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hs: Ignore unparseable v3 introduction point

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It is possible that at some point in time a client will encounter unknown or
new fields for an introduction point in a descriptor so let them ignore it for
forward compatibility.

Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2017-05-10 09:40:26 -04:00
parent f6df433b91
commit 82dee76740
2 changed files with 9 additions and 21 deletions
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27
src/or/hs_descriptor.c
View File

@ -1747,18 +1747,13 @@ decode_introduction_point(const hs_descriptor_t *desc, const char *start)
/* Given a descriptor string at <b>data</b>, decode all possible introduction
* points that we can find. Add the introduction point object to desc_enc as we
* find them. Return 0 on success.
*
* On error, a negative value is returned. It is possible that some intro
* point object have been added to the desc_enc, they should be considered
* invalid. One single bad encoded introduction point will make this function
* return an error. */
STATIC int
* find them. This function can't fail and it is possible that zero
* introduction points can be decoded. */
static void
decode_intro_points(const hs_descriptor_t *desc,
hs_desc_encrypted_data_t *desc_enc,
const char *data)
{
int retval = -1;
smartlist_t *chunked_desc = smartlist_new();
smartlist_t *intro_points = smartlist_new();
@ -1799,22 +1794,19 @@ decode_intro_points(const hs_descriptor_t *desc,
SMARTLIST_FOREACH_BEGIN(intro_points, const char *, intro_point) {
hs_desc_intro_point_t *ip = decode_introduction_point(desc, intro_point);
if (!ip) {
/* Malformed introduction point section. Stop right away, this
* descriptor shouldn't be used. */
goto err;
/* Malformed introduction point section. We'll ignore this introduction
* point and continue parsing. New or unknown fields are possible for
* forward compatibility. */
continue;
}
smartlist_add(desc_enc->intro_points, ip);
} SMARTLIST_FOREACH_END(intro_point);
done:
retval = 0;
err:
SMARTLIST_FOREACH(chunked_desc, char *, a, tor_free(a));
smartlist_free(chunked_desc);
SMARTLIST_FOREACH(intro_points, char *, a, tor_free(a));
smartlist_free(intro_points);
return retval;
}
/* Return 1 iff the given base64 encoded signature in b64_sig from the encoded
* descriptor in encoded_desc validates the descriptor content. */
@ -2040,9 +2032,8 @@ desc_decode_encrypted_v3(const hs_descriptor_t *desc,
/* Initialize the descriptor's introduction point list before we start
* decoding. Having 0 intro point is valid. Then decode them all. */
desc_encrypted_out->intro_points = smartlist_new();
if (decode_intro_points(desc, desc_encrypted_out, message) < 0) {
goto err;
}
decode_intro_points(desc, desc_encrypted_out, message);
/* Validation of maximum introduction points allowed. */
if (smartlist_len(desc_encrypted_out->intro_points) > MAX_INTRO_POINTS) {
log_warn(LD_REND, "Service descriptor contains too many introduction "

3
src/or/hs_descriptor.h
View File

@ -223,9 +223,6 @@ STATIC smartlist_t *decode_link_specifiers(const char *encoded);
STATIC hs_desc_intro_point_t *decode_introduction_point(
const hs_descriptor_t *desc,
const char *text);
STATIC int decode_intro_points(const hs_descriptor_t *desc,
hs_desc_encrypted_data_t *desc_enc,
const char *data);
STATIC int encrypted_data_length_is_valid(size_t len);
STATIC int cert_is_valid(tor_cert_t *cert, uint8_t type,
const char *log_obj_type);