feature:added new API function ngx.resp.get_headers for getting all response headers

README.markdown

@@ -94,6 +94,7 @@ Table of Contents
     * [ngx.req.append_body](#ngxreqappend_body)
     * [ngx.req.finish_body](#ngxreqfinish_body)
     * [ngx.req.socket](#ngxreqsocket)
+    * [ngx.resp.get_headers](#ngxrespget_headers)
     * [ngx.exec](#ngxexec)
     * [ngx.redirect](#ngxredirect)
     * [ngx.send_headers](#ngxsend_headers)
@@ -3277,6 +3278,33 @@ This function was first introduced in the `v0.5.0rc1` release.
 
 [Back to TOC](#table-of-contents)
 
+ngx.resp.get_headers
+--------------------
+**syntax:** *headers = ngx.resp.get_headers(max_headers?, raw?)*
+
+**context:** *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua, log_by_lua**
+
+Returns a Lua table holding all the current response headers.
+
+```lua
+
+local h = ngx.resp.get_headers()
+for k, v in pairs(h) do
+    ...
+end
+```
+
+To read an individual header:
+
+```lua
+
+ngx.say("ETag: ", ngx.resp.get_headers()["ETag"])
+```
+
+This function has the same signature as [ngx.req.get_headers](#ngxreqget_headers) except getting response headers instead of request headers.
+
+[Back to TOC](#table-of-contents)
+
 ngx.exec
 --------
 **syntax:** *ngx.exec(uri, args?)*

src/ngx_http_lua_headers.c

@@ -25,6 +25,7 @@ static int ngx_http_lua_ngx_header_set(lua_State *L);
 static int ngx_http_lua_ngx_req_get_headers(lua_State *L);
 static int ngx_http_lua_ngx_req_header_clear(lua_State *L);
 static int ngx_http_lua_ngx_req_header_set(lua_State *L);
+static int ngx_http_lua_ngx_resp_get_headers(lua_State *L);
 
 
 static int
@@ -338,7 +339,7 @@ ngx_http_lua_ngx_req_get_headers(lua_State *L)
     lua_createtable(L, 0, count);
 
     if (!raw) {
-        lua_pushlightuserdata(L, &ngx_http_lua_req_get_headers_metatable_key);
+        lua_pushlightuserdata(L, &ngx_http_lua_get_headers_metatable_key);
         lua_rawget(L, LUA_REGISTRYINDEX);
         lua_setmetatable(L, -2);
     }
@@ -388,6 +389,127 @@ ngx_http_lua_ngx_req_get_headers(lua_State *L)
 }
 
 
+static int
+ngx_http_lua_ngx_resp_get_headers(lua_State *L)
+{
+    ngx_list_part_t    *part;
+    ngx_table_elt_t    *header;
+    ngx_http_request_t *r;
+    u_char             *lowcase_key = NULL;
+    size_t              lowcase_key_sz = 0;
+    ngx_uint_t          i;
+    int                 n;
+    int                 max;
+    int                 raw = 0;
+    int                 count = 0;
+
+    n = lua_gettop(L);
+
+    if (n >= 1) {
+        if (lua_isnil(L, 1)) {
+            max = NGX_HTTP_LUA_MAX_HEADERS;
+
+        } else {
+            max = luaL_checkinteger(L, 1);
+        }
+
+        if (n >= 2) {
+            raw = lua_toboolean(L, 2);
+        }
+
+    } else {
+        max = NGX_HTTP_LUA_MAX_HEADERS;
+    }
+
+    r = ngx_http_lua_get_req(L);
+    if (r == NULL) {
+        return luaL_error(L, "no request object found");
+    }
+
+    ngx_http_lua_check_fake_request(L, r);
+
+    part = &r->headers_out.headers.part;
+    count = part->nelts;
+    while (part->next) {
+        part = part->next;
+        count += part->nelts;
+    }
+
+    if (max > 0 && count > max) {
+        count = max;
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "lua exceeding request header limit %d", max);
+    }
+
+    lua_createtable(L, 0, count);
+
+    if (!raw) {
+        lua_pushlightuserdata(L, &ngx_http_lua_get_headers_metatable_key);
+        lua_rawget(L, LUA_REGISTRYINDEX);
+        lua_setmetatable(L, -2);
+    }
+
+    part = &r->headers_out.headers.part;
+    header = part->elts;
+
+    for (i = 0; /* void */; i++) {
+
+        dd("stack top: %d", lua_gettop(L));
+
+        if (i >= part->nelts) {
+            if (part->next == NULL) {
+                break;
+            }
+
+            part = part->next;
+            header = part->elts;
+            i = 0;
+        }
+
+        if (header[i].hash == 0) {
+            continue;
+        }
+
+        if (raw) {
+            lua_pushlstring(L, (char *) header[i].key.data, header[i].key.len);
+
+        } else {
+            /* nginx does not even bother initializing output header entry's
+             * "lowcase_key" field. so we cannot count on that at all. */
+            if (header[i].key.len > lowcase_key_sz) {
+                lowcase_key_sz = header[i].key.len * 2;
+
+                /* we allocate via Lua's GC to prevent in-request
+                 * leaks in the nginx request memory pools */
+                lowcase_key = lua_newuserdata(L, lowcase_key_sz);
+                lua_insert(L, 1);
+            }
+
+            ngx_strlow(lowcase_key, header[i].key.data, header[i].key.len);
+            lua_pushlstring(L, (char *) lowcase_key, header[i].key.len);
+        }
+
+        /* stack: [udata] table key */
+
+        lua_pushlstring(L, (char *) header[i].value.data,
+                        header[i].value.len); /* stack: [udata] table key
+                                                 value */
+
+        ngx_http_lua_set_multi_value_table(L, -3);
+
+        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "lua response header: \"%V: %V\"",
+                       &header[i].key, &header[i].value);
+
+        if (--count == 0) {
+            return 1;
+        }
+    }
+
+    return 1;
+}
+
+
 static int
 ngx_http_lua_ngx_header_get(lua_State *L)
 {
@@ -717,6 +839,27 @@ ngx_http_lua_ngx_req_header_set_helper(lua_State *L)
 }
 
 
+void
+ngx_http_lua_inject_req_header_api(lua_State *L)
+{
+    lua_pushcfunction(L, ngx_http_lua_ngx_req_http_version);
+    lua_setfield(L, -2, "http_version");
+
+    lua_pushcfunction(L, ngx_http_lua_ngx_req_raw_header);
+    lua_setfield(L, -2, "raw_header");
+
+    lua_pushcfunction(L, ngx_http_lua_ngx_req_header_clear);
+    lua_setfield(L, -2, "clear_header");
+
+    lua_pushcfunction(L, ngx_http_lua_ngx_req_header_set);
+    lua_setfield(L, -2, "set_header");
+
+    lua_pushcfunction(L, ngx_http_lua_ngx_req_get_headers);
+    lua_setfield(L, -2, "get_headers");
+
+}
+
+
 void
 ngx_http_lua_inject_resp_header_api(lua_State *L)
 {
@@ -730,53 +873,46 @@ ngx_http_lua_inject_resp_header_api(lua_State *L)
     lua_setmetatable(L, -2);
 
     lua_setfield(L, -2, "header");
-}
-
 
-void
-ngx_http_lua_inject_req_header_api(ngx_log_t *log, lua_State *L)
-{
-    int         rc;
 
-    lua_pushcfunction(L, ngx_http_lua_ngx_req_http_version);
-    lua_setfield(L, -2, "http_version");
+    lua_createtable(L, 0, 1); /* .resp */
 
-    lua_pushcfunction(L, ngx_http_lua_ngx_req_raw_header);
-    lua_setfield(L, -2, "raw_header");
-
-    lua_pushcfunction(L, ngx_http_lua_ngx_req_header_clear);
-    lua_setfield(L, -2, "clear_header");
+    lua_pushcfunction(L, ngx_http_lua_ngx_resp_get_headers);
+    lua_setfield(L, -2, "get_headers");
 
-    lua_pushcfunction(L, ngx_http_lua_ngx_req_header_set);
-    lua_setfield(L, -2, "set_header");
+    lua_setfield(L, -2, "resp");
+}
 
-    lua_pushcfunction(L, ngx_http_lua_ngx_req_get_headers);
-    lua_setfield(L, -2, "get_headers");
 
-    lua_pushlightuserdata(L, &ngx_http_lua_req_get_headers_metatable_key);
-    lua_createtable(L, 0, 1); /* metatable for ngx.req.get_headers(_, true) */
+void
+ngx_http_lua_inject_metatable_header_api(ngx_log_t *log, lua_State *L)
+{
+    int rc;
+    const char buf[] =
+        "local tb, key = ...\n"
+        "local new_key = string.gsub(string.lower(key), '_', '-')\n"
+        "if new_key ~= key then return tb[new_key] else return nil end";
 
-    {
-        const char buf[] =
-            "local tb, key = ...\n"
-            "local new_key = string.gsub(string.lower(key), '_', '-')\n"
-            "if new_key ~= key then return tb[new_key] else return nil end";
+    lua_pushlightuserdata(L, &ngx_http_lua_get_headers_metatable_key);
+    /* metatable for ngx.req.get_headers(_, true)
+     * and ngx.resp.get_headers(_, true) */
+    lua_createtable(L, 0, 1); 
 
-        rc = luaL_loadbuffer(L, buf, sizeof(buf) - 1,
-                             "ngx.req.get_headers __index");
-    }
+    rc = luaL_loadbuffer(L, buf, sizeof(buf) - 1,
+                         "ngx_req.get_headers and ngx.resp.get_headers __index");
 
     if (rc != 0) {
         ngx_log_error(NGX_LOG_ERR, log, 0,
                       "failed to load Lua code of the metamethod for "
-                      "ngx.req.get_headers: %i: %s", rc, lua_tostring(L, -1));
+                      "ngx.req.get_headers, ngx.resp.get_headers: %i: %s", rc, lua_tostring(L, -1));
 
         lua_pop(L, 3);
         return;
     }
 
     lua_setfield(L, -2, "__index");
     lua_rawset(L, LUA_REGISTRYINDEX);
+
 }
 
 

src/ngx_http_lua_headers.h

@@ -12,8 +12,9 @@
 #include "ngx_http_lua_common.h"
 
 
+void ngx_http_lua_inject_req_header_api(lua_State *L);
 void ngx_http_lua_inject_resp_header_api(lua_State *L);
-void ngx_http_lua_inject_req_header_api(ngx_log_t *log, lua_State *L);
+void ngx_http_lua_inject_metatable_header_api(ngx_log_t *log, lua_State *L);
 
 
 #endif /* _NGX_HTTP_LUA_HEADERS_H_INCLUDED_ */

src/ngx_http_lua_util.c

@@ -70,8 +70,7 @@ char ngx_http_lua_code_cache_key;
 char ngx_http_lua_regex_cache_key;
 char ngx_http_lua_socket_pool_key;
 char ngx_http_lua_coroutines_key;
-char ngx_http_lua_req_get_headers_metatable_key;
-
+char ngx_http_lua_get_headers_metatable_key;
 
 ngx_uint_t  ngx_http_lua_location_hash = 0;
 ngx_uint_t  ngx_http_lua_content_length_hash = 0;
@@ -782,7 +781,7 @@ static void
 ngx_http_lua_inject_ngx_api(lua_State *L, ngx_http_lua_main_conf_t *lmcf,
     ngx_log_t *log)
 {
-    lua_createtable(L, 0 /* narr */, 97 /* nrec */);    /* ngx.* */
+    lua_createtable(L, 0 /* narr */, 98 /* nrec */);    /* ngx.* */
 
     ngx_http_lua_inject_arg_api(L);
 
@@ -804,6 +803,7 @@ ngx_http_lua_inject_ngx_api(lua_State *L, ngx_http_lua_main_conf_t *lmcf,
 
     ngx_http_lua_inject_req_api(log, L);
     ngx_http_lua_inject_resp_header_api(L);
+    ngx_http_lua_inject_metatable_header_api(log, L);
     ngx_http_lua_inject_variable_api(L);
     ngx_http_lua_inject_shdict_api(lmcf, L);
     ngx_http_lua_inject_socket_tcp_api(log, L);
@@ -2151,7 +2151,7 @@ ngx_http_lua_inject_req_api(ngx_log_t *log, lua_State *L)
 
     lua_createtable(L, 0 /* narr */, 23 /* nrec */);    /* .req */
 
-    ngx_http_lua_inject_req_header_api(log, L);
+    ngx_http_lua_inject_req_header_api(L);
     ngx_http_lua_inject_req_uri_api(log, L);
     ngx_http_lua_inject_req_args_api(L);
     ngx_http_lua_inject_req_body_api(L);

src/ngx_http_lua_util.h

@@ -54,8 +54,8 @@ extern char ngx_http_lua_coroutine_parents_key;
 /* coroutine anchoring table key in Lua VM registry */
 extern char ngx_http_lua_coroutines_key;
 
-/* key to the metatable for ngx.req.get_headers() */
-extern char ngx_http_lua_req_get_headers_metatable_key;
+/* key to the metatable for ngx.req.get_headers() and ngx.resp.get_headers() */
+extern char ngx_http_lua_get_headers_metatable_key;
 
 
 #ifndef ngx_str_set