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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* vim: set ts=8 sts=4 et sw=4 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/ipc/MiniTransceiver.h"
#include "chrome/common/ipc_message.h"
#include "chrome/common/ipc_message_utils.h"
#include "base/eintr_wrapper.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Sprintf.h"
#include "mozilla/ScopeExit.h"
#include "nsDebug.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <errno.h>
namespace mozilla::ipc {
static const size_t kMaxIOVecSize = 64;
static const size_t kMaxDataSize = 8 * 1024;
static const size_t kMaxNumFds = 16;
MiniTransceiver::MiniTransceiver(int aFd, DataBufferClear aDataBufClear)
: mFd(aFd),
#ifdef DEBUG
mState(STATE_NONE),
#endif
mDataBufClear(aDataBufClear) {
}
namespace {
/**
* Initialize the IO vector for sending data and the control buffer for sending
* FDs.
*/
static void InitMsgHdr(msghdr* aHdr, int aIOVSize, size_t aMaxNumFds) {
aHdr->msg_name = nullptr;
aHdr->msg_namelen = 0;
aHdr->msg_flags = 0;
// Prepare the IO vector to receive the content of message.
auto* iov = new iovec[aIOVSize];
aHdr->msg_iov = iov;
aHdr->msg_iovlen = aIOVSize;
// Prepare the control buffer to receive file descriptors.
auto* cbuf = new char[CMSG_SPACE(sizeof(int) * aMaxNumFds)];
aHdr->msg_control = cbuf;
aHdr->msg_controllen = CMSG_SPACE(sizeof(int) * aMaxNumFds);
}
/**
* Delete resources allocated by InitMsgHdr().
*/
static void DeinitMsgHdr(msghdr* aHdr) {
delete aHdr->msg_iov;
delete static_cast<char*>(aHdr->msg_control);
}
} // namespace
void MiniTransceiver::PrepareFDs(msghdr* aHdr, IPC::Message& aMsg) {
// Set control buffer to send file descriptors of the Message.
size_t num_fds = aMsg.attached_handles_.Length();
cmsghdr* cmsg = CMSG_FIRSTHDR(aHdr);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int) * num_fds);
for (size_t i = 0; i < num_fds; ++i) {
reinterpret_cast<int*>(CMSG_DATA(cmsg))[i] =
aMsg.attached_handles_[i].get();
}
// This number will be sent in the header of the message. So, we
// can check it at the other side.
aMsg.header()->num_handles = num_fds;
}
size_t MiniTransceiver::PrepareBuffers(msghdr* aHdr, IPC::Message& aMsg) {
// Set iovec to send for all buffers of the Message.
iovec* iov = aHdr->msg_iov;
size_t iovlen = 0;
size_t bytes_to_send = 0;
for (Pickle::BufferList::IterImpl iter(aMsg.Buffers()); !iter.Done();
iter.Advance(aMsg.Buffers(), iter.RemainingInSegment())) {
char* data = iter.Data();
size_t size = iter.RemainingInSegment();
iov[iovlen].iov_base = data;
iov[iovlen].iov_len = size;
iovlen++;
MOZ_ASSERT(iovlen <= kMaxIOVecSize);
bytes_to_send += size;
}
MOZ_ASSERT(bytes_to_send <= kMaxDataSize);
aHdr->msg_iovlen = iovlen;
return bytes_to_send;
}
bool MiniTransceiver::Send(IPC::Message& aMsg) {
#ifdef DEBUG
if (mState == STATE_SENDING) {
MOZ_CRASH(
"STATE_SENDING: It violates of request-response and no concurrent "
"rules");
}
mState = STATE_SENDING;
#endif
auto clean_fdset = MakeScopeExit([&] { aMsg.attached_handles_.Clear(); });
size_t num_fds = aMsg.attached_handles_.Length();
msghdr hdr{};
InitMsgHdr(&hdr, kMaxIOVecSize, num_fds);
UniquePtr<msghdr, decltype(&DeinitMsgHdr)> uniq(&hdr, &DeinitMsgHdr);
PrepareFDs(&hdr, aMsg);
DebugOnly<size_t> bytes_to_send = PrepareBuffers(&hdr, aMsg);
ssize_t bytes_written = HANDLE_EINTR(sendmsg(mFd, &hdr, 0));
if (bytes_written < 0) {
char error[128];
SprintfLiteral(error, "sendmsg: %s", strerror(errno));
NS_WARNING(error);
return false;
}
MOZ_ASSERT(bytes_written == (ssize_t)bytes_to_send,
"The message is too big?!");
return true;
}
unsigned MiniTransceiver::RecvFDs(msghdr* aHdr, int* aAllFds,
unsigned aMaxFds) {
if (aHdr->msg_controllen == 0) {
return 0;
}
unsigned num_all_fds = 0;
for (cmsghdr* cmsg = CMSG_FIRSTHDR(aHdr); cmsg;
cmsg = CMSG_NXTHDR(aHdr, cmsg)) {
MOZ_ASSERT(cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS,
"Accept only SCM_RIGHTS to receive file descriptors");
unsigned payload_sz = cmsg->cmsg_len - CMSG_LEN(0);
MOZ_ASSERT(payload_sz % sizeof(int) == 0);
// Add fds to |aAllFds|
unsigned num_part_fds = payload_sz / sizeof(int);
int* part_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));
MOZ_ASSERT(num_all_fds + num_part_fds <= aMaxFds);
memcpy(aAllFds + num_all_fds, part_fds, num_part_fds * sizeof(int));
num_all_fds += num_part_fds;
}
return num_all_fds;
}
bool MiniTransceiver::RecvData(char* aDataBuf, size_t aBufSize,
uint32_t* aMsgSize, int* aFdsBuf,
unsigned aMaxFds, unsigned* aNumFds) {
msghdr hdr;
InitMsgHdr(&hdr, 1, aMaxFds);
UniquePtr<msghdr, decltype(&DeinitMsgHdr)> uniq(&hdr, &DeinitMsgHdr);
// The buffer to collect all fds received from the socket.
int* all_fds = aFdsBuf;
unsigned num_all_fds = 0;
size_t total_readed = 0;
uint32_t msgsz = 0;
while (msgsz == 0 || total_readed < msgsz) {
// Set IO vector with the begin of the unused buffer.
hdr.msg_iov->iov_base = aDataBuf + total_readed;
hdr.msg_iov->iov_len = (msgsz == 0 ? aBufSize : msgsz) - total_readed;
// Read the socket
ssize_t bytes_readed = HANDLE_EINTR(recvmsg(mFd, &hdr, 0));
if (bytes_readed <= 0) {
// Closed or error!
return false;
}
total_readed += bytes_readed;
MOZ_ASSERT(total_readed <= aBufSize);
if (msgsz == 0) {
// Parse the size of the message.
// Get 0 if data in the buffer is no enough to get message size.
msgsz = IPC::Message::MessageSize(aDataBuf, aDataBuf + total_readed);
}
num_all_fds += RecvFDs(&hdr, all_fds + num_all_fds, aMaxFds - num_all_fds);
}
*aMsgSize = msgsz;
*aNumFds = num_all_fds;
return true;
}
bool MiniTransceiver::Recv(IPC::Message& aMsg) {
#ifdef DEBUG
if (mState == STATE_RECEIVING) {
MOZ_CRASH(
"STATE_RECEIVING: It violates of request-response and no concurrent "
"rules");
}
mState = STATE_RECEIVING;
#endif
UniquePtr<char[]> databuf = MakeUnique<char[]>(kMaxDataSize);
uint32_t msgsz = 0;
int all_fds[kMaxNumFds];
unsigned num_all_fds = 0;
if (!RecvData(databuf.get(), kMaxDataSize, &msgsz, all_fds, kMaxDataSize,
&num_all_fds)) {
return false;
}
// Create Message from databuf & all_fds.
UniquePtr<IPC::Message> msg = MakeUnique<IPC::Message>(databuf.get(), msgsz);
nsTArray<UniqueFileHandle> handles(num_all_fds);
for (unsigned i = 0; i < num_all_fds; ++i) {
handles.AppendElement(UniqueFileHandle(all_fds[i]));
}
msg->SetAttachedFileHandles(std::move(handles));
if (mDataBufClear == DataBufferClear::AfterReceiving) {
// Avoid content processes from reading the content of
// messages.
memset(databuf.get(), 0, msgsz);
}
MOZ_ASSERT(msg->header()->num_handles == msg->attached_handles_.Length(),
"The number of file descriptors in the header is different from"
" the number actually received");
aMsg = std::move(*msg);
return true;
}
} // namespace mozilla::ipc