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$Id: control-spec.txt 9484 2007-02-05 19:15:13Z nickm $ TC: A Tor control protocol (Version 1) 0. Scope This document describes an implementation-specific protocol that is used for other programs (such as frontend user-interfaces) to communicate with a locally running Tor process. It is not part of the Tor onion routing protocol. This protocol replaces version 0 of TC, which is now deprecated. For reference, TC is described in "control-spec-v0.txt". Implementors are recommended to avoid using TC directly, but instead to use a library that can easily be updated to use the newer protocol. (Version 0 is used by Tor versions 0.1.0.x; the protocol in this document only works with Tor versions in the 0.1.1.x series and later.) 1. Protocol outline TC is a bidirectional message-based protocol. It assumes an underlying stream for communication between a controlling process (the "client" or "controller") and a Tor process (or "server"). The stream may be implemented via TCP, TLS-over-TCP, a Unix-domain socket, or so on, but it must provide reliable in-order delivery. For security, the stream should not be accessible by untrusted parties. In TC, the client and server send typed messages to each other over the underlying stream. The client sends "commands" and the server sends "replies". By default, all messages from the server are in response to messages from the client. Some client requests, however, will cause the server to send messages to the client indefinitely far into the future. Such "asynchronous" replies are marked as such. Servers respond to messages in the order messages are received. 2. Message format 2.1. Description format The message formats listed below use ABNF as described in RFC 2234. The protocol itself is loosely based on SMTP (see RFC 2821). We use the following nonterminals from RFC 2822: atom, qcontent We define the following general-use nonterminals: String = DQUOTE *qcontent DQUOTE There are explicitly no limits on line length. All 8-bit characters are permitted unless explicitly disallowed. 2.2. Commands from controller to Tor Command = Keyword Arguments CRLF / "+" Keyword Arguments CRLF Data Keyword = 1*ALPHA Arguments = *(SP / VCHAR) Specific commands and their arguments are described below in section 3. 2.3. Replies from Tor to the controller Reply = *(MidReplyLine / DataReplyLine) EndReplyLine MidReplyLine = "-" ReplyLine DataReplyLine = "+" ReplyLine Data EndReplyLine = SP ReplyLine ReplyLine = StatusCode [ SP ReplyText ] CRLF ReplyText = XXXX StatusCode = XXXX Specific replies are mentioned below in section 3, and described more fully in section 4. 2.4. General-use tokens ; Identifiers for servers. ServerID = Nickname / Fingerprint Nickname = 1*19 NicknameChar NicknameChar = "a"-"z" / "A"-"Z" / "0" - "9" Fingerprint = "$" 40*HEXDIG ; A "=" indicates that the given nickname is canonical; a "~" indicates ; that the given nickname is not canonical. LongName = Fingerprint [ ( "=" / "~" ) Nickname ] ; How a controller tells Tor about a particular OR. There are four ; possible formats: ; $Digest -- The router whose identity key hashes to the given digest. ; This is the preferred way to refer to an OR. ; $Digest~Name -- The router whose identity key hashes to the given ; digest, but only if the router has the given nickname. ; $Digest=Name -- The router whose identity key hashes to the given ; digest, but only if the router is Named and has the given ; nickname. ; Name -- The Named router with the given nickname, or, if no such ; router exists, any router whose nickname matches the one given. ; This is not a safe way to refer to routers, since Named status ; could under some circumstances change over time. ServerSpec = LongName / Nickname ; Unique identifiers for streams or circuits. Currently, Tor only ; uses digits, but this may change StreamID = 1*16 IDChar CircuitID = 1*16 IDChar IDChar = ALPHA / DIGIT Address = ip4-address / ip6-address / hostname (XXXX Define these) ; A "Data" section is a sequence of octets concluded by the terminating ; sequence CRLF "." CRLF. The terminating sequence may not appear in the ; body of the data. Leading periods on lines in the data are escaped with ; an additional leading period as in RFC 2821 section 4.5.2. Data = *DataLine "." CRLF DataLine = CRLF / "." 1*LineItem CRLF / NonDotItem *LineItem CRLF LineItem = NonCR / 1*CR NonCRLF NonDotItem = NonDotCR / 1*CR NonCRLF 3. Commands All commands and other keywords are case-insensitive. 3.1. SETCONF Change the value of one or more configuration variables. The syntax is: "SETCONF" 1*(SP keyword ["=" String]) CRLF Tor behaves as though it had just read each of the key-value pairs from its configuration file. Keywords with no corresponding values have their configuration values reset to 0 or NULL (use RESETCONF if you want to set it back to its default). SETCONF is all-or-nothing: if there is an error in any of the configuration settings, Tor sets none of them. Tor responds with a "250 configuration values set" reply on success. If some of the listed keywords can't be found, Tor replies with a "552 Unrecognized option" message. Otherwise, Tor responds with a "513 syntax error in configuration values" reply on syntax error, or a "553 impossible configuration setting" reply on a semantic error. When a configuration option takes multiple values, or when multiple configuration keys form a context-sensitive group (see GETCONF below), then setting _any_ of the options in a SETCONF command is taken to reset all of the others. For example, if two ORBindAddress values are configured, and a SETCONF command arrives containing a single ORBindAddress value, the new command's value replaces the two old values. 3.2. RESETCONF Remove all settings for a given configuration option entirely, assign its default value (if any), and then assign the String provided. Typically the String is left empty, to simply set an option back to its default. The syntax is: "RESETCONF" 1*(SP keyword ["=" String]) CRLF Otherwise it behaves like SETCONF above. 3.3. GETCONF Request the value of a configuration variable. The syntax is: "GETCONF" 1*(SP keyword) CRLF If all of the listed keywords exist in the Tor configuration, Tor replies with a series of reply lines of the form: 250 keyword=value If any option is set to a 'default' value semantically different from an empty string, Tor may reply with a reply line of the form: 250 keyword If some of the listed keywords can't be found, Tor replies with a "552 unknown configuration keyword" message. If an option appears multiple times in the configuration, all of its key-value pairs are returned in order. Some options are context-sensitive, and depend on other options with different keywords. These cannot be fetched directly. Currently there is only one such option: clients should use the "HiddenServiceOptions" virtual keyword to get all HiddenServiceDir, HiddenServicePort, HiddenServiceNodes, and HiddenServiceExcludeNodes option settings. 3.4. SETEVENTS Request the server to inform the client about interesting events. The syntax is: "SETEVENTS" [SP "EXTENDED"] *(SP EventCode) CRLF EventCode = "CIRC" / "STREAM" / "ORCONN" / "BW" / "DEBUG" / "INFO" / "NOTICE" / "WARN" / "ERR" / "NEWDESC" / "ADDRMAP" / "AUTHDIR_NEWDESCS" / "DESCCHANGED" / "STATUS_GENERAL" / "STATUS_CLIENT" / "STATUS_SERVER" / "GUARDS" / "NS" Any events *not* listed in the SETEVENTS line are turned off; thus, sending SETEVENTS with an empty body turns off all event reporting. The server responds with a "250 OK" reply on success, and a "552 Unrecognized event" reply if one of the event codes isn't recognized. (On error, the list of active event codes isn't changed.) If the flag string "EXTENDED" is provided, Tor may provide extra information with events for this connection; see 4.1 for more information. NOTE: All events on a given connection will be provided in extended format, or none. NOTE: "EXTENDED" is only supported in Tor 0.1.1.9-alpha or later. Each event is described in more detail in Section 4.1. 3.5. AUTHENTICATE Sent from the client to the server. The syntax is: "AUTHENTICATE" [ SP 1*HEXDIG / QuotedString ] CRLF The server responds with "250 OK" on success or "515 Bad authentication" if the authentication cookie is incorrect. The format of the 'cookie' is implementation-dependent; see 5.1 below for information on how the standard Tor implementation handles it. If Tor requires authentication and the controller has not yet sent an AUTHENTICATE message, Tor sends a "514 authentication required" reply to any other kind of message. 3.6. SAVECONF Sent from the client to the server. The syntax is: "SAVECONF" CRLF Instructs the server to write out its config options into its torrc. Server returns "250 OK" if successful, or "551 Unable to write configuration to disk" if it can't write the file or some other error occurs. 3.7. SIGNAL Sent from the client to the server. The syntax is: "SIGNAL" SP Signal CRLF Signal = "RELOAD" / "SHUTDOWN" / "DUMP" / "DEBUG" / "HALT" / "HUP" / "INT" / "USR1" / "USR2" / "TERM" / "NEWNYM" / "CLEARDNSCACHE" The meaning of the signals are: RELOAD -- Reload: reload config items, refetch directory. (like HUP) SHUTDOWN -- Controlled shutdown: if server is an OP, exit immediately. If it's an OR, close listeners and exit after 30 seconds. (like INT) DUMP -- Dump stats: log information about open connections and circuits. (like USR1) DEBUG -- Debug: switch all open logs to loglevel debug. (like USR2) HALT -- Immediate shutdown: clean up and exit now. (like TERM) CLEARDNSCACHE -- Forget the client-side cached IPs for all hostnames. NEWNYM -- Switch to clean circuits, so new application requests don't share any circuits with old ones. Also clears the client-side DNS cache. The server responds with "250 OK" if the signal is recognized (or simply closes the socket if it was asked to close immediately), or "552 Unrecognized signal" if the signal is unrecognized. 3.8. MAPADDRESS Sent from the client to the server. The syntax is: "MAPADDRESS" 1*(Address "=" Address SP) CRLF The first address in each pair is an "original" address; the second is a "replacement" address. The client sends this message to the server in order to tell it that future SOCKS requests for connections to the original address should be replaced with connections to the specified replacement address. If the addresses are well-formed, and the server is able to fulfill the request, the server replies with a 250 message: 250-OldAddress1=NewAddress1 250 OldAddress2=NewAddress2 containing the source and destination addresses. If request is malformed, the server replies with "512 syntax error in command argument". If the server can't fulfill the request, it replies with "451 resource exhausted". The client may decline to provide a body for the original address, and instead send a special null address ("0.0.0.0" for IPv4, "::0" for IPv6, or "." for hostname), signifying that the server should choose the original address itself, and return that address in the reply. The server should ensure that it returns an element of address space that is unlikely to be in actual use. If there is already an address mapped to the destination address, the server may reuse that mapping. If the original address is already mapped to a different address, the old mapping is removed. If the original address and the destination address are the same, the server removes any mapping in place for the original address. Example: C: MAPADDRESS 0.0.0.0=tor.eff.org 1.2.3.4=tor.freehaven.net S: 250-127.192.10.10=tor.eff.org S: 250 1.2.3.4=tor.freehaven.net {Note: This feature is designed to be used to help Tor-ify applications that need to use SOCKS4 or hostname-less SOCKS5. There are three approaches to doing this: 1. Somehow make them use SOCKS4a or SOCKS5-with-hostnames instead. 2. Use tor-resolve (or another interface to Tor's resolve-over-SOCKS feature) to resolve the hostname remotely. This doesn't work with special addresses like x.onion or x.y.exit. 3. Use MAPADDRESS to map an IP address to the desired hostname, and then arrange to fool the application into thinking that the hostname has resolved to that IP. This functionality is designed to help implement the 3rd approach.} Mappings set by the controller last until the Tor process exits: they never expire. If the controller wants the mapping to last only a certain time, then it must explicitly un-map the address when that time has elapsed. 3.9. GETINFO Sent from the client to the server. The syntax is as for GETCONF: "GETINFO" 1*(SP keyword) CRLF one or more NL-terminated strings. The server replies with an INFOVALUE message, or a 551 or 552 error. Unlike GETCONF, this message is used for data that are not stored in the Tor configuration file, and that may be longer than a single line. On success, one ReplyLine is sent for each requested value, followed by a final 250 OK ReplyLine. If a value fits on a single line, the format is: 250-keyword=value If a value must be split over multiple lines, the format is: 250+keyword= value . Recognized keys and their values include: "version" -- The version of the server's software, including the name of the software. (example: "Tor 0.0.9.4") "config-file" -- The location of Tor's configuration file ("torrc"). ["exit-policy/prepend" -- The default exit policy lines that Tor will *prepend* to the ExitPolicy config option. -- Never implemented. Useful?] "exit-policy/default" -- The default exit policy lines that Tor will *append* to the ExitPolicy config option. "desc/id/<OR identity>" or "desc/name/<OR nickname>" -- the latest server descriptor for a given OR, NUL-terminated. "ns/id/<OR identity>" or "ns/name/<OR nickname>" -- the latest network status info for a given OR. Network status info is as given in dir-spec.txt, and reflects the current beliefs of this Tor about the router in question. Like directory clients, controllers MUST tolerate unrecognized flags and lines. The published date and descriptor digest are those believed to be best by this Tor, not necessarily those for a descriptor that Tor currently has. [First implemented in 0.1.2.3-alpha.] "ns/all" -- Network status info for all ORs we have an opinion about, joined by newlines. [First implemented in 0.1.2.3-alpha.] "desc/all-recent" -- the latest server descriptor for every router that Tor knows about. "network-status" -- a space-separated list of all known OR identities. This is in the same format as the router-status line in directories; see dir-spec-v1.txt section 3 for details. (If VERBOSE_NAMES is enabled, the output will not conform to dir-spec-v1.txt; instead, the result will be a space-separated list of LongName, each preceded by a "!" if it is believed to be not running.) "addr-mappings/all" "addr-mappings/config" "addr-mappings/cache" "addr-mappings/control" -- a space-separated list of address mappings, each in the form of "from-address=to-address". The 'config' key returns those address mappings set in the configuration; the 'cache' key returns the mappings in the client-side DNS cache; the 'control' key returns the mappings set via the control interface; the 'all' target returns the mappings set through any mechanism. "address" -- the best guess at our external IP address. If we have no guess, return a 551 error. (Added in 0.1.2.2-alpha) "fingerprint" -- the contents of the fingerprint file that Tor writes as a server, or a 551 if we're not a server currently. (Added in 0.1.2.3-alpha) "circuit-status" A series of lines as for a circuit status event. Each line is of the form: CircuitID SP CircStatus [SP Path] CRLF "stream-status" A series of lines as for a stream status event. Each is of the form: StreamID SP StreamStatus SP CircID SP Target CRLF "orconn-status" A series of lines as for an OR connection status event. Each is of the form: ServerID SP ORStatus CRLF "entry-guards" A series of lines listing the currently chosen entry guards, if any. Each is of the form: ServerID SP (Status-with-time / Status) CRLF Status-with-time = ("down" / "unlisted") SP ISOTime Status = ("up" / "never-connected") [From 0.1.1.4-alpha to 0.1.1.10-alpha, this was called "helper-nodes". Tor still supports calling it that for now, but support will be removed in 0.1.3.x.] "accounting/enabled" "accounting/hibernating" "accounting/bytes" "accounting/bytes-left" "accounting/interval-start" "accounting/interval-wake" "accounting/interval-end" Information about accounting status. If accounting is enabled, "enabled" is 1; otherwise it is 0. The "hibernating" field is "hard" if we are accepting no data; "soft" if we're accepting no new connections, and "awake" if we're not hibernating at all. The "bytes" and "bytes-left" fields contain (read-bytes SP write-bytes), for the start and the rest of the interval respectively. The 'interval-start' and 'interval-end' fields are the borders of the current interval; the 'interval-wake' field is the time within the current interval (if any) where we plan[ned] to start being active. "config/names" A series of lines listing the available configuration options. Each is of the form: OptionName SP OptionType [ SP Documentation ] CRLF OptionName = Keyword OptionType = "Integer" / "TimeInterval" / "DataSize" / "Float" / "Boolean" / "Time" / "CommaList" / "Dependant" / "Virtual" / "String" / "LineList" Documentation = Text "info/names" A series of lines listing the available GETINFO options. Each is of one of these forms: OptionName SP Documentation CRLF OptionPrefix SP Documentation CRLF OptionPrefix = OptionName "/*" "events/names" A space-separated list of all the events supported by this version of Tor's SETEVENTS. "features/names" A space-separated list of all the events supported by this version of Tor's USEFEATURE. "next-circuit/IP:port" XXX todo. "dir/status/authority" "dir/status/fp/<F>" "dir/status/fp/<F1>+<F2>+<F3>" "dir/status/all" "dir/server/fp/<F>" "dir/server/fp/<F1>+<F2>+<F3>" "dir/server/d/<D>" "dir/server/d/<D1>+<D2>+<D3>" "dir/server/authority" "dir/server/all" A series of lines listing directory contents, provided according to the specification for the URLs listed in Section 4.4 of dir-spec.txt. Note that Tor MUST NOT provide private information, such as descriptors for routers not marked as general-purpose. When asked for 'authority' information for which this Tor is not authoritative, Tor replies with an empty string. "status/circuit-established" "status/..." These provide the current internal Tor values for various Tor states. See Section 4.1.10 for explanations. (Only a few of the status events are available as getinfo's currently. Let us know if you want more exposed.) Examples: C: GETINFO version desc/name/moria1 S: 250+desc/name/moria= S: [Descriptor for moria] S: . S: 250-version=Tor 0.1.1.0-alpha-cvs S: 250 OK 3.10. EXTENDCIRCUIT Sent from the client to the server. The format is: "EXTENDCIRCUIT" SP CircuitID SP ServerSpec *("," ServerSpec) SP ("purpose=" Purpose) CRLF This request takes one of two forms: either the CircuitID is zero, in which case it is a request for the server to build a new circuit according to the specified path, or the CircuitID is nonzero, in which case it is a request for the server to extend an existing circuit with that ID according to the specified path. If CircuitID is 0 and "purpose=" is specified, then the circuit's purpose is set. Two choices are recognized: "general" and "controller". If not specified, circuits are created as "general". If the request is successful, the server sends a reply containing a message body consisting of the CircuitID of the (maybe newly created) circuit. The syntax is "250" SP "EXTENDED" SP CircuitID CRLF. 3.11. SETCIRCUITPURPOSE Sent from the client to the server. The format is: "SETCIRCUITPURPOSE" SP CircuitID SP Purpose CRLF This changes the circuit's purpose. See EXTENDCIRCUIT above for details. 3.12. SETROUTERPURPOSE Sent from the client to the server. The format is: "SETROUTERPURPOSE" SP NicknameOrKey SP Purpose CRLF This changes the descriptor's purpose. See +POSTDESCRIPTOR below for details. 3.13. ATTACHSTREAM Sent from the client to the server. The syntax is: "ATTACHSTREAM" SP StreamID SP CircuitID CRLF This message informs the server that the specified stream should be associated with the specified circuit. Each stream may be associated with at most one circuit, and multiple streams may share the same circuit. Streams can only be attached to completed circuits (that is, circuits that have sent a circuit status 'BUILT' event or are listed as built in a GETINFO circuit-status request). If the circuit ID is 0, responsibility for attaching the given stream is returned to Tor. Tor responds with "250 OK" if it can attach the stream, 552 if the circuit or stream didn't exist, or 551 if the stream couldn't be attached for another reason. {Implementation note: Tor will close unattached streams by itself, roughly two minutes after they are born. Let the developers know if that turns out to be a problem.} {Implementation note: By default, Tor automatically attaches streams to circuits itself, unless the configuration variable "__LeaveStreamsUnattached" is set to "1". Attempting to attach streams via TC when "__LeaveStreamsUnattached" is false may cause a race between Tor and the controller, as both attempt to attach streams to circuits.} {Implementation note: You can try to attachstream to a stream that has already sent a connect or resolve request but hasn't succeeded yet, in which case Tor will detach the stream from its current circuit before proceeding with the new attach request.} 3.14. POSTDESCRIPTOR Sent from the client to the server. The syntax is: "+POSTDESCRIPTOR" ("purpose=" Purpose) CRLF Descriptor CRLF "." CRLF This message informs the server about a new descriptor. If Purpose is specified, it must be either "general" or "controller", else we return a 552 error. The descriptor, when parsed, must contain a number of well-specified fields, including fields for its nickname and identity. If there is an error in parsing the descriptor, the server must send a "554 Invalid descriptor" reply. If the descriptor is well-formed but the server chooses not to add it, it must reply with a 251 message whose body explains why the server was not added. If the descriptor is added, Tor replies with "250 OK". 3.15. REDIRECTSTREAM Sent from the client to the server. The syntax is: "REDIRECTSTREAM" SP StreamID SP Address (SP Port) CRLF Tells the server to change the exit address on the specified stream. If Port is specified, changes the destination port as well. No remapping is performed on the new provided address. To be sure that the modified address will be used, this event must be sent after a new stream event is received, and before attaching this stream to a circuit. Tor replies with "250 OK" on success. 3.16. CLOSESTREAM Sent from the client to the server. The syntax is: "CLOSESTREAM" SP StreamID SP Reason *(SP Flag) CRLF Tells the server to close the specified stream. The reason should be one of the Tor RELAY_END reasons given in tor-spec.txt, as a decimal. Flags is not used currently; Tor servers SHOULD ignore unrecognized flags. Tor may hold the stream open for a while to flush any data that is pending. Tor replies with "250 OK" on success, or a 512 if there aren't enough arguments, or a 552 if it doesn't recognize the StreamID or reason. 3.17. CLOSECIRCUIT The syntax is: CLOSECIRCUIT SP CircuitID *(SP Flag) CRLF Flag = "IfUnused" Tells the server to close the specified circuit. If "IfUnused" is provided, do not close the circuit unless it is unused. Other flags may be defined in the future; Tor SHOULD ignore unrecognized flags. Tor replies with "250 OK" on success, or a 512 if there aren't enough arguments, or a 552 if it doesn't recognize the CircuitID. 3.18. QUIT Tells the server to hang up on this controller connection. This command can be used before authenticating. 3.19. USEFEATURE The syntax is: "USEFEATURE" *(SP FeatureName) CRLF FeatureName = 1*(ALPHA / DIGIT / "_" / "-") Sometimes extensions to the controller protocol break compatibility with older controllers. In this case, whenever possible, the extensions are first included in Tor disabled by default, and only enabled on a given controller connection when the "USEFEATURE" command is given. Once a "USEFEATURE" command is given, it applies to all subsequent interactions on the same connection; to disable an enabled feature, a new controller connection must be opened. This is a forward-compatibility mechanism; each feature will eventually become a regular part of the control protocol in some future version of Tor. Tor will ignore a request to use any feature that is already on by default. Tor will give a "552" error if any requested feature is not recognized. Feature names are case-insensitive. EXTENDED_EVENTS Same as passing 'EXTENDED' to SETEVENTS; this is the preferred way to request the extended event syntax. This will not be always-enabled until at least XXX (or, at least two stable releases after XXX, the release where it was first used for anything.) VERBOSE_NAMES Instead of ServerID as specified above, the controller should identify ORs by LongName in events and GETINFO results. This format is strictly more informative: rather than including Nickname for known Named routers and Fingerprint for unknown or unNamed routers, the LongName format includes a Fingerprint, an indication of Named status, and a Nickname (if one is known). This will not be always-enabled until at least 0.1.4.x (or at least two stable releases after 0.1.2.2-alpha, the release where it was first available.) 4. Replies Reply codes follow the same 3-character format as used by SMTP, with the first character defining a status, the second character defining a subsystem, and the third designating fine-grained information. The TC protocol currently uses the following first characters: 2yz Positive Completion Reply The command was successful; a new request can be started. 4yz Temporary Negative Completion reply The command was unsuccessful but might be reattempted later. 5yz Permanent Negative Completion Reply The command was unsuccessful; the client should not try exactly that sequence of commands again. 6yz Asynchronous Reply Sent out-of-order in response to an earlier SETEVENTS command. The following second characters are used: x0z Syntax Sent in response to ill-formed or nonsensical commands. x1z Protocol Refers to operations of the Tor Control protocol. x5z Tor Refers to actual operations of Tor system. The following codes are defined: 250 OK 251 Operation was unnecessary [Tor has declined to perform the operation, but no harm was done.] 451 Resource exhausted 500 Syntax error: protocol 510 Unrecognized command 511 Unimplemented command 512 Syntax error in command argument 513 Unrecognized command argument 514 Authentication required 515 Bad authentication 550 Unspecified Tor error 551 Internal error [Something went wrong inside Tor, so that the client's request couldn't be fulfilled.] 552 Unrecognized entity [A configuration key, a stream ID, circuit ID, event, mentioned in the command did not actually exist.] 553 Invalid configuration value [The client tried to set a configuration option to an incorrect, ill-formed, or impossible value.] 554 Invalid descriptor 555 Unmanaged entity 650 Asynchronous event notification Unless specified to have specific contents, the human-readable messages in error replies should not be relied upon to match those in this document. 4.1. Asynchronous events These replies can be sent after a corresponding SETEVENTS command has been received. They will not be interleaved with other Reply elements, but they can appear between a command and its corresponding reply. For example, this sequence is possible: C: SETEVENTS CIRC S: 250 OK C: GETCONF SOCKSPORT ORPORT S: 650 CIRC 1000 EXTENDED moria1,moria2 S: 250-SOCKSPORT=9050 S: 250 ORPORT=0 But this sequence is disallowed: C: SETEVENTS CIRC S: 250 OK C: GETCONF SOCKSPORT ORPORT S: 250-SOCKSPORT=9050 S: 650 CIRC 1000 EXTENDED moria1,moria2 S: 250 ORPORT=0 Clients MUST tolerate more arguments in an asynchonous reply than expected, and MUST tolerate more lines in an asynchronous reply than expected. For instance, a client that expects a CIRC message like: 650 CIRC 1000 EXTENDED moria1,moria2 must tolerate: 650-CIRC 1000 EXTENDED moria1,moria2 0xBEEF 650-EXTRAMAGIC=99 650 ANONYMITY=high If clients ask for extended events, then each event line as specified below will be followed by additional extensions. Additional lines will be of the form "650" ("-"/" ") KEYWORD ["=" ARGUMENTS] CRLF Additional arguments will be of the form SP KEYWORD ["=" ( QuotedString / * NonSpDquote ) ] Such clients MUST tolerate lines with keywords they do not recognize. 4.1.1. Circuit status changed The syntax is: "650" SP "CIRC" SP CircuitID SP CircStatus [SP Path] [SP "REASON=" Reason [SP "REMOTE_REASON=" Reason]] CRLF CircStatus = "LAUNCHED" / ; circuit ID assigned to new circuit "BUILT" / ; all hops finished, can now accept streams "EXTENDED" / ; one more hop has been completed "FAILED" / ; circuit closed (was not built) "CLOSED" ; circuit closed (was built) Path = ServerID *("," ServerID) Reason = "NONE" / "TORPROTOCOL" / "INTERNAL" / "REQUESTED" / "HIBERNATING" / "RESOURCELIMIT" / "CONNECTFAILED" / "OR_IDENTITY" / "OR_CONN_CLOSED" / "TIMEOUT" / "FINISHED" / "DESTROYED" / "NOPATH" / "NOSUCHSERVICE" The path is provided only when the circuit has been extended at least one hop. The "REASON" field is provided only for FAILED and CLOSED events, and only if extended events are enabled (see 3.19). Clients MUST accept reasons not listed above. Reasons are as given in tor-spec.txt, except for: NOPATH (Not enough nodes to make circuit) The "REMOTE_REASON" field is provided only when we receive a DESTROY or TRUNCATE cell, and only if extended events are enabled. It contains the actual reason given by the remote OR for closing the circuit. Clients MUST accept reasons not listed above. Reasons are as listed in tor-spec.txt. 4.1.2. Stream status changed The syntax is: "650" SP "STREAM" SP StreamID SP StreamStatus SP CircID SP Target [SP "REASON=" Reason [ SP "REMOTE_REASON=" Reason ]] CRLF StreamStatus = "NEW" / ; New request to connect "NEWRESOLVE" / ; New request to resolve an address "REMAP" / ; Address re-mapped to another "SENTCONNECT" / ; Sent a connect cell along a circuit "SENTRESOLVE" / ; Sent a resolve cell along a circuit "SUCCEEDED" / ; Received a reply; stream established "FAILED" / ; Stream failed and not retriable "CLOSED" / ; Stream closed "DETACHED" ; Detached from circuit; still retriable Target = Address ":" Port The circuit ID designates which circuit this stream is attached to. If the stream is unattached, the circuit ID "0" is given. Reason = "MISC" / "RESOLVEFAILED" / "CONNECTREFUSED" / "EXITPOLICY" / "DESTROY" / "DONE" / "TIMEOUT" / "HIBERNATING" / "INTERNAL"/ "RESOURCELIMIT" / "CONNRESET" / "TORPROTOCOL" / "NOTDIRECTORY" / "END" The "REASON" field is provided only for FAILED, CLOSED, and DETACHED events, and only if extended events are enabled (see 3.19). Clients MUST accept reasons not listed above. Reasons are as given in tor-spec.txt, except for: END (We received a RELAY_END cell from the other side of thise stream.) The "REMOTE_REASON" field is provided only when we receive a RELAY_END cell, and only if extended events are enabled. It contains the actual reason given by the remote OR for closing the stream. Clients MUST accept reasons not listed above. Reasons are as listed in tor-spec.txt. 4.1.3. OR Connection status changed The syntax is: "650" SP "ORCONN" SP (ServerID / Target) SP ORStatus [ SP "REASON=" Reason ] [ SP "NCIRCS=" NumCircuits ] ORStatus = "NEW" / "LAUNCHED" / "CONNECTED" / "FAILED" / "CLOSED" NEW is for incoming connections, and LAUNCHED is for outgoing connections. CONNECTED means the TLS handshake has finished (in either direction). FAILED means a connection is being closed that hasn't finished its handshake, and CLOSED is for connections that have handshaked. A ServerID is specified unless it's a NEW connection, in which case we don't know what server it is yet, so we use Address:Port. If extended events are enabled (see 3.19), optional reason and circuit counting information is provided for CLOSED and FAILED events. Reason = "MISC" / "DONE" / "CONNECTREFUSED" / "IDENTITY" / "CONNECTRESET" / "TIMEOUT" / "NOROUTE" / "IOERROR" NumCircuits counts both established and pending circuits. 4.1.4. Bandwidth used in the last second The syntax is: "650" SP "BW" SP BytesRead SP BytesWritten *(SP Type "=" Num) BytesRead = 1*DIGIT BytesWritten = 1*DIGIT Type = "DIR" / "OR" / "EXIT" / "APP" / ... Num = 1*DIGIT BytesRead and BytesWritten are the totals. In Tor 0.1.x.y-alpha and later, we also include a breakdown of the connection types that used bandwidth this second (not implemented yet). 4.1.5. Log messages The syntax is: "650" SP Severity SP ReplyText or "650+" Severity CRLF Data Severity = "DEBUG" / "INFO" / "NOTICE" / "WARN"/ "ERR" 4.1.6. New descriptors available Syntax: "650" SP "NEWDESC" 1*(SP ServerID) 4.1.7. New Address mapping Syntax: "650" SP "ADDRMAP" SP Address SP Address SP Expiry Expiry = DQUOTE ISOTime DQUOTE / "NEVER" Expiry is expressed as the local time (rather than GMT). [XXX We should rename this to ADDRESSMAP. -RD] [FFF We should add a SOURCE=%s argument for extended events, which specifies what exit node told us this addressmap. -RD] 4.1.8. Descriptors uploaded to us in our role as authoritative dirserver Syntax: "650" "+" "AUTHDIR_NEWDESCS" CRLF Action CRLF Message CRLF Descriptor CRLF "." CRLF Action = "ACCEPTED" / "DROPPED" / "REJECTED" Message = Text 4.1.9. Our descriptor changed Syntax: "650" SP "DESCCHANGED" [First added in 0.1.2.2-alpha.] 4.1.10. Status events Status events (STATUS_GENERAL, STATUS_CLIENT, and STATUS_SERVER) are sent based on occurrences in the Tor process pertaining to the general state of the program. Generally, they correspond to log messages of severity Notice or higher. They differ from log messages in that their format is a specified interface. Syntax: "650" SP StatusType SP StatusSeverity SP StatusAction [SP StatusArguments] CRLF StatusType = "STATUS_GENERAL" / "STATUS_CLIENT" / "STATUS_SERVER" StatusSeverity = "NOTICE" / "WARN" / "ERR" StatusAction = 1*ALPHA StatusArguments = StatusArgument *(SP StatusArgument) StatusArgument = StatusKeyword '=' StatusValue StatusKeyword = 1*(ALNUM / "_") StatusValue = 1*(ALNUM / '_') / QuotedString Action is a string, and Arguments is a series of keyword=value pairs on the same line. Values may be space-terminated strings, or quoted strings. These events are always produced with EXTENDED_EVENTS and VERBOSE_NAMES; see the explanations in the USEFEATURE section for details. Controllers MUST tolerate unrecognized actions, MUST tolerate unrecognized arguments, MUST tolerate missing arguments, and MUST tolerate arguments that arrive in any order. Each event description below is accompanied by a recommendation for controllers. These recommendations are suggestions only; no controller is required to implement them. Actions for STATUS_GENERAL events can be as follows: CLOCK_JUMPED "TIME=NUM" Tor spent enough time without CPU cycles that it has closed all its circuits and will establish them anew. This typically happens when a laptop goes to sleep and then wakes up again. It also happens when the system is swapping so heavily that Tor is starving. The "time" argument specifies the number of seconds Tor thinks it was unconscious for (or alternatively, the number of seconds it went back in time). This status event is sent as NOTICE severity normally, but WARN severity if Tor is acting as a server currently. {Recommendation for controller: ignore it, since we don't really know what the user should do anyway. Hm.} DANGEROUS_VERSION "CURRENT=version" "REASON=NEW/OLD/UNRECOMMENDED" "RECOMMENDED=\"version, version, ...\"" Tor has found that directory servers don't recommend its version of the Tor software. RECOMMENDED is a comma-and-space-separated string of Tor versions that are recommended. REASON is NEW if this version of Tor is newer than any recommended version, OLD if this version of Tor is older than any recommended version, and UNRECOMMENDED if some recommended versions of Tor are newer and some are old than this version. {Controllers may want to suggest that the user upgrade OLD or UNRECOMMENDED versions. NEW versions may be known-insecure, or may simply be development versions.} TOO_MANY_CONNECTIONS "CURRENT=NUM" Tor has reached its ulimit -n or whatever the native limit is on file descriptors or sockets. CURRENT is the number of sockets Tor currently has open. The user should really do something about this. The "current" argument shows the number of connections currently open. {Controllers may recommend that the user increase the limit, or increase it for them. Recommendations should be phrased in an OS-appropriate way and automated when possible.} BUG "REASON=STRING" Tor has encountered a situation that its developers never expected, and the developers would like to learn that it happened. Perhaps the controller can explain this to the user and encourage her to file a bug report? {Controllers should log bugs, but shouldn't annoy the user in case a bug appears frequently.} CLOCK_SKEWED SKEW="+" / "-" SECONDS SOURCE="DIRSERV:IP:Port" / "NETWORKSTATUS:IP:PORT" If "SKEW" is present, it's an estimate of how far we are from the time declared in the source. If the source is a DIRSERV, we got the current time from a connection to a dirserver. If the source is a NETWORKSTATUS, we decided we're skewed because we got a networkstatus from far in the future. {Controllers may want to warn the user if the skew is high, or if multiple skew messages appear at severity WARN. Controllers shouldn't blindly adjust the clock, since the more accurate source of skew info (DIRSERV) is currently unauthenticated.} BAD_LIBEVENT "METHOD=" libevent method "VERSION=" libevent version "BADNESS=" "BROKEN" / "BUGGY" / "SLOW" "RECOVERED=" "NO" / "YES" Tor knows about bugs in using the configured event method in this version of libevent. "BROKEN" libevents won't work at all; "BUGGY" libevents might work okay; "SLOW" libevents will work fine, but not quickly. If "RECOVERED" is YES, Tor managed to switch to a more reliable (but probably slower!) libevent method. {Controllers may want to warn the user if this event occurs, though generally it's the fault of whoever built the Tor binary and there's not much the user can do besides upgrade libevent or upgrade the binary.} DIR_ALL_UNREACHABLE Tor believes that none of the known directory servers are reachable -- this is most likely because the local network is down or otherwise not working, and might help to explain for the user why Tor appears to be broken. {Controllers may want to warn the user if this event occurs; further action is generally not possible.} Actions for STATUS_CLIENT events can be as follows: ENOUGH_DIR_INFO Tor now knows enough network-status documents and enough server descriptors that it's going to start trying to build circuits now. {Controllers may want to use this event to decide when to indicate progress to their users, but should not interrupt the user's browsing to tell them so.} NOT_ENOUGH_DIR_INFO We discarded expired statuses and router descriptors to fall below the desired threshold of directory information. We won't try to build any circuits until ENOUGH_DIR_INFO occurs again. {Controllers may want to use this event to decide when to indicate progress to their users, but should not interrupt the user's browsing to tell them so.} CIRCUIT_ESTABLISHED Tor is able to establish circuits for client use. This event will only be sent if we just built a circuit that changed our mind -- that is, prior to this event we didn't know whether we could establish circuits. {Suggested use: controllers can notify their users that Tor is ready for use as a client once they see this status event. [Perhaps controllers should also have a timeout if too much time passes and this event hasn't arrived, to give tips on how to troubleshoot. On the other hand, hopefully Tor will send further status events if it can identify the problem.]} CIRCUIT_NOT_ESTABLISHED "REASON=" "EXTERNAL_ADDRESS" / "DIR_ALL_UNREACHABLE" / "CLOCK_JUMPED" We are no longer confident that we can build circuits. The "reason" keyword provides an explanation: which other status event type caused our lack of confidence. {Controllers may want to use this event to decide when to indicate progress to their users, but should not interrupt the user's browsing to do so.} [Note: only REASON=CLOCK_JUMPED is implemented currently.] DANGEROUS_SOCKS "PROTOCOL=SOCKS4/SOCKS5" "ADDRESS=IP:port" A connection was made to Tor's SOCKS port using one of the SOCKS approaches that doesn't support hostnames -- only raw IP addresses. If the client application got this address from gethostbyname(), it may be leaking target addresses via DNS. {Controllers should warn their users when this occurs, unless they happen to know that the application using Tor is in fact doing so correctly (e.g., because it is part of a distributed bundle).} SOCKS_UNKNOWN_PROTOCOL "DATA=string" A connection was made to Tor's SOCKS port that tried to use it for something other than the SOCKS protocol. Perhaps the user is using Tor as an HTTP proxy? The DATA is the first few characters sent to Tor on the SOCKS port. {Controllers may want to warn their users when this occurs: it indicates a misconfigured application.} SOCKS_BAD_HOSTNAME "HOSTNAME=QuotedString" Some application gave us a funny-looking hostname. Perhaps it is broken? In any case it won't work with Tor and the user should know. {Controllers may want to warn their users when this occurs: it usually indicates a misconfigured application.} Actions for STATUS_SERVER can be as follows: EXTERNAL_ADDRESS "ADDRESS=IP" "HOSTNAME=NAME" "METHOD=CONFIGURED/DIRSERV/RESOLVED/INTERFACE/GETHOSTNAME" Our best idea for our externally visible IP has changed to 'IP'. If 'HOSTNAME' is present, we got the new IP by resolving 'NAME'. If the method is 'CONFIGURED', the IP was given verbatim as a configuration option. If the method is 'RESOLVED', we resolved the Address configuration option to get the IP. If the method is 'GETHOSTNAME', we resolved our hostname to get the IP. If the method is 'INTERFACE', we got the address of one of our network interfaces to get the IP. If the method is 'DIRSERV', a directory server told us a guess for what our IP might be. {Controllers may want to record this info and display it to the user.} CHECKING_REACHABILITY "ORADDRESS=IP:port" "DIRADDRESS=IP:port" We're going to start testing the reachability of our external OR port or directory port. {This event could effect the controller's idea of server status, but the controller should not interrupt the user to tell them so.} REACHABILITY_SUCCEEDED "ORADDRESS=IP:port" "DIRADDRESS=IP:port" We successfully verified the reachability of our external OR port or directory port. {This event could effect the controller's idea of server status, but the controller should not interrupt the user to tell them so.} GOOD_SERVER_DESCRIPTOR We successfully uploaded our server descriptor to each of the directory authorities, with no complaints. {This event could effect the controller's idea of server status, but the controller should not interrupt the user to tell them so.} NAMESERVER_STATUS "NS=addr" "STATUS=" "UP" / "DOWN" "ERR=" message One of our nameservers has changed status. // actually notice {This event could effect the controller's idea of server status, but the controller should not interrupt the user to tell them so.} NAMESERVER_ALL_DOWN All of our nameservers have gone down. {This is a problem; if it happens often without the nameservers coming up again, the user needs to configure more or better nameservers.} DNS_HIJACKED Our DNS provider is providing an address when it should be saying "NOTFOUND"; Tor will treat the address as a synonym for "NOTFOUND". {This is an annoyance; controllers may want to tell admins that their DNS provider is not to be trusted.} DNS_USELESS Our DNS provider is giving a hijacked address instead of well-known websites; Tor will not try to be an exit node. {Controllers could warn the admin if the server is running as an exit server: the admin needs to configure a good DNS server. Alternatively, this happens a lot in some restrictive environments (hotels, universities, coffeeshops) when the user hasn't registered.} BAD_SERVER_DESCRIPTOR "DIRAUTH=addr:port" "REASON=string" A directory authority rejected our descriptor. Possible reasons include malformed descriptors, incorrect keys, highly skewed clocks, and so on. {Controllers should warn the admin, and try to cope if they can.} ACCEPTED_SERVER_DESCRIPTOR "DIRAUTH=addr:port" A single directory authority accepted our descriptor. // actually notice {This event could effect the controller's idea of server status, but the controller should not interrupt the user to tell them so.} REACHABILITY_FAILED "ORADDRESS=IP:port" "DIRADDRESS=IP:port" We failed to connect to our external OR port or directory port successfully. {This event could effect the controller's idea of server status. The controller should warn the admin and suggest reasonable steps to take.} 4.1.11. Our set of guard nodes has changed Syntax: "650" SP "GUARDS" SP Type SP Name SP Status ... CRLF Type = "ENTRY" Name = The (possibly verbose) nickname of the guard affected. Status = "NEW" | "UP" | "DOWN" | "BAD" | "GOOD" | "DROPPED" [explain states. XXX] 4.1.12. Network status has changed Syntax: "650" "+" "NS" CRLF 1*NetworkStatus "." CRLF [First added in 0.1.2.3-alpha] 5. Implementation notes 5.1. Authentication By default, the current Tor implementation trusts all local users. If the 'CookieAuthentication' option is true, Tor writes a "magic cookie" file named "control_auth_cookie" into its data directory. To authenticate, the controller must send the contents of this file, encoded in hexadecimal. If the 'HashedControlPassword' option is set, it must contain the salted hash of a secret password. The salted hash is computed according to the S2K algorithm in RFC 2440 (OpenPGP), and prefixed with the s2k specifier. This is then encoded in hexadecimal, prefixed by the indicator sequence "16:". Thus, for example, the password 'foo' could encode to: 16:660537E3E1CD49996044A3BF558097A981F539FEA2F9DA662B4626C1C2 ++++++++++++++++**^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ salt hashed value indicator You can generate the salt of a password by calling 'tor --hash-password <password>' or by using the example code in the Python and Java controller libraries. To authenticate under this scheme, the controller sends Tor the original secret that was used to generate the password. 5.2. Don't let the buffer get too big. If you ask for lots of events, and 16MB of them queue up on the buffer, the Tor process will close the socket. 5.3. Backward compatibility with v0 control protocol. For backward compatibility with the "version 0" control protocol, Tor checks whether the third octet the first command is zero. If it is, Tor assumes that version 0 is in use. This feature is deprecated, and will be removed in the 0.1.3.x Tor development series. In order to detect which version of the protocol is supported controllers should send the sequence [00 00 0D 0A]. This is a valid and unrecognized command in both protocol versions, and implementations can detect which error they have received.