/*
* 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 <vector>
#include "adb.h"
#include "adb_io.h"
#include "adb_unique_fd.h"
#include "adb_utils.h"
/* 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
**/
// PIDs are transmitted as 4 hex digits in ascii.
static constexpr size_t PID_LEN = 4;
static void jdwp_process_event(int socket, unsigned events, void* _proc);
static void jdwp_process_list_updated(void);
struct JdwpProcess;
static std::list<std::unique_ptr<JdwpProcess>> _jdwp_list;
struct JdwpProcess {
explicit JdwpProcess(int socket) {
this->socket = socket;
this->fde = fdevent_create(socket, jdwp_process_event, this);
if (!this->fde) {
fatal("could not create fdevent for new JDWP process");
}
this->fde->state |= FDE_DONT_CLOSE;
/* start by waiting for the PID */
fdevent_add(this->fde, FDE_READ);
}
~JdwpProcess() {
if (this->socket >= 0) {
adb_shutdown(this->socket);
adb_close(this->socket);
this->socket = -1;
}
if (this->fde) {
fdevent_destroy(this->fde);
this->fde = nullptr;
}
out_fds.clear();
}
void RemoveFromList() {
if (this->pid >= 0) {
D("removing pid %d from jdwp process list", this->pid);
} else {
D("removing transient JdwpProcess from list");
}
auto pred = [this](const auto& proc) { return proc.get() == this; };
_jdwp_list.remove_if(pred);
}
int pid = -1;
int socket = -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) {
/* skip transient connections */
if (proc->pid < 0) {
continue;
}
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) {
fatal("invalid JDWP process list buffer size: %zu", 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);
if (events & FDE_READ) {
if (proc->pid < 0) {
/* read the PID as a 4-hexchar string */
char buf[PID_LEN + 1];
ssize_t rc = TEMP_FAILURE_RETRY(recv(socket, buf, PID_LEN, 0));
if (rc != PID_LEN) {
D("failed to read jdwp pid: %s", strerror(errno));
goto CloseProcess;
}
buf[PID_LEN] = '\0';
if (sscanf(buf, "%04x", &proc->pid) != 1) {
D("could not decode JDWP %p PID number: '%s'", proc, buf);
goto CloseProcess;
}
/* all is well, keep reading to detect connection closure */
D("Adding pid %d to jdwp process list", proc->pid);
jdwp_process_list_updated();
} else {
/* the pid was read, if we get there it's probably because the connection
* was closed (e.g. the JDWP process exited or crashed) */
char buf[32];
while (true) {
int len = TEMP_FAILURE_RETRY(recv(socket, buf, sizeof(buf), 0));
if (len == 0) {
D("terminating JDWP %d connection: EOF", proc->pid);
break;
} else if (len < 0) {
if (len < 0 && errno == EAGAIN) {
return;
}
D("terminating JDWP %d connection: EOF", proc->pid);
break;
} else {
D("ignoring unexpected JDWP %d control socket activity (%d bytes)", proc->pid,
len);
}
}
goto CloseProcess;
}
}
if (events & FDE_WRITE) {
D("trying to send fd to JDWP process (count = %zu)", proc->out_fds.size());
if (!proc->out_fds.empty()) {
int fd = proc->out_fds.back().get();
struct cmsghdr* cmsg;
struct msghdr msg;
struct iovec iov;
char dummy = '!';
char buffer[sizeof(struct cmsghdr) + sizeof(int)];
iov.iov_base = &dummy;
iov.iov_len = 1;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_flags = 0;
msg.msg_control = buffer;
msg.msg_controllen = sizeof(buffer);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = msg.msg_controllen;
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
((int*)CMSG_DATA(cmsg))[0] = fd;
if (!set_file_block_mode(proc->socket, true)) {
VLOG(JDWP) << "failed to set blocking mode for fd " << proc->socket;
goto CloseProcess;
}
int ret = TEMP_FAILURE_RETRY(sendmsg(proc->socket, &msg, 0));
if (ret < 0) {
D("sending new file descriptor to JDWP %d failed: %s", proc->pid, strerror(errno));
goto CloseProcess;
}
adb_close(fd);
D("sent file descriptor %d to JDWP process %d", fd, proc->pid);
proc->out_fds.pop_back();
if (!set_file_block_mode(proc->socket, false)) {
VLOG(JDWP) << "failed to set non-blocking mode for fd " << proc->socket;
goto CloseProcess;
}
if (proc->out_fds.empty()) {
fdevent_del(proc->fde, FDE_WRITE);
}
}
}
return;
CloseProcess:
proc->RemoveFromList();
jdwp_process_list_updated();
}
int 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 -1;
}
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 fds[0];
}
}
D("search failed !!");
return -1;
}
/** VM DEBUG CONTROL SOCKET
**
** we do implement a custom asocket to receive the data
**/
/* name of the debug control Unix socket */
#define JDWP_CONTROL_NAME "\0jdwp-control"
#define JDWP_CONTROL_NAME_LEN (sizeof(JDWP_CONTROL_NAME) - 1)
struct JdwpControl {
int listen_socket;
fdevent* fde;
};
static JdwpControl _jdwp_control;
static void jdwp_control_event(int s, unsigned events, void* user);
static int jdwp_control_init(JdwpControl* control, const char* sockname, int socknamelen) {
sockaddr_un addr;
socklen_t addrlen;
int s;
int maxpath = sizeof(addr.sun_path);
int pathlen = socknamelen;
if (pathlen >= maxpath) {
D("vm debug control socket name too long (%d extra chars)", pathlen + 1 - maxpath);
return -1;
}
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
memcpy(addr.sun_path, sockname, socknamelen);
s = socket(AF_UNIX, SOCK_SEQPACKET | SOCK_CLOEXEC, 0);
if (s < 0) {
D("could not create vm debug control socket. %d: %s", errno, strerror(errno));
return -1;
}
addrlen = pathlen + sizeof(addr.sun_family);
if (bind(s, reinterpret_cast<sockaddr*>(&addr), addrlen) < 0) {
D("could not bind vm debug control socket: %d: %s", errno, strerror(errno));
adb_close(s);
return -1;
}
if (listen(s, 4) < 0) {
D("listen failed in jdwp control socket: %d: %s", errno, strerror(errno));
adb_close(s);
return -1;
}
control->listen_socket = s;
control->fde = fdevent_create(s, jdwp_control_event, control);
if (control->fde == NULL) {
D("could not create fdevent for jdwp control socket");
adb_close(s);
return -1;
}
/* only wait for incoming connections */
fdevent_add(control->fde, FDE_READ);
D("jdwp control socket started (%d)", control->listen_socket);
return 0;
}
static void jdwp_control_event(int s, unsigned events, void* _control) {
JdwpControl* control = (JdwpControl*)_control;
if (events & FDE_READ) {
int s = adb_socket_accept(control->listen_socket, nullptr, nullptr);
if (s < 0) {
if (errno == ECONNABORTED) {
/* oops, the JDWP process died really quick */
D("oops, the JDWP process died really quick");
return;
} else {
/* the socket is probably closed ? */
D("weird accept() failed on jdwp control socket: %s", strerror(errno));
return;
}
}
auto proc = std::make_unique<JdwpProcess>(s);
if (!proc) {
fatal("failed to allocate JdwpProcess");
}
_jdwp_list.emplace_back(std::move(proc));
}
}
/** "jdwp" local service implementation
** this simply returns the list of known JDWP process pids
**/
struct JdwpSocket : public asocket {
bool pass;
};
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);
free(s);
}
static int jdwp_socket_enqueue(asocket* s, apacket* p) {
/* you can't write to this asocket */
D("LS(%d): JDWP socket received data?", s->id);
put_apacket(p);
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* p = get_apacket();
p->len = jdwp_process_list((char*)p->data, s->get_max_payload());
peer->enqueue(peer, p);
jdwp->pass = true;
} else {
peer->close(peer);
}
}
asocket* create_jdwp_service_socket(void) {
JdwpSocket* s = reinterpret_cast<JdwpSocket*>(calloc(sizeof(*s), 1));
if (!s) {
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 std::vector<std::unique_ptr<JdwpTracker>> _jdwp_trackers;
static void jdwp_process_list_updated(void) {
char buffer[1024];
int len = jdwp_process_list_msg(buffer, sizeof(buffer));
for (auto& t : _jdwp_trackers) {
apacket* p = get_apacket();
memcpy(p->data, buffer, len);
p->len = len;
if (t->peer) {
// The tracker might not have been connected yet.
t->peer->enqueue(t->peer, p);
}
}
}
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* p = get_apacket();
t->need_initial = false;
p->len = jdwp_process_list_msg((char*)p->data, s->get_max_payload());
s->peer->enqueue(s->peer, p);
}
}
static int jdwp_tracker_enqueue(asocket* s, apacket* p) {
/* you can't write to this socket */
D("LS(%d): JDWP tracker received data?", s->id);
put_apacket(p);
s->peer->close(s->peer);
return -1;
}
asocket* create_jdwp_tracker_service_socket(void) {
auto t = std::make_unique<JdwpTracker>();
if (!t) {
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) {
return jdwp_control_init(&_jdwp_control, JDWP_CONTROL_NAME, JDWP_CONTROL_NAME_LEN);
}
#endif /* !ADB_HOST */