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// Copyright 2020 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#include "pw_stream/socket_stream.h"
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <cerrno>
#include <cstring>
#include "pw_assert/check.h"
#include "pw_log/log.h"
#include "pw_string/to_string.h"
namespace pw::stream {
namespace {
constexpr uint32_t kServerBacklogLength = 1;
constexpr const char* kLocalhostAddress = "127.0.0.1";
// Set necessary options on a socket file descriptor.
void ConfigureSocket([[maybe_unused]] int socket) {
#if defined(__APPLE__)
// Use SO_NOSIGPIPE to avoid getting a SIGPIPE signal when the remote peer
// drops the connection. This is supported on macOS only.
constexpr int value = 1;
if (setsockopt(socket, SOL_SOCKET, SO_NOSIGPIPE, &value, sizeof(int)) < 0) {
PW_LOG_WARN("Failed to set SO_NOSIGPIPE: %s", std::strerror(errno));
}
#endif // defined(__APPLE__)
}
} // namespace
// TODO(b/240982565): Implement SocketStream for Windows.
Status SocketStream::SocketStream::Connect(const char* host, uint16_t port) {
if (host == nullptr || std::strcmp(host, "localhost") == 0) {
host = kLocalhostAddress;
}
struct addrinfo hints = {};
struct addrinfo* res;
char port_buffer[6];
PW_CHECK(ToString(port, port_buffer).ok());
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV | AI_PASSIVE;
if (getaddrinfo(host, port_buffer, &hints, &res) != 0) {
PW_LOG_ERROR("Failed to configure connection address for socket");
return Status::InvalidArgument();
}
connection_fd_ = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
ConfigureSocket(connection_fd_);
if (connect(connection_fd_, res->ai_addr, res->ai_addrlen) < 0) {
close(connection_fd_);
connection_fd_ = kInvalidFd;
}
freeaddrinfo(res);
if (connection_fd_ == kInvalidFd) {
PW_LOG_ERROR(
"Failed to connect to %s:%d: %s", host, port, std::strerror(errno));
return Status::Unknown();
}
return OkStatus();
}
void SocketStream::Close() {
if (connection_fd_ != kInvalidFd) {
close(connection_fd_);
connection_fd_ = kInvalidFd;
}
}
Status SocketStream::DoWrite(span<const std::byte> data) {
int send_flags = 0;
#if defined(__linux__)
// Use MSG_NOSIGNAL to avoid getting a SIGPIPE signal when the remote
// peer drops the connection. This is supported on Linux only.
send_flags |= MSG_NOSIGNAL;
#endif // defined(__linux__)
ssize_t bytes_sent =
send(connection_fd_, data.data(), data.size_bytes(), send_flags);
if (bytes_sent < 0 || static_cast<size_t>(bytes_sent) != data.size()) {
if (errno == EPIPE) {
// An EPIPE indicates that the connection is closed. Return an OutOfRange
// error.
return Status::OutOfRange();
}
return Status::Unknown();
}
return OkStatus();
}
StatusWithSize SocketStream::DoRead(ByteSpan dest) {
ssize_t bytes_rcvd = recv(connection_fd_, dest.data(), dest.size_bytes(), 0);
if (bytes_rcvd == 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK) {
// Socket timed out when trying to read.
// This should only occur if SO_RCVTIMEO was configured to be nonzero, or
// if the socket was opened with the O_NONBLOCK flag to prevent any
// blocking when performing reads or writes.
return StatusWithSize::ResourceExhausted();
}
// Remote peer has closed the connection.
Close();
return StatusWithSize::OutOfRange();
} else if (bytes_rcvd < 0) {
return StatusWithSize::Unknown();
}
return StatusWithSize(bytes_rcvd);
}
// Listen for connections on the given port.
// If port is 0, a random unused port is chosen and can be retrieved with
// port().
Status ServerSocket::Listen(uint16_t port) {
socket_fd_ = socket(AF_INET6, SOCK_STREAM, 0);
if (socket_fd_ == kInvalidFd) {
return Status::Unknown();
}
// Allow binding to an address that may still be in use by a closed socket.
constexpr int value = 1;
setsockopt(socket_fd_, SOL_SOCKET, SO_REUSEADDR, &value, sizeof(int));
if (port != 0) {
struct sockaddr_in6 addr = {};
socklen_t addr_len = sizeof(addr);
addr.sin6_family = AF_INET6;
addr.sin6_port = htons(port);
addr.sin6_addr = in6addr_any;
if (bind(socket_fd_, reinterpret_cast<sockaddr*>(&addr), addr_len) < 0) {
return Status::Unknown();
}
}
if (listen(socket_fd_, kServerBacklogLength) < 0) {
return Status::Unknown();
}
// Find out which port the socket is listening on, and fill in port_.
struct sockaddr_in6 addr = {};
socklen_t addr_len = sizeof(addr);
if (getsockname(socket_fd_, reinterpret_cast<sockaddr*>(&addr), &addr_len) <
0 ||
static_cast<size_t>(addr_len) > sizeof(addr)) {
close(socket_fd_);
return Status::Unknown();
}
port_ = ntohs(addr.sin6_port);
return OkStatus();
}
// Accept a connection. Blocks until after a client is connected.
// On success, returns a SocketStream connected to the new client.
Result<SocketStream> ServerSocket::Accept() {
struct sockaddr_in6 sockaddr_client_ = {};
socklen_t len = sizeof(sockaddr_client_);
int connection_fd =
accept(socket_fd_, reinterpret_cast<sockaddr*>(&sockaddr_client_), &len);
if (connection_fd == kInvalidFd) {
return Status::Unknown();
}
ConfigureSocket(connection_fd);
SocketStream client_stream;
client_stream.connection_fd_ = connection_fd;
return client_stream;
}
// Close the server socket, preventing further connections.
void ServerSocket::Close() {
if (socket_fd_ != kInvalidFd) {
close(socket_fd_);
socket_fd_ = kInvalidFd;
}
}
} // namespace pw::stream
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