Guard the download against handlers that erase it mid-close

Track a weak_ptr lifetime handle and make erase ignore re-entrant erase.

src/command_throttle.cc

@@ -89,6 +89,24 @@ throttle_update(const char* variable, int64_t value) {
   return torrent::Object();
 }
 
+static unsigned int
+throttle_rate_to_kb(int64_t rate) {
+  if (rate < 0 || rate > std::numeric_limits<unsigned int>::max() - 1)
+    throw torrent::input_error("Throttle rate must be between 0 and 4294967294.");
+
+  return static_cast<unsigned int>(rate >> 10);
+}
+
+static void
+set_up_throttle_i64(ui::Root* root, int64_t rate) {
+  root->set_up_throttle(throttle_rate_to_kb(rate));
+}
+
+static void
+set_down_throttle_i64(ui::Root* root, int64_t rate) {
+  root->set_down_throttle(throttle_rate_to_kb(rate));
+}
+
 void
 initialize_command_throttle() {
   CMD2_ANY         ("throttle.unchoked_uploads",       std::bind(&torrent::ResourceManager::currently_upload_unchoked, torrent::resource_manager()));
@@ -125,13 +143,13 @@ initialize_command_throttle() {
   CMD2_ANY         ("throttle.global_up.rate",              std::bind(&torrent::Rate::rate, torrent::up_rate()));
   CMD2_ANY         ("throttle.global_up.total",             std::bind(&torrent::Rate::total, torrent::up_rate()));
   CMD2_ANY         ("throttle.global_up.max_rate",          std::bind(&torrent::Throttle::max_rate, torrent::up_throttle_global()));
-  CMD2_ANY_VALUE_V ("throttle.global_up.max_rate.set",      std::bind(&ui::Root::set_up_throttle_i64, control->ui(), std::placeholders::_2));
-  CMD2_ANY_VALUE_KB("throttle.global_up.max_rate.set_kb",   std::bind(&ui::Root::set_up_throttle_i64, control->ui(), std::placeholders::_2));
+  CMD2_ANY_VALUE_V ("throttle.global_up.max_rate.set",      std::bind(&set_up_throttle_i64, control->ui(), std::placeholders::_2));
+  CMD2_ANY_VALUE_KB("throttle.global_up.max_rate.set_kb",   std::bind(&set_up_throttle_i64, control->ui(), std::placeholders::_2));
   CMD2_ANY         ("throttle.global_down.rate",            std::bind(&torrent::Rate::rate, torrent::down_rate()));
   CMD2_ANY         ("throttle.global_down.total",           std::bind(&torrent::Rate::total, torrent::down_rate()));
   CMD2_ANY         ("throttle.global_down.max_rate",        std::bind(&torrent::Throttle::max_rate, torrent::down_throttle_global()));
-  CMD2_ANY_VALUE_V ("throttle.global_down.max_rate.set",    std::bind(&ui::Root::set_down_throttle_i64, control->ui(), std::placeholders::_2));
-  CMD2_ANY_VALUE_KB("throttle.global_down.max_rate.set_kb", std::bind(&ui::Root::set_down_throttle_i64, control->ui(), std::placeholders::_2));
+  CMD2_ANY_VALUE_V ("throttle.global_down.max_rate.set",    std::bind(&set_down_throttle_i64, control->ui(), std::placeholders::_2));
+  CMD2_ANY_VALUE_KB("throttle.global_down.max_rate.set_kb", std::bind(&set_down_throttle_i64, control->ui(), std::placeholders::_2));
 
   // Temporary names, need to change this to accept real rates rather
   // than kB.

src/core/download.h

@@ -51,6 +51,14 @@ public:
   bool                is_hash_checking() const                 { return m_download.is_hash_checking(); }
 
   bool                is_hash_failed() const                   { return m_hashFailed; }
+
+  // Expires once the download is erased, even if other owners keep the
+  // object alive. Take it before triggering events that may erase.
+  std::weak_ptr<void> lifetime() const                         { return m_lifetime; }
+  void                release_lifetime()                       { m_lifetime.reset(); }
+
+  bool                is_erasing() const                       { return m_erasing; }
+  void                set_erasing()                            { m_erasing = true; }
   void                set_hash_failed(bool v)                  { m_hashFailed = v; }
 
   download_type*       download()                              { return &m_download; }
@@ -103,6 +111,8 @@ private:
   // Store the FileList instance so we can use slots etc on it.
   download_type       m_download;
   bool                m_hashFailed{};
+  bool                m_erasing{};
+  std::shared_ptr<void> m_lifetime{std::make_shared<char>()};
   std::string         m_message;
   uint32_t            m_resumeFlags{default_resume_flags};
   unsigned int        m_group{};

src/core/download_list.cc

@@ -194,6 +194,12 @@ DownloadList::erase(iterator itr) {
   if (itr == end())
     throw torrent::internal_error("DownloadList::erase(...) could not find download.");
 
+  // An event handler below may erase the same download again.
+  if ((*itr)->is_erasing())
+    return std::next(itr);
+
+  (*itr)->set_erasing();
+
   lt_log_print_info(torrent::LOG_TORRENT_INFO, (*itr)->info(), "download_list", "Erasing download.");
 
   // Makes sure close doesn't restart hashing of this download.
@@ -207,6 +213,7 @@ DownloadList::erase(iterator itr) {
   for (auto v : *control->view_manager())
     v->erase(itr->get());
 
+  (*itr)->release_lifetime();
   torrent::download_remove(*(*itr)->download());
 
   return base_type::erase(itr);
@@ -275,6 +282,7 @@ void
 DownloadList::close_directly(Download* download) {
   lt_log_print_info(torrent::LOG_TORRENT_INFO, download->info(), "download_list", "Closing download directly.");
 
+  auto lifetime   = download->lifetime();
   bool was_active = download->download()->info()->is_active();
   bool was_open   = download->download()->info()->is_open();
 
@@ -283,11 +291,19 @@ DownloadList::close_directly(Download* download) {
 
   if (was_active) {
     DL_TRIGGER_EVENT(download, "event.download.paused");
+
+    if (lifetime.expired())
+      return;
+
     update_paused_state(download);
   }
 
   if (was_open) {
     DL_TRIGGER_EVENT(download, "event.download.hash_removed");
+
+    if (lifetime.expired())
+      return;
+
     DL_TRIGGER_EVENT(download, "event.download.closed");
   }
 }
@@ -330,8 +346,13 @@ DownloadList::close_throw(Download* download) {
   // When pause gets called it will clear the initial hash check state
   // and set hash failed. This should ensure hashing doesn't restart
   // until resume gets called.
+  auto lifetime = download->lifetime();
+
   pause(download);
 
+  if (lifetime.expired())
+    return;
+
   // Check for is_open after pause due to hashing.
   if (!download->is_open())
     return;
@@ -351,6 +372,10 @@ DownloadList::close_throw(Download* download) {
     throw torrent::internal_error("DownloadList::close_throw(...) called but we're going into a hashing loop.");
 
   DL_TRIGGER_EVENT(download, "event.download.hash_removed");
+
+  if (lifetime.expired())
+    return;
+
   DL_TRIGGER_EVENT(download, "event.download.closed");
 }
 
@@ -457,6 +482,8 @@ DownloadList::pause(Download* download, int flags) {
 
   lt_log_print_info(torrent::LOG_TORRENT_INFO, download->info(), "download_list", "Pausing download: flags:%0x.", flags);
 
+  auto lifetime = download->lifetime();
+
   try {
 
     download->set_resume_flags(Download::default_resume_flags);
@@ -470,6 +497,9 @@ DownloadList::pause(Download* download, int flags) {
       rpc::call_command_set_value("d.hashing.set", Download::variable_hashing_stopped, rpc::make_target(download));
 
       DL_TRIGGER_EVENT(download, "event.download.hash_removed");
+
+      if (lifetime.expired())
+        return;
     }
 
     if (!download->download()->info()->is_active())
@@ -483,6 +513,9 @@ DownloadList::pause(Download* download, int flags) {
     // view.
     DL_TRIGGER_EVENT(download, "event.download.paused");
 
+    if (lifetime.expired())
+      return;
+
     update_paused_state(download);
 
     // Save the state after all the slots, etc have been called so we
@@ -563,9 +596,15 @@ DownloadList::hash_done(Download* download) {
     rpc::call_command("d.complete.set", (int64_t)download->is_done(), rpc::make_target(download));
     torrent::resume_save_progress(*download->download(), download->download()->bencode()->get_key("libtorrent_resume"));
 
-    if (rpc::call_command_value("d.state", rpc::make_target(download)) == 1)
+    if (rpc::call_command_value("d.state", rpc::make_target(download)) == 1) {
+      auto lifetime = download->lifetime();
+
       resume(download, download->resume_flags());
 
+      if (lifetime.expired())
+        return;
+    }
+
     break;
 
   case Download::variable_hashing_last:
@@ -602,11 +641,24 @@ DownloadList::hash_queue(Download* download, int type) {
 
   // HACK
   if (download->is_open()) {
+    auto lifetime = download->lifetime();
+
     pause(download, torrent::Download::stop_skip_tracker);
+
+    if (lifetime.expired())
+      return;
+
     download->download()->close();
 
     DL_TRIGGER_EVENT(download, "event.download.hash_removed");
+
+    if (lifetime.expired())
+      return;
+
     DL_TRIGGER_EVENT(download, "event.download.closed");
+
+    if (lifetime.expired())
+      return;
   }
 
   torrent::resume_clear_progress(*download->download(), download->download()->bencode()->get_key("libtorrent_resume"));
@@ -682,12 +734,12 @@ DownloadList::confirm_finished(Download* download) {
   // up/downloaded baseline.
   download->download()->send_completed();
 
-  // Save the hash in case the finished event erases it.
-  torrent::HashString infohash = download->info()->hash();
+  // The finished event may erase the download.
+  auto lifetime = download->lifetime();
 
   DL_TRIGGER_EVENT(download, "event.download.finished");
 
-  if (find(infohash) == end())
+  if (lifetime.expired())
     return;
 
 //   if (download->resume_flags() != Download::default_resume_flags)

src/rpc/jsonrpc.cc

@@ -2,8 +2,10 @@
 
 #include "rpc/jsonrpc.h"
 
+#include <cstddef>
 #include <cstdint>
 #include <string>
+#include <utility>
 #include <torrent/common.h>
 #include <torrent/torrent.h>
 #include <torrent/utils/string_manip.h>
@@ -223,13 +225,49 @@ handle_notification(const json& request) noexcept {
   }
 }
 
+namespace {
+
+using json_input_adapter = decltype(nlohmann::detail::input_adapter(std::declval<const char*>(), std::declval<const char*>()));
+using json_dom_parser    = nlohmann::detail::json_sax_dom_parser<json, json_input_adapter>;
+
+class json_depth_limited_parser : public json_dom_parser {
+public:
+  explicit json_depth_limited_parser(json& root) : json_dom_parser(root) {}
+
+  bool start_object(std::size_t length) { return enter() && json_dom_parser::start_object(length); }
+  bool start_array(std::size_t length) { return enter() && json_dom_parser::start_array(length); }
+
+  bool end_object() { m_depth--; return json_dom_parser::end_object(); }
+  bool end_array() { m_depth--; return json_dom_parser::end_array(); }
+
+private:
+  bool enter() { return ++m_depth <= max_json_depth; }
+
+  uint32_t m_depth{0};
+};
+
+} // namespace
+
 bool
 JsonRpc::process(const char* in_buffer, uint32_t length, slot_write callback) {
   json response;
   json body;
 
+  if (length > m_size_limit) {
+    auto err_str = json_error(JSONRPC_INVALID_REQUEST_ERROR, "content size exceeds maximum RPC limit", nullptr).dump();
+
+    return callback(err_str.c_str(), err_str.size());
+  }
+
   try {
-    body = json::parse(in_buffer, in_buffer + length);
+    json_depth_limited_parser handler(body);
+
+    if (!json::sax_parse(in_buffer, in_buffer + length, &handler)) {
+      auto err_str = json_error(JSONRPC_INVALID_REQUEST_ERROR, "maximum nesting depth exceeded", nullptr).dump();
+
+      return callback(err_str.c_str(), err_str.size());
+    }
+
     switch (body.type()) {
     case json::value_t::object: {
       if (!body.contains("id")) {

src/rpc/jsonrpc.h

@@ -5,6 +5,8 @@
 
 #include <cstdint>
 
+#include "rpc/scgi_task.h"
+
 namespace rpc {
 
 class JsonRpc {
@@ -17,6 +19,11 @@ public:
   bool process(const char* in_buffer, uint32_t length, slot_write callback);
 
   void insert_command(const char* name, const char* parm, const char* doc) {};
+
+  void set_size_limit(uint64_t size) { m_size_limit = size; }
+
+private:
+  uint64_t m_size_limit{SCgiTask::max_content_size};
 };
 
 } // namespace rpc

src/rpc/rpc_manager.cc

@@ -176,6 +176,7 @@ RpcManager::set_size_limit(uint64_t size) {
     throw torrent::input_error("XMLRPC size limit is too small to hold a request.");
 
   m_xmlrpc.set_size_limit(size);
+  m_jsonrpc.set_size_limit(size);
 }
 
 void

src/rpc/xmlrpc_tinyxml2.cc

@@ -326,15 +326,20 @@ process_document(const tinyxml2::XMLDocument* doc, tinyxml2::XMLPrinter* printer
     auto& result_list     = result.as_list();
     auto  parent_elements = element_access(doc->RootElement(), {"params", "param", "value", "array", "data"});
     for (auto child = parent_elements->FirstChildElement("value"); child; child = child->NextSiblingElement("value")) {
-      auto sub_method_name = element_access(child, {"struct", "member", "value", "string"})->GetText();
+      auto method_name_member = element_access(child, {"struct", "member"});
+      auto member_name        = method_name_member->FirstChildElement("name");
+
+      if (member_name == nullptr || member_name->GetText() == nullptr ||
+          std::strncmp(member_name->GetText(), "methodName", sizeof("methodName")) != 0)
+        throw rpc_error(XMLRPC_PARSE_ERROR, "multicall struct's first member must be methodName");
+
+      auto sub_method_name = element_access(method_name_member, {"value", "string"})->GetText();
 
       if (sub_method_name == nullptr)
         throw rpc_error(XMLRPC_PARSE_ERROR, "multicall methodName element is empty");
       // If sub_params ends up a nullptr at the end of this if-chian,
       // execute_command will turn it into an empty list
-      auto sub_params = element_access(child, {"struct", "member"});
-      if (sub_params != nullptr)
-        sub_params = sub_params->NextSiblingElement("member");
+      auto sub_params = method_name_member->NextSiblingElement("member");
       if (sub_params != nullptr)
         sub_params = sub_params->FirstChildElement("value");
       if (sub_params != nullptr)

src/session/download_storer.cc

@@ -2,6 +2,7 @@
 
 #include "download_storer.h"
 
+#include <cerrno>
 #include <fcntl.h>
 #include <fstream>
 #include <unistd.h>
@@ -116,28 +117,36 @@ is_correct_format(const std::string& f) {
 
 void
 save_stream(const std::string& path, bool use_fsyncdisk, const std::stringstream& stream) {
-  std::fstream output(path.c_str(), std::ios::out | std::ios::trunc);
+  // Remove any leftover temporary file first so that O_EXCL only ever fails on
+  // an entry that appeared after the unlink, and O_NOFOLLOW keeps a symlink
+  // planted in the session directory from redirecting the write.
+  if (::unlink(path.c_str()) == -1 && errno != ENOENT)
+    throw torrent::storage_error("failed to remove stale file : " + path);
 
   // TODO: If we cannot open more files, wait for some to finish and try again.
-  if (!output.is_open())
-    throw torrent::storage_error("failed to open file for writing : " + path);
-
-  output << stream.rdbuf();
-
-  if (!output.good())
-    throw torrent::storage_error("failed to write stream to file : " + path);
-
-  // The data only reaches the kernel here, so this is where a full disk is seen.
-  output.close();
-
-  if (!output.good())
-    throw torrent::storage_error("failed to flush stream to file : " + path);
-
-  // Ensure that the new file is actually written to the disk
-  int fd = ::open(path.c_str(), O_WRONLY);
+  int fd = ::open(path.c_str(), O_WRONLY | O_CREAT | O_EXCL | O_NOFOLLOW, 0600);
 
   if (fd < 0)
-    throw torrent::storage_error("failed to open file descriptor for fsync : " + path);
+    throw torrent::storage_error("failed to open file for writing : " + path);
+
+  const auto  data      = stream.view();
+  std::size_t remaining = data.size();
+  const char* cursor    = data.data();
+
+  while (remaining != 0) {
+    ssize_t result = ::write(fd, cursor, remaining);
+
+    if (result == -1) {
+      if (errno == EINTR)
+        continue;
+
+      ::close(fd);
+      throw torrent::storage_error("failed to write stream to file : " + path);
+    }
+
+    cursor    += result;
+    remaining -= result;
+  }
 
   if (use_fsyncdisk) {
 #ifdef __APPLE__
@@ -152,6 +161,7 @@ save_stream(const std::string& path, bool use_fsyncdisk, const std::stringstream
     }
   }
 
+  // A full disk may only be seen when the descriptor is closed.
   if (::close(fd) == -1)
     throw torrent::storage_error("failed to close file descriptor : " + path);
 }

src/ui/root.h

@@ -70,10 +70,6 @@ public:
   void                set_down_throttle(unsigned int throttle);
   void                set_up_throttle(unsigned int throttle);
 
-  // Rename to raw or something, make base function.
-  void                set_down_throttle_i64(int64_t throttle) { set_down_throttle(throttle >> 10); }
-  void                set_up_throttle_i64(int64_t throttle)   { set_up_throttle(throttle >> 10); }
-
   void                adjust_down_throttle(int throttle);
   void                adjust_up_throttle(int throttle);
 

src/utils/directory.cc

@@ -5,6 +5,7 @@
 #include <algorithm>
 #include <cstdlib>
 #include <dirent.h>
+#include <fcntl.h>
 #include <functional>
 #include <sys/stat.h>
 #include <torrent/exceptions.h>
@@ -13,6 +14,24 @@
 
 namespace utils {
 
+namespace {
+
+uint8_t
+entry_type_from_mode(mode_t mode) {
+  if (S_ISREG(mode))
+    return DT_REG;
+
+  if (S_ISDIR(mode))
+    return DT_DIR;
+
+  if (S_ISLNK(mode))
+    return DT_LNK;
+
+  return DT_UNKNOWN;
+}
+
+} // namespace
+
 // Keep this?
 bool
 Directory::is_valid() const {
@@ -38,9 +57,6 @@ Directory::update(int flags) {
     return false;
 
   struct dirent* entry;
-#ifdef __sun__
-  struct stat s;
-#endif
 
   while ((entry = readdir(d)) != NULL) {
     if ((flags & update_hide_dot) && entry->d_name[0] == '.')
@@ -49,16 +65,22 @@ Directory::update(int flags) {
     iterator itr = base_type::insert(end(), value_type());
 
 #ifdef __sun__
-    stat(entry->d_name, &s);
     itr->s_fileno = entry->d_ino;
     itr->s_reclen = 0;
-    itr->s_type = s.st_mode;
+    itr->s_type   = DT_UNKNOWN;
 #else
     itr->s_fileno = entry->d_fileno;
     itr->s_reclen = entry->d_reclen;
     itr->s_type   = entry->d_type;
 #endif
 
+    if (itr->s_type == DT_UNKNOWN) {
+      struct stat st;
+
+      if (fstatat(dirfd(d), entry->d_name, &st, AT_SYMLINK_NOFOLLOW) == 0)
+        itr->s_type = entry_type_from_mode(st.st_mode);
+    }
+
 #ifdef DIRENT_NAMLEN_EXISTS_FOOBAR
     itr->s_name   = std::string(entry->d_name, entry->d_name + entry->d_namlen);
 #else

src/utils/directory.h

@@ -2,14 +2,14 @@
 #define RTORRENT_UTILS_DIRECTORY_H
 
 #include <cstdint>
+#include <dirent.h>
 #include <string>
 #include <vector>
 
 namespace utils {
 
 struct directory_entry {
-  // Fix.
-  bool is_file() const { return true; }
+  bool is_file() const { return s_type == DT_REG; }
 
   // The name and types should match POSIX.
   uint32_t            s_fileno;

test/Makefile.am

@@ -67,6 +67,10 @@ rtorrent_Test_Src_SOURCES = $(rtorrent_Test_Common) \
 	src/test_command_path.h \
 	src/test_command_string.cc \
 	src/test_command_string.h \
+	src/test_command_throttle.cc \
+	src/test_command_throttle.h \
+	src/test_session_storer.cc \
+	src/test_session_storer.h \
 	src/test_setup.cc \
 	src/test_setup.h \
 	src/test_ui_download_list.cc \

test/rpc/test_jsonrpc.cc

@@ -173,3 +173,82 @@ TestJsonrpc::test_response_size_limit() {
                          output.size() <= rpc::SCgiTask::max_response_size);
   CPPUNIT_ASSERT_EQUAL(expected, output);
 }
+
+// The bound is applied while the document is parsed: json_to_object only ever
+// walks "params", and by the time it runs the whole tree already exists.
+void
+TestJsonrpc::test_depth_limit() {
+  // A JSON string holding a quote and brackets that must not be counted.
+  const std::string tricky = R"("\"[[[")";
+
+  std::vector<std::tuple<std::string, std::string, std::string>> requests = {
+    std::make_tuple("Nesting under the limit is accepted",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": ["", )" +
+                      std::string(1000, '[') + std::string(1000, ']') + R"(], "id": 1})",
+                    R"({"id":1,"jsonrpc":"2.0","result":[)" +
+                      std::string(1000, '[') + std::string(1000, ']') + R"(]})"),
+
+    // Nesting outside "params" is never converted, so json_to_object's own
+    // bound never sees it.
+    std::make_tuple("Nesting outside params is rejected",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": [""], "id": 1, "x": )" +
+                      std::string(2000, '[') + std::string(2000, ']') + R"(})",
+                    R"({"error":{"code":-32600,"message":"maximum nesting depth exceeded"},"id":null,"jsonrpc":"2.0"})"),
+
+    std::make_tuple("Nesting over the limit is rejected",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": ["", )" +
+                      std::string(2000, '[') + std::string(2000, ']') + R"(], "id": 1})",
+                    R"({"error":{"code":-32600,"message":"maximum nesting depth exceeded"},"id":null,"jsonrpc":"2.0"})"),
+
+    std::make_tuple("Brackets inside a string are not nesting",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": ["", ")" +
+                      std::string(2000, '[') + R"("], "id": 1})",
+                    R"({"id":1,"jsonrpc":"2.0","result":[")" +
+                      std::string(2000, '[') + R"("]})"),
+
+    std::make_tuple("An escaped quote does not end a string",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": ["", )" + tricky + R"(, ")" +
+                      std::string(2000, '[') + R"("], "id": 1})",
+                    R"({"id":1,"jsonrpc":"2.0","result":[)" + tricky + R"(,")" +
+                      std::string(2000, '[') + R"("]})"),
+
+    // The bound is on the whole document, so the outer object and the params
+    // array are two of the 1024 containers and 1022 are left for the payload.
+    std::make_tuple("Nesting one below the limit is accepted",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": ["", )" +
+                      std::string(1021, '[') + std::string(1021, ']') + R"(], "id": 1})",
+                    R"({"id":1,"jsonrpc":"2.0","result":[)" +
+                      std::string(1021, '[') + std::string(1021, ']') + R"(]})"),
+
+    std::make_tuple("Nesting at the limit is accepted",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": ["", )" +
+                      std::string(1022, '[') + std::string(1022, ']') + R"(], "id": 1})",
+                    R"({"id":1,"jsonrpc":"2.0","result":[)" +
+                      std::string(1022, '[') + std::string(1022, ']') + R"(]})"),
+
+    std::make_tuple("Nesting one over the limit is rejected",
+                    R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": ["", )" +
+                      std::string(1023, '[') + std::string(1023, ']') + R"(], "id": 1})",
+                    R"({"error":{"code":-32600,"message":"maximum nesting depth exceeded"},"id":null,"jsonrpc":"2.0"})"),
+  };
+
+  for (auto& test : requests) {
+    std::string output;
+    m_jsonrpc.process(std::get<1>(test).c_str(), std::get<1>(test).size(), [&output](const char* c, uint32_t l) { output.append(c, l); return true; });
+    CPPUNIT_ASSERT_EQUAL_MESSAGE(std::get<0>(test), std::get<2>(test), output);
+  }
+}
+
+// network.xmlrpc.size_limit is the only knob bounding how much input a single
+// request may spend memory on, and it has to bound the JSON path too.
+void
+TestJsonrpc::test_size_limit() {
+  const std::string request = R"({"jsonrpc": "2.0", "method": "jsonrpc_reflect", "params": [""], "id": 1})";
+  const std::string expected = R"({"error":{"code":-32600,"message":"content size exceeds maximum RPC limit"},"id":null,"jsonrpc":"2.0"})";
+
+  std::string output;
+  m_jsonrpc.set_size_limit(1);
+  m_jsonrpc.process(request.c_str(), request.size(), [&output](const char* c, uint32_t l) { output.append(c, l); return true; });
+
+  CPPUNIT_ASSERT_EQUAL(expected, output);
+}

test/rpc/test_jsonrpc.h

@@ -9,6 +9,8 @@ class TestJsonrpc : public test_fixture {
 
   CPPUNIT_TEST(test_basics);
   CPPUNIT_TEST(test_response_size_limit);
+  CPPUNIT_TEST(test_depth_limit);
+  CPPUNIT_TEST(test_size_limit);
 
   CPPUNIT_TEST_SUITE_END();
 
@@ -18,6 +20,8 @@ public:
 
   void test_basics();
   void test_response_size_limit();
+  void test_depth_limit();
+  void test_size_limit();
 
 private:
   std::unique_ptr<TestMainThread> m_test_main_thread;

test/rpc/test_xmlrpc.cc

@@ -192,12 +192,54 @@ TestXmlrpc::test_response_size_limit() {
   CPPUNIT_ASSERT_EQUAL(expected, output);
 }
 
+namespace {
+
+const std::string multicall_method_name =
+  "<member><name>methodName</name><value><string>xmlrpc_reflect</string></value></member>";
+const std::string multicall_params =
+  "<member><name>params</name><value><array><data>"
+  "<value><string></string></value><value><string>a</string></value>"
+  "</data></array></value></member>";
+
+std::string
+multicall_request(const std::string& members) {
+  return "<?xml version=\"1.0\"?><methodCall><methodName>system.multicall</methodName>"
+         "<params><param><value><array><data><value><struct>" + members +
+         "</struct></value></data></array></value></param></params></methodCall>";
+}
+
+}
+
+void
+TestXmlrpc::test_multicall_member_order() {
+  auto call = [this](const std::string& input) {
+    std::string output;
+    m_xmlrpc.process(input.c_str(), input.size(), [&output](const char* c, uint32_t l){ output.append(c, l); return true;});
+    return output;
+  };
+
+  // methodName first is the only order accepted; the positive control proves
+  // the harness drives the real code path rather than a stub.
+  std::string ordered = call(multicall_request(multicall_method_name + multicall_params));
+  CPPUNIT_ASSERT(ordered.find("faultCode") == std::string::npos);
+
+  // params before methodName is rejected with a clear top-level fault,
+  // instead of the "could not find expected element string" of a positional read.
+  std::string expected_fault =
+    "<?xml version=\"1.0\"?><methodResponse><fault><value><struct>"
+    "<member><name>faultCode</name><value><i8>-503</i8></value></member>"
+    "<member><name>faultString</name><value><string>multicall struct's first member must be methodName</string></value></member>"
+    "</struct></value></fault></methodResponse>";
+  CPPUNIT_ASSERT_EQUAL(expected_fault, call(multicall_request(multicall_params + multicall_method_name)));
+}
+
 #else
 
 void TestXmlrpc::test_invalid_utf8() {}
 void TestXmlrpc::test_basics() {}
 void TestXmlrpc::test_size_limit() {}
 void TestXmlrpc::test_response_size_limit() {}
+void TestXmlrpc::test_multicall_member_order() {}
 void TestXmlrpc::setUp() {}
 void TestXmlrpc::tearDown() {}
 

test/rpc/test_xmlrpc.h

@@ -11,6 +11,7 @@ class TestXmlrpc : public test_fixture {
   CPPUNIT_TEST(test_invalid_utf8);
   CPPUNIT_TEST(test_size_limit);
   CPPUNIT_TEST(test_response_size_limit);
+  CPPUNIT_TEST(test_multicall_member_order);
 
   CPPUNIT_TEST_SUITE_END();
 
@@ -24,6 +25,7 @@ public:
   void test_invalid_utf8();
   void test_size_limit();
   void test_response_size_limit();
+  void test_multicall_member_order();
 
 private:
   std::unique_ptr<TestMainThread> m_test_main_thread;

test/src/test_command_throttle.cc

@@ -0,0 +1,102 @@
+#include "config.h"
+
+#include "test/src/test_command_throttle.h"
+
+#include <torrent/throttle.h>
+#include <torrent/torrent.h>
+
+#include "core/manager.h"
+#include "control.h"
+#include "globals.h"
+#include "rpc/parse_commands.h"
+
+CPPUNIT_TEST_SUITE_REGISTRATION(TestCommandThrottle);
+
+void initialize_command_throttle();
+
+static void
+call_set(const char* key, const char* value) {
+  rpc::commands.call_command(key, torrent::Object(std::string(value)));
+}
+
+static void
+call_named(const char* key, const char* name, const char* value) {
+  torrent::Object::list_type args;
+  args.push_back(torrent::Object(std::string(name)));
+  args.push_back(torrent::Object(std::string(value)));
+
+  rpc::commands.call_command(key, torrent::Object::create_list_range(args.begin(), args.end()));
+}
+
+static uint64_t
+down_rate() {
+  return torrent::down_throttle_global()->max_rate();
+}
+
+void
+TestCommandThrottle::setUp() {
+  torrent::initialize_main_thread();
+  torrent::initialize();
+
+  if (control == nullptr)
+    control = new Control;
+
+  if (!rpc::commands.has("throttle.global_down.max_rate.set_kb"))
+    initialize_command_throttle();
+}
+
+void
+TestCommandThrottle::tearDown() {
+  torrent::cleanup();
+}
+
+void
+TestCommandThrottle::test_global_rate_in_range() {
+  call_set("throttle.global_down.max_rate.set_kb", "1024");
+  CPPUNIT_ASSERT_EQUAL(uint64_t{1048576}, down_rate());
+
+  call_set("throttle.global_down.max_rate.set_kb", "4194303");
+  CPPUNIT_ASSERT_EQUAL(uint64_t{4294966272}, down_rate());
+
+  call_set("throttle.global_down.max_rate.set", "4294966272");
+  CPPUNIT_ASSERT_EQUAL(uint64_t{4294966272}, down_rate());
+}
+
+void
+TestCommandThrottle::test_global_rate_kb_out_of_range() {
+  call_set("throttle.global_down.max_rate.set_kb", "1024");
+
+  CPPUNIT_ASSERT_THROW(call_set("throttle.global_down.max_rate.set_kb", "4194304"), torrent::input_error);
+  CPPUNIT_ASSERT_EQUAL(uint64_t{1048576}, down_rate());
+}
+
+void
+TestCommandThrottle::test_global_rate_bytes_out_of_range() {
+  call_set("throttle.global_down.max_rate.set", "1048576");
+
+  CPPUNIT_ASSERT_THROW(call_set("throttle.global_down.max_rate.set", "4294967296"), torrent::input_error);
+  CPPUNIT_ASSERT_EQUAL(uint64_t{1048576}, down_rate());
+}
+
+void
+TestCommandThrottle::test_global_rate_negative() {
+  call_set("throttle.global_down.max_rate.set", "1048576");
+
+  CPPUNIT_ASSERT_THROW(call_set("throttle.global_down.max_rate.set", "-1"), torrent::input_error);
+  CPPUNIT_ASSERT_EQUAL(uint64_t{1048576}, down_rate());
+}
+
+void
+TestCommandThrottle::test_named_rate_in_range() {
+  call_named("throttle.down", "test_named_in_range", "1024");
+
+  auto itr = control->core()->throttles().find("test_named_in_range");
+
+  CPPUNIT_ASSERT(itr != control->core()->throttles().end());
+  CPPUNIT_ASSERT_EQUAL(uint64_t{1048576}, itr->second.second->max_rate());
+}
+
+void
+TestCommandThrottle::test_named_rate_out_of_range() {
+  CPPUNIT_ASSERT_THROW(call_named("throttle.down", "test_named_out_of_range", "18014398509481984"), torrent::input_error);
+}

test/src/test_command_throttle.h

@@ -0,0 +1,25 @@
+#include "test/helpers/test_fixture.h"
+
+class TestCommandThrottle : public test_fixture {
+  CPPUNIT_TEST_SUITE(TestCommandThrottle);
+
+  CPPUNIT_TEST(test_global_rate_in_range);
+  CPPUNIT_TEST(test_global_rate_kb_out_of_range);
+  CPPUNIT_TEST(test_global_rate_bytes_out_of_range);
+  CPPUNIT_TEST(test_global_rate_negative);
+  CPPUNIT_TEST(test_named_rate_in_range);
+  CPPUNIT_TEST(test_named_rate_out_of_range);
+
+  CPPUNIT_TEST_SUITE_END();
+
+public:
+  void setUp();
+  void tearDown();
+
+  void test_global_rate_in_range();
+  void test_global_rate_kb_out_of_range();
+  void test_global_rate_bytes_out_of_range();
+  void test_global_rate_negative();
+  void test_named_rate_in_range();
+  void test_named_rate_out_of_range();
+};

test/src/test_session_storer.cc

@@ -0,0 +1,152 @@
+#include "config.h"
+
+#include "test/src/test_session_storer.h"
+
+#include <cstdlib>
+#include <dirent.h>
+#include <fstream>
+#include <sstream>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "session/download_storer.h"
+#include "utils/directory.h"
+
+CPPUNIT_TEST_SUITE_REGISTRATION(TestSessionStorer);
+
+namespace {
+
+const char* entry_name = "0123456789ABCDEF0123456789ABCDEF01234567.torrent";
+const char* link_name  = "FEDCBA9876543210FEDCBA9876543210FEDCBA98.torrent";
+
+void
+write_file(const std::string& path, const std::string& content) {
+  std::ofstream file(path.c_str());
+
+  file << content;
+  file.close();
+
+  CPPUNIT_ASSERT(file.good());
+}
+
+std::string
+read_file(const std::string& path) {
+  std::ifstream    file(path.c_str());
+  std::stringstream buffer;
+
+  buffer << file.rdbuf();
+  return buffer.str();
+}
+
+void
+save_session_files(const std::string& path) {
+  std::stringstream torrent_stream("torrent-data");
+  std::stringstream rtorrent_stream("rtorrent-data");
+  std::stringstream libtorrent_stream("libtorrent-data");
+
+  session::DownloadStorer::save_and_move_streams(path, false, &torrent_stream, &rtorrent_stream, &libtorrent_stream);
+}
+
+unsigned int
+permissions_of(const std::string& path) {
+  struct stat st;
+
+  CPPUNIT_ASSERT_EQUAL(0, ::stat(path.c_str(), &st));
+  return st.st_mode & 07777;
+}
+
+void
+remove_directory(const std::string& path) {
+  DIR* d = ::opendir(path.c_str());
+
+  if (d == NULL)
+    return;
+
+  struct dirent* entry;
+
+  while ((entry = ::readdir(d)) != NULL) {
+    if (entry->d_name[0] == '.' && (entry->d_name[1] == '\0' || (entry->d_name[1] == '.' && entry->d_name[2] == '\0')))
+      continue;
+
+    ::unlink((path + "/" + entry->d_name).c_str());
+  }
+
+  ::closedir(d);
+  ::rmdir(path.c_str());
+}
+
+} // namespace
+
+void
+TestSessionStorer::setUp() {
+  test_fixture::setUp();
+
+  char temp_dir[] = "/tmp/rtorrent_test_session_XXXXXX";
+
+  CPPUNIT_ASSERT(mkdtemp(temp_dir) != nullptr);
+
+  m_temp_dir    = temp_dir;
+  m_session_dir = m_temp_dir + "/session";
+
+  CPPUNIT_ASSERT_EQUAL(0, ::mkdir(m_session_dir.c_str(), 0755));
+}
+
+void
+TestSessionStorer::tearDown() {
+  remove_directory(m_session_dir);
+  remove_directory(m_temp_dir);
+
+  test_fixture::tearDown();
+}
+
+// A symlink planted where the next temporary session file will be written must
+// not redirect the write to the file it points at.
+void
+TestSessionStorer::test_temp_file_symlink_is_not_followed() {
+  auto outside = m_temp_dir + "/outside.txt";
+  auto path    = m_session_dir + "/" + entry_name;
+
+  write_file(outside, "original");
+  CPPUNIT_ASSERT_EQUAL(0, ::symlink(outside.c_str(), (path + ".new").c_str()));
+
+  save_session_files(path);
+
+  CPPUNIT_ASSERT_EQUAL(std::string("original"), read_file(outside));
+  CPPUNIT_ASSERT_EQUAL(std::string("torrent-data"), read_file(path));
+}
+
+// Session files carry tracker announce urls, so they must not be readable by
+// other users regardless of the umask rtorrent was started with.
+void
+TestSessionStorer::test_saved_files_are_owner_only() {
+  auto path       = m_session_dir + "/" + entry_name;
+  auto prev_umask = ::umask(0);
+
+  save_session_files(path);
+  ::umask(prev_umask);
+
+  CPPUNIT_ASSERT_EQUAL(0600u, permissions_of(path));
+  CPPUNIT_ASSERT_EQUAL(0600u, permissions_of(path + ".rtorrent"));
+  CPPUNIT_ASSERT_EQUAL(0600u, permissions_of(path + ".libtorrent_resume"));
+}
+
+// Entries listed for loading must report their real type so that a symlink in
+// the session directory is skipped instead of loaded.
+void
+TestSessionStorer::test_symlinked_entry_is_not_a_file() {
+  write_file(m_temp_dir + "/outside.txt", "d0:e");
+  write_file(m_session_dir + "/" + entry_name, "d0:e");
+
+  CPPUNIT_ASSERT_EQUAL(0, ::symlink((m_temp_dir + "/outside.txt").c_str(), (m_session_dir + "/" + link_name).c_str()));
+
+  auto entries = session::DownloadStorer::get_formated_entries(m_session_dir + "/");
+
+  CPPUNIT_ASSERT_EQUAL(size_t{2}, size_t{entries.size()});
+
+  for (const auto& entry : entries) {
+    if (entry.s_name == entry_name)
+      CPPUNIT_ASSERT(entry.is_file());
+    else
+      CPPUNIT_ASSERT(!entry.is_file());
+  }
+}

test/src/test_session_storer.h

@@ -0,0 +1,25 @@
+#include "test/helpers/test_fixture.h"
+
+#include <string>
+
+class TestSessionStorer : public test_fixture {
+  CPPUNIT_TEST_SUITE(TestSessionStorer);
+
+  CPPUNIT_TEST(test_temp_file_symlink_is_not_followed);
+  CPPUNIT_TEST(test_saved_files_are_owner_only);
+  CPPUNIT_TEST(test_symlinked_entry_is_not_a_file);
+
+  CPPUNIT_TEST_SUITE_END();
+
+public:
+  void setUp();
+  void tearDown();
+
+  void test_temp_file_symlink_is_not_followed();
+  void test_saved_files_are_owner_only();
+  void test_symlinked_entry_is_not_a_file();
+
+private:
+  std::string m_temp_dir;
+  std::string m_session_dir;
+};