transmission/libtransmission/web.cc

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/*
* This file Copyright (C) 2008-2014 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#include <algorithm>
#include <cstring>
#include <set>
#include <string>
#include <string_view>
#ifdef _WIN32
#include <windows.h>
#include <wincrypt.h>
#endif
#include <curl/curl.h>
#include <event2/buffer.h>
#include "transmission.h"
#include "crypto-utils.h"
#include "file.h"
#include "log.h"
#include "net.h" /* tr_address */
#include "torrent.h"
#include "platform.h" /* mutex */
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#include "session.h"
#include "tr-assert.h"
#include "tr-macros.h"
#include "trevent.h" /* tr_runInEventThread() */
#include "utils.h"
#include "version.h" /* User-Agent */
#include "web.h"
using namespace std::literals;
#if LIBCURL_VERSION_NUM >= 0x070F06 /* CURLOPT_SOCKOPT* was added in 7.15.6 */
#define USE_LIBCURL_SOCKOPT
#endif
static auto constexpr ThreadfuncMaxSleepMsec = int{ 200 };
#define dbgmsg(...) tr_logAddDeepNamed("web", __VA_ARGS__)
/***
****
***/
struct tr_web_task
{
std::string cookies;
std::string range;
std::string url;
CURL* curl_easy = nullptr;
evbuffer* freebuf = nullptr;
evbuffer* response = nullptr;
tr_session* session = nullptr;
tr_web_done_func done_func = nullptr;
tr_web_task* next = nullptr;
void* done_func_user_data = nullptr;
long code = 0;
long timeout_secs = 0;
int torrentId = 0;
bool did_connect = false;
bool did_timeout = false;
};
static void task_free(struct tr_web_task* task)
{
if (task->freebuf != nullptr)
{
evbuffer_free(task->freebuf);
}
delete task;
}
/***
****
***/
struct tr_web
{
bool curl_verbose;
bool curl_ssl_verify;
char* curl_ca_bundle;
int close_mode;
std::recursive_mutex web_tasks_mutex;
struct tr_web_task* tasks;
char* cookie_filename;
std::set<CURL*> paused_easy_handles;
};
/***
****
***/
static size_t writeFunc(void* ptr, size_t size, size_t nmemb, void* vtask)
{
size_t const byteCount = size * nmemb;
auto* task = static_cast<struct tr_web_task*>(vtask);
/* webseed downloads should be speed limited */
if (task->torrentId != -1)
{
tr_torrent const* const tor = tr_torrentFindFromId(task->session, task->torrentId);
if (tor != nullptr && tor->bandwidth->clamp(TR_DOWN, nmemb) == 0)
{
task->session->web->paused_easy_handles.insert(task->curl_easy);
return CURL_WRITEFUNC_PAUSE;
}
}
evbuffer_add(task->response, ptr, byteCount);
dbgmsg("wrote %zu bytes to task %p's buffer", byteCount, (void*)task);
return byteCount;
}
#ifdef USE_LIBCURL_SOCKOPT
static int sockoptfunction(void* vtask, curl_socket_t fd, curlsocktype /*purpose*/)
{
auto* task = static_cast<struct tr_web_task*>(vtask);
/* announce and scrape requests have tiny payloads. */
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if (auto const is_scrape = tr_strvContains(task->url, "scrape"sv), is_announce = tr_strvContains(task->url, "announce"sv);
is_scrape || is_announce)
{
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int const sndbuf = is_scrape ? 4096 : 1024;
int const rcvbuf = is_scrape ? 4096 : 3072;
/* ignore the sockopt() return values -- these are suggestions
rather than hard requirements & it's OK for them to fail */
(void)setsockopt(fd, SOL_SOCKET, SO_SNDBUF, reinterpret_cast<char const*>(&sndbuf), sizeof(sndbuf));
(void)setsockopt(fd, SOL_SOCKET, SO_RCVBUF, reinterpret_cast<char const*>(&rcvbuf), sizeof(rcvbuf));
}
/* return nonzero if this function encountered an error */
return 0;
}
#endif
static CURLcode ssl_context_func(CURL* /*curl*/, void* ssl_ctx, void* /*user_data*/)
{
tr_x509_store_t const cert_store = tr_ssl_get_x509_store(ssl_ctx);
if (cert_store == nullptr)
{
return CURLE_OK;
}
#ifdef _WIN32
curl_version_info_data const* const curl_ver = curl_version_info(CURLVERSION_NOW);
if (curl_ver->age >= 0 && strncmp(curl_ver->ssl_version, "Schannel", 8) == 0)
{
return CURLE_OK;
}
static LPCWSTR const sys_store_names[] = {
L"CA",
L"ROOT",
};
for (size_t i = 0; i < TR_N_ELEMENTS(sys_store_names); ++i)
{
HCERTSTORE const sys_cert_store = CertOpenSystemStoreW(0, sys_store_names[i]);
if (sys_cert_store == nullptr)
{
continue;
}
PCCERT_CONTEXT sys_cert = nullptr;
while (true)
{
sys_cert = CertFindCertificateInStore(sys_cert_store, X509_ASN_ENCODING, 0, CERT_FIND_ANY, nullptr, sys_cert);
if (sys_cert == nullptr)
{
break;
}
tr_x509_cert_t const cert = tr_x509_cert_new(sys_cert->pbCertEncoded, sys_cert->cbCertEncoded);
if (cert == nullptr)
{
continue;
}
tr_x509_store_add(cert_store, cert);
tr_x509_cert_free(cert);
}
CertCloseStore(sys_cert_store, 0);
}
#endif
return CURLE_OK;
}
static long getTimeoutFromURL(struct tr_web_task const* task)
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{
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if (auto const* const session = task->session; session == nullptr || session->isClosed)
{
return 20L;
}
if (tr_strvContains(task->url, "scrape"sv))
{
return 30L;
}
if (tr_strvContains(task->url, "announce"sv))
{
return 90L;
}
return 240L;
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}
static CURL* createEasy(tr_session* s, struct tr_web* web, struct tr_web_task* task)
{
CURL* const e = curl_easy_init();
task->curl_easy = e;
task->timeout_secs = getTimeoutFromURL(task);
curl_easy_setopt(e, CURLOPT_AUTOREFERER, 1L);
curl_easy_setopt(e, CURLOPT_ENCODING, "");
curl_easy_setopt(e, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(e, CURLOPT_MAXREDIRS, -1L);
curl_easy_setopt(e, CURLOPT_NOSIGNAL, 1L);
curl_easy_setopt(e, CURLOPT_PRIVATE, task);
#ifdef USE_LIBCURL_SOCKOPT
curl_easy_setopt(e, CURLOPT_SOCKOPTFUNCTION, sockoptfunction);
curl_easy_setopt(e, CURLOPT_SOCKOPTDATA, task);
#endif
if (web->curl_ssl_verify)
{
if (web->curl_ca_bundle != nullptr)
{
curl_easy_setopt(e, CURLOPT_CAINFO, web->curl_ca_bundle);
}
else
{
curl_easy_setopt(e, CURLOPT_SSL_CTX_FUNCTION, ssl_context_func);
}
}
else
{
curl_easy_setopt(e, CURLOPT_SSL_VERIFYHOST, 0L);
curl_easy_setopt(e, CURLOPT_SSL_VERIFYPEER, 0L);
}
curl_easy_setopt(e, CURLOPT_TIMEOUT, task->timeout_secs);
curl_easy_setopt(e, CURLOPT_URL, task->url.c_str());
curl_easy_setopt(e, CURLOPT_USERAGENT, TR_NAME "/" SHORT_VERSION_STRING);
curl_easy_setopt(e, CURLOPT_VERBOSE, (long)(web->curl_verbose ? 1 : 0));
curl_easy_setopt(e, CURLOPT_WRITEDATA, task);
curl_easy_setopt(e, CURLOPT_WRITEFUNCTION, writeFunc);
auto is_default_value = bool{};
tr_address const* addr = tr_sessionGetPublicAddress(s, TR_AF_INET, &is_default_value);
if (addr != nullptr && !is_default_value)
{
(void)curl_easy_setopt(e, CURLOPT_INTERFACE, tr_address_to_string(addr));
}
addr = tr_sessionGetPublicAddress(s, TR_AF_INET6, &is_default_value);
if (addr != nullptr && !is_default_value)
{
(void)curl_easy_setopt(e, CURLOPT_INTERFACE, tr_address_to_string(addr));
}
if (!std::empty(task->cookies))
{
(void)curl_easy_setopt(e, CURLOPT_COOKIE, task->cookies.c_str());
}
if (web->cookie_filename != nullptr)
{
(void)curl_easy_setopt(e, CURLOPT_COOKIEFILE, web->cookie_filename);
}
if (!std::empty(task->range))
{
curl_easy_setopt(e, CURLOPT_RANGE, task->range.c_str());
/* don't bother asking the server to compress webseed fragments */
curl_easy_setopt(e, CURLOPT_ENCODING, "identity");
}
return e;
}
/***
****
***/
static void task_finish_func(void* vtask)
{
auto* task = static_cast<struct tr_web_task*>(vtask);
dbgmsg("finished web task %p; got %ld", (void*)task, task->code);
if (task->done_func != nullptr)
{
auto const sv = std::string_view{ reinterpret_cast<char const*>(evbuffer_pullup(task->response, -1)),
evbuffer_get_length(task->response) };
(*task->done_func)(task->session, task->did_connect, task->did_timeout, task->code, sv, task->done_func_user_data);
}
task_free(task);
}
/****
*****
****/
static void tr_webThreadFunc(void* vsession);
static struct tr_web_task* tr_webRunImpl(
tr_session* session,
int torrentId,
std::string_view url,
std::string_view range,
std::string_view cookies,
tr_web_done_func done_func,
void* done_func_user_data,
struct evbuffer* buffer)
{
struct tr_web_task* task = nullptr;
if (!session->isClosing())
{
if (session->web == nullptr)
{
tr_threadNew(tr_webThreadFunc, session);
while (session->web == nullptr)
{
tr_wait_msec(20);
}
}
task = new tr_web_task{};
task->session = session;
task->torrentId = torrentId;
task->url = url;
task->range = range;
task->cookies = cookies;
task->done_func = done_func;
task->done_func_user_data = done_func_user_data;
task->response = buffer != nullptr ? buffer : evbuffer_new();
task->freebuf = buffer != nullptr ? nullptr : task->response;
auto const lock = std::unique_lock(session->web->web_tasks_mutex);
task->next = session->web->tasks;
session->web->tasks = task;
}
return task;
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}
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struct tr_web_task* tr_webRunWithCookies(
tr_session* session,
std::string_view url,
std::string_view cookies,
tr_web_done_func done_func,
void* done_func_user_data)
{
return tr_webRunImpl(session, -1, url, {}, cookies, done_func, done_func_user_data, nullptr);
}
struct tr_web_task* tr_webRun(tr_session* session, std::string_view url, tr_web_done_func done_func, void* done_func_user_data)
{
return tr_webRunWithCookies(session, url, {}, done_func, done_func_user_data);
}
struct tr_web_task* tr_webRunWebseed(
tr_torrent* tor,
std::string_view url,
std::string_view range,
tr_web_done_func done_func,
void* done_func_user_data,
struct evbuffer* buffer)
{
return tr_webRunImpl(tor->session, tr_torrentId(tor), url, range, {}, done_func, done_func_user_data, buffer);
}
static void tr_webThreadFunc(void* vsession)
{
auto* session = static_cast<tr_session*>(vsession);
/* try to enable ssl for https support; but if that fails,
* try a plain vanilla init */
if (curl_global_init(CURL_GLOBAL_SSL) != CURLE_OK)
{
curl_global_init(0);
}
auto* web = new tr_web{};
web->close_mode = ~0;
web->tasks = nullptr;
web->curl_verbose = tr_env_key_exists("TR_CURL_VERBOSE");
web->curl_ssl_verify = !tr_env_key_exists("TR_CURL_SSL_NO_VERIFY");
web->curl_ca_bundle = tr_env_get_string("CURL_CA_BUNDLE", nullptr);
if (web->curl_ssl_verify)
{
tr_logAddNamedInfo(
"web",
"will verify tracker certs using envvar CURL_CA_BUNDLE: %s",
web->curl_ca_bundle == nullptr ? "none" : web->curl_ca_bundle);
tr_logAddNamedInfo("web", "NB: this only works if you built against libcurl with openssl or gnutls, NOT nss");
tr_logAddNamedInfo("web", "NB: invalid certs will show up as 'Could not connect to tracker' like many other errors");
}
auto const str = tr_strvPath(session->config_dir, "cookies.txt");
if (tr_sys_path_exists(str.c_str(), nullptr))
{
web->cookie_filename = tr_strvDup(str);
}
auto* const multi = curl_multi_init();
session->web = web;
auto repeats = uint32_t{};
for (;;)
{
if (web->close_mode == TR_WEB_CLOSE_NOW)
{
break;
}
if (web->close_mode == TR_WEB_CLOSE_WHEN_IDLE && web->tasks == nullptr)
{
break;
}
/* add tasks from the queue */
{
auto const lock = std::unique_lock(web->web_tasks_mutex);
while (web->tasks != nullptr)
{
/* pop the task */
struct tr_web_task* task = web->tasks;
web->tasks = task->next;
task->next = nullptr;
dbgmsg("adding task to curl: [%s]", task->url.c_str());
curl_multi_add_handle(multi, createEasy(session, web, task));
}
}
/* resume any paused curl handles.
swap paused_easy_handles to prevent oscillation
between writeFunc this while loop */
auto paused = decltype(web->paused_easy_handles){};
std::swap(paused, web->paused_easy_handles);
std::for_each(std::begin(paused), std::end(paused), [](auto* curl) { curl_easy_pause(curl, CURLPAUSE_CONT); });
/* maybe wait a little while before calling curl_multi_perform() */
auto msec = long{};
curl_multi_timeout(multi, &msec);
if (msec < 0)
{
msec = ThreadfuncMaxSleepMsec;
}
if (session->isClosed)
{
msec = 100; /* on shutdown, call perform() more frequently */
}
if (msec > 0)
{
if (msec > ThreadfuncMaxSleepMsec)
{
msec = ThreadfuncMaxSleepMsec;
}
auto numfds = int{};
curl_multi_wait(multi, nullptr, 0, msec, &numfds);
if (!numfds)
{
repeats++;
if (repeats > 1)
{
/* curl_multi_wait() returns immediately if there are
* no fds to wait for, so we need an explicit wait here
* to emulate select() behavior */
tr_wait_msec(std::min(msec, ThreadfuncMaxSleepMsec / 2L));
}
}
else
{
repeats = 0;
}
}
/* call curl_multi_perform() */
auto mcode = CURLMcode{};
auto unused = int{};
do
{
mcode = curl_multi_perform(multi, &unused);
} while (mcode == CURLM_CALL_MULTI_PERFORM);
/* pump completed tasks from the multi */
CURLMsg* msg = nullptr;
while ((msg = curl_multi_info_read(multi, &unused)) != nullptr)
{
if (msg->msg == CURLMSG_DONE && msg->easy_handle != nullptr)
{
CURL* const e = msg->easy_handle;
struct tr_web_task* task = nullptr;
curl_easy_getinfo(e, CURLINFO_PRIVATE, (void*)&task);
TR_ASSERT(e == task->curl_easy);
auto req_bytes_sent = long{};
auto total_time = double{};
curl_easy_getinfo(e, CURLINFO_RESPONSE_CODE, &task->code);
curl_easy_getinfo(e, CURLINFO_REQUEST_SIZE, &req_bytes_sent);
curl_easy_getinfo(e, CURLINFO_TOTAL_TIME, &total_time);
task->did_connect = task->code > 0 || req_bytes_sent > 0;
task->did_timeout = task->code == 0 && total_time >= task->timeout_secs;
curl_multi_remove_handle(multi, e);
web->paused_easy_handles.erase(e);
curl_easy_cleanup(e);
tr_runInEventThread(task->session, task_finish_func, task);
}
}
}
/* Discard any remaining tasks.
* This is rare, but can happen on shutdown with unresponsive trackers. */
while (web->tasks != nullptr)
{
struct tr_web_task* task = web->tasks;
web->tasks = task->next;
dbgmsg("Discarding task \"%s\"", task->url.c_str());
task_free(task);
}
/* cleanup */
curl_multi_cleanup(multi);
tr_free(web->curl_ca_bundle);
tr_free(web->cookie_filename);
delete web;
session->web = nullptr;
}
void tr_webClose(tr_session* session, tr_web_close_mode close_mode)
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{
if (session->web != nullptr)
{
session->web->close_mode = close_mode;
if (close_mode == TR_WEB_CLOSE_NOW)
{
while (session->web != nullptr)
{
tr_wait_msec(100);
}
}
}
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}
long tr_webGetTaskResponseCode(struct tr_web_task* task)
{
long code = 0;
curl_easy_getinfo(task->curl_easy, CURLINFO_RESPONSE_CODE, &code);
return code;
}
char const* tr_webGetTaskRealUrl(struct tr_web_task* task)
{
char* url = nullptr;
curl_easy_getinfo(task->curl_easy, CURLINFO_EFFECTIVE_URL, &url);
return url;
}