Var: dynamic variables support.

This commit adds the variables $arg_NAME, $header_NAME, and $cookie_NAME.

13 files changed, 407 insertions, 49 deletions

diff --git a/docs/changes.xml b/docs/changes.xml
index 12ad11f8..13a66672 100644
--- a/docs/changes.xml
+++ b/docs/changes.xml
@@ -37,6 +37,12 @@ forwarded header to replace client address and protocol.
 </para>
 </change>
 
+<change type="feature">
+<para>
+ability to get dynamic variables.
+</para>
+</change>
+
 <change type="bugfix">
 <para>
 an index file that didn't contain a file extension was incorrectly
diff --git a/src/nxt_conf.h b/src/nxt_conf.h
index 46effac4..f95b61c1 100644
--- a/src/nxt_conf.h
+++ b/src/nxt_conf.h
@@ -72,6 +72,7 @@ typedef struct {
     nxt_mp_t             *pool;
     nxt_str_t            error;
     void                 *ctx;
+    nxt_array_t          *var_fields;  /* of nxt_var_field_t */
     nxt_mp_t             *conf_pool;
     nxt_uint_t           ver;
 } nxt_conf_validation_t;
diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index a5958788..47164e92 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -1210,6 +1210,11 @@ nxt_conf_validate(nxt_conf_validation_t *vldt)
 {
     nxt_int_t  ret;
 
+    vldt->var_fields = nxt_array_create(vldt->pool, 4, sizeof(nxt_var_field_t));
+    if (nxt_slow_path(vldt->var_fields == NULL)) {
+        return NXT_ERROR;
+    }
+
     ret = nxt_conf_vldt_type(vldt, NULL, vldt->conf, NXT_CONF_VLDT_OBJECT);
     if (ret != NXT_OK) {
         return ret;
@@ -1342,7 +1347,7 @@ nxt_conf_vldt_var(nxt_conf_validation_t *vldt, nxt_str_t *name,
 {
     u_char  error[NXT_MAX_ERROR_STR];
 
-    if (nxt_var_test(value, error) != NXT_OK) {
+    if (nxt_var_test(value, vldt->var_fields, error) != NXT_OK) {
         return nxt_conf_vldt_error(vldt, "%s in the \"%V\" value.",
                                    error, name);
     }
diff --git a/src/nxt_http.h b/src/nxt_http.h
index 4064a8a5..c2e85840 100644
--- a/src/nxt_http.h
+++ b/src/nxt_http.h
@@ -339,6 +339,9 @@ nxt_array_t *nxt_http_cookies_parse(nxt_http_request_t *r);
 
 int64_t nxt_http_field_hash(nxt_mp_t *mp, nxt_str_t *name,
     nxt_bool_t case_sensitive, uint8_t encoding);
+int64_t nxt_http_argument_hash(nxt_mp_t *mp, nxt_str_t *name);
+int64_t nxt_http_header_hash(nxt_mp_t *mp, nxt_str_t *name);
+int64_t nxt_http_cookie_hash(nxt_mp_t *mp, nxt_str_t *name);
 
 nxt_http_routes_t *nxt_http_routes_create(nxt_task_t *task,
     nxt_router_temp_conf_t *tmcf, nxt_conf_value_t *routes_conf);
@@ -369,8 +372,8 @@ nxt_int_t nxt_upstreams_create(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
 nxt_int_t nxt_upstreams_joint_create(nxt_router_temp_conf_t *tmcf,
     nxt_upstream_t ***upstream_joint);
 
-nxt_int_t nxt_http_return_init(nxt_mp_t *mp, nxt_http_action_t *action,
-    nxt_http_action_conf_t *acf);
+nxt_int_t nxt_http_return_init(nxt_router_conf_t *rtcf,
+    nxt_http_action_t *action, nxt_http_action_conf_t *acf);
 
 nxt_int_t nxt_http_static_init(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
     nxt_http_action_t *action, nxt_http_action_conf_t *acf);
diff --git a/src/nxt_http_request.c b/src/nxt_http_request.c
index 8aa20e59..5f8fd8f7 100644
--- a/src/nxt_http_request.c
+++ b/src/nxt_http_request.c
@@ -1180,3 +1180,57 @@ end:
 
     return nxt_http_field_hash_end(hash) & 0xFFFF;
 }
+
+
+int64_t
+nxt_http_argument_hash(nxt_mp_t *mp, nxt_str_t *name)
+{
+    return nxt_http_field_hash(mp, name, 1, NXT_HTTP_URI_ENCODING_PLUS);
+}
+
+
+int64_t
+nxt_http_header_hash(nxt_mp_t *mp, nxt_str_t *name)
+{
+    u_char     c, *p;
+    uint32_t   i, hash;
+    nxt_str_t  str;
+
+    str.length = name->length;
+
+    str.start = nxt_mp_nget(mp, str.length);
+    if (nxt_slow_path(str.start == NULL)) {
+        return -1;
+    }
+
+    p = str.start;
+    hash = NXT_HTTP_FIELD_HASH_INIT;
+
+    for (i = 0; i < name->length; i++) {
+        c = name->start[i];
+
+        if (c >= 'A' && c <= 'Z') {
+            *p = c | 0x20;
+
+        } else if (c == '_') {
+            *p = '-';
+
+        } else {
+            *p = c;
+        }
+
+        hash = nxt_http_field_hash_char(hash, *p);
+        p++;
+    }
+
+    *name = str;
+
+    return nxt_http_field_hash_end(hash) & 0xFFFF;
+}
+
+
+int64_t
+nxt_http_cookie_hash(nxt_mp_t *mp, nxt_str_t *name)
+{
+    return nxt_http_field_hash(mp, name, 1, NXT_HTTP_URI_ENCODING_NONE);
+}
diff --git a/src/nxt_http_return.c b/src/nxt_http_return.c
index 82c91568..9f3c4fc5 100644
--- a/src/nxt_http_return.c
+++ b/src/nxt_http_return.c
@@ -32,12 +32,15 @@ static const nxt_http_request_state_t  nxt_http_return_send_state;
 
 
 nxt_int_t
-nxt_http_return_init(nxt_mp_t *mp, nxt_http_action_t *action,
+nxt_http_return_init(nxt_router_conf_t *rtcf, nxt_http_action_t *action,
     nxt_http_action_conf_t *acf)
 {
+    nxt_mp_t                *mp;
     nxt_str_t               str;
     nxt_http_return_conf_t  *conf;
 
+    mp = rtcf->mem_pool;
+
     conf = nxt_mp_zget(mp, sizeof(nxt_http_return_conf_t));
     if (nxt_slow_path(conf == NULL)) {
         return NXT_ERROR;
@@ -54,7 +57,7 @@ nxt_http_return_init(nxt_mp_t *mp, nxt_http_action_t *action,
 
     nxt_conf_get_string(acf->location, &str);
 
-    conf->location = nxt_var_compile(&str, mp, 0);
+    conf->location = nxt_var_compile(&str, mp, rtcf->var_fields, 0);
     if (nxt_slow_path(conf->location == NULL)) {
         return NXT_ERROR;
     }
diff --git a/src/nxt_http_route.c b/src/nxt_http_route.c
index 5a4f349e..e00c37fe 100644
--- a/src/nxt_http_route.c
+++ b/src/nxt_http_route.c
@@ -643,6 +643,7 @@ nxt_http_action_init(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
     nxt_mp_t                *mp;
     nxt_int_t               ret;
     nxt_str_t               pass;
+    nxt_router_conf_t       *rtcf;
     nxt_http_action_conf_t  acf;
 
     nxt_memzero(&acf, sizeof(acf));
@@ -655,10 +656,11 @@ nxt_http_action_init(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
 
     nxt_memzero(action, sizeof(nxt_http_action_t));
 
-    mp = tmcf->router_conf->mem_pool;
+    rtcf = tmcf->router_conf;
+    mp = rtcf->mem_pool;
 
     if (acf.ret != NULL) {
-        return nxt_http_return_init(mp, action, &acf);
+        return nxt_http_return_init(rtcf, action, &acf);
     }
 
     if (acf.share != NULL) {
@@ -671,7 +673,7 @@ nxt_http_action_init(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
 
     nxt_conf_get_string(acf.pass, &pass);
 
-    action->u.var = nxt_var_compile(&pass, mp, 0);
+    action->u.var = nxt_var_compile(&pass, mp, rtcf->var_fields, 0);
     if (nxt_slow_path(action->u.var == NULL)) {
         return NXT_ERROR;
     }
@@ -1484,16 +1486,18 @@ nxt_http_action_create(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
 {
     nxt_mp_t           *mp;
     nxt_int_t          ret;
+    nxt_router_conf_t  *rtcf;
     nxt_http_action_t  *action;
 
-    mp = tmcf->router_conf->mem_pool;
+    rtcf = tmcf->router_conf;
+    mp = rtcf->mem_pool;
 
     action = nxt_mp_alloc(mp, sizeof(nxt_http_action_t));
     if (nxt_slow_path(action == NULL)) {
         return NULL;
     }
 
-    action->u.var = nxt_var_compile(pass, mp, 0);
+    action->u.var = nxt_var_compile(pass, mp, rtcf->var_fields, 0);
     if (nxt_slow_path(action->u.var == NULL)) {
         return NULL;
     }
diff --git a/src/nxt_http_static.c b/src/nxt_http_static.c
index 387cdec0..19393f2c 100644
--- a/src/nxt_http_static.c
+++ b/src/nxt_http_static.c
@@ -79,9 +79,11 @@ nxt_http_static_init(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
     nxt_str_t               str, *ret;
     nxt_var_t               *var;
     nxt_conf_value_t        *cv;
+    nxt_router_conf_t       *rtcf;
     nxt_http_static_conf_t  *conf;
 
-    mp = tmcf->router_conf->mem_pool;
+    rtcf = tmcf->router_conf;
+    mp = rtcf->mem_pool;
 
     conf = nxt_mp_zget(mp, sizeof(nxt_http_static_conf_t));
     if (nxt_slow_path(conf == NULL)) {
@@ -102,7 +104,7 @@ nxt_http_static_init(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
         cv = nxt_conf_get_array_element_or_itself(acf->share, i);
         nxt_conf_get_string(cv, &str);
 
-        var = nxt_var_compile(&str, mp, 1);
+        var = nxt_var_compile(&str, mp, rtcf->var_fields, 1);
         if (nxt_slow_path(var == NULL)) {
             return NXT_ERROR;
         }
@@ -128,7 +130,7 @@ nxt_http_static_init(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
         nxt_str_t   chr, shr;
         nxt_bool_t  is_const;
 
-        conf->chroot = nxt_var_compile(&acf->chroot, mp, 1);
+        conf->chroot = nxt_var_compile(&acf->chroot, mp, rtcf->var_fields, 1);
         if (nxt_slow_path(conf->chroot == NULL)) {
             return NXT_ERROR;
         }
diff --git a/src/nxt_http_variables.c b/src/nxt_http_variables.c
index c48f9ca3..79e66668 100644
--- a/src/nxt_http_variables.c
+++ b/src/nxt_http_variables.c
@@ -8,29 +8,47 @@
 
 
 static nxt_int_t nxt_http_var_method(nxt_task_t *task, nxt_str_t *str,
-    void *ctx);
+    void *ctx, uint16_t field);
 static nxt_int_t nxt_http_var_request_uri(nxt_task_t *task, nxt_str_t *str,
-    void *ctx);
-static nxt_int_t nxt_http_var_uri(nxt_task_t *task, nxt_str_t *str, void *ctx);
-static nxt_int_t nxt_http_var_host(nxt_task_t *task, nxt_str_t *str, void *ctx);
+    void *ctx, uint16_t field);
+static nxt_int_t nxt_http_var_uri(nxt_task_t *task, nxt_str_t *str, void *ctx,
+    uint16_t field);
+static nxt_int_t nxt_http_var_host(nxt_task_t *task, nxt_str_t *str, void *ctx,
+    uint16_t field);
+static nxt_int_t nxt_http_var_arg(nxt_task_t *task, nxt_str_t *str, void *ctx,
+    uint16_t field);
+static nxt_int_t nxt_http_var_header(nxt_task_t *task, nxt_str_t *str,
+    void *ctx, uint16_t field);
+static nxt_int_t nxt_http_var_cookie(nxt_task_t *task, nxt_str_t *str,
+    void *ctx, uint16_t field);
 
 
 static nxt_var_decl_t  nxt_http_vars[] = {
-    { nxt_string("method"),
-      &nxt_http_var_method,
-      0 },
-
-    { nxt_string("request_uri"),
-      &nxt_http_var_request_uri,
-      0 },
-
-    { nxt_string("uri"),
-      &nxt_http_var_uri,
-      0 },
-
-    { nxt_string("host"),
-      &nxt_http_var_host,
-      0 },
+    {
+        .name = nxt_string("method"),
+        .handler = nxt_http_var_method,
+    }, {
+        .name = nxt_string("request_uri"),
+        .handler = nxt_http_var_request_uri,
+    }, {
+        .name = nxt_string("uri"),
+        .handler = nxt_http_var_uri,
+    }, {
+        .name = nxt_string("host"),
+        .handler = nxt_http_var_host,
+    }, {
+        .name = nxt_string("arg"),
+        .handler = nxt_http_var_arg,
+        .field_hash = nxt_http_argument_hash,
+    }, {
+        .name = nxt_string("header"),
+        .handler = nxt_http_var_header,
+        .field_hash = nxt_http_header_hash,
+    }, {
+        .name = nxt_string("cookie"),
+        .handler = nxt_http_var_cookie,
+        .field_hash = nxt_http_cookie_hash,
+    },
 };
 
 
@@ -42,7 +60,7 @@ nxt_http_register_variables(void)
 
 
 static nxt_int_t
-nxt_http_var_method(nxt_task_t *task, nxt_str_t *str, void *ctx)
+nxt_http_var_method(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
 {
     nxt_http_request_t  *r;
 
@@ -55,7 +73,8 @@ nxt_http_var_method(nxt_task_t *task, nxt_str_t *str, void *ctx)
 
 
 static nxt_int_t
-nxt_http_var_request_uri(nxt_task_t *task, nxt_str_t *str, void *ctx)
+nxt_http_var_request_uri(nxt_task_t *task, nxt_str_t *str, void *ctx,
+    uint16_t field)
 {
     nxt_http_request_t  *r;
 
@@ -68,7 +87,7 @@ nxt_http_var_request_uri(nxt_task_t *task, nxt_str_t *str, void *ctx)
 
 
 static nxt_int_t
-nxt_http_var_uri(nxt_task_t *task, nxt_str_t *str, void *ctx)
+nxt_http_var_uri(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
 {
     nxt_http_request_t  *r;
 
@@ -81,7 +100,7 @@ nxt_http_var_uri(nxt_task_t *task, nxt_str_t *str, void *ctx)
 
 
 static nxt_int_t
-nxt_http_var_host(nxt_task_t *task, nxt_str_t *str, void *ctx)
+nxt_http_var_host(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
 {
     nxt_http_request_t  *r;
 
@@ -91,3 +110,125 @@ nxt_http_var_host(nxt_task_t *task, nxt_str_t *str, void *ctx)
 
     return NXT_OK;
 }
+
+
+static nxt_int_t
+nxt_http_var_arg(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
+{
+    nxt_array_t            *args;
+    nxt_var_field_t        *vf;
+    nxt_router_conf_t      *rtcf;
+    nxt_http_request_t     *r;
+    nxt_http_name_value_t  *nv, *start;
+
+    r = ctx;
+
+    rtcf = r->conf->socket_conf->router_conf;
+
+    vf = nxt_var_field_get(rtcf->var_fields, field);
+
+    args = nxt_http_arguments_parse(r);
+    if (nxt_slow_path(args == NULL)) {
+        return NXT_ERROR;
+    }
+
+    start = args->elts;
+    nv = start + args->nelts - 1;
+
+    while (nv >= start) {
+
+        if (vf->hash == nv->hash
+            && vf->name.length == nv->name_length
+            && nxt_memcmp(vf->name.start, nv->name, nv->name_length) == 0)
+        {
+            str->start = nv->value;
+            str->length = nv->value_length;
+
+            return NXT_OK;
+        }
+
+        nv--;
+    }
+
+    nxt_str_null(str);
+
+    return NXT_OK;
+}
+
+
+static nxt_int_t
+nxt_http_var_header(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
+{
+    nxt_var_field_t     *vf;
+    nxt_http_field_t    *f;
+    nxt_router_conf_t   *rtcf;
+    nxt_http_request_t  *r;
+
+    r = ctx;
+
+    rtcf = r->conf->socket_conf->router_conf;
+
+    vf = nxt_var_field_get(rtcf->var_fields, field);
+
+    nxt_list_each(f, r->fields) {
+
+        if (vf->hash == f->hash
+            && vf->name.length == f->name_length
+            && nxt_strncasecmp(vf->name.start, f->name, f->name_length) == 0)
+        {
+            str->start = f->value;
+            str->length = f->value_length;
+
+            return NXT_OK;
+        }
+
+    } nxt_list_loop;
+
+    nxt_str_null(str);
+
+    return NXT_OK;
+}
+
+
+static nxt_int_t
+nxt_http_var_cookie(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
+{
+    nxt_array_t            *cookies;
+    nxt_var_field_t        *vf;
+    nxt_router_conf_t      *rtcf;
+    nxt_http_request_t     *r;
+    nxt_http_name_value_t  *nv, *end;
+
+    r = ctx;
+
+    rtcf = r->conf->socket_conf->router_conf;
+
+    vf = nxt_var_field_get(rtcf->var_fields, field);
+
+    cookies = nxt_http_cookies_parse(r);
+    if (nxt_slow_path(cookies == NULL)) {
+        return NXT_ERROR;
+    }
+
+    nv = cookies->elts;
+    end = nv + cookies->nelts;
+
+    while (nv < end) {
+
+        if (vf->hash == nv->hash
+            && vf->name.length == nv->name_length
+            && nxt_memcmp(vf->name.start, nv->name, nv->name_length) == 0)
+        {
+            str->start = nv->value;
+            str->length = nv->value_length;
+
+            return NXT_OK;
+        }
+
+        nv++;
+    }
+
+    nxt_str_null(str);
+
+    return NXT_OK;
+}
diff --git a/src/nxt_router.c b/src/nxt_router.c
index a3cc0a8d..e84b3d9a 100644
--- a/src/nxt_router.c
+++ b/src/nxt_router.c
@@ -1004,6 +1004,11 @@ nxt_router_temp_conf(nxt_task_t *task)
 
     rtcf->mem_pool = mp;
 
+    rtcf->var_fields = nxt_array_create(mp, 4, sizeof(nxt_var_field_t));
+    if (nxt_slow_path(rtcf->var_fields == NULL)) {
+        goto fail;
+    }
+
     tmp = nxt_mp_create(1024, 128, 256, 32);
     if (nxt_slow_path(tmp == NULL)) {
         goto fail;
diff --git a/src/nxt_router.h b/src/nxt_router.h
index 37008f9d..8c21a70a 100644
--- a/src/nxt_router.h
+++ b/src/nxt_router.h
@@ -43,6 +43,7 @@ typedef struct {
     uint32_t                 threads;
 
     nxt_mp_t                 *mem_pool;
+    nxt_array_t              *var_fields;  /* of nxt_var_field_t */
 
     nxt_router_t             *router;
     nxt_http_routes_t        *routes;
diff --git a/src/nxt_var.c b/src/nxt_var.c
index 05cd6fd2..d3057764 100644
--- a/src/nxt_var.c
+++ b/src/nxt_var.c
@@ -52,6 +52,11 @@ struct nxt_var_query_s {
 static nxt_int_t nxt_var_hash_test(nxt_lvlhsh_query_t *lhq, void *data);
 static nxt_var_decl_t *nxt_var_hash_find(nxt_str_t *name);
 
+static nxt_var_decl_t *nxt_var_decl_get(nxt_str_t *name, nxt_array_t *fields,
+    uint32_t *index);
+static nxt_var_field_t *nxt_var_field_add(nxt_array_t *fields, nxt_str_t *name,
+    uint32_t hash);
+
 static nxt_int_t nxt_var_cache_test(nxt_lvlhsh_query_t *lhq, void *data);
 static nxt_str_t *nxt_var_cache_value(nxt_task_t *task, nxt_var_query_t *query,
     uint32_t index);
@@ -109,6 +114,117 @@ nxt_var_hash_find(nxt_str_t *name)
 }
 
 
+static nxt_var_decl_t *
+nxt_var_decl_get(nxt_str_t *name, nxt_array_t *fields, uint32_t *index)
+{
+    u_char           *p, *end;
+    int64_t          hash;
+    uint16_t         field;
+    nxt_str_t        str;
+    nxt_var_decl_t   *decl;
+    nxt_var_field_t  *f;
+
+    f = NULL;
+    field = 0;
+    decl = nxt_var_hash_find(name);
+
+    if (decl == NULL) {
+        p = name->start;
+        end = p + name->length;
+
+        while (p < end) {
+            if (*p++ == '_') {
+                break;
+            }
+        }
+
+        if (p == end) {
+            return NULL;
+        }
+
+        str.start = name->start;
+        str.length = p - 1 - name->start;
+
+        decl = nxt_var_hash_find(&str);
+
+        if (decl != NULL) {
+            str.start = p;
+            str.length = end - p;
+
+            hash = decl->field_hash(fields->mem_pool, &str);
+            if (nxt_slow_path(hash == -1)) {
+                return NULL;
+            }
+
+            f = nxt_var_field_add(fields, &str, (uint32_t) hash);
+            if (nxt_slow_path(f == NULL)) {
+                return NULL;
+            }
+
+            field = f->index;
+        }
+    }
+
+    if (decl != NULL) {
+        if (decl->field_hash != NULL && f == NULL) {
+            return NULL;
+        }
+
+        if (index != NULL) {
+            *index = (decl->index << 16) | field;
+        }
+    }
+
+    return decl;
+}
+
+
+static nxt_var_field_t *
+nxt_var_field_add(nxt_array_t *fields, nxt_str_t *name, uint32_t hash)
+{
+    nxt_uint_t       i;
+    nxt_var_field_t  *field;
+
+    field = fields->elts;
+
+    for (i = 0; i < fields->nelts; i++) {
+        if (field[i].hash == hash
+            && nxt_strstr_eq(&field[i].name, name))
+        {
+            return field;
+        }
+    }
+
+    field = nxt_array_add(fields);
+    if (nxt_slow_path(field == NULL)) {
+        return NULL;
+    }
+
+    field->name = *name;
+    field->hash = hash;
+    field->index = fields->nelts - 1;
+
+    return field;
+}
+
+
+nxt_var_field_t *
+nxt_var_field_get(nxt_array_t *fields, uint16_t index)
+{
+    nxt_uint_t       nfields;
+    nxt_var_field_t  *field;
+
+    field = fields->elts;
+    nfields = fields->nelts;
+
+    if (nfields > 0 && index <= nfields) {
+        return &field[index];
+    }
+
+    return NULL;
+}
+
+
 static nxt_int_t
 nxt_var_cache_test(nxt_lvlhsh_query_t *lhq, void *data)
 {
@@ -148,7 +264,8 @@ nxt_var_cache_value(nxt_task_t *task, nxt_var_query_t *query, uint32_t index)
     }
 
     if (ret == NXT_OK) {
-        ret = nxt_var_index[index](task, value, query->ctx);
+        ret = nxt_var_index[index >> 16](task, value, query->ctx,
+                                         index & 0xffff);
         if (nxt_slow_path(ret != NXT_OK)) {
             return NULL;
         }
@@ -213,10 +330,12 @@ nxt_var_index_init(void)
 
 
 nxt_var_t *
-nxt_var_compile(nxt_str_t *str, nxt_mp_t *mp, nxt_bool_t strz)
+nxt_var_compile(nxt_str_t *str, nxt_mp_t *mp, nxt_array_t *fields,
+    nxt_bool_t strz)
 {
     u_char          *p, *end, *next, *src;
     size_t          size;
+    uint32_t        index;
     nxt_var_t       *var;
     nxt_str_t       part;
     nxt_uint_t      n;
@@ -267,12 +386,12 @@ nxt_var_compile(nxt_str_t *str, nxt_mp_t *mp, nxt_bool_t strz)
         next = nxt_var_next_part(p, end - p, &part, &is_var);
 
         if (is_var) {
-            decl = nxt_var_hash_find(&part);
+            decl = nxt_var_decl_get(&part, fields, &index);
             if (nxt_slow_path(decl == NULL)) {
                 return NULL;
             }
 
-            subs[n].index = decl->index;
+            subs[n].index = index;
             subs[n].length = next - p;
             subs[n].position = p - str->start;
 
@@ -287,7 +406,7 @@ nxt_var_compile(nxt_str_t *str, nxt_mp_t *mp, nxt_bool_t strz)
 
 
 nxt_int_t
-nxt_var_test(nxt_str_t *str, u_char *error)
+nxt_var_test(nxt_str_t *str, nxt_array_t *fields, u_char *error)
 {
     u_char          *p, *end, *next;
     nxt_str_t       part;
@@ -308,7 +427,7 @@ nxt_var_test(nxt_str_t *str, u_char *error)
         }
 
         if (is_var) {
-            decl = nxt_var_hash_find(&part);
+            decl = nxt_var_decl_get(&part, fields, NULL);
 
             if (decl == NULL) {
                 nxt_sprintf(error, error + NXT_MAX_ERROR_STR,
diff --git a/src/nxt_var.h b/src/nxt_var.h
index 1322d507..3c38be36 100644
--- a/src/nxt_var.h
+++ b/src/nxt_var.h
@@ -13,15 +13,25 @@ typedef struct nxt_var_query_s  nxt_var_query_t;
 
 typedef nxt_int_t (*nxt_var_handler_t)(nxt_task_t *task,
                                        nxt_str_t *str,
-                                       void *ctx);
+                                       void *ctx, uint16_t field);
+
+typedef int64_t (*nxt_var_field_hash_t)(nxt_mp_t *mp, nxt_str_t *str);
 
 typedef struct {
-    nxt_str_t          name;
-    nxt_var_handler_t  handler;
-    uint32_t           index;
+    nxt_str_t               name;
+    nxt_var_handler_t       handler;
+    nxt_var_field_hash_t    field_hash;
+    uint32_t                index;
 } nxt_var_decl_t;
 
 
+typedef struct {
+    nxt_str_t               name;
+    uint16_t                hash;
+    uint32_t                index;
+} nxt_var_field_t;
+
+
 nxt_inline nxt_bool_t
 nxt_is_var(nxt_str_t *str)
 {
@@ -31,11 +41,15 @@ nxt_is_var(nxt_str_t *str)
 
 nxt_int_t nxt_var_register(nxt_var_decl_t *decl, size_t n);
 nxt_int_t nxt_var_index_init(void);
-nxt_var_t *nxt_var_compile(nxt_str_t *str, nxt_mp_t *mp, nxt_bool_t strz);
-nxt_int_t nxt_var_test(nxt_str_t *str, u_char *error);
 
-void nxt_var_raw(nxt_var_t *var, nxt_str_t *str);
+nxt_var_field_t *nxt_var_field_get(nxt_array_t *fields, uint16_t index);
+
+nxt_var_t *nxt_var_compile(nxt_str_t *str, nxt_mp_t *mp, nxt_array_t *fields,
+    nxt_bool_t strz);
+nxt_int_t nxt_var_test(nxt_str_t *str, nxt_array_t *fields, u_char *error);
+
 nxt_bool_t nxt_var_is_const(nxt_var_t *var);
+void nxt_var_raw(nxt_var_t *var, nxt_str_t *str);
 
 nxt_int_t nxt_var_query_init(nxt_var_query_t **query_p, void *ctx,
     nxt_mp_t *mp);