/* $OpenBSD: syslogc.c,v 1.19 2021/11/15 15:14:24 millert Exp $ */

/*
 * Copyright (c) 2004 Damien Miller
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>

#include <err.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define DEFAULT_CTLSOCK         "/var/run/syslogd.sock"

#define MAX_MEMBUF_NAME 64      /* Max length of membuf log name */

/*
 * Client protocol NB. all numeric fields in network byte order
 */
#define CTL_VERSION             2

/* Request */
struct ctl_cmd {
        u_int32_t       version;
#define CMD_READ        1       /* Read out log */
#define CMD_READ_CLEAR  2       /* Read and clear log */
#define CMD_CLEAR       3       /* Clear log */
#define CMD_LIST        4       /* List available logs */
#define CMD_FLAGS       5       /* Query flags only */
#define CMD_READ_CONT   6       /* Read out log continuously */
        u_int32_t       cmd;
        u_int32_t       lines;
        char            logname[MAX_MEMBUF_NAME];
};

/* Reply */
struct ctl_reply_hdr {
        u_int32_t       version;
#define CTL_HDR_FLAG_OVERFLOW   0x01
        u_int32_t       flags;
        /* Reply text follows, up to MAX_MEMBUF long */
};

static void
usage(void)
{
        extern char *__progname;

        fprintf(stderr,
            "usage: %s [-Ccfo] [-n lines] [-s reporting_socket] logname\n"
            "       %s -q\n", __progname, __progname);
        exit(1);
}

int
main(int argc, char **argv)
{
        const char *ctlsock_path;
        char buf[8192];
        struct sockaddr_un ctl;
        int ctlsock, ch, oflag, rval;
        FILE *ctlf;
        struct ctl_cmd cc;
        struct ctl_reply_hdr rr;
        const char *errstr;

        memset(&cc, '\0', sizeof(cc));

        ctlsock_path = DEFAULT_CTLSOCK;
        rval = oflag = 0;
        while ((ch = getopt(argc, argv, "Ccfhon:qs:")) != -1) {
                switch (ch) {
                case 'C':
                        cc.cmd = CMD_CLEAR;
                        break;
                case 'c':
                        cc.cmd = CMD_READ_CLEAR;
                        break;
                case 'h':
                        usage();
                        break;
                case 'f':
                        cc.cmd = CMD_READ_CONT;
                        break;
                case 'n':
                        cc.lines = strtonum(optarg, 1, UINT32_MAX, &errstr);
                        if (errstr)
                                errx(1, "number of lines is %s: %s",
                                    errstr, optarg);
                        break;
                case 'o':
                        cc.cmd = CMD_FLAGS;
                        oflag = 1;
                        break;
                case 'q':
                        cc.cmd = CMD_LIST;
                        break;
                case 's':
                        ctlsock_path = optarg;
                        break;
                default:
                        usage();
                        break;
                }
        }

        if (cc.cmd == 0)
                cc.cmd = CMD_READ;

        if ((cc.cmd != CMD_LIST && optind != argc - 1) ||
            (cc.cmd == CMD_LIST && optind != argc))
                usage();

        if (cc.cmd != CMD_LIST) {
                if (strlcpy(cc.logname, argv[optind], sizeof(cc.logname)) >=
                    sizeof(cc.logname))
                        errx(1, "Specified log name is too long");
        }

        memset(&ctl, '\0', sizeof(ctl));
        strlcpy(ctl.sun_path, ctlsock_path, sizeof(ctl.sun_path));
        ctl.sun_family = AF_UNIX;

        if ((ctlsock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
                err(1, "socket");
        if (connect(ctlsock, (struct sockaddr *)&ctl, sizeof(ctl)) == -1)
                err(1, "connect: %s", ctl.sun_path);
        if ((ctlf = fdopen(ctlsock, "r+")) == NULL)
                err(1, "fdopen");

        if (pledge("stdio", NULL) == -1)
                err(1, "stdio");

        cc.version = htonl(CTL_VERSION);
        cc.cmd = htonl(cc.cmd);
        /* Send command */
        if (fwrite(&cc, sizeof(cc), 1, ctlf) != 1)
                err(1, "fwrite");

        fflush(ctlf);
        setvbuf(ctlf, NULL, _IOLBF, 0);
        setvbuf(stdout, NULL, _IOLBF, 0);

        /* Fetch header */
        if (fread(&rr, sizeof(rr), 1, ctlf) != 1)
                err(1, "fread header");

        if (ntohl(rr.version) != CTL_VERSION)
                errx(1, "unsupported syslogd version");

        /* Write out reply */
        while ((fgets(buf, sizeof(buf), ctlf)) != NULL) {
                if (!strcmp(buf, "<ENOBUFS>\n"))
                        fprintf(stderr, "syslogc [%s]: Lines were dropped!\n",
                            cc.logname);
                else
                        fputs(buf, stdout);
        }

        if (oflag && (ntohl(rr.flags) & CTL_HDR_FLAG_OVERFLOW)) {
                printf("%s has overflowed\n", cc.logname);
                rval = 1;
        }

        fclose(ctlf);
        close(ctlsock);

        exit(rval);
}