/*
 * 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.
 */

#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 */