_SUCCESS, APR_E*, apr_strerror()
+#include <apr_tables.h>  // apr_table_*, apr_table_*(), apr_array_header_t
+#include <apr_strings.h> // apr_pstrdup()
+#include <apr_buckets.h> // apr_bucket*, apr_bucket_*(), apr_brigade_*(),
+                         // APR_BRIGADE_*()
+
+#include <httpd.h>         // request_rec, HTTP_*, OK
+#include <http_protocol.h> // ap_*()
+
+#include <apreq2/apreq.h>        // APREQ_*
+#include <apreq2/apreq_util.h>   // apreq_brigade_copy()
+#include <apreq2/apreq_param.h>  // apreq_param_t, apreq_value_to_param()
+#include <apreq2/apreq_parser.h> // apreq_parser_t, apreq_parser_make()
+
+#include <ctime>     // strftime(), time_t
+#include <vector>
+#include <chrono>
+#include <memory>    // unique_ptr
+#include <string>
+#include <cassert>
+#include <ostream>
+#include <istream>
+#include <cstring>   // str*(), memcpy(), size_t
+#include <utility>   // move()
+#include <iterator>  // istreambuf_iterator
+#include <stdexcept> // invalid_argument, runtime_error
+#include <exception> // current_exception()
+#include <streambuf>
+#include <algorithm> // min()
+
+#include <libbutl/utility.mxx>   // icasecmp()
+#include <libbutl/optional.mxx>
+#include <libbutl/timestamp.mxx>
+
+#include <web/server/mime-url-encoding.hxx>
+
+using namespace std;
+using namespace butl;
+
+namespace web
+{
+  namespace apache
+  {
+    [[noreturn]] static void
+    throw_internal_error (apr_status_t s, const string& what)
+    {
+      char buf[1024];
+      throw runtime_error (what + ": " + apr_strerror (s, buf, sizeof (buf)));
+    }
+
+    // Extend the Apache stream with checking for the read limit and caching
+    // the content if requested. Replay the cached content after rewind.
+    //
+    class istreambuf_cache: public istreambuf
+    {
+      enum class mode
+      {
+        cache,  // Read from Apache stream, save the read data into the cache.
+        replay, // Read from the cache.
+        proxy   // Read from Apache stream (don't save into the cache).
+      };
+
+    public:
+      istreambuf_cache (size_t read_limit, size_t cache_limit,
+                        request_rec* r,
+                        stream_state& s,
+                        size_t bufsize = 1024,
+                        size_t putback = 1)
+          : istreambuf (r, s, bufsize, putback),
+            read_limit_ (read_limit),
+            cache_limit_ (cache_limit)
+      {
+      }
+
+      void
+      rewind ()
+      {
+        // Fail if some content is already missed in the cache.
+        //
+        if (mode_ == mode::proxy)
+          throw sequence_error (
+            string ("web::apache::istreambuf_cache::rewind: ") +
+            (cache_limit_ > 0
+             ? "half-buffered"
+             : "unbuffered"));
+
+        mode_ = mode::replay;
+        replay_pos_ = 0;
+        setg (nullptr, nullptr, nullptr);
+      }
+
+      void
+      limits (size_t read_limit, size_t cache_limit)
+      {
+        if (read_limit > 0)
+          read_limit_ = read_limit;
+
+        if (cache_limit > 0)
+        {
+          // We can not increase the cache limit if some content is already
+          // missed in the cache.
+          //
+          if (cache_limit > cache_limit_ && mode_ == mode::proxy)
+            throw sequence_error (
+              "web::apache::istreambuf_cache::limits: unbuffered");
+
+          cache_limit_ = cache_limit;
+        }
+      }
+
+      size_t read_limit  () const noexcept {return read_limit_;}
+      size_t cache_limit () const noexcept {return cache_limit_;}
+
+    private:
+      virtual int_type
+      underflow ();
+
+    private:
+      // Limits
+      //
+      size_t read_limit_;
+      size_t cache_limit_;
+
+      // State
+      //
+      mode mode_ = mode::cache;
+      size_t read_bytes_ = 0;
+      bool eof_ = false;        // End of Apache stream is reached.
+
+      // Cache
+      //
+      struct chunk
+      {
+        vector<char> data;
+        size_t offset;
+
+        chunk (vector<char>&& d, size_t o): data (move (d)), offset (o) {}
+
+        // Make the type move constructible-only to avoid copying of chunks on
+        // vector growth.
+        //
+        chunk (chunk&&) = default;
+      };
+
+      vector<chunk> cache_;
+      size_t cache_size_ = 0;
+      size_t replay_pos_ = 0;
+    };
+
+    istreambuf_cache::int_type istreambuf_cache::
+    underflow ()
+    {
+      if (gptr () < egptr ())
+        return traits_type::to_int_type (*gptr ());
+
+      if (mode_ == mode::replay)
+      {
+        if (replay_pos_ < cache_.size ())
+        {
+          chunk& ch (cache_[replay_pos_++]);
+          char*  p  (ch.data.data ());
+          setg (p, p + ch.offset, p + ch.data.size ());
+          return traits_type::to_int_type (*gptr ());
+        }
+
+        // No more data to replay, so switch to the cache mode. That includes
+        // resetting eback, gptr and egptr, so they point into the istreambuf's
+        // internal buffer. Putback area should also be restored.
+        //
+        mode_ = mode::cache;
+
+        // Bail out if the end of stream is reached.
+        //
+        if (eof_)
+          return traits_type::eof ();
+
+        char* p (buf_.data () + putback_);
+        size_t pb (0);
+
+        // Restore putback area if there is any cached data. Thanks to
+        // istreambuf, it's all in a single chunk.
+        //
+        if (!cache_.empty ())
+        {
+          chunk& ch (cache_.back ());
+          pb = min (putback_, ch.data.size ());
+          memcpy (p - pb, ch.data.data () + ch.data.size () - pb, pb);
+        }
+
+        setg (p - pb, p, p);
+      }
+
+      // Delegate reading to the base class in the cache or proxy modes, but
+      // check for the read limit first.
+      //
+      if (read_limit_ && read_bytes_ >= read_limit_)
+        throw invalid_request (HTTP_REQUEST_ENTITY_TOO_LARGE,
+                               "payload too large");
+
+      // Throws the sequence_error exception if some unbuffered content is
+      // already written.
+      //
+      int_type r (istreambuf::underflow ());
+
+      if (r == traits_type::eof ())
+      {
+        eof_ = true;
+        return r;
+      }
+
+      // Increment the read bytes counter.
+      //
+      size_t rb (egptr () - gptr ());
+      read_bytes_ += rb;
+
+      // In the cache mode save the read data if the cache limit is not
+      // reached, otherwise switch to the proxy mode.
+      //
+      if (mode_ == mode::cache)
+      {
+        // Not to complicate things we will copy the buffer into the cache
+        // together with the putback area, which is OK as it usually takes a
+        // small fraction of the buffer. By the same reason we will cache the
+        // whole data read even though we can exceed the limits by
+        // bufsize - putback - 1 bytes.
+        //
+        if (cache_size_ < cache_limit_)
+        {
+          chunk ch (vector<char> (eback (), egptr ()),
+                    static_cast<size_t> (gptr () - eback ()));
+
+          cache_.emplace_back (move (ch));
+          cache_size_ += rb;
+        }
+        else
+          mode_ = mode::proxy;
+      }
+
+      return r;
+    }
+
+    // Stream interface for reading from the Apache's bucket brigade. Put back
+    // is not supported.
+    //
+    // Note that reading from a brigade bucket modifies the brigade in the
+    // general case. For example, reading from a file bucket adds a new heap
+    // bucket before the file bucket on every read. Traversing/reading through
+    // such a bucket brigade effectively loads the whole file into the memory,
+    // so the subsequent brigade traversal results in iterating over the
+    // loaded heap buckets.
+    //
+    // To avoid such a behavior we will make a shallow copy of the original
+    // bucket brigade, initially and for each rewind. Then, instead of
+    // iterating, we will always read from the first bucket removing it after
+    // the use.
+    //
+    class istreambuf_buckets: public streambuf
+    {
+    public:
+      // The bucket brigade must exist during the object's lifetime.
+      //
+      explicit
+      istreambuf_buckets (const apr_bucket_brigade* bs)
+          : orig_buckets_ (bs),
+            buckets_ (apr_brigade_create (bs->p, bs->bucket_alloc))
+
+      {
+        if (buckets_ == nullptr)
+          throw_internal_error (APR_ENOMEM, "apr_brigade_create");
+
+        rewind (); // Copy the original buckets.
+      }
+
+      void
+      rewind ()
+      {
+        // Note that apreq_brigade_copy() appends buckets to the destination,
+        // so we clean it up first.
+        //
+        apr_status_t r (apr_brigade_cleanup (buckets_.get ()));
+        if (r != APR_SUCCESS)
+          throw_internal_error (r, "apr_brigade_cleanup");
+
+        r = apreq_brigade_copy (
+          buckets_.get (),
+          const_cast<apr_bucket_brigade*> (orig_buckets_));
+
+        if (r != APR_SUCCESS)
+          throw_internal_error (r, "apreq_brigade_copy");
+
+        setg (nullptr, nullptr, nullptr);
+      }
+
+    private:
+      virtual int_type
+      underflow ()
+      {
+        if (gptr () < egptr ())
+          return traits_type::to_int_type (*gptr ());
+
+        // If the get-pointer is not NULL then it points to the data referred
+        // by the first brigade bucket. As we will bail out or rewrite such a
+        // pointer now there is no need for the bucket either, so we can
+        // safely delete it.
+        //
+        if (gptr () != nullptr)
+        {
+          assert (!APR_BRIGADE_EMPTY (buckets_));
+
+          // Note that apr_bucket_delete() is a macro and the following
+          // call ends up badly (with SIGSEGV).
+          //
+          // apr_bucket_delete (APR_BRIGADE_FIRST (buckets_));
+          //
+          apr_bucket* b (APR_BRIGADE_FIRST (buckets_));
+          apr_bucket_delete (b);
+        }
+
+        if (APR_BRIGADE_EMPTY (buckets_))
+          return traits_type::eof ();
+
+        apr_size_t n;
+        const char* d;
+        apr_bucket* b (APR_BRIGADE_FIRST (buckets_));
+        apr_status_t r (apr_bucket_read (b, &d, &n, APR_BLOCK_READ));
+
+        if (r != APR_SUCCESS)
+          throw_internal_error (r, "apr_bucket_read");
+
+        char* p (const_cast<char*> (d));
+        setg (p, p, p + n);
+        return traits_type::to_int_type (*gptr ());
+      }
+
+    private:
+      const apr_bucket_brigade* orig_buckets_;
+
+      struct brigade_deleter
+      {
+        void operator() (apr_bucket_brigade* p) const
+        {
+          if (p != nullptr)
+          {
+            apr_status_t r (apr_brigade_destroy (p));
+
+            // Shouldn't fail unless something is severely damaged.
+            //
+            assert (r == APR_SUCCESS);
+          }
+        }
+      };
+
+      unique_ptr<apr_bucket_brigade, brigade_deleter> buckets_;
+    };
+
+    class istream_buckets_base
+    {
+    public:
+      explicit
+      istream_buckets_base (const apr_bucket_brigade* bs): buf_ (bs) {}
+
+    protected:
+      istreambuf_buckets buf_;
+    };
+
+    class istream_buckets: public istream_buckets_base, public istream
+    {
+    public:
+      explicit
+      istream_buckets (const apr_bucket_brigade* bs)
+          // Note that calling dtor for istream object before init() is called
+          // is undefined behavior. That's the reason for inventing the
+          // istream_buckets_base class.
+          //
+          : istream_buckets_base (bs), istream (&buf_)
+      {
+        exceptions (failbit | badbit);
+      }
+
+      void
+      rewind ()
+      {
+        buf_.rewind ();
+        clear ();       // Clears *bit flags (in particular eofbit).
+      }
+    };
+
+    // request
+    //
+    request::
+    request (request_rec* rec) noexcept
+      : rec_ (rec)
+    {
+      rec_->status = HTTP_OK;
+    }
+
+    request::
+    ~request ()
+    {
+    }
+
+    void request::
+    state (request_state s)
+    {
+      assert (s != request_state::initial);
+
+      if (s == state_)
+        return; // Noop.
+
+      if (s < state_)
+      {
+        // Can't "unwind" irrevocable interaction with Apache API.
+        //
+        static const char* names[] = {
+          "initial", "reading", "headers", "writing"};
+
+        string str ("web::apache::request::set_state: ");
+        str += names[static_cast<size_t> (state_)];
+        str += " to ";
+        str += names[static_cast<size_t> (s)];
+
+        throw sequence_error (move (str));
+      }
+
+      if (s == request_state::reading)
+      {
+        // Prepare request content for reading.
+        //
+        int r (ap_setup_client_block (rec_, REQUEST_CHUNKED_DECHUNK));
+
+        if (r != OK)
+          throw invalid_request (r);
+      }
+      else if (s > request_state::reading && state_ <= request_state::reading)
+      {
+        // Read request content if any, discard whatever is received.
+        //
+        int r (ap_discard_request_body (rec_));
+
+        if (r != OK)
+          throw invalid_request (r);
+      }
+
+      state_ = s;
+    }
+
+    void request::
+    rewind ()
+    {
+      // @@ Response cookies buffering is not supported yet. When done will be
+      //    possible to rewind in broader range of cases.
+      //
+      if (state_ > request_state::reading)
+        throw sequence_error ("web::apache::request::rewind: unbuffered");
+
+      out_.reset ();
+      out_buf_.reset ();
+
+      rec_->status = HTTP_OK;
+
+      ap_set_content_type (rec_, nullptr); // Unset the output content type.
+
+      // We don't need to rewind the input stream (which well may fail if
+      // unbuffered) if the form data is already read.
+      //
+      if (in_ != nullptr && form_data_ == nullptr)
+      {
+        assert (in_buf_ != nullptr);
+
+        in_buf_->rewind (); // Throws if impossible to rewind.
+        in_->clear ();      // Clears *bit flags (in particular eofbit).
+      }
+
+      // Rewind uploaded file streams.
+      //
+      if (uploads_ != nullptr)
+      {
+        for (const unique_ptr<istream_buckets>& is: *uploads_)
+        {
+          if (is != nullptr)
+            is->rewind ();
+        }
+      }
+    }
+
+    istream& request::
+    content (size_t limit, size_t buffer)
+    {
+      // Create the input stream/streambuf if not present, otherwise adjust the
+      // limits.
+      //
+      if (in_ == nullptr)
+      {
+        unique_ptr<istreambuf_cache> in_buf (
+          new istreambuf_cache (limit, buffer, rec_, *this));
+
+        in_.reset (new istream (in_buf.get ()));
+        in_buf_ = move (in_buf);
+        in_->exceptions (istream::failbit | istream::badbit);
+      }
+      else
+      {
+        assert (in_buf_ != nullptr);
+        in_buf_->limits (limit, buffer);
+      }
+
+      return *in_;
+    }
+
+    const path& request::
+    path ()
+    {
+      if (path_.empty ())
+      {
+        path_ = path_type (rec_->uri); // Is already URL-decoded.
+
+        // Module request handler can not be called if URI is empty.
+        //
+        assert (!path_.empty ());
+      }
+
+      return path_;
+    }
+
+    const name_values& request::
+    parameters (size_t limit, bool url_only)
+    {
+      if (parameters_ == nullptr || url_only < url_only_parameters_)
+      {
+        try
+        {
+          if (parameters_ == nullptr)
+          {
+            parameters_.reset (new name_values ());
+            parse_url_parameters (rec_->args);
+          }
+
+          if (!url_only && form_data (limit))
+          {
+            // After the form data is parsed we can clean it up for the
+            // application/x-www-form-urlencoded encoding but not for the
+            // multipart/form-data (see parse_multipart_parameters() for
+            // details).
+            //
+            if (form_multipart_)
+              parse_multipart_parameters (*form_data_);
+            else
+            {
+              // Make the character vector a NULL-terminated string.
+              //
+              form_data_->push_back ('\0');
+
+              parse_url_parameters (form_data_->data ());
+              *form_data_ = vector<char> (); // Reset the cache.
+            }
+          }
+        }
+        catch (const invalid_argument&)
+        {
+          throw invalid_request ();
+        }
+
+        url_only_parameters_ = url_only;
+      }
+
+      return *parameters_;
+    }
+
+    bool request::
+    form_data (size_t limit)
+    {
+      if (form_data_ == nullptr)
+      {
+        form_data_.reset (new vector<char> ());
+
+        // We will not consider POST body as a form data if the request is in
+        // the reading or later state.
+        //
+        if (rec_->method_number == M_POST && state_ < request_state::reading)
+        {
+          const char* ct (apr_table_get (rec_->headers_in, "Content-Type"));
+
+          if (ct != nullptr)
+          {
+            form_multipart_ = icasecmp ("multipart/form-data", ct, 19) == 0;
+
+            if (form_multipart_ ||
+                icasecmp ("application/x-www-form-urlencoded", ct, 33) == 0)
+              *form_data_ = vector<char> (
+                istreambuf_iterator<char> (content (limit)),
+                istreambuf_iterator<char> ());
+          }
+        }
+      }
+
+      return !form_data_->empty ();
+    }
+
+    void request::
+    parse_url_parameters (const char* args)
+    {
+      assert (parameters_ != nullptr);
+
+      for (auto n (args); n != nullptr; )
+      {
+        const char* v (strchr (n, '='));
+        const char* e (strchr (n, '&'));
+
+        if (e != nullptr && e < v)
+          v = nullptr;
+
+        string name (v != nullptr
+                     ? mime_url_decode (n, v) :
+                     (e
+                      ? mime_url_decode (n, e)
+                      : mime_url_decode (n, n + strlen (n))));
+
+        optional<string> value;
+
+        if (v++)
+          value = e
+            ? mime_url_decode (v, e)
+            : mime_url_decode (v, v + strlen (v));
+
+        if (!name.empty () || value)
+          parameters_->emplace_back (move (name), move (value));
+
+        n = e ? e + 1 : nullptr;
+      }
+    }
+
+    void request::
+    parse_multipart_parameters (const vector<char>& body)
+    {
+      assert (parameters_ != nullptr && uploads_ == nullptr);
+
+      auto throw_bad_request = [] (apr_status_t s,
+                                   status_code sc = HTTP_BAD_REQUEST)
+      {
+        char buf[1024];
+        throw invalid_request (sc, apr_strerror (s, buf, sizeof (buf)));
+      };
+
+      // Create the file upload stream list, filling it with NULLs for the
+      // parameters parsed from the URL query part.
+      //
+      uploads_.reset (
+        new vector<unique_ptr<istream_buckets>> (parameters_->size ()));
+
+      // All the required objects (parser, input/output buckets, etc.) will be
+      // allocated in the request memory pool and so will have the HTTP
+      // request duration lifetime.
+      //
+      apr_pool_t* pool (rec_->pool);
+
+      // Create the input bucket brigade containing a single bucket that
+      // references the form data.
+      //
+      apr_bucket_alloc_t* ba (apr_bucket_alloc_create (pool));
+      if (ba == nullptr)
+        throw_internal_error (APR_ENOMEM, "apr_bucket_alloc_create");
+
+      apr_bucket_brigade* bb (apr_brigade_create (pool, ba));
+      if (bb == nullptr)
+        throw_internal_error (APR_ENOMEM, "apr_brigade_create");
+
+      apr_bucket* b (
+        apr_bucket_immortal_create (body.data (), body.size (), ba));
+
+      if (b == nullptr)
+        throw_internal_error (APR_ENOMEM, "apr_bucket_immortal_create");
+
+      APR_BRIGADE_INSERT_TAIL (bb, b);
+
+      if ((b = apr_bucket_eos_create (ba)) == nullptr)
+        throw_internal_error (APR_ENOMEM, "apr_bucket_eos_create");
+
+      APR_BRIGADE_INSERT_TAIL (bb, b);
+
+      // Make sure that the parser will not swap the parsed data to disk
+      // passing the maximum possible value for the brigade limit. This way
+      // the resulting buckets will reference the form data directly, making
+      // no copies. This why we should not reset the form data cache after
+      // the parsing.
+      //
+      // Note that in future we may possibly setup the parser to read from the
+      // Apache internals directly and enable swapping the data to disk to
+      // minimize memory consumption.
+      //
+      apreq_parser_t* parser (
+        apreq_parser_make (pool,
+                           ba,
+                           apr_table_get (rec_->headers_in, "Content-Type"),
+                           apreq_parse_multipart,
+                           APR_SIZE_MAX /* brigade_limit */,
+                           nullptr /* temp_dir */,
+                           nullptr /* hook */,
+                           nullptr /* ctx */));
+
+      if (parser == nullptr)
+        throw_internal_error (APR_ENOMEM, "apreq_parser_make");
+
+      // Create the output table that will be filled with the parsed
+      // parameters.
+      //
+      apr_table_t* params (apr_table_make (pool, APREQ_DEFAULT_NELTS));
+      if (params == nullptr)
+        throw_internal_error (APR_ENOMEM, "apr_table_make");
+
+      // Parse the form data.
+      //
+      apr_status_t r (apreq_parser_run (parser, params, bb));
+      if (r != APR_SUCCESS)
+        throw_bad_request (r);
+
+      // Fill the parameter and file upload stream lists.
+      //
+      const apr_array_header_t* ps (apr_table_elts (params));
+      size_t n (ps->nelts);
+
+      for (auto p (reinterpret_cast<const apr_table_entry_t*> (ps->elts));
+           n--; ++p)
+      {
+        assert (p->key != nullptr && p->val != nullptr);
+
+        if (*p->key != '\0')
+        {
+          parameters_->emplace_back (p->key, optional<string> (p->val));
+
+          const apreq_param_t* ap (apreq_value_to_param (p->val));
+          assert (ap != nullptr); // Must always be resolvable.
+
+          uploads_->emplace_back (ap->upload != nullptr
+                                  ? new istream_buckets (ap->upload)
+                                  : nullptr);
+        }
+      }
+    }
+
+    request::uploads_type& request::
+    uploads () const
+    {
+      if (parameters_ == nullptr || url_only_parameters_)
+        sequence_error ("web::apache::request::uploads");
+
+      if (uploads_ == nullptr)
+        throw invalid_argument ("no uploads");
+
+      assert (uploads_->size () == parameters_->size ());
+      return *uploads_;
+    }
+
+    istream& request::
+    open_upload (size_t index)
+    {
+      uploads_type& us (uploads ());
+      size_t n (us.size ());
+
+      if (index >= n)
+        throw invalid_argument ("invalid index");
+
+      const unique_ptr<istream_buckets>& is (us[index]);
+
+      if (is == nullptr)
+        throw invalid_argument ("no upload");
+
+      return *is;
+    }
+
+    istream& request::
+    open_upload (const string& name)
+    {
+      uploads_type& us (uploads ());
+      size_t n (us.size ());
+
+      istream* r (nullptr);
+      for (size_t i (0); i < n; ++i)
+      {
+        if ((*parameters_)[i].name == name)
+        {
+          istream* is (us[i].get ());
+
+          if (is != nullptr)
+          {
+            if (r != nullptr)
+              throw invalid_argument ("multiple uploads for '" + name + "'");
+
+            r = is;
+          }
+        }
+      }
+
+      if (r == nullptr)
+        throw invalid_argument ("no upload");
+
+      return *r;
+    }
+
+    const name_values& request::
+    headers ()
+    {
+      if (headers_ == nullptr)
+      {
+        headers_.reset (new name_values ());
+
+        const apr_array_header_t* ha (apr_table_elts (rec_->headers_in));
+        size_t n (ha->nelts);
+
+        headers_->reserve (n + 1); // One for the custom :Client-IP header.
+
+        auto add = [this] (const char* n, const char* v)
+        {
+          assert (n != nullptr && v != nullptr);
+          headers_->emplace_back (n, optional<string> (v));
+        };
+
+        for (auto h (reinterpret_cast<const apr_table_entry_t*> (ha->elts));
+             n--; ++h)
+          add (h->key, h->val);
+
+        assert (rec_->connection != nullptr);
+
+        add (":Client-IP", rec_->connection->client_ip);
+      }
+
+      return *headers_;
+    }
+
+    const name_values& request::
+    cookies ()
+    {
+      if (cookies_ == nullptr)
+      {
+        cookies_.reset (new name_values ());
+
+        const apr_array_header_t* ha (apr_table_elts (rec_->headers_in));
+        size_t n (ha->nelts);
+
+        for (auto h (reinterpret_cast<const apr_table_entry_t*> (ha->elts));
+             n--; ++h)
+        {
+          assert (h->key != nullptr);
+
+          if (icasecmp (h->key, "Cookie") == 0)
+          {
+            for (const char* n (h->val); n != nullptr; )
+            {
+              const char* v (strchr (n, '='));
+              const char* e (strchr (n, ';'));
+
+              if (e != nullptr && e < v)
+                v = nullptr;
+
+              string name (v != nullptr
+                           ? mime_url_decode (n, v, true)
+                           : (e
+                              ? mime_url_decode (n, e, true)
+                              : mime_url_decode (n, n + strlen (n), true)));
+
+              optional<string> value;
+
+              if (v++)
+                value = e
+                  ? mime_url_decode (v, e, true)
+                  : mime_url_decode (v, v + strlen (v), true);
+
+              if (!name.empty () || value)
+                cookies_->emplace_back (move (name), move (value));
+
+              n = e ? e + 1 : nullptr;
+            }
+          }
+        }
+      }
+
+      return *cookies_;
+    }
+
+    ostream& request::
+    content (status_code status, const string& type, bool buffer)
+    {
+      if (out_ &&
+
+          // Same status code.
+          //
+          status == rec_->status &&
+
+          // Same buffering flag.
+          //
+          buffer ==
+          (dynamic_cast<stringbuf*> (out_buf_.get ()) != nullptr) &&
+
+          // Same content type.
+          //
+          icasecmp (type, rec_->content_type ? rec_->content_type : "") == 0)
+      {
+        // No change, return the existing stream.
+        //
+        return *out_;
+      }
+
+      if (state_ >= request_state::writing)
+        throw sequence_error ("web::apache::request::content");
+
+      if (!buffer)
+        // Request body will be discarded prior first byte of content is
+        // written. Save form data now to make it available for future
+        // parameters() call.
+        //
+        // In the rare cases when the form data is expectedly bigger than 64K
+        // the client can always call parameters(limit) explicitly.
+        //
+        form_data (64 * 1024);
+
+      unique_ptr<streambuf> out_buf (
+        buffer
+        ? static_cast<streambuf*> (new stringbuf ())
+        : static_cast<streambuf*> (new ostreambuf (rec_, *this)));
+
+      out_.reset (new ostream (out_buf.get ()));
+      out_buf_ = move (out_buf);
+      out_->exceptions (ostream::eofbit | ostream::failbit | ostream::badbit);
+
+      rec_->status = status;
+
+      ap_set_content_type (
+        rec_,
+        type.empty () ? nullptr : apr_pstrdup (rec_->pool, type.c_str ()));
+
+      return *out_;
+    }
+
+    void request::
+    status (status_code status)
+    {
+      if (status != rec_->status)
+      {
+        // Setting status code in exception handler is a common usecase
+        // where no sense to throw but still need to signal apache a
+        // proper status code.
+        //
+        if (state_ >= request_state::writing && !current_exception ())
+          throw sequence_error ("web::apache::request::status");
+
+        rec_->status = status;
+        out_.reset ();
+        out_buf_.reset ();
+        ap_set_content_type (rec_, nullptr);
+      }
+    }
+
+    void request::
+    cookie (const char* name,
+            const char* value,
+            const chrono::seconds* max_age,
+            const char* path,
+            const char* domain,
+            bool secure,
+            bool buffer)
+    {
+      assert (!buffer); // Cookie buffering is not implemented yet.
+
+      string s (mime_url_encode (name));
+      s += "=";
+      s += mime_url_encode (value);
+
+      if (max_age)
+      {
+        timestamp tp (system_clock::now () + *max_age);
+        time_t t (system_clock::to_time_t (tp));
+
+        // Assume global locale is not changed and still "C".
+        //
+        char b[100];
+        strftime (b, sizeof (b), "%a, %d-%b-%Y %H:%M:%S GMT", gmtime (&t));
+        s += "; Expires=";
+        s += b;
+      }
+
+      if (path)
+      {
+        s += ";Path=";
+        s += path;
+      }
+
+      if (domain)
+      {
+        s += ";Domain=";
+        s += domain;
+      }
+
+      if (secure)
+        s += ";Secure";
+
+      state (request_state::headers);
+      apr_table_add (rec_->err_headers_out, "Set-Cookie", s.c_str ());
+    }
+  }
+}