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/*
* Copyright (C) 2015 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.
*/
#if !ADB_HOST
#define TRACE_TAG JDWP
#include "sysdeps.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <list>
#include <memory>
#include <thread>
#include <vector>
#include <adbconnection/server.h>
#include <android-base/cmsg.h>
#include <android-base/unique_fd.h>
#include "adb.h"
#include "adb_io.h"
#include "adb_unique_fd.h"
#include "adb_utils.h"
using android::base::borrowed_fd;
using android::base::unique_fd;
/* here's how these things work.
when adbd starts, it creates a unix server socket
named @jdwp-control (@ is a shortcut for "first byte is zero"
to use the private namespace instead of the file system)
when a new JDWP daemon thread starts in a new VM process, it creates
a connection to @jdwp-control to announce its availability.
JDWP thread @jdwp-control
| |
|-------------------------------> |
| hello I'm in process <pid> |
| |
| |
the connection is kept alive. it will be closed automatically if
the JDWP process terminates (this allows adbd to detect dead
processes).
adbd thus maintains a list of "active" JDWP processes. it can send
its content to clients through the "device:debug-ports" service,
or even updates through the "device:track-debug-ports" service.
when a debugger wants to connect, it simply runs the command
equivalent to "adb forward tcp:<hostport> jdwp:<pid>"
"jdwp:<pid>" is a new forward destination format used to target
a given JDWP process on the device. when sutch a request arrives,
adbd does the following:
- first, it calls socketpair() to create a pair of equivalent
sockets.
- it attaches the first socket in the pair to a local socket
which is itself attached to the transport's remote socket:
- it sends the file descriptor of the second socket directly
to the JDWP process with the help of sendmsg()
JDWP thread @jdwp-control
| |
| <----------------------|
| OK, try this file descriptor |
| |
| |
then, the JDWP thread uses this new socket descriptor as its
pass-through connection to the debugger (and receives the
JDWP-Handshake message, answers to it, etc...)
this gives the following graphics:
____________________________________
| |
| ADB Server (host) |
| |
Debugger <---> LocalSocket <----> RemoteSocket |
| ^^ |
|___________________________||_______|
||
Transport ||
(TCP for emulator - USB for device) ||
||
___________________________||_______
| || |
| ADBD (device) || |
| VV |
JDWP <======> LocalSocket <----> RemoteSocket |
| |
|____________________________________|
due to the way adb works, this doesn't need a special socket
type or fancy handling of socket termination if either the debugger
or the JDWP process closes the connection.
THIS IS THE SIMPLEST IMPLEMENTATION I COULD FIND, IF YOU HAPPEN
TO HAVE A BETTER IDEA, LET ME KNOW - Digit
**********************************************************************/
/** JDWP PID List Support Code
** for each JDWP process, we record its pid and its connected socket
**/
static void jdwp_process_event(int socket, unsigned events, void* _proc);
static void jdwp_process_list_updated(void);
struct JdwpProcess;
static auto& _jdwp_list = *new std::list<std::unique_ptr<JdwpProcess>>();
struct JdwpProcess {
JdwpProcess(unique_fd socket, pid_t pid) {
CHECK(pid != 0);
this->socket = socket;
this->pid = pid;
this->fde = fdevent_create(socket.release(), jdwp_process_event, this);
if (!this->fde) {
LOG(FATAL) << "could not create fdevent for new JDWP process";
}
}
~JdwpProcess() {
if (this->socket >= 0) {
adb_shutdown(this->socket);
this->socket = -1;
}
if (this->fde) {
fdevent_destroy(this->fde);
this->fde = nullptr;
}
out_fds.clear();
}
void RemoveFromList() {
auto pred = [this](const auto& proc) { return proc.get() == this; };
_jdwp_list.remove_if(pred);
}
borrowed_fd socket = -1;
int32_t pid = -1;
fdevent* fde = nullptr;
std::vector<unique_fd> out_fds;
};
static size_t jdwp_process_list(char* buffer, size_t bufferlen) {
std::string temp;
for (auto& proc : _jdwp_list) {
std::string next = std::to_string(proc->pid) + "\n";
if (temp.length() + next.length() > bufferlen) {
D("truncating JDWP process list (max len = %zu)", bufferlen);
break;
}
temp.append(next);
}
memcpy(buffer, temp.data(), temp.length());
return temp.length();
}
static size_t jdwp_process_list_msg(char* buffer, size_t bufferlen) {
// Message is length-prefixed with 4 hex digits in ASCII.
static constexpr size_t header_len = 4;
if (bufferlen < header_len) {
LOG(FATAL) << "invalid JDWP process list buffer size: " << bufferlen;
}
char head[header_len + 1];
size_t len = jdwp_process_list(buffer + header_len, bufferlen - header_len);
snprintf(head, sizeof head, "%04zx", len);
memcpy(buffer, head, header_len);
return len + header_len;
}
static void jdwp_process_event(int socket, unsigned events, void* _proc) {
JdwpProcess* proc = reinterpret_cast<JdwpProcess*>(_proc);
CHECK_EQ(socket, proc->socket.get());
if (events & FDE_READ) {
// We already have the PID, if we can read from the socket, we've probably hit EOF.
D("terminating JDWP connection %d", proc->pid);
goto CloseProcess;
}
if (events & FDE_WRITE) {
D("trying to send fd to JDWP process (count = %zu)", proc->out_fds.size());
CHECK(!proc->out_fds.empty());
int fd = proc->out_fds.back().get();
if (android::base::SendFileDescriptors(socket, "", 1, fd) != 1) {
D("sending new file descriptor to JDWP %d failed: %s", proc->pid, strerror(errno));
goto CloseProcess;
}
D("sent file descriptor %d to JDWP process %d", fd, proc->pid);
proc->out_fds.pop_back();
if (proc->out_fds.empty()) {
fdevent_del(proc->fde, FDE_WRITE);
}
}
return;
CloseProcess:
proc->RemoveFromList();
jdwp_process_list_updated();
}
unique_fd create_jdwp_connection_fd(int pid) {
D("looking for pid %d in JDWP process list", pid);
for (auto& proc : _jdwp_list) {
if (proc->pid == pid) {
int fds[2];
if (adb_socketpair(fds) < 0) {
D("%s: socket pair creation failed: %s", __FUNCTION__, strerror(errno));
return unique_fd{};
}
D("socketpair: (%d,%d)", fds[0], fds[1]);
proc->out_fds.emplace_back(fds[1]);
if (proc->out_fds.size() == 1) {
fdevent_add(proc->fde, FDE_WRITE);
}
return unique_fd{fds[0]};
}
}
D("search failed !!");
return unique_fd{};
}
/** "jdwp" local service implementation
** this simply returns the list of known JDWP process pids
**/
struct JdwpSocket : public asocket {
bool pass = false;
};
static void jdwp_socket_close(asocket* s) {
D("LS(%d): closing jdwp socket", s->id);
if (s->peer) {
D("LS(%d) peer->close()ing peer->id=%d peer->fd=%d", s->id, s->peer->id, s->peer->fd);
s->peer->peer = nullptr;
s->peer->close(s->peer);
s->peer = nullptr;
}
remove_socket(s);
delete s;
}
static int jdwp_socket_enqueue(asocket* s, apacket::payload_type) {
/* you can't write to this asocket */
D("LS(%d): JDWP socket received data?", s->id);
s->peer->close(s->peer);
return -1;
}
static void jdwp_socket_ready(asocket* s) {
JdwpSocket* jdwp = (JdwpSocket*)s;
asocket* peer = jdwp->peer;
/* on the first call, send the list of pids,
* on the second one, close the connection
*/
if (!jdwp->pass) {
apacket::payload_type data;
data.resize(s->get_max_payload());
size_t len = jdwp_process_list(&data[0], data.size());
data.resize(len);
peer->enqueue(peer, std::move(data));
jdwp->pass = true;
} else {
peer->close(peer);
}
}
asocket* create_jdwp_service_socket(void) {
JdwpSocket* s = new JdwpSocket();
if (!s) {
LOG(FATAL) << "failed to allocate JdwpSocket";
}
install_local_socket(s);
s->ready = jdwp_socket_ready;
s->enqueue = jdwp_socket_enqueue;
s->close = jdwp_socket_close;
s->pass = false;
return s;
}
/** "track-jdwp" local service implementation
** this periodically sends the list of known JDWP process pids
** to the client...
**/
struct JdwpTracker : public asocket {
bool need_initial;
};
static auto& _jdwp_trackers = *new std::vector<std::unique_ptr<JdwpTracker>>();
static void jdwp_process_list_updated(void) {
std::string data;
data.resize(1024);
data.resize(jdwp_process_list_msg(&data[0], data.size()));
for (auto& t : _jdwp_trackers) {
if (t->peer) {
// The tracker might not have been connected yet.
apacket::payload_type payload(data.begin(), data.end());
t->peer->enqueue(t->peer, std::move(payload));
}
}
}
static void jdwp_tracker_close(asocket* s) {
D("LS(%d): destroying jdwp tracker service", s->id);
if (s->peer) {
D("LS(%d) peer->close()ing peer->id=%d peer->fd=%d", s->id, s->peer->id, s->peer->fd);
s->peer->peer = nullptr;
s->peer->close(s->peer);
s->peer = nullptr;
}
remove_socket(s);
auto pred = [s](const auto& tracker) { return tracker.get() == s; };
_jdwp_trackers.erase(std::remove_if(_jdwp_trackers.begin(), _jdwp_trackers.end(), pred),
_jdwp_trackers.end());
}
static void jdwp_tracker_ready(asocket* s) {
JdwpTracker* t = (JdwpTracker*)s;
if (t->need_initial) {
apacket::payload_type data;
data.resize(s->get_max_payload());
data.resize(jdwp_process_list_msg(&data[0], data.size()));
t->need_initial = false;
s->peer->enqueue(s->peer, std::move(data));
}
}
static int jdwp_tracker_enqueue(asocket* s, apacket::payload_type) {
/* you can't write to this socket */
D("LS(%d): JDWP tracker received data?", s->id);
s->peer->close(s->peer);
return -1;
}
asocket* create_jdwp_tracker_service_socket(void) {
auto t = std::make_unique<JdwpTracker>();
if (!t) {
LOG(FATAL) << "failed to allocate JdwpTracker";
}
memset(t.get(), 0, sizeof(asocket));
install_local_socket(t.get());
D("LS(%d): created new jdwp tracker service", t->id);
t->ready = jdwp_tracker_ready;
t->enqueue = jdwp_tracker_enqueue;
t->close = jdwp_tracker_close;
t->need_initial = true;
asocket* result = t.get();
_jdwp_trackers.emplace_back(std::move(t));
return result;
}
int init_jdwp(void) {
std::thread([]() {
adb_thread_setname("jdwp control");
adbconnection_listen([](int fd, pid_t pid) {
LOG(INFO) << "jdwp connection from " << pid;
fdevent_run_on_main_thread([fd, pid] {
unique_fd ufd(fd);
auto proc = std::make_unique<JdwpProcess>(std::move(ufd), pid);
if (!proc) {
LOG(FATAL) << "failed to allocate JdwpProcess";
}
_jdwp_list.emplace_back(std::move(proc));
jdwp_process_list_updated();
});
});
}).detach();
return 0;
}
#endif /* !ADB_HOST */