src/lib-otp/otp-parse.c

/*
 * OTP extended response parser.
 *
 * Copyright (c) 2006 Andrey Panin <pazke@donpac.ru>
 *
 * This software is released under the MIT license.
 */

#include "lib.h"
#include "buffer.h"
#include "str.h"
#include "strfuncs.h"
#include "hex-binary.h"

#include "otp.h"

#include <ctype.h>

#define IS_LWS(c) ((c) == ' ' || (c) == '\t')

static inline const char *otp_skip_lws(const char *data)
{
    while (*data != '\0' && IS_LWS(*data))
        data++;
    return data;
}

static inline bool otp_check_tail(const char *data)
{
    data = otp_skip_lws(data);

    return *data != 0;
}

int otp_read_hex(const char *data, const char **endptr, unsigned char *hash)
{
    string_t *str;
    buffer_t buf;
    unsigned int i = 0;

    if (data == NULL)
        return -1;

    str = t_str_new(18);
    buffer_create_from_data(&buf, hash, OTP_HASH_SIZE);

    while (*data != '\0') {
        char c = *data;

        if (i_isxdigit(c)) {
            str_append_c(str, c);
            if (++i == OTP_HASH_SIZE * 2) {
                data++;
                break;
            }
        } else if (!IS_LWS(c)) {
            *endptr = data;
            return -1;
        }
        data++;
    }

    *endptr = data;

    if (i < OTP_HASH_SIZE * 2)
        return -1;

    return hex_to_binary(str_c(str), &buf);
}

#define add_word() do { \
    tmp = otp_lookup_word(str_c(word)); \
    buffer_append(&buf, &tmp, sizeof(tmp)); \
    count++; \
} while (0)

int otp_read_words(const char *data, const char **endptr, unsigned char *hash)
{
    bool space = FALSE;
    unsigned int len = 0, count = 0;
    unsigned int parity = 0, bits[OTP_WORDS_NUMBER], tmp;
    string_t *word;
    buffer_t buf;

    if (data == NULL)
        return -1;

    word = t_str_new(8);

    data = otp_skip_lws(data);

    buffer_create_from_data(&buf, bits, sizeof(bits));

    for (; *data != '\0' && (count < OTP_WORDS_NUMBER); data++) {
        char c = *data;

        if (space) {
            if (IS_LWS(c))
                continue;
            else if (i_isalpha(c)) {
                str_append_c(word, c);
                space = FALSE;
                len = 1;
                continue;
            }
        } else {
            if (i_isalpha(c)) {
                if (++len > OTP_MAX_WORD_LEN) {
                    count = 0;
                    break;
                }
                str_append_c(word, c);
                continue;
            } else if (IS_LWS(c)) {
                add_word();
                str_truncate(word, 0);
                space = TRUE;
                continue;
            }
        }
        break;
    }

    if ((str_len(word) > 0) && (count == OTP_WORDS_NUMBER - 1))
        add_word();

    if (endptr != NULL)
        *endptr = data;

    if (count < OTP_WORDS_NUMBER)
        return -1;

    hash[0] = bits[0] >> 3;
    hash[1] = ((bits[0] & 7) << 5) | (bits[1] >> 6);
    hash[2] = ((bits[1] & 0x3f) << 2) | (bits[2] >> 9);
    hash[3] = (bits[2] >> 1) & 0xff;
    hash[4] = ((bits[2] & 3) << 7) | (bits[3] >> 4);
    hash[5] = ((bits[3] & 15) << 4) | (bits[4] >> 7);
    hash[6] = ((bits[4] & 0x7f) << 1) | (bits[5] >> 10);
    hash[7] = (bits[5] >> 2) & 0xff;
    parity = bits[5] & 3;

    return otp_parity(hash) != parity ? 1 : 0;
}

int otp_read_new_params(const char *data, const char **endptr,
            struct otp_state *state)
{
    const char *p, *s;
    unsigned int i = 0;
    int algo;

    s = p = data;

    while ((*p != 0) && !IS_LWS(*p)) p++;
    if (*p == 0)
        return -1;

    algo = digest_find(t_strdup_until(s, p++));
    if (algo < 0)
        return -2;
    state->algo = algo;

    s = p;
    if (str_parse_int(s, &state->seq, &p) < 0 || !IS_LWS(*p))
        return -3;
    p++;

    while (i_isalnum(*p) && (i < OTP_MAX_SEED_LEN))
        state->seed[i++] = i_tolower(*p++);
    state->seed[i] = 0;

    *endptr = p;
    return 0;
}

int otp_parse_response(const char *data, unsigned char *hash, bool hex)
{
    const char *end;
    int ret = hex ? otp_read_hex(data, &end, hash) :
            otp_read_words(data, &end, hash);
    if (ret < 0)
        return ret;

    return otp_check_tail(end) ? 1 : 0;
}

int otp_parse_init_response(const char *data, struct otp_state *new_state,
                unsigned char *hash, bool hex, const char **error)
{
    const char *end;
    int ret = hex ? otp_read_hex(data, &end, hash) :
            otp_read_words(data, &end, hash);
    if (ret < 0) {
        *error = "invalid current OTP";
        return ret;
    }

    end = otp_skip_lws(end);
    if (*end++ != ':') {
        *error = "missing colon";
        return -1;
    }

    ret = otp_read_new_params(end, &end, new_state);
    if (ret < 0) {
        *error = "invalid OTP parameters";
        return -1;
    }

    end = otp_skip_lws(end);
    if (*end++ != ':') {
        *error = "missing colon";
        return -1;
    }

    ret = hex ? otp_read_hex(end, &end, new_state->hash) :
            otp_read_words(end, &end, new_state->hash);
    if (ret < 0) {
        *error = "invalid new OTP";
        return -1;
    }

    if (otp_check_tail(end)) {
        *error = "trailing garbage found";
        return -1;
    }

    return 0;
}

int otp_parse_dbentry(const char *text, struct otp_state *state)
{
    const char *end;
    int ret;

    ret = otp_read_new_params(text, &end, state);
    if (ret != 0)
        return ret;

    if (*end++ != ' ')
        return -1;

    return otp_read_hex(end, &end, state->hash);
}

const char *otp_print_dbentry(const struct otp_state *state)
{
    return t_strdup_printf("%s %d %s %s", digest_name(state->algo),
                state->seq, state->seed,
                binary_to_hex(state->hash, 8));
}