first commit

.clang-format

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+# requires clang-format >= 3.6
+BasedOnStyle: "LLVM"
+IndentWidth: 2
+ColumnLimit: 120
+BreakBeforeBraces: Linux
+AllowShortFunctionsOnASingleLine: None

.gitignore

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+mod_vhost_maxclients.la
+mod_vhost_maxclients.lo
+mod_vhost_maxclients.o
+mod_vhost_maxclients.slo
+.libs

.travis.yml

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+language: c
+compiler:
+  - gcc
+  - clang
+before_install:
+  - sudo apt-get -qq update
+install:
+  - sudo apt-get -qq install rake bison libcurl4-openssl-dev libhiredis-dev libmarkdown2-dev libapr1-dev libaprutil1-dev apache2 libcap-dev
+env:
+  - HTTPD_VERSION=httpd-2.2.31
+    APR=apr-1.5.2 
+    APR_UTIL=apr-util-1.5.4 
+    HTTPD_TAR=${HTTPD_VERSION}.tar.gz 
+    APR_TAR=${APR}.tar.gz 
+    APR_UTIL_TAR=${APR_UTIL}.tar.gz 
+    HTTPD_CONFIG_OPT="--enable-module=all --enable-mods-shared=all"
+    APXS_CHECK_CMD="../${HTTPD_VERSION}/apache/bin/apachectl -v"
+  - HTTPD_VERSION=httpd-2.4.16 
+    APR=apr-1.5.2 
+    APR_UTIL=apr-util-1.5.4 
+    HTTPD_TAR=${HTTPD_VERSION}.tar.gz 
+    APR_TAR=${APR}.tar.gz 
+    APR_UTIL_TAR=${APR_UTIL}.tar.gz 
+    HTTPD_CONFIG_OPT=
+    APXS_CHECK_CMD="../${HTTPD_VERSION}/apache/bin/apachectl -v"
+before_script:
+  - cd ../
+  - wget http://ftp.jaist.ac.jp/pub/apache//httpd/${HTTPD_TAR}
+  - tar xf ${HTTPD_TAR}
+  - cd ${HTTPD_VERSION}/srclib
+  - wget http://ftp.jaist.ac.jp/pub/apache//apr/${APR_TAR}
+  - wget http://ftp.jaist.ac.jp/pub/apache//apr/${APR_UTIL_TAR}
+  - tar xf ${APR_TAR}
+  - tar xf ${APR_UTIL_TAR}
+  - ln -s ${APR} apr
+  - ln -s ${APR_UTIL} apr-util
+  - cd ..
+  - ./configure --prefix=`pwd`/apache --with-included-apr ${HTTPD_CONFIG_OPT}
+  - make
+  - make install
+  - cd ../mod_vhost_maxclients
+script:
+  - echo ${APXS_CHECK_CMD}
+  - ${APXS_CHECK_CMD}
+  - make APXS=../${HTTPD_VERSION}/apache/bin/apxs

Makefile

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+##
+##  Makefile -- Build procedure for sample mod_vhost_maxclients Apache module
+##	  MATSUMOTO, Ryosuke
+##
+
+# target module source
+TARGET=mod_vhost_maxclients.c
+
+#   the used tools
+APXS=apxs
+APACHECTL=apachectl -k
+
+#   additional user defines, includes and libraries
+DEF=
+INC=
+LIB=
+WC=-Wc,-std=c99
+
+#   the default target
+all: mod_vhost_maxclients.so
+
+#   compile the DSO file
+mod_vhost_maxclients.so: $(TARGET)
+	$(APXS) -c $(DEF) $(INC) $(LIB) $(WC) $(TARGET)
+
+#   install the DSO file into the Apache installation
+#   and activate it in the Apache configuration
+install: all
+	$(APXS) -i -a -n 'vhost_maxclients' .libs/mod_vhost_maxclients.so
+
+#   cleanup
+clean:
+	-rm -rf .libs *.o *.so *.lo *.la *.slo *.loT
+
+#   reload the module by installing and restarting Apache
+reload: install restart
+
+#   the general Apache start/restart/stop procedures
+start:
+	$(APACHECTL) start
+restart:
+	$(APACHECTL) restart
+stop:
+	$(APACHECTL) stop
+

README.md

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+# mod_vhost_maxclients
+
+MaxClients per vhost, no using shared memory and global lock. mod_vhost_maxclients use only scoreboad for simple implementation.
+
+# Quick Install
+- build
+
+```
+make
+```
+
+- mod_vhost_maxclients.conf
+
+```
+LoadModule vhost_maxclients_module modules/mod_vhost_maxclients.so
+# mod_vhost_maxclinets use scoreboard
+ExtendedStatus On
+```
+
+- vhost.conf
+
+```apache
+<VirtualHost *>
+    DocumentRoot /path/to/web
+    ServerName test001.example.jp
+
+    # MaxClients per vhost using mod_vhost_maxclients
+    VhostMaxClients 3
+    # Ignore extensions from VhostMaxClients
+    IgnoreVhostMaxClientsExt .html .js .css
+
+</VirtualHost>
+```
+
+- logggin
+```
+[Thu Aug 27 21:16:54.540685 2015] [vhost_maxclients:debug] [pid 23981] mod_vhost_maxclients.c(93): DEBUG: (increment test001.example.jp:80): 1/3
+[Thu Aug 27 21:16:54.540708 2015] [vhost_maxclients:debug] [pid 23981] mod_vhost_maxclients.c(93): DEBUG: (increment test001.example.jp:80): 2/3
+[Thu Aug 27 21:16:54.540713 2015] [vhost_maxclients:debug] [pid 23981] mod_vhost_maxclients.c(93): DEBUG: (increment test001.example.jp:80): 3/3
+[Thu Aug 27 21:16:54.540716 2015] [vhost_maxclients:debug] [pid 23981] mod_vhost_maxclients.c(93): DEBUG: (increment test001.example.jp:80): 4/3
+[Thu Aug 27 21:16:54.540726 2015] [vhost_maxclients:notice] [pid 23981] NOTICE: (return 503 from test001.example.jp:80): 4/3
+```

mod_vhost_maxclients.c

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+#include "httpd.h"
+#include "http_config.h"
+#include "http_request.h"
+#include "http_protocol.h"
+#include "http_core.h"
+#include "http_log.h"
+#include "ap_mpm.h"
+#include "apr_strings.h"
+
+#define MODULE_NAME "mod_vhost_maxclients"
+#define MODULE_VERSION "0.0.1"
+
+#if (AP_SERVER_MINORVERSION_NUMBER > 2)
+#define __APACHE24__
+#endif
+
+#ifdef __APACHE24__
+#define ap_get_scoreboard_worker ap_get_scoreboard_worker_from_indexes
+#endif
+
+#define _log_debug                                                                                                     \
+  ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, NULL, "DEBUG: " MODULE_NAME "/" MODULE_VERSION "%s:%d", __func__, __LINE__)
+
+#ifdef __APACHE24__
+#include "http_main.h"
+#else
+#define ap_server_conf NULL
+#endif
+
+#define VHOST_MAXEXTENSIONS 16
+
+#if !defined(__APACHE24__) && defined(_WIN32)
+/*
+ * libhttpd.dll does not export following variables.
+ * This won't work correctly, but working well for other functional.
+ */
+int ap_extended_status = 0;
+#endif
+
+module AP_MODULE_DECLARE_DATA vhost_maxclients_module;
+static int vhost_maxclients_server_limit, vhost_maxclients_thread_limit;
+
+typedef struct {
+
+  /* vhost max clinetns */
+  signed int vhost_maxclients;
+  apr_array_header_t *ignore_extensions;
+
+} vhost_maxclients_config;
+
+static void *vhost_maxclients_create_server_config(apr_pool_t *p, server_rec *s)
+{
+  vhost_maxclients_config *scfg = (vhost_maxclients_config *)apr_pcalloc(p, sizeof(*scfg));
+
+  scfg->vhost_maxclients = 0;
+  scfg->ignore_extensions = apr_array_make(p, VHOST_MAXEXTENSIONS, sizeof(char *));
+
+  return scfg;
+}
+
+static int check_extension(char *filename, apr_array_header_t *exts)
+{
+  int i;
+  for (i = 0; i < exts->nelts; i++) {
+    const char *extension = ((char **)exts->elts)[i];
+    ssize_t name_len = strlen(filename) - strlen(extension);
+    if (name_len >= 0 && strcmp(&filename[name_len], extension) == 0)
+      return 1;
+  }
+  return 0;
+}
+
+static char *build_vhostport_name(request_rec *r)
+{
+  ssize_t vhostport_len;
+  char *vhostport;
+
+  vhostport_len = strlen(r->hostname) + sizeof(":65536");
+  vhostport = apr_pcalloc(r->pool, vhostport_len);
+  apr_snprintf(vhostport, vhostport_len, "%s:%d", r->hostname, r->connection->local_addr->port);
+
+  return vhostport;
+}
+
+static int vhost_maxclients_handler(request_rec *r)
+{
+  int i, j;
+  int vhost_count = 0;
+  char *vhostport;
+  vhost_maxclients_config *scfg =
+      (vhost_maxclients_config *)ap_get_module_config(r->server->module_config, &vhost_maxclients_module);
+
+  if (!ap_is_initial_req(r)) {
+    return DECLINED;
+  }
+
+  if (scfg->vhost_maxclients <= 0) {
+    return DECLINED;
+  }
+
+  if (r->hostname == NULL) {
+    return DECLINED;
+  }
+
+  if (!ap_extended_status) {
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, "DEBUG: only used when ExtendedStatus On");
+    return DECLINED;
+  }
+
+  /* check ignore extesions */
+  if (check_extension(r->filename, scfg->ignore_extensions)) {
+    return DECLINED;
+  }
+
+  /* build vhostport name */
+  vhostport = build_vhostport_name(r);
+
+  for (i = 0; i < vhost_maxclients_server_limit; ++i) {
+    for (j = 0; j < vhost_maxclients_thread_limit; ++j) {
+      worker_score *ws_record = ap_get_scoreboard_worker(i, j);
+
+      switch (ws_record->status) {
+      case SERVER_BUSY_READ:
+      case SERVER_BUSY_WRITE:
+      case SERVER_BUSY_KEEPALIVE:
+      case SERVER_BUSY_LOG:
+      case SERVER_BUSY_DNS:
+      case SERVER_CLOSING:
+      case SERVER_GRACEFUL:
+        if (strcmp(vhostport, ws_record->vhost) == 0) {
+          vhost_count++;
+          ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, "DEBUG: (increment %s): %d/%d", vhostport,
+                       vhost_count, scfg->vhost_maxclients);
+          if (vhost_count > scfg->vhost_maxclients) {
+            ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf, "NOTICE: (return 503 from %s): %d/%d", vhostport,
+                         vhost_count, scfg->vhost_maxclients);
+            return HTTP_SERVICE_UNAVAILABLE;
+          }
+          break;
+        }
+      default:
+        break;
+      }
+    }
+  }
+
+  /* not reached vhost_maxclients */
+  return DECLINED;
+}
+
+static const char *set_vhost_maxclientsvhost(cmd_parms *parms, void *mconfig, const char *arg1)
+{
+  vhost_maxclients_config *scfg =
+      (vhost_maxclients_config *)ap_get_module_config(parms->server->module_config, &vhost_maxclients_module);
+  signed long int limit = strtol(arg1, (char **)NULL, 10);
+
+  if ((limit > 65535) || (limit < 0)) {
+    return "Integer overflow or invalid number";
+  }
+
+  scfg->vhost_maxclients = limit;
+
+  return NULL;
+}
+
+static const char *set_vhost_ignore_extensions(cmd_parms *parms, void *mconfig, const char *arg)
+{
+  vhost_maxclients_config *scfg =
+      (vhost_maxclients_config *)ap_get_module_config(parms->server->module_config, &vhost_maxclients_module);
+
+  if (VHOST_MAXEXTENSIONS < scfg->ignore_extensions->nelts) {
+    return "the number of ignore extensions exceeded";
+  }
+
+  *(const char **)apr_array_push(scfg->ignore_extensions) = arg;
+
+  return NULL;
+}
+
+static command_rec vhost_maxclients_cmds[] = {
+    AP_INIT_TAKE1("VhostMaxClients", set_vhost_maxclientsvhost, NULL, RSRC_CONF | ACCESS_CONF,
+                  "maximum connections per Vhost"),
+    AP_INIT_ITERATE("IgnoreVhostMaxClientsExt", set_vhost_ignore_extensions, NULL, ACCESS_CONF | RSRC_CONF,
+                    "Set Ignore Extensions."),
+    {NULL},
+};
+
+static int vhost_maxclients_init(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s)
+{
+  ap_mpm_query(AP_MPMQ_HARD_LIMIT_THREADS, &vhost_maxclients_thread_limit);
+  ap_mpm_query(AP_MPMQ_HARD_LIMIT_DAEMONS, &vhost_maxclients_server_limit);
+  ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
+               MODULE_NAME "/" MODULE_VERSION " enabled: %d/%d thread_limit/server_limit",
+               vhost_maxclients_thread_limit, vhost_maxclients_server_limit);
+
+  return OK;
+}
+
+static void vhost_maxclients_register_hooks(apr_pool_t *p)
+{
+  ap_hook_post_config(vhost_maxclients_init, NULL, NULL, APR_HOOK_MIDDLE);
+  ap_hook_access_checker(vhost_maxclients_handler, NULL, NULL, APR_HOOK_MIDDLE);
+}
+
+#ifdef __APACHE24__
+AP_DECLARE_MODULE(vhost_maxclients) = {
+#else
+module AP_MODULE_DECLARE_DATA vhost_maxclients_module = {
+#endif
+    STANDARD20_MODULE_STUFF, NULL,         /* create per-dir config structures     */
+    NULL,                                  /* merge  per-dir    config structures  */
+    vhost_maxclients_create_server_config, /* create per-server config
+                                              structures  */
+    NULL,                                  /* merge  per-server config structures  */
+    vhost_maxclients_cmds,                 /* table of config file commands        */
+    vhost_maxclients_register_hooks};