stdout-bridge: rename logger to stdout-syslog-bridge to make it more descriptive

1 files changed, 694 insertions, 0 deletions

diff --git a/src/stdout-syslog-bridge.c b/src/stdout-syslog-bridge.c
new file mode 100644
index 0000000000..48a301f6a7
--- /dev/null
+++ b/src/stdout-syslog-bridge.c
@@ -0,0 +1,694 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 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
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <assert.h>
+#include <time.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/poll.h>
+#include <sys/epoll.h>
+#include <sys/un.h>
+#include <fcntl.h>
+
+#include "util.h"
+#include "log.h"
+#include "list.h"
+#include "sd-daemon.h"
+#include "tcpwrap.h"
+#include "def.h"
+
+#define STREAMS_MAX 4096
+#define SERVER_FD_MAX 16
+#define TIMEOUT_MSEC ((int) (DEFAULT_EXIT_USEC/USEC_PER_MSEC))
+
+typedef struct Stream Stream;
+
+typedef struct Server {
+        int syslog_fd;
+        int kmsg_fd;
+        int epoll_fd;
+
+        unsigned n_server_fd;
+
+        bool syslog_is_stream;
+
+        LIST_HEAD(Stream, streams);
+        unsigned n_streams;
+} Server;
+
+typedef enum StreamTarget {
+        STREAM_SYSLOG,
+        STREAM_KMSG
+} StreamTarget;
+
+typedef enum StreamState {
+        STREAM_TARGET,
+        STREAM_PRIORITY,
+        STREAM_PROCESS,
+        STREAM_PREFIX,
+        STREAM_RUNNING
+} StreamState;
+
+struct Stream {
+        Server *server;
+
+        StreamState state;
+
+        int fd;
+
+        StreamTarget target;
+        int priority;
+        char *process;
+        pid_t pid;
+        uid_t uid;
+        gid_t gid;
+
+        bool prefix:1;
+        bool tee_console:1;
+
+        char buffer[LINE_MAX];
+        size_t length;
+
+        LIST_FIELDS(Stream, stream);
+};
+
+static int stream_log(Stream *s, char *p, usec_t ts) {
+
+        char header_priority[16], header_time[64], header_pid[16];
+        struct iovec iovec[5];
+        int priority;
+
+        assert(s);
+        assert(p);
+
+        priority = s->priority;
+
+        if (s->prefix)
+                parse_syslog_priority(&p, &priority);
+
+        if (*p == 0)
+                return 0;
+
+        /* Patch in LOG_USER facility if necessary */
+        if ((priority & LOG_FACMASK) == 0)
+                priority = LOG_USER | LOG_PRI(priority);
+
+        /*
+         * The format glibc uses to talk to the syslog daemon is:
+         *
+         *     <priority>time process[pid]: msg
+         *
+         * The format the kernel uses is:
+         *
+         *     <priority>msg\n
+         *
+         *  We extend the latter to include the process name and pid.
+         */
+
+        snprintf(header_priority, sizeof(header_priority), "<%i>", priority);
+        char_array_0(header_priority);
+
+        if (s->target == STREAM_SYSLOG) {
+                time_t t;
+                struct tm *tm;
+
+                t = (time_t) (ts / USEC_PER_SEC);
+                if (!(tm = localtime(&t)))
+                        return -EINVAL;
+
+                if (strftime(header_time, sizeof(header_time), "%h %e %T ", tm) <= 0)
+                        return -EINVAL;
+        }
+
+        snprintf(header_pid, sizeof(header_pid), "[%lu]: ", (unsigned long) s->pid);
+        char_array_0(header_pid);
+
+        zero(iovec);
+        IOVEC_SET_STRING(iovec[0], header_priority);
+
+        if (s->target == STREAM_SYSLOG) {
+                struct msghdr msghdr;
+                union {
+                        struct cmsghdr cmsghdr;
+                        uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
+                } control;
+                struct ucred *ucred;
+
+                zero(control);
+                control.cmsghdr.cmsg_level = SOL_SOCKET;
+                control.cmsghdr.cmsg_type = SCM_CREDENTIALS;
+                control.cmsghdr.cmsg_len = CMSG_LEN(sizeof(struct ucred));
+
+                ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
+                ucred->pid = s->pid;
+                ucred->uid = s->uid;
+                ucred->gid = s->gid;
+
+                IOVEC_SET_STRING(iovec[1], header_time);
+                IOVEC_SET_STRING(iovec[2], s->process);
+                IOVEC_SET_STRING(iovec[3], header_pid);
+                IOVEC_SET_STRING(iovec[4], p);
+
+                /* When using syslog via SOCK_STREAM separate the messages by NUL chars */
+                if (s->server->syslog_is_stream)
+                        iovec[4].iov_len++;
+
+                zero(msghdr);
+                msghdr.msg_iov = iovec;
+                msghdr.msg_iovlen = ELEMENTSOF(iovec);
+                msghdr.msg_control = &control;
+                msghdr.msg_controllen = control.cmsghdr.cmsg_len;
+
+                for (;;) {
+                        ssize_t n;
+
+                        if ((n = sendmsg(s->server->syslog_fd, &msghdr, MSG_NOSIGNAL)) < 0) {
+
+                                if (errno == ESRCH) {
+                                        pid_t our_pid;
+
+                                        /* Hmm, maybe the process this
+                                         * line originates from is
+                                         * dead? Then let's patch in
+                                         * our own pid and retry,
+                                         * since we have nothing
+                                         * better */
+
+                                        our_pid = getpid();
+
+                                        if (ucred->pid != our_pid) {
+                                                ucred->pid = our_pid;
+                                                continue;
+                                        }
+                                }
+
+                                return -errno;
+                        }
+
+                        if (!s->server->syslog_is_stream ||
+                            (size_t) n >= IOVEC_TOTAL_SIZE(iovec, ELEMENTSOF(iovec)))
+                                break;
+
+                        IOVEC_INCREMENT(iovec, ELEMENTSOF(iovec), n);
+                }
+
+        } else if (s->target == STREAM_KMSG) {
+                IOVEC_SET_STRING(iovec[1], s->process);
+                IOVEC_SET_STRING(iovec[2], header_pid);
+                IOVEC_SET_STRING(iovec[3], p);
+                IOVEC_SET_STRING(iovec[4], (char*) "\n");
+
+                if (writev(s->server->kmsg_fd, iovec, ELEMENTSOF(iovec)) < 0)
+                        return -errno;
+        } else
+                assert_not_reached("Unknown log target");
+
+        if (s->tee_console) {
+                int console;
+
+                if ((console = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC)) >= 0) {
+                        IOVEC_SET_STRING(iovec[0], s->process);
+                        IOVEC_SET_STRING(iovec[1], header_pid);
+                        IOVEC_SET_STRING(iovec[2], p);
+                        IOVEC_SET_STRING(iovec[3], (char*) "\n");
+
+                        writev(console, iovec, 4);
+                }
+
+        }
+
+        return 0;
+}
+
+static int stream_line(Stream *s, char *p, usec_t ts) {
+        int r;
+
+        assert(s);
+        assert(p);
+
+        p = strstrip(p);
+
+        switch (s->state) {
+
+        case STREAM_TARGET:
+                if (streq(p, "syslog") || streq(p, "syslog+console"))
+                        s->target = STREAM_SYSLOG;
+                else if (streq(p, "kmsg") || streq(p, "kmsg+console")) {
+
+                        if (s->server->kmsg_fd >= 0 && s->uid == 0)
+                                s->target = STREAM_KMSG;
+                        else {
+                                log_warning("/dev/kmsg logging not available.");
+                                return -EPERM;
+                        }
+                } else {
+                        log_warning("Failed to parse log target line.");
+                        return -EBADMSG;
+                }
+
+                if (endswith(p, "+console"))
+                        s->tee_console = true;
+
+                s->state = STREAM_PRIORITY;
+                return 0;
+
+        case STREAM_PRIORITY:
+                if ((r = safe_atoi(p, &s->priority)) < 0) {
+                        log_warning("Failed to parse log priority line: %m");
+                        return r;
+                }
+
+                if (s->priority < 0) {
+                        log_warning("Log priority negative: %m");
+                        return -ERANGE;
+                }
+
+                s->state = STREAM_PROCESS;
+                return 0;
+
+        case STREAM_PROCESS:
+                if (!(s->process = strdup(p)))
+                        return -ENOMEM;
+
+                s->state = STREAM_PREFIX;
+                return 0;
+
+        case STREAM_PREFIX:
+
+                if ((r = parse_boolean(p)) < 0)
+                        return r;
+
+                s->prefix = r;
+                s->state = STREAM_RUNNING;
+                return 0;
+
+        case STREAM_RUNNING:
+                return stream_log(s, p, ts);
+        }
+
+        assert_not_reached("Unknown stream state");
+}
+
+static int stream_scan(Stream *s, usec_t ts) {
+        char *p;
+        size_t remaining;
+        int r = 0;
+
+        assert(s);
+
+        p = s->buffer;
+        remaining = s->length;
+        for (;;) {
+                char *newline;
+
+                if (!(newline = memchr(p, '\n', remaining)))
+                        break;
+
+                *newline = 0;
+
+                if ((r = stream_line(s, p, ts)) >= 0) {
+                        remaining -= newline-p+1;
+                        p = newline+1;
+                }
+        }
+
+        if (p > s->buffer) {
+                memmove(s->buffer, p, remaining);
+                s->length = remaining;
+        }
+
+        return r;
+}
+
+static int stream_process(Stream *s, usec_t ts) {
+        ssize_t l;
+        int r;
+        assert(s);
+
+        if ((l = read(s->fd, s->buffer+s->length, LINE_MAX-s->length)) < 0) {
+
+                if (errno == EAGAIN)
+                        return 0;
+
+                log_warning("Failed to read from stream: %m");
+                return -errno;
+        }
+
+
+        if (l == 0)
+                return 0;
+
+        s->length += l;
+        r = stream_scan(s, ts);
+
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static void stream_free(Stream *s) {
+        assert(s);
+
+        if (s->server) {
+                assert(s->server->n_streams > 0);
+                s->server->n_streams--;
+                LIST_REMOVE(Stream, stream, s->server->streams, s);
+
+        }
+
+        if (s->fd >= 0) {
+                if (s->server)
+                        epoll_ctl(s->server->epoll_fd, EPOLL_CTL_DEL, s->fd, NULL);
+
+                close_nointr_nofail(s->fd);
+        }
+
+        free(s->process);
+        free(s);
+}
+
+static int stream_new(Server *s, int server_fd) {
+        Stream *stream;
+        int fd;
+        struct ucred ucred;
+        socklen_t len = sizeof(ucred);
+        struct epoll_event ev;
+        int r;
+
+        assert(s);
+
+        if ((fd = accept4(server_fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC)) < 0)
+                return -errno;
+
+        if (s->n_streams >= STREAMS_MAX) {
+                log_warning("Too many connections, refusing connection.");
+                close_nointr_nofail(fd);
+                return 0;
+        }
+
+        if (!socket_tcpwrap(fd, "systemd-stdout-syslog-bridge")) {
+                close_nointr_nofail(fd);
+                return 0;
+        }
+
+        if (!(stream = new0(Stream, 1))) {
+                close_nointr_nofail(fd);
+                return -ENOMEM;
+        }
+
+        stream->fd = fd;
+
+        if (getsockopt(stream->fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        if (shutdown(fd, SHUT_WR) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        zero(ev);
+        ev.data.ptr = stream;
+        ev.events = EPOLLIN;
+        if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        stream->pid = ucred.pid;
+        stream->uid = ucred.uid;
+        stream->gid = ucred.gid;
+
+        stream->server = s;
+        LIST_PREPEND(Stream, stream, s->streams, stream);
+        s->n_streams ++;
+
+        return 0;
+
+fail:
+        stream_free(stream);
+        return r;
+}
+
+static void server_done(Server *s) {
+        unsigned i;
+        assert(s);
+
+        while (s->streams)
+                stream_free(s->streams);
+
+        for (i = 0; i < s->n_server_fd; i++)
+                close_nointr_nofail(SD_LISTEN_FDS_START+i);
+
+        if (s->syslog_fd >= 0)
+                close_nointr_nofail(s->syslog_fd);
+
+        if (s->epoll_fd >= 0)
+                close_nointr_nofail(s->epoll_fd);
+
+        if (s->kmsg_fd >= 0)
+                close_nointr_nofail(s->kmsg_fd);
+}
+
+static int server_init(Server *s, unsigned n_sockets) {
+        int r;
+        unsigned i;
+        union {
+                struct sockaddr sa;
+                struct sockaddr_un un;
+        } sa;
+
+        assert(s);
+        assert(n_sockets > 0);
+
+        zero(*s);
+
+        s->n_server_fd = n_sockets;
+        s->syslog_fd = -1;
+        s->kmsg_fd = -1;
+
+        if ((s->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0) {
+                r = -errno;
+                log_error("Failed to create epoll object: %m");
+                goto fail;
+        }
+
+        for (i = 0; i < n_sockets; i++) {
+                struct epoll_event ev;
+                int fd;
+
+                fd = SD_LISTEN_FDS_START+i;
+
+                if ((r = sd_is_socket(fd, AF_UNSPEC, SOCK_STREAM, 1)) < 0) {
+                        log_error("Failed to determine file descriptor type: %s", strerror(-r));
+                        goto fail;
+                }
+
+                if (!r) {
+                        log_error("Wrong file descriptor type.");
+                        r = -EINVAL;
+                        goto fail;
+                }
+
+                /* We use ev.data.ptr instead of ev.data.fd here,
+                 * since on 64bit archs fd is 32bit while a pointer is
+                 * 64bit. To make sure we can easily distinguish fd
+                 * values and pointer values we want to make sure to
+                 * write the full field unconditionally. */
+
+                zero(ev);
+                ev.events = EPOLLIN;
+                ev.data.ptr = INT_TO_PTR(fd);
+                if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
+                        r = -errno;
+                        log_error("Failed to add server fd to epoll object: %m");
+                        goto fail;
+                }
+        }
+
+        zero(sa);
+        sa.un.sun_family = AF_UNIX;
+        strncpy(sa.un.sun_path, "/dev/log", sizeof(sa.un.sun_path));
+
+        if ((s->syslog_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
+                r = -errno;
+                log_error("Failed to create log fd: %m");
+                goto fail;
+        }
+
+        if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
+                close_nointr_nofail(s->syslog_fd);
+
+                if ((s->syslog_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) < 0) {
+                        r = -errno;
+                        log_error("Failed to create log fd: %m");
+                        goto fail;
+                }
+
+                if (connect(s->syslog_fd, &sa.sa, sizeof(sa)) < 0) {
+                        r = -errno;
+                        log_error("Failed to connect log socket to /dev/log: %m");
+                        goto fail;
+                }
+
+                s->syslog_is_stream = true;
+        } else
+                s->syslog_is_stream = false;
+
+        /* /dev/kmsg logging is strictly optional */
+        if ((s->kmsg_fd = open("/dev/kmsg", O_WRONLY|O_NOCTTY|O_CLOEXEC)) < 0)
+                log_warning("Failed to open /dev/kmsg for logging, disabling kernel log buffer support: %m");
+
+        return 0;
+
+fail:
+        server_done(s);
+        return r;
+}
+
+static int process_event(Server *s, struct epoll_event *ev) {
+        int r;
+
+        assert(s);
+
+        /* Yes, this is a bit ugly, we assume that that valid pointers
+         * are > SD_LISTEN_FDS_START+SERVER_FD_MAX. Which is certainly
+         * true on Linux (and probably most other OSes, too, since the
+         * first 4k usually are part of a separate null pointer
+         * dereference page. */
+
+        if (PTR_TO_INT(ev->data.ptr) >= SD_LISTEN_FDS_START &&
+            PTR_TO_INT(ev->data.ptr) < SD_LISTEN_FDS_START+(int)s->n_server_fd) {
+
+                if (ev->events != EPOLLIN) {
+                        log_info("Got invalid event from epoll. (1)");
+                        return -EIO;
+                }
+
+                if ((r = stream_new(s, PTR_TO_INT(ev->data.ptr))) < 0) {
+                        log_info("Failed to accept new connection: %s", strerror(-r));
+                        return r;
+                }
+
+        } else {
+                usec_t ts;
+                Stream *stream = ev->data.ptr;
+
+                ts = now(CLOCK_REALTIME);
+
+                if (!(ev->events & EPOLLIN)) {
+                        log_info("Got invalid event from epoll. (2)");
+                        stream_free(stream);
+                        return 0;
+                }
+
+                if ((r = stream_process(stream, ts)) <= 0) {
+
+                        if (r < 0)
+                                log_info("Got error on stream: %s", strerror(-r));
+
+                        stream_free(stream);
+                        return 0;
+                }
+        }
+
+        return 0;
+}
+
+int main(int argc, char *argv[]) {
+        Server server;
+        int r = EXIT_FAILURE, n;
+
+        if (getppid() != 1) {
+                log_error("This program should be invoked by init only.");
+                return EXIT_FAILURE;
+        }
+
+        if (argc > 1) {
+                log_error("This program does not take arguments.");
+                return EXIT_FAILURE;
+        }
+
+        log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
+        log_parse_environment();
+        log_open();
+
+        umask(0022);
+
+        if ((n = sd_listen_fds(true)) < 0) {
+                log_error("Failed to read listening file descriptors from environment: %s", strerror(-r));
+                return EXIT_FAILURE;
+        }
+
+        if (n <= 0 || n > SERVER_FD_MAX) {
+                log_error("No or too many file descriptors passed.");
+                return EXIT_FAILURE;
+        }
+
+        if (server_init(&server, (unsigned) n) < 0)
+                return EXIT_FAILURE;
+
+        log_debug("systemd-stdout-syslog-bridge running as pid %lu", (unsigned long) getpid());
+
+        sd_notify(false,
+                  "READY=1\n"
+                  "STATUS=Processing requests...");
+
+        for (;;) {
+                struct epoll_event event;
+                int k;
+
+                if ((k = epoll_wait(server.epoll_fd,
+                                    &event, 1,
+                                    server.n_streams <= 0 ? TIMEOUT_MSEC : -1)) < 0) {
+
+                        if (errno == EINTR)
+                                continue;
+
+                        log_error("epoll_wait() failed: %m");
+                        goto fail;
+                }
+
+                if (k <= 0)
+                        break;
+
+                if (process_event(&server, &event) < 0)
+                        goto fail;
+        }
+
+        r = EXIT_SUCCESS;
+
+        log_debug("systemd-stdout-syslog-bridge stopped as pid %lu", (unsigned long) getpid());
+
+fail:
+        sd_notify(false,
+                  "STATUS=Shutting down...");
+
+        server_done(&server);
+
+        return r;
+}