new file mode 100644
--- /dev/null
+++ b/src/http/modules/ngx_http_browser_module.c
@@ -0,0 +1,706 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+
+
+/*
+ * The module can check browser versions conforming to the following formats:
+ * X, X.X, X.X.X, and X.X.X.X.  The maximum values of each format may be
+ * 4000, 4000.99, 4000.99.99, and 4000.99.99.99.
+ */
+
+
+#define  NGX_HTTP_MODERN_BROWSER   0
+#define  NGX_HTTP_ANCIENT_BROWSER  1
+
+
+typedef struct {
+    u_char                      browser[12];
+    size_t                      skip;
+    size_t                      add;
+    u_char                      name[12];
+} ngx_http_modern_browser_mask_t;
+
+
+typedef struct {
+    ngx_uint_t                  version;
+    size_t                      skip;
+    size_t                      add;
+    u_char                      name[12];
+} ngx_http_modern_browser_t;
+
+
+typedef struct {
+    ngx_str_t                   name;
+    ngx_http_get_variable_pt    handler;
+    uintptr_t                   data;
+} ngx_http_browser_variable_t;
+
+
+typedef struct {
+    ngx_array_t                *modern_browsers;
+    ngx_array_t                *ancient_browsers;
+    ngx_http_variable_value_t  *modern_browser_value;
+    ngx_http_variable_value_t  *ancient_browser_value;
+
+    unsigned                    modern_unlisted_browsers:1;
+    unsigned                    netscape4:1;
+} ngx_http_browser_conf_t;
+
+
+static ngx_int_t ngx_http_msie_variable(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data);
+static ngx_int_t ngx_http_browser_variable(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data);
+
+static ngx_uint_t ngx_http_browser(ngx_http_request_t *r,
+    ngx_http_browser_conf_t *cf);
+ 
+static ngx_int_t ngx_http_browser_add_variable(ngx_conf_t *cf);
+static void *ngx_http_browser_create_conf(ngx_conf_t *cf);
+static char *ngx_http_browser_merge_conf(ngx_conf_t *cf, void *parent,
+    void *child);
+static int ngx_libc_cdecl ngx_http_modern_browser_sort(const void *one,
+    const void *two);
+static char *ngx_http_modern_browser(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
+static char *ngx_http_ancient_browser(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
+static char *ngx_http_modern_browser_value(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
+static char *ngx_http_ancient_browser_value(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
+
+
+static ngx_command_t  ngx_http_browser_commands[] = {
+
+    { ngx_string("modern_browser"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE12,
+      ngx_http_modern_browser,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
+    { ngx_string("ancient_browser"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
+      ngx_http_ancient_browser,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
+    { ngx_string("modern_browser_value"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_http_modern_browser_value,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
+    { ngx_string("ancient_browser_value"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_http_ancient_browser_value,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
+      ngx_null_command
+};
+
+
+static ngx_http_module_t  ngx_http_browser_module_ctx = {
+    ngx_http_browser_add_variable,         /* preconfiguration */
+    NULL,                                  /* postconfiguration */
+
+    NULL,                                  /* create main configuration */
+    NULL,                                  /* init main configuration */
+
+    NULL,                                  /* create server configuration */
+    NULL,                                  /* merge server configuration */
+
+    ngx_http_browser_create_conf,          /* create location configuration */
+    ngx_http_browser_merge_conf            /* merge location configuration */
+};
+
+
+ngx_module_t  ngx_http_browser_module = {
+    NGX_MODULE_V1,
+    &ngx_http_browser_module_ctx,          /* module context */
+    ngx_http_browser_commands,             /* module directives */
+    NGX_HTTP_MODULE,                       /* module type */
+    NULL,                                  /* init master */
+    NULL,                                  /* init module */
+    NULL,                                  /* init process */
+    NULL,                                  /* init thread */
+    NULL,                                  /* exit thread */
+    NULL,                                  /* exit process */
+    NULL,                                  /* exit master */
+    NGX_MODULE_V1_PADDING
+};
+
+
+static ngx_http_modern_browser_mask_t  ngx_http_modern_browser_masks[] = {
+
+    /* Opera must be the first browser to check */
+
+    /*
+     * "Opera/7.50 (X11; FreeBSD i386; U)  [en]"
+     * "Mozilla/5.0 (X11; FreeBSD i386; U) Opera 7.50  [en]"
+     * "Mozilla/4.0 (compatible; MSIE 6.0; X11; FreeBSD i386) Opera 7.50  [en]"
+     * "Opera/8.0 (Windows NT 5.1; U; ru)"
+     * "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; en) Opera 8.0"
+     * "Opera/9.01 (X11; FreeBSD 6 i386; U; en)"
+     */
+
+    { "opera",
+      0,
+      sizeof("Opera ") - 1,
+      "Opera"},
+
+    /* "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)" */
+
+    { "msie",
+      sizeof("Mozilla/4.0 (compatible; ") - 1,
+      sizeof("MSIE ") - 1,
+      "MSIE "},
+
+    /*
+     * "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.0) Gecko/20020610"
+     * "Mozilla/5.0 (Windows; U; Windows NT 5.1; ru-RU; rv:1.5) Gecko/20031006"
+     * "Mozilla/5.0 (Windows; U; Windows NT 5.1; ru-RU; rv:1.6) Gecko/20040206
+     *              Firefox/0.8"
+     * "Mozilla/5.0 (Windows; U; Windows NT 5.1; ru-RU; rv:1.7.8)
+     *              Gecko/20050511 Firefox/1.0.4"
+     * "Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.0.5) Gecko/20060729
+     *              Firefox/1.5.0.5"
+     */
+
+    { "gecko",
+      sizeof("Mozilla/5.0 (") - 1,
+      sizeof("rv:") - 1,
+      "rv:"},
+
+    /*
+     * "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; ru-ru) AppleWebKit/125.2
+     *              (KHTML, like Gecko) Safari/125.7"
+     * "Mozilla/5.0 (SymbianOS/9.1; U; en-us) AppleWebKit/413
+     *              (KHTML, like Gecko) Safari/413"
+     * "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en) AppleWebKit/418
+     *              (KHTML, like Gecko) Safari/417.9.3"
+     * "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; ru-ru) AppleWebKit/418.8
+     *              (KHTML, like Gecko) Safari/419.3"
+     */
+
+    { "safari",
+      sizeof("Mozilla/5.0 (") - 1,
+      sizeof("Safari/") - 1,
+      "Safari/"},
+
+    /*
+     * "Mozilla/5.0 (compatible; Konqueror/3.1; Linux)"
+     * "Mozilla/5.0 (compatible; Konqueror/3.4; Linux) KHTML/3.4.2 (like Gecko)"
+     * "Mozilla/5.0 (compatible; Konqueror/3.5; FreeBSD) KHTML/3.5.1
+     *              (like Gecko)"
+     */
+
+    { "konqueror",
+      sizeof("Mozilla/5.0 (compatible; ") - 1,
+      sizeof("Konqueror/") - 1,
+      "Konqueror/"},
+
+    { "", 0, 0, "" }
+
+};
+
+
+static ngx_http_browser_variable_t  ngx_http_browsers[] = {
+    { ngx_string("msie"), ngx_http_msie_variable, 0 },
+    { ngx_string("modern_browser"), ngx_http_browser_variable,
+          NGX_HTTP_MODERN_BROWSER },
+    { ngx_string("ancient_browser"), ngx_http_browser_variable,
+          NGX_HTTP_ANCIENT_BROWSER },
+    { ngx_null_string, NULL, 0 }
+};
+
+
+static ngx_int_t
+ngx_http_browser_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v,
+    uintptr_t data)
+{
+    ngx_uint_t                rc;
+    ngx_http_browser_conf_t  *cf;
+
+    cf = ngx_http_get_module_loc_conf(r, ngx_http_browser_module);
+
+    rc = ngx_http_browser(r, cf);
+
+    if (data == NGX_HTTP_MODERN_BROWSER && rc == NGX_HTTP_MODERN_BROWSER) {
+        *v = *cf->modern_browser_value;
+        return NGX_OK;
+    }
+
+    if (data == NGX_HTTP_ANCIENT_BROWSER && rc == NGX_HTTP_ANCIENT_BROWSER) {
+        *v = *cf->ancient_browser_value;
+        return NGX_OK;
+    }
+
+    *v = ngx_http_variable_null_value;
+    return NGX_OK;
+}
+
+
+static ngx_uint_t
+ngx_http_browser(ngx_http_request_t *r, ngx_http_browser_conf_t *cf)
+{
+    size_t                      len;
+    u_char                     *name, *ua, *last, c;
+    ngx_str_t                  *ancient;
+    ngx_uint_t                  i, version, ver, scale;
+    ngx_http_modern_browser_t  *modern;
+
+    if (r->headers_in.user_agent == NULL) {
+        if (cf->modern_unlisted_browsers) {
+            return NGX_HTTP_MODERN_BROWSER;
+        }
+
+        return NGX_HTTP_ANCIENT_BROWSER;
+    }
+
+    ua = r->headers_in.user_agent->value.data;
+    len = r->headers_in.user_agent->value.len;
+    last = ua + len;
+
+    if (cf->modern_browsers) {
+        modern = cf->modern_browsers->elts;
+
+        for (i = 0; i < cf->modern_browsers->nelts; i++) {
+            name = ua + modern[i].skip;
+
+            if (name >= last) {
+                continue;
+            }
+
+            name = (u_char *) ngx_strstr(name, modern[i].name);
+
+            if (name == NULL) {
+                continue;
+            }
+
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "browser: \"%s\"", name);
+
+            name += modern[i].add;
+
+            if (name >= last) {
+                continue;
+            }
+
+            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "version: \"%ui\" \"%s\"", modern[i].version, name);
+
+            version = 0;
+            ver = 0;
+            scale = 1000000;
+
+            while (name < last) {
+
+                c = *name++;
+
+                if (c >= '0' && c <= '9') {
+                    ver = ver * 10 + (c - '0');
+                    continue;
+                }
+
+                if (c == '.') {
+                    version += ver * scale;
+
+                    if (version > modern[i].version) {
+                        return NGX_HTTP_MODERN_BROWSER;
+                    }
+
+                    ver = 0;
+                    scale /= 100;
+                    continue;
+                }
+
+                break;
+            }
+
+            version += ver * scale;
+
+            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                           "version: \"%ui\" \"%ui\"",
+                           modern[i].version, version);
+
+            if (version >= modern[i].version) {
+                return NGX_HTTP_MODERN_BROWSER;
+            }
+        }
+
+        if (!cf->modern_unlisted_browsers) {
+            return NGX_HTTP_ANCIENT_BROWSER;
+        }
+    }
+
+    if (cf->netscape4) {
+        if (len > sizeof("Mozilla/4.72 ") - 1
+            && ngx_strncmp(ua, "Mozilla/", sizeof("Mozilla/") - 1) == 0
+            && ua[8] > '0' && ua[8] < '5')
+        {
+            return NGX_HTTP_ANCIENT_BROWSER;
+        }
+    }
+
+    if (cf->ancient_browsers) {
+        ancient = cf->ancient_browsers->elts;
+
+        for (i = 0; i < cf->ancient_browsers->nelts; i++) {
+            if (len >= ancient[i].len
+                && ngx_strstr(ua, ancient[i].data) != NULL)
+            {
+                return NGX_HTTP_ANCIENT_BROWSER;
+            }
+        }
+    }
+
+    if (cf->modern_unlisted_browsers) {
+        return NGX_HTTP_MODERN_BROWSER;
+    }
+
+    return NGX_HTTP_ANCIENT_BROWSER;
+}
+
+
+static ngx_int_t
+ngx_http_msie_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v,
+    uintptr_t data)
+{
+    if (r->headers_in.msie) {
+        *v = ngx_http_variable_true_value;
+        return NGX_OK;
+    }
+
+    *v = ngx_http_variable_null_value;
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_browser_add_variable(ngx_conf_t *cf)
+{
+    ngx_http_browser_variable_t   *var;
+    ngx_http_variable_t           *v;
+
+    for (var = ngx_http_browsers; var->name.len; var++) {
+
+        v = ngx_http_add_variable(cf, &var->name, NGX_HTTP_VAR_CHANGABLE);
+        if (v == NULL) {
+            return NGX_ERROR;
+        }
+
+        v->get_handler = var->handler;
+        v->data = var->data;
+    }
+
+    return NGX_OK;
+}
+
+
+static void *
+ngx_http_browser_create_conf(ngx_conf_t *cf)
+{
+    ngx_http_browser_conf_t  *conf;
+
+    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_browser_conf_t));
+    if (conf == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    /*
+     * set by ngx_pcalloc():
+     *
+     *     conf->modern_browsers = NULL;
+     *     conf->ancient_browsers = NULL;
+     *     conf->modern_browser_value = NULL;
+     *     conf->ancient_browser_value = NULL;
+     *
+     *     conf->modern_unlisted_browsers = 0;
+     *     conf->netscape4 = 0;
+     */
+
+    return conf;
+}
+
+
+static char *
+ngx_http_browser_merge_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+    ngx_http_browser_conf_t *prev = parent;
+    ngx_http_browser_conf_t *conf = child;
+
+    ngx_uint_t                  i, n;
+    ngx_http_modern_browser_t  *browsers, *opera;
+
+    /*
+     * At the merge the skip field is used to store the browser slot,
+     * it will be used in sorting and then will overwritten
+     * with a real skip value.  The zero value means Opera.
+     */
+
+    if (conf->modern_browsers == NULL) {
+        conf->modern_browsers = prev->modern_browsers;
+
+    } else {
+        browsers = conf->modern_browsers->elts;
+
+        for (i = 0; i < conf->modern_browsers->nelts; i++) {
+            if (browsers[i].skip == 0) {
+                goto found;
+            }
+        }
+
+        /*
+         * Opera may contain MSIE string, so if Opera was not enumerated
+         * as modern browsers, then add it and set a unreachable version
+         */
+
+        opera = ngx_array_push(conf->modern_browsers);
+        if (opera == NULL) {
+            return NGX_CONF_ERROR;
+        }
+
+        opera->skip = 0;
+        opera->version = 4001000000U;
+
+        browsers = conf->modern_browsers->elts;
+
+found:
+
+        ngx_qsort(browsers, (size_t) conf->modern_browsers->nelts,
+                  sizeof(ngx_http_modern_browser_t),
+                  ngx_http_modern_browser_sort);
+
+        for (i = 0; i < conf->modern_browsers->nelts; i++) {
+             n = browsers[i].skip;
+
+             browsers[i].skip = ngx_http_modern_browser_masks[n].skip;
+             browsers[i].add = ngx_http_modern_browser_masks[n].add;
+             (void) ngx_cpystrn(browsers[i].name,
+                                ngx_http_modern_browser_masks[n].name, 12);
+        }
+    }
+
+    if (conf->ancient_browsers == NULL) {
+        conf->ancient_browsers = prev->ancient_browsers;
+    }
+
+    if (conf->modern_browser_value == NULL) {
+        conf->modern_browser_value = prev->modern_browser_value;
+    }
+
+    if (conf->modern_browser_value == NULL) {
+        conf->modern_browser_value = &ngx_http_variable_true_value;
+    }
+
+    if (conf->ancient_browser_value == NULL) {
+        conf->ancient_browser_value = prev->ancient_browser_value;
+    }
+
+    if (conf->ancient_browser_value == NULL) {
+        conf->ancient_browser_value = &ngx_http_variable_true_value;
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+static int ngx_libc_cdecl
+ngx_http_modern_browser_sort(const void *one, const void *two)
+{
+    ngx_http_modern_browser_t *first = (ngx_http_modern_browser_t *) one;
+    ngx_http_modern_browser_t *second = (ngx_http_modern_browser_t *) two;
+
+    return (first->skip - second->skip);
+}
+
+
+static char *
+ngx_http_modern_browser(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_browser_conf_t *bcf = conf;
+
+    u_char                           c;
+    ngx_str_t                       *value;
+    ngx_uint_t                       i, n, version, ver, scale;
+    ngx_http_modern_browser_t       *browser;
+    ngx_http_modern_browser_mask_t  *mask;
+
+    value = cf->args->elts;
+
+    if (cf->args->nelts == 2) {
+        if (ngx_strcmp(value[1].data, "unlisted") == 0) {
+            bcf->modern_unlisted_browsers = 1;
+            return NGX_CONF_OK;
+        }
+
+        return NGX_CONF_ERROR;
+    }
+
+    if (bcf->modern_browsers == NULL) {
+        bcf->modern_browsers = ngx_array_create(cf->pool, 5,
+                                            sizeof(ngx_http_modern_browser_t));
+        if (bcf->modern_browsers == NULL) {
+            return NGX_CONF_ERROR;
+        }
+    }
+
+    browser = ngx_array_push(bcf->modern_browsers);
+    if (browser == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    mask = ngx_http_modern_browser_masks;
+
+    for (n = 0; mask[n].browser[0] != '\0'; n++) {
+        if (ngx_strcasecmp(mask[n].browser, value[1].data) == 0) {
+            goto found;
+        }
+    }
+
+    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                       "unknown browser name \"%V\"", &value[1]);
+
+    return NGX_CONF_ERROR;
+
+found:
+
+    /*
+     * at this stage the skip field is used to store the browser slot,
+     * it will be used in sorting in merge stage and then will overwritten
+     * with a real value
+     */
+
+    browser->skip = n;
+
+    version = 0;
+    ver = 0;
+    scale = 1000000;
+
+    for (i = 0; i < value[2].len; i++) {
+
+        c = value[2].data[i];
+
+        if (c >= '0' && c <= '9') {
+            ver = ver * 10 + (c - '0');
+            continue;
+        }
+
+        if (c == '.') {
+            version += ver * scale;
+            ver = 0;
+            scale /= 100;
+            continue;
+        }
+
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "invalid browser version \"%V\"", &value[2]);
+
+        return NGX_CONF_ERROR;
+    }
+
+    version += ver * scale;
+
+    browser->version = version;
+
+    return NGX_CONF_OK;
+}
+
+
+static char *
+ngx_http_ancient_browser(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_browser_conf_t *bcf = conf;
+
+    ngx_str_t   *value, *browser;
+    ngx_uint_t   i;
+
+    value = cf->args->elts;
+
+    for (i = 1; i < cf->args->nelts; i++) {
+        if (ngx_strcmp(value[i].data, "netscape4") == 0) {
+            bcf->netscape4 = 1;
+            continue;
+        }
+
+        if (bcf->ancient_browsers == NULL) {
+            bcf->ancient_browsers = ngx_array_create(cf->pool, 4,
+                                                     sizeof(ngx_str_t));
+            if (bcf->ancient_browsers == NULL) {
+                return NGX_CONF_ERROR;
+            }
+        }
+
+        browser = ngx_array_push(bcf->ancient_browsers);
+        if (browser == NULL) {
+            return NGX_CONF_ERROR;
+        }
+
+        *browser = value[i];
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+static char *
+ngx_http_modern_browser_value(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_browser_conf_t *bcf = conf;
+
+    ngx_str_t  *value;
+
+    bcf->modern_browser_value = ngx_palloc(cf->pool,
+                                           sizeof(ngx_http_variable_value_t));
+    if (bcf->modern_browser_value == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    value = cf->args->elts;
+
+    bcf->modern_browser_value->len = value[1].len;
+    bcf->modern_browser_value->valid = 1;
+    bcf->modern_browser_value->no_cachable = 0;
+    bcf->modern_browser_value->not_found = 0;
+    bcf->modern_browser_value->data = value[1].data;
+
+    return NGX_CONF_OK;
+}
+
+
+static char *
+ngx_http_ancient_browser_value(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_browser_conf_t *bcf = conf;
+
+    ngx_str_t  *value;
+
+    bcf->ancient_browser_value = ngx_palloc(cf->pool,
+                                            sizeof(ngx_http_variable_value_t));
+    if (bcf->ancient_browser_value == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    value = cf->args->elts;
+
+    bcf->ancient_browser_value->len = value[1].len;
+    bcf->ancient_browser_value->valid = 1;
+    bcf->ancient_browser_value->no_cachable = 0;
+    bcf->ancient_browser_value->not_found = 0;
+    bcf->ancient_browser_value->data = value[1].data;
+
+    return NGX_CONF_OK;
+}