From 35359f038f571dc46de3d14af72a2bc911fb0a24 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Wed, 18 Mar 2020 22:17:49 +0300
Subject: Implement brep-monitor

---
 web/server/apache/service.cxx | 268 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 268 insertions(+)
 create mode 100644 web/server/apache/service.cxx

(limited to 'web/server/apache/service.cxx')

diff --git a/web/server/apache/service.cxx b/web/server/apache/service.cxx
new file mode 100644
index 0000000..9fb23da
--- /dev/null
+++ b/web/server/apache/service.cxx
@@ -0,0 +1,268 @@
+// file      : web/server/apache/service.cxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#include <web/server/apache/service.hxx>
+
+#include <apr_pools.h> // apr_palloc()
+
+#include <httpd.h>       // server_rec
+#include <http_config.h> // command_rec, cmd_*, ap_get_module_config()
+
+#include <memory>    // unique_ptr
+#include <string>
+#include <cassert>
+#include <utility>   // move()
+#include <cstring>   // strlen(), strcmp()
+#include <exception>
+
+#include <libbutl/utility.mxx>  // function_cast()
+#include <libbutl/optional.mxx>
+
+#include <web/server/module.hxx>
+#include <web/server/apache/log.hxx>
+
+using namespace std;
+using namespace butl;
+
+namespace web
+{
+  namespace apache
+  {
+    void service::
+    init_directives ()
+    {
+      assert (cmds == nullptr);
+
+      // Fill apache module directive definitions. Directives share common
+      // name space in apache configuration file, so to prevent name clash
+      // have to form directive name as a combination of module and option
+      // names: <module name>-<option name>. This why for option bar of module
+      // foo the corresponding directive will appear in apache configuration
+      // file as foo-bar.
+      //
+      const option_descriptions& od (exemplar_.options ());
+      unique_ptr<command_rec[]> directives (new command_rec[od.size () + 2]);
+      command_rec* d (directives.get ());
+
+      for (const auto& o: od)
+      {
+        auto i (
+          option_descriptions_.emplace (name_ + "-" + o.first, o.second));
+        assert (i.second);
+
+        *d++ =
+          {
+            i.first->first.c_str (),
+            function_cast<cmd_func> (parse_option),
+            this,
+
+            // Allow directives in both server and directory configuration
+            // scopes.
+            //
+            RSRC_CONF | ACCESS_CONF,
+
+            // Move away from TAKE1 to be able to handle empty string and
+            // no-value.
+            //
+            RAW_ARGS,
+
+            nullptr
+          };
+      }
+
+      // Track if the handler is allowed to handle a request in the specific
+      // configuration scope. The handler exemplar will be created (and
+      // initialized) only for configuration contexts that have
+      // 'SetHandler <mod_name>' in effect for the corresponding scope.
+      //
+      *d++ =
+        {
+          "SetHandler",
+          function_cast<cmd_func> (parse_option),
+          this,
+          RSRC_CONF | ACCESS_CONF,
+          RAW_ARGS,
+          nullptr
+        };
+
+      *d = {nullptr, nullptr, nullptr, 0, RAW_ARGS, nullptr};
+      cmds = directives.release ();
+    }
+
+    void* service::
+    create_server_context (apr_pool_t* pool, server_rec*) noexcept
+    {
+      // Create the object using the configuration memory pool provided by the
+      // Apache API. The lifetime of the object is equal to the lifetime of
+      // the pool.
+      //
+      void* p (apr_palloc (pool, sizeof (context)));
+      assert (p != nullptr);
+      return new (p) context ();
+    }
+
+    void* service::
+    create_dir_context (apr_pool_t* pool, char* dir) noexcept
+    {
+      // Create the object using the configuration memory pool provided by the
+      // Apache API. The lifetime of the object is equal to the lifetime of
+      // the pool.
+      //
+      void* p (apr_palloc (pool, sizeof (context)));
+      assert (p != nullptr);
+
+      // For the user-defined directory configuration context dir is the path
+      // of the corresponding directive. For the special server directory
+      // invented by Apache for server scope directives, dir is NULL.
+      //
+      return new (p) context (dir == nullptr);
+    }
+
+    const char* service::
+    parse_option (cmd_parms* parms, void* conf, const char* args) noexcept
+    {
+      service& srv (*reinterpret_cast<service*> (parms->cmd->cmd_data));
+
+      if (srv.options_parsed_)
+        // Apache have started the second pass of its messy initialization
+        // cycle (more details at http://wiki.apache.org/httpd/ModuleLife).
+        // This time we are parsing for real. Cleanup the existing config, and
+        // start building the new one.
+        //
+        srv.clear_config ();
+
+      // 'args' is an optionally double-quoted string. It uses double quotes
+      // to distinguish empty string from no-value case.
+      //
+      assert (args != nullptr);
+
+      optional<string> value;
+      if (auto l = strlen (args))
+        value = l >= 2 && args[0] == '"' && args[l - 1] == '"'
+          ? string (args + 1, l - 2)
+          : args;
+
+      // Determine the directory and server configuration contexts for the
+      // option.
+      //
+      context* dir_context (context_cast (conf));
+      assert (dir_context != nullptr);
+
+      server_rec* server (parms->server);
+      assert (server != nullptr);
+      assert (server->module_config != nullptr);
+
+      context* srv_context (
+        context_cast (ap_get_module_config (server->module_config, &srv)));
+
+      assert (srv_context != nullptr);
+
+      // Associate the directory configuration context with the enclosing
+      // server configuration context.
+      //
+      context*& s (dir_context->server);
+      if (s == nullptr)
+        s = srv_context;
+      else
+        assert (s == srv_context);
+
+      // If the option appears in the special directory configuration context,
+      // add it to the enclosing server context instead. This way it will be
+      // possible to complement all server-enclosed contexts (including this
+      // special one) with the server scope options.
+      //
+      context* c (dir_context->special ? srv_context : dir_context);
+
+      if (dir_context->special)
+        //
+        // Make sure the special directory context is also in the option lists
+        // map. Later the context will be populated with an enclosing server
+        // context options.
+        //
+        srv.options_.emplace (dir_context, name_values ());
+
+      const char* name (parms->cmd->name);
+      if (strcmp (name, "SetHandler") == 0)
+      {
+        // Keep track of a request handling allowability.
+        //
+        srv.options_.emplace (c, name_values ()).first->first->handling =
+          value && *value == srv.name_
+          ? request_handling::allowed
+          : request_handling::disallowed;
+
+        return 0;
+      }
+
+      return srv.add_option (c, name, move (value));
+    }
+
+    const char* service::
+    add_option (context* ctx, const char* name, optional<string> value)
+    {
+      auto i (option_descriptions_.find (name));
+      assert (i != option_descriptions_.end ());
+
+      // Check that option value presense is expected.
+      //
+      if (i->second != static_cast<bool> (value))
+        return value ? "unexpected value" : "value expected";
+
+      options_[ctx].emplace_back (name + name_.length () + 1, move (value));
+      return 0;
+    }
+
+    void service::
+    complement (context* enclosed, context* enclosing)
+    {
+      auto i (options_.find (enclosing));
+
+      // The enclosing context may have no options. It can be the context of a
+      // server that has no configuration directives in it's immediate scope,
+      // but has ones in it's enclosed scope (directory or virtual server).
+      //
+      if (i != options_.end ())
+      {
+        const name_values& src (i->second);
+        name_values& dest (options_[enclosed]);
+        dest.insert (dest.begin (), src.begin (), src.end ());
+      }
+
+      if (enclosed->handling == request_handling::inherit)
+        enclosed->handling = enclosing->handling;
+    }
+
+    void service::
+    finalize_config (server_rec* s)
+    {
+      if (!version_logged_)
+      {
+        log l (s, this);
+        exemplar_.version (l);
+        version_logged_ = true;
+      }
+
+      // Complement directory configuration contexts with options of the
+      // enclosing server configuration context. By this time virtual server
+      // contexts are already complemented with the main server configuration
+      // context options as a result of the merge_server_context() calls.
+      //
+      for (const auto& o: options_)
+      {
+        // Is a directory configuration context.
+        //
+        if (o.first->server != nullptr)
+          complement (o.first, o.first->server);
+      }
+
+      options_parsed_ = true;
+    }
+
+    void service::
+    clear_config ()
+    {
+      options_.clear ();
+      options_parsed_ = false;
+    }
+  }
+}
-- 
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