It is assumed the reader is familiar with bencoding, as described in the BitTorrent protocol specification at http://www.bittorrent.org/protocol.html Dictionary keys used below will be enclosed in quotation marks, these are used for clarity and are not part of the actual key. The IPC protocol is used to allow processes to control or retrieve information from a Transmission frontend, such as transmission-daemon or transmission-gtk. This communication is done over a unix-domain socket file, such as ~/.transmission/daemon/socket. In this document the Transmission frontend will be referred to as the server and the process connecting to it as the client. Once a client connects to the server's socket, messages may be exchanged until either end closes the connection. Messages contain an 32-bit payload length, encoded as 8 bytes of ASCII hexidecimal, followed by the payload. Upper, lower, or mixed case for the length are all accpetable and must be handled correctly. Payload lengths greater than 2^31 - 8 (ie: 2147483640) are not allowed. For version 1, the message payload is a bencoded dictionary, the valid keys and value formats for which are described below. Multiple keys may be used in one message. An example version 1 message: 0000000Ed4:porti9090ee For version 2 the message payload is a bencoded list containing a message id string followed by a bencoded value, the format of which is the same for version 1. The value may be followed by an optional bencoded integer, this is a message tag and is described in more detail below. An example version 2 message: 0000001El12:get-info-alll4:hashee The same message with a tag: 00000021l12:get-info-alll4:hashei5ee Once the connection is made both the client and server must send a version 1 style message (ie: the payload is a dictionary and may not contain a tag) with the dictionary key "version" and a value formatted as described below. The version should be the first but not necessarily only key in the dictionary. Any other keys should be ignored and not processed as messages. Neither the client nor the server should wait to receive a version message before sending one, it must be sent immediately. No other messages should be sent until the version is received. The version value should be a bencoded dictionary containing two keys, "max" and "min". These are the minimum and maximum supported protocol versions, respectively. Communication will take place using the highest protocol version supported by both the client and the server, and is not possible at all if there is no common version. A client may receive a version value that is an integer instead of a dictionary with "min" and "max" keys. This deprecated version format indicates the only version supported by the server. An example message containing minimum and maximum versions 1 and 2: 0000001Dd7:versiond3:mini1e3:maxi2eee Tagged messages, only supported in version 2, allow a client to tag a message with a positive non-zero integer. The server is then required to send a response to the message even if none would normally be required, and to tag the response with the same integer. When the server receives a tagged message it must send exactly one message back with the same tag. The client is allowed to use the same tag for multiple messages, even if a response to the first is not received before the second it sent. If a tagged message does not normally require a response then a "succeeded", "failed" or "not-supported" message will be sent back. An example tagged message and response: 00000010l5:startli8eei15ee 00000011l8:succeeded0:i15ee Some example sessions, including version handshake, are found at the end of this file. Dictionary keys are encoded in UTF-8 and case sensitive. Any character except a NUL (0x00) is valid. A server or client need not support every possible key and should silently ignore any that it does not understand. If a reference to a boolean is seen, it should be taken to mean an integer with a value of 0 representing false, 1 representing true, and any other value undefined. Individual torrents are identified by a unique integer. This integer is only valid for the current connection and may be invalid or refer to another torrent in a future connection. If a torrent is closed it's ID will never be reused to refer to another torrent for at least the duration of the connection. Negative integers or 0 are not valid IDs. A list of keys and the format of their values follows. Also listed is the minimum protocol version that the key may be used with. Key: "addfiles" Version: 1 Format: list of strings Example: 8:addfilesl21:/torrents/foo.torrent20:/home/me/bar.torrente Details: Each string is the absolute path to a torrent metainfo file for the server to add. Note that whether or not the torrent metainfo file is copied (allowing the original to be moved or deleted safely) is implementation dependent and may not currently be known or changed with this protocol. Key: "addfile-detailed" Version: 2 Format: dict Example: 16:addfile-detailedde Details: Dictionary containing information about a torrent for the server to add. Valid keys include: "file" string, filename of torrent metainfo file "data" string, contents of a torrent metainfo file "directory" string, directory for data files for the torrent "autostart" boolean, start the torrent automatically Either "file" or "data" is required, but both are not allowed. Key: "automap" Version: 2 Format: boolean Example: 7:automapi1e Details: Enable (1) or disable (0) automatic port mapping on the server. Other integer values will likely be treated as 1 but this shold not be relied upon. Key: "autostart" Version: 2 Format: boolean Example: 9:autostarti0e Details: Enable (1) or disable (0) automatic starting of new torrents added via "addfiles" message. Key: "directory" Version: 2 Format: string Example: 9:directory21:/home/roger/downloads Details: Set the default directory used for any torrents added in the future. Key: "downlimit" Version: 2 Format: int Example: 9:downlimiti100e Details: Set the server's download limit in kilobytes per second. Negative values are interpreted as no limit. Key: "failed" Version: 2 Format: string Example: 6:failed17:permission denied Details: Sent in response to a tagged message to indicate failure. Key: "get-automap" Version: 2 Format: value is ignored Example: 11:get-automap0: Details: Requests that an "automap" message be sent back. Key: "get-autostart" Version: 2 Format: value is ignored Example: 13:get-autostart0: Details: Requests that an "autostart" message be sent back. Key: "get-directory" Version: 2 Format: value is ignored Example: 13:get-directory Details: Requests that an "directory" message be sent back. Key: "get-downlimit" Version: 2 Format: value is ignored Example: 13:get-downlimit0: Details: Requests that a "downlimit" message be sent back. Key: "get-info" Version: 2 Format: dict with keys "id" and "type" for lists of ints and strings Example: 8:get-infod2:idli4ei7ei2ee4:typel4:hash4:nameee Details: Requests that the server send back an "info" message with info on all the torrent IDs in "id". The "type" key requests what info will be returned. See below for valid values to use here. Since the torrent ID is always included in an "info" message an empty or missing "type" key will cause only the ID to be returned. An "info" message will always be sent back, even if it is empty. Key: "get-info-all" Version: 2 Format: list of strings Example: 12:get-info-alll4:hash4:namee Details: Same as "getinfo" message with all torrent IDs specified. Key: "get-pex" Version: 2 Format: value is ignored Example: 7:get-pex0: Details: Requests that a "pex" message be sent back. Key: "get-port" Version: 2 Format: value is ignored Example: 8:get-port0: Details: Requests that a "port" message be sent back. Key: "get-status" Version: 2 Format: dict with keys "id" and "type" for lists of ints and strings Example: 10:get-statusd2:idli4ei7ei2ee4:typel4:hash4:nameee Details: Same as "get-info" message except status type strings are used instead and the server sends back a "status" message. Key: "get-status-all" Version: 2 Format: list of strings Example: 14:get-status-alll4:hash4:namee Details: Same as "get-status" message with all torrent IDs specified. Key: "get-supported" Version: 2 Format: list of strings Example: 13:get-supportedl6:lookup8:get-porte Details: Request that a "supported" message be returned with whichever of the given message keys are supported. Key: "get-uplimit" Version: 2 Format: value is ignored Example: 11:get-uplimit0: Details: Requests that an "uplimit" message be sent back. Key: "lookup" Version: 2 Format: list of strings Example: 6:lookupl40:0f16ea6965ee5133ea4dbb1e7f516e9fcf3d899ee Details: Request that the server send back an "info" message with "id" and "hash" keys for any torrents with the given hashes. Key: "info" Version: 2 Format: list of dictionaries Example: 4:infold2:idi3e4:name3:fooed2:idi9e4:name3:baree Details: A list containing information for several torrents. The dictionaries always contain at least an "id" key with the integer ID for the torrent, other possible values are listed below. Key: "noop" Version: 2 Format: value is ignored Example: 4:noop0: Details: This does nothing but keep the connection alive. With a tag it may be used as a ping. Key: "not-supported" Version: 2 Format: value is ignored Example: 13:not-supported0: Details: Sent in response to a tagged message to indicated that the message was not supported. Key: "pex" Version: 2 Format: boolean Example: 3:pexi0e Details: Enables or disables peer exchange. Key: "port" Version: 2 Format: int between 0 and 65535 Example: 4:porti9090e Details: Change the port the server uses to listen for incoming peer connections. Key: "quit" Version: 1 Format: value is ignored Example: 4:quit0: Details: Cause the server to quit. Key: "remove" Version: 2 Format: list of torrent ID ints Example: 5:removeli3ei8ei6ee Details: Stop and remove the specified torrents. Note that whether or not the downloaded data or the original torrent files will be removed is implementation dependent and may not currently be known or changed with this protocol. If a saved copy of the torrent file has been made then it will always be deleted. Key: "remove-all" Version: 2 Format: value is ignored Example: 10:remove-all0: Details: Like "remove" with all torrent IDs specified. Key: "start" Version: 2 Format: list of torrent ID ints Example: 5:startli3ei8ei6ee Details: List of torrent IDs to start. Key: "start-all" Version: 2 Format: value is ignored Example: 9:start-all0: Details: Start all torrents. Key: "status" Version: 2 Format: list of dictionaries Example: 4:infold2:idi3e4:name3:fooed2:idi9e4:name3:baree Details: Same as "info" message except status type keys are used. Key: "stop" Version: 2 Format: list of torrent ID ints Example: 4:stopli3ei8ei6ee Details: List of torrent IDs to stop. Key: "stop-all" Version: 2 Format: value is ignored Example: 8:stop-all0: Details: Stop all torrents. Key: "succeeded" Version: 2 Format: value is ignored Example: 8:succeeded0: Details: This is used to indicate that a tagged message was processed successfully. Key: "supported" Version: 2 Format: list of strings Example: 9:supportedl6:lookupe Details: Sent in response to a "get-supported" message, indicates that the given messages ate supported. Key: "uplimit" Version: 2 Format: int Example: 7:uplimiti20e Details: Set the server's upload limit in kilobytes per second. Negative values are interpreted as no limit. Info types for "get-info" and "info" messages. The only type for which support is mandatory is "id". "id" integer, torrent's ID for this connection "hash" SHA-1 info hash as a 40-char hex string "name" string, torrent name "path" string, path to .torrent file "saved" boolean, true if a copy of this torrent was saved "private" boolean, true if the torrent is private "trackers" a list of lists of dictionaries containing tracker info: "address" string, hostname or ip address of tracker "port" integer, port for tracker "announce" string, announce url on tracker "scrape" string, scrape url on tracker, may be absent "comment" string, comment from torrent file "creator" string, creator of torrent file "date" integer, date of torrent creation (unix time_t format) "size" integer, total size of all files in bytes "files" list of dictionaries for the files in this torrent: "name" string, name of file "size" integer, size of file in bytes Status types for "get-status" and "status" messages. The only type for which support is mandatory is "id". "completed" integer, bytes of data downloaded and verified "download-speed" integer, download speed in bytes per second "download-total" integer, total bytes downloaded so far "error" string, one of the following: "assert" something happened that shouldn't "io-parent" missing parent directory "io-permissions" filesystem permission error "io-space" not enough free space in filesystem "io-resource" insufficient resources "io-other" other filesystem i/o error "tracker-error" tracker returned error message "tracker-warning" tracker returned warning message "other" other error zero-length or missing string indicates no error "error-message" string, printable error message "eta" integer, estimated seconds until downloading is finished "id" integer, torrent's ID for this connection "peers-downloading" integer, peers downloading from us "peers-from" dict with the following int keys, peer connection sources: "incoming" peers connected to our listening port "tracker" peers discovered from tracker "cache" peers retrieved from on-disk cache "pex" peers discovered via peer exchange "peers-total" integer, total connected peers "peers-uploading" integer, peers uploading to us "running" boolean, false if torrent is stopped or stopping "state" string, one of the following: "checking" performing hash check on file data "downloading" downloading file data "seeding" seeding file data to peers "stopping" contacting tracker to send 'stopped' event "paused" torrent is not active "swarm-speed" integer, swarm speed in bytes per second "tracker" dict with the following keys, current active tracker "address" string, hostname or ip address of tracker "port" integer, port for tracker "announce" string, tracker announce url "scrape" string, tracker scrape url, may be absent "scrape-completed" integer, total completed peers as reported by tracker "scrape-leechers" integer, current leechers as reported by tracker "scrape-seeders" integer, current, seeders as reported by tracker "upload-speed" integer, upload speed in bytes per second "upload-total" integer, total bytes uploaded so far Examples: Data from the client to the server is prefixed with >>> and from server to client with <<<. These prefixes and newlines are added for clarity, they are not actually sent over the socket. Quit the server. Note that this is a version 1 client and so version 1 messages are used. The value for the quit message here is i0e instead of 0: as used above, however since it it unused any value is allowed. >>> 0000001Dd7:versiond3:mini1e3:maxi1eee <<< 0000001Dd7:versiond3:mini1e3:maxi2eee >>> 0000000Bd4:quiti0ee Pause all torrents and disable automapping. Note the server happens to have sendt it's version before the client. <<< 0000001Dd7:versiond3:mini1e3:maxi2eee >>> 0000001Dd7:versiond3:mini1e3:maxi2eee >>> 0000000El8:stop-all0:e Change upload and download limits with tagged responses. Note that the server is allowed to return responses out of order, even when the messages are not tagged. >>> 0000001Dd7:versiond3:mini1e3:maxi2eee <<< 0000001Dd7:versiond3:mini1e3:maxi2eee >>> 00000017l9:downlimiti100ei100el >>> 00000017l9:downlimiti100ei101el <<< 00000014l8:succeeded0:i101el <<< 00000014l8:succeeded0:i100el