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[mod_magnet] allow modification of request headers

allow modification of request headers, with some limitations:
- lighttpd config conditions are not reset;
  lua script must return lighty.RESTART_REQUEST to reprocess request
  (if applicable to the running lighttpd config)
- lighttpd config request header policy is not applied;
  lua script must not set unvalidated, untrusted, or non-normalized vals
- Host may not be unset
- Content-Length may not be modified
- some hop-by-hop (connection) level headers may not be modified
  (e.g. Connection, Transfer-Encoding)
master
Glenn Strauss 3 months ago
parent
commit
bf05943258
  1. 68
      src/mod_magnet.c

68
src/mod_magnet.c

@ -603,6 +603,70 @@ static int magnet_reqhdr_get(lua_State *L) {
return 1;
}
static int magnet_reqhdr_set(lua_State *L) {
/* __newindex: param 1 is (empty) table in which value is to be set */
const_buffer k = magnet_checkconstbuffer(L, 2);
const_buffer v = magnet_checkconstbuffer(L, 3);
request_st * const r = magnet_get_request(L);
enum http_header_e id = http_header_hkey_get(k.ptr, (uint32_t)k.len);
switch (id) {
/*case HTTP_HEADER_OTHER:*/
default:
break;
case HTTP_HEADER_HOST:
/* do not allow Host to be unset, even if HTTP/1.0
* (change Host to something else, if you must */
if (0 == v.len) return 0;
/*(must set r->http_host if r->http_host was not previously set)*/
/* copied from request.c:http_request_header_set_Host() */
r->http_host = http_header_request_set_ptr(r, HTTP_HEADER_HOST,
CONST_STR_LEN("Host"));
buffer_copy_string_len_lc(r->http_host, v.ptr, v.len);
return 0;
case HTTP_HEADER_CONTENT_LENGTH:
/* not attempting to handle Content-Length modification; may revisit */
/* future: might permit setting to 0 to force discard of request body
* but would have to check if request body present, and if
* Content-Length was set, or if Transfer-Encoding: chunked,
* and handle resetting internal chunked encoding state,
* as well as making sure that this is handled properly for HTTP/2 */
return 0; /* silently ignore; do not allow modification */
/* do not permit modification of hop-by-hop (connection) headers */
case HTTP_HEADER_CONNECTION:
/* do not permit modification of Connection, incl add/remove tokens */
/* future: might provide a different interface to set r->keep_alive = 0,
* and also handle in context if HTTP/2 */
case HTTP_HEADER_TRANSFER_ENCODING:
case HTTP_HEADER_SET_COOKIE:/*(response hdr;avoid accidental reflection)*/
return 0; /* silently ignore; do not allow modification */
#if 0 /*(eh, if script sets Upgrade, script probably intends this action)*/
case HTTP_HEADER_UPGRADE:
/* note: modifications here do not modify Connection header
* to add or remove "upgrade" token */
/* future: might allow removal of existing tokens, but not addition */
if (0 != v.len) return 0; /* do not allow Upgrade other than to unset */
break;
#endif
#if 0 /*(eh, if script sets TE, script probably intends this action)*/
case HTTP_HEADER_TE:
if (0 != v.len) return 0; /* do not allow TE other than to unset */
break;
#endif
}
v.len
? http_header_request_set(r, id, k.ptr, k.len, v.ptr, v.len)
: http_header_request_unset(r, id, k.ptr, k.len);
return 0;
}
static int magnet_reqhdr_pairs(lua_State *L) {
request_st * const r = magnet_get_request(L);
return magnet_array_pairs(L, &r->rqst_headers);
@ -1099,9 +1163,11 @@ static void magnet_init_lighty_table(lua_State * const L) {
lua_createtable(L, 0, 9); /* lighty.* (returned on stack) (sp += 1) */
lua_createtable(L, 0, 0); /* {} (sp += 1) */
lua_createtable(L, 0, 3); /* metatable for request table (sp += 1) */
lua_createtable(L, 0, 4); /* metatable for request table (sp += 1) */
lua_pushcfunction(L, magnet_reqhdr_get); /* (sp += 1) */
lua_setfield(L, -2, "__index"); /* (sp -= 1) */
lua_pushcfunction(L, magnet_reqhdr_set); /* (sp += 1) */
lua_setfield(L, -2, "__newindex"); /* (sp -= 1) */
lua_pushcfunction(L, magnet_reqhdr_pairs); /* (sp += 1) */
lua_setfield(L, -2, "__pairs"); /* (sp -= 1) */
lua_pushboolean(L, 0); /* (sp += 1) */

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