/* gss-misc.c
 * This is a miscellaneous helper class for gss-api features.
 *
 * Copyright 2007-2017 Rainer Gerhards and Adiscon GmbH.
 *
 * This file is part of rsyslog.
 *
 * Rsyslog 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 3 of the License, or
 * (at your option) any later version.
 *
 * Rsyslog 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 Rsyslog.  If not, see <http://www.gnu.org/licenses/>.
 *
 * A copy of the GPL can be found in the file "COPYING" in this distribution.
 */
#include "config.h"
#include "rsyslog.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <fnmatch.h>
#include <assert.h>
#include <errno.h>
#include <ctype.h>
#include <unistd.h>
#include <pthread.h>
#include <gssapi/gssapi.h>
#include "dirty.h"
#include "syslogd-types.h"
#include "srUtils.h"
#include "net.h"
#include "template.h"
#include "msg.h"
#include "module-template.h"
#include "obj.h"
#include "errmsg.h"
#include "gss-misc.h"
#include "gss-token-util.h"
#include "debug.h"
#include "glbl.h"
#include "unlimited_select.h"

MODULE_TYPE_LIB
MODULE_TYPE_NOKEEP;

/* static data */
DEFobjStaticHelpers;
DEFobjCurrIf(glbl)

    static void display_status_(char *m, OM_uint32 code, int type) {
    OM_uint32 maj_stat, min_stat, msg_ctx = 0;
    gss_buffer_desc msg;

    do {
        maj_stat = gss_display_status(&min_stat, code, type, GSS_C_NO_OID, &msg_ctx, &msg);
        if (maj_stat != GSS_S_COMPLETE) {
            LogError(0, NO_ERRCODE, "GSS-API error in gss_display_status called from <%s>\n", m);
            break;
        } else {
            char buf[1024];
            snprintf(buf, sizeof(buf), "GSS-API error %s: %s\n", m, (char *)msg.value);
            buf[sizeof(buf) - 1] = '\0';
            LogError(0, NO_ERRCODE, "%s", buf);
        }
        if (msg.length != 0) gss_release_buffer(&min_stat, &msg);
    } while (msg_ctx);
}


static void display_status(char *m, OM_uint32 maj_stat, OM_uint32 min_stat) {
    display_status_(m, maj_stat, GSS_C_GSS_CODE);
    display_status_(m, min_stat, GSS_C_MECH_CODE);
}


static void display_ctx_flags(OM_uint32 flags) {
    if (flags & GSS_C_DELEG_FLAG) dbgprintf("GSS_C_DELEG_FLAG\n");
    if (flags & GSS_C_MUTUAL_FLAG) dbgprintf("GSS_C_MUTUAL_FLAG\n");
    if (flags & GSS_C_REPLAY_FLAG) dbgprintf("GSS_C_REPLAY_FLAG\n");
    if (flags & GSS_C_SEQUENCE_FLAG) dbgprintf("GSS_C_SEQUENCE_FLAG\n");
    if (flags & GSS_C_CONF_FLAG) dbgprintf("GSS_C_CONF_FLAG\n");
    if (flags & GSS_C_INTEG_FLAG) dbgprintf("GSS_C_INTEG_FLAG\n");
}


static ssize_t read_all(int fd, char *buf, size_t nbyte, time_t deadline) {
    ssize_t ret;
    char *ptr;
    struct timeval tv;
    struct timeval *ptv;
#ifdef USE_UNLIMITED_SELECT
    fd_set *pRfds = malloc(glbl.GetFdSetSize());

    if (pRfds == NULL) return -1;
#else
    fd_set rfds;
    fd_set *pRfds = &rfds;
#endif

    for (ptr = buf; nbyte;) {
        if (deadline != 0) {
            const time_t now = time(NULL);
            if (now == (time_t)-1 || now >= deadline) {
                errno = ETIMEDOUT;
                freeFdSet(pRfds);
                return -1;
            }
            tv.tv_sec = 1;
            tv.tv_usec = 0;
            ptv = &tv;
        } else {
            ptv = NULL;
        }
        FD_ZERO(pRfds);
        FD_SET(fd, pRfds);

        ret = select(fd + 1, pRfds, NULL, NULL, ptv);
        if (ret < 0) {
            if (errno == EINTR) continue;
            freeFdSet(pRfds);
            return ret;
        }
        if (ret == 0) continue;
        if (!FD_ISSET(fd, pRfds)) {
            errno = EIO;
            freeFdSet(pRfds);
            return -1;
        }
        ret = recv(fd, ptr, nbyte, 0);
        if (ret < 0) {
            if (errno == EINTR) continue;
            freeFdSet(pRfds);
            return (ret);
        } else if (ret == 0) {
            freeFdSet(pRfds);
            return (ptr - buf);
        }
        ptr += ret;
        nbyte -= ret;
    }

    freeFdSet(pRfds);
    return (ptr - buf);
}


static int write_all(int fd, char *buf, unsigned int nbyte) {
    int ret;
    char *ptr;

    for (ptr = buf; nbyte;) {
        ret = send(fd, ptr, nbyte, 0);
        if (ret < 0) {
            if (errno == EINTR) continue;
            return (ret);
        } else if (ret == 0) {
            return (ptr - buf);
        }
        ptr += ret;
        nbyte -= ret;
    }

    return (ptr - buf);
}


static int recv_token(int s, gss_buffer_t tok, size_t max_tok_len, unsigned int timeout_secs) {
    ssize_t ret;
    unsigned char lenbuf[4] = "xxx";  // initialized to make clang static analyzer happy
    size_t len = 0;
    time_t deadline = 0;

    assert(tok != NULL);
    tok->length = 0;
    tok->value = NULL;

    if (timeout_secs > 0) {
        deadline = time(NULL);
        if (deadline == (time_t)-1) {
            errno = EIO;
            LogError(errno, NO_ERRCODE, "GSS-API error obtaining current time for token deadline");
            return -1;
        }
        deadline += timeout_secs;
    }

    ret = read_all(s, (char *)lenbuf, 4, deadline);
    if (ret < 0) {
        LogError(0, NO_ERRCODE, "GSS-API error reading token length");
        return -1;
    } else if (!ret) {
        return 0;
    } else if (ret != 4) {
        LogError(0, NO_ERRCODE, "GSS-API error reading token length");
        return -1;
    }

    if (gssTokenDecodeLength(lenbuf, max_tok_len, &len) != RS_RET_OK) {
        LogError(0, NO_ERRCODE, "GSS-API rejecting token length %zu that exceeds limit %zu", len, max_tok_len);
        return -1;
    }
    tok->length = len;

    tok->value = (char *)malloc(tok->length ? tok->length : 1);
    if (tok->length && tok->value == NULL) {
        LogError(0, NO_ERRCODE, "Out of memory allocating token data\n");
        return -1;
    }

    ret = read_all(s, (char *)tok->value, tok->length, deadline);
    if (ret < 0) {
        LogError(0, NO_ERRCODE, "GSS-API error reading token data");
        free(tok->value);
        return -1;
    } else if ((size_t)ret != tok->length) {
        LogError(0, NO_ERRCODE, "GSS-API error reading token data");
        free(tok->value);
        return -1;
    }

    return 1;
}


static int send_token(int s, gss_buffer_t tok) {
    int ret;
    unsigned char lenbuf[4];
    unsigned int len;

    if (tok->length > 0xffffffffUL) {
        LogError(0, NO_ERRCODE, "GSS-API token length %lu exceeds wire format limit", (unsigned long)tok->length);
        return -1;
    }
    len = htonl(tok->length);
    lenbuf[0] = (len >> 24) & 0xff;
    lenbuf[1] = (len >> 16) & 0xff;
    lenbuf[2] = (len >> 8) & 0xff;
    lenbuf[3] = len & 0xff;

    ret = write_all(s, (char *)lenbuf, 4);
    if (ret < 0) {
        LogError(0, NO_ERRCODE, "GSS-API error sending token length");
        return -1;
    } else if (ret != 4) {
        LogError(0, NO_ERRCODE, "GSS-API error sending token length");
        return -1;
    }

    ret = write_all(s, tok->value, tok->length);
    if (ret < 0) {
        LogError(0, NO_ERRCODE, "GSS-API error sending token data");
        return -1;
    } else if (ret != (int)tok->length) {
        LogError(0, NO_ERRCODE, "GSS-API error sending token data");
        return -1;
    }

    return 0;
}


/* queryInterface function
 * rgerhards, 2008-02-29
 */
BEGINobjQueryInterface(gssutil)
    CODESTARTobjQueryInterface(gssutil);
    if (pIf->ifVersion != gssutilCURR_IF_VERSION) { /* check for current version, increment on each change */
        ABORT_FINALIZE(RS_RET_INTERFACE_NOT_SUPPORTED);
    }

    /* ok, we have the right interface, so let's fill it
     * Please note that we may also do some backwards-compatibility
     * work here (if we can support an older interface version - that,
     * of course, also affects the "if" above).
     */
    pIf->recv_token = recv_token;
    pIf->send_token = send_token;
    pIf->display_status = display_status;
    pIf->display_ctx_flags = display_ctx_flags;

finalize_it:
ENDobjQueryInterface(gssutil)


/* exit our class
 * rgerhards, 2008-03-10
 */
BEGINObjClassExit(gssutil, OBJ_IS_LOADABLE_MODULE) /* CHANGE class also in END MACRO! */
    CODESTARTObjClassExit(gssutil);
    /* release objects we no longer need */
    objRelease(glbl, CORE_COMPONENT);
ENDObjClassExit(gssutil)


/* Initialize our class. Must be called as the very first method
 * before anything else is called inside this class.
 * rgerhards, 2008-02-29
 */
BEGINAbstractObjClassInit(gssutil, 1, OBJ_IS_LOADABLE_MODULE) /* class, version - CHANGE class also in END MACRO! */
    /* request objects we use */
    CHKiRet(objUse(glbl, CORE_COMPONENT));
ENDObjClassInit(gssutil)


/* --------------- here now comes the plumbing that makes as a library module --------------- */


BEGINmodExit
    CODESTARTmodExit;
    gssutilClassExit();
ENDmodExit


BEGINqueryEtryPt
    CODESTARTqueryEtryPt;
    CODEqueryEtryPt_STD_LIB_QUERIES;
ENDqueryEtryPt


BEGINmodInit()
    CODESTARTmodInit;
    *ipIFVersProvided = CURR_MOD_IF_VERSION; /* we only support the current interface specification */

    /* Initialize all classes that are in our module - this includes ourselfs */
    CHKiRet(gssutilClassInit(pModInfo)); /* must be done after tcps_sess, as we use it */
ENDmodInit
