/* implement the "debug-ports" and "track-debug-ports" device services */
#include "sysdeps.h"
#define TRACE_TAG TRACE_JDWP
#include "adb.h"
#include <errno.h>
#include <stdio.h>
#include <string.h>
/* here's how these things work.
when adbd starts, it creates a unix server socket
named @vm-debug-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 @vm-debug-control to announce its availability.
JDWP thread @vm-debug-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 @vm-debug-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
**/
#define MAX_OUT_FDS 4
#if !ADB_HOST
#include <sys/socket.h>
#include <sys/un.h>
typedef struct JdwpProcess JdwpProcess;
struct JdwpProcess {
JdwpProcess* next;
JdwpProcess* prev;
int pid;
int socket;
fdevent* fde;
char in_buff[4]; /* input character to read PID */
int in_len; /* number from JDWP process */
int out_fds[MAX_OUT_FDS]; /* output array of file descriptors */
int out_count; /* to send to the JDWP process */
};
static JdwpProcess _jdwp_list;
static int
jdwp_process_list( char* buffer, int bufferlen )
{
char* end = buffer + bufferlen;
char* p = buffer;
JdwpProcess* proc = _jdwp_list.next;
for ( ; proc != &_jdwp_list; proc = proc->next ) {
int len;
/* skip transient connections */
if (proc->pid < 0)
continue;
len = snprintf(p, end-p, "%d\n", proc->pid);
if (p + len >= end)
break;
p += len;
}
p[0] = 0;
return (p - buffer);
}
static int
jdwp_process_list_msg( char* buffer, int bufferlen )
{
char head[5];
int len = jdwp_process_list( buffer+4, bufferlen-4 );
snprintf(head, sizeof head, "%04x", len);
memcpy(buffer, head, 4);
return len + 4;
}
static void jdwp_process_list_updated(void);
static void
jdwp_process_free( JdwpProcess* proc )
{
if (proc) {
int n;
proc->prev->next = proc->next;
proc->next->prev = proc->prev;
if (proc->socket >= 0) {
adb_shutdown(proc->socket);
adb_close(proc->socket);
proc->socket = -1;
}
if (proc->fde != NULL) {
fdevent_destroy(proc->fde);
proc->fde = NULL;
}
proc->pid = -1;
for (n = 0; n < proc->out_count; n++) {
adb_close(proc->out_fds[n]);
}
proc->out_count = 0;
free(proc);
jdwp_process_list_updated();
}
}
static void jdwp_process_event(int, unsigned, void*); /* forward */
static JdwpProcess*
jdwp_process_alloc( int socket )
{
JdwpProcess* proc = calloc(1,sizeof(*proc));
if (proc == NULL) {
D("not enough memory to create new JDWP process\n");
return NULL;
}
proc->socket = socket;
proc->pid = -1;
proc->next = proc;
proc->prev = proc;
proc->fde = fdevent_create( socket, jdwp_process_event, proc );
if (proc->fde == NULL) {
D("could not create fdevent for new JDWP process\n" );
free(proc);
return NULL;
}
proc->fde->state |= FDE_DONT_CLOSE;
proc->in_len = 0;
proc->out_count = 0;
/* append to list */
proc->next = &_jdwp_list;
proc->prev = proc->next->prev;
proc->prev->next = proc;
proc->next->prev = proc;
/* start by waiting for the PID */
fdevent_add(proc->fde, FDE_READ);
return proc;
}
static void
jdwp_process_event( int socket, unsigned events, void* _proc )
{
JdwpProcess* proc = _proc;
if (events & FDE_READ) {
if (proc->pid < 0) {
/* read the PID as a 4-hexchar string */
char* p = proc->in_buff + proc->in_len;
int size = 4 - proc->in_len;
char temp[5];
while (size > 0) {
int len = recv( socket, p, size, 0 );
if (len < 0) {
if (errno == EINTR)
continue;
if (errno == EAGAIN)
return;
/* this can fail here if the JDWP process crashes very fast */
D("weird unknown JDWP process failure: %s\n",
strerror(errno));
goto CloseProcess;
}
if (len == 0) { /* end of stream ? */
D("weird end-of-stream from unknown JDWP process\n");
goto CloseProcess;
}
p += len;
proc->in_len += len;
size -= len;
}
/* we have read 4 characters, now decode the pid */
memcpy(temp, proc->in_buff, 4);
temp[4] = 0;
if (sscanf( temp, "%04x", &proc->pid ) != 1) {
D("could not decode JDWP %p PID number: '%s'\n", proc, temp);
goto CloseProcess;
}
/* all is well, keep reading to detect connection closure */
D("Adding pid %d to jdwp process list\n", 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];
for (;;) {
int len = recv(socket, buf, sizeof(buf), 0);
if (len <= 0) {
if (len < 0 && errno == EINTR)
continue;
if (len < 0 && errno == EAGAIN)
return;
else {
D("terminating JDWP %d connection: %s\n", proc->pid,
strerror(errno));
break;
}
}
else {
D( "ignoring unexpected JDWP %d control socket activity (%d bytes)\n",
proc->pid, len );
}
}
CloseProcess:
if (proc->pid >= 0)
D( "remove pid %d to jdwp process list\n", proc->pid );
jdwp_process_free(proc);
return;
}
}
if (events & FDE_WRITE) {
D("trying to write to JDWP pid controli (count=%d first=%d) %d\n",
proc->pid, proc->out_count, proc->out_fds[0]);
if (proc->out_count > 0) {
int fd = proc->out_fds[0];
int n, ret;
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;
for (;;) {
ret = sendmsg(proc->socket, &msg, 0);
if (ret >= 0)
break;
if (errno == EINTR)
continue;
D("sending new file descriptor to JDWP %d failed: %s\n",
proc->pid, strerror(errno));
goto CloseProcess;
}
D("sent file descriptor %d to JDWP process %d\n",
fd, proc->pid);
for (n = 1; n < proc->out_count; n++)
proc->out_fds[n-1] = proc->out_fds[n];
if (--proc->out_count == 0)
fdevent_del( proc->fde, FDE_WRITE );
}
}
}
int
create_jdwp_connection_fd(int pid)
{
JdwpProcess* proc = _jdwp_list.next;
D("looking for pid %d in JDWP process list\n", pid);
for ( ; proc != &_jdwp_list; proc = proc->next ) {
if (proc->pid == pid) {
goto FoundIt;
}
}
D("search failed !!\n");
return -1;
FoundIt:
{
int fds[2];
if (proc->out_count >= MAX_OUT_FDS) {
D("%s: too many pending JDWP connection for pid %d\n",
__FUNCTION__, pid);
return -1;
}
if (adb_socketpair(fds) < 0) {
D("%s: socket pair creation failed: %s\n",
__FUNCTION__, strerror(errno));
return -1;
}
proc->out_fds[ proc->out_count ] = fds[1];
if (++proc->out_count == 1)
fdevent_add( proc->fde, FDE_WRITE );
return fds[0];
}
}
/** 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)
typedef struct {
int listen_socket;
fdevent* fde;
} JdwpControl;
static void
jdwp_control_event(int s, unsigned events, void* user);
static int
jdwp_control_init( JdwpControl* control,
const char* sockname,
int socknamelen )
{
struct 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)\n",
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_STREAM, 0 );
if (s < 0) {
D( "could not create vm debug control socket. %d: %s\n",
errno, strerror(errno));
return -1;
}
addrlen = (pathlen + sizeof(addr.sun_family));
if (bind(s, (struct sockaddr*)&addr, addrlen) < 0) {
D( "could not bind vm debug control socket: %d: %s\n",
errno, strerror(errno) );
adb_close(s);
return -1;
}
if ( listen(s, 4) < 0 ) {
D("listen failed in jdwp control socket: %d: %s\n",
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\n" );
adb_close(s);
return -1;
}
/* only wait for incoming connections */
fdevent_add(control->fde, FDE_READ);
D("jdwp control socket started (%d)\n", control->listen_socket);
return 0;
}
static void
jdwp_control_event( int s, unsigned events, void* _control )
{
JdwpControl* control = (JdwpControl*) _control;
if (events & FDE_READ) {
struct sockaddr addr;
socklen_t addrlen = sizeof(addr);
int s = -1;
JdwpProcess* proc;
do {
s = adb_socket_accept( control->listen_socket, &addr, &addrlen );
if (s < 0) {
if (errno == EINTR)
continue;
if (errno == ECONNABORTED) {
/* oops, the JDWP process died really quick */
D("oops, the JDWP process died really quick\n");
return;
}
/* the socket is probably closed ? */
D( "weird accept() failed on jdwp control socket: %s\n",
strerror(errno) );
return;
}
}
while (s < 0);
proc = jdwp_process_alloc( s );
if (proc == NULL)
return;
}
}
static JdwpControl _jdwp_control;
/** "jdwp" local service implementation
** this simply returns the list of known JDWP process pids
**/
typedef struct {
asocket socket;
int pass;
} JdwpSocket;
static void
jdwp_socket_close( asocket* s )
{
asocket* peer = s->peer;
remove_socket(s);
if (peer) {
peer->peer = NULL;
peer->close(peer);
}
free(s);
}
static int
jdwp_socket_enqueue( asocket* s, apacket* p )
{
/* you can't write to this asocket */
put_apacket(p);
s->peer->close(s->peer);
return -1;
}
static void
jdwp_socket_ready( asocket* s )
{
JdwpSocket* jdwp = (JdwpSocket*)s;
asocket* peer = jdwp->socket.peer;
/* on the first call, send the list of pids,
* on the second one, close the connection
*/
if (jdwp->pass == 0) {
apacket* p = get_apacket();
p->len = jdwp_process_list((char*)p->data, MAX_PAYLOAD);
peer->enqueue(peer, p);
jdwp->pass = 1;
}
else {
peer->close(peer);
}
}
asocket*
create_jdwp_service_socket( void )
{
JdwpSocket* s = calloc(sizeof(*s),1);
if (s == NULL)
return NULL;
install_local_socket(&s->socket);
s->socket.ready = jdwp_socket_ready;
s->socket.enqueue = jdwp_socket_enqueue;
s->socket.close = jdwp_socket_close;
s->pass = 0;
return &s->socket;
}
/** "track-jdwp" local service implementation
** this periodically sends the list of known JDWP process pids
** to the client...
**/
typedef struct JdwpTracker JdwpTracker;
struct JdwpTracker {
asocket socket;
JdwpTracker* next;
JdwpTracker* prev;
int need_update;
};
static JdwpTracker _jdwp_trackers_list;
static void
jdwp_process_list_updated(void)
{
char buffer[1024];
int len;
JdwpTracker* t = _jdwp_trackers_list.next;
len = jdwp_process_list_msg(buffer, sizeof(buffer));
for ( ; t != &_jdwp_trackers_list; t = t->next ) {
apacket* p = get_apacket();
asocket* peer = t->socket.peer;
memcpy(p->data, buffer, len);
p->len = len;
peer->enqueue( peer, p );
}
}
static void
jdwp_tracker_close( asocket* s )
{
JdwpTracker* tracker = (JdwpTracker*) s;
asocket* peer = s->peer;
if (peer) {
peer->peer = NULL;
peer->close(peer);
}
remove_socket(s);
tracker->prev->next = tracker->next;
tracker->next->prev = tracker->prev;
free(s);
}
static void
jdwp_tracker_ready( asocket* s )
{
JdwpTracker* t = (JdwpTracker*) s;
if (t->need_update) {
apacket* p = get_apacket();
t->need_update = 0;
p->len = jdwp_process_list_msg((char*)p->data, sizeof(p->data));
s->peer->enqueue(s->peer, p);
}
}
static int
jdwp_tracker_enqueue( asocket* s, apacket* p )
{
/* you can't write to this socket */
put_apacket(p);
s->peer->close(s->peer);
return -1;
}
asocket*
create_jdwp_tracker_service_socket( void )
{
JdwpTracker* t = calloc(sizeof(*t),1);
if (t == NULL)
return NULL;
t->next = &_jdwp_trackers_list;
t->prev = t->next->prev;
t->next->prev = t;
t->prev->next = t;
install_local_socket(&t->socket);
t->socket.ready = jdwp_tracker_ready;
t->socket.enqueue = jdwp_tracker_enqueue;
t->socket.close = jdwp_tracker_close;
t->need_update = 1;
return &t->socket;
}
int
init_jdwp(void)
{
_jdwp_list.next = &_jdwp_list;
_jdwp_list.prev = &_jdwp_list;
_jdwp_trackers_list.next = &_jdwp_trackers_list;
_jdwp_trackers_list.prev = &_jdwp_trackers_list;
return jdwp_control_init( &_jdwp_control,
JDWP_CONTROL_NAME,
JDWP_CONTROL_NAME_LEN );
}
#endif /* !ADB_HOST */