pgp-pgsql.c

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/*
 * pgp-pgsql.c
 *      PostgreSQL wrappers for pgp.
 *
 * Copyright (c) 2005 Marko Kreen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * contrib/pgcrypto/pgp-pgsql.c
 */

#include "postgres.h"

#include "lib/stringinfo.h"
#include "catalog/pg_type.h"
#include "mb/pg_wchar.h"
#include "utils/builtins.h"
#include "utils/array.h"
#include "funcapi.h"

#include "mbuf.h"
#include "px.h"
#include "pgp.h"

/*
 * public functions
 */
PG_FUNCTION_INFO_V1(pgp_sym_encrypt_bytea);
PG_FUNCTION_INFO_V1(pgp_sym_encrypt_text);
PG_FUNCTION_INFO_V1(pgp_sym_decrypt_bytea);
PG_FUNCTION_INFO_V1(pgp_sym_decrypt_text);

PG_FUNCTION_INFO_V1(pgp_pub_encrypt_bytea);
PG_FUNCTION_INFO_V1(pgp_pub_encrypt_text);
PG_FUNCTION_INFO_V1(pgp_pub_decrypt_bytea);
PG_FUNCTION_INFO_V1(pgp_pub_decrypt_text);

PG_FUNCTION_INFO_V1(pgp_key_id_w);

PG_FUNCTION_INFO_V1(pg_armor);
PG_FUNCTION_INFO_V1(pg_dearmor);
PG_FUNCTION_INFO_V1(pgp_armor_headers);

/*
 * Mix a block of data into RNG.
 */
static void
add_block_entropy(PX_MD *md, text *data)
{
    uint8       sha1[20];

    px_md_reset(md);
    px_md_update(md, (uint8 *) VARDATA(data), VARSIZE(data) - VARHDRSZ);
    px_md_finish(md, sha1);

    px_add_entropy(sha1, 20);

    px_memset(sha1, 0, 20);
}

/*
 * Mix user data into RNG.  It is for user own interests to have
 * RNG state shuffled.
 */
static void
add_entropy(text *data1, text *data2, text *data3)
{
    PX_MD      *md;
    uint8       rnd[3];

    if (!data1 && !data2 && !data3)
        return;

    if (px_get_random_bytes(rnd, 3) < 0)
        return;

    if (px_find_digest("sha1", &md) < 0)
        return;

    /*
     * Try to make the feeding unpredictable.
     *
     * Prefer data over keys, as it's rather likely that key is same in
     * several calls.
     */

    /* chance: 7/8 */
    if (data1 && rnd[0] >= 32)
        add_block_entropy(md, data1);

    /* chance: 5/8 */
    if (data2 && rnd[1] >= 160)
        add_block_entropy(md, data2);

    /* chance: 5/8 */
    if (data3 && rnd[2] >= 160)
        add_block_entropy(md, data3);

    px_md_free(md);
    px_memset(rnd, 0, sizeof(rnd));
}

/*
 * returns src in case of no conversion or error
 */
static text *
convert_charset(text *src, int cset_from, int cset_to)
{
    int         src_len = VARSIZE(src) - VARHDRSZ;
    unsigned char *dst;
    unsigned char *csrc = (unsigned char *) VARDATA(src);
    text       *res;

    dst = pg_do_encoding_conversion(csrc, src_len, cset_from, cset_to);
    if (dst == csrc)
        return src;

    res = cstring_to_text((char *) dst);
    pfree(dst);
    return res;
}

static text *
convert_from_utf8(text *src)
{
    return convert_charset(src, PG_UTF8, GetDatabaseEncoding());
}

static text *
convert_to_utf8(text *src)
{
    return convert_charset(src, GetDatabaseEncoding(), PG_UTF8);
}

static bool
string_is_ascii(const char *str)
{
    const char *p;

    for (p = str; *p; p++)
    {
        if (IS_HIGHBIT_SET(*p))
            return false;
    }
    return true;
}

static void
clear_and_pfree(text *p)
{
    px_memset(p, 0, VARSIZE(p));
    pfree(p);
}

/*
 * expect-* arguments storage
 */
struct debug_expect
{
    int         debug;
    int         expect;
    int         cipher_algo;
    int         s2k_mode;
    int         s2k_count;
    int         s2k_cipher_algo;
    int         s2k_digest_algo;
    int         compress_algo;
    int         use_sess_key;
    int         disable_mdc;
    int         unicode_mode;
};

static void
fill_expect(struct debug_expect * ex, int text_mode)
{
    ex->debug = 0;
    ex->expect = 0;
    ex->cipher_algo = -1;
    ex->s2k_mode = -1;
    ex->s2k_count = -1;
    ex->s2k_cipher_algo = -1;
    ex->s2k_digest_algo = -1;
    ex->compress_algo = -1;
    ex->use_sess_key = -1;
    ex->disable_mdc = -1;
    ex->unicode_mode = -1;
}

#define EX_MSG(arg) \
    ereport(NOTICE, (errmsg( \
        "pgp_decrypt: unexpected %s: expected %d got %d", \
        CppAsString(arg), ex->arg, ctx->arg)))

#define EX_CHECK(arg) do { \
        if (ex->arg >= 0 && ex->arg != ctx->arg) EX_MSG(arg); \
    } while (0)

static void
check_expect(PGP_Context *ctx, struct debug_expect * ex)
{
    EX_CHECK(cipher_algo);
    EX_CHECK(s2k_mode);
    EX_CHECK(s2k_count);
    EX_CHECK(s2k_digest_algo);
    EX_CHECK(use_sess_key);
    if (ctx->use_sess_key)
        EX_CHECK(s2k_cipher_algo);
    EX_CHECK(disable_mdc);
    EX_CHECK(compress_algo);
    EX_CHECK(unicode_mode);
}

static void
show_debug(const char *msg)
{
    ereport(NOTICE, (errmsg("dbg: %s", msg)));
}

static int
set_arg(PGP_Context *ctx, char *key, char *val,
        struct debug_expect * ex)
{
    int         res = 0;

    if (strcmp(key, "cipher-algo") == 0)
        res = pgp_set_cipher_algo(ctx, val);
    else if (strcmp(key, "disable-mdc") == 0)
        res = pgp_disable_mdc(ctx, atoi(val));
    else if (strcmp(key, "sess-key") == 0)
        res = pgp_set_sess_key(ctx, atoi(val));
    else if (strcmp(key, "s2k-mode") == 0)
        res = pgp_set_s2k_mode(ctx, atoi(val));
    else if (strcmp(key, "s2k-count") == 0)
        res = pgp_set_s2k_count(ctx, atoi(val));
    else if (strcmp(key, "s2k-digest-algo") == 0)
        res = pgp_set_s2k_digest_algo(ctx, val);
    else if (strcmp(key, "s2k-cipher-algo") == 0)
        res = pgp_set_s2k_cipher_algo(ctx, val);
    else if (strcmp(key, "compress-algo") == 0)
        res = pgp_set_compress_algo(ctx, atoi(val));
    else if (strcmp(key, "compress-level") == 0)
        res = pgp_set_compress_level(ctx, atoi(val));
    else if (strcmp(key, "convert-crlf") == 0)
        res = pgp_set_convert_crlf(ctx, atoi(val));
    else if (strcmp(key, "unicode-mode") == 0)
        res = pgp_set_unicode_mode(ctx, atoi(val));

    /*
     * The remaining options are for debugging/testing and are therefore not
     * documented in the user-facing docs.
     */
    else if (ex != NULL && strcmp(key, "debug") == 0)
        ex->debug = atoi(val);
    else if (ex != NULL && strcmp(key, "expect-cipher-algo") == 0)
    {
        ex->expect = 1;
        ex->cipher_algo = pgp_get_cipher_code(val);
    }
    else if (ex != NULL && strcmp(key, "expect-disable-mdc") == 0)
    {
        ex->expect = 1;
        ex->disable_mdc = atoi(val);
    }
    else if (ex != NULL && strcmp(key, "expect-sess-key") == 0)
    {
        ex->expect = 1;
        ex->use_sess_key = atoi(val);
    }
    else if (ex != NULL && strcmp(key, "expect-s2k-mode") == 0)
    {
        ex->expect = 1;
        ex->s2k_mode = atoi(val);
    }
    else if (ex != NULL && strcmp(key, "expect-s2k-count") == 0)
    {
        ex->expect = 1;
        ex->s2k_count = atoi(val);
    }
    else if (ex != NULL && strcmp(key, "expect-s2k-digest-algo") == 0)
    {
        ex->expect = 1;
        ex->s2k_digest_algo = pgp_get_digest_code(val);
    }
    else if (ex != NULL && strcmp(key, "expect-s2k-cipher-algo") == 0)
    {
        ex->expect = 1;
        ex->s2k_cipher_algo = pgp_get_cipher_code(val);
    }
    else if (ex != NULL && strcmp(key, "expect-compress-algo") == 0)
    {
        ex->expect = 1;
        ex->compress_algo = atoi(val);
    }
    else if (ex != NULL && strcmp(key, "expect-unicode-mode") == 0)
    {
        ex->expect = 1;
        ex->unicode_mode = atoi(val);
    }
    else
        res = PXE_ARGUMENT_ERROR;

    return res;
}

/*
 * Find next word.  Handle ',' and '=' as words.  Skip whitespace.
 * Put word info into res_p, res_len.
 * Returns ptr to next word.
 */
static char *
getword(char *p, char **res_p, int *res_len)
{
    /* whitespace at start */
    while (*p && (*p == ' ' || *p == '\t' || *p == '\n'))
        p++;

    /* word data */
    *res_p = p;
    if (*p == '=' || *p == ',')
        p++;
    else
        while (*p && !(*p == ' ' || *p == '\t' || *p == '\n'
                       || *p == '=' || *p == ','))
            p++;

    /* word end */
    *res_len = p - *res_p;

    /* whitespace at end */
    while (*p && (*p == ' ' || *p == '\t' || *p == '\n'))
        p++;

    return p;
}

/*
 * Convert to lowercase asciiz string.
 */
static char *
downcase_convert(const uint8 *s, int len)
{
    int         c,
                i;
    char       *res = palloc(len + 1);

    for (i = 0; i < len; i++)
    {
        c = s[i];
        if (c >= 'A' && c <= 'Z')
            c += 'a' - 'A';
        res[i] = c;
    }
    res[len] = 0;
    return res;
}

static int
parse_args(PGP_Context *ctx, uint8 *args, int arg_len,
           struct debug_expect * ex)
{
    char       *str = downcase_convert(args, arg_len);
    char       *key,
               *val;
    int         key_len,
                val_len;
    int         res = 0;
    char       *p = str;

    while (*p)
    {
        res = PXE_ARGUMENT_ERROR;
        p = getword(p, &key, &key_len);
        if (*p++ != '=')
            break;
        p = getword(p, &val, &val_len);
        if (*p == '\0')
            ;
        else if (*p++ != ',')
            break;

        if (*key == 0 || *val == 0 || val_len == 0)
            break;

        key[key_len] = 0;
        val[val_len] = 0;

        res = set_arg(ctx, key, val, ex);
        if (res < 0)
            break;
    }
    pfree(str);
    return res;
}

static MBuf *
create_mbuf_from_vardata(text *data)
{
    return mbuf_create_from_data((uint8 *) VARDATA(data),
                                 VARSIZE(data) - VARHDRSZ);
}

static void
init_work(PGP_Context **ctx_p, int is_text,
          text *args, struct debug_expect * ex)
{
    int         err = pgp_init(ctx_p);

    fill_expect(ex, is_text);

    if (err == 0 && args != NULL)
        err = parse_args(*ctx_p, (uint8 *) VARDATA(args),
                         VARSIZE(args) - VARHDRSZ, ex);

    if (err)
    {
        ereport(ERROR,
                (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
                 errmsg("%s", px_strerror(err))));
    }

    if (ex->debug)
        px_set_debug_handler(show_debug);

    pgp_set_text_mode(*ctx_p, is_text);
}

static bytea *
encrypt_internal(int is_pubenc, int is_text,
                 text *data, text *key, text *args)
{
    MBuf       *src,
               *dst;
    uint8       tmp[VARHDRSZ];
    uint8      *restmp;
    bytea      *res;
    int         res_len;
    PGP_Context *ctx;
    int         err;
    struct debug_expect ex;
    text       *tmp_data = NULL;

    /*
     * Add data and key info RNG.
     */
    add_entropy(data, key, NULL);

    init_work(&ctx, is_text, args, &ex);

    if (is_text && pgp_get_unicode_mode(ctx))
    {
        tmp_data = convert_to_utf8(data);
        if (tmp_data == data)
            tmp_data = NULL;
        else
            data = tmp_data;
    }

    src = create_mbuf_from_vardata(data);
    dst = mbuf_create(VARSIZE(data) + 128);

    /*
     * reserve room for header
     */
    mbuf_append(dst, tmp, VARHDRSZ);

    /*
     * set key
     */
    if (is_pubenc)
    {
        MBuf       *kbuf = create_mbuf_from_vardata(key);

        err = pgp_set_pubkey(ctx, kbuf,
                             NULL, 0, 0);
        mbuf_free(kbuf);
    }
    else
        err = pgp_set_symkey(ctx, (uint8 *) VARDATA(key),
                             VARSIZE(key) - VARHDRSZ);

    /*
     * encrypt
     */
    if (err >= 0)
        err = pgp_encrypt(ctx, src, dst);

    /*
     * check for error
     */
    if (err)
    {
        if (ex.debug)
            px_set_debug_handler(NULL);
        if (tmp_data)
            clear_and_pfree(tmp_data);
        pgp_free(ctx);
        mbuf_free(src);
        mbuf_free(dst);
        ereport(ERROR,
                (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
                 errmsg("%s", px_strerror(err))));
    }

    /* res_len includes VARHDRSZ */
    res_len = mbuf_steal_data(dst, &restmp);
    res = (bytea *) restmp;
    SET_VARSIZE(res, res_len);

    if (tmp_data)
        clear_and_pfree(tmp_data);
    pgp_free(ctx);
    mbuf_free(src);
    mbuf_free(dst);

    px_set_debug_handler(NULL);

    return res;
}

static bytea *
decrypt_internal(int is_pubenc, int need_text, text *data,
                 text *key, text *keypsw, text *args)
{
    int         err;
    MBuf       *src = NULL,
               *dst = NULL;
    uint8       tmp[VARHDRSZ];
    uint8      *restmp;
    bytea      *res;
    int         res_len;
    PGP_Context *ctx = NULL;
    struct debug_expect ex;
    int         got_unicode = 0;


    init_work(&ctx, need_text, args, &ex);

    src = mbuf_create_from_data((uint8 *) VARDATA(data),
                                VARSIZE(data) - VARHDRSZ);
    dst = mbuf_create(VARSIZE(data) + 2048);

    /*
     * reserve room for header
     */
    mbuf_append(dst, tmp, VARHDRSZ);

    /*
     * set key
     */
    if (is_pubenc)
    {
        uint8      *psw = NULL;
        int         psw_len = 0;
        MBuf       *kbuf;

        if (keypsw)
        {
            psw = (uint8 *) VARDATA(keypsw);
            psw_len = VARSIZE(keypsw) - VARHDRSZ;
        }
        kbuf = create_mbuf_from_vardata(key);
        err = pgp_set_pubkey(ctx, kbuf, psw, psw_len, 1);
        mbuf_free(kbuf);
    }
    else
        err = pgp_set_symkey(ctx, (uint8 *) VARDATA(key),
                             VARSIZE(key) - VARHDRSZ);

    /* decrypt */
    if (err >= 0)
    {
        err = pgp_decrypt(ctx, src, dst);

        if (ex.expect)
            check_expect(ctx, &ex);

        /* remember the setting */
        got_unicode = pgp_get_unicode_mode(ctx);
    }

    mbuf_free(src);
    pgp_free(ctx);

    if (err)
    {
        px_set_debug_handler(NULL);
        mbuf_free(dst);
        ereport(ERROR,
                (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
                 errmsg("%s", px_strerror(err))));
    }

    res_len = mbuf_steal_data(dst, &restmp);
    mbuf_free(dst);

    /* res_len includes VARHDRSZ */
    res = (bytea *) restmp;
    SET_VARSIZE(res, res_len);

    if (need_text && got_unicode)
    {
        text       *utf = convert_from_utf8(res);

        if (utf != res)
        {
            clear_and_pfree(res);
            res = utf;
        }
    }
    px_set_debug_handler(NULL);

    /*
     * add successful decryptions also into RNG
     */
    add_entropy(res, key, keypsw);

    return res;
}

/*
 * Wrappers for symmetric-key functions
 */
Datum
pgp_sym_encrypt_bytea(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        arg = PG_GETARG_BYTEA_P(2);

    res = encrypt_internal(0, 0, data, key, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(arg, 2);
    PG_RETURN_TEXT_P(res);
}

Datum
pgp_sym_encrypt_text(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        arg = PG_GETARG_BYTEA_P(2);

    res = encrypt_internal(0, 1, data, key, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(arg, 2);
    PG_RETURN_TEXT_P(res);
}


Datum
pgp_sym_decrypt_bytea(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        arg = PG_GETARG_BYTEA_P(2);

    res = decrypt_internal(0, 0, data, key, NULL, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(arg, 2);
    PG_RETURN_TEXT_P(res);
}

Datum
pgp_sym_decrypt_text(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        arg = PG_GETARG_BYTEA_P(2);

    res = decrypt_internal(0, 1, data, key, NULL, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(arg, 2);
    PG_RETURN_TEXT_P(res);
}

/*
 * Wrappers for public-key functions
 */

Datum
pgp_pub_encrypt_bytea(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        arg = PG_GETARG_BYTEA_P(2);

    res = encrypt_internal(1, 0, data, key, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(arg, 2);
    PG_RETURN_TEXT_P(res);
}

Datum
pgp_pub_encrypt_text(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        arg = PG_GETARG_BYTEA_P(2);

    res = encrypt_internal(1, 1, data, key, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(arg, 2);
    PG_RETURN_TEXT_P(res);
}


Datum
pgp_pub_decrypt_bytea(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *psw = NULL,
               *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        psw = PG_GETARG_BYTEA_P(2);
    if (PG_NARGS() > 3)
        arg = PG_GETARG_BYTEA_P(3);

    res = decrypt_internal(1, 0, data, key, psw, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(psw, 2);
    if (PG_NARGS() > 3)
        PG_FREE_IF_COPY(arg, 3);
    PG_RETURN_TEXT_P(res);
}

Datum
pgp_pub_decrypt_text(PG_FUNCTION_ARGS)
{
    bytea      *data,
               *key;
    text       *psw = NULL,
               *arg = NULL;
    text       *res;

    data = PG_GETARG_BYTEA_P(0);
    key = PG_GETARG_BYTEA_P(1);
    if (PG_NARGS() > 2)
        psw = PG_GETARG_BYTEA_P(2);
    if (PG_NARGS() > 3)
        arg = PG_GETARG_BYTEA_P(3);

    res = decrypt_internal(1, 1, data, key, psw, arg);

    PG_FREE_IF_COPY(data, 0);
    PG_FREE_IF_COPY(key, 1);
    if (PG_NARGS() > 2)
        PG_FREE_IF_COPY(psw, 2);
    if (PG_NARGS() > 3)
        PG_FREE_IF_COPY(arg, 3);
    PG_RETURN_TEXT_P(res);
}


/*
 * Wrappers for PGP ascii armor
 */

/*
 * Helper function for pgp_armor. Converts arrays of keys and values into
 * plain C arrays, and checks that they don't contain invalid characters.
 */
static int
parse_key_value_arrays(ArrayType *key_array, ArrayType *val_array,
                       char ***p_keys, char ***p_values)
{
    int         nkdims = ARR_NDIM(key_array);
    int         nvdims = ARR_NDIM(val_array);
    char      **keys,
              **values;
    Datum      *key_datums,
               *val_datums;
    bool       *key_nulls,
               *val_nulls;
    int         key_count,
                val_count;
    int         i;

    if (nkdims > 1 || nkdims != nvdims)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("wrong number of array subscripts")));
    if (nkdims == 0)
        return 0;

    deconstruct_array(key_array,
                      TEXTOID, -1, false, 'i',
                      &key_datums, &key_nulls, &key_count);

    deconstruct_array(val_array,
                      TEXTOID, -1, false, 'i',
                      &val_datums, &val_nulls, &val_count);

    if (key_count != val_count)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("mismatched array dimensions")));

    keys = (char **) palloc(sizeof(char *) * key_count);
    values = (char **) palloc(sizeof(char *) * val_count);

    for (i = 0; i < key_count; i++)
    {
        char       *v;

        /* Check that the key doesn't contain anything funny */
        if (key_nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("null value not allowed for header key")));

        v = TextDatumGetCString(key_datums[i]);

        if (!string_is_ascii(v))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                errmsg("header key must not contain non-ASCII characters")));
        if (strstr(v, ": "))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("header key must not contain \": \"")));
        if (strchr(v, '\n'))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("header key must not contain newlines")));
        keys[i] = v;

        /* And the same for the value */
        if (val_nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("null value not allowed for header value")));

        v = TextDatumGetCString(val_datums[i]);

        if (!string_is_ascii(v))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
              errmsg("header value must not contain non-ASCII characters")));
        if (strchr(v, '\n'))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("header value must not contain newlines")));

        values[i] = v;
    }

    *p_keys = keys;
    *p_values = values;
    return key_count;
}

Datum
pg_armor(PG_FUNCTION_ARGS)
{
    bytea      *data;
    text       *res;
    int         data_len;
    StringInfoData buf;
    int         num_headers;
    char      **keys = NULL,
              **values = NULL;

    data = PG_GETARG_BYTEA_P(0);
    data_len = VARSIZE(data) - VARHDRSZ;
    if (PG_NARGS() == 3)
    {
        num_headers = parse_key_value_arrays(PG_GETARG_ARRAYTYPE_P(1),
                                             PG_GETARG_ARRAYTYPE_P(2),
                                             &keys, &values);
    }
    else if (PG_NARGS() == 1)
        num_headers = 0;
    else
        elog(ERROR, "unexpected number of arguments %d", PG_NARGS());

    initStringInfo(&buf);

    pgp_armor_encode((uint8 *) VARDATA(data), data_len, &buf,
                     num_headers, keys, values);

    res = palloc(VARHDRSZ + buf.len);
    SET_VARSIZE(res, VARHDRSZ + buf.len);
    memcpy(VARDATA(res), buf.data, buf.len);
    pfree(buf.data);

    PG_FREE_IF_COPY(data, 0);
    PG_RETURN_TEXT_P(res);
}

Datum
pg_dearmor(PG_FUNCTION_ARGS)
{
    text       *data;
    bytea      *res;
    int         data_len;
    int         ret;
    StringInfoData buf;

    data = PG_GETARG_TEXT_P(0);
    data_len = VARSIZE(data) - VARHDRSZ;

    initStringInfo(&buf);

    ret = pgp_armor_decode((uint8 *) VARDATA(data), data_len, &buf);
    if (ret < 0)
        ereport(ERROR,
                (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
                 errmsg("%s", px_strerror(ret))));
    res = palloc(VARHDRSZ + buf.len);
    SET_VARSIZE(res, VARHDRSZ + buf.len);
    memcpy(VARDATA(res), buf.data, buf.len);
    pfree(buf.data);

    PG_FREE_IF_COPY(data, 0);
    PG_RETURN_TEXT_P(res);
}

/* cross-call state for pgp_armor_headers */
typedef struct
{
    int         nheaders;
    char      **keys;
    char      **values;
} pgp_armor_headers_state;

Datum
pgp_armor_headers(PG_FUNCTION_ARGS)
{
    FuncCallContext *funcctx;
    pgp_armor_headers_state *state;
    char       *utf8key;
    char       *utf8val;
    HeapTuple   tuple;
    TupleDesc   tupdesc;
    AttInMetadata *attinmeta;

    if (SRF_IS_FIRSTCALL())
    {
        text       *data = PG_GETARG_TEXT_PP(0);
        int         res;
        MemoryContext oldcontext;

        funcctx = SRF_FIRSTCALL_INIT();

        /* we need the state allocated in the multi call context */
        oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

        /* Build a tuple descriptor for our result type */
        if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
            elog(ERROR, "return type must be a row type");

        attinmeta = TupleDescGetAttInMetadata(tupdesc);
        funcctx->attinmeta = attinmeta;

        state = (pgp_armor_headers_state *) palloc(sizeof(pgp_armor_headers_state));

        res = pgp_extract_armor_headers((uint8 *) VARDATA_ANY(data),
                                        VARSIZE_ANY_EXHDR(data),
                                        &state->nheaders, &state->keys,
                                        &state->values);
        if (res < 0)
            ereport(ERROR,
                    (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
                     errmsg("%s", px_strerror(res))));

        MemoryContextSwitchTo(oldcontext);
        funcctx->user_fctx = state;
    }

    funcctx = SRF_PERCALL_SETUP();
    state = (pgp_armor_headers_state *) funcctx->user_fctx;

    if (funcctx->call_cntr >= state->nheaders)
        SRF_RETURN_DONE(funcctx);
    else
    {
        char       *values[2];

        /* we assume that the keys (and values) are in UTF-8. */
        utf8key = state->keys[funcctx->call_cntr];
        utf8val = state->values[funcctx->call_cntr];

        values[0] = pg_any_to_server(utf8key, strlen(utf8key), PG_UTF8);
        values[1] = pg_any_to_server(utf8val, strlen(utf8val), PG_UTF8);

        /* build a tuple */
        tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
        SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
    }
}



/*
 * Wrappers for PGP key id
 */

Datum
pgp_key_id_w(PG_FUNCTION_ARGS)
{
    bytea      *data;
    text       *res;
    int         res_len;
    MBuf       *buf;

    data = PG_GETARG_BYTEA_P(0);
    buf = create_mbuf_from_vardata(data);
    res = palloc(VARHDRSZ + 17);

    res_len = pgp_get_keyid(buf, VARDATA(res));
    mbuf_free(buf);
    if (res_len < 0)
        ereport(ERROR,
                (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
                 errmsg("%s", px_strerror(res_len))));
    SET_VARSIZE(res, VARHDRSZ + res_len);

    PG_FREE_IF_COPY(data, 0);
    PG_RETURN_TEXT_P(res);
}