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transmission/libtransmission/web.c
Tavis Ormandy 440f03e9ad mitigate dns rebinding attacks against daemon
2018-01-16 01:12:56 +03:00

668 lines
19 KiB
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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.
*
* $Id$
*/
#include <assert.h>
#include <string.h> /* strlen (), strstr () */
#ifdef _WIN32
#include <ws2tcpip.h>
#else
#include <sys/select.h>
#endif
#include <curl/curl.h>
#include <event2/buffer.h>
#include "transmission.h"
#include "file.h"
#include "list.h"
#include "log.h"
#include "net.h" /* tr_address */
#include "torrent.h"
#include "platform.h" /* mutex */
#include "session.h"
#include "trevent.h" /* tr_runInEventThread () */
#include "utils.h"
#include "version.h" /* User-Agent */
#include "web.h"
#if LIBCURL_VERSION_NUM >= 0x070F06 /* CURLOPT_SOCKOPT* was added in 7.15.6 */
#define USE_LIBCURL_SOCKOPT
#endif
enum
{
THREADFUNC_MAX_SLEEP_MSEC = 200,
};
#if 0
#define dbgmsg(...) \
do { \
fprintf (stderr, __VA_ARGS__); \
fprintf (stderr, "\n"); \
} while (0)
#else
#define dbgmsg(...) \
do { \
if (tr_logGetDeepEnabled ()) \
tr_logAddDeep (__FILE__, __LINE__, "web", __VA_ARGS__); \
} while (0)
#endif
/***
****
***/
struct tr_web_task
{
int torrentId;
long code;
long timeout_secs;
bool did_connect;
bool did_timeout;
struct evbuffer * response;
struct evbuffer * freebuf;
char * url;
char * range;
char * cookies;
tr_session * session;
tr_web_done_func done_func;
void * done_func_user_data;
CURL * curl_easy;
struct tr_web_task * next;
};
static void
task_free (struct tr_web_task * task)
{
if (task->freebuf)
evbuffer_free (task->freebuf);
tr_free (task->cookies);
tr_free (task->range);
tr_free (task->url);
tr_free (task);
}
/***
****
***/
static tr_list * paused_easy_handles = NULL;
struct tr_web
{
bool curl_verbose;
bool curl_ssl_verify;
char * curl_ca_bundle;
int close_mode;
struct tr_web_task * tasks;
tr_lock * taskLock;
char * cookie_filename;
};
/***
****
***/
static size_t
writeFunc (void * ptr, size_t size, size_t nmemb, void * vtask)
{
const size_t byteCount = size * nmemb;
struct tr_web_task * task = vtask;
/* webseed downloads should be speed limited */
if (task->torrentId != -1)
{
tr_torrent * tor = tr_torrentFindFromId (task->session, task->torrentId);
if (tor && !tr_bandwidthClamp (&tor->bandwidth, TR_DOWN, nmemb))
{
tr_list_append (&paused_easy_handles, 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 UNUSED)
{
struct tr_web_task * task = vtask;
const bool isScrape = strstr (task->url, "scrape") != NULL;
const bool isAnnounce = strstr (task->url, "announce") != NULL;
/* announce and scrape requests have tiny payloads. */
if (isScrape || isAnnounce)
{
const int sndbuf = isScrape ? 4096 : 1024;
const int rcvbuf = isScrape ? 4096 : 3072;
setsockopt (fd, SOL_SOCKET, SO_SNDBUF, (const void *) &sndbuf, sizeof (sndbuf));
setsockopt (fd, SOL_SOCKET, SO_RCVBUF, (const void *) &rcvbuf, sizeof (rcvbuf));
}
/* return nonzero if this function encountered an error */
return 0;
}
#endif
static long
getTimeoutFromURL (const struct tr_web_task * task)
{
long timeout;
const tr_session * session = task->session;
if (!session || session->isClosed) timeout = 20L;
else if (strstr (task->url, "scrape") != NULL) timeout = 30L;
else if (strstr (task->url, "announce") != NULL) timeout = 90L;
else timeout = 240L;
return timeout;
}
static CURL *
createEasy (tr_session * s, struct tr_web * web, struct tr_web_task * task)
{
bool is_default_value;
const tr_address * addr;
CURL * e = task->curl_easy = curl_easy_init ();
task->timeout_secs = getTimeoutFromURL (task);
curl_easy_setopt (e, CURLOPT_AUTOREFERER, 1L);
curl_easy_setopt (e, CURLOPT_ENCODING, "gzip;q=1.0, deflate, identity");
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)
{
curl_easy_setopt (e, CURLOPT_CAINFO, web->curl_ca_bundle);
}
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);
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);
if (((addr = tr_sessionGetPublicAddress (s, TR_AF_INET, &is_default_value))) && !is_default_value)
curl_easy_setopt (e, CURLOPT_INTERFACE, tr_address_to_string (addr));
else if (((addr = tr_sessionGetPublicAddress (s, TR_AF_INET6, &is_default_value))) && !is_default_value)
curl_easy_setopt (e, CURLOPT_INTERFACE, tr_address_to_string (addr));
if (task->cookies != NULL)
curl_easy_setopt (e, CURLOPT_COOKIE, task->cookies);
if (web->cookie_filename != NULL)
curl_easy_setopt (e, CURLOPT_COOKIEFILE, web->cookie_filename);
if (task->range != NULL)
{
curl_easy_setopt (e, CURLOPT_RANGE, task->range);
/* 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)
{
struct tr_web_task * task = vtask;
dbgmsg ("finished web task %p; got %ld", (void*)task, task->code);
if (task->done_func != NULL)
task->done_func (task->session,
task->did_connect,
task->did_timeout,
task->code,
evbuffer_pullup (task->response, -1),
evbuffer_get_length (task->response),
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,
const char * url,
const char * range,
const char * cookies,
tr_web_done_func done_func,
void * done_func_user_data,
struct evbuffer * buffer)
{
struct tr_web_task * task = NULL;
if (!session->isClosing)
{
if (session->web == NULL)
{
tr_threadNew (tr_webThreadFunc, session);
while (session->web == NULL)
tr_wait_msec (20);
}
task = tr_new0 (struct tr_web_task, 1);
task->session = session;
task->torrentId = torrentId;
task->url = tr_strdup (url);
task->range = tr_strdup (range);
task->cookies = tr_strdup (cookies);
task->done_func = done_func;
task->done_func_user_data = done_func_user_data;
task->response = buffer ? buffer : evbuffer_new ();
task->freebuf = buffer ? NULL : task->response;
tr_lockLock (session->web->taskLock);
task->next = session->web->tasks;
session->web->tasks = task;
tr_lockUnlock (session->web->taskLock);
}
return task;
}
struct tr_web_task *
tr_webRunWithCookies (tr_session * session,
const char * url,
const char * cookies,
tr_web_done_func done_func,
void * done_func_user_data)
{
return tr_webRunImpl (session, -1, url,
NULL, cookies,
done_func, done_func_user_data,
NULL);
}
struct tr_web_task *
tr_webRun (tr_session * session,
const char * url,
tr_web_done_func done_func,
void * done_func_user_data)
{
return tr_webRunWithCookies (session, url, NULL,
done_func, done_func_user_data);
}
struct tr_web_task *
tr_webRunWebseed (tr_torrent * tor,
const char * url,
const char * 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, NULL,
done_func, done_func_user_data,
buffer);
}
/**
* Portability wrapper for select ().
*
* http://msdn.microsoft.com/en-us/library/ms740141%28VS.85%29.aspx
* On win32, any two of the parameters, readfds, writefds, or exceptfds,
* can be given as null. At least one must be non-null, and any non-null
* descriptor set must contain at least one handle to a socket.
*/
static void
tr_select (int nfds,
fd_set * r_fd_set, fd_set * w_fd_set, fd_set * c_fd_set,
struct timeval * t)
{
#ifdef _WIN32
(void) nfds;
if (!r_fd_set->fd_count && !w_fd_set->fd_count && !c_fd_set->fd_count)
{
const long int msec = t->tv_sec*1000 + t->tv_usec/1000;
tr_wait_msec (msec);
}
else if (select (0, r_fd_set->fd_count ? r_fd_set : NULL,
w_fd_set->fd_count ? w_fd_set : NULL,
c_fd_set->fd_count ? c_fd_set : NULL, t) < 0)
{
char errstr[512];
const int e = EVUTIL_SOCKET_ERROR ();
tr_net_strerror (errstr, sizeof (errstr), e);
dbgmsg ("Error: select (%d) %s", e, errstr);
}
#else
select (nfds, r_fd_set, w_fd_set, c_fd_set, t);
#endif
}
static void
tr_webThreadFunc (void * vsession)
{
char * str;
CURLM * multi;
struct tr_web * web;
int taskCount = 0;
struct tr_web_task * task;
tr_session * 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))
curl_global_init (0);
web = tr_new0 (struct tr_web, 1);
web->close_mode = ~0;
web->taskLock = tr_lockNew ();
web->tasks = NULL;
web->curl_verbose = tr_env_key_exists ("TR_CURL_VERBOSE");
web->curl_ssl_verify = tr_env_key_exists ("TR_CURL_SSL_VERIFY");
web->curl_ca_bundle = tr_env_get_string ("CURL_CA_BUNDLE", NULL);
if (web->curl_ssl_verify)
{
tr_logAddNamedInfo ("web", "will verify tracker certs using envvar CURL_CA_BUNDLE: %s",
web->curl_ca_bundle == NULL ? "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");
}
str = tr_buildPath (session->configDir, "cookies.txt", NULL);
if (tr_sys_path_exists (str, NULL))
web->cookie_filename = tr_strdup (str);
tr_free (str);
multi = curl_multi_init ();
session->web = web;
for (;;)
{
long msec;
int unused;
CURLMsg * msg;
CURLMcode mcode;
if (web->close_mode == TR_WEB_CLOSE_NOW)
break;
if ((web->close_mode == TR_WEB_CLOSE_WHEN_IDLE) && (web->tasks == NULL))
break;
/* add tasks from the queue */
tr_lockLock (web->taskLock);
while (web->tasks != NULL)
{
/* pop the task */
task = web->tasks;
web->tasks = task->next;
task->next = NULL;
dbgmsg ("adding task to curl: [%s]", task->url);
curl_multi_add_handle (multi, createEasy (session, web, task));
/*fprintf (stderr, "adding a task.. taskCount is now %d\n", taskCount);*/
++taskCount;
}
tr_lockUnlock (web->taskLock);
/* unpause any paused curl handles */
if (paused_easy_handles != NULL)
{
CURL * handle;
tr_list * tmp;
/* swap paused_easy_handles to prevent oscillation
between writeFunc this while loop */
tmp = paused_easy_handles;
paused_easy_handles = NULL;
while ((handle = tr_list_pop_front (&tmp)))
curl_easy_pause (handle, CURLPAUSE_CONT);
}
/* maybe wait a little while before calling curl_multi_perform () */
msec = 0;
curl_multi_timeout (multi, &msec);
if (msec < 0)
msec = THREADFUNC_MAX_SLEEP_MSEC;
if (session->isClosed)
msec = 100; /* on shutdown, call perform () more frequently */
if (msec > 0)
{
int usec;
int max_fd;
struct timeval t;
fd_set r_fd_set, w_fd_set, c_fd_set;
max_fd = 0;
FD_ZERO (&r_fd_set);
FD_ZERO (&w_fd_set);
FD_ZERO (&c_fd_set);
curl_multi_fdset (multi, &r_fd_set, &w_fd_set, &c_fd_set, &max_fd);
if (msec > THREADFUNC_MAX_SLEEP_MSEC)
msec = THREADFUNC_MAX_SLEEP_MSEC;
usec = msec * 1000;
t.tv_sec = usec / 1000000;
t.tv_usec = usec % 1000000;
tr_select (max_fd+1, &r_fd_set, &w_fd_set, &c_fd_set, &t);
}
/* call curl_multi_perform () */
do
mcode = curl_multi_perform (multi, &unused);
while (mcode == CURLM_CALL_MULTI_PERFORM);
/* pump completed tasks from the multi */
while ((msg = curl_multi_info_read (multi, &unused)))
{
if ((msg->msg == CURLMSG_DONE) && (msg->easy_handle != NULL))
{
double total_time;
struct tr_web_task * task;
long req_bytes_sent;
CURL * e = msg->easy_handle;
curl_easy_getinfo (e, CURLINFO_PRIVATE, (void*)&task);
assert (e == task->curl_easy);
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 && (total_time >= task->timeout_secs);
curl_multi_remove_handle (multi, e);
tr_list_remove_data (&paused_easy_handles, e);
curl_easy_cleanup (e);
tr_runInEventThread (task->session, task_finish_func, task);
--taskCount;
}
}
}
/* Discard any remaining tasks.
* This is rare, but can happen on shutdown with unresponsive trackers. */
while (web->tasks != NULL)
{
task = web->tasks;
web->tasks = task->next;
dbgmsg ("Discarding task \"%s\"", task->url);
task_free (task);
}
/* cleanup */
tr_list_free (&paused_easy_handles, NULL);
curl_multi_cleanup (multi);
tr_lockFree (web->taskLock);
tr_free (web->curl_ca_bundle);
tr_free (web->cookie_filename);
tr_free (web);
session->web = NULL;
}
void
tr_webClose (tr_session * session, tr_web_close_mode close_mode)
{
if (session->web != NULL)
{
session->web->close_mode = close_mode;
if (close_mode == TR_WEB_CLOSE_NOW)
while (session->web != NULL)
tr_wait_msec (100);
}
}
void
tr_webGetTaskInfo (struct tr_web_task * task, tr_web_task_info info, void * dst)
{
curl_easy_getinfo (task->curl_easy, (CURLINFO) info, dst);
}
/*****
******
******
*****/
const char *
tr_webGetResponseStr (long code)
{
switch (code)
{
case 0: return "No Response";
case 101: return "Switching Protocols";
case 200: return "OK";
case 201: return "Created";
case 202: return "Accepted";
case 203: return "Non-Authoritative Information";
case 204: return "No Content";
case 205: return "Reset Content";
case 206: return "Partial Content";
case 300: return "Multiple Choices";
case 301: return "Moved Permanently";
case 302: return "Found";
case 303: return "See Other";
case 304: return "Not Modified";
case 305: return "Use Proxy";
case 306: return " (Unused)";
case 307: return "Temporary Redirect";
case 400: return "Bad Request";
case 401: return "Unauthorized";
case 402: return "Payment Required";
case 403: return "Forbidden";
case 404: return "Not Found";
case 405: return "Method Not Allowed";
case 406: return "Not Acceptable";
case 407: return "Proxy Authentication Required";
case 408: return "Request Timeout";
case 409: return "Conflict";
case 410: return "Gone";
case 411: return "Length Required";
case 412: return "Precondition Failed";
case 413: return "Request Entity Too Large";
case 414: return "Request-URI Too Long";
case 415: return "Unsupported Media Type";
case 416: return "Requested Range Not Satisfiable";
case 417: return "Expectation Failed";
case 421: return "Misdirected Request";
case 500: return "Internal Server Error";
case 501: return "Not Implemented";
case 502: return "Bad Gateway";
case 503: return "Service Unavailable";
case 504: return "Gateway Timeout";
case 505: return "HTTP Version Not Supported";
default: return "Unknown Error";
}
}
void
tr_http_escape (struct evbuffer * out,
const char * str,
size_t len,
bool escape_slashes)
{
if (str == NULL)
return;
if (len == TR_BAD_SIZE)
len = strlen (str);
for (const char * end = str + len; str != end; ++str)
{
if ((*str == ',') || (*str == '-')
|| (*str == '.')
|| (('0' <= *str) && (*str <= '9'))
|| (('A' <= *str) && (*str <= 'Z'))
|| (('a' <= *str) && (*str <= 'z'))
|| ((*str == '/') && (!escape_slashes)))
evbuffer_add_printf (out, "%c", *str);
else
evbuffer_add_printf (out, "%%%02X", (unsigned)(*str&0xFF));
}
}
char *
tr_http_unescape (const char * str, size_t len)
{
char * tmp = curl_unescape (str, len);
char * ret = tr_strdup (tmp);
curl_free (tmp);
return ret;
}
static bool
is_rfc2396_alnum (uint8_t ch)
{
return ('0' <= ch && ch <= '9')
|| ('A' <= ch && ch <= 'Z')
|| ('a' <= ch && ch <= 'z')
|| ch == '.'
|| ch == '-'
|| ch == '_'
|| ch == '~';
}
void
tr_http_escape_sha1 (char * out, const uint8_t * sha1_digest)
{
const uint8_t * in = sha1_digest;
const uint8_t * end = in + SHA_DIGEST_LENGTH;
while (in != end)
if (is_rfc2396_alnum (*in))
*out++ = (char) *in++;
else
out += tr_snprintf (out, 4, "%%%02x", (unsigned int)*in++);
*out = '\0';
}
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