d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <sys/socket.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <sys/un.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <sys/types.h>

63c372cb9df3bee01e3bf8cd7f96f336bddda846Lennart Poettering#include <fcntl.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <unistd.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <string.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <errno.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <poll.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <stddef.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include <getopt.h>

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "log.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "util.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "socket-util.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "sd-daemon.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "sd-bus.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "bus-internal.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "bus-message.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "bus-util.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "build.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "strv.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "def.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "capability.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "bus-control.h"

d6170d27b26eeeace966bb9720d66fcac2a6ef1bZbigniew Jędrzejewski-Szmek#include "smack-util.h"

#include "set.h"

#include "bus-xml-policy.h"

#include "driver.h"

#include "proxy.h"

#include "synthesize.h"

static int proxy_create_destination(Proxy *p, const char *destination, const char *local_sec, bool negotiate_fds) {

_cleanup_bus_close_unref_ sd_bus *b = NULL;

int r;

r = sd_bus_new(&b);

if (r < 0)

return log_error_errno(r, "Failed to allocate bus: %m");

r = sd_bus_set_description(b, "sd-proxy");

if (r < 0)

return log_error_errno(r, "Failed to set bus name: %m");

r = sd_bus_set_address(b, destination);

if (r < 0)

return log_error_errno(r, "Failed to set address to connect to: %m");

r = sd_bus_negotiate_fds(b, negotiate_fds);

if (r < 0)

return log_error_errno(r, "Failed to set FD negotiation: %m");

r = sd_bus_negotiate_creds(b, true, SD_BUS_CREDS_EUID|SD_BUS_CREDS_PID|SD_BUS_CREDS_EGID|SD_BUS_CREDS_SELINUX_CONTEXT);

if (r < 0)

return log_error_errno(r, "Failed to set credential negotiation: %m");

if (p->local_creds.pid > 0) {

b->fake_pids.pid = p->local_creds.pid;

b->fake_pids_valid = true;

b->fake_creds.uid = p->local_creds.uid;

b->fake_creds.euid = p->local_creds.uid;

b->fake_creds.suid = p->local_creds.uid;

b->fake_creds.fsuid = p->local_creds.uid;

b->fake_creds.gid = p->local_creds.gid;

b->fake_creds.egid = p->local_creds.gid;

b->fake_creds.sgid = p->local_creds.gid;

b->fake_creds.fsgid = p->local_creds.gid;

b->fake_creds_valid = true;

}

if (local_sec) {

b->fake_label = strdup(local_sec);

if (!b->fake_label)

return log_oom();

}

b->manual_peer_interface = true;

r = sd_bus_start(b);

if (r < 0)

return log_error_errno(r, "Failed to start bus client: %m");

p->destination_bus = b;

b = NULL;

return 0;

}

static int proxy_create_local(Proxy *p, int in_fd, int out_fd, bool negotiate_fds) {

_cleanup_bus_close_unref_ sd_bus *b = NULL;

sd_id128_t server_id;

int r;

r = sd_bus_new(&b);

if (r < 0)

return log_error_errno(r, "Failed to allocate bus: %m");

r = sd_bus_set_fd(b, in_fd, out_fd);

if (r < 0)

return log_error_errno(r, "Failed to set fds: %m");

r = sd_bus_get_bus_id(p->destination_bus, &server_id);

if (r < 0)

return log_error_errno(r, "Failed to get server ID: %m");

r = sd_bus_set_server(b, 1, server_id);

if (r < 0)

return log_error_errno(r, "Failed to set server mode: %m");

r = sd_bus_negotiate_fds(b, negotiate_fds);

if (r < 0)

return log_error_errno(r, "Failed to set FD negotiation: %m");

r = sd_bus_negotiate_creds(b, true, SD_BUS_CREDS_EUID|SD_BUS_CREDS_PID|SD_BUS_CREDS_EGID|SD_BUS_CREDS_SELINUX_CONTEXT);

if (r < 0)

return log_error_errno(r, "Failed to set credential negotiation: %m");

r = sd_bus_set_anonymous(b, true);

if (r < 0)

return log_error_errno(r, "Failed to set anonymous authentication: %m");

b->manual_peer_interface = true;

r = sd_bus_start(b);

if (r < 0)

return log_error_errno(r, "Failed to start bus client: %m");

p->local_bus = b;

b = NULL;

return 0;

}

static int proxy_prepare_matches(Proxy *p) {

_cleanup_free_ char *match = NULL;

const char *unique;

int r;

if (!p->destination_bus->is_kernel)

return 0;

r = sd_bus_get_unique_name(p->destination_bus, &unique);

if (r < 0)

return log_error_errno(r, "Failed to get unique name: %m");

match = strjoin("type='signal',"

"sender='org.freedesktop.DBus',"

"path='/org/freedesktop/DBus',"

"interface='org.freedesktop.DBus',"

"member='NameOwnerChanged',"

"arg1='",

unique,

"'",

NULL);

if (!match)

return log_oom();

r = sd_bus_add_match(p->destination_bus, NULL, match, NULL, NULL);

if (r < 0)

return log_error_errno(r, "Failed to add match for NameLost: %m");

free(match);

match = strjoin("type='signal',"

"sender='org.freedesktop.DBus',"

"path='/org/freedesktop/DBus',"

"interface='org.freedesktop.DBus',"

"member='NameOwnerChanged',"

"arg2='",

unique,

"'",

NULL);

if (!match)

return log_oom();

r = sd_bus_add_match(p->destination_bus, NULL, match, NULL, NULL);

if (r < 0)

return log_error_errno(r, "Failed to add match for NameAcquired: %m");

return 0;

}

int proxy_new(Proxy **out, int in_fd, int out_fd, const char *destination) {

_cleanup_(proxy_freep) Proxy *p = NULL;

_cleanup_free_ char *local_sec = NULL;

bool is_unix;

int r;

p = new0(Proxy, 1);

if (!p)

return log_oom();

p->local_in = in_fd;

p->local_out = out_fd;

p->owned_names = set_new(&string_hash_ops);

if (!p->owned_names)

return log_oom();

is_unix = sd_is_socket(in_fd, AF_UNIX, 0, 0) > 0 &&

sd_is_socket(out_fd, AF_UNIX, 0, 0) > 0;

if (is_unix) {

(void) getpeercred(in_fd, &p->local_creds);

(void) getpeersec(in_fd, &local_sec);

}

r = proxy_create_destination(p, destination, local_sec, is_unix);

if (r < 0)

return r;

r = proxy_create_local(p, in_fd, out_fd, is_unix);

if (r < 0)

return r;

r = proxy_prepare_matches(p);

if (r < 0)

return r;

*out = p;

p = NULL;

return 0;

}

Proxy *proxy_free(Proxy *p) {

if (!p)

return NULL;

sd_bus_close_unrefp(&p->local_bus);

sd_bus_close_unrefp(&p->destination_bus);

set_free_free(p->owned_names);

free(p);

return NULL;

}

int proxy_set_policy(Proxy *p, SharedPolicy *sp, char **configuration) {

_cleanup_strv_free_ char **strv = NULL;

Policy *policy;

int r;

assert(p);

assert(sp);

/* no need to load legacy policy if destination is not kdbus */

if (!p->destination_bus->is_kernel)

return 0;

p->policy = sp;

policy = shared_policy_acquire(sp);

if (policy) {

/* policy already pre-loaded */

shared_policy_release(sp, policy);

return 0;

}

if (!configuration) {

const char *scope;

r = sd_bus_get_scope(p->destination_bus, &scope);

if (r < 0)

return log_error_errno(r, "Couldn't determine bus scope: %m");

if (streq(scope, "system"))

strv = strv_new("/etc/dbus-1/system.conf",

"/etc/dbus-1/system.d/",

"/etc/dbus-1/system-local.conf",

NULL);

else if (streq(scope, "user"))

strv = strv_new("/etc/dbus-1/session.conf",

"/etc/dbus-1/session.d/",

"/etc/dbus-1/session-local.conf",

NULL);

else

return log_error("Unknown scope %s, don't know which policy to load. Refusing.", scope);

if (!strv)

return log_oom();

configuration = strv;

}

return shared_policy_preload(sp, configuration);

}

int proxy_hello_policy(Proxy *p, uid_t original_uid) {

Policy *policy;

int r = 0;

assert(p);

if (!p->policy)

return 0;

policy = shared_policy_acquire(p->policy);

if (p->local_creds.uid == original_uid)

log_debug("Permitting access, since bus owner matches bus client.");

else if (policy_check_hello(policy, p->local_creds.uid, p->local_creds.gid))

log_debug("Permitting access due to XML policy.");

else

r = log_error_errno(EPERM, "Policy denied connection.");

shared_policy_release(p->policy, policy);

return r;

}

static int proxy_wait(Proxy *p) {

uint64_t timeout_destination, timeout_local, t;

int events_destination, events_local, fd;

struct timespec _ts, *ts;

struct pollfd *pollfd;

int r;

assert(p);

fd = sd_bus_get_fd(p->destination_bus);

if (fd < 0)

return log_error_errno(fd, "Failed to get fd: %m");

events_destination = sd_bus_get_events(p->destination_bus);

if (events_destination < 0)

return log_error_errno(events_destination, "Failed to get events mask: %m");

r = sd_bus_get_timeout(p->destination_bus, &timeout_destination);

if (r < 0)

return log_error_errno(r, "Failed to get timeout: %m");

events_local = sd_bus_get_events(p->local_bus);

if (events_local < 0)

return log_error_errno(events_local, "Failed to get events mask: %m");

r = sd_bus_get_timeout(p->local_bus, &timeout_local);

if (r < 0)

return log_error_errno(r, "Failed to get timeout: %m");

t = timeout_destination;

if (t == (uint64_t) -1 || (timeout_local != (uint64_t) -1 && timeout_local < timeout_destination))

t = timeout_local;

if (t == (uint64_t) -1)

ts = NULL;

else {

usec_t nw;

nw = now(CLOCK_MONOTONIC);

if (t > nw)

t -= nw;

else

t = 0;

ts = timespec_store(&_ts, t);

}

pollfd = (struct pollfd[3]) {

{ .fd = fd, .events = events_destination, },

{ .fd = p->local_in, .events = events_local & POLLIN, },

{ .fd = p->local_out, .events = events_local & POLLOUT, },

};

r = ppoll(pollfd, 3, ts, NULL);

if (r < 0)

return log_error_errno(errno, "ppoll() failed: %m");

return 0;

}

static int handle_policy_error(sd_bus_message *m, int r) {

if (r == -ESRCH || r == -ENXIO)

return synthetic_reply_method_errorf(m, SD_BUS_ERROR_NAME_HAS_NO_OWNER, "Name %s is currently not owned by anyone.", m->destination);

return r;

}

static int process_policy_unlocked(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *policy, const struct ucred *our_ucred, Set *owned_names) {

int r;

assert(from);

assert(to);

assert(m);

if (!policy)

return 0;

/*

if (m->reply_cookie > 0)

return 0;

if (from->is_kernel) {

uid_t sender_uid = UID_INVALID;

gid_t sender_gid = GID_INVALID;

char **sender_names = NULL;

/* Driver messages are always OK */

if (streq_ptr(m->sender, "org.freedesktop.DBus"))

return 0;

/* The message came from the kernel, and is sent to our legacy client. */

(void) sd_bus_creds_get_well_known_names(&m->creds, &sender_names);

(void) sd_bus_creds_get_euid(&m->creds, &sender_uid);

(void) sd_bus_creds_get_egid(&m->creds, &sender_gid);

if (sender_uid == UID_INVALID || sender_gid == GID_INVALID) {

_cleanup_bus_creds_unref_ sd_bus_creds *sender_creds = NULL;

/* If the message came from another legacy

r = bus_get_name_creds_kdbus(from, m->sender, SD_BUS_CREDS_EUID|SD_BUS_CREDS_EGID, true, &sender_creds);

if (r < 0)

return handle_policy_error(m, r);

(void) sd_bus_creds_get_euid(sender_creds, &sender_uid);

(void) sd_bus_creds_get_egid(sender_creds, &sender_gid);

}

/* First check whether the sender can send the message to our name */

if (policy_check_send(policy, sender_uid, sender_gid, m->header->type, owned_names, NULL, m->path, m->interface, m->member, false, NULL) &&

policy_check_recv(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, sender_names, m->path, m->interface, m->member, false))

return 0;

/* Return an error back to the caller */

if (m->header->type == SD_BUS_MESSAGE_METHOD_CALL)

return synthetic_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML receiver policy.");

/* Return 1, indicating that the message shall not be processed any further */

return 1;

}

if (to->is_kernel) {

_cleanup_bus_creds_unref_ sd_bus_creds *destination_creds = NULL;

uid_t destination_uid = UID_INVALID;

gid_t destination_gid = GID_INVALID;

const char *destination_unique = NULL;

char **destination_names = NULL;

char *n;

/* Driver messages are always OK */

if (streq_ptr(m->destination, "org.freedesktop.DBus"))

return 0;

/* The message came from the legacy client, and is sent to kdbus. */

if (m->destination) {

r = bus_get_name_creds_kdbus(to, m->destination,

SD_BUS_CREDS_WELL_KNOWN_NAMES|SD_BUS_CREDS_UNIQUE_NAME|

SD_BUS_CREDS_EUID|SD_BUS_CREDS_EGID|SD_BUS_CREDS_PID,

true, &destination_creds);

if (r < 0)

return handle_policy_error(m, r);

r = sd_bus_creds_get_unique_name(destination_creds, &destination_unique);

if (r < 0)

return handle_policy_error(m, r);

(void) sd_bus_creds_get_well_known_names(destination_creds, &destination_names);

(void) sd_bus_creds_get_euid(destination_creds, &destination_uid);

(void) sd_bus_creds_get_egid(destination_creds, &destination_gid);

}

/* First check if we (the sender) can send to this name */

if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, destination_names, m->path, m->interface, m->member, true, &n)) {

if (n) {

/* If we made a receiver decision, then remember which

r = free_and_strdup(&m->destination_ptr, n);

if (r < 0)

return r;

r = bus_kernel_parse_unique_name(destination_unique, &m->verify_destination_id);

if (r < 0)

return r;

}

if (sd_bus_message_is_signal(m, NULL, NULL)) {

/* If we forward a signal from dbus-1 to kdbus,

return 0;

} else if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, owned_names, NULL, m->path, m->interface, m->member, true)) {

return 0;

}

}

/* Return an error back to the caller */

if (m->header->type == SD_BUS_MESSAGE_METHOD_CALL)

return synthetic_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML sender policy.");

/* Return 1, indicating that the message shall not be processed any further */

return 1;

}

return 0;

}

static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, SharedPolicy *sp, const struct ucred *our_ucred, Set *owned_names) {

Policy *policy;

int r;

assert(sp);

policy = shared_policy_acquire(sp);

r = process_policy_unlocked(from, to, m, policy, our_ucred, owned_names);

shared_policy_release(sp, policy);

return r;

}

static int process_hello(Proxy *p, sd_bus_message *m) {

_cleanup_bus_message_unref_ sd_bus_message *n = NULL;

bool is_hello;

int r;

assert(p);

assert(m);

/* As reaction to hello we need to respond with two messages:

is_hello =

sd_bus_message_is_method_call(m, "org.freedesktop.DBus", "Hello") &&

streq_ptr(m->destination, "org.freedesktop.DBus");

if (!is_hello) {

if (p->got_hello)

return 0;

return log_error_errno(EIO, "First packet isn't hello (it's %s.%s), aborting.", m->interface, m->member);

}

if (p->got_hello)

return log_error_errno(EIO, "Got duplicate hello, aborting.");

p->got_hello = true;

if (!p->destination_bus->is_kernel)

return 0;

r = sd_bus_message_new_method_return(m, &n);

if (r < 0)

return log_error_errno(r, "Failed to generate HELLO reply: %m");

r = sd_bus_message_append(n, "s", p->destination_bus->unique_name);

if (r < 0)

return log_error_errno(r, "Failed to append unique name to HELLO reply: %m");

r = bus_message_append_sender(n, "org.freedesktop.DBus");

if (r < 0)

return log_error_errno(r, "Failed to append sender to HELLO reply: %m");

r = bus_seal_synthetic_message(p->local_bus, n);

if (r < 0)

return log_error_errno(r, "Failed to seal HELLO reply: %m");

r = sd_bus_send(p->local_bus, n, NULL);

if (r < 0)

return log_error_errno(r, "Failed to send HELLO reply: %m");

n = sd_bus_message_unref(n);

r = sd_bus_message_new_signal(

p->local_bus,

&n,

"/org/freedesktop/DBus",

"org.freedesktop.DBus",

"NameAcquired");

if (r < 0)

return log_error_errno(r, "Failed to allocate initial NameAcquired message: %m");

r = sd_bus_message_append(n, "s", p->destination_bus->unique_name);

if (r < 0)

return log_error_errno(r, "Failed to append unique name to NameAcquired message: %m");

r = bus_message_append_sender(n, "org.freedesktop.DBus");

if (r < 0)

return log_error_errno(r, "Failed to append sender to NameAcquired message: %m");

r = bus_seal_synthetic_message(p->local_bus, n);

if (r < 0)

return log_error_errno(r, "Failed to seal NameAcquired message: %m");

r = sd_bus_send(p->local_bus, n, NULL);

if (r < 0)

return log_error_errno(r, "Failed to send NameAcquired message: %m");

return 1;

}

static int patch_sender(sd_bus *a, sd_bus_message *m) {

char **well_known = NULL;

sd_bus_creds *c;

int r;

assert(a);

assert(m);

if (!a->is_kernel)

return 0;

/* We will change the sender of messages from the bus driver

c = sd_bus_message_get_creds(m);

if (!c)

return 0;

r = sd_bus_creds_get_well_known_names(c, &well_known);

if (r < 0)

return r;

if (strv_contains(well_known, "org.freedesktop.DBus"))

m->sender = "org.freedesktop.DBus";

return 0;

}

static int proxy_process_destination_to_local(Proxy *p) {

_cleanup_bus_message_unref_ sd_bus_message *m = NULL;

int r;

assert(p);

r = sd_bus_process(p->destination_bus, &m);

if (r == -ECONNRESET || r == -ENOTCONN) /* Treat 'connection reset by peer' as clean exit condition */

return r;

if (r < 0) {

log_error_errno(r, "Failed to process destination bus: %m");

return r;

}

if (r == 0)

return 0;

if (!m)

return 1;

/* We officially got EOF, let's quit */

if (sd_bus_message_is_signal(m, "org.freedesktop.DBus.Local", "Disconnected"))

return -ECONNRESET;

r = synthesize_name_acquired(p->destination_bus, p->local_bus, m);

if (r < 0)

return log_error_errno(r, "Failed to synthesize message: %m");

patch_sender(p->destination_bus, m);

if (p->policy) {

r = process_policy(p->destination_bus, p->local_bus, m, p->policy, &p->local_creds, p->owned_names);

if (r < 0)

return log_error_errno(r, "Failed to process policy: %m");

if (r > 0)

return 1;

}

r = sd_bus_send(p->local_bus, m, NULL);

if (r < 0) {

if (r == -ECONNRESET || r == -ENOTCONN)

return r;

/* If the peer tries to send a reply and it is

if (r == -EPERM && m->reply_cookie > 0)

return 1;

/* Return the error to the client, if we can */

synthetic_reply_method_errnof(m, r, "Failed to forward message we got from destination: %m");

log_error_errno(r, "Failed to send message to client, ignoring: %m");

return 1;

}

return 1;

}

static int proxy_process_local_to_destination(Proxy *p) {

_cleanup_bus_message_unref_ sd_bus_message *m = NULL;

int r;

assert(p);

r = sd_bus_process(p->local_bus, &m);

if (r == -ECONNRESET || r == -ENOTCONN) /* Treat 'connection reset by peer' as clean exit condition */

return r;

if (r < 0) {

log_error_errno(r, "Failed to process local bus: %m");

return r;

}

if (r == 0)

return 0;

if (!m)

return 1;

/* We officially got EOF, let's quit */

if (sd_bus_message_is_signal(m, "org.freedesktop.DBus.Local", "Disconnected"))

return -ECONNRESET;

r = process_hello(p, m);

if (r < 0)

return log_error_errno(r, "Failed to process HELLO: %m");

if (r > 0)

return 1;

r = bus_proxy_process_driver(p->destination_bus, p->local_bus, m, p->policy, &p->local_creds, p->owned_names);

if (r < 0)

return log_error_errno(r, "Failed to process driver calls: %m");

if (r > 0)

return 1;

for (;;) {

if (p->policy) {

r = process_policy(p->local_bus, p->destination_bus, m, p->policy, &p->local_creds, p->owned_names);

if (r < 0)

return log_error_errno(r, "Failed to process policy: %m");

else if (r > 0)

return 1;

}

r = sd_bus_send(p->destination_bus, m, NULL);

if (r < 0) {

if (r == -ECONNRESET || r == -ENOTCONN)

return r;

/* The name database changed since the policy check, hence let's check again */

if (r == -EREMCHG)

continue;

/* see above why EPERM is ignored for replies */

if (r == -EPERM && m->reply_cookie > 0)

return 1;

synthetic_reply_method_errnof(m, r, "Failed to forward message we got from local: %m");

log_error_errno(r, "Failed to send message to bus: %m");

return 1;

}

break;

}

return 1;

}

int proxy_run(Proxy *p) {

int r;

assert(p);

for (;;) {

bool busy = false;

if (p->got_hello) {

/* Read messages from bus, to pass them on to our client */

r = proxy_process_destination_to_local(p);

if (r == -ECONNRESET || r == -ENOTCONN)

return 0;

if (r < 0)

return r;

if (r > 0)

busy = true;

}

/* Read messages from our client, to pass them on to the bus */

r = proxy_process_local_to_destination(p);

if (r == -ECONNRESET || r == -ENOTCONN)

return 0;

if (r < 0)

return r;

if (r > 0)

busy = true;

if (!busy) {

r = proxy_wait(p);

if (r < 0)

return r;

}

}

return 0;

}