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bitcoin-bitcoin-core/src/httpserver.cpp
João Barbosa 6b13580f4e http: Unlisten sockets after all workers quit 
This (almost) move only ensures the event base loop doesn't exit before
HTTP worker threads exit. This way events registered by HTTP workers are
processed and not discarded.
2018-11-23 16:54:22 +00:00

686 lines
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// Copyright (c) 2015-2018 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <httpserver.h>
#include <chainparamsbase.h>
#include <compat.h>
#include <util/system.h>
#include <util/strencodings.h>
#include <netbase.h>
#include <rpc/protocol.h> // For HTTP status codes
#include <shutdown.h>
#include <sync.h>
#include <ui_interface.h>
#include <memory>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <future>
#include <event2/thread.h>
#include <event2/buffer.h>
#include <event2/bufferevent.h>
#include <event2/util.h>
#include <event2/keyvalq_struct.h>
#include <support/events.h>
#ifdef EVENT__HAVE_NETINET_IN_H
#include <netinet/in.h>
#ifdef _XOPEN_SOURCE_EXTENDED
#include <arpa/inet.h>
#endif
#endif
/** Maximum size of http request (request line + headers) */
static const size_t MAX_HEADERS_SIZE = 8192;
/** HTTP request work item */
class HTTPWorkItem final : public HTTPClosure
{
public:
HTTPWorkItem(std::unique_ptr<HTTPRequest> _req, const std::string &_path, const HTTPRequestHandler& _func):
req(std::move(_req)), path(_path), func(_func)
{
}
void operator()() override
{
func(req.get(), path);
}
std::unique_ptr<HTTPRequest> req;
private:
std::string path;
HTTPRequestHandler func;
};
/** Simple work queue for distributing work over multiple threads.
* Work items are simply callable objects.
*/
template <typename WorkItem>
class WorkQueue
{
private:
/** Mutex protects entire object */
Mutex cs;
std::condition_variable cond;
std::deque<std::unique_ptr<WorkItem>> queue;
bool running;
size_t maxDepth;
public:
explicit WorkQueue(size_t _maxDepth) : running(true),
maxDepth(_maxDepth)
{
}
/** Precondition: worker threads have all stopped (they have been joined).
*/
~WorkQueue()
{
}
/** Enqueue a work item */
bool Enqueue(WorkItem* item)
{
LOCK(cs);
if (queue.size() >= maxDepth) {
return false;
}
queue.emplace_back(std::unique_ptr<WorkItem>(item));
cond.notify_one();
return true;
}
/** Thread function */
void Run()
{
while (true) {
std::unique_ptr<WorkItem> i;
{
WAIT_LOCK(cs, lock);
while (running && queue.empty())
cond.wait(lock);
if (!running)
break;
i = std::move(queue.front());
queue.pop_front();
}
(*i)();
}
}
/** Interrupt and exit loops */
void Interrupt()
{
LOCK(cs);
running = false;
cond.notify_all();
}
};
struct HTTPPathHandler
{
HTTPPathHandler() {}
HTTPPathHandler(std::string _prefix, bool _exactMatch, HTTPRequestHandler _handler):
prefix(_prefix), exactMatch(_exactMatch), handler(_handler)
{
}
std::string prefix;
bool exactMatch;
HTTPRequestHandler handler;
};
/** HTTP module state */
//! libevent event loop
static struct event_base* eventBase = nullptr;
//! HTTP server
struct evhttp* eventHTTP = nullptr;
//! List of subnets to allow RPC connections from
static std::vector<CSubNet> rpc_allow_subnets;
//! Work queue for handling longer requests off the event loop thread
static WorkQueue<HTTPClosure>* workQueue = nullptr;
//! Handlers for (sub)paths
std::vector<HTTPPathHandler> pathHandlers;
//! Bound listening sockets
std::vector<evhttp_bound_socket *> boundSockets;
/** Check if a network address is allowed to access the HTTP server */
static bool ClientAllowed(const CNetAddr& netaddr)
{
if (!netaddr.IsValid())
return false;
for(const CSubNet& subnet : rpc_allow_subnets)
if (subnet.Match(netaddr))
return true;
return false;
}
/** Initialize ACL list for HTTP server */
static bool InitHTTPAllowList()
{
rpc_allow_subnets.clear();
CNetAddr localv4;
CNetAddr localv6;
LookupHost("127.0.0.1", localv4, false);
LookupHost("::1", localv6, false);
rpc_allow_subnets.push_back(CSubNet(localv4, 8)); // always allow IPv4 local subnet
rpc_allow_subnets.push_back(CSubNet(localv6)); // always allow IPv6 localhost
for (const std::string& strAllow : gArgs.GetArgs("-rpcallowip")) {
CSubNet subnet;
LookupSubNet(strAllow.c_str(), subnet);
if (!subnet.IsValid()) {
uiInterface.ThreadSafeMessageBox(
strprintf("Invalid -rpcallowip subnet specification: %s. Valid are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. 1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24).", strAllow),
"", CClientUIInterface::MSG_ERROR);
return false;
}
rpc_allow_subnets.push_back(subnet);
}
std::string strAllowed;
for (const CSubNet& subnet : rpc_allow_subnets)
strAllowed += subnet.ToString() + " ";
LogPrint(BCLog::HTTP, "Allowing HTTP connections from: %s\n", strAllowed);
return true;
}
/** HTTP request method as string - use for logging only */
static std::string RequestMethodString(HTTPRequest::RequestMethod m)
{
switch (m) {
case HTTPRequest::GET:
return "GET";
break;
case HTTPRequest::POST:
return "POST";
break;
case HTTPRequest::HEAD:
return "HEAD";
break;
case HTTPRequest::PUT:
return "PUT";
break;
default:
return "unknown";
}
}
/** HTTP request callback */
static void http_request_cb(struct evhttp_request* req, void* arg)
{
// Disable reading to work around a libevent bug, fixed in 2.2.0.
if (event_get_version_number() >= 0x02010600 && event_get_version_number() < 0x02020001) {
evhttp_connection* conn = evhttp_request_get_connection(req);
if (conn) {
bufferevent* bev = evhttp_connection_get_bufferevent(conn);
if (bev) {
bufferevent_disable(bev, EV_READ);
}
}
}
std::unique_ptr<HTTPRequest> hreq(new HTTPRequest(req));
// Early address-based allow check
if (!ClientAllowed(hreq->GetPeer())) {
LogPrint(BCLog::HTTP, "HTTP request from %s rejected: Client network is not allowed RPC access\n",
hreq->GetPeer().ToString());
hreq->WriteReply(HTTP_FORBIDDEN);
return;
}
// Early reject unknown HTTP methods
if (hreq->GetRequestMethod() == HTTPRequest::UNKNOWN) {
LogPrint(BCLog::HTTP, "HTTP request from %s rejected: Unknown HTTP request method\n",
hreq->GetPeer().ToString());
hreq->WriteReply(HTTP_BADMETHOD);
return;
}
LogPrint(BCLog::HTTP, "Received a %s request for %s from %s\n",
RequestMethodString(hreq->GetRequestMethod()), SanitizeString(hreq->GetURI(), SAFE_CHARS_URI).substr(0, 100), hreq->GetPeer().ToString());
// Find registered handler for prefix
std::string strURI = hreq->GetURI();
std::string path;
std::vector<HTTPPathHandler>::const_iterator i = pathHandlers.begin();
std::vector<HTTPPathHandler>::const_iterator iend = pathHandlers.end();
for (; i != iend; ++i) {
bool match = false;
if (i->exactMatch)
match = (strURI == i->prefix);
else
match = (strURI.substr(0, i->prefix.size()) == i->prefix);
if (match) {
path = strURI.substr(i->prefix.size());
break;
}
}
// Dispatch to worker thread
if (i != iend) {
std::unique_ptr<HTTPWorkItem> item(new HTTPWorkItem(std::move(hreq), path, i->handler));
assert(workQueue);
if (workQueue->Enqueue(item.get()))
item.release(); /* if true, queue took ownership */
else {
LogPrintf("WARNING: request rejected because http work queue depth exceeded, it can be increased with the -rpcworkqueue= setting\n");
item->req->WriteReply(HTTP_INTERNAL, "Work queue depth exceeded");
}
} else {
hreq->WriteReply(HTTP_NOTFOUND);
}
}
/** Callback to reject HTTP requests after shutdown. */
static void http_reject_request_cb(struct evhttp_request* req, void*)
{
LogPrint(BCLog::HTTP, "Rejecting request while shutting down\n");
evhttp_send_error(req, HTTP_SERVUNAVAIL, nullptr);
}
/** Event dispatcher thread */
static bool ThreadHTTP(struct event_base* base)
{
RenameThread("bitcoin-http");
LogPrint(BCLog::HTTP, "Entering http event loop\n");
event_base_dispatch(base);
// Event loop will be interrupted by InterruptHTTPServer()
LogPrint(BCLog::HTTP, "Exited http event loop\n");
return event_base_got_break(base) == 0;
}
/** Bind HTTP server to specified addresses */
static bool HTTPBindAddresses(struct evhttp* http)
{
int http_port = gArgs.GetArg("-rpcport", BaseParams().RPCPort());
std::vector<std::pair<std::string, uint16_t> > endpoints;
// Determine what addresses to bind to
if (!(gArgs.IsArgSet("-rpcallowip") && gArgs.IsArgSet("-rpcbind"))) { // Default to loopback if not allowing external IPs
endpoints.push_back(std::make_pair("::1", http_port));
endpoints.push_back(std::make_pair("127.0.0.1", http_port));
if (gArgs.IsArgSet("-rpcallowip")) {
LogPrintf("WARNING: option -rpcallowip was specified without -rpcbind; this doesn't usually make sense\n");
}
if (gArgs.IsArgSet("-rpcbind")) {
LogPrintf("WARNING: option -rpcbind was ignored because -rpcallowip was not specified, refusing to allow everyone to connect\n");
}
} else if (gArgs.IsArgSet("-rpcbind")) { // Specific bind address
for (const std::string& strRPCBind : gArgs.GetArgs("-rpcbind")) {
int port = http_port;
std::string host;
SplitHostPort(strRPCBind, port, host);
endpoints.push_back(std::make_pair(host, port));
}
}
// Bind addresses
for (std::vector<std::pair<std::string, uint16_t> >::iterator i = endpoints.begin(); i != endpoints.end(); ++i) {
LogPrint(BCLog::HTTP, "Binding RPC on address %s port %i\n", i->first, i->second);
evhttp_bound_socket *bind_handle = evhttp_bind_socket_with_handle(http, i->first.empty() ? nullptr : i->first.c_str(), i->second);
if (bind_handle) {
CNetAddr addr;
if (i->first.empty() || (LookupHost(i->first.c_str(), addr, false) && addr.IsBindAny())) {
LogPrintf("WARNING: the RPC server is not safe to expose to untrusted networks such as the public internet\n");
}
boundSockets.push_back(bind_handle);
} else {
LogPrintf("Binding RPC on address %s port %i failed.\n", i->first, i->second);
}
}
return !boundSockets.empty();
}
/** Simple wrapper to set thread name and run work queue */
static void HTTPWorkQueueRun(WorkQueue<HTTPClosure>* queue)
{
RenameThread("bitcoin-httpworker");
queue->Run();
}
/** libevent event log callback */
static void libevent_log_cb(int severity, const char *msg)
{
#ifndef EVENT_LOG_WARN
// EVENT_LOG_WARN was added in 2.0.19; but before then _EVENT_LOG_WARN existed.
# define EVENT_LOG_WARN _EVENT_LOG_WARN
#endif
if (severity >= EVENT_LOG_WARN) // Log warn messages and higher without debug category
LogPrintf("libevent: %s\n", msg);
else
LogPrint(BCLog::LIBEVENT, "libevent: %s\n", msg);
}
bool InitHTTPServer()
{
if (!InitHTTPAllowList())
return false;
// Redirect libevent's logging to our own log
event_set_log_callback(&libevent_log_cb);
// Update libevent's log handling. Returns false if our version of
// libevent doesn't support debug logging, in which case we should
// clear the BCLog::LIBEVENT flag.
if (!UpdateHTTPServerLogging(g_logger->WillLogCategory(BCLog::LIBEVENT))) {
g_logger->DisableCategory(BCLog::LIBEVENT);
}
#ifdef WIN32
evthread_use_windows_threads();
#else
evthread_use_pthreads();
#endif
raii_event_base base_ctr = obtain_event_base();
/* Create a new evhttp object to handle requests. */
raii_evhttp http_ctr = obtain_evhttp(base_ctr.get());
struct evhttp* http = http_ctr.get();
if (!http) {
LogPrintf("couldn't create evhttp. Exiting.\n");
return false;
}
evhttp_set_timeout(http, gArgs.GetArg("-rpcservertimeout", DEFAULT_HTTP_SERVER_TIMEOUT));
evhttp_set_max_headers_size(http, MAX_HEADERS_SIZE);
evhttp_set_max_body_size(http, MAX_SIZE);
evhttp_set_gencb(http, http_request_cb, nullptr);
if (!HTTPBindAddresses(http)) {
LogPrintf("Unable to bind any endpoint for RPC server\n");
return false;
}
LogPrint(BCLog::HTTP, "Initialized HTTP server\n");
int workQueueDepth = std::max((long)gArgs.GetArg("-rpcworkqueue", DEFAULT_HTTP_WORKQUEUE), 1L);
LogPrintf("HTTP: creating work queue of depth %d\n", workQueueDepth);
workQueue = new WorkQueue<HTTPClosure>(workQueueDepth);
// transfer ownership to eventBase/HTTP via .release()
eventBase = base_ctr.release();
eventHTTP = http_ctr.release();
return true;
}
bool UpdateHTTPServerLogging(bool enable) {
#if LIBEVENT_VERSION_NUMBER >= 0x02010100
if (enable) {
event_enable_debug_logging(EVENT_DBG_ALL);
} else {
event_enable_debug_logging(EVENT_DBG_NONE);
}
return true;
#else
// Can't update libevent logging if version < 02010100
return false;
#endif
}
std::thread threadHTTP;
std::future<bool> threadResult;
static std::vector<std::thread> g_thread_http_workers;
void StartHTTPServer()
{
LogPrint(BCLog::HTTP, "Starting HTTP server\n");
int rpcThreads = std::max((long)gArgs.GetArg("-rpcthreads", DEFAULT_HTTP_THREADS), 1L);
LogPrintf("HTTP: starting %d worker threads\n", rpcThreads);
std::packaged_task<bool(event_base*)> task(ThreadHTTP);
threadResult = task.get_future();
threadHTTP = std::thread(std::move(task), eventBase);
for (int i = 0; i < rpcThreads; i++) {
g_thread_http_workers.emplace_back(HTTPWorkQueueRun, workQueue);
}
}
void InterruptHTTPServer()
{
LogPrint(BCLog::HTTP, "Interrupting HTTP server\n");
if (eventHTTP) {
// Reject requests on current connections
evhttp_set_gencb(eventHTTP, http_reject_request_cb, nullptr);
}
if (workQueue)
workQueue->Interrupt();
}
void StopHTTPServer()
{
LogPrint(BCLog::HTTP, "Stopping HTTP server\n");
if (workQueue) {
LogPrint(BCLog::HTTP, "Waiting for HTTP worker threads to exit\n");
for (auto& thread: g_thread_http_workers) {
thread.join();
}
g_thread_http_workers.clear();
delete workQueue;
workQueue = nullptr;
}
// Unlisten sockets, these are what make the event loop running, which means
// that after this and all connections are closed the event loop will quit.
for (evhttp_bound_socket *socket : boundSockets) {
evhttp_del_accept_socket(eventHTTP, socket);
}
boundSockets.clear();
if (eventBase) {
LogPrint(BCLog::HTTP, "Waiting for HTTP event thread to exit\n");
// Exit the event loop as soon as there are no active events.
event_base_loopexit(eventBase, nullptr);
// Give event loop a few seconds to exit (to send back last RPC responses), then break it
// Before this was solved with event_base_loopexit, but that didn't work as expected in
// at least libevent 2.0.21 and always introduced a delay. In libevent
// master that appears to be solved, so in the future that solution
// could be used again (if desirable).
// (see discussion in https://github.com/bitcoin/bitcoin/pull/6990)
if (threadResult.valid() && threadResult.wait_for(std::chrono::milliseconds(2000)) == std::future_status::timeout) {
LogPrintf("HTTP event loop did not exit within allotted time, sending loopbreak\n");
event_base_loopbreak(eventBase);
}
threadHTTP.join();
}
if (eventHTTP) {
evhttp_free(eventHTTP);
eventHTTP = nullptr;
}
if (eventBase) {
event_base_free(eventBase);
eventBase = nullptr;
}
LogPrint(BCLog::HTTP, "Stopped HTTP server\n");
}
struct event_base* EventBase()
{
return eventBase;
}
static void httpevent_callback_fn(evutil_socket_t, short, void* data)
{
// Static handler: simply call inner handler
HTTPEvent *self = static_cast<HTTPEvent*>(data);
self->handler();
if (self->deleteWhenTriggered)
delete self;
}
HTTPEvent::HTTPEvent(struct event_base* base, bool _deleteWhenTriggered, const std::function<void()>& _handler):
deleteWhenTriggered(_deleteWhenTriggered), handler(_handler)
{
ev = event_new(base, -1, 0, httpevent_callback_fn, this);
assert(ev);
}
HTTPEvent::~HTTPEvent()
{
event_free(ev);
}
void HTTPEvent::trigger(struct timeval* tv)
{
if (tv == nullptr)
event_active(ev, 0, 0); // immediately trigger event in main thread
else
evtimer_add(ev, tv); // trigger after timeval passed
}
HTTPRequest::HTTPRequest(struct evhttp_request* _req) : req(_req),
replySent(false)
{
}
HTTPRequest::~HTTPRequest()
{
if (!replySent) {
// Keep track of whether reply was sent to avoid request leaks
LogPrintf("%s: Unhandled request\n", __func__);
WriteReply(HTTP_INTERNAL, "Unhandled request");
}
// evhttpd cleans up the request, as long as a reply was sent.
}
std::pair<bool, std::string> HTTPRequest::GetHeader(const std::string& hdr) const
{
const struct evkeyvalq* headers = evhttp_request_get_input_headers(req);
assert(headers);
const char* val = evhttp_find_header(headers, hdr.c_str());
if (val)
return std::make_pair(true, val);
else
return std::make_pair(false, "");
}
std::string HTTPRequest::ReadBody()
{
struct evbuffer* buf = evhttp_request_get_input_buffer(req);
if (!buf)
return "";
size_t size = evbuffer_get_length(buf);
/** Trivial implementation: if this is ever a performance bottleneck,
* internal copying can be avoided in multi-segment buffers by using
* evbuffer_peek and an awkward loop. Though in that case, it'd be even
* better to not copy into an intermediate string but use a stream
* abstraction to consume the evbuffer on the fly in the parsing algorithm.
*/
const char* data = (const char*)evbuffer_pullup(buf, size);
if (!data) // returns nullptr in case of empty buffer
return "";
std::string rv(data, size);
evbuffer_drain(buf, size);
return rv;
}
void HTTPRequest::WriteHeader(const std::string& hdr, const std::string& value)
{
struct evkeyvalq* headers = evhttp_request_get_output_headers(req);
assert(headers);
evhttp_add_header(headers, hdr.c_str(), value.c_str());
}
/** Closure sent to main thread to request a reply to be sent to
* a HTTP request.
* Replies must be sent in the main loop in the main http thread,
* this cannot be done from worker threads.
*/
void HTTPRequest::WriteReply(int nStatus, const std::string& strReply)
{
assert(!replySent && req);
if (ShutdownRequested()) {
WriteHeader("Connection", "close");
}
// Send event to main http thread to send reply message
struct evbuffer* evb = evhttp_request_get_output_buffer(req);
assert(evb);
evbuffer_add(evb, strReply.data(), strReply.size());
auto req_copy = req;
HTTPEvent* ev = new HTTPEvent(eventBase, true, [req_copy, nStatus]{
evhttp_send_reply(req_copy, nStatus, nullptr, nullptr);
// Re-enable reading from the socket. This is the second part of the libevent
// workaround above.
if (event_get_version_number() >= 0x02010600 && event_get_version_number() < 0x02020001) {
evhttp_connection* conn = evhttp_request_get_connection(req_copy);
if (conn) {
bufferevent* bev = evhttp_connection_get_bufferevent(conn);
if (bev) {
bufferevent_enable(bev, EV_READ | EV_WRITE);
}
}
}
});
ev->trigger(nullptr);
replySent = true;
req = nullptr; // transferred back to main thread
}
CService HTTPRequest::GetPeer() const
{
evhttp_connection* con = evhttp_request_get_connection(req);
CService peer;
if (con) {
// evhttp retains ownership over returned address string
const char* address = "";
uint16_t port = 0;
evhttp_connection_get_peer(con, (char**)&address, &port);
peer = LookupNumeric(address, port);
}
return peer;
}
std::string HTTPRequest::GetURI() const
{
return evhttp_request_get_uri(req);
}
HTTPRequest::RequestMethod HTTPRequest::GetRequestMethod() const
{
switch (evhttp_request_get_command(req)) {
case EVHTTP_REQ_GET:
return GET;
break;
case EVHTTP_REQ_POST:
return POST;
break;
case EVHTTP_REQ_HEAD:
return HEAD;
break;
case EVHTTP_REQ_PUT:
return PUT;
break;
default:
return UNKNOWN;
break;
}
}
void RegisterHTTPHandler(const std::string &prefix, bool exactMatch, const HTTPRequestHandler &handler)
{
LogPrint(BCLog::HTTP, "Registering HTTP handler for %s (exactmatch %d)\n", prefix, exactMatch);
pathHandlers.push_back(HTTPPathHandler(prefix, exactMatch, handler));
}
void UnregisterHTTPHandler(const std::string &prefix, bool exactMatch)
{
std::vector<HTTPPathHandler>::iterator i = pathHandlers.begin();
std::vector<HTTPPathHandler>::iterator iend = pathHandlers.end();
for (; i != iend; ++i)
if (i->prefix == prefix && i->exactMatch == exactMatch)
break;
if (i != iend)
{
LogPrint(BCLog::HTTP, "Unregistering HTTP handler for %s (exactmatch %d)\n", prefix, exactMatch);
pathHandlers.erase(i);
}
}
std::string urlDecode(const std::string &urlEncoded) {
std::string res;
if (!urlEncoded.empty()) {
char *decoded = evhttp_uridecode(urlEncoded.c_str(), false, nullptr);
if (decoded) {
res = std::string(decoded);
free(decoded);
}
}
return res;
}
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