Mirrors/libwebsockets
1
0
Fork 0
mirror of https://github.com/warmcat/libwebsockets.git synced 2025-03-23 00:00:06 +01:00
Code Issues Releases Wiki Activity
libwebsockets/lib/roles/ws/server-ws.c
Andy Green 4b7144f763 lws_buflist 
For h1 / ws, a combination of removing POLLIN wait and
stashing any unused rx lets us immediately respond to
rx flow control requests in a simple and effective way,
because the tcp socket is the stream.

But for muxed protocols like h2, that technique cannot
be used because we cannot silence the whole bundle of
streams because one can't handle any more rx dynamically.

There are control frames and content for other streams
serialized inbetween the flow controlled stream content.
We have no choice but to read to so we can see the other
things.  Therefore for muxed protocols like h2 and spdy,
rx flow control boils down to tx credit manipulation
on individual streams to staunch the flow at the peer.

However that requires a round trip to take effect, any
transmitted packets that were in flight before the tx credit
reduction arrives at the remote peer are still going to come
and have to be dealt with by adding them to the stash.

This patch introduces lws_buflist scatter-gather type
buffer management for rxflow handling, so we can append
buffer segments in a linked-list to handle whatever rx
is unavoidably in flight on a stream that is trying to
assert rx flow control.
2018-04-19 16:15:10 +08:00

626 lines
15 KiB
C
Raw Blame History

/*
* libwebsockets - small server side websockets and web server implementation
*
* Copyright (C) 2010-2018 Andy Green <andy@warmcat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation:
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#include <private-libwebsockets.h>
#define LWS_CPYAPP(ptr, str) { strcpy(ptr, str); ptr += strlen(str); }
#if !defined(LWS_WITHOUT_EXTENSIONS)
static int
lws_extension_server_handshake(struct lws *wsi, char **p, int budget)
{
struct lws_context *context = wsi->context;
struct lws_context_per_thread *pt = &context->pt[(int)wsi->tsi];
char ext_name[64], *args, *end = (*p) + budget - 1;
const struct lws_ext_options *opts, *po;
const struct lws_extension *ext;
struct lws_ext_option_arg oa;
int n, m, more = 1;
int ext_count = 0;
char ignore;
char *c;
/*
* Figure out which extensions the client has that we want to
* enable on this connection, and give him back the list
*/
if (!lws_hdr_total_length(wsi, WSI_TOKEN_EXTENSIONS))
return 0;
/*
* break down the list of client extensions
* and go through them
*/
if (lws_hdr_copy(wsi, (char *)pt->serv_buf, context->pt_serv_buf_size,
WSI_TOKEN_EXTENSIONS) < 0)
return 1;
c = (char *)pt->serv_buf;
lwsl_parser("WSI_TOKEN_EXTENSIONS = '%s'\n", c);
wsi->count_act_ext = 0;
ignore = 0;
n = 0;
args = NULL;
/*
* We may get a simple request
*
* Sec-WebSocket-Extensions: permessage-deflate
*
* or an elaborated one with requested options
*
* Sec-WebSocket-Extensions: permessage-deflate; \
* server_no_context_takeover; \
* client_no_context_takeover
*/
while (more) {
if (*c && (*c != ',' && *c != '\t')) {
if (*c == ';') {
ignore = 1;
args = c + 1;
}
if (ignore || *c == ' ') {
c++;
continue;
}
ext_name[n] = *c++;
if (n < (int)sizeof(ext_name) - 1)
n++;
continue;
}
ext_name[n] = '\0';
ignore = 0;
if (!*c)
more = 0;
else {
c++;
if (!n)
continue;
}
while (args && *args && *args == ' ')
args++;
/* check a client's extension against our support */
ext = wsi->vhost->extensions;
while (ext && ext->callback) {
if (strcmp(ext_name, ext->name)) {
ext++;
continue;
}
/*
* oh, we do support this one he asked for... but let's
* confirm he only gave it once
*/
for (m = 0; m < wsi->count_act_ext; m++)
if (wsi->active_extensions[m] == ext) {
lwsl_info("extension mentioned twice\n");
return 1; /* shenanigans */
}
/*
* ask user code if it's OK to apply it on this
* particular connection + protocol
*/
m = (wsi->protocol->callback)(wsi,
LWS_CALLBACK_CONFIRM_EXTENSION_OKAY,
wsi->user_space, ext_name, 0);
/*
* zero return from callback means go ahead and allow
* the extension, it's what we get if the callback is
* unhandled
*/
if (m) {
ext++;
continue;
}
/* apply it */
ext_count++;
/* instantiate the extension on this conn */
wsi->active_extensions[wsi->count_act_ext] = ext;
/* allow him to construct his context */
if (ext->callback(lws_get_context(wsi), ext, wsi,
LWS_EXT_CB_CONSTRUCT,
(void *)&wsi->act_ext_user[
wsi->count_act_ext],
(void *)&opts, 0)) {
lwsl_info("ext %s failed construction\n",
ext_name);
ext_count--;
ext++;
continue;
}
if (ext_count > 1)
*(*p)++ = ',';
else
LWS_CPYAPP(*p,
"\x0d\x0aSec-WebSocket-Extensions: ");
*p += lws_snprintf(*p, (end - *p), "%s", ext_name);
/*
* go through the options trying to apply the
* recognized ones
*/
lwsl_debug("ext args %s", args);
while (args && *args && *args != ',') {
while (*args == ' ')
args++;
po = opts;
while (po->name) {
/* only support arg-less options... */
if (po->type != EXTARG_NONE ||
strncmp(args, po->name,
strlen(po->name))) {
po++;
continue;
}
oa.option_name = NULL;
oa.option_index = (int)(po - opts);
oa.start = NULL;
lwsl_debug("setting %s\n", po->name);
if (!ext->callback(
lws_get_context(wsi), ext, wsi,
LWS_EXT_CB_OPTION_SET,
wsi->act_ext_user[
wsi->count_act_ext],
&oa, (end - *p))) {
*p += lws_snprintf(*p, (end - *p),
"; %s", po->name);
lwsl_debug("adding option %s\n",
po->name);
}
po++;
}
while (*args && *args != ',' && *args != ';')
args++;
}
wsi->count_act_ext++;
lwsl_parser("cnt_act_ext <- %d\n", wsi->count_act_ext);
ext++;
}
n = 0;
args = NULL;
}
return 0;
}
#endif
int
lws_process_ws_upgrade(struct lws *wsi)
{
struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
char protocol_list[128], protocol_name[64], *p;
int protocol_len, hit, n = 0, non_space_char_found = 0;
if (!wsi->protocol)
lwsl_err("NULL protocol at lws_read\n");
/*
* It's either websocket or h2->websocket
*
* Select the first protocol we support from the list
* the client sent us.
*
* Copy it to remove header fragmentation
*/
if (lws_hdr_copy(wsi, protocol_list, sizeof(protocol_list) - 1,
WSI_TOKEN_PROTOCOL) < 0) {
lwsl_err("protocol list too long");
return 1;
}
protocol_len = lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL);
protocol_list[protocol_len] = '\0';
p = protocol_list;
hit = 0;
while (*p && !hit) {
n = 0;
non_space_char_found = 0;
while (n < (int)sizeof(protocol_name) - 1 &&
*p && *p != ',') {
/* ignore leading spaces */
if (!non_space_char_found && *p == ' ') {
n++;
continue;
}
non_space_char_found = 1;
protocol_name[n++] = *p++;
}
protocol_name[n] = '\0';
if (*p)
p++;
lwsl_debug("checking %s\n", protocol_name);
n = 0;
while (wsi->vhost->protocols[n].callback) {
lwsl_debug("try %s\n",
wsi->vhost->protocols[n].name);
if (wsi->vhost->protocols[n].name &&
!strcmp(wsi->vhost->protocols[n].name,
protocol_name)) {
wsi->protocol = &wsi->vhost->protocols[n];
hit = 1;
break;
}
n++;
}
}
/* we didn't find a protocol he wanted? */
if (!hit) {
if (lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL)) {
lwsl_notice("No protocol from \"%s\" supported\n",
protocol_list);
return 1;
}
/*
* some clients only have one protocol and
* do not send the protocol list header...
* allow it and match to the vhost's default
* protocol (which itself defaults to zero)
*/
lwsl_info("defaulting to prot handler %d\n",
wsi->vhost->default_protocol_index);
n = wsi->vhost->default_protocol_index;
wsi->protocol = &wsi->vhost->protocols[
(int)wsi->vhost->default_protocol_index];
}
/* allocate the ws struct for the wsi */
wsi->ws = lws_zalloc(sizeof(*wsi->ws), "ws struct");
if (!wsi->ws) {
lwsl_notice("OOM\n");
return 1;
}
if (lws_hdr_total_length(wsi, WSI_TOKEN_VERSION))
wsi->ws->ietf_spec_revision =
atoi(lws_hdr_simple_ptr(wsi, WSI_TOKEN_VERSION));
/* allocate wsi->user storage */
if (lws_ensure_user_space(wsi)) {
lwsl_notice("problem with user space\n");
return 1;
}
/*
* Give the user code a chance to study the request and
* have the opportunity to deny it
*/
if ((wsi->protocol->callback)(wsi,
LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
wsi->user_space,
lws_hdr_simple_ptr(wsi, WSI_TOKEN_PROTOCOL), 0)) {
lwsl_warn("User code denied connection\n");
return 1;
}
/*
* Perform the handshake according to the protocol version the
* client announced
*/
switch (wsi->ws->ietf_spec_revision) {
default:
lwsl_notice("Unknown client spec version %d\n",
wsi->ws->ietf_spec_revision);
wsi->ws->ietf_spec_revision = 13;
//return 1;
/* fallthru */
case 13:
#if defined(LWS_WITH_HTTP2)
if (wsi->h2_stream_carries_ws) {
if (lws_h2_ws_handshake(wsi)) {
lwsl_notice("h2 ws handshake failed\n");
return 1;
}
} else
#endif
{
lwsl_parser("lws_parse calling handshake_04\n");
if (handshake_0405(wsi->context, wsi)) {
lwsl_notice("hs0405 has failed the connection\n");
return 1;
}
}
break;
}
lws_same_vh_protocol_insert(wsi, n);
/*
* We are upgrading to ws, so http/1.1 + h2 and keepalive + pipelined
* header considerations about keeping the ah around no longer apply.
*
* However it's common for the first ws protocol data to have been
* coalesced with the browser upgrade request and to already be in the
* ah rx buffer.
*/
lwsl_debug("%s: %p: inheriting ws ah (rxpos:%d, rxlen:%d)\n",
__func__, wsi, wsi->ah->rxpos, wsi->ah->rxlen);
lws_pt_lock(pt, __func__);
if (wsi->h2_stream_carries_ws)
lws_role_transition(wsi, LWSIFR_SERVER | LWSIFR_P_ENCAP_H2,
LRS_ESTABLISHED, &role_ops_ws);
else
lws_role_transition(wsi, LWSIFR_SERVER, LRS_ESTABLISHED,
&role_ops_ws);
/*
* Because rxpos/rxlen shows something in the ah, we will get
* service guaranteed next time around the event loop
*/
lws_pt_unlock(pt);
lws_server_init_wsi_for_ws(wsi);
lwsl_parser("accepted v%02d connection\n", wsi->ws->ietf_spec_revision);
/* !!! drop ah unreservedly after ESTABLISHED */
if (wsi->ah->rxpos == wsi->ah->rxlen) {
lwsl_info("%s: %p: dropping ah on ws upgrade\n", __func__, wsi);
lws_header_table_force_to_detachable_state(wsi);
lws_header_table_detach(wsi, 1);
} else
lwsl_info("%s: %p: unable to drop ah at ws upgrade %d vs %d\n",
__func__, wsi, wsi->ah->rxpos, wsi->ah->rxlen);
return 0;
}
int
handshake_0405(struct lws_context *context, struct lws *wsi)
{
struct lws_context_per_thread *pt = &context->pt[(int)wsi->tsi];
struct lws_process_html_args args;
unsigned char hash[20];
int n, accept_len;
char *response;
char *p;
if (!lws_hdr_total_length(wsi, WSI_TOKEN_HOST) ||
!lws_hdr_total_length(wsi, WSI_TOKEN_KEY)) {
lwsl_info("handshake_04 missing pieces\n");
/* completed header processing, but missing some bits */
goto bail;
}
if (lws_hdr_total_length(wsi, WSI_TOKEN_KEY) >= MAX_WEBSOCKET_04_KEY_LEN) {
lwsl_warn("Client key too long %d\n", MAX_WEBSOCKET_04_KEY_LEN);
goto bail;
}
/*
* since key length is restricted above (currently 128), cannot
* overflow
*/
n = sprintf((char *)pt->serv_buf,
"%s258EAFA5-E914-47DA-95CA-C5AB0DC85B11",
lws_hdr_simple_ptr(wsi, WSI_TOKEN_KEY));
lws_SHA1(pt->serv_buf, n, hash);
accept_len = lws_b64_encode_string((char *)hash, 20,
(char *)pt->serv_buf, context->pt_serv_buf_size);
if (accept_len < 0) {
lwsl_warn("Base64 encoded hash too long\n");
goto bail;
}
/* allocate the per-connection user memory (if any) */
if (lws_ensure_user_space(wsi))
goto bail;
/* create the response packet */
/* make a buffer big enough for everything */
response = (char *)pt->serv_buf + MAX_WEBSOCKET_04_KEY_LEN + LWS_PRE;
p = response;
LWS_CPYAPP(p, "HTTP/1.1 101 Switching Protocols\x0d\x0a"
"Upgrade: WebSocket\x0d\x0a"
"Connection: Upgrade\x0d\x0a"
"Sec-WebSocket-Accept: ");
strcpy(p, (char *)pt->serv_buf);
p += accept_len;
/* we can only return the protocol header if:
* - one came in, and ... */
if (lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL) &&
/* - it is not an empty string */
wsi->protocol->name &&
wsi->protocol->name[0]) {
LWS_CPYAPP(p, "\x0d\x0aSec-WebSocket-Protocol: ");
p += lws_snprintf(p, 128, "%s", wsi->protocol->name);
}
#if !defined(LWS_WITHOUT_EXTENSIONS)
/*
* Figure out which extensions the client has that we want to
* enable on this connection, and give him back the list.
*
* Give him a limited write bugdet
*/
if (lws_extension_server_handshake(wsi, &p, 192))
goto bail;
#endif
LWS_CPYAPP(p, "\x0d\x0a");
args.p = p;
args.max_len = lws_ptr_diff((char *)pt->serv_buf +
context->pt_serv_buf_size, p);
if (user_callback_handle_rxflow(wsi->protocol->callback, wsi,
LWS_CALLBACK_ADD_HEADERS,
wsi->user_space, &args, 0))
goto bail;
p = args.p;
/* end of response packet */
LWS_CPYAPP(p, "\x0d\x0a");
if (!lws_any_extension_handled(wsi, LWS_EXT_CB_HANDSHAKE_REPLY_TX,
response, p - response)) {
/* okay send the handshake response accepting the connection */
lwsl_parser("issuing resp pkt %d len\n",
lws_ptr_diff(p, response));
#if defined(DEBUG)
fwrite(response, 1, p - response, stderr);
#endif
n = lws_write(wsi, (unsigned char *)response, p - response,
LWS_WRITE_HTTP_HEADERS);
if (n != (p - response)) {
lwsl_info("%s: ERROR writing to socket %d\n", __func__, n);
goto bail;
}
}
/* alright clean up and set ourselves into established state */
lwsi_set_state(wsi, LRS_ESTABLISHED);
wsi->lws_rx_parse_state = LWS_RXPS_NEW;
{
const char * uri_ptr =
lws_hdr_simple_ptr(wsi, WSI_TOKEN_GET_URI);
int uri_len = lws_hdr_total_length(wsi, WSI_TOKEN_GET_URI);
const struct lws_http_mount *hit =
lws_find_mount(wsi, uri_ptr, uri_len);
if (hit && hit->cgienv &&
wsi->protocol->callback(wsi, LWS_CALLBACK_HTTP_PMO,
wsi->user_space, (void *)hit->cgienv, 0))
return 1;
}
return 0;
bail:
/* caller will free up his parsing allocations */
return -1;
}
int
lws_interpret_incoming_packet(struct lws *wsi, unsigned char **buf, size_t len)
{
int m, draining_flow = 0;
lwsl_parser("%s: received %d byte packet\n", __func__, (int)len);
/* let the rx protocol state machine have as much as it needs */
while (len) {
/*
* we were accepting input but now we stopped doing so
*/
if (wsi->rxflow_bitmap) {
lws_rxflow_cache(wsi, *buf, 0, (int)len);
lwsl_parser("%s: cached %ld\n", __func__, (long)len);
buf += len; /* stashing it is taking care of it */
return 1;
}
if (wsi->ws->rx_draining_ext) {
m = lws_ws_rx_sm(wsi, 0);
if (m < 0)
return -1;
continue;
}
/* account for what we're using in rxflow buffer */
if (lws_buflist_next_segment_len(&wsi->buflist_rxflow, NULL)) {
draining_flow = 1;
if (!lws_buflist_use_segment(&wsi->buflist_rxflow, 1))
lws_dll_lws_remove(&wsi->dll_rxflow);
}
/* consume payload bytes efficiently */
if (wsi->lws_rx_parse_state ==
LWS_RXPS_PAYLOAD_UNTIL_LENGTH_EXHAUSTED) {
m = lws_payload_until_length_exhausted(wsi, buf, &len);
if (lws_buflist_next_segment_len(&wsi->buflist_rxflow, NULL)) {
draining_flow = 1;
if (!lws_buflist_use_segment(&wsi->buflist_rxflow, m))
lws_dll_lws_remove(&wsi->dll_rxflow);
}
}
/* process the byte */
m = lws_ws_rx_sm(wsi, *(*buf)++);
if (m < 0)
return -1;
len--;
if (draining_flow && /* were draining, now nothing left */
!lws_buflist_next_segment_len(&wsi->buflist_rxflow, NULL)) {
lwsl_debug("%s: %p flow buf: drained\n", __func__, wsi);
/* having drained the rxflow buffer, can rearm POLLIN */
#ifdef LWS_NO_SERVER
m =
#endif
__lws_rx_flow_control(wsi);
/* m ignored, needed for NO_SERVER case */
}
}
lwsl_parser("%s: exit with %d unused\n", __func__, (int)len);
return 0;
}
Reference in a new issue View git blame Copy permalink