prop289: Add SENDME trunnel declaration

Signed-off-by: David Goulet <dgoulet@torproject.org>

4 files changed, 683 insertions, 0 deletions

diff --git a/src/trunnel/include.am b/src/trunnel/include.am
index 4f4f1d3624..82e7a66959 100644
--- a/src/trunnel/include.am
+++ b/src/trunnel/include.am
@@ -11,6 +11,7 @@ TRUNNELINPUTS = \
 	src/trunnel/link_handshake.trunnel \
 	src/trunnel/pwbox.trunnel \
 	src/trunnel/channelpadding_negotiation.trunnel \
+	src/trunnel/sendme.trunnel \
 	src/trunnel/socks5.trunnel \
 	src/trunnel/circpad_negotiation.trunnel
 
@@ -24,6 +25,7 @@ TRUNNELSOURCES = \
 	src/trunnel/hs/cell_introduce1.c \
 	src/trunnel/hs/cell_rendezvous.c \
 	src/trunnel/channelpadding_negotiation.c \
+	src/trunnel/sendme.c                    \
 	src/trunnel/socks5.c \
 	src/trunnel/netinfo.c \
 	src/trunnel/circpad_negotiation.c
@@ -40,6 +42,7 @@ TRUNNELHEADERS = \
 	src/trunnel/hs/cell_introduce1.h \
 	src/trunnel/hs/cell_rendezvous.h \
 	src/trunnel/channelpadding_negotiation.h \
+	src/trunnel/sendme.h                    \
 	src/trunnel/socks5.h                    \
 	src/trunnel/netinfo.h \
 	src/trunnel/circpad_negotiation.h
diff --git a/src/trunnel/sendme.c b/src/trunnel/sendme.c
new file mode 100644
index 0000000000..08f9ed5e91
--- /dev/null
+++ b/src/trunnel/sendme.c
@@ -0,0 +1,492 @@
+/* sendme.c -- generated by Trunnel v1.5.2.
+ * https://gitweb.torproject.org/trunnel.git
+ * You probably shouldn't edit this file.
+ */
+#include <stdlib.h>
+#include "trunnel-impl.h"
+
+#include "sendme.h"
+
+#define TRUNNEL_SET_ERROR_CODE(obj) \
+  do {                              \
+    (obj)->trunnel_error_code_ = 1; \
+  } while (0)
+
+#if defined(__COVERITY__) || defined(__clang_analyzer__)
+/* If we're running a static analysis tool, we don't want it to complain
+ * that some of our remaining-bytes checks are dead-code. */
+int sendme_deadcode_dummy__ = 0;
+#define OR_DEADCODE_DUMMY || sendme_deadcode_dummy__
+#else
+#define OR_DEADCODE_DUMMY
+#endif
+
+#define CHECK_REMAINING(nbytes, label)                           \
+  do {                                                           \
+    if (remaining < (nbytes) OR_DEADCODE_DUMMY) {                \
+      goto label;                                                \
+    }                                                            \
+  } while (0)
+
+sendme_cell_t *
+sendme_cell_new(void)
+{
+  sendme_cell_t *val = trunnel_calloc(1, sizeof(sendme_cell_t));
+  if (NULL == val)
+    return NULL;
+  return val;
+}
+
+/** Release all storage held inside 'obj', but do not free 'obj'.
+ */
+static void
+sendme_cell_clear(sendme_cell_t *obj)
+{
+  (void) obj;
+  TRUNNEL_DYNARRAY_WIPE(&obj->data);
+  TRUNNEL_DYNARRAY_CLEAR(&obj->data);
+}
+
+void
+sendme_cell_free(sendme_cell_t *obj)
+{
+  if (obj == NULL)
+    return;
+  sendme_cell_clear(obj);
+  trunnel_memwipe(obj, sizeof(sendme_cell_t));
+  trunnel_free_(obj);
+}
+
+uint8_t
+sendme_cell_get_version(const sendme_cell_t *inp)
+{
+  return inp->version;
+}
+int
+sendme_cell_set_version(sendme_cell_t *inp, uint8_t val)
+{
+  if (! ((val == 0 || val == 1))) {
+     TRUNNEL_SET_ERROR_CODE(inp);
+     return -1;
+  }
+  inp->version = val;
+  return 0;
+}
+uint16_t
+sendme_cell_get_data_len(const sendme_cell_t *inp)
+{
+  return inp->data_len;
+}
+int
+sendme_cell_set_data_len(sendme_cell_t *inp, uint16_t val)
+{
+  inp->data_len = val;
+  return 0;
+}
+size_t
+sendme_cell_getlen_data(const sendme_cell_t *inp)
+{
+  return TRUNNEL_DYNARRAY_LEN(&inp->data);
+}
+
+uint8_t
+sendme_cell_get_data(sendme_cell_t *inp, size_t idx)
+{
+  return TRUNNEL_DYNARRAY_GET(&inp->data, idx);
+}
+
+uint8_t
+sendme_cell_getconst_data(const sendme_cell_t *inp, size_t idx)
+{
+  return sendme_cell_get_data((sendme_cell_t*)inp, idx);
+}
+int
+sendme_cell_set_data(sendme_cell_t *inp, size_t idx, uint8_t elt)
+{
+  TRUNNEL_DYNARRAY_SET(&inp->data, idx, elt);
+  return 0;
+}
+int
+sendme_cell_add_data(sendme_cell_t *inp, uint8_t elt)
+{
+#if SIZE_MAX >= UINT16_MAX
+  if (inp->data.n_ == UINT16_MAX)
+    goto trunnel_alloc_failed;
+#endif
+  TRUNNEL_DYNARRAY_ADD(uint8_t, &inp->data, elt, {});
+  return 0;
+ trunnel_alloc_failed:
+  TRUNNEL_SET_ERROR_CODE(inp);
+  return -1;
+}
+
+uint8_t *
+sendme_cell_getarray_data(sendme_cell_t *inp)
+{
+  return inp->data.elts_;
+}
+const uint8_t  *
+sendme_cell_getconstarray_data(const sendme_cell_t *inp)
+{
+  return (const uint8_t  *)sendme_cell_getarray_data((sendme_cell_t*)inp);
+}
+int
+sendme_cell_setlen_data(sendme_cell_t *inp, size_t newlen)
+{
+  uint8_t *newptr;
+#if UINT16_MAX < SIZE_MAX
+  if (newlen > UINT16_MAX)
+    goto trunnel_alloc_failed;
+#endif
+  newptr = trunnel_dynarray_setlen(&inp->data.allocated_,
+                 &inp->data.n_, inp->data.elts_, newlen,
+                 sizeof(inp->data.elts_[0]), (trunnel_free_fn_t) NULL,
+                 &inp->trunnel_error_code_);
+  if (newlen != 0 && newptr == NULL)
+    goto trunnel_alloc_failed;
+  inp->data.elts_ = newptr;
+  return 0;
+ trunnel_alloc_failed:
+  TRUNNEL_SET_ERROR_CODE(inp);
+  return -1;
+}
+const char *
+sendme_cell_check(const sendme_cell_t *obj)
+{
+  if (obj == NULL)
+    return "Object was NULL";
+  if (obj->trunnel_error_code_)
+    return "A set function failed on this object";
+  if (! (obj->version == 0 || obj->version == 1))
+    return "Integer out of bounds";
+  if (TRUNNEL_DYNARRAY_LEN(&obj->data) != obj->data_len)
+    return "Length mismatch for data";
+  return NULL;
+}
+
+ssize_t
+sendme_cell_encoded_len(const sendme_cell_t *obj)
+{
+  ssize_t result = 0;
+
+  if (NULL != sendme_cell_check(obj))
+     return -1;
+
+
+  /* Length of u8 version IN [0, 1] */
+  result += 1;
+
+  /* Length of u16 data_len */
+  result += 2;
+
+  /* Length of u8 data[data_len] */
+  result += TRUNNEL_DYNARRAY_LEN(&obj->data);
+  return result;
+}
+int
+sendme_cell_clear_errors(sendme_cell_t *obj)
+{
+  int r = obj->trunnel_error_code_;
+  obj->trunnel_error_code_ = 0;
+  return r;
+}
+ssize_t
+sendme_cell_encode(uint8_t *output, const size_t avail, const sendme_cell_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 = sendme_cell_encoded_len(obj);
+#endif
+
+  if (NULL != (msg = sendme_cell_check(obj)))
+    goto check_failed;
+
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+  trunnel_assert(encoded_len >= 0);
+#endif
+
+  /* Encode u8 version IN [0, 1] */
+  trunnel_assert(written <= avail);
+  if (avail - written < 1)
+    goto truncated;
+  trunnel_set_uint8(ptr, (obj->version));
+  written += 1; ptr += 1;
+
+  /* Encode u16 data_len */
+  trunnel_assert(written <= avail);
+  if (avail - written < 2)
+    goto truncated;
+  trunnel_set_uint16(ptr, trunnel_htons(obj->data_len));
+  written += 2; ptr += 2;
+
+  /* Encode u8 data[data_len] */
+  {
+    size_t elt_len = TRUNNEL_DYNARRAY_LEN(&obj->data);
+    trunnel_assert(obj->data_len == elt_len);
+    trunnel_assert(written <= avail);
+    if (avail - written < elt_len)
+      goto truncated;
+    if (elt_len)
+      memcpy(ptr, obj->data.elts_, elt_len);
+    written += elt_len; ptr += elt_len;
+  }
+
+
+  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 sendme_cell_parse(), but do not allocate the output object.
+ */
+static ssize_t
+sendme_cell_parse_into(sendme_cell_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 version IN [0, 1] */
+  CHECK_REMAINING(1, truncated);
+  obj->version = (trunnel_get_uint8(ptr));
+  remaining -= 1; ptr += 1;
+  if (! (obj->version == 0 || obj->version == 1))
+    goto fail;
+
+  /* Parse u16 data_len */
+  CHECK_REMAINING(2, truncated);
+  obj->data_len = trunnel_ntohs(trunnel_get_uint16(ptr));
+  remaining -= 2; ptr += 2;
+
+  /* Parse u8 data[data_len] */
+  CHECK_REMAINING(obj->data_len, truncated);
+  TRUNNEL_DYNARRAY_EXPAND(uint8_t, &obj->data, obj->data_len, {});
+  obj->data.n_ = obj->data_len;
+  if (obj->data_len)
+    memcpy(obj->data.elts_, ptr, obj->data_len);
+  ptr += obj->data_len; remaining -= obj->data_len;
+  trunnel_assert(ptr + remaining == input + len_in);
+  return len_in - remaining;
+
+ truncated:
+  return -2;
+ trunnel_alloc_failed:
+  return -1;
+ fail:
+  result = -1;
+  return result;
+}
+
+ssize_t
+sendme_cell_parse(sendme_cell_t **output, const uint8_t *input, const size_t len_in)
+{
+  ssize_t result;
+  *output = sendme_cell_new();
+  if (NULL == *output)
+    return -1;
+  result = sendme_cell_parse_into(*output, input, len_in);
+  if (result < 0) {
+    sendme_cell_free(*output);
+    *output = NULL;
+  }
+  return result;
+}
+sendme_data_v1_t *
+sendme_data_v1_new(void)
+{
+  sendme_data_v1_t *val = trunnel_calloc(1, sizeof(sendme_data_v1_t));
+  if (NULL == val)
+    return NULL;
+  return val;
+}
+
+/** Release all storage held inside 'obj', but do not free 'obj'.
+ */
+static void
+sendme_data_v1_clear(sendme_data_v1_t *obj)
+{
+  (void) obj;
+}
+
+void
+sendme_data_v1_free(sendme_data_v1_t *obj)
+{
+  if (obj == NULL)
+    return;
+  sendme_data_v1_clear(obj);
+  trunnel_memwipe(obj, sizeof(sendme_data_v1_t));
+  trunnel_free_(obj);
+}
+
+size_t
+sendme_data_v1_getlen_digest(const sendme_data_v1_t *inp)
+{
+  (void)inp;  return 4;
+}
+
+uint8_t
+sendme_data_v1_get_digest(sendme_data_v1_t *inp, size_t idx)
+{
+  trunnel_assert(idx < 4);
+  return inp->digest[idx];
+}
+
+uint8_t
+sendme_data_v1_getconst_digest(const sendme_data_v1_t *inp, size_t idx)
+{
+  return sendme_data_v1_get_digest((sendme_data_v1_t*)inp, idx);
+}
+int
+sendme_data_v1_set_digest(sendme_data_v1_t *inp, size_t idx, uint8_t elt)
+{
+  trunnel_assert(idx < 4);
+  inp->digest[idx] = elt;
+  return 0;
+}
+
+uint8_t *
+sendme_data_v1_getarray_digest(sendme_data_v1_t *inp)
+{
+  return inp->digest;
+}
+const uint8_t  *
+sendme_data_v1_getconstarray_digest(const sendme_data_v1_t *inp)
+{
+  return (const uint8_t  *)sendme_data_v1_getarray_digest((sendme_data_v1_t*)inp);
+}
+const char *
+sendme_data_v1_check(const sendme_data_v1_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
+sendme_data_v1_encoded_len(const sendme_data_v1_t *obj)
+{
+  ssize_t result = 0;
+
+  if (NULL != sendme_data_v1_check(obj))
+     return -1;
+
+
+  /* Length of u8 digest[4] */
+  result += 4;
+  return result;
+}
+int
+sendme_data_v1_clear_errors(sendme_data_v1_t *obj)
+{
+  int r = obj->trunnel_error_code_;
+  obj->trunnel_error_code_ = 0;
+  return r;
+}
+ssize_t
+sendme_data_v1_encode(uint8_t *output, const size_t avail, const sendme_data_v1_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 = sendme_data_v1_encoded_len(obj);
+#endif
+
+  if (NULL != (msg = sendme_data_v1_check(obj)))
+    goto check_failed;
+
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+  trunnel_assert(encoded_len >= 0);
+#endif
+
+  /* Encode u8 digest[4] */
+  trunnel_assert(written <= avail);
+  if (avail - written < 4)
+    goto truncated;
+  memcpy(ptr, obj->digest, 4);
+  written += 4; ptr += 4;
+
+
+  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 sendme_data_v1_parse(), but do not allocate the output object.
+ */
+static ssize_t
+sendme_data_v1_parse_into(sendme_data_v1_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 digest[4] */
+  CHECK_REMAINING(4, truncated);
+  memcpy(obj->digest, ptr, 4);
+  remaining -= 4; ptr += 4;
+  trunnel_assert(ptr + remaining == input + len_in);
+  return len_in - remaining;
+
+ truncated:
+  return -2;
+}
+
+ssize_t
+sendme_data_v1_parse(sendme_data_v1_t **output, const uint8_t *input, const size_t len_in)
+{
+  ssize_t result;
+  *output = sendme_data_v1_new();
+  if (NULL == *output)
+    return -1;
+  result = sendme_data_v1_parse_into(*output, input, len_in);
+  if (result < 0) {
+    sendme_data_v1_free(*output);
+    *output = NULL;
+  }
+  return result;
+}
diff --git a/src/trunnel/sendme.h b/src/trunnel/sendme.h
new file mode 100644
index 0000000000..8207cb56f7
--- /dev/null
+++ b/src/trunnel/sendme.h
@@ -0,0 +1,170 @@
+/* sendme.h -- generated by Trunnel v1.5.2.
+ * https://gitweb.torproject.org/trunnel.git
+ * You probably shouldn't edit this file.
+ */
+#ifndef TRUNNEL_SENDME_H
+#define TRUNNEL_SENDME_H
+
+#include <stdint.h>
+#include "trunnel.h"
+
+#if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_SENDME_CELL)
+struct sendme_cell_st {
+  uint8_t version;
+  uint16_t data_len;
+  TRUNNEL_DYNARRAY_HEAD(, uint8_t) data;
+  uint8_t trunnel_error_code_;
+};
+#endif
+typedef struct sendme_cell_st sendme_cell_t;
+#if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_SENDME_DATA_V1)
+struct sendme_data_v1_st {
+  uint8_t digest[4];
+  uint8_t trunnel_error_code_;
+};
+#endif
+typedef struct sendme_data_v1_st sendme_data_v1_t;
+/** Return a newly allocated sendme_cell with all elements set to
+ * zero.
+ */
+sendme_cell_t *sendme_cell_new(void);
+/** Release all storage held by the sendme_cell in 'victim'. (Do
+ * nothing if 'victim' is NULL.)
+ */
+void sendme_cell_free(sendme_cell_t *victim);
+/** Try to parse a sendme_cell 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
+ * sendme_cell_t. On failure, return -2 if the input appears
+ * truncated, and -1 if the input is otherwise invalid.
+ */
+ssize_t sendme_cell_parse(sendme_cell_t **output, const uint8_t *input, const size_t len_in);
+/** Return the number of bytes we expect to need to encode the
+ * sendme_cell 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 sendme_cell_encoded_len(const sendme_cell_t *obj);
+/** Try to encode the sendme_cell 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 sendme_cell_encode(uint8_t *output, size_t avail, const sendme_cell_t *input);
+/** Check whether the internal state of the sendme_cell in 'obj' is
+ * consistent. Return NULL if it is, and a short message if it is not.
+ */
+const char *sendme_cell_check(const sendme_cell_t *obj);
+/** Clear any errors that were set on the object 'obj' by its setter
+ * functions. Return true iff errors were cleared.
+ */
+int sendme_cell_clear_errors(sendme_cell_t *obj);
+/** Return the value of the version field of the sendme_cell_t in
+ * 'inp'
+ */
+uint8_t sendme_cell_get_version(const sendme_cell_t *inp);
+/** Set the value of the version field of the sendme_cell_t in 'inp'
+ * to 'val'. Return 0 on success; return -1 and set the error code on
+ * 'inp' on failure.
+ */
+int sendme_cell_set_version(sendme_cell_t *inp, uint8_t val);
+/** Return the value of the data_len field of the sendme_cell_t in
+ * 'inp'
+ */
+uint16_t sendme_cell_get_data_len(const sendme_cell_t *inp);
+/** Set the value of the data_len field of the sendme_cell_t in 'inp'
+ * to 'val'. Return 0 on success; return -1 and set the error code on
+ * 'inp' on failure.
+ */
+int sendme_cell_set_data_len(sendme_cell_t *inp, uint16_t val);
+/** Return the length of the dynamic array holding the data field of
+ * the sendme_cell_t in 'inp'.
+ */
+size_t sendme_cell_getlen_data(const sendme_cell_t *inp);
+/** Return the element at position 'idx' of the dynamic array field
+ * data of the sendme_cell_t in 'inp'.
+ */
+uint8_t sendme_cell_get_data(sendme_cell_t *inp, size_t idx);
+/** As sendme_cell_get_data, but take and return a const pointer
+ */
+uint8_t sendme_cell_getconst_data(const sendme_cell_t *inp, size_t idx);
+/** Change the element at position 'idx' of the dynamic array field
+ * data of the sendme_cell_t in 'inp', so that it will hold the value
+ * 'elt'.
+ */
+int sendme_cell_set_data(sendme_cell_t *inp, size_t idx, uint8_t elt);
+/** Append a new element 'elt' to the dynamic array field data of the
+ * sendme_cell_t in 'inp'.
+ */
+int sendme_cell_add_data(sendme_cell_t *inp, uint8_t elt);
+/** Return a pointer to the variable-length array field data of 'inp'.
+ */
+uint8_t * sendme_cell_getarray_data(sendme_cell_t *inp);
+/** As sendme_cell_get_data, but take and return a const pointer
+ */
+const uint8_t  * sendme_cell_getconstarray_data(const sendme_cell_t *inp);
+/** Change the length of the variable-length array field data of 'inp'
+ * to 'newlen'.Fill extra elements with 0. Return 0 on success; return
+ * -1 and set the error code on 'inp' on failure.
+ */
+int sendme_cell_setlen_data(sendme_cell_t *inp, size_t newlen);
+/** Return a newly allocated sendme_data_v1 with all elements set to
+ * zero.
+ */
+sendme_data_v1_t *sendme_data_v1_new(void);
+/** Release all storage held by the sendme_data_v1 in 'victim'. (Do
+ * nothing if 'victim' is NULL.)
+ */
+void sendme_data_v1_free(sendme_data_v1_t *victim);
+/** Try to parse a sendme_data_v1 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
+ * sendme_data_v1_t. On failure, return -2 if the input appears
+ * truncated, and -1 if the input is otherwise invalid.
+ */
+ssize_t sendme_data_v1_parse(sendme_data_v1_t **output, const uint8_t *input, const size_t len_in);
+/** Return the number of bytes we expect to need to encode the
+ * sendme_data_v1 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 sendme_data_v1_encoded_len(const sendme_data_v1_t *obj);
+/** Try to encode the sendme_data_v1 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 sendme_data_v1_encode(uint8_t *output, size_t avail, const sendme_data_v1_t *input);
+/** Check whether the internal state of the sendme_data_v1 in 'obj' is
+ * consistent. Return NULL if it is, and a short message if it is not.
+ */
+const char *sendme_data_v1_check(const sendme_data_v1_t *obj);
+/** Clear any errors that were set on the object 'obj' by its setter
+ * functions. Return true iff errors were cleared.
+ */
+int sendme_data_v1_clear_errors(sendme_data_v1_t *obj);
+/** Return the (constant) length of the array holding the digest field
+ * of the sendme_data_v1_t in 'inp'.
+ */
+size_t sendme_data_v1_getlen_digest(const sendme_data_v1_t *inp);
+/** Return the element at position 'idx' of the fixed array field
+ * digest of the sendme_data_v1_t in 'inp'.
+ */
+uint8_t sendme_data_v1_get_digest(sendme_data_v1_t *inp, size_t idx);
+/** As sendme_data_v1_get_digest, but take and return a const pointer
+ */
+uint8_t sendme_data_v1_getconst_digest(const sendme_data_v1_t *inp, size_t idx);
+/** Change the element at position 'idx' of the fixed array field
+ * digest of the sendme_data_v1_t in 'inp', so that it will hold the
+ * value 'elt'.
+ */
+int sendme_data_v1_set_digest(sendme_data_v1_t *inp, size_t idx, uint8_t elt);
+/** Return a pointer to the 4-element array field digest of 'inp'.
+ */
+uint8_t * sendme_data_v1_getarray_digest(sendme_data_v1_t *inp);
+/** As sendme_data_v1_get_digest, but take and return a const pointer
+ */
+const uint8_t  * sendme_data_v1_getconstarray_digest(const sendme_data_v1_t *inp);
+
+
+#endif
diff --git a/src/trunnel/sendme.trunnel b/src/trunnel/sendme.trunnel
new file mode 100644
index 0000000000..7294a09b47
--- /dev/null
+++ b/src/trunnel/sendme.trunnel
@@ -0,0 +1,18 @@
+/* This file contains the SENDME cell definition. */
+
+struct sendme_cell {
+  /* Version field. */
+  u8 version IN [0x00, 0x01];
+
+  /* The data content depends on the version. */
+  u16 data_len;
+  u8 data[data_len];
+}
+
+/* SENDME version 0. No data. */
+
+/* SENDME version 1. Authenticated with digest. */
+struct sendme_data_v1 {
+  /* A 4 bytes digest. */
+  u8 digest[4];
+}