commit e4856d1bbf1e3d0dd452a7a1b495464404007577
Author: David Goulet <dgoulet(a)torproject.org>
Date: Tue Jun 25 09:40:56 2019 -0400
trunnel: Add prop305 ESTABLISH_INTRO DoS cell extension
Signed-off-by: David Goulet <dgoulet(a)torproject.org>
---
src/trunnel/hs/cell_establish_intro.c | 469 ++++++++++++++++++++++++++++
src/trunnel/hs/cell_establish_intro.h | 157 ++++++++++
src/trunnel/hs/cell_establish_intro.trunnel | 19 ++
3 files changed, 645 insertions(+)
diff --git a/src/trunnel/hs/cell_establish_intro.c b/src/trunnel/hs/cell_establish_intro.c
index 99ceadbda..f31404c55 100644
--- a/src/trunnel/hs/cell_establish_intro.c
+++ b/src/trunnel/hs/cell_establish_intro.c
@@ -36,6 +36,185 @@ ssize_t trn_cell_extension_encoded_len(const trn_cell_extension_t *obj);
ssize_t trn_cell_extension_encode(uint8_t *output, size_t avail, const trn_cell_extension_t *input);
const char *trn_cell_extension_check(const trn_cell_extension_t *obj);
int trn_cell_extension_clear_errors(trn_cell_extension_t *obj);
+trn_cell_extension_dos_param_t *
+trn_cell_extension_dos_param_new(void)
+{
+ trn_cell_extension_dos_param_t *val = trunnel_calloc(1, sizeof(trn_cell_extension_dos_param_t));
+ if (NULL == val)
+ return NULL;
+ return val;
+}
+
+/** Release all storage held inside 'obj', but do not free 'obj'.
+ */
+static void
+trn_cell_extension_dos_param_clear(trn_cell_extension_dos_param_t *obj)
+{
+ (void) obj;
+}
+
+void
+trn_cell_extension_dos_param_free(trn_cell_extension_dos_param_t *obj)
+{
+ if (obj == NULL)
+ return;
+ trn_cell_extension_dos_param_clear(obj);
+ trunnel_memwipe(obj, sizeof(trn_cell_extension_dos_param_t));
+ trunnel_free_(obj);
+}
+
+uint8_t
+trn_cell_extension_dos_param_get_type(const trn_cell_extension_dos_param_t *inp)
+{
+ return inp->type;
+}
+int
+trn_cell_extension_dos_param_set_type(trn_cell_extension_dos_param_t *inp, uint8_t val)
+{
+ inp->type = val;
+ return 0;
+}
+uint64_t
+trn_cell_extension_dos_param_get_value(const trn_cell_extension_dos_param_t *inp)
+{
+ return inp->value;
+}
+int
+trn_cell_extension_dos_param_set_value(trn_cell_extension_dos_param_t *inp, uint64_t val)
+{
+ inp->value = val;
+ return 0;
+}
+const char *
+trn_cell_extension_dos_param_check(const trn_cell_extension_dos_param_t *obj)
+{
+ if (obj == NULL)
+ return "Object was NULL";
+ if (obj->trunnel_error_code_)
+ return "A set function failed on this object";
+ return NULL;
+}
+
+ssize_t
+trn_cell_extension_dos_param_encoded_len(const trn_cell_extension_dos_param_t *obj)
+{
+ ssize_t result = 0;
+
+ if (NULL != trn_cell_extension_dos_param_check(obj))
+ return -1;
+
+
+ /* Length of u8 type */
+ result += 1;
+
+ /* Length of u64 value */
+ result += 8;
+ return result;
+}
+int
+trn_cell_extension_dos_param_clear_errors(trn_cell_extension_dos_param_t *obj)
+{
+ int r = obj->trunnel_error_code_;
+ obj->trunnel_error_code_ = 0;
+ return r;
+}
+ssize_t
+trn_cell_extension_dos_param_encode(uint8_t *output, const size_t avail, const trn_cell_extension_dos_param_t *obj)
+{
+ ssize_t result = 0;
+ size_t written = 0;
+ uint8_t *ptr = output;
+ const char *msg;
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+ const ssize_t encoded_len = trn_cell_extension_dos_param_encoded_len(obj);
+#endif
+
+ if (NULL != (msg = trn_cell_extension_dos_param_check(obj)))
+ goto check_failed;
+
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+ trunnel_assert(encoded_len >= 0);
+#endif
+
+ /* Encode u8 type */
+ trunnel_assert(written <= avail);
+ if (avail - written < 1)
+ goto truncated;
+ trunnel_set_uint8(ptr, (obj->type));
+ written += 1; ptr += 1;
+
+ /* Encode u64 value */
+ trunnel_assert(written <= avail);
+ if (avail - written < 8)
+ goto truncated;
+ trunnel_set_uint64(ptr, trunnel_htonll(obj->value));
+ written += 8; ptr += 8;
+
+
+ trunnel_assert(ptr == output + written);
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+ {
+ trunnel_assert(encoded_len >= 0);
+ trunnel_assert((size_t)encoded_len == written);
+ }
+
+#endif
+
+ return written;
+
+ truncated:
+ result = -2;
+ goto fail;
+ check_failed:
+ (void)msg;
+ result = -1;
+ goto fail;
+ fail:
+ trunnel_assert(result < 0);
+ return result;
+}
+
+/** As trn_cell_extension_dos_param_parse(), but do not allocate the
+ * output object.
+ */
+static ssize_t
+trn_cell_extension_dos_param_parse_into(trn_cell_extension_dos_param_t *obj, const uint8_t *input, const size_t len_in)
+{
+ const uint8_t *ptr = input;
+ size_t remaining = len_in;
+ ssize_t result = 0;
+ (void)result;
+
+ /* Parse u8 type */
+ CHECK_REMAINING(1, truncated);
+ obj->type = (trunnel_get_uint8(ptr));
+ remaining -= 1; ptr += 1;
+
+ /* Parse u64 value */
+ CHECK_REMAINING(8, truncated);
+ obj->value = trunnel_ntohll(trunnel_get_uint64(ptr));
+ remaining -= 8; ptr += 8;
+ trunnel_assert(ptr + remaining == input + len_in);
+ return len_in - remaining;
+
+ truncated:
+ return -2;
+}
+
+ssize_t
+trn_cell_extension_dos_param_parse(trn_cell_extension_dos_param_t **output, const uint8_t *input, const size_t len_in)
+{
+ ssize_t result;
+ *output = trn_cell_extension_dos_param_new();
+ if (NULL == *output)
+ return -1;
+ result = trn_cell_extension_dos_param_parse_into(*output, input, len_in);
+ if (result < 0) {
+ trn_cell_extension_dos_param_free(*output);
+ *output = NULL;
+ }
+ return result;
+}
trn_cell_establish_intro_t *
trn_cell_establish_intro_new(void)
{
@@ -561,6 +740,296 @@ trn_cell_establish_intro_parse(trn_cell_establish_intro_t **output, const uint8_
}
return result;
}
+trn_cell_extension_dos_t *
+trn_cell_extension_dos_new(void)
+{
+ trn_cell_extension_dos_t *val = trunnel_calloc(1, sizeof(trn_cell_extension_dos_t));
+ if (NULL == val)
+ return NULL;
+ return val;
+}
+
+/** Release all storage held inside 'obj', but do not free 'obj'.
+ */
+static void
+trn_cell_extension_dos_clear(trn_cell_extension_dos_t *obj)
+{
+ (void) obj;
+ {
+
+ unsigned idx;
+ for (idx = 0; idx < TRUNNEL_DYNARRAY_LEN(&obj->params); ++idx) {
+ trn_cell_extension_dos_param_free(TRUNNEL_DYNARRAY_GET(&obj->params, idx));
+ }
+ }
+ TRUNNEL_DYNARRAY_WIPE(&obj->params);
+ TRUNNEL_DYNARRAY_CLEAR(&obj->params);
+}
+
+void
+trn_cell_extension_dos_free(trn_cell_extension_dos_t *obj)
+{
+ if (obj == NULL)
+ return;
+ trn_cell_extension_dos_clear(obj);
+ trunnel_memwipe(obj, sizeof(trn_cell_extension_dos_t));
+ trunnel_free_(obj);
+}
+
+uint8_t
+trn_cell_extension_dos_get_n_params(const trn_cell_extension_dos_t *inp)
+{
+ return inp->n_params;
+}
+int
+trn_cell_extension_dos_set_n_params(trn_cell_extension_dos_t *inp, uint8_t val)
+{
+ inp->n_params = val;
+ return 0;
+}
+size_t
+trn_cell_extension_dos_getlen_params(const trn_cell_extension_dos_t *inp)
+{
+ return TRUNNEL_DYNARRAY_LEN(&inp->params);
+}
+
+struct trn_cell_extension_dos_param_st *
+trn_cell_extension_dos_get_params(trn_cell_extension_dos_t *inp, size_t idx)
+{
+ return TRUNNEL_DYNARRAY_GET(&inp->params, idx);
+}
+
+ const struct trn_cell_extension_dos_param_st *
+trn_cell_extension_dos_getconst_params(const trn_cell_extension_dos_t *inp, size_t idx)
+{
+ return trn_cell_extension_dos_get_params((trn_cell_extension_dos_t*)inp, idx);
+}
+int
+trn_cell_extension_dos_set_params(trn_cell_extension_dos_t *inp, size_t idx, struct trn_cell_extension_dos_param_st * elt)
+{
+ trn_cell_extension_dos_param_t *oldval = TRUNNEL_DYNARRAY_GET(&inp->params, idx);
+ if (oldval && oldval != elt)
+ trn_cell_extension_dos_param_free(oldval);
+ return trn_cell_extension_dos_set0_params(inp, idx, elt);
+}
+int
+trn_cell_extension_dos_set0_params(trn_cell_extension_dos_t *inp, size_t idx, struct trn_cell_extension_dos_param_st * elt)
+{
+ TRUNNEL_DYNARRAY_SET(&inp->params, idx, elt);
+ return 0;
+}
+int
+trn_cell_extension_dos_add_params(trn_cell_extension_dos_t *inp, struct trn_cell_extension_dos_param_st * elt)
+{
+#if SIZE_MAX >= UINT8_MAX
+ if (inp->params.n_ == UINT8_MAX)
+ goto trunnel_alloc_failed;
+#endif
+ TRUNNEL_DYNARRAY_ADD(struct trn_cell_extension_dos_param_st *, &inp->params, elt, {});
+ return 0;
+ trunnel_alloc_failed:
+ TRUNNEL_SET_ERROR_CODE(inp);
+ return -1;
+}
+
+struct trn_cell_extension_dos_param_st * *
+trn_cell_extension_dos_getarray_params(trn_cell_extension_dos_t *inp)
+{
+ return inp->params.elts_;
+}
+const struct trn_cell_extension_dos_param_st * const *
+trn_cell_extension_dos_getconstarray_params(const trn_cell_extension_dos_t *inp)
+{
+ return (const struct trn_cell_extension_dos_param_st * const *)trn_cell_extension_dos_getarray_params((trn_cell_extension_dos_t*)inp);
+}
+int
+trn_cell_extension_dos_setlen_params(trn_cell_extension_dos_t *inp, size_t newlen)
+{
+ struct trn_cell_extension_dos_param_st * *newptr;
+#if UINT8_MAX < SIZE_MAX
+ if (newlen > UINT8_MAX)
+ goto trunnel_alloc_failed;
+#endif
+ newptr = trunnel_dynarray_setlen(&inp->params.allocated_,
+ &inp->params.n_, inp->params.elts_, newlen,
+ sizeof(inp->params.elts_[0]), (trunnel_free_fn_t) trn_cell_extension_dos_param_free,
+ &inp->trunnel_error_code_);
+ if (newlen != 0 && newptr == NULL)
+ goto trunnel_alloc_failed;
+ inp->params.elts_ = newptr;
+ return 0;
+ trunnel_alloc_failed:
+ TRUNNEL_SET_ERROR_CODE(inp);
+ return -1;
+}
+const char *
+trn_cell_extension_dos_check(const trn_cell_extension_dos_t *obj)
+{
+ if (obj == NULL)
+ return "Object was NULL";
+ if (obj->trunnel_error_code_)
+ return "A set function failed on this object";
+ {
+ const char *msg;
+
+ unsigned idx;
+ for (idx = 0; idx < TRUNNEL_DYNARRAY_LEN(&obj->params); ++idx) {
+ if (NULL != (msg = trn_cell_extension_dos_param_check(TRUNNEL_DYNARRAY_GET(&obj->params, idx))))
+ return msg;
+ }
+ }
+ if (TRUNNEL_DYNARRAY_LEN(&obj->params) != obj->n_params)
+ return "Length mismatch for params";
+ return NULL;
+}
+
+ssize_t
+trn_cell_extension_dos_encoded_len(const trn_cell_extension_dos_t *obj)
+{
+ ssize_t result = 0;
+
+ if (NULL != trn_cell_extension_dos_check(obj))
+ return -1;
+
+
+ /* Length of u8 n_params */
+ result += 1;
+
+ /* Length of struct trn_cell_extension_dos_param params[n_params] */
+ {
+
+ unsigned idx;
+ for (idx = 0; idx < TRUNNEL_DYNARRAY_LEN(&obj->params); ++idx) {
+ result += trn_cell_extension_dos_param_encoded_len(TRUNNEL_DYNARRAY_GET(&obj->params, idx));
+ }
+ }
+ return result;
+}
+int
+trn_cell_extension_dos_clear_errors(trn_cell_extension_dos_t *obj)
+{
+ int r = obj->trunnel_error_code_;
+ obj->trunnel_error_code_ = 0;
+ return r;
+}
+ssize_t
+trn_cell_extension_dos_encode(uint8_t *output, const size_t avail, const trn_cell_extension_dos_t *obj)
+{
+ ssize_t result = 0;
+ size_t written = 0;
+ uint8_t *ptr = output;
+ const char *msg;
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+ const ssize_t encoded_len = trn_cell_extension_dos_encoded_len(obj);
+#endif
+
+ if (NULL != (msg = trn_cell_extension_dos_check(obj)))
+ goto check_failed;
+
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+ trunnel_assert(encoded_len >= 0);
+#endif
+
+ /* Encode u8 n_params */
+ trunnel_assert(written <= avail);
+ if (avail - written < 1)
+ goto truncated;
+ trunnel_set_uint8(ptr, (obj->n_params));
+ written += 1; ptr += 1;
+
+ /* Encode struct trn_cell_extension_dos_param params[n_params] */
+ {
+
+ unsigned idx;
+ for (idx = 0; idx < TRUNNEL_DYNARRAY_LEN(&obj->params); ++idx) {
+ trunnel_assert(written <= avail);
+ result = trn_cell_extension_dos_param_encode(ptr, avail - written, TRUNNEL_DYNARRAY_GET(&obj->params, idx));
+ if (result < 0)
+ goto fail; /* XXXXXXX !*/
+ written += result; ptr += result;
+ }
+ }
+
+
+ trunnel_assert(ptr == output + written);
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+ {
+ trunnel_assert(encoded_len >= 0);
+ trunnel_assert((size_t)encoded_len == written);
+ }
+
+#endif
+
+ return written;
+
+ truncated:
+ result = -2;
+ goto fail;
+ check_failed:
+ (void)msg;
+ result = -1;
+ goto fail;
+ fail:
+ trunnel_assert(result < 0);
+ return result;
+}
+
+/** As trn_cell_extension_dos_parse(), but do not allocate the output
+ * object.
+ */
+static ssize_t
+trn_cell_extension_dos_parse_into(trn_cell_extension_dos_t *obj, const uint8_t *input, const size_t len_in)
+{
+ const uint8_t *ptr = input;
+ size_t remaining = len_in;
+ ssize_t result = 0;
+ (void)result;
+
+ /* Parse u8 n_params */
+ CHECK_REMAINING(1, truncated);
+ obj->n_params = (trunnel_get_uint8(ptr));
+ remaining -= 1; ptr += 1;
+
+ /* Parse struct trn_cell_extension_dos_param params[n_params] */
+ TRUNNEL_DYNARRAY_EXPAND(trn_cell_extension_dos_param_t *, &obj->params, obj->n_params, {});
+ {
+ trn_cell_extension_dos_param_t * elt;
+ unsigned idx;
+ for (idx = 0; idx < obj->n_params; ++idx) {
+ result = trn_cell_extension_dos_param_parse(&elt, ptr, remaining);
+ if (result < 0)
+ goto relay_fail;
+ trunnel_assert((size_t)result <= remaining);
+ remaining -= result; ptr += result;
+ TRUNNEL_DYNARRAY_ADD(trn_cell_extension_dos_param_t *, &obj->params, elt, {trn_cell_extension_dos_param_free(elt);});
+ }
+ }
+ trunnel_assert(ptr + remaining == input + len_in);
+ return len_in - remaining;
+
+ truncated:
+ return -2;
+ relay_fail:
+ trunnel_assert(result < 0);
+ return result;
+ trunnel_alloc_failed:
+ return -1;
+}
+
+ssize_t
+trn_cell_extension_dos_parse(trn_cell_extension_dos_t **output, const uint8_t *input, const size_t len_in)
+{
+ ssize_t result;
+ *output = trn_cell_extension_dos_new();
+ if (NULL == *output)
+ return -1;
+ result = trn_cell_extension_dos_parse_into(*output, input, len_in);
+ if (result < 0) {
+ trn_cell_extension_dos_free(*output);
+ *output = NULL;
+ }
+ return result;
+}
trn_cell_intro_established_t *
trn_cell_intro_established_new(void)
{
diff --git a/src/trunnel/hs/cell_establish_intro.h b/src/trunnel/hs/cell_establish_intro.h
index 1908645aa..cc3797fc9 100644
--- a/src/trunnel/hs/cell_establish_intro.h
+++ b/src/trunnel/hs/cell_establish_intro.h
@@ -10,6 +10,15 @@
struct trn_cell_extension_st;
#define TRUNNEL_SHA3_256_LEN 32
+#define TRUNNEL_CELL_EXTENSION_TYPE_DOS 1
+#if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_TRN_CELL_EXTENSION_DOS_PARAM)
+struct trn_cell_extension_dos_param_st {
+ uint8_t type;
+ uint64_t value;
+ uint8_t trunnel_error_code_;
+};
+#endif
+typedef struct trn_cell_extension_dos_param_st trn_cell_extension_dos_param_t;
#if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_TRN_CELL_ESTABLISH_INTRO)
struct trn_cell_establish_intro_st {
const uint8_t *start_cell;
@@ -26,6 +35,14 @@ struct trn_cell_establish_intro_st {
};
#endif
typedef struct trn_cell_establish_intro_st trn_cell_establish_intro_t;
+#if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_TRN_CELL_EXTENSION_DOS)
+struct trn_cell_extension_dos_st {
+ uint8_t n_params;
+ TRUNNEL_DYNARRAY_HEAD(, struct trn_cell_extension_dos_param_st *) params;
+ uint8_t trunnel_error_code_;
+};
+#endif
+typedef struct trn_cell_extension_dos_st trn_cell_extension_dos_t;
#if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_TRN_CELL_INTRO_ESTABLISHED)
struct trn_cell_intro_established_st {
struct trn_cell_extension_st *extensions;
@@ -33,6 +50,62 @@ struct trn_cell_intro_established_st {
};
#endif
typedef struct trn_cell_intro_established_st trn_cell_intro_established_t;
+/** Return a newly allocated trn_cell_extension_dos_param with all
+ * elements set to zero.
+ */
+trn_cell_extension_dos_param_t *trn_cell_extension_dos_param_new(void);
+/** Release all storage held by the trn_cell_extension_dos_param in
+ * 'victim'. (Do nothing if 'victim' is NULL.)
+ */
+void trn_cell_extension_dos_param_free(trn_cell_extension_dos_param_t *victim);
+/** Try to parse a trn_cell_extension_dos_param from the buffer in
+ * 'input', using up to 'len_in' bytes from the input buffer. On
+ * success, return the number of bytes consumed and set *output to the
+ * newly allocated trn_cell_extension_dos_param_t. On failure, return
+ * -2 if the input appears truncated, and -1 if the input is otherwise
+ * invalid.
+ */
+ssize_t trn_cell_extension_dos_param_parse(trn_cell_extension_dos_param_t **output, const uint8_t *input, const size_t len_in);
+/** Return the number of bytes we expect to need to encode the
+ * trn_cell_extension_dos_param in 'obj'. On failure, return a
+ * negative value. Note that this value may be an overestimate, and
+ * can even be an underestimate for certain unencodeable objects.
+ */
+ssize_t trn_cell_extension_dos_param_encoded_len(const trn_cell_extension_dos_param_t *obj);
+/** Try to encode the trn_cell_extension_dos_param from 'input' into
+ * the buffer at 'output', using up to 'avail' bytes of the output
+ * buffer. On success, return the number of bytes used. On failure,
+ * return -2 if the buffer was not long enough, and -1 if the input
+ * was invalid.
+ */
+ssize_t trn_cell_extension_dos_param_encode(uint8_t *output, size_t avail, const trn_cell_extension_dos_param_t *input);
+/** Check whether the internal state of the
+ * trn_cell_extension_dos_param in 'obj' is consistent. Return NULL if
+ * it is, and a short message if it is not.
+ */
+const char *trn_cell_extension_dos_param_check(const trn_cell_extension_dos_param_t *obj);
+/** Clear any errors that were set on the object 'obj' by its setter
+ * functions. Return true iff errors were cleared.
+ */
+int trn_cell_extension_dos_param_clear_errors(trn_cell_extension_dos_param_t *obj);
+/** Return the value of the type field of the
+ * trn_cell_extension_dos_param_t in 'inp'
+ */
+uint8_t trn_cell_extension_dos_param_get_type(const trn_cell_extension_dos_param_t *inp);
+/** Set the value of the type field of the
+ * trn_cell_extension_dos_param_t in 'inp' to 'val'. Return 0 on
+ * success; return -1 and set the error code on 'inp' on failure.
+ */
+int trn_cell_extension_dos_param_set_type(trn_cell_extension_dos_param_t *inp, uint8_t val);
+/** Return the value of the value field of the
+ * trn_cell_extension_dos_param_t in 'inp'
+ */
+uint64_t trn_cell_extension_dos_param_get_value(const trn_cell_extension_dos_param_t *inp);
+/** Set the value of the value field of the
+ * trn_cell_extension_dos_param_t in 'inp' to 'val'. Return 0 on
+ * success; return -1 and set the error code on 'inp' on failure.
+ */
+int trn_cell_extension_dos_param_set_value(trn_cell_extension_dos_param_t *inp, uint64_t val);
/** Return a newly allocated trn_cell_establish_intro with all
* elements set to zero.
*/
@@ -216,6 +289,90 @@ const uint8_t * trn_cell_establish_intro_getconstarray_sig(const trn_cell_estab
* -1 and set the error code on 'inp' on failure.
*/
int trn_cell_establish_intro_setlen_sig(trn_cell_establish_intro_t *inp, size_t newlen);
+/** Return a newly allocated trn_cell_extension_dos with all elements
+ * set to zero.
+ */
+trn_cell_extension_dos_t *trn_cell_extension_dos_new(void);
+/** Release all storage held by the trn_cell_extension_dos in
+ * 'victim'. (Do nothing if 'victim' is NULL.)
+ */
+void trn_cell_extension_dos_free(trn_cell_extension_dos_t *victim);
+/** Try to parse a trn_cell_extension_dos from the buffer in 'input',
+ * using up to 'len_in' bytes from the input buffer. On success,
+ * return the number of bytes consumed and set *output to the newly
+ * allocated trn_cell_extension_dos_t. On failure, return -2 if the
+ * input appears truncated, and -1 if the input is otherwise invalid.
+ */
+ssize_t trn_cell_extension_dos_parse(trn_cell_extension_dos_t **output, const uint8_t *input, const size_t len_in);
+/** Return the number of bytes we expect to need to encode the
+ * trn_cell_extension_dos in 'obj'. On failure, return a negative
+ * value. Note that this value may be an overestimate, and can even be
+ * an underestimate for certain unencodeable objects.
+ */
+ssize_t trn_cell_extension_dos_encoded_len(const trn_cell_extension_dos_t *obj);
+/** Try to encode the trn_cell_extension_dos from 'input' into the
+ * buffer at 'output', using up to 'avail' bytes of the output buffer.
+ * On success, return the number of bytes used. On failure, return -2
+ * if the buffer was not long enough, and -1 if the input was invalid.
+ */
+ssize_t trn_cell_extension_dos_encode(uint8_t *output, size_t avail, const trn_cell_extension_dos_t *input);
+/** Check whether the internal state of the trn_cell_extension_dos in
+ * 'obj' is consistent. Return NULL if it is, and a short message if
+ * it is not.
+ */
+const char *trn_cell_extension_dos_check(const trn_cell_extension_dos_t *obj);
+/** Clear any errors that were set on the object 'obj' by its setter
+ * functions. Return true iff errors were cleared.
+ */
+int trn_cell_extension_dos_clear_errors(trn_cell_extension_dos_t *obj);
+/** Return the value of the n_params field of the
+ * trn_cell_extension_dos_t in 'inp'
+ */
+uint8_t trn_cell_extension_dos_get_n_params(const trn_cell_extension_dos_t *inp);
+/** Set the value of the n_params field of the
+ * trn_cell_extension_dos_t in 'inp' to 'val'. Return 0 on success;
+ * return -1 and set the error code on 'inp' on failure.
+ */
+int trn_cell_extension_dos_set_n_params(trn_cell_extension_dos_t *inp, uint8_t val);
+/** Return the length of the dynamic array holding the params field of
+ * the trn_cell_extension_dos_t in 'inp'.
+ */
+size_t trn_cell_extension_dos_getlen_params(const trn_cell_extension_dos_t *inp);
+/** Return the element at position 'idx' of the dynamic array field
+ * params of the trn_cell_extension_dos_t in 'inp'.
+ */
+struct trn_cell_extension_dos_param_st * trn_cell_extension_dos_get_params(trn_cell_extension_dos_t *inp, size_t idx);
+/** As trn_cell_extension_dos_get_params, but take and return a const
+ * pointer
+ */
+ const struct trn_cell_extension_dos_param_st * trn_cell_extension_dos_getconst_params(const trn_cell_extension_dos_t *inp, size_t idx);
+/** Change the element at position 'idx' of the dynamic array field
+ * params of the trn_cell_extension_dos_t in 'inp', so that it will
+ * hold the value 'elt'. Free the previous value, if any.
+ */
+int trn_cell_extension_dos_set_params(trn_cell_extension_dos_t *inp, size_t idx, struct trn_cell_extension_dos_param_st * elt);
+/** As trn_cell_extension_dos_set_params, but does not free the
+ * previous value.
+ */
+int trn_cell_extension_dos_set0_params(trn_cell_extension_dos_t *inp, size_t idx, struct trn_cell_extension_dos_param_st * elt);
+/** Append a new element 'elt' to the dynamic array field params of
+ * the trn_cell_extension_dos_t in 'inp'.
+ */
+int trn_cell_extension_dos_add_params(trn_cell_extension_dos_t *inp, struct trn_cell_extension_dos_param_st * elt);
+/** Return a pointer to the variable-length array field params of
+ * 'inp'.
+ */
+struct trn_cell_extension_dos_param_st * * trn_cell_extension_dos_getarray_params(trn_cell_extension_dos_t *inp);
+/** As trn_cell_extension_dos_get_params, but take and return a const
+ * pointer
+ */
+const struct trn_cell_extension_dos_param_st * const * trn_cell_extension_dos_getconstarray_params(const trn_cell_extension_dos_t *inp);
+/** Change the length of the variable-length array field params of
+ * 'inp' to 'newlen'.Fill extra elements with NULL; free removed
+ * elements. Return 0 on success; return -1 and set the error code on
+ * 'inp' on failure.
+ */
+int trn_cell_extension_dos_setlen_params(trn_cell_extension_dos_t *inp, size_t newlen);
/** Return a newly allocated trn_cell_intro_established with all
* elements set to zero.
*/
diff --git a/src/trunnel/hs/cell_establish_intro.trunnel b/src/trunnel/hs/cell_establish_intro.trunnel
index 011ee62a1..08a110953 100644
--- a/src/trunnel/hs/cell_establish_intro.trunnel
+++ b/src/trunnel/hs/cell_establish_intro.trunnel
@@ -39,3 +39,22 @@ struct trn_cell_intro_established {
/* Extension(s). Reserved fields. */
struct trn_cell_extension extensions;
};
+
+/*
+ * ESTABLISH_INTRO cell extensions.
+ */
+
+const TRUNNEL_CELL_EXTENSION_TYPE_DOS = 0x01;
+
+/*
+ * DoS Parameters Extension. See proposal 305 for more details.
+ */
+struct trn_cell_extension_dos_param {
+ u8 type;
+ u64 value;
+};
+
+struct trn_cell_extension_dos {
+ u8 n_params;
+ struct trn_cell_extension_dos_param params[n_params];
+};
