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Write dynamic DH parameters to a file.
Instead of only writing the dynamic DH prime modulus to a file, write the whole DH parameters set for forward compatibility. At the moment we only accept '2' as the group generator. The DH parameters gets stored in base64-ed DER format to the 'dynamic_dh_params' file.
This commit is contained in:
George Kadianakis
parent
f28014bf1a
commit
055d6c01ff
@ -1852,44 +1852,66 @@ crypto_generate_dynamic_dh_modulus(void)
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return dynamic_dh_modulus;
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}
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/** Store our dynamic DH modulus to <b>fname</b> for future use. */
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/** Store our dynamic DH modulus (and its group parameters) to
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<b>fname</b> for future use. */
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static int
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crypto_store_dynamic_dh_modulus(const char *fname)
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{
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FILE *fp = NULL;
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int len, new_len;
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DH *dh = NULL;
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unsigned char *dh_string_repr = NULL, *cp = NULL;
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char *base64_encoded_dh = NULL;
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int retval = -1;
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file_status_t fname_status;
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tor_assert(fname);
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fname_status = file_status(fname);
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if (fname_status == FN_FILE) {
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/* If the fname is a file, then the dynamic DH modulus is already stored.*/
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retval = 0;
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goto done;
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} else if (fname_status != FN_NOENT) {
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log_info(LD_GENERAL, "Dynamic DH modulus filename is occupied.");
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if (!dh_param_p_tls) {
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log_info(LD_CRYPTO, "Tried to store a DH modulus that does not exist.");
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goto done;
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}
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tor_assert(fname_status == FN_NOENT);
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if (!(dh = DH_new()))
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goto done;
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if (!(dh->p = BN_dup(dh_param_p_tls)))
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goto done;
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if (!(dh->g = BN_new()))
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goto done;
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if (!BN_set_word(dh->g, DH_GENERATOR))
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goto done;
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if (!(fp = fopen(fname, "w"))) {
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log_notice(LD_GENERAL, "Error while creating dynamic DH modulus file.");
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len = i2d_DHparams(dh, NULL);
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if (len < 0) {
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log_warn(LD_CRYPTO, "Error occured while DER encoding DH modulus (1).");
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goto done;
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}
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if (BN_print_fp(fp, dh_param_p_tls) == 0) {
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log_warn(LD_GENERAL, "Error while printing dynamic DH modulus to file.");
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cp = dh_string_repr = tor_malloc_zero(len+1);
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len = i2d_DHparams(dh, &cp);
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if ((len < 0) || ((cp - dh_string_repr) != len)) {
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log_warn(LD_CRYPTO, "Error occured while DER encoding DH modulus (2).");
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goto done;
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}
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base64_encoded_dh = tor_malloc_zero(len * 2); /* should be enough */
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new_len = base64_encode(base64_encoded_dh, len * 2,
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(char *)dh_string_repr, len);
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if (new_len < 0) {
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log_warn(LD_CRYPTO, "Error occured while base64-encoding DH modulus.");
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goto done;
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}
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if (write_bytes_to_new_file(fname, base64_encoded_dh, new_len, 0) < 0) {
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log_info(LD_CRYPTO, "'%s' was already occupied.", fname);
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goto done;
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}
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retval = 0;
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done:
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if (fp)
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fclose(fp);
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if (dh)
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DH_free(dh);
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tor_free(dh_string_repr);
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tor_free(base64_encoded_dh);
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return retval;
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}
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@ -1901,52 +1923,62 @@ crypto_get_stored_dynamic_dh_modulus(const char *fname)
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{
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int retval;
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char *contents = NULL;
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DH *dh = NULL;
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int dh_codes;
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char *fname_new = NULL;
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BIGNUM *dynamic_dh_modulus = BN_new();
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DH *stored_dh = NULL;
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BIGNUM *dynamic_dh_modulus = NULL;
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int length = 0;
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unsigned char *base64_decoded_dh = NULL;
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const unsigned char *cp = NULL;
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tor_assert(fname);
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if (!dynamic_dh_modulus)
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goto err;
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contents = read_file_to_str(fname, RFTS_IGNORE_MISSING, NULL);
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if (!contents)
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goto err;
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if (!contents) {
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log_info(LD_CRYPTO, "Could not open file '%s'", fname);
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goto done; /*usually means that ENOENT. don't try to move file to broken.*/
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}
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retval = BN_hex2bn(&dynamic_dh_modulus, contents);
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if (!retval) {
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log_warn(LD_GENERAL, "Could not understand the dynamic DH modulus "
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"format in '%s'", fname);
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/* 'fname' contains the DH parameters stored in base64-ed DER
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format. We are only interested in the DH modulus. */
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cp = base64_decoded_dh = tor_malloc_zero(strlen(contents));
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length = base64_decode((char *)base64_decoded_dh, strlen(contents),
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contents, strlen(contents));
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if (length < 0) {
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log_warn(LD_CRYPTO, "Stored dynamic DH modulus seems corrupted (base64).");
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goto err;
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}
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{ /* validate the stored prime */
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dh = DH_new();
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if (!dh)
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goto err;
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stored_dh = d2i_DHparams(NULL, &cp, length);
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if ((!stored_dh) || (cp - base64_decoded_dh != length)) {
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log_warn(LD_CRYPTO, "Stored dynamic DH modulus seems corrupted (d2i).");
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goto err;
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}
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dh->p = BN_dup(dynamic_dh_modulus);
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dh->g = BN_new();
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BN_set_word(dh->g, DH_GENERATOR);
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retval = DH_check(dh, &dh_codes);
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{ /* check the cryptographic qualities of the stored dynamic DH modulus: */
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retval = DH_check(stored_dh, &dh_codes);
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if (!retval || dh_codes) {
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log_warn(LD_GENERAL, "Stored dynamic DH prime is not a safe prime.");
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log_warn(LD_CRYPTO, "Stored dynamic DH modulus is not a safe prime.");
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goto err;
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}
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retval = DH_size(dh);
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retval = DH_size(stored_dh);
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if (retval < DH_BYTES) {
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log_warn(LD_GENERAL, "Stored dynamic DH prime is smaller "
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log_warn(LD_CRYPTO, "Stored dynamic DH modulus is smaller "
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"than '%d' bits.", DH_BYTES*8);
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goto err;
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}
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if (!BN_is_word(stored_dh->g, 2)) {
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log_warn(LD_CRYPTO, "Stored dynamic DH parameters do not use '2' "
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"as the group generator.");
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goto err;
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}
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}
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{ /* log the dynamic DH modulus: */
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char *s = BN_bn2hex(dynamic_dh_modulus);
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char *s = BN_bn2hex(stored_dh->p);
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tor_assert(s);
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log_info(LD_OR, "Found stored dynamic DH modulus: [%s]", s);
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OPENSSL_free(s);
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@ -1957,31 +1989,34 @@ crypto_get_stored_dynamic_dh_modulus(const char *fname)
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err:
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{ /* move broken prime to $filename.broken */
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fname_new = tor_malloc(strlen(fname) + 8);
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/* no can do if these functions return error */
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strlcpy(fname_new, fname, strlen(fname) + 8);
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strlcat(fname_new, ".broken", strlen(fname) + 8);
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log_warn(LD_GENERAL, "Moving broken dynamic DH prime to '%s'.", fname_new);
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log_warn(LD_CRYPTO, "Moving broken dynamic DH prime to '%s'.", fname_new);
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if (replace_file(fname, fname_new))
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log_warn(LD_GENERAL, "Error while moving '%s' to '%s'.", fname, fname_new);
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log_notice(LD_CRYPTO, "Error while moving '%s' to '%s'.",
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fname, fname_new);
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tor_free(fname_new);
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}
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if (dynamic_dh_modulus) {
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BN_free(dynamic_dh_modulus);
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dynamic_dh_modulus = NULL;
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if (stored_dh) {
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DH_free(stored_dh);
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stored_dh = NULL;
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}
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done:
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tor_free(contents);
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if (dh)
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DH_free(dh);
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tor_free(base64_decoded_dh);
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if (stored_dh) {
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dynamic_dh_modulus = BN_dup(stored_dh->p);
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DH_free(stored_dh);
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}
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return dynamic_dh_modulus;
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}
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@ -2040,10 +2075,9 @@ crypto_set_tls_dh_prime(const char *dynamic_dh_modulus_fname)
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if (store_dh_prime_afterwards)
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/* save the new dynamic DH modulus to disk. */
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if (crypto_store_dynamic_dh_modulus(dynamic_dh_modulus_fname)) {
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log_notice(LD_GENERAL, "Failed while storing dynamic DH modulus. "
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log_notice(LD_CRYPTO, "Failed while storing dynamic DH modulus. "
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"Make sure your data directory is sane.");
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}
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}
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/** Initialize dh_param_p and dh_param_g if they are not already
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@ -1384,7 +1384,7 @@ options_act(const or_options_t *old_options)
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if (server_mode(options)) {
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if (!old_options) {
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if (options->DynamicDHGroups) {
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char *fname = get_datadir_fname2("keys", "dynamic_dh_modulus");
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char *fname = get_datadir_fname2("keys", "dynamic_dh_params");
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crypto_set_tls_dh_prime(fname);
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tor_free(fname);
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} else {
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@ -1392,7 +1392,7 @@ options_act(const or_options_t *old_options)
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}
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} else {
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if (options->DynamicDHGroups && !old_options->DynamicDHGroups) {
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char *fname = get_datadir_fname2("keys", "dynamic_dh_modulus");
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char *fname = get_datadir_fname2("keys", "dynamic_dh_params");
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crypto_set_tls_dh_prime(fname);
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tor_free(fname);
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} else if (!options->DynamicDHGroups && old_options->DynamicDHGroups) {
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@ -484,7 +484,6 @@ v3_authority_check_key_expiry(void)
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last_warned = now;
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}
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int
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router_initialize_tls_context(void)
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{
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