common/dst/dst_api.c

#ifndef LINT
static const char rcsid[] = "$Header: /proj/cvs/prod/libbind/dst/dst_api.c,v 1.17 2007/09/24 17:18:25 each Exp $";
#endif

/*
 * Portions Copyright (c) 1995-1998 by Trusted Information Systems, 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 TRUSTED INFORMATION SYSTEMS
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL
 * TRUSTED INFORMATION SYSTEMS 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 THE SOFTWARE.
 */
/*
 * This file contains the interface between the DST API and the crypto API.
 * This is the only file that needs to be changed if the crypto system is
 * changed.  Exported functions are:
 * void dst_init()   Initialize the toolkit
 * int  dst_check_algorithm()   Function to determines if alg is suppored.
 * int  dst_compare_keys()      Function to compare two keys for equality.
 * int  dst_sign_data()         Incremental signing routine.
 * int  dst_verify_data()       Incremental verify routine.
 * int  dst_generate_key()      Function to generate new KEY
 * DST_KEY *dst_read_key()      Function to retrieve private/public KEY.
 * void dst_write_key()         Function to write out a key.
 * DST_KEY *dst_dnskey_to_key() Function to convert DNS KEY RR to a DST
 *              KEY structure.
 * int dst_key_to_dnskey()  Function to return a public key in DNS
 *              format binary
 * DST_KEY *dst_buffer_to_key() Converst a data in buffer to KEY
 * int *dst_key_to_buffer() Writes out DST_KEY key matterial in buffer
 * void dst_free_key()          Releases all memory referenced by key structure
 */

#include "port_before.h"
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <memory.h>
#include <ctype.h>
#include <time.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>

#include "dst_internal.h"
#include "port_after.h"

/* static variables */
static int done_init = 0;
dst_func *dst_t_func[DST_MAX_ALGS];
const char *key_file_fmt_str = "Private-key-format: v%s\nAlgorithm: %d (%s)\n";
const char *dst_path = "";

/* internal I/O functions */
static DST_KEY *dst_s_read_public_key(const char *in_name,
                      const u_int16_t in_id, int in_alg);
static int dst_s_read_private_key_file(char *name, DST_KEY *pk_key,
                       u_int16_t in_id, int in_alg);
static int dst_s_write_public_key(const DST_KEY *key);
static int dst_s_write_private_key(const DST_KEY *key);

/* internal function to set up data structure */
static DST_KEY *dst_s_get_key_struct(const char *name, const int alg,
                     const int flags, const int protocol,
                     const int bits);

/*%
 *  dst_init
 *  This function initializes the Digital Signature Toolkit.
 *  Right now, it just checks the DSTKEYPATH environment variable.
 *  Parameters
 *  none
 *  Returns
 *  none
 */
void
dst_init()
{
    char *s;
    int len;

    if (done_init != 0)
        return;
    done_init = 1;

    s = getenv("DSTKEYPATH");
    len = 0;
    if (s) {
        struct stat statbuf;

        len = strlen(s);
        if (len > PATH_MAX) {
            EREPORT(("%s is longer than %d characters, ignoring\n",
                 s, PATH_MAX));
        } else if (stat(s, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode)) {
            EREPORT(("%s is not a valid directory\n", s));
        } else {
            char *tmp;
            tmp = (char *) malloc(len + 2);
            memcpy(tmp, s, len + 1);
            if (tmp[strlen(tmp) - 1] != '/') {
                tmp[strlen(tmp) + 1] = 0;
                tmp[strlen(tmp)] = '/';
            }
            dst_path = tmp;
        }
    }
    memset(dst_t_func, 0, sizeof(dst_t_func));
    /* first one is selected */
    dst_hmac_md5_init();
}

/*%
 *  dst_check_algorithm
 *  This function determines if the crypto system for the specified
 *  algorithm is present.
 *  Parameters
 *  alg     1       KEY_RSA
 *      3       KEY_DSA
 *        157     KEY_HMAC_MD5
 *            future algorithms TBD and registered with IANA.
 *  Returns
 *  1 - The algorithm is available.
 *  0 - The algorithm is not available.
 */
int
dst_check_algorithm(const int alg)
{
    return (dst_t_func[alg] != NULL);
}

/*%
 * dst_s_get_key_struct
 *  This function allocates key structure and fills in some of the
 *  fields of the structure.
 * Parameters:
 *  name:     the name of the key
 *  alg:      the algorithm number
 *  flags:    the dns flags of the key
 *  protocol: the dns protocol of the key
 *  bits:     the size of the key
 * Returns:
 *       NULL if error
 *       valid pointer otherwise
 */
static DST_KEY *
dst_s_get_key_struct(const char *name, const int alg, const int flags,
             const int protocol, const int bits)
{
    DST_KEY *new_key = NULL;

    if (dst_check_algorithm(alg)) /*%< make sure alg is available */
        new_key = (DST_KEY *) malloc(sizeof(*new_key));
    if (new_key == NULL)
        return (NULL);

    memset(new_key, 0, sizeof(*new_key));
    new_key->dk_key_name = strdup(name);
    if (new_key->dk_key_name == NULL) {
        free(new_key);
        return (NULL);
    }
    new_key->dk_alg = alg;
    new_key->dk_flags = flags;
    new_key->dk_proto = protocol;
    new_key->dk_KEY_struct = NULL;
    new_key->dk_key_size = bits;
    new_key->dk_func = dst_t_func[alg];
    return (new_key);
}

/*%
 *  dst_compare_keys
 *  Compares two keys for equality.
 *  Parameters
 *  key1, key2      Two keys to be compared.
 *  Returns
 *  0          The keys are equal.
 *  non-zero    The keys are not equal.
 */

int
dst_compare_keys(const DST_KEY *key1, const DST_KEY *key2)
{
    if (key1 == key2)
        return (0);
    if (key1 == NULL || key2 == NULL)
        return (4);
    if (key1->dk_alg != key2->dk_alg)
        return (1);
    if (key1->dk_key_size != key2->dk_key_size)
        return (2);
    if (key1->dk_id != key2->dk_id)
        return (3);
    return (key1->dk_func->compare(key1, key2));
}

/*%
 * dst_sign_data
 *  An incremental signing function.  Data is signed in steps.
 *  First the context must be initialized (SIG_MODE_INIT).
 *  Then data is hashed (SIG_MODE_UPDATE).  Finally the signature
 *  itself is created (SIG_MODE_FINAL).  This function can be called
 *  once with INIT, UPDATE and FINAL modes all set, or it can be
 *  called separately with a different mode set for each step.  The
 *  UPDATE step can be repeated.
 * Parameters
 *  mode    A bit mask used to specify operation(s) to be performed.
 *        SIG_MODE_INIT    1   Initialize digest
 *        SIG_MODE_UPDATE    2   Add data to digest
 *        SIG_MODE_FINAL      4   Generate signature
 *                        from signature
 *        SIG_MODE_ALL (SIG_MODE_INIT,SIG_MODE_UPDATE,SIG_MODE_FINAL
 *  data    Data to be signed.
 *  len     The length in bytes of data to be signed.
 *  in_key  Contains a private key to sign with.
 *        KEY structures should be handled (created, converted,
 *        compared, stored, freed) by the DST.
 *  signature
 *        The location to which the signature will be written.
 *  sig_len Length of the signature field in bytes.
 * Return
 *   0      Successfull INIT or Update operation
 *  &gt;0      success FINAL (sign) operation
 *  &lt;0      failure
 */

int
dst_sign_data(const int mode, DST_KEY *in_key, void **context,
          const u_char *data, const int len,
          u_char *signature, const int sig_len)
{
    DUMP(data, mode, len, "dst_sign_data()");

    if (mode & SIG_MODE_FINAL &&
        (in_key->dk_KEY_struct == NULL || signature == NULL))
        return (MISSING_KEY_OR_SIGNATURE);

    if (in_key->dk_func && in_key->dk_func->sign)
        return (in_key->dk_func->sign(mode, in_key, context, data, len,
                          signature, sig_len));
    return (UNKNOWN_KEYALG);
}

/*%
 *  dst_verify_data
 *  An incremental verify function.  Data is verified in steps.
 *  First the context must be initialized (SIG_MODE_INIT).
 *  Then data is hashed (SIG_MODE_UPDATE).  Finally the signature
 *  is verified (SIG_MODE_FINAL).  This function can be called
 *  once with INIT, UPDATE and FINAL modes all set, or it can be
 *  called separately with a different mode set for each step.  The
 *  UPDATE step can be repeated.
 *  Parameters
 *  mode    Operations to perform this time.
 *            SIG_MODE_INIT       1   Initialize digest
 *            SIG_MODE_UPDATE     2   add data to digest
 *            SIG_MODE_FINAL      4   verify signature
 *            SIG_MODE_ALL
 *            (SIG_MODE_INIT,SIG_MODE_UPDATE,SIG_MODE_FINAL)
 *  data    Data to pass through the hash function.
 *  len  Length of the data in bytes.
 *  in_key      Key for verification.
 *  signature   Location of signature.
 *  sig_len     Length of the signature in bytes.
 *  Returns
 *  0      Verify success
 *  Non-Zero    Verify Failure
 */

int
dst_verify_data(const int mode, DST_KEY *in_key, void **context,
        const u_char *data, const int len,
        const u_char *signature, const int sig_len)
{
    DUMP(data, mode, len, "dst_verify_data()");
    if (mode & SIG_MODE_FINAL &&
        (in_key->dk_KEY_struct == NULL || signature == NULL))
        return (MISSING_KEY_OR_SIGNATURE);

    if (in_key->dk_func == NULL || in_key->dk_func->verify == NULL)
        return (UNSUPPORTED_KEYALG);
    return (in_key->dk_func->verify(mode, in_key, context, data, len,
                    signature, sig_len));
}

/*%
 *  dst_read_private_key
 *  Access a private key.  First the list of private keys that have
 *  already been read in is searched, then the key accessed on disk.
 *  If the private key can be found, it is returned.  If the key cannot
 *  be found, a null pointer is returned.  The options specify required
 *  key characteristics.  If the private key requested does not have
 *  these characteristics, it will not be read.
 *  Parameters
 *  in_keyname  The private key name.
 *  in_id       The id of the private key.
 *  options     DST_FORCE_READ  Read from disk - don't use a previously
 *                    read key.
 *        DST_CAN_SIGN    The key must be useable for signing.
 *        DST_NO_AUTHEN   The key must be useable for authentication.
 *        DST_STANDARD    Return any key
 *  Returns
 *  NULL    If there is no key found in the current directory or
 *            this key has not been loaded before.
 *  !NULL       Success - KEY structure returned.
 */

DST_KEY *
dst_read_key(const char *in_keyname, const u_int16_t in_id,
         const int in_alg, const int type)
{
    char keyname[PATH_MAX];
    DST_KEY *dg_key = NULL, *pubkey = NULL;

    if (!dst_check_algorithm(in_alg)) { /*%< make sure alg is available */
        EREPORT(("dst_read_private_key(): Algorithm %d not suppored\n",
             in_alg));
        return (NULL);
    }
    if ((type & (DST_PUBLIC | DST_PRIVATE)) == 0)
        return (NULL);
    if (in_keyname == NULL) {
        EREPORT(("dst_read_private_key(): Null key name passed in\n"));
        return (NULL);
    } else if (strlen(in_keyname) >= sizeof(keyname)) {
        EREPORT(("dst_read_private_key(): keyname too big\n"));
        return (NULL);
    } else
        strcpy(keyname, in_keyname);

    /* before I read in the public key, check if it is allowed to sign */
    if ((pubkey = dst_s_read_public_key(keyname, in_id, in_alg)) == NULL)
        return (NULL);

    if (type == DST_PUBLIC)
        return pubkey;

    if (!(dg_key = dst_s_get_key_struct(keyname, pubkey->dk_alg,
                        pubkey->dk_flags, pubkey->dk_proto,
                        0)))
        return (dg_key);
    /* Fill in private key and some fields in the general key structure */
    if (dst_s_read_private_key_file(keyname, dg_key, pubkey->dk_id,
                    pubkey->dk_alg) == 0)
        dg_key = dst_free_key(dg_key);

    (void)dst_free_key(pubkey);
    return (dg_key);
}

int
dst_write_key(const DST_KEY *key, const int type)
{
    int pub = 0, priv = 0;

    if (key == NULL)
        return (0);
    if (!dst_check_algorithm(key->dk_alg)) { /*%< make sure alg is available */
        EREPORT(("dst_write_key(): Algorithm %d not suppored\n",
             key->dk_alg));
        return (UNSUPPORTED_KEYALG);
    }
    if ((type & (DST_PRIVATE|DST_PUBLIC)) == 0)
        return (0);

    if (type & DST_PUBLIC)
        if ((pub = dst_s_write_public_key(key)) < 0)
            return (pub);
    if (type & DST_PRIVATE)
        if ((priv = dst_s_write_private_key(key)) < 0)
            return (priv);
    return (priv+pub);
}

/*%
 *  dst_write_private_key
 *  Write a private key to disk.  The filename will be of the form:
 *  K&lt;key-&gt;dk_name&gt;+&lt;key-&gt;dk_alg+&gt;&lt;key-d&gt;k_id.&gt;&lt;private key suffix&gt;.
 *  If there is already a file with this name, an error is returned.
 *
 *  Parameters
 *  key     A DST managed key structure that contains
 *        all information needed about a key.
 *  Return
 *  &gt;= 0    Correct behavior.  Returns length of encoded key value
 *        written to disk.
 *  &lt;  0    error.
 */

static int
dst_s_write_private_key(const DST_KEY *key)
{
    u_char encoded_block[RAW_KEY_SIZE];
    char file[PATH_MAX];
    int len;
    FILE *fp;

    /* First encode the key into the portable key format */
    if (key == NULL)
        return (-1);
    if (key->dk_KEY_struct == NULL)
        return (0); /*%< null key has no private key */
    if (key->dk_func == NULL || key->dk_func->to_file_fmt == NULL) {
        EREPORT(("dst_write_private_key(): Unsupported operation %d\n",
             key->dk_alg));
        return (-5);
    } else if ((len = key->dk_func->to_file_fmt(key, (char *)encoded_block,
                         sizeof(encoded_block))) <= 0) {
        EREPORT(("dst_write_private_key(): Failed encoding private RSA bsafe key %d\n", len));
        return (-8);
    }
    /* Now I can create the file I want to use */
    dst_s_build_filename(file, key->dk_key_name, key->dk_id, key->dk_alg,
                 PRIVATE_KEY, PATH_MAX);

    /* Do not overwrite an existing file */
    if ((fp = dst_s_fopen(file, "w", 0600)) != NULL) {
        int nn;
        if ((nn = fwrite(encoded_block, 1, len, fp)) != len) {
            EREPORT(("dst_write_private_key(): Write failure on %s %d != %d errno=%d\n",
                 file, len, nn, errno));
            fclose(fp);
            return (-5);
        }
        fclose(fp);
    } else {
        EREPORT(("dst_write_private_key(): Can not create file %s\n"
             ,file));
        return (-6);
    }
    memset(encoded_block, 0, len);
    return (len);
}

/*%
*
 *  dst_read_public_key
 *  Read a public key from disk and store in a DST key structure.
 *  Parameters
 *  in_name  K&lt;in_name&gt;&lt;in_id&gt;.&lt;public key suffix&gt; is the
 *            filename of the key file to be read.
 *  Returns
 *  NULL        If the key does not exist or no name is supplied.
 *  NON-NULL    Initialized key structure if the key exists.
 */

static DST_KEY *
dst_s_read_public_key(const char *in_name, const u_int16_t in_id, int in_alg)
{
    int flags, proto, alg, len, dlen;
    int c;
    char name[PATH_MAX], enckey[RAW_KEY_SIZE], *notspace;
    u_char deckey[RAW_KEY_SIZE];
    FILE *fp;

    if (in_name == NULL) {
        EREPORT(("dst_read_public_key(): No key name given\n"));
        return (NULL);
    }
    if (dst_s_build_filename(name, in_name, in_id, in_alg, PUBLIC_KEY,
                 PATH_MAX) == -1) {
        EREPORT(("dst_read_public_key(): Cannot make filename from %s, %d, and %s\n",
             in_name, in_id, PUBLIC_KEY));
        return (NULL);
    }
    /*
     * Open the file and read it's formatted contents up to key
     * File format:
     *    domain.name [ttl] [IN] KEY  &lt;flags&gt; &lt;protocol&gt; &lt;algorithm&gt; &lt;key&gt;
     * flags, proto, alg stored as decimal (or hex numbers FIXME).
     * (FIXME: handle parentheses for line continuation.)
     */
    if ((fp = dst_s_fopen(name, "r", 0)) == NULL) {
        EREPORT(("dst_read_public_key(): Public Key not found %s\n",
             name));
        return (NULL);
    }
    /* Skip domain name, which ends at first blank */
    while ((c = getc(fp)) != EOF)
        if (isspace(c))
            break;
    /* Skip blank to get to next field */
    while ((c = getc(fp)) != EOF)
        if (!isspace(c))
            break;

    /* Skip optional TTL -- if initial digit, skip whole word. */
    if (isdigit(c)) {
        while ((c = getc(fp)) != EOF)
            if (isspace(c))
                break;
        while ((c = getc(fp)) != EOF)
            if (!isspace(c))
                break;
    }
    /* Skip optional "IN" */
    if (c == 'I' || c == 'i') {
        while ((c = getc(fp)) != EOF)
            if (isspace(c))
                break;
        while ((c = getc(fp)) != EOF)
            if (!isspace(c))
                break;
    }
    /* Locate and skip "KEY" */
    if (c != 'K' && c != 'k') {
        EREPORT(("\"KEY\" doesn't appear in file: %s", name));
        return NULL;
    }
    while ((c = getc(fp)) != EOF)
        if (isspace(c))
            break;
    while ((c = getc(fp)) != EOF)
        if (!isspace(c))
            break;
    ungetc(c, fp);      /*%< return the charcter to the input field */
    /* Handle hex!! FIXME.  */

    if (fscanf(fp, "%d %d %d", &flags, &proto, &alg) != 3) {
        EREPORT(("dst_read_public_key(): Can not read flag/proto/alg field from %s\n"
             ,name));
        return (NULL);
    }
    /* read in the key string */
    fgets(enckey, sizeof(enckey), fp);

    /* If we aren't at end-of-file, something is wrong.  */
    while ((c = getc(fp)) != EOF)
        if (!isspace(c))
            break;
    if (!feof(fp)) {
        EREPORT(("Key too long in file: %s", name));
        return NULL;
    }
    fclose(fp);

    if ((len = strlen(enckey)) <= 0)
        return (NULL);

    /* discard \n */
    enckey[--len] = '\0';

    /* remove leading spaces */
    for (notspace = (char *) enckey; isspace((*notspace)&0xff); len--)
        notspace++;

    dlen = b64_pton(notspace, deckey, sizeof(deckey));
    if (dlen < 0) {
        EREPORT(("dst_read_public_key: bad return from b64_pton = %d",
             dlen));
        return (NULL);
    }
    /* store key and info in a key structure that is returned */
/*  return dst_store_public_key(in_name, alg, proto, 666, flags, deckey,
                    dlen);*/
    return dst_buffer_to_key(in_name, alg, flags, proto, deckey, dlen);
}

/*%
 *  dst_write_public_key
 *  Write a key to disk in DNS format.
 *  Parameters
 *  key     Pointer to a DST key structure.
 *  Returns
 *  0       Failure
 *  1       Success
 */

static int
dst_s_write_public_key(const DST_KEY *key)
{
    FILE *fp;
    char filename[PATH_MAX];
    u_char out_key[RAW_KEY_SIZE];
    char enc_key[RAW_KEY_SIZE];
    int len = 0;
    int mode;

    memset(out_key, 0, sizeof(out_key));
    if (key == NULL) {
        EREPORT(("dst_write_public_key(): No key specified \n"));
        return (0);
    } else if ((len = dst_key_to_dnskey(key, out_key, sizeof(out_key)))< 0)
        return (0);

    /* Make the filename */
    if (dst_s_build_filename(filename, key->dk_key_name, key->dk_id,
                 key->dk_alg, PUBLIC_KEY, PATH_MAX) == -1) {
        EREPORT(("dst_write_public_key(): Cannot make filename from %s, %d, and %s\n",
             key->dk_key_name, key->dk_id, PUBLIC_KEY));
        return (0);
    }
    /* XXX in general this should be a check for symmetric keys */
    mode = (key->dk_alg == KEY_HMAC_MD5) ? 0600 : 0644;
    /* create public key file */
    if ((fp = dst_s_fopen(filename, "w+", mode)) == NULL) {
        EREPORT(("DST_write_public_key: open of file:%s failed (errno=%d)\n",
             filename, errno));
        return (0);
    }
    /*write out key first base64 the key data */
    if (key->dk_flags & DST_EXTEND_FLAG)
        b64_ntop(&out_key[6], len - 6, enc_key, sizeof(enc_key));
    else
        b64_ntop(&out_key[4], len - 4, enc_key, sizeof(enc_key));
    fprintf(fp, "%s IN KEY %d %d %d %s\n",
        key->dk_key_name,
        key->dk_flags, key->dk_proto, key->dk_alg, enc_key);
    fclose(fp);
    return (1);
}

/*%
 *  dst_dnskey_to_public_key
 *  This function converts the contents of a DNS KEY RR into a DST
 *  key structure.
 *  Paramters
 *  len  Length of the RDATA of the KEY RR RDATA
 *  rdata    A pointer to the the KEY RR RDATA.
 *  in_name     Key name to be stored in key structure.
 *  Returns
 *  NULL        Failure
 *  NON-NULL    Success.  Pointer to key structure.
 *          Caller's responsibility to free() it.
 */

DST_KEY *
dst_dnskey_to_key(const char *in_name, const u_char *rdata, const int len)
{
    DST_KEY *key_st;
    int alg ;
    int start = DST_KEY_START;

    if (rdata == NULL || len <= DST_KEY_ALG) /*%< no data */
        return (NULL);
    alg = (u_int8_t) rdata[DST_KEY_ALG];
    if (!dst_check_algorithm(alg)) { /*%< make sure alg is available */
        EREPORT(("dst_dnskey_to_key(): Algorithm %d not suppored\n",
             alg));
        return (NULL);
    }

    if (in_name == NULL)
        return (NULL);

    if ((key_st = dst_s_get_key_struct(in_name, alg, 0, 0, 0)) == NULL)
        return (NULL);

    key_st->dk_id = dst_s_dns_key_id(rdata, len);
    key_st->dk_flags = dst_s_get_int16(rdata);
    key_st->dk_proto = (u_int16_t) rdata[DST_KEY_PROT];
    if (key_st->dk_flags & DST_EXTEND_FLAG) {
        u_int32_t ext_flags;
        ext_flags = (u_int32_t) dst_s_get_int16(&rdata[DST_EXT_FLAG]);
        key_st->dk_flags = key_st->dk_flags | (ext_flags << 16);
        start += 2;
    }
    /*
     * now point to the begining of the data representing the encoding
     * of the key
     */
    if (key_st->dk_func && key_st->dk_func->from_dns_key) {
        if (key_st->dk_func->from_dns_key(key_st, &rdata[start],
                          len - start) > 0)
            return (key_st);
    } else
        EREPORT(("dst_dnskey_to_public_key(): unsuppored alg %d\n",
             alg));

    SAFE_FREE(key_st);
    return (key_st);
}

/*%
 *  dst_public_key_to_dnskey
 *  Function to encode a public key into DNS KEY wire format
 *  Parameters
 *  key      Key structure to encode.
 *  out_storage     Location to write the encoded key to.
 *  out_len  Size of the output array.
 *  Returns
 *  <0      Failure
 *  >=0     Number of bytes written to out_storage
 */

int
dst_key_to_dnskey(const DST_KEY *key, u_char *out_storage,
             const int out_len)
{
    u_int16_t val;
    int loc = 0;
    int enc_len = 0;
    if (key == NULL)
        return (-1);

    if (!dst_check_algorithm(key->dk_alg)) { /*%< make sure alg is available */
        EREPORT(("dst_key_to_dnskey(): Algorithm %d not suppored\n",
             key->dk_alg));
        return (UNSUPPORTED_KEYALG);
    }
    memset(out_storage, 0, out_len);
    val = (u_int16_t)(key->dk_flags & 0xffff);
    dst_s_put_int16(out_storage, val);
    loc += 2;

    out_storage[loc++] = (u_char) key->dk_proto;
    out_storage[loc++] = (u_char) key->dk_alg;

    if (key->dk_flags > 0xffff) {   /*%< Extended flags */
        val = (u_int16_t)((key->dk_flags >> 16) & 0xffff);
        dst_s_put_int16(&out_storage[loc], val);
        loc += 2;
    }
    if (key->dk_KEY_struct == NULL)
        return (loc);
    if (key->dk_func && key->dk_func->to_dns_key) {
        enc_len = key->dk_func->to_dns_key(key,
                         (u_char *) &out_storage[loc],
                           out_len - loc);
        if (enc_len > 0)
            return (enc_len + loc);
        else
            return (-1);
    } else
        EREPORT(("dst_key_to_dnskey(): Unsupported ALG %d\n",
             key->dk_alg));
    return (-1);
}

/*%
 *  dst_buffer_to_key
 *  Function to encode a string of raw data into a DST key
 *  Parameters
 *  alg     The algorithm (HMAC only)
 *  key     A pointer to the data
 *  keylen      The length of the data
 *  Returns
 *  NULL        an error occurred
 *  NON-NULL    the DST key
 */
DST_KEY *
dst_buffer_to_key(const char *key_name,     /*!< name of the key  */
          const int alg,        /*!< algorithm  */
          const int flags,      /*!< dns flags  */
          const int protocol,       /*!< dns protocol  */
          const u_char *key_buf,    /*!< key in dns wire fmt  */
          const int key_len)        /*!< size of key  */
{

    DST_KEY *dkey = NULL;
    int dnslen;
    u_char dns[2048];

    if (!dst_check_algorithm(alg)) { /*%< make sure alg is available */
        EREPORT(("dst_buffer_to_key(): Algorithm %d not suppored\n", alg));
        return (NULL);
    }

    dkey = dst_s_get_key_struct(key_name, alg, flags, protocol, -1);

    if (dkey == NULL || dkey->dk_func == NULL ||
        dkey->dk_func->from_dns_key == NULL)
        return (dst_free_key(dkey));

    if (dkey->dk_func->from_dns_key(dkey, key_buf, key_len) < 0) {
        EREPORT(("dst_buffer_to_key(): dst_buffer_to_hmac failed\n"));
        return (dst_free_key(dkey));
    }

    dnslen = dst_key_to_dnskey(dkey, dns, sizeof(dns));
    dkey->dk_id = dst_s_dns_key_id(dns, dnslen);
    return (dkey);
}

int
dst_key_to_buffer(DST_KEY *key, u_char *out_buff, int buf_len)
{
    int len;
  /* this function will extrac the secret of HMAC into a buffer */
    if (key == NULL)
        return (0);
    if (key->dk_func != NULL && key->dk_func->to_dns_key != NULL) {
        len = key->dk_func->to_dns_key(key, out_buff, buf_len);
        if (len < 0)
            return (0);
        return (len);
    }
    return (0);
}

/*%
 * dst_s_read_private_key_file
 *     Function reads in private key from a file.
 *     Fills out the KEY structure.
 * Parameters
 *     name    Name of the key to be read.
 *     pk_key  Structure that the key is returned in.
 *     in_id   Key identifier (tag)
 * Return
 *     1 if everthing works
 *     0 if there is any problem
 */

static int
dst_s_read_private_key_file(char *name, DST_KEY *pk_key, u_int16_t in_id,
                int in_alg)
{
    int cnt, alg, len, major, minor, file_major, file_minor;
    int ret, id;
    char filename[PATH_MAX];
    u_char in_buff[RAW_KEY_SIZE], *p;
    FILE *fp;
    int dnslen;
    u_char dns[2048];

    if (name == NULL || pk_key == NULL) {
        EREPORT(("dst_read_private_key_file(): No key name given\n"));
        return (0);
    }
    /* Make the filename */
    if (dst_s_build_filename(filename, name, in_id, in_alg, PRIVATE_KEY,
                 PATH_MAX) == -1) {
        EREPORT(("dst_read_private_key(): Cannot make filename from %s, %d, and %s\n",
             name, in_id, PRIVATE_KEY));
        return (0);
    }
    /* first check if we can find the key file */
    if ((fp = dst_s_fopen(filename, "r", 0)) == NULL) {
        EREPORT(("dst_s_read_private_key_file: Could not open file %s in directory %s\n",
             filename, dst_path[0] ? dst_path :
             (char *) getcwd(NULL, PATH_MAX - 1)));
        return (0);
    }
    /* now read the header info from the file */
    if ((cnt = fread(in_buff, 1, sizeof(in_buff), fp)) < 5) {
        fclose(fp);
        EREPORT(("dst_s_read_private_key_file: error reading file %s (empty file)\n",
             filename));
        return (0);
    }
    /* decrypt key */
    fclose(fp);
    if (memcmp(in_buff, "Private-key-format: v", 20) != 0)
        goto fail;
    len = cnt;
    p = in_buff;

    if (!dst_s_verify_str((const char **) (void *)&p,
                   "Private-key-format: v")) {
        EREPORT(("dst_s_read_private_key_file(): Not a Key file/Decrypt failed %s\n", name));
        goto fail;
    }
    /* read in file format */
    sscanf((char *)p, "%d.%d", &file_major, &file_minor);
    sscanf(KEY_FILE_FORMAT, "%d.%d", &major, &minor);
    if (file_major < 1) {
        EREPORT(("dst_s_read_private_key_file(): Unknown keyfile %d.%d version for %s\n",
             file_major, file_minor, name));
        goto fail;
    } else if (file_major > major || file_minor > minor)
        EREPORT((
                "dst_s_read_private_key_file(): Keyfile %s version higher than mine %d.%d MAY FAIL\n",
                name, file_major, file_minor));

    while (*p++ != '\n') ;  /*%< skip to end of line */

    if (!dst_s_verify_str((const char **) (void *)&p, "Algorithm: "))
        goto fail;

    if (sscanf((char *)p, "%d", &alg) != 1)
        goto fail;
    while (*p++ != '\n') ;  /*%< skip to end of line */

    if (pk_key->dk_key_name && !strcmp(pk_key->dk_key_name, name))
        SAFE_FREE2(pk_key->dk_key_name, strlen(pk_key->dk_key_name));
    pk_key->dk_key_name = (char *) strdup(name);

    /* allocate and fill in key structure */
    if (pk_key->dk_func == NULL || pk_key->dk_func->from_file_fmt == NULL)
        goto fail;

    ret = pk_key->dk_func->from_file_fmt(pk_key, (char *)p, &in_buff[len] - p);
    if (ret < 0)
        goto fail;

    dnslen = dst_key_to_dnskey(pk_key, dns, sizeof(dns));
    id = dst_s_dns_key_id(dns, dnslen);

    /* Make sure the actual key tag matches the input tag used in the filename
     */
    if (id != in_id) {
        EREPORT(("dst_s_read_private_key_file(): actual tag of key read %d != input tag used to build filename %d.\n", id, in_id));
        goto fail;
    }
    pk_key->dk_id = (u_int16_t) id;
    pk_key->dk_alg = alg;
    memset(in_buff, 0, cnt);
    return (1);

 fail:
    memset(in_buff, 0, cnt);
    return (0);
}

/*%
 *  Generate and store a public/private keypair.
 *  Keys will be stored in formatted files.
 *
 *  Parameters
 &
 *\par  name    Name of the new key.  Used to create key files
 *\li         K&lt;name&gt;+&lt;alg&gt;+&lt;id&gt;.public and K&lt;name&gt;+&lt;alg&gt;+&lt;id&gt;.private.
 *\par  bits    Size of the new key in bits.
 *\par  exp     What exponent to use:
 *\li         0    use exponent 3
 *\li         non-zero    use Fermant4
 *\par  flags   The default value of the DNS Key flags.
 *\li         The DNS Key RR Flag field is defined in RFC2065,
 *        section 3.3.  The field has 16 bits.
 *\par  protocol
 *\li         Default value of the DNS Key protocol field.
 *\li         The DNS Key protocol field is defined in RFC2065,
 *        section 3.4.  The field has 8 bits.
 *\par  alg     What algorithm to use.  Currently defined:
 *\li         KEY_RSA       1
 *\li         KEY_DSA       3
 *\li         KEY_HMAC    157
 *\par  out_id The key tag is returned.
 *
 *  Return
 *\li   NULL        Failure
 *\li   non-NULL    the generated key pair
 *          Caller frees the result, and its dk_name pointer.
 */
DST_KEY *
dst_generate_key(const char *name, const int bits, const int exp,
         const int flags, const int protocol, const int alg)
{
    DST_KEY *new_key = NULL;
    int dnslen;
    u_char dns[2048];

    if (name == NULL)
        return (NULL);

    if (!dst_check_algorithm(alg)) { /*%< make sure alg is available */
        EREPORT(("dst_generate_key(): Algorithm %d not suppored\n", alg));
        return (NULL);
    }

    new_key = dst_s_get_key_struct(name, alg, flags, protocol, bits);
    if (new_key == NULL)
        return (NULL);
    if (bits == 0) /*%< null key we are done */
        return (new_key);
    if (new_key->dk_func == NULL || new_key->dk_func->generate == NULL) {
        EREPORT(("dst_generate_key_pair():Unsupported algorithm %d\n",
             alg));
        return (dst_free_key(new_key));
    }
    if (new_key->dk_func->generate(new_key, exp) <= 0) {
        EREPORT(("dst_generate_key_pair(): Key generation failure %s %d %d %d\n",
             new_key->dk_key_name, new_key->dk_alg,
             new_key->dk_key_size, exp));
        return (dst_free_key(new_key));
    }

    dnslen = dst_key_to_dnskey(new_key, dns, sizeof(dns));
    if (dnslen != UNSUPPORTED_KEYALG)
        new_key->dk_id = dst_s_dns_key_id(dns, dnslen);
    else
        new_key->dk_id = 0;

    return (new_key);
}

/*%
 *  Release all data structures pointed to by a key structure.
 *
 *  Parameters
 *\li   f_key   Key structure to be freed.
 */

DST_KEY *
dst_free_key(DST_KEY *f_key)
{

    if (f_key == NULL)
        return (f_key);
    if (f_key->dk_func && f_key->dk_func->destroy)
        f_key->dk_KEY_struct =
            f_key->dk_func->destroy(f_key->dk_KEY_struct);
    else {
        EREPORT(("dst_free_key(): Unknown key alg %d\n",
             f_key->dk_alg));
    }
    if (f_key->dk_KEY_struct) {
        free(f_key->dk_KEY_struct);
        f_key->dk_KEY_struct = NULL;
    }
    if (f_key->dk_key_name)
        SAFE_FREE(f_key->dk_key_name);
    SAFE_FREE(f_key);
    return (NULL);
}

/*%
 *  Return the maximim size of signature from the key specified in bytes
 *
 * Parameters
 *\li      key
 *
 * Returns
 *  \li   bytes
 */
int
dst_sig_size(DST_KEY *key) {
    switch (key->dk_alg) {
        case KEY_HMAC_MD5:
        return (16);
        case KEY_HMAC_SHA1:
        return (20);
        case KEY_RSA:
        return (key->dk_key_size + 7) / 8;
        case KEY_DSA:
        return (40);
        default:
        EREPORT(("dst_sig_size(): Unknown key alg %d\n", key->dk_alg));
        return -1;
    }
}

/*! \file */