stuff

1 files changed, 1064 insertions, 0 deletions

diff --git a/src/libsystemd/libsystemd-internal/sd-bus/bus-socket.c b/src/libsystemd/libsystemd-internal/sd-bus/bus-socket.c
new file mode 100644
index 0000000000..a0008190c5
--- /dev/null
+++ b/src/libsystemd/libsystemd-internal/sd-bus/bus-socket.c
@@ -0,0 +1,1064 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Lennart Poettering
+
+  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 <endian.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <systemd/sd-bus.h>
+#include <systemd/sd-daemon.h>
+
+#include "alloc-util.h"
+#include "bus-internal.h"
+#include "bus-message.h"
+#include "bus-socket.h"
+#include "fd-util.h"
+#include "formats-util.h"
+#include "hexdecoct.h"
+#include "macro.h"
+#include "missing.h"
+#include "selinux-util.h"
+#include "signal-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "user-util.h"
+#include "utf8.h"
+#include "util.h"
+
+#define SNDBUF_SIZE (8*1024*1024)
+
+static void iovec_advance(struct iovec iov[], unsigned *idx, size_t size) {
+
+        while (size > 0) {
+                struct iovec *i = iov + *idx;
+
+                if (i->iov_len > size) {
+                        i->iov_base = (uint8_t*) i->iov_base + size;
+                        i->iov_len -= size;
+                        return;
+                }
+
+                size -= i->iov_len;
+
+                i->iov_base = NULL;
+                i->iov_len = 0;
+
+                (*idx) ++;
+        }
+}
+
+static int append_iovec(sd_bus_message *m, const void *p, size_t sz) {
+        assert(m);
+        assert(p);
+        assert(sz > 0);
+
+        m->iovec[m->n_iovec].iov_base = (void*) p;
+        m->iovec[m->n_iovec].iov_len = sz;
+        m->n_iovec++;
+
+        return 0;
+}
+
+static int bus_message_setup_iovec(sd_bus_message *m) {
+        struct bus_body_part *part;
+        unsigned n, i;
+        int r;
+
+        assert(m);
+        assert(m->sealed);
+
+        if (m->n_iovec > 0)
+                return 0;
+
+        assert(!m->iovec);
+
+        n = 1 + m->n_body_parts;
+        if (n < ELEMENTSOF(m->iovec_fixed))
+                m->iovec = m->iovec_fixed;
+        else {
+                m->iovec = new(struct iovec, n);
+                if (!m->iovec) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+        }
+
+        r = append_iovec(m, m->header, BUS_MESSAGE_BODY_BEGIN(m));
+        if (r < 0)
+                goto fail;
+
+        MESSAGE_FOREACH_PART(part, i, m)  {
+                r = bus_body_part_map(part);
+                if (r < 0)
+                        goto fail;
+
+                r = append_iovec(m, part->data, part->size);
+                if (r < 0)
+                        goto fail;
+        }
+
+        assert(n == m->n_iovec);
+
+        return 0;
+
+fail:
+        m->poisoned = true;
+        return r;
+}
+
+bool bus_socket_auth_needs_write(sd_bus *b) {
+
+        unsigned i;
+
+        if (b->auth_index >= ELEMENTSOF(b->auth_iovec))
+                return false;
+
+        for (i = b->auth_index; i < ELEMENTSOF(b->auth_iovec); i++) {
+                struct iovec *j = b->auth_iovec + i;
+
+                if (j->iov_len > 0)
+                        return true;
+        }
+
+        return false;
+}
+
+static int bus_socket_write_auth(sd_bus *b) {
+        ssize_t k;
+
+        assert(b);
+        assert(b->state == BUS_AUTHENTICATING);
+
+        if (!bus_socket_auth_needs_write(b))
+                return 0;
+
+        if (b->prefer_writev)
+                k = writev(b->output_fd, b->auth_iovec + b->auth_index, ELEMENTSOF(b->auth_iovec) - b->auth_index);
+        else {
+                struct msghdr mh;
+                zero(mh);
+
+                mh.msg_iov = b->auth_iovec + b->auth_index;
+                mh.msg_iovlen = ELEMENTSOF(b->auth_iovec) - b->auth_index;
+
+                k = sendmsg(b->output_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
+                if (k < 0 && errno == ENOTSOCK) {
+                        b->prefer_writev = true;
+                        k = writev(b->output_fd, b->auth_iovec + b->auth_index, ELEMENTSOF(b->auth_iovec) - b->auth_index);
+                }
+        }
+
+        if (k < 0)
+                return errno == EAGAIN ? 0 : -errno;
+
+        iovec_advance(b->auth_iovec, &b->auth_index, (size_t) k);
+        return 1;
+}
+
+static int bus_socket_auth_verify_client(sd_bus *b) {
+        char *e, *f, *start;
+        sd_id128_t peer;
+        unsigned i;
+        int r;
+
+        assert(b);
+
+        /* We expect two response lines: "OK" and possibly
+         * "AGREE_UNIX_FD" */
+
+        e = memmem_safe(b->rbuffer, b->rbuffer_size, "\r\n", 2);
+        if (!e)
+                return 0;
+
+        if (b->hello_flags & KDBUS_HELLO_ACCEPT_FD) {
+                f = memmem(e + 2, b->rbuffer_size - (e - (char*) b->rbuffer) - 2, "\r\n", 2);
+                if (!f)
+                        return 0;
+
+                start = f + 2;
+        } else {
+                f = NULL;
+                start = e + 2;
+        }
+
+        /* Nice! We got all the lines we need. First check the OK
+         * line */
+
+        if (e - (char*) b->rbuffer != 3 + 32)
+                return -EPERM;
+
+        if (memcmp(b->rbuffer, "OK ", 3))
+                return -EPERM;
+
+        b->auth = b->anonymous_auth ? BUS_AUTH_ANONYMOUS : BUS_AUTH_EXTERNAL;
+
+        for (i = 0; i < 32; i += 2) {
+                int x, y;
+
+                x = unhexchar(((char*) b->rbuffer)[3 + i]);
+                y = unhexchar(((char*) b->rbuffer)[3 + i + 1]);
+
+                if (x < 0 || y < 0)
+                        return -EINVAL;
+
+                peer.bytes[i/2] = ((uint8_t) x << 4 | (uint8_t) y);
+        }
+
+        if (!sd_id128_equal(b->server_id, SD_ID128_NULL) &&
+            !sd_id128_equal(b->server_id, peer))
+                return -EPERM;
+
+        b->server_id = peer;
+
+        /* And possibly check the second line, too */
+
+        if (f)
+                b->can_fds =
+                        (f - e == strlen("\r\nAGREE_UNIX_FD")) &&
+                        memcmp(e + 2, "AGREE_UNIX_FD", strlen("AGREE_UNIX_FD")) == 0;
+
+        b->rbuffer_size -= (start - (char*) b->rbuffer);
+        memmove(b->rbuffer, start, b->rbuffer_size);
+
+        r = bus_start_running(b);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static bool line_equals(const char *s, size_t m, const char *line) {
+        size_t l;
+
+        l = strlen(line);
+        if (l != m)
+                return false;
+
+        return memcmp(s, line, l) == 0;
+}
+
+static bool line_begins(const char *s, size_t m, const char *word) {
+        size_t l;
+
+        l = strlen(word);
+        if (m < l)
+                return false;
+
+        if (memcmp(s, word, l) != 0)
+                return false;
+
+        return m == l || (m > l && s[l] == ' ');
+}
+
+static int verify_anonymous_token(sd_bus *b, const char *p, size_t l) {
+        _cleanup_free_ char *token = NULL;
+        size_t len;
+        int r;
+
+        if (!b->anonymous_auth)
+                return 0;
+
+        if (l <= 0)
+                return 1;
+
+        assert(p[0] == ' ');
+        p++; l--;
+
+        if (l % 2 != 0)
+                return 0;
+
+        r = unhexmem(p, l, (void **) &token, &len);
+        if (r < 0)
+                return 0;
+
+        if (memchr(token, 0, len))
+                return 0;
+
+        return !!utf8_is_valid(token);
+}
+
+static int verify_external_token(sd_bus *b, const char *p, size_t l) {
+        _cleanup_free_ char *token = NULL;
+        size_t len;
+        uid_t u;
+        int r;
+
+        /* We don't do any real authentication here. Instead, we if
+         * the owner of this bus wanted authentication he should have
+         * checked SO_PEERCRED before even creating the bus object. */
+
+        if (!b->anonymous_auth && !b->ucred_valid)
+                return 0;
+
+        if (l <= 0)
+                return 1;
+
+        assert(p[0] == ' ');
+        p++; l--;
+
+        if (l % 2 != 0)
+                return 0;
+
+        r = unhexmem(p, l, (void**) &token, &len);
+        if (r < 0)
+                return 0;
+
+        if (memchr(token, 0, len))
+                return 0;
+
+        r = parse_uid(token, &u);
+        if (r < 0)
+                return 0;
+
+        /* We ignore the passed value if anonymous authentication is
+         * on anyway. */
+        if (!b->anonymous_auth && u != b->ucred.uid)
+                return 0;
+
+        return 1;
+}
+
+static int bus_socket_auth_write(sd_bus *b, const char *t) {
+        char *p;
+        size_t l;
+
+        assert(b);
+        assert(t);
+
+        /* We only make use of the first iovec */
+        assert(b->auth_index == 0 || b->auth_index == 1);
+
+        l = strlen(t);
+        p = malloc(b->auth_iovec[0].iov_len + l);
+        if (!p)
+                return -ENOMEM;
+
+        memcpy(p, b->auth_iovec[0].iov_base, b->auth_iovec[0].iov_len);
+        memcpy(p + b->auth_iovec[0].iov_len, t, l);
+
+        b->auth_iovec[0].iov_base = p;
+        b->auth_iovec[0].iov_len += l;
+
+        free(b->auth_buffer);
+        b->auth_buffer = p;
+        b->auth_index = 0;
+        return 0;
+}
+
+static int bus_socket_auth_write_ok(sd_bus *b) {
+        char t[3 + 32 + 2 + 1];
+
+        assert(b);
+
+        xsprintf(t, "OK " SD_ID128_FORMAT_STR "\r\n", SD_ID128_FORMAT_VAL(b->server_id));
+
+        return bus_socket_auth_write(b, t);
+}
+
+static int bus_socket_auth_verify_server(sd_bus *b) {
+        char *e;
+        const char *line;
+        size_t l;
+        bool processed = false;
+        int r;
+
+        assert(b);
+
+        if (b->rbuffer_size < 1)
+                return 0;
+
+        /* First char must be a NUL byte */
+        if (*(char*) b->rbuffer != 0)
+                return -EIO;
+
+        if (b->rbuffer_size < 3)
+                return 0;
+
+        /* Begin with the first line */
+        if (b->auth_rbegin <= 0)
+                b->auth_rbegin = 1;
+
+        for (;;) {
+                /* Check if line is complete */
+                line = (char*) b->rbuffer + b->auth_rbegin;
+                e = memmem(line, b->rbuffer_size - b->auth_rbegin, "\r\n", 2);
+                if (!e)
+                        return processed;
+
+                l = e - line;
+
+                if (line_begins(line, l, "AUTH ANONYMOUS")) {
+
+                        r = verify_anonymous_token(b, line + 14, l - 14);
+                        if (r < 0)
+                                return r;
+                        if (r == 0)
+                                r = bus_socket_auth_write(b, "REJECTED\r\n");
+                        else {
+                                b->auth = BUS_AUTH_ANONYMOUS;
+                                r = bus_socket_auth_write_ok(b);
+                        }
+
+                } else if (line_begins(line, l, "AUTH EXTERNAL")) {
+
+                        r = verify_external_token(b, line + 13, l - 13);
+                        if (r < 0)
+                                return r;
+                        if (r == 0)
+                                r = bus_socket_auth_write(b, "REJECTED\r\n");
+                        else {
+                                b->auth = BUS_AUTH_EXTERNAL;
+                                r = bus_socket_auth_write_ok(b);
+                        }
+
+                } else if (line_begins(line, l, "AUTH"))
+                        r = bus_socket_auth_write(b, "REJECTED EXTERNAL ANONYMOUS\r\n");
+                else if (line_equals(line, l, "CANCEL") ||
+                         line_begins(line, l, "ERROR")) {
+
+                        b->auth = _BUS_AUTH_INVALID;
+                        r = bus_socket_auth_write(b, "REJECTED\r\n");
+
+                } else if (line_equals(line, l, "BEGIN")) {
+
+                        if (b->auth == _BUS_AUTH_INVALID)
+                                r = bus_socket_auth_write(b, "ERROR\r\n");
+                        else {
+                                /* We can't leave from the auth phase
+                                 * before we haven't written
+                                 * everything queued, so let's check
+                                 * that */
+
+                                if (bus_socket_auth_needs_write(b))
+                                        return 1;
+
+                                b->rbuffer_size -= (e + 2 - (char*) b->rbuffer);
+                                memmove(b->rbuffer, e + 2, b->rbuffer_size);
+                                return bus_start_running(b);
+                        }
+
+                } else if (line_begins(line, l, "DATA")) {
+
+                        if (b->auth == _BUS_AUTH_INVALID)
+                                r = bus_socket_auth_write(b, "ERROR\r\n");
+                        else {
+                                if (b->auth == BUS_AUTH_ANONYMOUS)
+                                        r = verify_anonymous_token(b, line + 4, l - 4);
+                                else
+                                        r = verify_external_token(b, line + 4, l - 4);
+
+                                if (r < 0)
+                                        return r;
+                                if (r == 0) {
+                                        b->auth = _BUS_AUTH_INVALID;
+                                        r = bus_socket_auth_write(b, "REJECTED\r\n");
+                                } else
+                                        r = bus_socket_auth_write_ok(b);
+                        }
+                } else if (line_equals(line, l, "NEGOTIATE_UNIX_FD")) {
+                        if (b->auth == _BUS_AUTH_INVALID || !(b->hello_flags & KDBUS_HELLO_ACCEPT_FD))
+                                r = bus_socket_auth_write(b, "ERROR\r\n");
+                        else {
+                                b->can_fds = true;
+                                r = bus_socket_auth_write(b, "AGREE_UNIX_FD\r\n");
+                        }
+                } else
+                        r = bus_socket_auth_write(b, "ERROR\r\n");
+
+                if (r < 0)
+                        return r;
+
+                b->auth_rbegin = e + 2 - (char*) b->rbuffer;
+
+                processed = true;
+        }
+}
+
+static int bus_socket_auth_verify(sd_bus *b) {
+        assert(b);
+
+        if (b->is_server)
+                return bus_socket_auth_verify_server(b);
+        else
+                return bus_socket_auth_verify_client(b);
+}
+
+static int bus_socket_read_auth(sd_bus *b) {
+        struct msghdr mh;
+        struct iovec iov = {};
+        size_t n;
+        ssize_t k;
+        int r;
+        void *p;
+        union {
+                struct cmsghdr cmsghdr;
+                uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
+        } control;
+        bool handle_cmsg = false;
+
+        assert(b);
+        assert(b->state == BUS_AUTHENTICATING);
+
+        r = bus_socket_auth_verify(b);
+        if (r != 0)
+                return r;
+
+        n = MAX(256u, b->rbuffer_size * 2);
+
+        if (n > BUS_AUTH_SIZE_MAX)
+                n = BUS_AUTH_SIZE_MAX;
+
+        if (b->rbuffer_size >= n)
+                return -ENOBUFS;
+
+        p = realloc(b->rbuffer, n);
+        if (!p)
+                return -ENOMEM;
+
+        b->rbuffer = p;
+
+        iov.iov_base = (uint8_t*) b->rbuffer + b->rbuffer_size;
+        iov.iov_len = n - b->rbuffer_size;
+
+        if (b->prefer_readv)
+                k = readv(b->input_fd, &iov, 1);
+        else {
+                zero(mh);
+                mh.msg_iov = &iov;
+                mh.msg_iovlen = 1;
+                mh.msg_control = &control;
+                mh.msg_controllen = sizeof(control);
+
+                k = recvmsg(b->input_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
+                if (k < 0 && errno == ENOTSOCK) {
+                        b->prefer_readv = true;
+                        k = readv(b->input_fd, &iov, 1);
+                } else
+                        handle_cmsg = true;
+        }
+        if (k < 0)
+                return errno == EAGAIN ? 0 : -errno;
+        if (k == 0)
+                return -ECONNRESET;
+
+        b->rbuffer_size += k;
+
+        if (handle_cmsg) {
+                struct cmsghdr *cmsg;
+
+                CMSG_FOREACH(cmsg, &mh)
+                        if (cmsg->cmsg_level == SOL_SOCKET &&
+                            cmsg->cmsg_type == SCM_RIGHTS) {
+                                int j;
+
+                                /* Whut? We received fds during the auth
+                                 * protocol? Somebody is playing games with
+                                 * us. Close them all, and fail */
+                                j = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
+                                close_many((int*) CMSG_DATA(cmsg), j);
+                                return -EIO;
+                        } else
+                                log_debug("Got unexpected auxiliary data with level=%d and type=%d",
+                                          cmsg->cmsg_level, cmsg->cmsg_type);
+        }
+
+        r = bus_socket_auth_verify(b);
+        if (r != 0)
+                return r;
+
+        return 1;
+}
+
+void bus_socket_setup(sd_bus *b) {
+        assert(b);
+
+        /* Increase the buffers to 8 MB */
+        fd_inc_rcvbuf(b->input_fd, SNDBUF_SIZE);
+        fd_inc_sndbuf(b->output_fd, SNDBUF_SIZE);
+
+        b->is_kernel = false;
+        b->message_version = 1;
+        b->message_endian = 0;
+}
+
+static void bus_get_peercred(sd_bus *b) {
+        int r;
+
+        assert(b);
+
+        /* Get the peer for socketpair() sockets */
+        b->ucred_valid = getpeercred(b->input_fd, &b->ucred) >= 0;
+
+        /* Get the SELinux context of the peer */
+        if (mac_selinux_have()) {
+                r = getpeersec(b->input_fd, &b->label);
+                if (r < 0 && r != -EOPNOTSUPP)
+                        log_debug_errno(r, "Failed to determine peer security context: %m");
+        }
+}
+
+static int bus_socket_start_auth_client(sd_bus *b) {
+        size_t l;
+        const char *auth_suffix, *auth_prefix;
+
+        assert(b);
+
+        if (b->anonymous_auth) {
+                auth_prefix = "\0AUTH ANONYMOUS ";
+
+                /* For ANONYMOUS auth we send some arbitrary "trace" string */
+                l = 9;
+                b->auth_buffer = hexmem("anonymous", l);
+        } else {
+                char text[DECIMAL_STR_MAX(uid_t) + 1];
+
+                auth_prefix = "\0AUTH EXTERNAL ";
+
+                xsprintf(text, UID_FMT, geteuid());
+
+                l = strlen(text);
+                b->auth_buffer = hexmem(text, l);
+        }
+
+        if (!b->auth_buffer)
+                return -ENOMEM;
+
+        if (b->hello_flags & KDBUS_HELLO_ACCEPT_FD)
+                auth_suffix = "\r\nNEGOTIATE_UNIX_FD\r\nBEGIN\r\n";
+        else
+                auth_suffix = "\r\nBEGIN\r\n";
+
+        b->auth_iovec[0].iov_base = (void*) auth_prefix;
+        b->auth_iovec[0].iov_len = 1 + strlen(auth_prefix + 1);
+        b->auth_iovec[1].iov_base = (void*) b->auth_buffer;
+        b->auth_iovec[1].iov_len = l * 2;
+        b->auth_iovec[2].iov_base = (void*) auth_suffix;
+        b->auth_iovec[2].iov_len = strlen(auth_suffix);
+
+        return bus_socket_write_auth(b);
+}
+
+int bus_socket_start_auth(sd_bus *b) {
+        assert(b);
+
+        bus_get_peercred(b);
+
+        b->state = BUS_AUTHENTICATING;
+        b->auth_timeout = now(CLOCK_MONOTONIC) + BUS_DEFAULT_TIMEOUT;
+
+        if (sd_is_socket(b->input_fd, AF_UNIX, 0, 0) <= 0)
+                b->hello_flags &= ~KDBUS_HELLO_ACCEPT_FD;
+
+        if (b->output_fd != b->input_fd)
+                if (sd_is_socket(b->output_fd, AF_UNIX, 0, 0) <= 0)
+                        b->hello_flags &= ~KDBUS_HELLO_ACCEPT_FD;
+
+        if (b->is_server)
+                return bus_socket_read_auth(b);
+        else
+                return bus_socket_start_auth_client(b);
+}
+
+int bus_socket_connect(sd_bus *b) {
+        int r;
+
+        assert(b);
+        assert(b->input_fd < 0);
+        assert(b->output_fd < 0);
+        assert(b->sockaddr.sa.sa_family != AF_UNSPEC);
+
+        b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (b->input_fd < 0)
+                return -errno;
+
+        b->output_fd = b->input_fd;
+
+        bus_socket_setup(b);
+
+        r = connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size);
+        if (r < 0) {
+                if (errno == EINPROGRESS)
+                        return 1;
+
+                return -errno;
+        }
+
+        return bus_socket_start_auth(b);
+}
+
+int bus_socket_exec(sd_bus *b) {
+        int s[2], r;
+        pid_t pid;
+
+        assert(b);
+        assert(b->input_fd < 0);
+        assert(b->output_fd < 0);
+        assert(b->exec_path);
+
+        r = socketpair(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, s);
+        if (r < 0)
+                return -errno;
+
+        pid = fork();
+        if (pid < 0) {
+                safe_close_pair(s);
+                return -errno;
+        }
+        if (pid == 0) {
+                /* Child */
+
+                (void) reset_all_signal_handlers();
+                (void) reset_signal_mask();
+
+                close_all_fds(s+1, 1);
+
+                assert_se(dup3(s[1], STDIN_FILENO, 0) == STDIN_FILENO);
+                assert_se(dup3(s[1], STDOUT_FILENO, 0) == STDOUT_FILENO);
+
+                if (s[1] != STDIN_FILENO && s[1] != STDOUT_FILENO)
+                        safe_close(s[1]);
+
+                fd_cloexec(STDIN_FILENO, false);
+                fd_cloexec(STDOUT_FILENO, false);
+                fd_nonblock(STDIN_FILENO, false);
+                fd_nonblock(STDOUT_FILENO, false);
+
+                if (b->exec_argv)
+                        execvp(b->exec_path, b->exec_argv);
+                else {
+                        const char *argv[] = { b->exec_path, NULL };
+                        execvp(b->exec_path, (char**) argv);
+                }
+
+                _exit(EXIT_FAILURE);
+        }
+
+        safe_close(s[1]);
+        b->output_fd = b->input_fd = s[0];
+
+        bus_socket_setup(b);
+
+        return bus_socket_start_auth(b);
+}
+
+int bus_socket_take_fd(sd_bus *b) {
+        assert(b);
+
+        bus_socket_setup(b);
+
+        return bus_socket_start_auth(b);
+}
+
+int bus_socket_write_message(sd_bus *bus, sd_bus_message *m, size_t *idx) {
+        struct iovec *iov;
+        ssize_t k;
+        size_t n;
+        unsigned j;
+        int r;
+
+        assert(bus);
+        assert(m);
+        assert(idx);
+        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
+
+        if (*idx >= BUS_MESSAGE_SIZE(m))
+                return 0;
+
+        r = bus_message_setup_iovec(m);
+        if (r < 0)
+                return r;
+
+        n = m->n_iovec * sizeof(struct iovec);
+        iov = alloca(n);
+        memcpy(iov, m->iovec, n);
+
+        j = 0;
+        iovec_advance(iov, &j, *idx);
+
+        if (bus->prefer_writev)
+                k = writev(bus->output_fd, iov, m->n_iovec);
+        else {
+                struct msghdr mh = {
+                        .msg_iov = iov,
+                        .msg_iovlen = m->n_iovec,
+                };
+
+                if (m->n_fds > 0) {
+                        struct cmsghdr *control;
+
+                        mh.msg_control = control = alloca(CMSG_SPACE(sizeof(int) * m->n_fds));
+                        mh.msg_controllen = control->cmsg_len = CMSG_LEN(sizeof(int) * m->n_fds);
+                        control->cmsg_level = SOL_SOCKET;
+                        control->cmsg_type = SCM_RIGHTS;
+                        memcpy(CMSG_DATA(control), m->fds, sizeof(int) * m->n_fds);
+                }
+
+                k = sendmsg(bus->output_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
+                if (k < 0 && errno == ENOTSOCK) {
+                        bus->prefer_writev = true;
+                        k = writev(bus->output_fd, iov, m->n_iovec);
+                }
+        }
+
+        if (k < 0)
+                return errno == EAGAIN ? 0 : -errno;
+
+        *idx += (size_t) k;
+        return 1;
+}
+
+static int bus_socket_read_message_need(sd_bus *bus, size_t *need) {
+        uint32_t a, b;
+        uint8_t e;
+        uint64_t sum;
+
+        assert(bus);
+        assert(need);
+        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
+
+        if (bus->rbuffer_size < sizeof(struct bus_header)) {
+                *need = sizeof(struct bus_header) + 8;
+
+                /* Minimum message size:
+                 *
+                 * Header +
+                 *
+                 *  Method Call: +2 string headers
+                 *       Signal: +3 string headers
+                 * Method Error: +1 string headers
+                 *               +1 uint32 headers
+                 * Method Reply: +1 uint32 headers
+                 *
+                 * A string header is at least 9 bytes
+                 * A uint32 header is at least 8 bytes
+                 *
+                 * Hence the minimum message size of a valid message
+                 * is header + 8 bytes */
+
+                return 0;
+        }
+
+        a = ((const uint32_t*) bus->rbuffer)[1];
+        b = ((const uint32_t*) bus->rbuffer)[3];
+
+        e = ((const uint8_t*) bus->rbuffer)[0];
+        if (e == BUS_LITTLE_ENDIAN) {
+                a = le32toh(a);
+                b = le32toh(b);
+        } else if (e == BUS_BIG_ENDIAN) {
+                a = be32toh(a);
+                b = be32toh(b);
+        } else
+                return -EBADMSG;
+
+        sum = (uint64_t) sizeof(struct bus_header) + (uint64_t) ALIGN_TO(b, 8) + (uint64_t) a;
+        if (sum >= BUS_MESSAGE_SIZE_MAX)
+                return -ENOBUFS;
+
+        *need = (size_t) sum;
+        return 0;
+}
+
+static int bus_socket_make_message(sd_bus *bus, size_t size) {
+        sd_bus_message *t;
+        void *b;
+        int r;
+
+        assert(bus);
+        assert(bus->rbuffer_size >= size);
+        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
+
+        r = bus_rqueue_make_room(bus);
+        if (r < 0)
+                return r;
+
+        if (bus->rbuffer_size > size) {
+                b = memdup((const uint8_t*) bus->rbuffer + size,
+                           bus->rbuffer_size - size);
+                if (!b)
+                        return -ENOMEM;
+        } else
+                b = NULL;
+
+        r = bus_message_from_malloc(bus,
+                                    bus->rbuffer, size,
+                                    bus->fds, bus->n_fds,
+                                    NULL,
+                                    &t);
+        if (r < 0) {
+                free(b);
+                return r;
+        }
+
+        bus->rbuffer = b;
+        bus->rbuffer_size -= size;
+
+        bus->fds = NULL;
+        bus->n_fds = 0;
+
+        bus->rqueue[bus->rqueue_size++] = t;
+
+        return 1;
+}
+
+int bus_socket_read_message(sd_bus *bus) {
+        struct msghdr mh;
+        struct iovec iov = {};
+        ssize_t k;
+        size_t need;
+        int r;
+        void *b;
+        union {
+                struct cmsghdr cmsghdr;
+                uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
+        } control;
+        bool handle_cmsg = false;
+
+        assert(bus);
+        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
+
+        r = bus_socket_read_message_need(bus, &need);
+        if (r < 0)
+                return r;
+
+        if (bus->rbuffer_size >= need)
+                return bus_socket_make_message(bus, need);
+
+        b = realloc(bus->rbuffer, need);
+        if (!b)
+                return -ENOMEM;
+
+        bus->rbuffer = b;
+
+        iov.iov_base = (uint8_t*) bus->rbuffer + bus->rbuffer_size;
+        iov.iov_len = need - bus->rbuffer_size;
+
+        if (bus->prefer_readv)
+                k = readv(bus->input_fd, &iov, 1);
+        else {
+                zero(mh);
+                mh.msg_iov = &iov;
+                mh.msg_iovlen = 1;
+                mh.msg_control = &control;
+                mh.msg_controllen = sizeof(control);
+
+                k = recvmsg(bus->input_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
+                if (k < 0 && errno == ENOTSOCK) {
+                        bus->prefer_readv = true;
+                        k = readv(bus->input_fd, &iov, 1);
+                } else
+                        handle_cmsg = true;
+        }
+        if (k < 0)
+                return errno == EAGAIN ? 0 : -errno;
+        if (k == 0)
+                return -ECONNRESET;
+
+        bus->rbuffer_size += k;
+
+        if (handle_cmsg) {
+                struct cmsghdr *cmsg;
+
+                CMSG_FOREACH(cmsg, &mh)
+                        if (cmsg->cmsg_level == SOL_SOCKET &&
+                            cmsg->cmsg_type == SCM_RIGHTS) {
+                                int n, *f;
+
+                                n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
+
+                                if (!bus->can_fds) {
+                                        /* Whut? We received fds but this
+                                         * isn't actually enabled? Close them,
+                                         * and fail */
+
+                                        close_many((int*) CMSG_DATA(cmsg), n);
+                                        return -EIO;
+                                }
+
+                                f = realloc(bus->fds, sizeof(int) * (bus->n_fds + n));
+                                if (!f) {
+                                        close_many((int*) CMSG_DATA(cmsg), n);
+                                        return -ENOMEM;
+                                }
+
+                                memcpy(f + bus->n_fds, CMSG_DATA(cmsg), n * sizeof(int));
+                                bus->fds = f;
+                                bus->n_fds += n;
+                        } else
+                                log_debug("Got unexpected auxiliary data with level=%d and type=%d",
+                                          cmsg->cmsg_level, cmsg->cmsg_type);
+        }
+
+        r = bus_socket_read_message_need(bus, &need);
+        if (r < 0)
+                return r;
+
+        if (bus->rbuffer_size >= need)
+                return bus_socket_make_message(bus, need);
+
+        return 1;
+}
+
+int bus_socket_process_opening(sd_bus *b) {
+        int error = 0;
+        socklen_t slen = sizeof(error);
+        struct pollfd p = {
+                .fd = b->output_fd,
+                .events = POLLOUT,
+        };
+        int r;
+
+        assert(b->state == BUS_OPENING);
+
+        r = poll(&p, 1, 0);
+        if (r < 0)
+                return -errno;
+
+        if (!(p.revents & (POLLOUT|POLLERR|POLLHUP)))
+                return 0;
+
+        r = getsockopt(b->output_fd, SOL_SOCKET, SO_ERROR, &error, &slen);
+        if (r < 0)
+                b->last_connect_error = errno;
+        else if (error != 0)
+                b->last_connect_error = error;
+        else if (p.revents & (POLLERR|POLLHUP))
+                b->last_connect_error = ECONNREFUSED;
+        else
+                return bus_socket_start_auth(b);
+
+        return bus_next_address(b);
+}
+
+int bus_socket_process_authenticating(sd_bus *b) {
+        int r;
+
+        assert(b);
+        assert(b->state == BUS_AUTHENTICATING);
+
+        if (now(CLOCK_MONOTONIC) >= b->auth_timeout)
+                return -ETIMEDOUT;
+
+        r = bus_socket_write_auth(b);
+        if (r != 0)
+                return r;
+
+        return bus_socket_read_auth(b);
+}