/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2010 Lennart Poettering Copyright 2013 Daniel Mack Copyright 2014 Kay Sievers Copyright 2014 David Herrmann systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <sys/socket.h> #include <sys/types.h> #include <string.h> #include <errno.h> #include <poll.h> #include "log.h" #include "util.h" #include "sd-daemon.h" #include "sd-bus.h" #include "bus-internal.h" #include "bus-message.h" #include "bus-util.h" #include "strv.h" #include "bus-control.h" #include "set.h" #include "bus-xml-policy.h" #include "driver.h" #include "proxy.h" #include "synthesize.h" #include "formats-util.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 = UID_INVALID; b->fake_creds.euid = p->local_creds.uid; b->fake_creds.suid = UID_INVALID; b->fake_creds.fsuid = UID_INVALID; b->fake_creds.gid = GID_INVALID; b->fake_creds.egid = p->local_creds.gid; b->fake_creds.sgid = GID_INVALID; b->fake_creds.fsgid = GID_INVALID; 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("/usr/share/dbus-1/system.conf", "/etc/dbus-1/system.conf", "/usr/share/dbus-1/system.d/", "/etc/dbus-1/system.d/", "/etc/dbus-1/system-local.conf", NULL); else if (streq(scope, "user")) strv = strv_new("/usr/share/dbus-1/session.conf", "/etc/dbus-1/session.conf", "/usr/share/dbus-1/session.d/", "/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; /* * dbus-1 distinguishes expected and non-expected replies by tracking * method-calls and timeouts. By default, DENY rules are *NEVER* applied * on expected replies, unless explicitly specified. But we dont track * method-calls, thus, we cannot know whether a reply is expected. * Fortunately, the kdbus forbids non-expected replies, so we can safely * ignore any policy on those and let the kernel deal with it. * * TODO: To be correct, we should only ignore policy-tags that are * applied on non-expected replies. However, so far we don't parse those * tags so we let everything pass. I haven't seen a DENY policy tag on * expected-replies, ever, so don't bother.. */ 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 * client, then the message creds will be * missing, simply because on legacy clients * per-message creds were unknown. In this * case, query the creds of the peer * instead. */ 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 * name's policy we used, and to which unique ID it * mapped when we made the decision. Then, let's pass * this to the kernel when sending the message, so that * it refuses the operation should the name and unique * ID not map to each other anymore. */ 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, * we have no idea who the recipient is. * Therefore, we cannot apply any dbus-1 * receiver policies that match on receiver * credentials. We know sd-bus always sets * KDBUS_MSG_SIGNAL, so the kernel applies * receiver policies to the message. Therefore, * skip policy checks in this case. */ 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: * the callback reply and the NameAcquired for the unique * name, since hello is otherwise obsolete on kdbus. */ 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 * so that they originate from the bus driver. This is a * speciality originating from dbus1, where the bus driver did * not have a unique id, but only the well-known name. */ 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 == -ECONNRESET || r == -ENOTCONN) return r; 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 == -ECONNRESET || r == -ENOTCONN) return r; 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 * rejected with EPERM by the kernel, we ignore the * error. This catches cases where the original * method-call didn't had EXPECT_REPLY set, but the * proxy-peer still sends a reply. This is allowed in * dbus1, but not in kdbus. We don't want to track * reply-windows in the proxy, so we simply ignore * EPERM for all replies. The only downside is, that * callers are no longer notified if their replies are * dropped. However, this is equivalent to the * caller's timeout to expire, so this should be * acceptable. Nobody sane sends replies without a * matching method-call, so nobody should care. */ 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"); if (r == -ENOBUFS) { /* if local dbus1 peer does not dispatch its queue, warn only once */ if (!p->queue_overflow) log_error("Dropped messages due to queue overflow of local peer (pid: "PID_FMT" uid: "UID_FMT")", p->local_creds.pid, p->local_creds.uid); p->queue_overflow = true; } else log_error_errno(r, "Failed to forward message we got from destination: uid=" UID_FMT " gid=" GID_FMT" message=%s destination=%s path=%s interface=%s member=%s: %m", p->local_creds.uid, p->local_creds.gid, bus_message_type_to_string(m->header->type), strna(m->destination), strna(m->path), strna(m->interface), strna(m->member)); return 1; } p->queue_overflow = false; 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 == -ECONNRESET || r == -ENOTCONN) return r; 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 == -ECONNRESET || r == -ENOTCONN) return r; 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 == -ECONNRESET || r == -ENOTCONN) return r; if (r < 0) return log_error_errno(r, "Failed to process policy: %m"); 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 forward message we got from local: uid=" UID_FMT " gid=" GID_FMT" message=%s destination=%s path=%s interface=%s member=%s: %m", p->local_creds.uid, p->local_creds.gid, bus_message_type_to_string(m->header->type), strna(m->destination), strna(m->path), strna(m->interface), strna(m->member)); 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 == -ECONNRESET || r == -ENOTCONN) return 0; if (r < 0) return r; } } return 0; }