add logger in web site description to be able to report error into log

David RENÉ
1 parent 102790d5
Showing 2 changed files with 164 additions and 141 deletions Show diff stats
web/CXM_making_a_web_site.anubis
web/CXM_multihost_http_server.anubis
@@ -554,8 +554,9 @@ define List(HTTP_header)
 define WEB_Session -> String    // the function constructed returns the name of the state
   make_save_session_function
   (
-    Int     timeout, 
-    String  state_directory
+    Int                       timeout,
+    String                    state_directory,
+    (LogLevel, String) -> One logger
   ) =
   (WEB_Session s_var) |->
     //Set the new timeout
@@ -567,10 +568,10 @@ define WEB_Session -&gt; String    // the function constructed returns the name of 
        session_name = s_var.session_id,
            //println("make_save_state_function " + state_directory+"/s"+state_name);
       if save(to_be_saved,state_directory+"/"+session_name) is ok then
-        println("----- session ["+session_name+"] saved"+dump_WEB_Session_Fields(*s_var.fields));
+        logger(logInfo, "----- session ["+session_name+"] saved"+dump_WEB_Session_Fields(*s_var.fields));
         session_name
       else 
-        println("Cannot create session file in '"+state_directory+"'.\n");
+        logger(logError, ("Cannot create session file in '"+state_directory+"'.\n"));
         ""
 .
@@ -621,7 +622,8 @@ define Previous_Session
 define (List(String) file_names) -> One
   make_delete_out_of_date_sessions_function
   (
-    String  state_directory
+    String  state_directory,
+    (LogLevel, String) -> One logger
   ) =
    (List(String) file_names) |-df->
    if file_names is 
@@ -644,7 +646,7 @@ define (List(String) file_names) -&gt; One
                   df(t)
          )
          else 
-          println("Can't retreive session "+h+", hence will be deleted");
+          logger(logError, "Can't retreive session "+h+", hence will be deleted");
           (forget(remove(file_path)); df(t))
      }. 
@@ -3064,19 +3066,23 @@ read CXM_web_arg_encode.anubis
 define ($State s) -> String    // the function constructed returns the name of the state
-   make_save_state_function
-     (
-       Int     timeout, 
-       String    state_directory
-     ) =
-   ($State s) |->
+  make_save_state_function
+  (
+    Int                       timeout,
+    String                    state_directory,
+    (LogLevel, String) -> One logger
+  )=
+  ($State s) |->
          with    time_stamp = now+timeout, 
                 to_be_saved = (time_stamp,s), 
                  state_name = to_ascii(sha1(s)), 
            //println("make_save_state_function " + state_directory+"/s"+state_name);
-           if save(to_be_saved,state_directory+"/s"+state_name) is ok 
-           then state_name
-           else (print("Cannot create state file in '"+state_directory+"'.\n"); "").
+           if save(to_be_saved,state_directory+"/s"+state_name) is ok then
+            state_name
+           else 
+            logger(logError, "Cannot create state file in '"+state_directory+"'.\n");
+            ""
+.
    When  a request  arrives, we  need to  retrieve the  previous state  from  the server's
@@ -3414,43 +3420,47 @@ define ($State          previous,
         HTTP_Info       http_info, 
         List(Web_arg)   lwa,
         Bool            is_https) -> $State
-   make_apply_action_function
-     (
-       List(Web_Action($State))   actions_list
-     ) = 
-   with f = 
-     ($State               previous, 
-      String                       action_name, 
-      HTTP_Info                    http_info, 
-      List(Web_arg)                lwa,
-      Bool                         is_https,
-      List(Web_Action($State))     actions) |-f-> 
+  make_apply_action_function
+  (
+    List(Web_Action($State))  actions_list,
+    (LogLevel, String) -> One logger                //logger    
+  )= 
+  with f = 
+     ($State                    previous, 
+      String                    action_name, 
+      HTTP_Info                 http_info, 
+      List(Web_arg)             lwa,
+      Bool                      is_https,
+      List(Web_Action($State))  actions) |-f-> 
         //println("Looking for action ["+action_name+"]");
         if actions is 
           {
-            [ ] then print("action '"+action_name+
-                              "' not found.\n"); previous,
-            [ac1 . others] then if ac1 is 
+            [ ]             then 
+              logger(logError, "action '"+action_name+"' not found.\n"); previous,
+            [ac1 . others]  then if ac1 is 
               {
-                http_action(an,allow,do_it) then 
-                  if an = action_name 
-                  then if is_https
-                       then (print("HTTP action '"+an+
-                                     "' called through HTTPS (denied).\n"); 
-                              previous)
-                       else if allow(previous) 
-                            then do_it(http_info,lwa,previous)
-                            else previous
-                  else f(previous,action_name,http_info,lwa,is_https,others),
-   
+                //check for http action
+                http_action(an, allow, do_it) then 
+                
+                  //Action name found
+                  if an = action_name then
+                    if is_https then
+                      (logger(logError, "HTTP action '"+an+"' called through HTTPS (denied).\n"); previous)
+                    else 
+                      if allow(previous) then
+                        do_it(http_info,lwa,previous)
+                      else 
+                        previous
+                  else 
+                    f(previous,action_name,http_info,lwa,is_https,others),
+                //check https action
                 https_action(an,allow,do_it) then
                   if an = action_name 
                   then if is_https
                        then if allow(previous)
                             then do_it(http_info,lwa,previous)
                             else previous
-                       else (print("HTTPS action '"+an+
-                                     "' called through HTTP (denied).\n"); 
+                       else (logger(logError, "HTTPS action '"+an+"' called through HTTP (denied).\n"); 
                              previous)
                   else f(previous,action_name,http_info,lwa,is_https,others),
@@ -3548,40 +3558,41 @@ define List(HTTP_header)
 public define Web_Site
-   make_web_site_description
-     (
-       String                      website_name,   // site_UID
-       List(String)                common_names,   // for example: ["www.our-business.com"]
-       String                      site_directory,     
-       String                      state_directory,     
-       One -> One         init, 
-       (HTTP_Info, 
-        List(Web_arg),
-        Bool is_https) -> $State   initial_state,
-       ($State expired,
-        Maybe(String),
-        HTTP_Info,
-        List(Web_arg),
-        Bool is_https) -> $State    ticket_expired_state, 
-       (Maybe(String),
-        HTTP_Info,
-        List(Web_arg),
-        Bool is_https) -> $State   ticket_lost_state, 
-       List(Web_Action($State))    actions, 
-       $State -> HTTP_Answer       compute_page,
-       $State -> List(HTTP_header) additional_headers,
-       List(HTTP_header)           constant_additional_headers, 
-       Int                         timeout,
-       Redirections                redirections, 
-       String                      charset, 
-       List(String)                journal_extensions,
-       List(String)                journal_headers, 
-       String                      secret, 
-       List(MIME)                  known_mime_types,
-       (String action_name,
-        List(Web_arg) args) -> One before_send_file
-     ) = 
-      init(unique); 
+  make_web_site_description
+  (
+    String                      website_name,   // site_UID
+    List(String)                common_names,   // for example: ["www.our-business.com"]
+    String                      site_directory,     
+    String                      state_directory,     
+    One -> One                  init, 
+    (HTTP_Info, 
+    List(Web_arg),
+    Bool is_https) -> $State   initial_state,
+    ($State expired,
+    Maybe(String),
+    HTTP_Info,
+    List(Web_arg),
+    Bool is_https) -> $State    ticket_expired_state, 
+    (Maybe(String),
+    HTTP_Info,
+    List(Web_arg),
+    Bool is_https) -> $State   ticket_lost_state, 
+    List(Web_Action($State))    actions, 
+    $State -> HTTP_Answer       compute_page,
+    $State -> List(HTTP_header) additional_headers,
+    List(HTTP_header)           constant_additional_headers, 
+    Int                         timeout,
+    Redirections                redirections, 
+    String                      charset, 
+    List(String)                journal_extensions,
+    List(String)                journal_headers,
+    (LogLevel, String) -> One   logger,                 //logger
+    String                      secret, 
+    List(MIME)                  known_mime_types,
+    (String action_name,
+    List(Web_arg) args) -> One before_send_file
+  )= 
+  init(unique);
       //
@@ -3594,10 +3605,10 @@ public define Web_Site
       //
       // construct tool functions
       // TODO 'make_separate_web_args_function' must retrieve state_cookies before parsing web_args if using_state_cookies is true
-   with save_state = make_save_state_function(timeout, state_directory),    
+   with save_state = make_save_state_function(timeout, state_directory, logger),    
     retrieve_state = make_retrieve_state_function(state_directory), 
  separate_web_args = make_separate_web_args_function(state_directory, retrieve_state, website_name), 
-      apply_action = make_apply_action_function(actions),
+      apply_action = make_apply_action_function(actions, logger),
       //
       // construct the site handler
       //
@@ -3670,6 +3681,7 @@ public define Web_Site
                                   charset, 
                                   journal_extensions, 
                                   journal_headers,
+                                  logger,
                                   secret,
                                   known_mime_types,
                                   site_handler(http_port, https_port),
@@ -3717,7 +3729,7 @@ define HTTP_Answer
       // content of page
       sequence([
-        preformated([size(14)], "Anubis Web Server - Calexium Lib v1.00 - Anubis language v1.14"),
+        preformated([size(14)],"Anubis Web Server - Standard Lib v1.14.0.0 - Anubis language v1.14"),
         preformated([size(12)],"Error "+to_String(http_status)),
         preformated([size(12)],"Internal message :"+message),
         br,
@@ -3816,38 +3828,40 @@ define Maybe(WEB_Controller)
   (
     String                controller_name,
     List(WEB_Controller)  controllers,
+    (LogLevel, String) -> One   logger                 //logger
   )=
   if controllers is
   {
     []      then
-      println("Can't find controller ["+controller_name+"]");
+      logger(logWarning, "Can't find controller ["+controller_name+"]");
       failure,
     [h . t] then
       if h.name = controller_name then
         //println("Controller ["+controller_name+"] found");
         success(h)
       else
-        get_controller(controller_name, t)
+        get_controller(controller_name, t, logger)
   }
 .
 define WEB_Page_Renderer
   get_page_renderer
   (
-    String                  renderer_name,
-    List(WEB_Page_Renderer) renderers,
+    String                    renderer_name,
+    List(WEB_Page_Renderer)   renderers,
+    (LogLevel, String) -> One logger                 //logger    
   )=
   if renderers is
   {
     []      then
-      println("Can't find page_renderer ["+renderer_name+"], use the default");
+      logger(logWarning, "Can't find page_renderer ["+renderer_name+"], use the default");
       default_page_renderer,
     [h . t] then
       if h.name = renderer_name then
         //println("Controller ["+controller_name+"] found");
         h
       else
-        get_page_renderer(renderer_name, t)
+        get_page_renderer(renderer_name, t, logger)
   }
 .
@@ -3857,18 +3871,19 @@ define WEB_Page_Renderer
     WEB_Session             _session,
     WEB_Page_Renderer       _current_page_renderer,
     List(WEB_Page_Renderer) renderers,
+    (LogLevel, String) -> One   logger                 //logger
   )=
   //get the renderer page name to use from the session "AWS_PAGE_RENDERER"
   if get_String(_session.fields, "AWS_PAGE_RENDERER") is
   {
-    failure                 then println("No renderer defined, use the default"); default_page_renderer,
+    failure                 then logger(logWarning, "No renderer defined, use the default"); default_page_renderer,
     success(renderer_name)  then
       //check if the renderer_page already in cache
       if renderer_name = _current_page_renderer.name then
         _current_page_renderer
       else
         //if not in cache, use the selector function
-        get_page_renderer(renderer_name, renderers)
+        get_page_renderer(renderer_name, renderers, logger)
   }
 .
@@ -3887,7 +3902,8 @@ define (Maybe(WEB_Session), HTTP_Answer)
     Maybe(String)         _mb_action_name,
     (HTTP_Info, 
      Var(List(Web_arg)),
-     Bool is_https) -> WEB_Session   initial_session,
+     Bool is_https) -> WEB_Session  initial_session,
+     (LogLevel, String) -> One      logger                 //logger
   )=
   //get the action name
   with mb_action_name = 
@@ -3902,47 +3918,47 @@ define (Maybe(WEB_Session), HTTP_Answer)
     failure               then 
       //(failure, error_page(http_not_found, "Action name failure", _session)),
       with new_session = initial_session(_session.web_request.http_info, _session.web_request.lwa, _session.web_request.is_https),
-      if get_controller(get_String(*new_session.web_request.lwa, "aws_controller", "root"), controllers) is
+      if get_controller(get_String(*new_session.web_request.lwa, "aws_controller", "root"), controllers, logger) is
       {
         failure                   then (failure, error_page(http_not_found, "Initial Session Controller not found", new_session)),
-        success(new_controller)   then apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, new_session, failure, initial_session),
+        success(new_controller)   then apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, new_session, failure, initial_session, logger),
       },      
     success(action_name)  then
-      println("ACTION_NAME ["+action_name+"]");
+      logger(logInfo, "ACTION_NAME ["+action_name+"]");
       if apply_action(_session, action_name, *controller.controller_actions) is
       {
         http_answer(session, answer)  then (success(session), answer),
         http_answer(answer)           then (success(_session), answer),
         redirect(new_session)         then
-          if get_controller(get_String(*new_session.web_request.lwa, "aws_controller", "root"), controllers) is
+          if get_controller(get_String(*new_session.web_request.lwa, "aws_controller", "root"), controllers, logger) is
           {
             failure                   then (failure, error_page(http_not_found, "Redirect Controller not found", new_session)),
-            success(new_controller)   then apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, new_session, failure, initial_session),
+            success(new_controller)   then apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, new_session, failure, initial_session, logger),
           },
         redirect(new_session, r_controller_name, r_action_name)         then
-          if get_controller(r_controller_name, controllers) is
+          if get_controller(r_controller_name, controllers, logger) is
           {
             failure                   then (failure, error_page(http_not_found, "Redirect Controller "+r_controller_name+" not found", new_session)),
             success(new_controller)   then
-              apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, new_session, success(r_action_name), initial_session),
+              apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, new_session, success(r_action_name), initial_session, logger),
           },
         redirect_to_previous             then
-          if get_controller(get_String(*_session.previous_web_request.lwa, "aws_controller", "root"), controllers) is
+          if get_controller(get_String(*_session.previous_web_request.lwa, "aws_controller", "root"), controllers, logger) is
           {
             failure                   then (failure, error_page(http_not_found, "Redirect to previous Controller not found", _session)),
             success(new_controller)   then 
               since _session is web_session(id, lang, entries, _, previous),
-              apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, web_session(id, lang, entries, previous, previous), failure, initial_session),
+              apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, web_session(id, lang, entries, previous, previous), failure, initial_session, logger),
           },
         redirect_to_previous(entries) then
-          if get_controller(get_String(*_session.previous_web_request.lwa, "aws_controller", "root"), controllers) is
+          if get_controller(get_String(*_session.previous_web_request.lwa, "aws_controller", "root"), controllers, logger) is
           {
             failure                   then (failure, error_page(http_not_found, "Redirect to previous Controller not found", _session)),
             success(new_controller)   then 
               since _session is web_session(id, lang, _, _, previous),
-              apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, web_session(id, lang, entries, previous, previous), failure, initial_session),
+              apply_controller_action(new_controller, controllers, _current_page_renderer, page_renderers, cinfo, web_session(id, lang, entries, previous, previous), failure, initial_session, logger),
           },          
         //ajax(answer)                              then (failure, answer),
         //ajax with modified session that must be saved
@@ -3955,7 +3971,7 @@ define (Maybe(WEB_Session), HTTP_Answer)
         send_file(file_path, c_disposition)       then  (failure,          send_file(file_path, c_disposition)),
         renderer_content(session, title, content) then  
           with the_session = if session is {failure then _session, success(__session) then __session},
-          with page_renderer = get_page_renderer(the_session, _current_page_renderer, page_renderers),
+          with page_renderer = get_page_renderer(the_session, _current_page_renderer, page_renderers, logger),
           (session, page_renderer.page_layout(the_session, title, content))
       }
   }
@@ -3986,7 +4002,8 @@ public define Web_Site
     Redirections                            redirections, 
        String                      charset, 
        List(String)                journal_extensions,
-       List(String)                journal_headers, 
+       List(String)                journal_headers,
+    (LogLevel, String) -> One     logger,                 //logger
        String                      secret, 
        List(MIME)                  known_mime_types,
        (String action_name,
@@ -4007,7 +4024,7 @@ public define Web_Site
       //
       // construct tool functions
       // TODO 'make_separate_web_args_function' must retrieve state_cookies before parsing web_args if using_state_cookies is true
-   with save_session = make_save_session_function(timeout, state_directory),
+   with save_session = make_save_session_function(timeout, state_directory, logger),
    with current_page_renderer = var((WEB_Page_Renderer)default_page_renderer),
  //   retrieve_session = make_retrieve_session_function(state_directory, website_name), 
  //separate_web_args = make_separate_web_args_function(state_directory, retrieve_state), 
@@ -4022,20 +4039,20 @@ public define Web_Site
                        List(Web_arg)   _lwa,
                        Bool                 is_https) |-> 
         //(Printable_tree)
-      //println("host_name "+host_name);
-      //println(dump_http_info(http_info));
-      println(dump_web_arg_values(_lwa));
+      logger(logTrace,"host_name "+host_name);
+      logger(logTrace,dump_http_info(http_info));
+      logger(logTrace, dump_web_arg_values(_lwa));
       with cinfo = info(host_name, http_port, https_port, site_directory, secret),
     //retrieve the previous session and determine the new one
     with current_session = if retrieve_session(http_info, state_directory, website_name) is
     {
         not_found                     then
-          println("previous state not found");
+          logger(logInfo, "previous state not found");
           initial_session(http_info, var(_lwa), is_https), 
         out_of_date(previous_session) then 
-          println("previous out_of_date");
+          logger(logInfo, "previous out_of_date");
           //expired_session(previous_session, http_info, var(_lwa), is_https), 
           since previous_session is web_session(id, lang, entries, previous, _),
           web_session(id, lang, entries, web_request(http_info, var(_lwa), is_https), previous)
@@ -4048,13 +4065,13 @@ public define Web_Site
     //apply the action according to current session
     //since apply_controller_action(get_controller(get_String(lwa, "aws_controller", "root"), *web_controllers), *web_controllers, current_session)
-    since if get_controller(get_String(*current_session.web_request.lwa, "aws_controller", "root"), *web_controllers) is
+    since if get_controller(get_String(*current_session.web_request.lwa, "aws_controller", "root"), *web_controllers, logger) is
       {
         failure                   then           
           (failure, error_page(http_not_found, "Controller not found", current_session)),
         success(new_controller)   then 
-          apply_controller_action(new_controller, *web_controllers, *current_page_renderer, *web_page_renderers, cinfo, current_session, failure, initial_session),
+          apply_controller_action(new_controller, *web_controllers, *current_page_renderer, *web_page_renderers, cinfo, current_session, failure, initial_session, logger),
       }
       is (mb_new_session, http_answer),
@@ -4080,7 +4097,7 @@ public define Web_Site
        // make the delete_out_of_date function
        //
        delete_out_of_date = 
-         make_delete_out_of_date_sessions_function(site_directory+"/states"), 
+         make_delete_out_of_date_sessions_function(site_directory+"/states", logger), 
        //
        // construct the web site description
        //
@@ -4091,6 +4108,7 @@ public define Web_Site
                                   charset, 
                                   journal_extensions, 
                                   journal_headers,
+                                  logger,
                                   secret,
                                   known_mime_types,
                                   site_handler(http_port,https_port),
@@ -4111,22 +4129,23 @@ public define Web_Site
 define String
   get_site_uid
   (
-    String site_path
+    String site_path,
+    (LogLevel, String) -> One   logger                 //logger
   )=
   with file_name = site_path+"/site_UID",
     if read_from_file(file_name)  is
     {
       cannot_find_file then
-        println("site UID doesn't exists. Generating it now");
+        logger(logInfo,"site UID doesn't exists. Generating one now");
         with uid = generate_random_string(9),
         if write_to_file(file_name, to_byte_array(uid)) is
         {
-          cannot_open_file  then println("Can't create site UID here "+file_name);"",
-          write_error(_)    then println("Can't write site UID here "+file_name);"",
+          cannot_open_file  then logger(logError, "Can't create site UID here "+file_name);"",
+          write_error(_)    then logger(logError, "Can't write site UID here "+file_name);"",
           ok                then uid
         }
       read_error(_)   then  
-        println("cannot read site UID from "+file_name);""
+        logger(logError, "cannot read site UID from "+file_name);""
       ok(ba)          then  to_string(ba)
    }
   .
@@ -4159,7 +4178,8 @@ public define Web_Site
        Redirections                redirections, 
        String                      charset, 
        List(String)                journal_extensions,
-       List(String)                journal_headers, 
+       List(String)                journal_headers,
+    (LogLevel, String) -> One                          logger,                 //logger
        String                      secret, 
        List(MIME)                  known_mime_types,
        (String action_name,
@@ -4168,8 +4188,8 @@ public define Web_Site
   )
   =
     //generate an unique ID if doesn't exist in root of site_directory
-    with site_UID = get_site_uid(site_directory),
-    make_web_site_description(site_UID, common_names, site_directory, state_directory, init, initial_state, ticket_expired_state, ticket_lost_state, actions, compute_page, additional_headers, constant_additional_headers, timeout, redirections, charset, journal_extensions, journal_headers, secret, known_mime_types, before_send_file)
+    with site_UID = get_site_uid(site_directory, logger),
+    make_web_site_description(site_UID, common_names, site_directory, state_directory, init, initial_state, ticket_expired_state, ticket_lost_state, actions, compute_page, additional_headers, constant_additional_headers, timeout, redirections, charset, journal_extensions, journal_headers, logger, secret, known_mime_types, before_send_file)
   .
@@ -4,6 +4,8 @@
  *Title*                        A Multi Host HTTP/HTTPS Server
  *Copyright*                 Copyright (c) Anubis Team 2003-2007.
+                             (c) Calexium 2007-2013
+                             (c) David René 2014-2019
  *Authors*  Alain Prouté
@@ -12,9 +14,9 @@
  *Revised*
-  June 2015 : Optimization of the file upload
-  July 2007 : Initial version in calexium_lib
-
+  June  2015 : Optimization of the file upload
+  July  2007 : Initial version in calexium_lib
+  March 2019 : move as standard lib 
  *Overviews*
    In this  file a HTTP/HTTPS server  is defined, which  is able to handle  multiple hosts
@@ -171,10 +173,9 @@ read system/string.anubis
 read system/files.anubis
 read system/lists.anubis
 read system/data_io.anubis
+read system/logger.anubis
 read web/mime.anubis
-
-
    *** (4) Site descriptions.
    The type HTTP_Info gathers informations comming along with the client's request.  These
@@ -227,6 +228,7 @@ public type Web_Site_Description:
      String                                             charset,
      List(String)                                       journal_extensions,
      List(String)                                       journal_headers,
+     (LogLevel, String) -> One                          logger,                 //logger
      String                                             authorization_secret,
      List(MIME)                                         known_mime_types,
      (String          host_name,
@@ -1282,11 +1284,11 @@ define One
      (
        if file(site_directory(desc)+"/journal/"+make_current_journal_file_name,append) is
          {
-           failure then unique,
-           success(journal_file) then
+           failure                then unique,
+           success(journal_file)  then
              forget(reliable_write(file(journal_file),ba_msg))
-         };
-       forget(reliable_write(file(stdout),ba_msg))
+         }
+       //forget(reliable_write(file(stdout),ba_msg))
      ).
@@ -3231,20 +3233,21 @@ define Maybe(String)
      }.
 define Maybe((String,Web_Site_Description))
-   get_site
-     (
-       String                       requested_host,
-       List(Web_Site_Description)   sites
-     ) =
-   if sites is
-     {
-       [ ] then print("Requested host '"+requested_host+"' does not exist.\n"); failure,
-       [site1 . others] then
-         if site1 is web_site_description(common_names,_,_,_,_,_,_,_,_,_,_) then
-         if member(common_names,requested_host)
-         then success((requested_host,site1))
-         else get_site(requested_host,others)
-     }.
+  get_site
+  (
+    String                       requested_host,
+    List(Web_Site_Description)   sites
+  )=
+  if sites is
+  {
+    [ ] then print("Requested host '"+requested_host+"' does not exist.\n"); failure,
+    [site1 . others] then
+      if site1 is web_site_description(common_names,_,_,_,_,_,_,_,_,_,_,_) then
+      if member(common_names,requested_host)
+      then success((requested_host,site1))
+      else get_site(requested_host,others)
+  }
+.
 define Maybe((String,Web_Site_Description))