bus: split socket related code into bus-socket.[ch], to prepare for kdbus backend

1 files changed, 89 insertions, 639 deletions

diff --git a/src/libsystemd-bus/sd-bus.c b/src/libsystemd-bus/sd-bus.c
index 3bdbd11132..6eab4a5469 100644
--- a/src/libsystemd-bus/sd-bus.c
+++ b/src/libsystemd-bus/sd-bus.c
@@ -29,13 +29,13 @@
 
 #include "util.h"
 #include "macro.h"
-#include "missing.h"
 #include "strv.h"
 
 #include "sd-bus.h"
 #include "bus-internal.h"
 #include "bus-message.h"
 #include "bus-type.h"
+#include "bus-socket.h"
 
 static int bus_poll(sd_bus *bus, bool need_more, uint64_t timeout_usec);
 
@@ -250,7 +250,7 @@ static int bus_send_hello(sd_bus *bus) {
         return r;
 }
 
-static int bus_start_running(sd_bus *bus) {
+int bus_start_running(sd_bus *bus) {
         assert(bus);
 
         if (bus->send_hello) {
@@ -648,310 +648,7 @@ static int bus_parse_next_address(sd_bus *b) {
         return 1;
 }
 
-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 bus_write_auth(sd_bus *b) {
-        struct msghdr mh;
-        ssize_t k;
-
-        assert(b);
-        assert(b->state == BUS_AUTHENTICATING);
-
-        if (b->auth_index >= ELEMENTSOF(b->auth_iovec))
-                return 0;
-
-        if (b->auth_timeout == 0)
-                b->auth_timeout = now(CLOCK_MONOTONIC) + BUS_DEFAULT_TIMEOUT;
-
-        zero(mh);
-        mh.msg_iov = b->auth_iovec + b->auth_index;
-        mh.msg_iovlen = ELEMENTSOF(b->auth_iovec) - b->auth_index;
-
-        k = sendmsg(b->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
-        if (k < 0)
-                return errno == EAGAIN ? 0 : -errno;
-
-        iovec_advance(b->auth_iovec, &b->auth_index, (size_t) k);
-
-        return 1;
-}
-
-static int bus_auth_verify(sd_bus *b) {
-        char *e, *f, *start;
-        sd_id128_t peer;
-        unsigned i;
-        int r;
-
-        /* We expect two response lines: "OK" and possibly
-         * "AGREE_UNIX_FD" */
-
-        e = memmem(b->rbuffer, b->rbuffer_size, "\r\n", 2);
-        if (!e)
-                return 0;
-
-        if (b->negotiate_fds) {
-                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;
-
-        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->peer, SD_ID128_NULL) &&
-            !sd_id128_equal(b->peer, peer))
-                return -EPERM;
-
-        b->peer = peer;
-
-        /* And possibly check the second line, too */
-
-        if (f)
-                b->can_fds =
-                        (f - e == sizeof("\r\nAGREE_UNIX_FD") - 1) &&
-                        memcmp(e + 2, "AGREE_UNIX_FD", sizeof("AGREE_UNIX_FD") - 1) == 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 int bus_read_auth(sd_bus *b) {
-        struct msghdr mh;
-        struct iovec iov;
-        size_t n;
-        ssize_t k;
-        int r;
-        void *p;
-
-        assert(b);
-
-        r = bus_auth_verify(b);
-        if (r != 0)
-                return r;
-
-        n = MAX(3 + 32 + 2 + sizeof("AGREE_UNIX_FD") - 1 + 2, 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;
-
-        zero(iov);
-        iov.iov_base = (uint8_t*) b->rbuffer + b->rbuffer_size;
-        iov.iov_len = n - b->rbuffer_size;
-
-        zero(mh);
-        mh.msg_iov = &iov;
-        mh.msg_iovlen = 1;
-
-        k = recvmsg(b->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
-        if (k < 0)
-                return errno == EAGAIN ? 0 : -errno;
-        if (k == 0)
-                return -ECONNRESET;
-
-        b->rbuffer_size += k;
-
-        r = bus_auth_verify(b);
-        if (r != 0)
-                return r;
-
-        return 1;
-}
-
-static int bus_setup_fd(sd_bus *b) {
-        int one;
-
-        assert(b);
-
-        /* Enable SO_PASSCRED + SO_PASSEC. We try this on any socket,
-         * just in case. This is actually irrelavant for */
-        one = 1;
-        setsockopt(b->fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
-        setsockopt(b->fd, SOL_SOCKET, SO_PASSSEC, &one, sizeof(one));
-
-        /* Increase the buffers to a MB */
-        fd_inc_rcvbuf(b->fd, 1024*1024);
-        fd_inc_sndbuf(b->fd, 1024*1024);
-
-        return 0;
-}
-
-static int bus_start_auth(sd_bus *b) {
-        static const char auth_prefix[] = "\0AUTH EXTERNAL ";
-        static const char auth_suffix_with_unix_fd[] = "\r\nNEGOTIATE_UNIX_FD\r\nBEGIN\r\n";
-        static const char auth_suffix_without_unix_fd[] = "\r\nBEGIN\r\n";
-
-        char text[20 + 1]; /* enough space for a 64bit integer plus NUL */
-        size_t l;
-        const char *auth_suffix;
-        int domain = 0, r;
-        socklen_t sl;
-
-        assert(b);
-
-        b->state = BUS_AUTHENTICATING;
-
-        sl = sizeof(domain);
-        r = getsockopt(b->fd, SOL_SOCKET, SO_DOMAIN, &domain, &sl);
-        if (r < 0)
-                return -errno;
-
-        if (domain != AF_UNIX)
-                b->negotiate_fds = false;
-
-        snprintf(text, sizeof(text), "%llu", (unsigned long long) geteuid());
-        char_array_0(text);
-
-        l = strlen(text);
-        b->auth_uid = hexmem(text, l);
-        if (!b->auth_uid)
-                return -ENOMEM;
-
-        auth_suffix = b->negotiate_fds ? auth_suffix_with_unix_fd : auth_suffix_without_unix_fd;
-
-        b->auth_iovec[0].iov_base = (void*) auth_prefix;
-        b->auth_iovec[0].iov_len = sizeof(auth_prefix) -1;
-        b->auth_iovec[1].iov_base = (void*) b->auth_uid;
-        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);
-        b->auth_size = sizeof(auth_prefix) - 1 + l * 2 + sizeof(auth_suffix) - 1;
-
-        return bus_write_auth(b);
-}
-
-static int bus_connect(sd_bus *b) {
-        int r;
-
-        assert(b);
-        assert(b->fd < 0);
-        assert(b->sockaddr.sa.sa_family != AF_UNSPEC);
-
-        b->fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
-        if (b->fd < 0)
-                return -errno;
-
-        r = bus_setup_fd(b);
-        if (r < 0)
-                return r;
-
-        r = connect(b->fd, &b->sockaddr.sa, b->sockaddr_size);
-        if (r < 0) {
-                if (errno == EINPROGRESS)
-                        return 1;
-
-                return -errno;
-        }
-
-        return bus_start_auth(b);
-}
-
-static int bus_exec(sd_bus *b) {
-        int s[2];
-        pid_t pid;
-
-        assert(b);
-        assert(b->fd < 0);
-        assert(b->exec_path);
-
-        b->fd = socketpair(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, s);
-        if (b->fd < 0)
-                return -errno;
-
-        pid = fork();
-        if (pid < 0) {
-                close_pipe(s);
-                return -errno;
-        }
-        if (pid == 0) {
-                /* Child */
-
-                close_all_fds(s, 2);
-                close_nointr_nofail(s[0]);
-
-                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)
-                        close_nointr_nofail(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);
-        }
-
-        close_nointr_nofail(s[1]);
-        b->fd = s[0];
-
-        return bus_start_auth(b);
-}
-
-static int bus_start_connect(sd_bus *b) {
+static int bus_start_address(sd_bus *b) {
         int r;
 
         assert(b);
@@ -963,7 +660,8 @@ static int bus_start_connect(sd_bus *b) {
                 }
 
                 if (b->sockaddr.sa.sa_family != AF_UNSPEC) {
-                        r = bus_connect(b);
+
+                        r = bus_socket_connect(b);
                         if (r >= 0)
                                 return r;
 
@@ -971,7 +669,7 @@ static int bus_start_connect(sd_bus *b) {
 
                 } else if (b->exec_path) {
 
-                        r = bus_exec(b);
+                        r = bus_socket_exec(b);
                         if (r >= 0)
                                 return r;
 
@@ -986,6 +684,13 @@ static int bus_start_connect(sd_bus *b) {
         }
 }
 
+int bus_next_address(sd_bus *b) {
+        assert(b);
+
+        bus_reset_parsed_address(b);
+        return bus_start_address(b);
+}
+
 static int bus_start_fd(sd_bus *b) {
         int r;
 
@@ -999,11 +704,7 @@ static int bus_start_fd(sd_bus *b) {
         if (r < 0)
                 return r;
 
-        r = bus_setup_fd(b);
-        if (r < 0)
-                return r;
-
-        return bus_start_auth(b);
+        return bus_socket_take_fd(b);
 }
 
 int sd_bus_start(sd_bus *bus) {
@@ -1019,7 +720,7 @@ int sd_bus_start(sd_bus *bus) {
         if (bus->fd >= 0)
                 r = bus_start_fd(bus);
         else if (bus->address)
-                r = bus_start_connect(bus);
+                r = bus_start_address(bus);
         else
                 return -EINVAL;
 
@@ -1206,234 +907,6 @@ static int bus_seal_message(sd_bus *b, sd_bus_message *m) {
         return bus_message_seal(m, ++b->serial);
 }
 
-static int message_write(sd_bus *bus, sd_bus_message *m, size_t *idx) {
-        struct msghdr mh;
-        struct iovec *iov;
-        ssize_t k;
-        size_t n;
-        unsigned j;
-
-        assert(bus);
-        assert(m);
-        assert(idx);
-        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
-
-        if (*idx >= m->size)
-                return 0;
-        zero(mh);
-
-        if (m->n_fds > 0) {
-                struct cmsghdr *control;
-                control = alloca(CMSG_SPACE(sizeof(int) * m->n_fds));
-
-                mh.msg_control = control;
-                control->cmsg_level = SOL_SOCKET;
-                control->cmsg_type = SCM_RIGHTS;
-                mh.msg_controllen = control->cmsg_len = CMSG_LEN(sizeof(int) * m->n_fds);
-                memcpy(CMSG_DATA(control), m->fds, sizeof(int) * m->n_fds);
-        }
-
-        n = m->n_iovec * sizeof(struct iovec);
-        iov = alloca(n);
-        memcpy(iov, m->iovec, n);
-
-        j = 0;
-        iovec_advance(iov, &j, *idx);
-
-        mh.msg_iov = iov;
-        mh.msg_iovlen = m->n_iovec;
-
-        k = sendmsg(bus->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
-        if (k < 0)
-                return errno == EAGAIN ? 0 : -errno;
-
-        *idx += (size_t) k;
-        return 1;
-}
-
-static int message_read_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 == SD_BUS_LITTLE_ENDIAN) {
-                a = le32toh(a);
-                b = le32toh(b);
-        } else if (e == SD_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 message_make(sd_bus *bus, size_t size, sd_bus_message **m) {
-        sd_bus_message *t;
-        void *b;
-        int r;
-
-        assert(bus);
-        assert(m);
-        assert(bus->rbuffer_size >= size);
-        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
-
-        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->rbuffer, size,
-                                    bus->fds, bus->n_fds,
-                                    bus->ucred_valid ? &bus->ucred : NULL,
-                                    bus->label[0] ? bus->label : NULL,
-                                    &t);
-        if (r < 0) {
-                free(b);
-                return r;
-        }
-
-        bus->rbuffer = b;
-        bus->rbuffer_size -= size;
-
-        bus->fds = NULL;
-        bus->n_fds = 0;
-
-        *m = t;
-        return 1;
-}
-
-static int message_read(sd_bus *bus, sd_bus_message **m) {
-        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) +
-                            CMSG_SPACE(sizeof(struct ucred)) +
-                            CMSG_SPACE(NAME_MAX)]; /*selinux label */
-        } control;
-        struct cmsghdr *cmsg;
-
-        assert(bus);
-        assert(m);
-        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
-
-        r = message_read_need(bus, &need);
-        if (r < 0)
-                return r;
-
-        if (bus->rbuffer_size >= need)
-                return message_make(bus, need, m);
-
-        b = realloc(bus->rbuffer, need);
-        if (!b)
-                return -ENOMEM;
-
-        bus->rbuffer = b;
-
-        zero(iov);
-        iov.iov_base = (uint8_t*) bus->rbuffer + bus->rbuffer_size;
-        iov.iov_len = need - bus->rbuffer_size;
-
-        zero(mh);
-        mh.msg_iov = &iov;
-        mh.msg_iovlen = 1;
-        mh.msg_control = &control;
-        mh.msg_controllen = sizeof(control);
-
-        k = recvmsg(bus->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
-        if (k < 0)
-                return errno == EAGAIN ? 0 : -errno;
-        if (k == 0)
-                return -ECONNRESET;
-
-        bus->rbuffer_size += k;
-
-        for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) {
-                if (cmsg->cmsg_level == SOL_SOCKET &&
-                    cmsg->cmsg_type == SCM_RIGHTS) {
-                        int n, *f;
-
-                        n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
-
-                        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 if (cmsg->cmsg_level == SOL_SOCKET &&
-                    cmsg->cmsg_type == SCM_CREDENTIALS &&
-                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
-
-                        memcpy(&bus->ucred, CMSG_DATA(cmsg), sizeof(struct ucred));
-                        bus->ucred_valid = true;
-
-                } else if (cmsg->cmsg_level == SOL_SOCKET &&
-                         cmsg->cmsg_type == SCM_SECURITY) {
-
-                        size_t l;
-                        l = cmsg->cmsg_len - CMSG_LEN(0);
-                        memcpy(&bus->label, CMSG_DATA(cmsg), l);
-                        bus->label[l] = 0;
-                }
-        }
-
-        r = message_read_need(bus, &need);
-        if (r < 0)
-                return r;
-
-        if (bus->rbuffer_size >= need)
-                return message_make(bus, need, m);
-
-        return 1;
-}
-
 static int dispatch_wqueue(sd_bus *bus) {
         int r, ret = 0;
 
@@ -1445,7 +918,7 @@ static int dispatch_wqueue(sd_bus *bus) {
 
         while (bus->wqueue_size > 0) {
 
-                r = message_write(bus, bus->wqueue[0], &bus->windex);
+                r = bus_socket_write_message(bus, bus->wqueue[0], &bus->windex);
                 if (r < 0) {
                         sd_bus_close(bus);
                         return r;
@@ -1497,7 +970,7 @@ static int dispatch_rqueue(sd_bus *bus, sd_bus_message **m) {
 
         /* Try to read a new message */
         do {
-                r = message_read(bus, &z);
+                r = bus_socket_read_message(bus, &z);
                 if (r < 0) {
                         sd_bus_close(bus);
                         return r;
@@ -1549,7 +1022,7 @@ int sd_bus_send(sd_bus *bus, sd_bus_message *m, uint64_t *serial) {
         if ((bus->state == BUS_RUNNING || bus->state == BUS_HELLO) && bus->wqueue_size <= 0) {
                 size_t idx = 0;
 
-                r = message_write(bus, m, &idx);
+                r = bus_socket_write_message(bus, m, &idx);
                 if (r < 0) {
                         sd_bus_close(bus);
                         return r;
@@ -1791,7 +1264,7 @@ int sd_bus_send_with_reply_and_block(
                         room = true;
                 }
 
-                r = message_read(bus, &incoming);
+                r = bus_socket_read_message(bus, &incoming);
                 if (r < 0)
                         return r;
                 if (incoming) {
@@ -2119,126 +1592,103 @@ static int process_message(sd_bus *bus, sd_bus_message *m) {
         return process_object(bus, m);
 }
 
-int sd_bus_process(sd_bus *bus, sd_bus_message **ret) {
+static int process_running(sd_bus *bus, sd_bus_message **ret) {
+        _cleanup_bus_message_unref_ sd_bus_message *m = NULL;
         int r;
 
-        /* Returns 0 when we didn't do anything. This should cause the
-         * caller to invoke sd_bus_wait() before returning the next
-         * time. Returns > 0 when we did something, which possibly
-         * means *ret is filled in with an unprocessed message. */
-
-        if (!bus)
-                return -EINVAL;
-        if (bus->state == BUS_UNSET)
-                return -ENOTCONN;
-        if (bus->fd < 0)
-                return -ENOTCONN;
+        assert(bus);
+        assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
 
-        if (bus->state == BUS_OPENING) {
-                struct pollfd p;
+        r = process_timeout(bus);
+        if (r != 0)
+                goto null_message;
 
-                zero(p);
-                p.fd = bus->fd;
-                p.events = POLLOUT;
+        r = dispatch_wqueue(bus);
+        if (r != 0)
+                goto null_message;
 
-                r = poll(&p, 1, 0);
-                if (r < 0)
-                        return -errno;
+        r = dispatch_rqueue(bus, &m);
+        if (r < 0)
+                return r;
+        if (!m)
+                goto null_message;
 
-                if (p.revents & (POLLOUT|POLLERR|POLLHUP)) {
-                        int error = 0;
-                        socklen_t slen = sizeof(error);
+        r = process_message(bus, m);
+        if (r != 0)
+                goto null_message;
 
-                        r = getsockopt(bus->fd, SOL_SOCKET, SO_ERROR, &error, &slen);
-                        if (r < 0)
-                                bus->last_connect_error = errno;
-                        else if (error != 0)
-                                bus->last_connect_error = error;
-                        else if (p.revents & (POLLERR|POLLHUP))
-                                bus->last_connect_error = ECONNREFUSED;
-                        else {
-                                r = bus_start_auth(bus);
-                                goto null_message;
-                        }
+        if (ret) {
+                *ret = m;
+                m = NULL;
+                return 1;
+        }
 
-                        /* Try next address */
-                        bus_reset_parsed_address(bus);
-                        r = bus_start_connect(bus);
-                        goto null_message;
-                }
+        if (m->header->type == SD_BUS_MESSAGE_TYPE_METHOD_CALL) {
+                _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
+                _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_INIT;
 
-                r = 0;
-                goto null_message;
+                sd_bus_error_set(&error, "org.freedesktop.DBus.Error.UnknownObject", "Unknown object '%s'.", m->path);
 
-        } else if (bus->state == BUS_AUTHENTICATING) {
+                r = sd_bus_message_new_method_error(bus, m, &error, &reply);
+                if (r < 0)
+                        return r;
 
-                if (now(CLOCK_MONOTONIC) >= bus->auth_timeout)
-                        return -ETIMEDOUT;
+                r = sd_bus_send(bus, reply, NULL);
+                if (r < 0)
+                        return r;
+        }
 
-                r = bus_write_auth(bus);
-                if (r != 0)
-                        goto null_message;
+        return 1;
 
-                r = bus_read_auth(bus);
-                goto null_message;
+null_message:
+        if (r >= 0 && ret)
+                *ret = NULL;
 
-        } else if (bus->state == BUS_RUNNING || bus->state == BUS_HELLO) {
-                _cleanup_bus_message_unref_ sd_bus_message *m = NULL;
-                int k;
+        return r;
+}
 
-                r = process_timeout(bus);
-                if (r != 0)
-                        goto null_message;
+int sd_bus_process(sd_bus *bus, sd_bus_message **ret) {
+        int r;
 
-                r = dispatch_wqueue(bus);
-                if (r != 0)
-                        goto null_message;
+        /* Returns 0 when we didn't do anything. This should cause the
+         * caller to invoke sd_bus_wait() before returning the next
+         * time. Returns > 0 when we did something, which possibly
+         * means *ret is filled in with an unprocessed message. */
 
-                k = r;
-                r = dispatch_rqueue(bus, &m);
-                if (r < 0)
-                        return r;
-                if (!m) {
-                        if (r == 0)
-                                r = k;
-                        goto null_message;
-                }
+        if (!bus)
+                return -EINVAL;
+        if (bus->fd < 0)
+                return -ENOTCONN;
 
-                r = process_message(bus, m);
-                if (r != 0)
-                        goto null_message;
+        switch (bus->state) {
 
-                if (ret) {
-                        *ret = m;
-                        m = NULL;
-                        return 1;
-                }
+        case BUS_UNSET:
+                return -ENOTCONN;
 
-                if (m->header->type == SD_BUS_MESSAGE_TYPE_METHOD_CALL) {
-                        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-                        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_INIT;
+        case BUS_OPENING:
+                r = bus_socket_process_opening(bus);
+                if (r < 0)
+                        return r;
+                if (ret)
+                        *ret = NULL;
+                return r;
 
-                        sd_bus_error_set(&error, "org.freedesktop.DBus.Error.UnknownObject", "Unknown object '%s'.", m->path);
+        case BUS_AUTHENTICATING:
 
-                        r = sd_bus_message_new_method_error(bus, m, &error, &reply);
-                        if (r < 0)
-                                return r;
+                r = bus_socket_process_authenticating(bus);
+                if (r < 0)
+                        return r;
+                if (ret)
+                        *ret = NULL;
+                return r;
 
-                        r = sd_bus_send(bus, reply, NULL);
-                        if (r < 0)
-                                return r;
-                }
+        case BUS_RUNNING:
+        case BUS_HELLO:
 
-                return 1;
+                return process_running(bus, ret);
         }
 
         assert_not_reached("Unknown state");
-
-null_message:
-        if (r >= 0 && ret)
-                *ret = NULL;
-
-        return r;
 }
 
 static int bus_poll(sd_bus *bus, bool need_more, uint64_t timeout_usec) {