common/nameser/ns_sign.c

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1999 by Internet Software Consortium, Inc.
 *
 * 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 ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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.
 */

#ifndef lint
static const char rcsid[] = "$Id: ns_sign.c,v 1.6 2006/03/09 23:57:56 marka Exp $";
#endif

/* Import. */

#include "port_before.h"
#include "fd_setsize.h"

#include <sys/types.h>
#include <sys/param.h>

#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>

#include <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <isc/dst.h>
#include <isc/assertions.h>

#include "port_after.h"

#define BOUNDS_CHECK(ptr, count) \
    do { \
        if ((ptr) + (count) > eob) { \
            errno = EMSGSIZE; \
            return(NS_TSIG_ERROR_NO_SPACE); \
        } \
    } while (0)

/*%
 *  ns_sign
 *
 * Parameters:
 *\li   msg     message to be sent
 *\li   msglen      input - length of message
 *          output - length of signed message
 *\li   msgsize     length of buffer containing message
 *\li   error       value to put in the error field
 *\li   key     tsig key used for signing
 *\li   querysig    (response), the signature in the query
 *\li   querysiglen (response), the length of the signature in the query
 *\li   sig     a buffer to hold the generated signature
 *\li   siglen      input - length of signature buffer
 *          output - length of signature
 *
 * Errors:
 *\li   - bad input data (-1)
 *\li   - bad key / sign failed (-BADKEY)
 *\li   - not enough space (NS_TSIG_ERROR_NO_SPACE)
 */
int
ns_sign(u_char *msg, int *msglen, int msgsize, int error, void *k,
    const u_char *querysig, int querysiglen, u_char *sig, int *siglen,
    time_t in_timesigned)
{
    return(ns_sign2(msg, msglen, msgsize, error, k,
            querysig, querysiglen, sig, siglen,
            in_timesigned, NULL, NULL));
}

int
ns_sign2(u_char *msg, int *msglen, int msgsize, int error, void *k,
     const u_char *querysig, int querysiglen, u_char *sig, int *siglen,
     time_t in_timesigned, u_char **dnptrs, u_char **lastdnptr)
{
    HEADER *hp = (HEADER *)msg;
    DST_KEY *key = (DST_KEY *)k;
    u_char *cp, *eob;
    u_char *lenp;
    u_char *alg;
    int n;
    time_t timesigned;
        u_char name[NS_MAXCDNAME];

    dst_init();
    if (msg == NULL || msglen == NULL || sig == NULL || siglen == NULL)
        return (-1);

    cp = msg + *msglen;
    eob = msg + msgsize;

    /* Name. */
    if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
        n = ns_name_pton(key->dk_key_name, name, sizeof name);
        if (n != -1)
            n = ns_name_pack(name, cp, eob - cp,
                     (const u_char **)dnptrs,
                     (const u_char **)lastdnptr);

    } else {
        n = ns_name_pton("", name, sizeof name);
        if (n != -1)
            n = ns_name_pack(name, cp, eob - cp, NULL, NULL);
    }
    if (n < 0)
        return (NS_TSIG_ERROR_NO_SPACE);
    cp += n;

    /* Type, class, ttl, length (not filled in yet). */
    BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
    PUTSHORT(ns_t_tsig, cp);
    PUTSHORT(ns_c_any, cp);
    PUTLONG(0, cp);     /*%< TTL */
    lenp = cp;
    cp += 2;

    /* Alg. */
    if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
        if (key->dk_alg != KEY_HMAC_MD5)
            return (-ns_r_badkey);
        n = dn_comp(NS_TSIG_ALG_HMAC_MD5, cp, eob - cp, NULL, NULL);
    }
    else
        n = dn_comp("", cp, eob - cp, NULL, NULL);
    if (n < 0)
        return (NS_TSIG_ERROR_NO_SPACE);
    alg = cp;
    cp += n;

    /* Time. */
    BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
    PUTSHORT(0, cp);
    timesigned = time(NULL);
    if (error != ns_r_badtime)
        PUTLONG(timesigned, cp);
    else
        PUTLONG(in_timesigned, cp);
    PUTSHORT(NS_TSIG_FUDGE, cp);

    /* Compute the signature. */
    if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
        void *ctx;
        u_char buf[NS_MAXCDNAME], *cp2;
        int n;

        dst_sign_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0);

        /* Digest the query signature, if this is a response. */
        if (querysiglen > 0 && querysig != NULL) {
            u_int16_t len_n = htons(querysiglen);
            dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
                      (u_char *)&len_n, INT16SZ, NULL, 0);
            dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
                      querysig, querysiglen, NULL, 0);
        }

        /* Digest the message. */
        dst_sign_data(SIG_MODE_UPDATE, key, &ctx, msg, *msglen,
                  NULL, 0);

        /* Digest the key name. */
        n = ns_name_ntol(name, buf, sizeof(buf));
        INSIST(n > 0);
        dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);

        /* Digest the class and TTL. */
        cp2 = buf;
        PUTSHORT(ns_c_any, cp2);
        PUTLONG(0, cp2);
        dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, cp2-buf,
                  NULL, 0);

        /* Digest the algorithm. */
        n = ns_name_ntol(alg, buf, sizeof(buf));
        INSIST(n > 0);
        dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);

        /* Digest the time signed, fudge, error, and other data */
        cp2 = buf;
        PUTSHORT(0, cp2);   /*%< Top 16 bits of time */
        if (error != ns_r_badtime)
            PUTLONG(timesigned, cp2);
        else
            PUTLONG(in_timesigned, cp2);
        PUTSHORT(NS_TSIG_FUDGE, cp2);
        PUTSHORT(error, cp2);   /*%< Error */
        if (error != ns_r_badtime)
            PUTSHORT(0, cp2);   /*%< Other data length */
        else {
            PUTSHORT(INT16SZ+INT32SZ, cp2); /*%< Other data length */
            PUTSHORT(0, cp2);   /*%< Top 16 bits of time */
            PUTLONG(timesigned, cp2);
        }
        dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, cp2-buf,
                  NULL, 0);

        n = dst_sign_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,
                  sig, *siglen);
        if (n < 0)
            return (-ns_r_badkey);
        *siglen = n;
    } else
        *siglen = 0;

    /* Add the signature. */
    BOUNDS_CHECK(cp, INT16SZ + (*siglen));
    PUTSHORT(*siglen, cp);
    memcpy(cp, sig, *siglen);
    cp += (*siglen);

    /* The original message ID & error. */
    BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
    PUTSHORT(ntohs(hp->id), cp);    /*%< already in network order */
    PUTSHORT(error, cp);

    /* Other data. */
    BOUNDS_CHECK(cp, INT16SZ);
    if (error != ns_r_badtime)
        PUTSHORT(0, cp);    /*%< Other data length */
    else {
        PUTSHORT(INT16SZ+INT32SZ, cp);  /*%< Other data length */
        BOUNDS_CHECK(cp, INT32SZ+INT16SZ);
        PUTSHORT(0, cp);    /*%< Top 16 bits of time */
        PUTLONG(timesigned, cp);
    }

    /* Go back and fill in the length. */
    PUTSHORT(cp - lenp - INT16SZ, lenp);

    hp->arcount = htons(ntohs(hp->arcount) + 1);
    *msglen = (cp - msg);
    return (0);
}

int
ns_sign_tcp_init(void *k, const u_char *querysig, int querysiglen,
         ns_tcp_tsig_state *state)
{
    dst_init();
    if (state == NULL || k == NULL || querysig == NULL || querysiglen < 0)
        return (-1);
    state->counter = -1;
    state->key = k;
    if (state->key->dk_alg != KEY_HMAC_MD5)
        return (-ns_r_badkey);
    if (querysiglen > (int)sizeof(state->sig))
        return (-1);
    memcpy(state->sig, querysig, querysiglen);
    state->siglen = querysiglen;
    return (0);
}

int
ns_sign_tcp(u_char *msg, int *msglen, int msgsize, int error,
        ns_tcp_tsig_state *state, int done)
{
    return (ns_sign_tcp2(msg, msglen, msgsize, error, state,
                 done, NULL, NULL));
}

int
ns_sign_tcp2(u_char *msg, int *msglen, int msgsize, int error,
         ns_tcp_tsig_state *state, int done,
         u_char **dnptrs, u_char **lastdnptr)
{
    u_char *cp, *eob, *lenp;
    u_char buf[MAXDNAME], *cp2;
    HEADER *hp = (HEADER *)msg;
    time_t timesigned;
    int n;

    if (msg == NULL || msglen == NULL || state == NULL)
        return (-1);

    state->counter++;
    if (state->counter == 0)
        return (ns_sign2(msg, msglen, msgsize, error, state->key,
                 state->sig, state->siglen,
                 state->sig, &state->siglen, 0,
                 dnptrs, lastdnptr));

    if (state->siglen > 0) {
        u_int16_t siglen_n = htons(state->siglen);
        dst_sign_data(SIG_MODE_INIT, state->key, &state->ctx,
                  NULL, 0, NULL, 0);
        dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
                  (u_char *)&siglen_n, INT16SZ, NULL, 0);
        dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
                  state->sig, state->siglen, NULL, 0);
        state->siglen = 0;
    }

    dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx, msg, *msglen,
              NULL, 0);

    if (done == 0 && (state->counter % 100 != 0))
        return (0);

    cp = msg + *msglen;
    eob = msg + msgsize;

    /* Name. */
    n = dn_comp(state->key->dk_key_name, cp, eob - cp, dnptrs, lastdnptr);
    if (n < 0)
        return (NS_TSIG_ERROR_NO_SPACE);
    cp += n;

    /* Type, class, ttl, length (not filled in yet). */
    BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
    PUTSHORT(ns_t_tsig, cp);
    PUTSHORT(ns_c_any, cp);
    PUTLONG(0, cp);     /*%< TTL */
    lenp = cp;
    cp += 2;

    /* Alg. */
    n = dn_comp(NS_TSIG_ALG_HMAC_MD5, cp, eob - cp, NULL, NULL);
    if (n < 0)
        return (NS_TSIG_ERROR_NO_SPACE);
    cp += n;

    /* Time. */
    BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
    PUTSHORT(0, cp);
    timesigned = time(NULL);
    PUTLONG(timesigned, cp);
    PUTSHORT(NS_TSIG_FUDGE, cp);

    /*
     * Compute the signature.
     */

    /* Digest the time signed and fudge. */
    cp2 = buf;
    PUTSHORT(0, cp2);   /*%< Top 16 bits of time */
    PUTLONG(timesigned, cp2);
    PUTSHORT(NS_TSIG_FUDGE, cp2);

    dst_sign_data(SIG_MODE_UPDATE, state->key, &state->ctx,
              buf, cp2 - buf, NULL, 0);

    n = dst_sign_data(SIG_MODE_FINAL, state->key, &state->ctx, NULL, 0,
              state->sig, sizeof(state->sig));
    if (n < 0)
        return (-ns_r_badkey);
    state->siglen = n;

    /* Add the signature. */
    BOUNDS_CHECK(cp, INT16SZ + state->siglen);
    PUTSHORT(state->siglen, cp);
    memcpy(cp, state->sig, state->siglen);
    cp += state->siglen;

    /* The original message ID & error. */
    BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
    PUTSHORT(ntohs(hp->id), cp);    /*%< already in network order */
    PUTSHORT(error, cp);

    /* Other data. */
    BOUNDS_CHECK(cp, INT16SZ);
    PUTSHORT(0, cp);

    /* Go back and fill in the length. */
    PUTSHORT(cp - lenp - INT16SZ, lenp);

    hp->arcount = htons(ntohs(hp->arcount) + 1);
    *msglen = (cp - msg);
    return (0);
}

/*! \file */