added support for multi-value request headers in ngx.req.get_headers().

README.markdown

@@ -927,6 +927,16 @@ To read an individual header:
 
     ngx.say("Host: ", ngx.req.get_headers()["Host"])
 
+For multiple instances of request headers like
+
+    Foo: foo
+    Foo: bar
+    Foo: baz
+
+the value of `ngx.req.get_headers()["Foo"]` will be a Lua (array) table like this:
+
+    {"foo", "bar", "baz"}
+
 Another way to read individual request headers is to use `ngx.var.http_HEADER`, that is, nginx's standard $http_HEADER variables:
 
     http://wiki.nginx.org/NginxHttpCoreModule#.24http_HEADER

src/ngx_http_lua_hook.c

@@ -1956,7 +1956,7 @@ ngx_http_lua_ngx_req_get_headers(lua_State *L) {
         return luaL_error(L, "no request object found");
     }
 
-    lua_createtable(L, 0, 8); /* Firefox creates 8 headers in its requests */
+    lua_createtable(L, 0, 4);
 
     part = &r->headers_in.headers.part;
     header = part->elts;
@@ -1974,8 +1974,60 @@ ngx_http_lua_ngx_req_get_headers(lua_State *L) {
         }
 
         lua_pushlstring(L, (char *) header[i].key.data, header[i].key.len);
-        lua_pushlstring(L, (char *) header[i].value.data, header[i].value.len);
-        lua_rawset(L, -3);
+            /* stack: table key */
+
+        lua_pushvalue(L, -1); /* stack: table key key */
+
+        /* check if header already exists */
+        lua_rawget(L, -3); /* stack: table key value */
+
+        if (lua_isnil(L, -1)) {
+            dd("req.header key %.*s not exist", (int) header[i].key.len,
+                    header[i].key.data);
+
+            lua_pop(L, 1); /* stack: table key */
+
+            lua_pushlstring(L, (char *) header[i].value.data,
+                    header[i].value.len); /* stack: table key value */
+
+            lua_rawset(L, -3); /* stack: table */
+
+        } else {
+            dd("req.header key %.*s exists", (int) header[i].key.len,
+                    header[i].key.data);
+
+            if (! lua_istable(L, -1)) { /* already inserted one value */
+                dd("req.header key %.*s already has one value",
+                        (int) header[i].key.len, header[i].key.data);
+                lua_createtable(L, 4, 0);
+                    /* stack: table key value table */
+
+                lua_insert(L, -2); /* stack: table key table value */
+                lua_rawseti(L, -2, 1); /* stack: table key table */
+
+                lua_pushlstring(L, (char *) header[i].value.data,
+                        header[i].value.len);
+                    /* stack: table key table value */
+
+                lua_rawseti(L, -2, lua_objlen(L, -2) + 1);
+                    /* stack: table key table */
+
+                lua_rawset(L, -3); /* stack: table */
+
+            } else {
+                dd("req.header key %.*s already has multi values",
+                        (int) header[i].key.len, header[i].key.data);
+
+                lua_pushlstring(L, (char *) header[i].value.data,
+                        header[i].value.len);
+                    /* stack: table key table value */
+
+                lua_rawseti(L, -2, lua_objlen(L, -2) + 1);
+                    /* stack: table key table */
+
+                lua_pop(L, 2); /* stack: table */
+            }
+        }
 
         ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                        "http lua req header: \"%V: %V\"",

src/ngx_http_lua_util.c

@@ -525,7 +525,7 @@ init_ngx_lua_globals(lua_State *L)
     lua_setglobal(L, "ndk");
 #endif /* defined(NDK) && NDK */
 
-    lua_createtable(L, 0, 20);    /* ngx.* */
+    lua_createtable(L, 0, 22);    /* ngx.* */
 
     /* {{{ register nginx hook functions */
     lua_pushcfunction(L, ngx_http_lua_ngx_exec);

t/028-req-header.t

@@ -284,7 +284,7 @@ GET /bar
 
 
 
-=== TEST 15: set_header and clear_header should refresh ngx.req.header automatically
+=== TEST 15: set_header and clear_header should refresh ngx.req.get_headers() automatically
 --- config
     location /foo {
         content_by_lua '
@@ -310,3 +310,28 @@ Foo 1: 32
 Foo 2: abc
 Foo 3: nil
 
+
+
+=== TEST 16: duplicate req headers
+--- config
+    location /foo {
+        content_by_lua '
+            local vals = ngx.req.get_headers()["Foo"]
+            ngx.say("value is of type ", type(vals), ".")
+            if type(vals) == "table" then
+                ngx.say("Foo takes ", #vals or "nil", " values.")
+                ngx.say("They are ", table.concat(vals, ", "), ".")
+            end
+        ';
+    }
+--- more_headers
+Foo: foo
+Foo: bar
+Foo: baz
+--- request
+    GET /foo
+--- response_body
+value is of type table.
+Foo takes 3 values.
+They are foo, bar, baz.
+