--- /dev/null
+/*
+ * Copyright © 2014 Canonical Ltd.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authored by: Kevin DuBois <kevin.dubois@canonical.com>
+ */
+
+#include "anbox/network/fd_socket_transmission.h"
+#include "anbox/common/variable_length_array.h"
+
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <boost/exception/errinfo_errno.hpp>
+#include <boost/throw_exception.hpp>
+#include <stdexcept>
+
+namespace anbox {
+socket_error::socket_error(std::string const& message)
+ : std::system_error(errno, std::system_category(), message) {}
+
+socket_disconnected_error::socket_disconnected_error(std::string const& message)
+ : std::system_error(errno, std::system_category(), message) {}
+
+fd_reception_error::fd_reception_error(std::string const& message)
+ : std::runtime_error(message) {}
+
+void send_fds(Fd const& socket, std::vector<Fd> const& fds) {
+ if (fds.size() > 0) {
+ // We send dummy data
+ struct iovec iov;
+ char dummy_iov_data = 'M';
+ iov.iov_base = &dummy_iov_data;
+ iov.iov_len = 1;
+
+ // Allocate space for control message
+ static auto const builtin_n_fds = 5;
+ static auto const builtin_cmsg_space =
+ CMSG_SPACE(builtin_n_fds * sizeof(int));
+ auto const fds_bytes = fds.size() * sizeof(int);
+ VariableLengthArray<builtin_cmsg_space> control{CMSG_SPACE(fds_bytes)};
+ // Silence valgrind uninitialized memory complaint
+ memset(control.data(), 0, control.size());
+
+ // Message to send
+ struct msghdr header;
+ header.msg_name = NULL;
+ header.msg_namelen = 0;
+ header.msg_iov = &iov;
+ header.msg_iovlen = 1;
+ header.msg_controllen = control.size();
+ header.msg_control = control.data();
+ header.msg_flags = 0;
+
+ // Control message contains file descriptors
+ struct cmsghdr* message = CMSG_FIRSTHDR(&header);
+ message->cmsg_len = CMSG_LEN(fds_bytes);
+ message->cmsg_level = SOL_SOCKET;
+ message->cmsg_type = SCM_RIGHTS;
+
+ int* const data = reinterpret_cast<int*>(CMSG_DATA(message));
+ int i = 0;
+ for (auto& fd : fds) data[i++] = fd;
+
+ auto const sent = sendmsg(socket, &header, MSG_NOSIGNAL);
+ if (sent < 0)
+ BOOST_THROW_EXCEPTION(std::runtime_error("Failed to send fds: " +
+ std::string(strerror(errno))));
+ }
+}
+
+bool socket_error_is_transient(int error_code) { return (error_code == EINTR); }
+
+void receive_data(Fd const& socket, void* buffer, size_t bytes_requested,
+ std::vector<Fd>& fds) {
+ if (bytes_requested == 0)
+ BOOST_THROW_EXCEPTION(std::logic_error("Attempted to receive 0 bytes"));
+
+ size_t bytes_read{0};
+ unsigned fds_read{0};
+ while (bytes_read < bytes_requested) {
+ // Store the data in the buffer requested
+ struct iovec iov;
+ iov.iov_base = static_cast<uint8_t*>(buffer) + bytes_read;
+ iov.iov_len = bytes_requested - bytes_read;
+
+ // Allocate space for control message
+ static auto const builtin_n_fds = 5;
+ static auto const builtin_cmsg_space =
+ CMSG_SPACE(builtin_n_fds * sizeof(int));
+ auto const fds_bytes = (fds.size() - fds_read) * sizeof(int);
+ VariableLengthArray<builtin_cmsg_space> control{CMSG_SPACE(fds_bytes)};
+
+ // Message to read
+ struct msghdr header;
+ header.msg_name = NULL;
+ header.msg_namelen = 0;
+ header.msg_iov = &iov;
+ header.msg_iovlen = 1;
+ header.msg_controllen = control.size();
+ header.msg_control = control.data();
+ header.msg_flags = 0;
+
+ ssize_t const result = recvmsg(socket, &header, MSG_NOSIGNAL | MSG_WAITALL);
+ if (result == 0)
+ BOOST_THROW_EXCEPTION(socket_disconnected_error(
+ "Failed to read message from server: server has shutdown"));
+ if (result < 0) {
+ if (socket_error_is_transient(errno)) continue;
+ if (errno == EAGAIN) continue;
+ if (errno == EPIPE)
+ BOOST_THROW_EXCEPTION(
+ boost::enable_error_info(
+ socket_disconnected_error("Failed to read message from server"))
+ << boost::errinfo_errno(errno));
+
+ BOOST_THROW_EXCEPTION(boost::enable_error_info(socket_error(
+ "Failed to read message from server"))
+ << boost::errinfo_errno(errno));
+ }
+
+ bytes_read += result;
+
+ // If we get a proper control message, copy the received
+ // file descriptors back to the caller
+ struct cmsghdr const* const cmsg = CMSG_FIRSTHDR(&header);
+ if (cmsg) {
+ if ((cmsg->cmsg_level == SOL_SOCKET) &&
+ (cmsg->cmsg_type == SCM_CREDENTIALS))
+ BOOST_THROW_EXCEPTION(
+ fd_reception_error("received SCM_CREDENTIALS when expecting fd"));
+ if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
+ BOOST_THROW_EXCEPTION(fd_reception_error(
+ "Invalid control message for receiving file descriptors"));
+
+ int const* const data = reinterpret_cast<int const*> CMSG_DATA(cmsg);
+ ptrdiff_t const header_size = reinterpret_cast<char const*>(data) -
+ reinterpret_cast<char const*>(cmsg);
+ int const nfds = (cmsg->cmsg_len - header_size) / sizeof(int);
+
+ // NOTE: This relies on the file descriptor cmsg being read
+ // (and written) atomically.
+ if (cmsg->cmsg_len > CMSG_LEN(fds_bytes) ||
+ (header.msg_flags & MSG_CTRUNC)) {
+ for (int i = 0; i < nfds; i++) ::close(data[i]);
+ BOOST_THROW_EXCEPTION(
+ std::runtime_error("Received more fds than expected"));
+ }
+
+ // We can't properly pass Fds through google::protobuf::Message,
+ // which is where these get shoved.
+ //
+ // When we have our own RPC generator plugin and aren't using deprecated
+ // Protobuf features this can go away.
+ for (int i = 0; i < nfds; i++)
+ fds[fds_read + i] = Fd{IntOwnedFd{data[i]}};
+
+ fds_read += nfds;
+ }
+ }
+
+ if (fds_read < fds.size()) {
+ for (auto fd : fds)
+ if (fd >= 0) ::close(fd);
+ fds.clear();
+ BOOST_THROW_EXCEPTION(
+ std::runtime_error("Received fewer fds than expected"));
+ }
+}
+} // namespace anbox
Code Review / iec.git / blobdiff