/*
* vim:ts=4:sw=4:expandtab
*
* i3 - an improved dynamic tiling window manager
* © 2009 Michael Stapelberg and contributors (see also: LICENSE)
*
* inject_randr1.5.c: An X11 proxy which interprets RandR 1.5 GetMonitors
* requests and overwrites their reply with a custom reply.
*
* This tool can be refactored as necessary in order to perform the same
* purpose for other request types. The RandR 1.5 specific portions of the code
* have been marked as such to make such a refactoring easier.
*
*/
#include "all.h"
#include <ev.h>
#include <fcntl.h>
#include <getopt.h>
#include <libgen.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <unistd.h>
static void uds_connection_cb(EV_P_ ev_io *w, int revents);
static void read_client_setup_request_cb(EV_P_ ev_io *w, int revents);
static void read_server_setup_reply_cb(EV_P_ ev_io *w, int revents);
static void read_client_x11_packet_cb(EV_P_ ev_io *w, int revents);
static void read_server_x11_packet_cb(EV_P_ ev_io *w, int revents);
static char *sun_path = NULL;
static void cleanup_socket(void) {
if (sun_path != NULL) {
unlink(sun_path);
free(sun_path);
sun_path = NULL;
}
}
struct injected_reply {
void *buf;
off_t len;
};
/* BEGIN RandR 1.5 specific */
static struct injected_reply getmonitors_reply = {NULL, 0};
static struct injected_reply getoutputinfo_reply = {NULL, 0};
/* END RandR 1.5 specific */
#define XCB_PAD(i) (-(i)&3)
struct connstate {
/* clientw is a libev watcher for the connection which we accept()ed. */
ev_io *clientw;
/* serverw is a libev watcher for the connection to X11 which we initiated
* on behalf of the client. */
ev_io *serverw;
/* sequence is the client-side sequence number counter. In X11’s wire
* encoding, sequence counters are not included in requests, only in
* replies. */
int sequence;
/* BEGIN RandR 1.5 specific */
/* sequence number of the most recent GetExtension request for RANDR */
int getext_randr;
/* sequence number of the most recent RRGetMonitors request */
int getmonitors;
/* sequence number of the most recent RRGetOutputInfo request */
int getoutputinfo;
int randr_major_opcode;
/* END RandR 1.5 specific */
};
/*
* Returns 0 on EOF
* Returns -1 on error (with errno from read() untouched)
*
*/
static size_t readall_into(void *buffer, const size_t len, int fd) {
size_t read_bytes = 0;
while (read_bytes < len) {
ssize_t n = read(fd, buffer + read_bytes, len - read_bytes);
if (n <= 0) {
return n;
}
read_bytes += (size_t)n;
}
return read_bytes;
}
/*
* Exits the program with an error if the read failed.
*
*/
static void must_read(int n) {
if (n == -1) {
err(EXIT_FAILURE, "read()");
}
if (n == 0) {
errx(EXIT_FAILURE, "EOF");
}
}
/*
* Exits the program with an error if the write failed.
*
*/
static void must_write(int n) {
if (n == -1) {
err(EXIT_FAILURE, "write()");
}
}
static void uds_connection_cb(EV_P_ ev_io *w, int revents) {
struct sockaddr_un addr;
socklen_t addrlen = sizeof(addr);
const int clientfd = accept(w->fd, (struct sockaddr *)&addr, &addrlen);
if (clientfd == -1) {
if (errno == EINTR) {
return;
}
err(EXIT_FAILURE, "accept()");
}
struct connstate *connstate = scalloc(1, sizeof(struct connstate));
ev_io *clientw = scalloc(1, sizeof(ev_io));
connstate->clientw = clientw;
clientw->data = connstate;
ev_io_init(clientw, read_client_setup_request_cb, clientfd, EV_READ);
ev_io_start(EV_A_ clientw);
}
// https://www.x.org/releases/current/doc/xproto/x11protocol.html#Encoding::Connection_Setup
static void read_client_setup_request_cb(EV_P_ ev_io *w, int revents) {
ev_io_stop(EV_A_ w);
struct connstate *connstate = (struct connstate *)w->data;
/* Read X11 setup request in its entirety. */
xcb_setup_request_t setup_request;
must_read(readall_into(&setup_request, sizeof(setup_request), w->fd));
/* Establish a connection to X11. */
int fd = socket(AF_LOCAL, SOCK_STREAM, 0);
if (fd == -1) {
err(EXIT_FAILURE, "socket()");
}
char *host;
int displayp;
if (xcb_parse_display(getenv("DISPLAY"), &host, &displayp, NULL) == 0) {
errx(EXIT_FAILURE, "Could not parse DISPLAY=%s", getenv("DISPLAY"));
}
free(host);
struct sockaddr_un addr;
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_LOCAL;
snprintf(addr.sun_path, sizeof(addr.sun_path), "/tmp/.X11-unix/X%d", displayp);
if (connect(fd, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un)) == -1) {
err(EXIT_FAILURE, "connect(%s)", addr.sun_path);
}
/* Relay setup request. */
must_write(writeall(fd, &setup_request, sizeof(setup_request)));
if (setup_request.authorization_protocol_name_len > 0 ||
setup_request.authorization_protocol_data_len > 0) {
const size_t authlen = setup_request.authorization_protocol_name_len +
XCB_PAD(setup_request.authorization_protocol_name_len) +
setup_request.authorization_protocol_data_len +
XCB_PAD(setup_request.authorization_protocol_data_len);
void *buf = smalloc(authlen);
must_read(readall_into(buf, authlen, w->fd));
must_write(writeall(fd, buf, authlen));
free(buf);
}
/* Wait for a response from the X11 server. */
ev_io *serverw = scalloc(1, sizeof(ev_io));
connstate->serverw = serverw;
serverw->data = connstate;
ev_io_init(serverw, read_server_setup_reply_cb, fd, EV_READ);
ev_io_start(EV_A_ serverw);
}
static void read_server_setup_reply_cb(EV_P_ ev_io *w, int revents) {
struct connstate *connstate = (struct connstate *)w->data;
xcb_setup_failed_t setup_failed;
must_read(readall_into(&setup_failed, sizeof(setup_failed), w->fd));
switch (setup_failed.status) {
case 0:
errx(EXIT_FAILURE, "error authenticating at the X11 server");
case 2:
errx(EXIT_FAILURE, "two-factor auth not implemented");
case 1:
must_write(writeall(connstate->clientw->fd, &setup_failed, sizeof(xcb_setup_failed_t)));
const size_t len = (setup_failed.length * 4);
void *buf = smalloc(len);
must_read(readall_into(buf, len, w->fd));
must_write(writeall(connstate->clientw->fd, buf, len));
free(buf);
ev_set_cb(connstate->clientw, read_client_x11_packet_cb);
ev_set_cb(connstate->serverw, read_server_x11_packet_cb);
ev_io_start(EV_A_ connstate->clientw);
break;
default:
errx(EXIT_FAILURE, "X11 protocol error: expected setup_failed.status in [0..2], got %d", setup_failed.status);
}
}
// https://www.x.org/releases/current/doc/xproto/x11protocol.html#request_format
typedef struct {
uint8_t opcode;
uint8_t pad0;
uint16_t length;
} generic_x11_request_t;
// https://www.x.org/releases/current/doc/xproto/x11protocol.html#reply_format
typedef struct {
uint8_t code; /* if 1, this is a reply. if 0, this is an error. else, an event */
uint8_t pad0;
uint16_t sequence;
uint32_t length;
} generic_x11_reply_t;
static void read_client_x11_packet_cb(EV_P_ ev_io *w, int revents) {
struct connstate *connstate = (struct connstate *)w->data;
void *request = smalloc(sizeof(generic_x11_request_t));
must_read(readall_into(request, sizeof(generic_x11_request_t), connstate->clientw->fd));
const size_t len = (((generic_x11_request_t *)request)->length * 4);
if (len > sizeof(generic_x11_request_t)) {
request = srealloc(request, len);
must_read(readall_into(request + sizeof(generic_x11_request_t),
len - sizeof(generic_x11_request_t),
connstate->clientw->fd));
}
// XXX: sequence counter wrapping is not implemented, but should not be
// necessary given that this tool is scoped for test cases.
connstate->sequence++;
/* BEGIN RandR 1.5 specific */
const uint8_t opcode = ((generic_x11_request_t *)request)->opcode;
if (opcode == XCB_QUERY_EXTENSION) {
xcb_query_extension_request_t *req = request;
const char *name = request + sizeof(xcb_query_extension_request_t);
if (req->name_len == strlen("RANDR") &&
strncmp(name, "RANDR", strlen("RANDR")) == 0) {
connstate->getext_randr = connstate->sequence;
}
} else if (opcode == connstate->randr_major_opcode) {
const uint8_t randr_opcode = ((generic_x11_request_t *)request)->pad0;
if (randr_opcode == XCB_RANDR_GET_MONITORS) {
connstate->getmonitors = connstate->sequence;
} else if (randr_opcode == XCB_RANDR_GET_OUTPUT_INFO) {
connstate->getoutputinfo = connstate->sequence;
}
}
/* END RandR 1.5 specific */
must_write(writeall(connstate->serverw->fd, request, len));
free(request);
}
static bool handle_sequence(struct connstate *connstate, uint16_t sequence) {
/* BEGIN RandR 1.5 specific */
if (sequence == connstate->getmonitors) {
printf("RRGetMonitors reply!\n");
if (getmonitors_reply.buf != NULL) {
printf("injecting reply\n");
((generic_x11_reply_t *)getmonitors_reply.buf)->sequence = sequence;
must_write(writeall(connstate->clientw->fd, getmonitors_reply.buf, getmonitors_reply.len));
return true;
}
}
if (sequence == connstate->getoutputinfo) {
printf("RRGetOutputInfo reply!\n");
if (getoutputinfo_reply.buf != NULL) {
printf("injecting reply\n");
((generic_x11_reply_t *)getoutputinfo_reply.buf)->sequence = sequence;
must_write(writeall(connstate->clientw->fd, getoutputinfo_reply.buf, getoutputinfo_reply.len));
return true;
}
}
/* END RandR 1.5 specific */
return false;
}
static void read_server_x11_packet_cb(EV_P_ ev_io *w, int revents) {
struct connstate *connstate = (struct connstate *)w->data;
// all packets from the server are at least 32 bytes in length
size_t len = 32;
void *packet = smalloc(len);
must_read(readall_into(packet, len, connstate->serverw->fd));
switch (((generic_x11_reply_t *)packet)->code) {
case 0: { // error
const uint16_t sequence = ((xcb_request_error_t *)packet)->sequence;
if (handle_sequence(connstate, sequence)) {
free(packet);
return;
}
break;
}
case 1: // reply
len += ((generic_x11_reply_t *)packet)->length * 4;
if (len > 32) {
packet = srealloc(packet, len);
must_read(readall_into(packet + 32, len - 32, connstate->serverw->fd));
}
/* BEGIN RandR 1.5 specific */
const uint16_t sequence = ((generic_x11_reply_t *)packet)->sequence;
if (sequence == connstate->getext_randr) {
xcb_query_extension_reply_t *reply = packet;
connstate->randr_major_opcode = reply->major_opcode;
}
/* END RandR 1.5 specific */
if (handle_sequence(connstate, sequence)) {
free(packet);
return;
}
break;
default: // event
break;
}
must_write(writeall(connstate->clientw->fd, packet, len));
free(packet);
}
static void child_cb(EV_P_ ev_child *w, int revents) {
ev_child_stop(EV_A_ w);
if (WIFEXITED(w->rstatus)) {
exit(WEXITSTATUS(w->rstatus));
} else {
exit(WTERMSIG(w->rstatus) + 128);
}
}
static void must_read_reply(const char *filename, struct injected_reply *reply) {
FILE *f;
if ((f = fopen(filename, "r")) == NULL) {
err(EXIT_FAILURE, "fopen(%s)", filename);
}
struct stat stbuf;
if (fstat(fileno(f), &stbuf) != 0) {
err(EXIT_FAILURE, "fstat(%s)", filename);
}
reply->len = stbuf.st_size;
reply->buf = smalloc(stbuf.st_size);
int n = fread(reply->buf, 1, stbuf.st_size, f);
if (n != stbuf.st_size) {
err(EXIT_FAILURE, "fread(%s)", filename);
}
fclose(f);
}
int main(int argc, char *argv[]) {
static struct option long_options[] = {
{"getmonitors_reply", required_argument, 0, 0},
{"getoutputinfo_reply", required_argument, 0, 0},
{0, 0, 0, 0},
};
char *options_string = "";
int opt;
int option_index = 0;
while ((opt = getopt_long(argc, argv, options_string, long_options, &option_index)) != -1) {
switch (opt) {
case 0: {
const char *option_name = long_options[option_index].name;
if (strcmp(option_name, "getmonitors_reply") == 0) {
must_read_reply(optarg, &getmonitors_reply);
} else if (strcmp(option_name, "getoutputinfo_reply") == 0) {
must_read_reply(optarg, &getoutputinfo_reply);
}
break;
}
default:
exit(EXIT_FAILURE);
}
}
if (optind >= argc) {
errx(EXIT_FAILURE, "syntax: %s [options] <command>", argv[0]);
}
int fd = socket(AF_LOCAL, SOCK_STREAM, 0);
if (fd == -1) {
err(EXIT_FAILURE, "socket(AF_UNIX)");
}
if (fcntl(fd, F_SETFD, FD_CLOEXEC)) {
warn("Could not set FD_CLOEXEC");
}
struct sockaddr_un addr;
memset(&addr, 0, sizeof(struct sockaddr_un));
addr.sun_family = AF_UNIX;
int i;
bool bound = false;
for (i = 0; i < 100; i++) {
/* XXX: The path to X11 sockets differs on some platforms (e.g. Trusted
* Solaris, HPUX), but since libxcb doesn’t provide a function to
* generate the path, we’ll just have to hard-code it for now. */
snprintf(addr.sun_path, sizeof(addr.sun_path), "/tmp/.X11-unix/X%d", i);
if (bind(fd, (struct sockaddr *)&addr, sizeof(struct sockaddr_un)) == -1) {
warn("bind(%s)", addr.sun_path);
} else {
bound = true;
/* Let the user know bind() was successful, so that they know the
* error messages can be disregarded. */
fprintf(stderr, "Successfully bound to %s\n", addr.sun_path);
sun_path = sstrdup(addr.sun_path);
break;
}
}
if (!bound) {
err(EXIT_FAILURE, "bind()");
}
atexit(cleanup_socket);
/* This program will be started for each testcase which requires it, so we
* expect precisely one connection. */
if (listen(fd, 1) == -1) {
err(EXIT_FAILURE, "listen()");
}
pid_t child = fork();
if (child == -1) {
err(EXIT_FAILURE, "fork()");
}
if (child == 0) {
char *display;
sasprintf(&display, ":%d", i);
setenv("DISPLAY", display, 1);
free(display);
char **child_args = argv + optind;
execvp(child_args[0], child_args);
err(EXIT_FAILURE, "exec()");
}
struct ev_loop *loop = ev_default_loop(0);
ev_child cw;
ev_child_init(&cw, child_cb, child, 0);
ev_child_start(loop, &cw);
ev_io watcher;
ev_io_init(&watcher, uds_connection_cb, fd, EV_READ);
ev_io_start(loop, &watcher);
ev_run(loop, 0);
}