Move v2 hs parsing into feature/rend

5 files changed, 635 insertions, 0 deletions

diff --git a/src/feature/rend/rendcache.c b/src/feature/rend/rendcache.c
index 9197a53bda..4c8afbfca4 100644
--- a/src/feature/rend/rendcache.c
+++ b/src/feature/rend/rendcache.c
@@ -14,6 +14,7 @@
 #include "feature/nodelist/routerlist.h"
 #include "feature/dirparse/routerparse.h"
 #include "feature/rend/rendcommon.h"
+#include "feature/rend/rendparse.h"
 
 #include "core/or/extend_info_st.h"
 #include "feature/rend/rend_intro_point_st.h"
diff --git a/src/feature/rend/rendcommon.c b/src/feature/rend/rendcommon.c
index 2c28437b27..458b92f510 100644
--- a/src/feature/rend/rendcommon.c
+++ b/src/feature/rend/rendcommon.c
@@ -25,6 +25,7 @@
 #include "feature/rend/rendclient.h"
 #include "feature/rend/rendcommon.h"
 #include "feature/rend/rendmid.h"
+#include "feature/rend/rendparse.h"
 #include "feature/rend/rendservice.h"
 #include "feature/stats/rephist.h"
 #include "feature/hs_common/replaycache.h"
diff --git a/src/feature/rend/rendparse.c b/src/feature/rend/rendparse.c
new file mode 100644
index 0000000000..e2378e340f
--- /dev/null
+++ b/src/feature/rend/rendparse.c
@@ -0,0 +1,600 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file rendparse.c
+ * \brief Code to parse and validate v2 hidden service descriptors.
+ **/
+
+#include "core/or/or.h"
+#include "feature/dirparse/parsecommon.h"
+#include "feature/dirparse/sigcommon.h"
+#include "feature/rend/rendcommon.h"
+#include "feature/rend/rendparse.h"
+#include "lib/memarea/memarea.h"
+
+#include "core/or/extend_info_st.h"
+#include "feature/rend/rend_authorized_client_st.h"
+#include "feature/rend/rend_intro_point_st.h"
+#include "feature/rend/rend_service_descriptor_st.h"
+
+/** List of tokens recognized in rendezvous service descriptors */
+static token_rule_t desc_token_table[] = {
+  T1_START("rendezvous-service-descriptor", R_RENDEZVOUS_SERVICE_DESCRIPTOR,
+           EQ(1), NO_OBJ),
+  T1("version", R_VERSION, EQ(1), NO_OBJ),
+  T1("permanent-key", R_PERMANENT_KEY, NO_ARGS, NEED_KEY_1024),
+  T1("secret-id-part", R_SECRET_ID_PART, EQ(1), NO_OBJ),
+  T1("publication-time", R_PUBLICATION_TIME, CONCAT_ARGS, NO_OBJ),
+  T1("protocol-versions", R_PROTOCOL_VERSIONS, EQ(1), NO_OBJ),
+  T01("introduction-points", R_INTRODUCTION_POINTS, NO_ARGS, NEED_OBJ),
+  T1_END("signature", R_SIGNATURE, NO_ARGS, NEED_OBJ),
+  END_OF_TABLE
+};
+
+/** List of tokens recognized in the (encrypted) list of introduction points of
+ * rendezvous service descriptors */
+static token_rule_t ipo_token_table[] = {
+  T1_START("introduction-point", R_IPO_IDENTIFIER, EQ(1), NO_OBJ),
+  T1("ip-address", R_IPO_IP_ADDRESS, EQ(1), NO_OBJ),
+  T1("onion-port", R_IPO_ONION_PORT, EQ(1), NO_OBJ),
+  T1("onion-key", R_IPO_ONION_KEY, NO_ARGS, NEED_KEY_1024),
+  T1("service-key", R_IPO_SERVICE_KEY, NO_ARGS, NEED_KEY_1024),
+  END_OF_TABLE
+};
+
+/** List of tokens recognized in the (possibly encrypted) list of introduction
+ * points of rendezvous service descriptors */
+static token_rule_t client_keys_token_table[] = {
+  T1_START("client-name", C_CLIENT_NAME, CONCAT_ARGS, NO_OBJ),
+  T1("descriptor-cookie", C_DESCRIPTOR_COOKIE, EQ(1), NO_OBJ),
+  T01("client-key", C_CLIENT_KEY, NO_ARGS, NEED_SKEY_1024),
+  END_OF_TABLE
+};
+
+/** Parse and validate the ASCII-encoded v2 descriptor in <b>desc</b>,
+ * write the parsed descriptor to the newly allocated *<b>parsed_out</b>, the
+ * binary descriptor ID of length DIGEST_LEN to <b>desc_id_out</b>, the
+ * encrypted introduction points to the newly allocated
+ * *<b>intro_points_encrypted_out</b>, their encrypted size to
+ * *<b>intro_points_encrypted_size_out</b>, the size of the encoded descriptor
+ * to *<b>encoded_size_out</b>, and a pointer to the possibly next
+ * descriptor to *<b>next_out</b>; return 0 for success (including validation)
+ * and -1 for failure.
+ *
+ * If <b>as_hsdir</b> is 1, we're parsing this as an HSDir, and we should
+ * be strict about time formats.
+ */
+int
+rend_parse_v2_service_descriptor(rend_service_descriptor_t **parsed_out,
+                                 char *desc_id_out,
+                                 char **intro_points_encrypted_out,
+                                 size_t *intro_points_encrypted_size_out,
+                                 size_t *encoded_size_out,
+                                 const char **next_out, const char *desc,
+                                 int as_hsdir)
+{
+  rend_service_descriptor_t *result =
+                            tor_malloc_zero(sizeof(rend_service_descriptor_t));
+  char desc_hash[DIGEST_LEN];
+  const char *eos;
+  smartlist_t *tokens = smartlist_new();
+  directory_token_t *tok;
+  char secret_id_part[DIGEST_LEN];
+  int i, version, num_ok=1;
+  smartlist_t *versions;
+  char public_key_hash[DIGEST_LEN];
+  char test_desc_id[DIGEST_LEN];
+  memarea_t *area = NULL;
+  const int strict_time_fmt = as_hsdir;
+
+  tor_assert(desc);
+  /* Check if desc starts correctly. */
+  if (strcmpstart(desc, "rendezvous-service-descriptor ")) {
+    log_info(LD_REND, "Descriptor does not start correctly.");
+    goto err;
+  }
+  /* Compute descriptor hash for later validation. */
+  if (router_get_hash_impl(desc, strlen(desc), desc_hash,
+                           "rendezvous-service-descriptor ",
+                           "\nsignature", '\n', DIGEST_SHA1) < 0) {
+    log_warn(LD_REND, "Couldn't compute descriptor hash.");
+    goto err;
+  }
+  /* Determine end of string. */
+  eos = strstr(desc, "\nrendezvous-service-descriptor ");
+  if (!eos)
+    eos = desc + strlen(desc);
+  else
+    eos = eos + 1;
+  /* Check length. */
+  if (eos-desc > REND_DESC_MAX_SIZE) {
+    /* XXXX+ If we are parsing this descriptor as a server, this
+     * should be a protocol warning. */
+    log_warn(LD_REND, "Descriptor length is %d which exceeds "
+             "maximum rendezvous descriptor size of %d bytes.",
+             (int)(eos-desc), REND_DESC_MAX_SIZE);
+    goto err;
+  }
+  /* Tokenize descriptor. */
+  area = memarea_new();
+  if (tokenize_string(area, desc, eos, tokens, desc_token_table, 0)) {
+    log_warn(LD_REND, "Error tokenizing descriptor.");
+    goto err;
+  }
+  /* Set next to next descriptor, if available. */
+  *next_out = eos;
+  /* Set length of encoded descriptor. */
+  *encoded_size_out = eos - desc;
+  /* Check min allowed length of token list. */
+  if (smartlist_len(tokens) < 7) {
+    log_warn(LD_REND, "Impossibly short descriptor.");
+    goto err;
+  }
+  /* Parse base32-encoded descriptor ID. */
+  tok = find_by_keyword(tokens, R_RENDEZVOUS_SERVICE_DESCRIPTOR);
+  tor_assert(tok == smartlist_get(tokens, 0));
+  tor_assert(tok->n_args == 1);
+  if (!rend_valid_descriptor_id(tok->args[0])) {
+    log_warn(LD_REND, "Invalid descriptor ID: '%s'", tok->args[0]);
+    goto err;
+  }
+  if (base32_decode(desc_id_out, DIGEST_LEN,
+                    tok->args[0], REND_DESC_ID_V2_LEN_BASE32) < 0) {
+    log_warn(LD_REND, "Descriptor ID contains illegal characters: %s",
+             tok->args[0]);
+    goto err;
+  }
+  /* Parse descriptor version. */
+  tok = find_by_keyword(tokens, R_VERSION);
+  tor_assert(tok->n_args == 1);
+  result->version =
+    (int) tor_parse_long(tok->args[0], 10, 0, INT_MAX, &num_ok, NULL);
+  if (result->version != 2 || !num_ok) {
+    /* If it's <2, it shouldn't be under this format.  If the number
+     * is greater than 2, we bumped it because we broke backward
+     * compatibility.  See how version numbers in our other formats
+     * work. */
+    log_warn(LD_REND, "Unrecognized descriptor version: %s",
+             escaped(tok->args[0]));
+    goto err;
+  }
+  /* Parse public key. */
+  tok = find_by_keyword(tokens, R_PERMANENT_KEY);
+  result->pk = tok->key;
+  tok->key = NULL; /* Prevent free */
+  /* Parse secret ID part. */
+  tok = find_by_keyword(tokens, R_SECRET_ID_PART);
+  tor_assert(tok->n_args == 1);
+  if (strlen(tok->args[0]) != REND_SECRET_ID_PART_LEN_BASE32 ||
+      strspn(tok->args[0], BASE32_CHARS) != REND_SECRET_ID_PART_LEN_BASE32) {
+    log_warn(LD_REND, "Invalid secret ID part: '%s'", tok->args[0]);
+    goto err;
+  }
+  if (base32_decode(secret_id_part, DIGEST_LEN, tok->args[0], 32) < 0) {
+    log_warn(LD_REND, "Secret ID part contains illegal characters: %s",
+             tok->args[0]);
+    goto err;
+  }
+  /* Parse publication time -- up-to-date check is done when storing the
+   * descriptor. */
+  tok = find_by_keyword(tokens, R_PUBLICATION_TIME);
+  tor_assert(tok->n_args == 1);
+  if (parse_iso_time_(tok->args[0], &result->timestamp,
+                      strict_time_fmt, 0) < 0) {
+    log_warn(LD_REND, "Invalid publication time: '%s'", tok->args[0]);
+    goto err;
+  }
+  /* Parse protocol versions. */
+  tok = find_by_keyword(tokens, R_PROTOCOL_VERSIONS);
+  tor_assert(tok->n_args == 1);
+  versions = smartlist_new();
+  smartlist_split_string(versions, tok->args[0], ",",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  for (i = 0; i < smartlist_len(versions); i++) {
+    version = (int) tor_parse_long(smartlist_get(versions, i),
+                                   10, 0, INT_MAX, &num_ok, NULL);
+    if (!num_ok) /* It's a string; let's ignore it. */
+      continue;
+    if (version >= REND_PROTOCOL_VERSION_BITMASK_WIDTH)
+      /* Avoid undefined left-shift behaviour. */
+      continue;
+    result->protocols |= 1 << version;
+  }
+  SMARTLIST_FOREACH(versions, char *, cp, tor_free(cp));
+  smartlist_free(versions);
+  /* Parse encrypted introduction points. Don't verify. */
+  tok = find_opt_by_keyword(tokens, R_INTRODUCTION_POINTS);
+  if (tok) {
+    if (strcmp(tok->object_type, "MESSAGE")) {
+      log_warn(LD_DIR, "Bad object type: introduction points should be of "
+               "type MESSAGE");
+      goto err;
+    }
+    *intro_points_encrypted_out = tor_memdup(tok->object_body,
+                                             tok->object_size);
+    *intro_points_encrypted_size_out = tok->object_size;
+  } else {
+    *intro_points_encrypted_out = NULL;
+    *intro_points_encrypted_size_out = 0;
+  }
+  /* Parse and verify signature. */
+  tok = find_by_keyword(tokens, R_SIGNATURE);
+  if (check_signature_token(desc_hash, DIGEST_LEN, tok, result->pk, 0,
+                            "v2 rendezvous service descriptor") < 0)
+    goto err;
+  /* Verify that descriptor ID belongs to public key and secret ID part. */
+  if (crypto_pk_get_digest(result->pk, public_key_hash) < 0) {
+    log_warn(LD_REND, "Unable to compute rend descriptor public key digest");
+    goto err;
+  }
+  rend_get_descriptor_id_bytes(test_desc_id, public_key_hash,
+                               secret_id_part);
+  if (tor_memneq(desc_id_out, test_desc_id, DIGEST_LEN)) {
+    log_warn(LD_REND, "Parsed descriptor ID does not match "
+             "computed descriptor ID.");
+    goto err;
+  }
+  goto done;
+ err:
+  rend_service_descriptor_free(result);
+  result = NULL;
+ done:
+  if (tokens) {
+    SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
+    smartlist_free(tokens);
+  }
+  if (area)
+    memarea_drop_all(area);
+  *parsed_out = result;
+  if (result)
+    return 0;
+  return -1;
+}
+
+/** Decrypt the encrypted introduction points in <b>ipos_encrypted</b> of
+ * length <b>ipos_encrypted_size</b> using <b>descriptor_cookie</b> and
+ * write the result to a newly allocated string that is pointed to by
+ * <b>ipos_decrypted</b> and its length to <b>ipos_decrypted_size</b>.
+ * Return 0 if decryption was successful and -1 otherwise. */
+int
+rend_decrypt_introduction_points(char **ipos_decrypted,
+                                 size_t *ipos_decrypted_size,
+                                 const char *descriptor_cookie,
+                                 const char *ipos_encrypted,
+                                 size_t ipos_encrypted_size)
+{
+  tor_assert(ipos_encrypted);
+  tor_assert(descriptor_cookie);
+  if (ipos_encrypted_size < 2) {
+    log_warn(LD_REND, "Size of encrypted introduction points is too "
+                      "small.");
+    return -1;
+  }
+  if (ipos_encrypted[0] == (int)REND_BASIC_AUTH) {
+    char iv[CIPHER_IV_LEN], client_id[REND_BASIC_AUTH_CLIENT_ID_LEN],
+         session_key[CIPHER_KEY_LEN], *dec;
+    int declen, client_blocks;
+    size_t pos = 0, len, client_entries_len;
+    crypto_digest_t *digest;
+    crypto_cipher_t *cipher;
+    client_blocks = (int) ipos_encrypted[1];
+    client_entries_len = client_blocks * REND_BASIC_AUTH_CLIENT_MULTIPLE *
+                         REND_BASIC_AUTH_CLIENT_ENTRY_LEN;
+    if (ipos_encrypted_size < 2 + client_entries_len + CIPHER_IV_LEN + 1) {
+      log_warn(LD_REND, "Size of encrypted introduction points is too "
+                        "small.");
+      return -1;
+    }
+    memcpy(iv, ipos_encrypted + 2 + client_entries_len, CIPHER_IV_LEN);
+    digest = crypto_digest_new();
+    crypto_digest_add_bytes(digest, descriptor_cookie, REND_DESC_COOKIE_LEN);
+    crypto_digest_add_bytes(digest, iv, CIPHER_IV_LEN);
+    crypto_digest_get_digest(digest, client_id,
+                             REND_BASIC_AUTH_CLIENT_ID_LEN);
+    crypto_digest_free(digest);
+    for (pos = 2; pos < 2 + client_entries_len;
+         pos += REND_BASIC_AUTH_CLIENT_ENTRY_LEN) {
+      if (tor_memeq(ipos_encrypted + pos, client_id,
+                  REND_BASIC_AUTH_CLIENT_ID_LEN)) {
+        /* Attempt to decrypt introduction points. */
+        cipher = crypto_cipher_new(descriptor_cookie);
+        if (crypto_cipher_decrypt(cipher, session_key, ipos_encrypted
+                                  + pos + REND_BASIC_AUTH_CLIENT_ID_LEN,
+                                  CIPHER_KEY_LEN) < 0) {
+          log_warn(LD_REND, "Could not decrypt session key for client.");
+          crypto_cipher_free(cipher);
+          return -1;
+        }
+        crypto_cipher_free(cipher);
+
+        len = ipos_encrypted_size - 2 - client_entries_len - CIPHER_IV_LEN;
+        dec = tor_malloc_zero(len + 1);
+        declen = crypto_cipher_decrypt_with_iv(session_key, dec, len,
+            ipos_encrypted + 2 + client_entries_len,
+            ipos_encrypted_size - 2 - client_entries_len);
+
+        if (declen < 0) {
+          log_warn(LD_REND, "Could not decrypt introduction point string.");
+          tor_free(dec);
+          return -1;
+        }
+        if (fast_memcmpstart(dec, declen, "introduction-point ")) {
+          log_warn(LD_REND, "Decrypted introduction points don't "
+                            "look like we could parse them.");
+          tor_free(dec);
+          continue;
+        }
+        *ipos_decrypted = dec;
+        *ipos_decrypted_size = declen;
+        return 0;
+      }
+    }
+    log_warn(LD_REND, "Could not decrypt introduction points. Please "
+             "check your authorization for this service!");
+    return -1;
+  } else if (ipos_encrypted[0] == (int)REND_STEALTH_AUTH) {
+    char *dec;
+    int declen;
+    if (ipos_encrypted_size < CIPHER_IV_LEN + 2) {
+      log_warn(LD_REND, "Size of encrypted introduction points is too "
+                        "small.");
+      return -1;
+    }
+    dec = tor_malloc_zero(ipos_encrypted_size - CIPHER_IV_LEN - 1 + 1);
+
+    declen = crypto_cipher_decrypt_with_iv(descriptor_cookie, dec,
+                                           ipos_encrypted_size -
+                                               CIPHER_IV_LEN - 1,
+                                           ipos_encrypted + 1,
+                                           ipos_encrypted_size - 1);
+
+    if (declen < 0) {
+      log_warn(LD_REND, "Decrypting introduction points failed!");
+      tor_free(dec);
+      return -1;
+    }
+    *ipos_decrypted = dec;
+    *ipos_decrypted_size = declen;
+    return 0;
+  } else {
+    log_warn(LD_REND, "Unknown authorization type number: %d",
+             ipos_encrypted[0]);
+    return -1;
+  }
+}
+
+/** Parse the encoded introduction points in <b>intro_points_encoded</b> of
+ * length <b>intro_points_encoded_size</b> and write the result to the
+ * descriptor in <b>parsed</b>; return the number of successfully parsed
+ * introduction points or -1 in case of a failure. */
+int
+rend_parse_introduction_points(rend_service_descriptor_t *parsed,
+                               const char *intro_points_encoded,
+                               size_t intro_points_encoded_size)
+{
+  const char *current_ipo, *end_of_intro_points;
+  smartlist_t *tokens = NULL;
+  directory_token_t *tok;
+  rend_intro_point_t *intro;
+  extend_info_t *info;
+  int result, num_ok=1;
+  memarea_t *area = NULL;
+  tor_assert(parsed);
+  /** Function may only be invoked once. */
+  tor_assert(!parsed->intro_nodes);
+  if (!intro_points_encoded || intro_points_encoded_size == 0) {
+    log_warn(LD_REND, "Empty or zero size introduction point list");
+    goto err;
+  }
+  /* Consider one intro point after the other. */
+  current_ipo = intro_points_encoded;
+  end_of_intro_points = intro_points_encoded + intro_points_encoded_size;
+  tokens = smartlist_new();
+  parsed->intro_nodes = smartlist_new();
+  area = memarea_new();
+
+  while (!fast_memcmpstart(current_ipo, end_of_intro_points-current_ipo,
+                      "introduction-point ")) {
+    /* Determine end of string. */
+    const char *eos = tor_memstr(current_ipo, end_of_intro_points-current_ipo,
+                                 "\nintroduction-point ");
+    if (!eos)
+      eos = end_of_intro_points;
+    else
+      eos = eos+1;
+    tor_assert(eos <= intro_points_encoded+intro_points_encoded_size);
+    /* Free tokens and clear token list. */
+    SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
+    smartlist_clear(tokens);
+    memarea_clear(area);
+    /* Tokenize string. */
+    if (tokenize_string(area, current_ipo, eos, tokens, ipo_token_table, 0)) {
+      log_warn(LD_REND, "Error tokenizing introduction point");
+      goto err;
+    }
+    /* Advance to next introduction point, if available. */
+    current_ipo = eos;
+    /* Check minimum allowed length of introduction point. */
+    if (smartlist_len(tokens) < 5) {
+      log_warn(LD_REND, "Impossibly short introduction point.");
+      goto err;
+    }
+    /* Allocate new intro point and extend info. */
+    intro = tor_malloc_zero(sizeof(rend_intro_point_t));
+    info = intro->extend_info = tor_malloc_zero(sizeof(extend_info_t));
+    /* Parse identifier. */
+    tok = find_by_keyword(tokens, R_IPO_IDENTIFIER);
+    if (base32_decode(info->identity_digest, DIGEST_LEN,
+                      tok->args[0], REND_INTRO_POINT_ID_LEN_BASE32) < 0) {
+      log_warn(LD_REND, "Identity digest contains illegal characters: %s",
+               tok->args[0]);
+      rend_intro_point_free(intro);
+      goto err;
+    }
+    /* Write identifier to nickname. */
+    info->nickname[0] = '$';
+    base16_encode(info->nickname + 1, sizeof(info->nickname) - 1,
+                  info->identity_digest, DIGEST_LEN);
+    /* Parse IP address. */
+    tok = find_by_keyword(tokens, R_IPO_IP_ADDRESS);
+    if (tor_addr_parse(&info->addr, tok->args[0])<0) {
+      log_warn(LD_REND, "Could not parse introduction point address.");
+      rend_intro_point_free(intro);
+      goto err;
+    }
+    if (tor_addr_family(&info->addr) != AF_INET) {
+      log_warn(LD_REND, "Introduction point address was not ipv4.");
+      rend_intro_point_free(intro);
+      goto err;
+    }
+
+    /* Parse onion port. */
+    tok = find_by_keyword(tokens, R_IPO_ONION_PORT);
+    info->port = (uint16_t) tor_parse_long(tok->args[0],10,1,65535,
+                                           &num_ok,NULL);
+    if (!info->port || !num_ok) {
+      log_warn(LD_REND, "Introduction point onion port %s is invalid",
+               escaped(tok->args[0]));
+      rend_intro_point_free(intro);
+      goto err;
+    }
+    /* Parse onion key. */
+    tok = find_by_keyword(tokens, R_IPO_ONION_KEY);
+    if (!crypto_pk_public_exponent_ok(tok->key)) {
+      log_warn(LD_REND,
+               "Introduction point's onion key had invalid exponent.");
+      rend_intro_point_free(intro);
+      goto err;
+    }
+    info->onion_key = tok->key;
+    tok->key = NULL; /* Prevent free */
+    /* Parse service key. */
+    tok = find_by_keyword(tokens, R_IPO_SERVICE_KEY);
+    if (!crypto_pk_public_exponent_ok(tok->key)) {
+      log_warn(LD_REND,
+               "Introduction point key had invalid exponent.");
+      rend_intro_point_free(intro);
+      goto err;
+    }
+    intro->intro_key = tok->key;
+    tok->key = NULL; /* Prevent free */
+    /* Add extend info to list of introduction points. */
+    smartlist_add(parsed->intro_nodes, intro);
+  }
+  result = smartlist_len(parsed->intro_nodes);
+  goto done;
+
+ err:
+  result = -1;
+
+ done:
+  /* Free tokens and clear token list. */
+  if (tokens) {
+    SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
+    smartlist_free(tokens);
+  }
+  if (area)
+    memarea_drop_all(area);
+
+  return result;
+}
+
+/** Parse the content of a client_key file in <b>ckstr</b> and add
+ * rend_authorized_client_t's for each parsed client to
+ * <b>parsed_clients</b>. Return the number of parsed clients as result
+ * or -1 for failure. */
+int
+rend_parse_client_keys(strmap_t *parsed_clients, const char *ckstr)
+{
+  int result = -1;
+  smartlist_t *tokens;
+  directory_token_t *tok;
+  const char *current_entry = NULL;
+  memarea_t *area = NULL;
+  char *err_msg = NULL;
+  if (!ckstr || strlen(ckstr) == 0)
+    return -1;
+  tokens = smartlist_new();
+  /* Begin parsing with first entry, skipping comments or whitespace at the
+   * beginning. */
+  area = memarea_new();
+  current_entry = eat_whitespace(ckstr);
+  while (!strcmpstart(current_entry, "client-name ")) {
+    rend_authorized_client_t *parsed_entry;
+    /* Determine end of string. */
+    const char *eos = strstr(current_entry, "\nclient-name ");
+    if (!eos)
+      eos = current_entry + strlen(current_entry);
+    else
+      eos = eos + 1;
+    /* Free tokens and clear token list. */
+    SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
+    smartlist_clear(tokens);
+    memarea_clear(area);
+    /* Tokenize string. */
+    if (tokenize_string(area, current_entry, eos, tokens,
+                        client_keys_token_table, 0)) {
+      log_warn(LD_REND, "Error tokenizing client keys file.");
+      goto err;
+    }
+    /* Advance to next entry, if available. */
+    current_entry = eos;
+    /* Check minimum allowed length of token list. */
+    if (smartlist_len(tokens) < 2) {
+      log_warn(LD_REND, "Impossibly short client key entry.");
+      goto err;
+    }
+    /* Parse client name. */
+    tok = find_by_keyword(tokens, C_CLIENT_NAME);
+    tor_assert(tok == smartlist_get(tokens, 0));
+    tor_assert(tok->n_args == 1);
+
+    if (!rend_valid_client_name(tok->args[0])) {
+      log_warn(LD_CONFIG, "Illegal client name: %s. (Length must be "
+               "between 1 and %d, and valid characters are "
+               "[A-Za-z0-9+-_].)", tok->args[0], REND_CLIENTNAME_MAX_LEN);
+      goto err;
+    }
+    /* Check if client name is duplicate. */
+    if (strmap_get(parsed_clients, tok->args[0])) {
+      log_warn(LD_CONFIG, "HiddenServiceAuthorizeClient contains a "
+               "duplicate client name: '%s'. Ignoring.", tok->args[0]);
+      goto err;
+    }
+    parsed_entry = tor_malloc_zero(sizeof(rend_authorized_client_t));
+    parsed_entry->client_name = tor_strdup(tok->args[0]);
+    strmap_set(parsed_clients, parsed_entry->client_name, parsed_entry);
+    /* Parse client key. */
+    tok = find_opt_by_keyword(tokens, C_CLIENT_KEY);
+    if (tok) {
+      parsed_entry->client_key = tok->key;
+      tok->key = NULL; /* Prevent free */
+    }
+
+    /* Parse descriptor cookie. */
+    tok = find_by_keyword(tokens, C_DESCRIPTOR_COOKIE);
+    tor_assert(tok->n_args == 1);
+    if (rend_auth_decode_cookie(tok->args[0], parsed_entry->descriptor_cookie,
+                                NULL, &err_msg) < 0) {
+      tor_assert(err_msg);
+      log_warn(LD_REND, "%s", err_msg);
+      tor_free(err_msg);
+      goto err;
+    }
+  }
+  result = strmap_size(parsed_clients);
+  goto done;
+ err:
+  result = -1;
+ done:
+  /* Free tokens and clear token list. */
+  SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
+  smartlist_free(tokens);
+  if (area)
+    memarea_drop_all(area);
+  return result;
+}
diff --git a/src/feature/rend/rendparse.h b/src/feature/rend/rendparse.h
new file mode 100644
index 0000000000..337d3e3b1f
--- /dev/null
+++ b/src/feature/rend/rendparse.h
@@ -0,0 +1,32 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file rend_parse.h
+ * \brief Header file for rend_parse.c.
+ **/
+
+#ifndef TOR_REND_PARSE_H
+#define TOR_REND_PARSE_H
+
+int rend_parse_v2_service_descriptor(rend_service_descriptor_t **parsed_out,
+                                     char *desc_id_out,
+                                     char **intro_points_encrypted_out,
+                                     size_t *intro_points_encrypted_size_out,
+                                     size_t *encoded_size_out,
+                                     const char **next_out, const char *desc,
+                                     int as_hsdir);
+int rend_decrypt_introduction_points(char **ipos_decrypted,
+                                     size_t *ipos_decrypted_size,
+                                     const char *descriptor_cookie,
+                                     const char *ipos_encrypted,
+                                     size_t ipos_encrypted_size);
+int rend_parse_introduction_points(rend_service_descriptor_t *parsed,
+                                   const char *intro_points_encoded,
+                                   size_t intro_points_encoded_size);
+int rend_parse_client_keys(strmap_t *parsed_clients, const char *str);
+
+#endif
diff --git a/src/feature/rend/rendservice.c b/src/feature/rend/rendservice.c
index bcd123f371..e70694b788 100644
--- a/src/feature/rend/rendservice.c
+++ b/src/feature/rend/rendservice.c
@@ -35,6 +35,7 @@
 #include "feature/nodelist/routerset.h"
 #include "feature/rend/rendclient.h"
 #include "feature/rend/rendcommon.h"
+#include "feature/rend/rendparse.h"
 #include "feature/rend/rendservice.h"
 #include "feature/stats/predict_ports.h"
 #include "lib/crypt_ops/crypto_dh.h"