From 5ef811b7d0a1c5352b5c6ff202f65001db36086f Mon Sep 17 00:00:00 2001
From: David Goulet <dgoulet@torproject.org>
Date: Mon, 27 Jun 2022 13:41:35 -0400
Subject: [PATCH] trunnel: INTRODUCE1 PoW cell extension

Signed-off-by: David Goulet <dgoulet@torproject.org>
---
 src/trunnel/hs/cell_introduce1.c       | 319 +++++++++++++++++++++++++
 src/trunnel/hs/cell_introduce1.h       | 128 ++++++++++
 src/trunnel/hs/cell_introduce1.trunnel |  33 +++
 3 files changed, 480 insertions(+)

diff --git a/src/trunnel/hs/cell_introduce1.c b/src/trunnel/hs/cell_introduce1.c
index a6873b4199..03943568e7 100644
--- a/src/trunnel/hs/cell_introduce1.c
+++ b/src/trunnel/hs/cell_introduce1.c
@@ -44,6 +44,325 @@ ssize_t link_specifier_encoded_len(const link_specifier_t *obj);
 ssize_t link_specifier_encode(uint8_t *output, size_t avail, const link_specifier_t *input);
 const char *link_specifier_check(const link_specifier_t *obj);
 int link_specifier_clear_errors(link_specifier_t *obj);
+trn_cell_extension_pow_t *
+trn_cell_extension_pow_new(void)
+{
+  trn_cell_extension_pow_t *val = trunnel_calloc(1, sizeof(trn_cell_extension_pow_t));
+  if (NULL == val)
+    return NULL;
+  val->pow_version = 1;
+  return val;
+}
+
+/** Release all storage held inside 'obj', but do not free 'obj'.
+ */
+static void
+trn_cell_extension_pow_clear(trn_cell_extension_pow_t *obj)
+{
+  (void) obj;
+}
+
+void
+trn_cell_extension_pow_free(trn_cell_extension_pow_t *obj)
+{
+  if (obj == NULL)
+    return;
+  trn_cell_extension_pow_clear(obj);
+  trunnel_memwipe(obj, sizeof(trn_cell_extension_pow_t));
+  trunnel_free_(obj);
+}
+
+uint8_t
+trn_cell_extension_pow_get_pow_version(const trn_cell_extension_pow_t *inp)
+{
+  return inp->pow_version;
+}
+int
+trn_cell_extension_pow_set_pow_version(trn_cell_extension_pow_t *inp, uint8_t val)
+{
+  if (! ((val == 1))) {
+     TRUNNEL_SET_ERROR_CODE(inp);
+     return -1;
+  }
+  inp->pow_version = val;
+  return 0;
+}
+size_t
+trn_cell_extension_pow_getlen_pow_nonce(const trn_cell_extension_pow_t *inp)
+{
+  (void)inp;  return TRUNNEL_POW_NONCE_LEN;
+}
+
+uint8_t
+trn_cell_extension_pow_get_pow_nonce(trn_cell_extension_pow_t *inp, size_t idx)
+{
+  trunnel_assert(idx < TRUNNEL_POW_NONCE_LEN);
+  return inp->pow_nonce[idx];
+}
+
+uint8_t
+trn_cell_extension_pow_getconst_pow_nonce(const trn_cell_extension_pow_t *inp, size_t idx)
+{
+  return trn_cell_extension_pow_get_pow_nonce((trn_cell_extension_pow_t*)inp, idx);
+}
+int
+trn_cell_extension_pow_set_pow_nonce(trn_cell_extension_pow_t *inp, size_t idx, uint8_t elt)
+{
+  trunnel_assert(idx < TRUNNEL_POW_NONCE_LEN);
+  inp->pow_nonce[idx] = elt;
+  return 0;
+}
+
+uint8_t *
+trn_cell_extension_pow_getarray_pow_nonce(trn_cell_extension_pow_t *inp)
+{
+  return inp->pow_nonce;
+}
+const uint8_t  *
+trn_cell_extension_pow_getconstarray_pow_nonce(const trn_cell_extension_pow_t *inp)
+{
+  return (const uint8_t  *)trn_cell_extension_pow_getarray_pow_nonce((trn_cell_extension_pow_t*)inp);
+}
+uint32_t
+trn_cell_extension_pow_get_pow_effort(const trn_cell_extension_pow_t *inp)
+{
+  return inp->pow_effort;
+}
+int
+trn_cell_extension_pow_set_pow_effort(trn_cell_extension_pow_t *inp, uint32_t val)
+{
+  inp->pow_effort = val;
+  return 0;
+}
+uint32_t
+trn_cell_extension_pow_get_pow_seed(const trn_cell_extension_pow_t *inp)
+{
+  return inp->pow_seed;
+}
+int
+trn_cell_extension_pow_set_pow_seed(trn_cell_extension_pow_t *inp, uint32_t val)
+{
+  inp->pow_seed = val;
+  return 0;
+}
+size_t
+trn_cell_extension_pow_getlen_pow_solution(const trn_cell_extension_pow_t *inp)
+{
+  (void)inp;  return TRUNNEL_POW_SOLUTION_LEN;
+}
+
+uint8_t
+trn_cell_extension_pow_get_pow_solution(trn_cell_extension_pow_t *inp, size_t idx)
+{
+  trunnel_assert(idx < TRUNNEL_POW_SOLUTION_LEN);
+  return inp->pow_solution[idx];
+}
+
+uint8_t
+trn_cell_extension_pow_getconst_pow_solution(const trn_cell_extension_pow_t *inp, size_t idx)
+{
+  return trn_cell_extension_pow_get_pow_solution((trn_cell_extension_pow_t*)inp, idx);
+}
+int
+trn_cell_extension_pow_set_pow_solution(trn_cell_extension_pow_t *inp, size_t idx, uint8_t elt)
+{
+  trunnel_assert(idx < TRUNNEL_POW_SOLUTION_LEN);
+  inp->pow_solution[idx] = elt;
+  return 0;
+}
+
+uint8_t *
+trn_cell_extension_pow_getarray_pow_solution(trn_cell_extension_pow_t *inp)
+{
+  return inp->pow_solution;
+}
+const uint8_t  *
+trn_cell_extension_pow_getconstarray_pow_solution(const trn_cell_extension_pow_t *inp)
+{
+  return (const uint8_t  *)trn_cell_extension_pow_getarray_pow_solution((trn_cell_extension_pow_t*)inp);
+}
+const char *
+trn_cell_extension_pow_check(const trn_cell_extension_pow_t *obj)
+{
+  if (obj == NULL)
+    return "Object was NULL";
+  if (obj->trunnel_error_code_)
+    return "A set function failed on this object";
+  if (! (obj->pow_version == 1))
+    return "Integer out of bounds";
+  return NULL;
+}
+
+ssize_t
+trn_cell_extension_pow_encoded_len(const trn_cell_extension_pow_t *obj)
+{
+  ssize_t result = 0;
+
+  if (NULL != trn_cell_extension_pow_check(obj))
+     return -1;
+
+
+  /* Length of u8 pow_version IN [1] */
+  result += 1;
+
+  /* Length of u8 pow_nonce[TRUNNEL_POW_NONCE_LEN] */
+  result += TRUNNEL_POW_NONCE_LEN;
+
+  /* Length of u32 pow_effort */
+  result += 4;
+
+  /* Length of u32 pow_seed */
+  result += 4;
+
+  /* Length of u8 pow_solution[TRUNNEL_POW_SOLUTION_LEN] */
+  result += TRUNNEL_POW_SOLUTION_LEN;
+  return result;
+}
+int
+trn_cell_extension_pow_clear_errors(trn_cell_extension_pow_t *obj)
+{
+  int r = obj->trunnel_error_code_;
+  obj->trunnel_error_code_ = 0;
+  return r;
+}
+ssize_t
+trn_cell_extension_pow_encode(uint8_t *output, const size_t avail, const trn_cell_extension_pow_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_pow_encoded_len(obj);
+#endif
+
+  if (NULL != (msg = trn_cell_extension_pow_check(obj)))
+    goto check_failed;
+
+#ifdef TRUNNEL_CHECK_ENCODED_LEN
+  trunnel_assert(encoded_len >= 0);
+#endif
+
+  /* Encode u8 pow_version IN [1] */
+  trunnel_assert(written <= avail);
+  if (avail - written < 1)
+    goto truncated;
+  trunnel_set_uint8(ptr, (obj->pow_version));
+  written += 1; ptr += 1;
+
+  /* Encode u8 pow_nonce[TRUNNEL_POW_NONCE_LEN] */
+  trunnel_assert(written <= avail);
+  if (avail - written < TRUNNEL_POW_NONCE_LEN)
+    goto truncated;
+  memcpy(ptr, obj->pow_nonce, TRUNNEL_POW_NONCE_LEN);
+  written += TRUNNEL_POW_NONCE_LEN; ptr += TRUNNEL_POW_NONCE_LEN;
+
+  /* Encode u32 pow_effort */
+  trunnel_assert(written <= avail);
+  if (avail - written < 4)
+    goto truncated;
+  trunnel_set_uint32(ptr, trunnel_htonl(obj->pow_effort));
+  written += 4; ptr += 4;
+
+  /* Encode u32 pow_seed */
+  trunnel_assert(written <= avail);
+  if (avail - written < 4)
+    goto truncated;
+  trunnel_set_uint32(ptr, trunnel_htonl(obj->pow_seed));
+  written += 4; ptr += 4;
+
+  /* Encode u8 pow_solution[TRUNNEL_POW_SOLUTION_LEN] */
+  trunnel_assert(written <= avail);
+  if (avail - written < TRUNNEL_POW_SOLUTION_LEN)
+    goto truncated;
+  memcpy(ptr, obj->pow_solution, TRUNNEL_POW_SOLUTION_LEN);
+  written += TRUNNEL_POW_SOLUTION_LEN; ptr += TRUNNEL_POW_SOLUTION_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 trn_cell_extension_pow_parse(), but do not allocate the output
+ * object.
+ */
+static ssize_t
+trn_cell_extension_pow_parse_into(trn_cell_extension_pow_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 pow_version IN [1] */
+  CHECK_REMAINING(1, truncated);
+  obj->pow_version = (trunnel_get_uint8(ptr));
+  remaining -= 1; ptr += 1;
+  if (! (obj->pow_version == 1))
+    goto fail;
+
+  /* Parse u8 pow_nonce[TRUNNEL_POW_NONCE_LEN] */
+  CHECK_REMAINING(TRUNNEL_POW_NONCE_LEN, truncated);
+  memcpy(obj->pow_nonce, ptr, TRUNNEL_POW_NONCE_LEN);
+  remaining -= TRUNNEL_POW_NONCE_LEN; ptr += TRUNNEL_POW_NONCE_LEN;
+
+  /* Parse u32 pow_effort */
+  CHECK_REMAINING(4, truncated);
+  obj->pow_effort = trunnel_ntohl(trunnel_get_uint32(ptr));
+  remaining -= 4; ptr += 4;
+
+  /* Parse u32 pow_seed */
+  CHECK_REMAINING(4, truncated);
+  obj->pow_seed = trunnel_ntohl(trunnel_get_uint32(ptr));
+  remaining -= 4; ptr += 4;
+
+  /* Parse u8 pow_solution[TRUNNEL_POW_SOLUTION_LEN] */
+  CHECK_REMAINING(TRUNNEL_POW_SOLUTION_LEN, truncated);
+  memcpy(obj->pow_solution, ptr, TRUNNEL_POW_SOLUTION_LEN);
+  remaining -= TRUNNEL_POW_SOLUTION_LEN; ptr += TRUNNEL_POW_SOLUTION_LEN;
+  trunnel_assert(ptr + remaining == input + len_in);
+  return len_in - remaining;
+
+ truncated:
+  return -2;
+ fail:
+  result = -1;
+  return result;
+}
+
+ssize_t
+trn_cell_extension_pow_parse(trn_cell_extension_pow_t **output, const uint8_t *input, const size_t len_in)
+{
+  ssize_t result;
+  *output = trn_cell_extension_pow_new();
+  if (NULL == *output)
+    return -1;
+  result = trn_cell_extension_pow_parse_into(*output, input, len_in);
+  if (result < 0) {
+    trn_cell_extension_pow_free(*output);
+    *output = NULL;
+  }
+  return result;
+}
 trn_cell_introduce1_t *
 trn_cell_introduce1_new(void)
 {
diff --git a/src/trunnel/hs/cell_introduce1.h b/src/trunnel/hs/cell_introduce1.h
index ea37502d8e..89339e1a0d 100644
--- a/src/trunnel/hs/cell_introduce1.h
+++ b/src/trunnel/hs/cell_introduce1.h
@@ -19,6 +19,21 @@ struct link_specifier_st;
 #define TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_LEGACY1 1
 #define TRUNNEL_HS_INTRO_AUTH_KEY_TYPE_ED25519 2
 #define TRUNNEL_HS_INTRO_ONION_KEY_TYPE_NTOR 1
+#define TRUNNEL_CELL_EXTENSION_TYPE_POW 1
+#define TRUNNEL_POW_NONCE_LEN 16
+#define TRUNNEL_POW_SOLUTION_LEN 16
+#define TRUNNEL_POW_EQUIX 1
+#if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_TRN_CELL_EXTENSION_POW)
+struct trn_cell_extension_pow_st {
+  uint8_t pow_version;
+  uint8_t pow_nonce[TRUNNEL_POW_NONCE_LEN];
+  uint32_t pow_effort;
+  uint32_t pow_seed;
+  uint8_t pow_solution[TRUNNEL_POW_SOLUTION_LEN];
+  uint8_t trunnel_error_code_;
+};
+#endif
+typedef struct trn_cell_extension_pow_st trn_cell_extension_pow_t;
 #if !defined(TRUNNEL_OPAQUE) && !defined(TRUNNEL_OPAQUE_TRN_CELL_INTRODUCE1)
 struct trn_cell_introduce1_st {
   uint8_t legacy_key_id[TRUNNEL_SHA1_LEN];
@@ -53,6 +68,119 @@ struct trn_cell_introduce_encrypted_st {
 };
 #endif
 typedef struct trn_cell_introduce_encrypted_st trn_cell_introduce_encrypted_t;
+/** Return a newly allocated trn_cell_extension_pow with all elements
+ * set to zero.
+ */
+trn_cell_extension_pow_t *trn_cell_extension_pow_new(void);
+/** Release all storage held by the trn_cell_extension_pow in
+ * 'victim'. (Do nothing if 'victim' is NULL.)
+ */
+void trn_cell_extension_pow_free(trn_cell_extension_pow_t *victim);
+/** Try to parse a trn_cell_extension_pow 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_pow_t. On failure, return -2 if the
+ * input appears truncated, and -1 if the input is otherwise invalid.
+ */
+ssize_t trn_cell_extension_pow_parse(trn_cell_extension_pow_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_pow 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_pow_encoded_len(const trn_cell_extension_pow_t *obj);
+/** Try to encode the trn_cell_extension_pow 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_pow_encode(uint8_t *output, size_t avail, const trn_cell_extension_pow_t *input);
+/** Check whether the internal state of the trn_cell_extension_pow in
+ * 'obj' is consistent. Return NULL if it is, and a short message if
+ * it is not.
+ */
+const char *trn_cell_extension_pow_check(const trn_cell_extension_pow_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_pow_clear_errors(trn_cell_extension_pow_t *obj);
+/** Return the value of the pow_version field of the
+ * trn_cell_extension_pow_t in 'inp'
+ */
+uint8_t trn_cell_extension_pow_get_pow_version(const trn_cell_extension_pow_t *inp);
+/** Set the value of the pow_version field of the
+ * trn_cell_extension_pow_t in 'inp' to 'val'. Return 0 on success;
+ * return -1 and set the error code on 'inp' on failure.
+ */
+int trn_cell_extension_pow_set_pow_version(trn_cell_extension_pow_t *inp, uint8_t val);
+/** Return the (constant) length of the array holding the pow_nonce
+ * field of the trn_cell_extension_pow_t in 'inp'.
+ */
+size_t trn_cell_extension_pow_getlen_pow_nonce(const trn_cell_extension_pow_t *inp);
+/** Return the element at position 'idx' of the fixed array field
+ * pow_nonce of the trn_cell_extension_pow_t in 'inp'.
+ */
+uint8_t trn_cell_extension_pow_get_pow_nonce(trn_cell_extension_pow_t *inp, size_t idx);
+/** As trn_cell_extension_pow_get_pow_nonce, but take and return a
+ * const pointer
+ */
+uint8_t trn_cell_extension_pow_getconst_pow_nonce(const trn_cell_extension_pow_t *inp, size_t idx);
+/** Change the element at position 'idx' of the fixed array field
+ * pow_nonce of the trn_cell_extension_pow_t in 'inp', so that it will
+ * hold the value 'elt'.
+ */
+int trn_cell_extension_pow_set_pow_nonce(trn_cell_extension_pow_t *inp, size_t idx, uint8_t elt);
+/** Return a pointer to the TRUNNEL_POW_NONCE_LEN-element array field
+ * pow_nonce of 'inp'.
+ */
+uint8_t * trn_cell_extension_pow_getarray_pow_nonce(trn_cell_extension_pow_t *inp);
+/** As trn_cell_extension_pow_get_pow_nonce, but take and return a
+ * const pointer
+ */
+const uint8_t  * trn_cell_extension_pow_getconstarray_pow_nonce(const trn_cell_extension_pow_t *inp);
+/** Return the value of the pow_effort field of the
+ * trn_cell_extension_pow_t in 'inp'
+ */
+uint32_t trn_cell_extension_pow_get_pow_effort(const trn_cell_extension_pow_t *inp);
+/** Set the value of the pow_effort field of the
+ * trn_cell_extension_pow_t in 'inp' to 'val'. Return 0 on success;
+ * return -1 and set the error code on 'inp' on failure.
+ */
+int trn_cell_extension_pow_set_pow_effort(trn_cell_extension_pow_t *inp, uint32_t val);
+/** Return the value of the pow_seed field of the
+ * trn_cell_extension_pow_t in 'inp'
+ */
+uint32_t trn_cell_extension_pow_get_pow_seed(const trn_cell_extension_pow_t *inp);
+/** Set the value of the pow_seed field of the
+ * trn_cell_extension_pow_t in 'inp' to 'val'. Return 0 on success;
+ * return -1 and set the error code on 'inp' on failure.
+ */
+int trn_cell_extension_pow_set_pow_seed(trn_cell_extension_pow_t *inp, uint32_t val);
+/** Return the (constant) length of the array holding the pow_solution
+ * field of the trn_cell_extension_pow_t in 'inp'.
+ */
+size_t trn_cell_extension_pow_getlen_pow_solution(const trn_cell_extension_pow_t *inp);
+/** Return the element at position 'idx' of the fixed array field
+ * pow_solution of the trn_cell_extension_pow_t in 'inp'.
+ */
+uint8_t trn_cell_extension_pow_get_pow_solution(trn_cell_extension_pow_t *inp, size_t idx);
+/** As trn_cell_extension_pow_get_pow_solution, but take and return a
+ * const pointer
+ */
+uint8_t trn_cell_extension_pow_getconst_pow_solution(const trn_cell_extension_pow_t *inp, size_t idx);
+/** Change the element at position 'idx' of the fixed array field
+ * pow_solution of the trn_cell_extension_pow_t in 'inp', so that it
+ * will hold the value 'elt'.
+ */
+int trn_cell_extension_pow_set_pow_solution(trn_cell_extension_pow_t *inp, size_t idx, uint8_t elt);
+/** Return a pointer to the TRUNNEL_POW_SOLUTION_LEN-element array
+ * field pow_solution of 'inp'.
+ */
+uint8_t * trn_cell_extension_pow_getarray_pow_solution(trn_cell_extension_pow_t *inp);
+/** As trn_cell_extension_pow_get_pow_solution, but take and return a
+ * const pointer
+ */
+const uint8_t  * trn_cell_extension_pow_getconstarray_pow_solution(const trn_cell_extension_pow_t *inp);
 /** Return a newly allocated trn_cell_introduce1 with all elements set
  * to zero.
  */
diff --git a/src/trunnel/hs/cell_introduce1.trunnel b/src/trunnel/hs/cell_introduce1.trunnel
index 6682227b44..18865ddc02 100644
--- a/src/trunnel/hs/cell_introduce1.trunnel
+++ b/src/trunnel/hs/cell_introduce1.trunnel
@@ -73,3 +73,36 @@ struct trn_cell_introduce_encrypted {
   /* Optional padding. This might be empty or not. */
   u8 pad[];
 };
+
+/*
+ * INTRODUCE1 cell (encrypted section) extensions.
+ */
+
+/* Cell extension type PoW. */
+const TRUNNEL_CELL_EXTENSION_TYPE_POW = 0x01;
+
+/*
+ * HRPR: PoW Solution Extension. Proposal 327.
+ */
+
+const TRUNNEL_POW_NONCE_LEN = 16;
+const TRUNNEL_POW_SOLUTION_LEN = 16;
+/* Version 1 is based on Equi-X scheme. */
+const TRUNNEL_POW_EQUIX = 0x01;
+
+struct trn_cell_extension_pow {
+  /* Type of PoW system used. */
+  u8 pow_version IN [0x01];
+
+  /* Nonce */
+  u8 pow_nonce[TRUNNEL_POW_NONCE_LEN];
+
+  /* Effort */
+  u32 pow_effort;
+
+  /* First 4 bytes of the seed. */
+  u32 pow_seed;
+
+  /* Solution. */
+  u8 pow_solution[TRUNNEL_POW_SOLUTION_LEN];
+};