commit 82dee76740062c00e98a7005f773672065abcf96 Author: David Goulet dgoulet@torproject.org Date: Wed May 10 09:40:26 2017 -0400

hs: Ignore unparseable v3 introduction point

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 --- src/or/hs_descriptor.c | 27 +++++++++------------------ src/or/hs_descriptor.h | 3 --- 2 files changed, 9 insertions(+), 21 deletions(-)

diff --git a/src/or/hs_descriptor.c b/src/or/hs_descriptor.c index 2a000f5..b55f966 100644 --- a/src/or/hs_descriptor.c +++ b/src/or/hs_descriptor.c @@ -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 " diff --git a/src/or/hs_descriptor.h b/src/or/hs_descriptor.h index b8b9479..58c4089 100644 --- a/src/or/hs_descriptor.h +++ b/src/or/hs_descriptor.h @@ -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);