bugfix: ngx.resp.get_headers(): may return a wrong (like: negative) value of the Content-Length field when it is larger than 2^32.

Author: LubinLew

src/ngx_http_lua_headers.c

@@ -424,6 +424,8 @@ ngx_http_lua_ngx_resp_get_headers(lua_State *L)
     int                 count = 0;
     int                 truncated = 0;
     int                 extra = 0;
+    u_char             *p = NULL;
+    size_t              len = 0;
 
     n = lua_gettop(L);
 
@@ -485,7 +487,21 @@ ngx_http_lua_ngx_resp_get_headers(lua_State *L)
     {
         extra++;
         lua_pushliteral(L, "content-length");
-        lua_pushfstring(L, "%d", (int) r->headers_out.content_length_n);
+        if (r->headers_out.content_length_n > NGX_MAX_INT32_VALUE) {
+            p = ngx_palloc(r->pool, NGX_OFF_T_LEN);
+            if (p == NULL) {
+                return luaL_error(L, "no memory");
+            }
+
+            len = ngx_snprintf(p, NGX_OFF_T_LEN, "%O",
+                               r->headers_out.content_length_n) - p;
+
+            lua_pushfstring(L, "%s", (char *) p, len);
+
+        } else {
+            lua_pushfstring(L, "%d", (int) r->headers_out.content_length_n);
+        }
+
         lua_rawset(L, -3);
     }
 

t/016-resp-header.t

@@ -8,7 +8,7 @@ use Test::Nginx::Socket::Lua;
 
 repeat_each(2);
 
-plan tests => repeat_each() * (blocks() * 3 + 77);
+plan tests => repeat_each() * (blocks() * 3 + 79);
 
 #no_diff();
 no_long_string();
@@ -2104,3 +2104,40 @@ xxx:
 foo: foo%0Axx:bar\r\nfoo: bar%0Dxxx:foo\r\n
 --- no_error_log
 [error]
+
+
+
+=== TEST 94: fix negative content-length number(#1791)
+--- config
+    location = /big-upstream {
+        content_by_lua_block {
+            ngx.header['Content-Length'] = math.pow(2, 33) - 1
+            ngx.say('hi')
+        }
+    }
+
+    location = /t {
+        proxy_pass http://127.0.0.1:$TEST_NGINX_SERVER_PORT/big-upstream;
+        proxy_buffering off;
+
+        header_filter_by_lua_block {
+            local hs, err = ngx.resp.get_headers()
+            if err then
+                ngx.log(ngx.ERR, "err: ", err)
+                return ngx.exit(500)
+            end
+
+            print("my Content-Length: ", hs["Content-Length"])
+
+            ngx.header['Content-Length'] = 3
+        }
+    }
+--- request
+    GET /t
+--- response_body
+hi
+--- no_error_log
+[alert]
+--- error_log
+my Content-Length: 8589934591
+upstream prematurely closed connection while sending to client