Stem Docs

Server Descriptor

Server Descriptor

Parsing for Tor server descriptors, which contains the infrequently changing information about a Tor relay (contact information, exit policy, public keys, etc). This information is provided from a few sources...

Module Overview:

ServerDescriptor - Tor server descriptor.
  |- RelayDescriptor - Server descriptor for a relay.
  |  +- make_router_status_entry - Creates a router status entry for this descriptor.
  |- BridgeDescriptor - Scrubbed server descriptor for a bridge.
  |  |- is_scrubbed - checks if our content has been properly scrubbed
  |  +- get_scrubbing_issues - description of issues with our scrubbing
  |- digest - calculates the upper-case hex digest value for our content
  |- get_annotations - dictionary of content prior to the descriptor entry
  +- get_annotation_lines - lines that provided the annotations

Preferred method of distributing this relay if a bridge.

New in version 1.6.0.

BridgeDistribution Description
ANY No proference, BridgeDB will pick how the bridge is distributed.
HTTPS Provided via the web interface.
EMAIL Provided in response to emails to
MOAT Provided in interactive menus within Tor Browser.
HYPHAE Provided via a cryptographic invitation-based system.
class stem.descriptor.server_descriptor.ServerDescriptor(raw_contents, validate=False, annotations=None)[source]

Bases: stem.descriptor.Descriptor

Common parent for server descriptors.

  • nickname (str) -- * relay's nickname
  • fingerprint (str) -- identity key fingerprint
  • published (datetime) -- * time in UTC when this descriptor was made
  • address (str) -- * IPv4 address of the relay
  • or_port (int) -- * port used for relaying
  • socks_port (int) -- * port used as client (deprecated, always None)
  • dir_port (int) -- * port used for descriptor mirroring
  • platform (bytes) -- line with operating system and tor version
  • tor_version (stem.version.Version) -- version of tor
  • operating_system (str) -- operating system
  • uptime (int) -- uptime when published in seconds
  • contact (bytes) -- contact information
  • exit_policy (stem.exit_policy.ExitPolicy) -- * stated exit policy
  • exit_policy_v6 (stem.exit_policy.MicroExitPolicy) -- * exit policy for IPv6
  • bridge_distribution (BridgeDistribution) -- * preferred method of providing this relay's address if a bridge
  • family (set) -- * nicknames or fingerprints of declared family
  • average_bandwidth (int) -- * average rate it's willing to relay in bytes/s
  • burst_bandwidth (int) -- * burst rate it's willing to relay in bytes/s
  • observed_bandwidth (int) -- * estimated capacity based on usage in bytes/s
  • link_protocols (list) -- link protocols supported by the relay
  • circuit_protocols (list) -- circuit protocols supported by the relay
  • hibernating (bool) -- * hibernating when published
  • allow_single_hop_exits (bool) -- * flag if single hop exiting is allowed
  • allow_tunneled_dir_requests (bool) -- * flag if tunneled directory requests are accepted
  • extra_info_cache (bool) -- * flag if a mirror for extra-info documents
  • extra_info_digest (str) -- upper-case hex encoded digest of our extra-info document
  • extra_info_sha256_digest (str) -- base64 encoded sha256 digest of our extra-info document
  • eventdns (bool) -- flag for evdns backend (deprecated, always unset)
  • ntor_onion_key (str) -- base64 key used to encrypt EXTEND in the ntor protocol
  • or_addresses (list) -- * alternative for our address/or_port attributes, each entry is a tuple of the form (address (str), port (int), is_ipv6 (bool))
  • protocols (dict) -- mapping of protocols to their supported versions

Deprecated, moved to extra-info descriptor...

  • read_history_end (datetime) -- end of the sampling interval
  • read_history_interval (int) -- seconds per interval
  • read_history_values (list) -- bytes read during each interval
  • write_history_end (datetime) -- end of the sampling interval
  • write_history_interval (int) -- seconds per interval
  • write_history_values (list) -- bytes written during each interval

* attribute is either required when we're parsed with validation or has a default value, others are left as None if undefined

Changed in version 1.5.0: Added the allow_tunneled_dir_requests attribute.

Changed in version 1.6.0: Added the extra_info_sha256_digest, protocols, and bridge_distribution attributes.


Provides the hex encoded sha1 of our content. This value is part of the network status entry for this relay.

Returns:unicode with the upper-case hex digest value for this server descriptor
get_annotations(*args, **kwds)[source]

Provides content that appeared prior to the descriptor. If this comes from the cached-descriptors file then this commonly contains content like...

@downloaded-at 2012-03-18 21:18:29
@source ""
Returns:dict with the key/value pairs in our annotations

Provides the lines of content that appeared prior to the descriptor. This is the same as the get_annotations() results, but with the unparsed lines and ordering retained.

Returns:list with the lines of annotation that came before this descriptor
class stem.descriptor.server_descriptor.RelayDescriptor(raw_contents, validate=False, annotations=None, skip_crypto_validation=False)[source]

Bases: stem.descriptor.server_descriptor.ServerDescriptor

Server descriptor (descriptor specification)

  • certificate (stem.certificate.Ed25519Certificate) -- ed25519 certificate
  • ed25519_certificate (str) -- base64 encoded ed25519 certificate
  • ed25519_master_key (str) -- base64 encoded master key for our ed25519 certificate
  • ed25519_signature (str) -- signature of this document using ed25519
  • onion_key (str) -- * key used to encrypt EXTEND cells
  • onion_key_crosscert (str) -- signature generated using the onion_key
  • ntor_onion_key_crosscert (str) -- signature generated using the ntor-onion-key
  • ntor_onion_key_crosscert_sign (str) -- sign of the corresponding ed25519 public key
  • signing_key (str) -- * relay's long-term identity key
  • signature (str) -- * signature for this descriptor

* attribute is required when we're parsed with validation

Changed in version 1.5.0: Added the ed25519_certificate, ed25519_master_key, ed25519_signature, onion_key_crosscert, ntor_onion_key_crosscert, and ntor_onion_key_crosscert_sign attributes.

Changed in version 1.6.0: Moved from the deprecated pycrypto module to cryptography for validating signatures.

Changed in version 1.6.0: Added the certificate attribute.

Deprecated since version 1.6.0: Our ed25519_certificate is deprecated in favor of our new certificate attribute. The base64 encoded certificate is available via the certificate's encoded attribute.

Changed in version 1.6.0: Added the skip_crypto_validation constructor argument.

classmethod content(attr=None, exclude=(), sign=False, signing_key=None)[source]
classmethod create(attr=None, exclude=(), validate=True, sign=False, signing_key=None)[source]
digest(*args, **kwds)[source]

Provides the digest of our descriptor's content.

Returns:the digest string encoded in uppercase hex
Raises :ValueError if the digest cannot be calculated

Provides a RouterStatusEntryV3 for this descriptor content.

New in version 1.6.0.

Returns:RouterStatusEntryV3 that would be in the consensus
class stem.descriptor.server_descriptor.BridgeDescriptor(raw_contents, validate=False, annotations=None)[source]

Bases: stem.descriptor.server_descriptor.ServerDescriptor

Bridge descriptor (bridge descriptor specification)

  • ed25519_certificate_hash (str) -- sha256 hash of the original identity-ed25519
  • router_digest_sha256 (str) -- sha256 digest of this document

Changed in version 1.5.0: Added the ed25519_certificate_hash and router_digest_sha256 attributes. Also added ntor_onion_key (previously this only belonged to unsanitized descriptors).

classmethod content(attr=None, exclude=(), sign=False)[source]

Checks if we've been properly scrubbed in accordance with the bridge descriptor specification. Validation is a moving target so this may not be fully up to date.

Returns:True if we're scrubbed, False otherwise
get_scrubbing_issues(*args, **kwds)[source]

Provides issues with our scrubbing.

Returns:list of strings which describe issues we have with our scrubbing, this list is empty if we're properly scrubbed