/*
* Copyright (C) 2008 The Android Open Source Project
*
* 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
*
* http://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 <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include "android-base/stringprintf.h"
#include "base/logging.h" // For VLOG.
#include "jdwp/jdwp_priv.h"
namespace art {
namespace JDWP {
static constexpr uint16_t kBasePort = 8000;
static constexpr uint16_t kMaxPort = 8040;
/*
* JDWP network state.
*
* We only talk to one debugger at a time.
*/
struct JdwpSocketState : public JdwpNetStateBase {
uint16_t listenPort;
int listenSock; /* listen for connection from debugger */
explicit JdwpSocketState(JdwpState* state)
: JdwpNetStateBase(state),
listenPort(0U),
listenSock(-1),
remote_port_(0U) {
}
virtual bool Accept();
virtual bool Establish(const JdwpOptions*);
virtual void Shutdown();
virtual bool ProcessIncoming();
private:
in_addr remote_addr_;
uint16_t remote_port_;
};
static JdwpSocketState* SocketStartup(JdwpState* state, uint16_t port, bool probe);
/*
* Set up some stuff for transport=dt_socket.
*/
bool InitSocketTransport(JdwpState* state, const JdwpOptions* options) {
uint16_t port = options->port;
if (options->server) {
if (options->port != 0) {
/* try only the specified port */
state->netState = SocketStartup(state, port, false);
} else {
/* scan through a range of ports, binding to the first available */
for (port = kBasePort; port <= kMaxPort; port++) {
state->netState = SocketStartup(state, port, true);
if (state->netState != nullptr) {
break;
}
}
}
if (state->netState == nullptr) {
LOG(ERROR) << "JDWP net startup failed (req port=" << options->port << ")";
return false;
}
} else {
state->netState = SocketStartup(state, 0, false);
}
if (options->suspend) {
LOG(INFO) << "JDWP will wait for debugger on port " << port;
} else {
LOG(INFO) << "JDWP will " << (options->server ? "listen" : "connect") << " on port " << port;
}
return true;
}
/*
* Initialize JDWP stuff.
*
* Allocates a new state structure. If "port" is non-zero, this also
* tries to bind to a listen port. If "port" is zero, we assume
* we're preparing for an outbound connection, and return without binding
* to anything.
*
* This may be called several times if we're probing for a port.
*
* Returns 0 on success.
*/
static JdwpSocketState* SocketStartup(JdwpState* state, uint16_t port, bool probe) {
JdwpSocketState* netState = new JdwpSocketState(state);
if (port == 0) {
return netState;
}
netState->listenSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (netState->listenSock < 0) {
PLOG(probe ? ::android::base::ERROR : ::android::base::FATAL) << "Socket create failed";
goto fail;
}
/* allow immediate re-use */
{
int one = 1;
if (setsockopt(netState->listenSock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0) {
PLOG(probe ? ::android::base::ERROR : ::android::base::FATAL)
<< "setsockopt(SO_REUSEADDR) failed";
goto fail;
}
}
union {
sockaddr_in addrInet;
sockaddr addrPlain;
} addr;
addr.addrInet.sin_family = AF_INET;
addr.addrInet.sin_port = htons(port);
inet_aton("127.0.0.1", &addr.addrInet.sin_addr);
if (bind(netState->listenSock, &addr.addrPlain, sizeof(addr)) != 0) {
PLOG(probe ? ::android::base::ERROR : ::android::base::FATAL)
<< "Attempt to bind to port " << port << " failed";
goto fail;
}
netState->listenPort = port;
if (listen(netState->listenSock, 5) != 0) {
PLOG(probe ? ::android::base::ERROR : ::android::base::FATAL) << "Listen failed";
goto fail;
}
return netState;
fail:
netState->Shutdown();
delete netState;
return nullptr;
}
/*
* Shut down JDWP listener. Don't free state.
*
* This may be called from a non-JDWP thread as part of shutting the
* JDWP thread down.
*
* (This is currently called several times during startup as we probe
* for an open port.)
*/
void JdwpSocketState::Shutdown() {
int local_listenSock = this->listenSock;
int local_clientSock = this->clientSock;
/* clear these out so it doesn't wake up and try to reuse them */
this->listenSock = this->clientSock = -1;
/* "shutdown" dislodges blocking read() and accept() calls */
if (local_listenSock != -1) {
shutdown(local_listenSock, SHUT_RDWR);
close(local_listenSock);
}
if (local_clientSock != -1) {
shutdown(local_clientSock, SHUT_RDWR);
close(local_clientSock);
}
WakePipe();
}
/*
* Disable the TCP Nagle algorithm, which delays transmission of outbound
* packets until the previous transmissions have been acked. JDWP does a
* lot of back-and-forth with small packets, so this may help.
*/
static int SetNoDelay(int fd) {
int on = 1;
int cc = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
CHECK_EQ(cc, 0);
return cc;
}
/*
* Accept a connection. This will block waiting for somebody to show up.
* If that's not desirable, use checkConnection() to make sure something
* is pending.
*/
bool JdwpSocketState::Accept() {
union {
sockaddr_in addrInet;
sockaddr addrPlain;
} addr;
socklen_t addrlen;
int sock;
if (listenSock < 0) {
return false; /* you're not listening! */
}
CHECK_EQ(clientSock, -1); /* must not already be talking */
addrlen = sizeof(addr);
do {
sock = accept(listenSock, &addr.addrPlain, &addrlen);
if (sock < 0 && errno != EINTR) {
// When we call shutdown() on the socket, accept() returns with
// EINVAL. Don't gripe about it.
if (errno == EINVAL) {
if (VLOG_IS_ON(jdwp)) {
PLOG(ERROR) << "accept failed";
}
} else {
PLOG(ERROR) << "accept failed";
return false;
}
}
} while (sock < 0);
remote_addr_ = addr.addrInet.sin_addr;
remote_port_ = ntohs(addr.addrInet.sin_port);
VLOG(jdwp) << "+++ accepted connection from " << inet_ntoa(remote_addr_) << ":" << remote_port_;
clientSock = sock;
SetAwaitingHandshake(true);
input_count_ = 0;
VLOG(jdwp) << "Setting TCP_NODELAY on accepted socket";
SetNoDelay(clientSock);
if (!MakePipe()) {
return false;
}
return true;
}
/*
* Create a connection to a waiting debugger.
*/
bool JdwpSocketState::Establish(const JdwpOptions* options) {
union {
sockaddr_in addrInet;
sockaddr addrPlain;
} addr;
hostent* pEntry;
CHECK(!options->server);
CHECK(!options->host.empty());
CHECK_NE(options->port, 0);
/*
* Start by resolving the host name.
*/
#if defined(__linux__)
// Initial size of the work buffer used in gethostbyname_r.
//
// The call to gethostbyname_r below requires a user-allocated buffer,
// the size of which depends on the system. The initial implementation
// used to use a 128-byte buffer, but that was not enough on some
// systems (maybe because of IPv6), causing failures in JDWP host
// testing; thus it was increased to 256.
//
// However, we should not use a fixed size: gethostbyname_r's
// documentation states that if the work buffer is too small (i.e. if
// gethostbyname_r returns `ERANGE`), then the function should be
// called again with a bigger buffer. Which we do now, starting with
// an initial 256-byte buffer, and doubling it until gethostbyname_r
// accepts this size.
static constexpr size_t kInitialAuxBufSize = 256;
std::vector<char> auxBuf(kInitialAuxBufSize);
hostent he;
int error;
int cc;
while ((cc = gethostbyname_r(
options->host.c_str(), &he, auxBuf.data(), auxBuf.size(), &pEntry, &error))
== ERANGE) {
// The work buffer `auxBuf` is too small; enlarge it.
auxBuf.resize(auxBuf.size() * 2);
}
if (cc != 0 || pEntry == nullptr) {
LOG(WARNING) << "gethostbyname_r('" << options->host << "') failed: " << hstrerror(error);
return false;
}
#else
h_errno = 0;
pEntry = gethostbyname(options->host.c_str());
if (pEntry == nullptr) {
PLOG(WARNING) << "gethostbyname('" << options->host << "') failed";
return false;
}
#endif
/* copy it out ASAP to minimize risk of multithreaded annoyances */
memcpy(&addr.addrInet.sin_addr, pEntry->h_addr, pEntry->h_length);
addr.addrInet.sin_family = pEntry->h_addrtype;
addr.addrInet.sin_port = htons(options->port);
LOG(INFO) << "Connecting out to " << inet_ntoa(addr.addrInet.sin_addr) << ":"
<< ntohs(addr.addrInet.sin_port);
/*
* Create a socket.
*/
clientSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (clientSock < 0) {
PLOG(ERROR) << "Unable to create socket";
return false;
}
/*
* Try to connect.
*/
if (connect(clientSock, &addr.addrPlain, sizeof(addr)) != 0) {
PLOG(ERROR) << "Unable to connect to " << inet_ntoa(addr.addrInet.sin_addr) << ":"
<< ntohs(addr.addrInet.sin_port);
close(clientSock);
clientSock = -1;
return false;
}
LOG(INFO) << "Connection established to " << options->host << " ("
<< inet_ntoa(addr.addrInet.sin_addr) << ":" << ntohs(addr.addrInet.sin_port) << ")";
SetAwaitingHandshake(true);
input_count_ = 0;
SetNoDelay(clientSock);
if (!MakePipe()) {
return false;
}
return true;
}
/*
* Process incoming data. If no data is available, this will block until
* some arrives.
*
* If we get a full packet, handle it.
*
* To take some of the mystery out of life, we want to reject incoming
* connections if we already have a debugger attached. If we don't, the
* debugger will just mysteriously hang until it times out. We could just
* close the listen socket, but there's a good chance we won't be able to
* bind to the same port again, which would confuse utilities.
*
* Returns "false" on error (indicating that the connection has been severed),
* "true" if things are still okay.
*/
bool JdwpSocketState::ProcessIncoming() {
int readCount;
CHECK_NE(clientSock, -1);
if (!HaveFullPacket()) {
/* read some more, looping until we have data */
errno = 0;
while (1) {
int selCount;
fd_set readfds;
int maxfd = -1;
int fd;
FD_ZERO(&readfds);
/* configure fds; note these may get zapped by another thread */
fd = listenSock;
if (fd >= 0) {
FD_SET(fd, &readfds);
if (maxfd < fd) {
maxfd = fd;
}
}
fd = clientSock;
if (fd >= 0) {
FD_SET(fd, &readfds);
if (maxfd < fd) {
maxfd = fd;
}
}
fd = wake_pipe_[0];
if (fd >= 0) {
FD_SET(fd, &readfds);
if (maxfd < fd) {
maxfd = fd;
}
} else {
LOG(INFO) << "NOTE: entering select w/o wakepipe";
}
if (maxfd < 0) {
VLOG(jdwp) << "+++ all fds are closed";
return false;
}
/*
* Select blocks until it sees activity on the file descriptors.
* Closing the local file descriptor does not count as activity,
* so we can't rely on that to wake us up (it works for read()
* and accept(), but not select()).
*
* We can do one of three things: (1) send a signal and catch
* EINTR, (2) open an additional fd ("wake pipe") and write to
* it when it's time to exit, or (3) time out periodically and
* re-issue the select. We're currently using #2, as it's more
* reliable than #1 and generally better than #3. Wastes two fds.
*/
selCount = select(maxfd + 1, &readfds, nullptr, nullptr, nullptr);
if (selCount < 0) {
if (errno == EINTR) {
continue;
}
PLOG(ERROR) << "select failed";
goto fail;
}
if (wake_pipe_[0] >= 0 && FD_ISSET(wake_pipe_[0], &readfds)) {
if (listenSock >= 0) {
LOG(ERROR) << "Exit wake set, but not exiting?";
} else {
VLOG(jdwp) << "Got wake-up signal, bailing out of select";
}
goto fail;
}
if (listenSock >= 0 && FD_ISSET(listenSock, &readfds)) {
LOG(INFO) << "Ignoring second debugger -- accepting and dropping";
union {
sockaddr_in addrInet;
sockaddr addrPlain;
} addr;
socklen_t addrlen;
int tmpSock;
tmpSock = accept(listenSock, &addr.addrPlain, &addrlen);
if (tmpSock < 0) {
LOG(INFO) << "Weird -- accept failed";
} else {
close(tmpSock);
}
}
if (clientSock >= 0 && FD_ISSET(clientSock, &readfds)) {
readCount =
read(clientSock, input_buffer_ + input_count_, sizeof(input_buffer_) - input_count_);
if (readCount < 0) {
/* read failed */
if (errno != EINTR) {
goto fail;
}
VLOG(jdwp) << "+++ EINTR hit";
return true;
} else if (readCount == 0) {
/* EOF hit -- far end went away */
VLOG(jdwp) << "+++ peer disconnected";
goto fail;
} else {
break;
}
}
}
input_count_ += readCount;
if (!HaveFullPacket()) {
return true; /* still not there yet */
}
}
/*
* Special-case the initial handshake. For some bizarre reason we're
* expected to emulate bad tty settings by echoing the request back
* exactly as it was sent. Note the handshake is always initiated by
* the debugger, no matter who connects to whom.
*
* Other than this one case, the protocol [claims to be] stateless.
*/
if (IsAwaitingHandshake()) {
if (memcmp(input_buffer_, kMagicHandshake, kMagicHandshakeLen) != 0) {
LOG(ERROR) << android::base::StringPrintf("ERROR: bad handshake '%.14s'", input_buffer_);
goto fail;
}
errno = 0;
int cc = TEMP_FAILURE_RETRY(write(clientSock, input_buffer_, kMagicHandshakeLen));
if (cc != kMagicHandshakeLen) {
PLOG(ERROR) << "Failed writing handshake bytes ("
<< cc << " of " << kMagicHandshakeLen << ")";
goto fail;
}
ConsumeBytes(kMagicHandshakeLen);
SetAwaitingHandshake(false);
VLOG(jdwp) << "+++ handshake complete";
return true;
}
/*
* Handle this packet.
*/
return state_->HandlePacket();
fail:
Close();
return false;
}
} // namespace JDWP
} // namespace art