md5_common.c

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/*-------------------------------------------------------------------------
 *
 * md5_common.c
 *    Routines shared between all MD5 implementations used for encrypted
 *    passwords.
 *
 * Sverre H. Huseby <sverrehu@online.no>
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/common/md5_common.c
 *
 *-------------------------------------------------------------------------
 */
 
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
 
#include "common/cryptohash.h"
#include "common/md5.h"
 
static void
bytesToHex(uint8 b[16], char *s)
{
    static const char *hex = "0123456789abcdef";
    int         q,
                w;
 
    for (q = 0, w = 0; q < 16; q++)
    {
        s[w++] = hex[(b[q] >> 4) & 0x0F];
        s[w++] = hex[b[q] & 0x0F];
    }
    s[w] = '\0';
}
 
/*
 *  pg_md5_hash
 *
 *  Calculates the MD5 sum of the bytes in a buffer.
 *
 *  SYNOPSIS      #include "md5.h"
 *                bool pg_md5_hash(const void *buff, size_t len, char *hexsum,
 *                                 const char **errstr)
 *
 *  INPUT         buff    the buffer containing the bytes that you want
 *                        the MD5 sum of.
 *                len     number of bytes in the buffer.
 *
 *  OUTPUT        hexsum  the MD5 sum as a '\0'-terminated string of
 *                        hexadecimal digits.  an MD5 sum is 16 bytes long.
 *                        each byte is represented by two hexadecimal
 *                        characters.  you thus need to provide an array
 *                        of 33 characters, including the trailing '\0'.
 *
 *                errstr  filled with a constant-string error message
 *                        on failure return; NULL on success.
 *
 *  RETURNS       false on failure (out of memory for internal buffers
 *                or MD5 computation failure) or true on success.
 *
 *  STANDARDS     MD5 is described in RFC 1321.
 *
 *  AUTHOR        Sverre H. Huseby <sverrehu@online.no>
 *
 */
 
bool
pg_md5_hash(const void *buff, size_t len, char *hexsum, const char **errstr)
{
    uint8       sum[MD5_DIGEST_LENGTH];
    pg_cryptohash_ctx *ctx;
 
    *errstr = NULL;
    ctx = pg_cryptohash_create(PG_MD5);
    if (ctx == NULL)
    {
        *errstr = pg_cryptohash_error(NULL);    /* returns OOM */
        return false;
    }
 
    if (pg_cryptohash_init(ctx) < 0 ||
        pg_cryptohash_update(ctx, buff, len) < 0 ||
        pg_cryptohash_final(ctx, sum, sizeof(sum)) < 0)
    {
        *errstr = pg_cryptohash_error(ctx);
        pg_cryptohash_free(ctx);
        return false;
    }
 
    bytesToHex(sum, hexsum);
    pg_cryptohash_free(ctx);
    return true;
}
 
/*
 * pg_md5_binary
 *
 * As above, except that the MD5 digest is returned as a binary string
 * (of size MD5_DIGEST_LENGTH) rather than being converted to ASCII hex.
 */
bool
pg_md5_binary(const void *buff, size_t len, uint8 *outbuf, const char **errstr)
{
    pg_cryptohash_ctx *ctx;
 
    *errstr = NULL;
    ctx = pg_cryptohash_create(PG_MD5);
    if (ctx == NULL)
    {
        *errstr = pg_cryptohash_error(NULL);    /* returns OOM */
        return false;
    }
 
    if (pg_cryptohash_init(ctx) < 0 ||
        pg_cryptohash_update(ctx, buff, len) < 0 ||
        pg_cryptohash_final(ctx, outbuf, MD5_DIGEST_LENGTH) < 0)
    {
        *errstr = pg_cryptohash_error(ctx);
        pg_cryptohash_free(ctx);
        return false;
    }
 
    pg_cryptohash_free(ctx);
    return true;
}
 
 
/*
 * Computes MD5 checksum of "passwd" (a null-terminated string) followed
 * by "salt" (which need not be null-terminated).
 *
 * Output format is "md5" followed by a 32-hex-digit MD5 checksum.
 * Hence, the output buffer "buf" must be at least 36 bytes long.
 *
 * Returns true if okay, false on error with *errstr providing some
 * error context.
 */
bool
pg_md5_encrypt(const char *passwd, const uint8 *salt, size_t salt_len,
               char *buf, const char **errstr)
{
    size_t      passwd_len = strlen(passwd);
 
    /* +1 here is just to avoid risk of unportable malloc(0) */
    char       *crypt_buf = malloc(passwd_len + salt_len + 1);
    bool        ret;
 
    if (!crypt_buf)
    {
        *errstr = _("out of memory");
        return false;
    }
 
    /*
     * Place salt at the end because it may be known by users trying to crack
     * the MD5 output.
     */
    memcpy(crypt_buf, passwd, passwd_len);
    memcpy(crypt_buf + passwd_len, salt, salt_len);
 
    strcpy(buf, "md5");
    ret = pg_md5_hash(crypt_buf, passwd_len + salt_len, buf + 3, errstr);
 
    free(crypt_buf);
 
    return ret;
}