1 The server uses a protocol provided by libassuan to communicate with a client.
2 An OK response is returned when a command succeeds or ERR along with an error
3 code and description, if not. When a command requests data for retrieval
4 (e.g., GET) the output is prefixed with D then a single SPACE then the actual
5 data followed by an OK response if successful. Read the libassuan docs for
6 more info about the protocol.
12 OPEN <filename> [<key>]
13 Opens <filename> using <key>. If file is not found on the file-system, then
14 a new document will be created. If the file is found, it is looked for in
15 the file cache for an existing key. When found, the existing key will be
16 used for decryption. When not found, pinentry(1) will be used to retrieve
17 the key (see OPTIONS below). You can also open another file using the
22 Writes the XML document to disk. The file written to is the file that was
23 opened using the OPEN command. If <key> is not specified then the
24 currently cached key will be used. If the file is a new file or the file
25 isn't found in the file cache, <key> may be used. If <key> is not
26 specified then pinentry(1) will be used to retrieve the key (see OPTIONS
29 When the SAVE command is sent and a key is found in the file cache, the
30 cached key will be used. To reset the key to a new value, send the
31 CLEARCACHE command followed by the filename, then send the SAVE command to
36 An OK response is returned if the specified file is in the file cache.
39 CLEARCACHE [<filename>]
40 Clears a file cache entry. This will forget the timeout and key for all or
44 CACHETIMEOUT <seconds> <filename>
45 Specify the number of seconds the specified file will be cached. -1 will
46 keep the cache entry forever, 0 will require the key each time the OPEN or
47 SAVE commands are used. Also see the "cache_timeout" configuration option.
50 LIST [[!]element[<TAB>[!]element[...]]]
51 If no element path is given then a list of root elements is returned with
52 the data response code. If given, then all reachable elements for the
53 specified element path are returned. Each element in the path is prefixed
54 with the literal '!' character when the element contains no "target"
55 attribute (See THE TARGET ATTRIBUTE below).
57 If only a single element is specified and without the literal '!' prefix,
58 both the literal element tree and the element target (if any) tree will be
62 REALPATH [!]element[<TAB>[!]element[...]]
63 Resolves all "target" attributes of the specified element path and returns
64 the result with a data response.
67 STORE [!]element[[<TAB>[!]element[...]]<TAB>[content]]
68 Creates a new element tree or modifies the content of an existing element
69 path. If only a single element is specified, a new root element is
70 created. Otherwise, elements are TAB delimited and the content will be set
71 to the last TAB delimited argument. If no content is specified after the
72 last TAB then the content for the last specified element will be removed
73 or the content will be empty when creating a new element.
75 The only restriction of element names is that they not begin with a
76 punctuation character (the literal '!' character is an exception) or digit
77 and not contain any whitespace. There is no whitespace between the TAB
78 delimited elements. It is recommended that the value be base 64 encoded to
79 prevent libXML and pwmd parsing errors.
81 PWMD reads the element path from the client via the Assuan INQUIRE
82 protocol response. The STORE command is sent by itself without arguments,
83 then the server responds with INQUIRE. The client then sends the element
84 path prefixed by a "D " data response. When finished, the client
85 sends "END" on an empty line. This is needed so an element path and value
86 can be more than 1000 bytes long, the Assuan protocol line limit.
89 DELETE [!]element[<TAB>[!]element[...]]
90 Removes an element tree from the specified element path.
93 GET [!]element[<TAB>[!]element[...]]
94 Retrieves the content of the specified element path. The data is returned
98 ATTR SET|GET|DELETE|LIST [<attribute>] [!]<arg1> [!][arg2]
99 ATTR SET attribute [!]element[<TAB>[!]element[...]] attribute_value
100 Stores or updates an attribute value to an element path.
102 ATTR DELETE attribute [!]element[<TAB>[!]element[...]]
103 Removes an attribute from an element path.
105 ATTR LIST [!]element[<TAB>[!]element[...]]
106 Gets a list of attributes from an element path.
108 ATTR GET attribute [!]element[<TAB>[!]element[...]]
109 Gets the value of an attribute from an element path.
111 The "name" attribute (case sensitive) cannot be removed with ATTR DELETE
112 if the element path is only a root element. Although it can be SET to
113 change the root element name.
115 Also see THE TARGET ATTRIBUTE below.
119 Shows the in memory XML document with indenting.
122 GETCONFIG <parameter>
123 Returns the value of a pwmd configuration variable with a data response.
124 If no file is open then the default value will be returned. The "key" and
125 "key_file" variables are ignored.
129 Sets an option NAME to VALUE. See OPTIONS below.
133 Closes the connection. Use the SAVE command before this command as any
134 changes will be lost.
137 If a command fails then the ERR response is returned followed by a protocol
138 error code and description. See src/pwmd_error.h or libpwmd/libpwmd.h for
144 Commands that require a key that is neither cached or specified will use
145 pinentry(1) to retrieve the key. Pinentry options can be set with the OPTION
146 command followed by the option name and value. Below are the available
149 NAME VALUE Description
150 ---------|----------|----------------------------------------------------
151 PINENTRY 0|1 When 0, disable use of pinentry. The default is 1.
152 PATH <string> Full path to the pinentry binary. The default is
153 specified at compile time (/usr/bin/pinentry).
154 TTYNAME <string> Same as the --ttyname option to pinentry(1).
155 TTYTYPE <string> Same as the --ttytype option to pinentry(1).
156 DISPLAY <string> Same as the --display option to pinentry(1).
157 TITLE <string> Sets the title string of the dialog.
158 PROMPT <string> Sets the prompt string of the dialog.
159 DESC <string> Sets the error or description string of the dialog.
161 When pinentry is used with the SAVE command the key will be asked for
162 confirmation. If the confirmation fails, the process is started over again
163 until either the keys match or until Cancel is selected. The OPEN command will
164 only ask for the key once without retrying on failure. It is up to the client
165 to retry the OPEN command. Empty keys are allowed.
167 There is also a CLIENT option that contains other sub-options. The format is
168 OPTION CLIENT NAME=VALUE, where NAME is one of:
170 NAME VALUE Description
171 ---------|----------|----------------------------------------------------
172 NAME <string> Associates the thread ID of the connection with the
173 specified textual representation. Useful for
174 debugging log messages.
179 Some commands send a status message to the client when successful or as a
180 progress indicator. Status messages begin with a KEYWORD (see below) followed
181 by the status description. What messages are sent, and how often, depend on
182 configuration settings:
185 --------------------------------
205 KEYWORD OUTPUT FORMAT
206 ---------------------------------
207 CACHE <slots used> <slots available>
208 ENCRYPT <iterations so far>
209 DECRYPT <iterations so far>
210 COMPRESS <bytes so far> <total bytes>
211 DECOMPRESS <bytes so far> <total bytes>
212 LOCKED When another thread owns the file/key cache lock,
213 this is sent once and the thread blocks until the
214 lock can be obtained and the command completes.
215 KEEPALIVE Sent the after every configured amount of seconds.
216 This lets the client know that the connection is still
217 active for commands that take a while to complete.
222 There is a special attribute "target" (case sensitive) that can be set with
223 ATTR SET. The value of this attribute is an element path somewhere else in the
226 ATTR SET target [!]element[<TAB>[!]element[..]] [!]element[<TAB>[!]element[..]]
227 arg1^^^^^^^^^^^^^^^^^^^^^^^^ arg2^^^^^^^^^^^^^^^^^^^^^^^^
229 If the element path of the "target" attribute (arg1) doesn't exist, it is
230 created. This is the only time the ATTR command will create elements.
232 When a protocol command requests <arg1> as the element path, the remaining
233 elements after the element with the "target" attribute will be appended to
234 <arg2>. This is useful if you have elements that share the same data. If the
235 target is modified, the other elements "pointing" to the target will have the
236 same content. To get the real or literal element and ignore any "target"
237 attributes, prefix an element with a '!' character. Here's an example:
241 C> D host1<TAB>username<TAB>original username
246 C> D host2<TAB>smtp<TAB>username<TAB>someuser
249 C> ATTR SET target host1<TAB>username host2<TAB>smtp<TAB>username
252 Now host1's "target" attribute will be used:
254 C> GET host1<TAB>username
258 If you want host1's username, prefix the element of the "target" attribute
261 C> GET host1<TAB>!username
262 S> D original username
265 The target value (arg2) element can also have a "target" attribute:
267 C> ATTR SET target new_account host1
269 C> GET new_account<TAB>username
273 The value of the "target" attribute may also be prefixed with a '!' to set the
274 target to the actual element path and not a target of the element path:
276 C> ATTR DELETE target !new_account
278 C> ATTR SET target new_account<TAB>username host1<TAB>!username
280 C> GET new_account<TAB>username
281 S> D original username
284 The "target" attribute is considered for all commands that support an element
285 path. If the target element has been renamed or deleted afterwards, the
288 Clients should be careful of creating target loops. See the "recursion_depth"
289 configuration parameter for details.
292 XML DOCUMENT STRUCTURE
293 ----------------------
294 When importing an XML data file with the -I command line option, the document
295 should have the following DTD:
297 <?xml version="1.0"?>
299 <!ELEMENT accounts (account*)>
300 <!ATTLIST account name CDATA #REQUIRED>
303 "accounts" is the document root element while each root element mentioned in
304 the protocol commands use the "account" element. So if you have a root element
305 "isp" to be shown with the LIST command ("LIST isp"), the document structure
314 The DUMP command can be useful to show the current document structure.
319 The key cache is protected with a mutex and is locked with each access. Each
320 cache entry also contains a mutex for the opened file and a reference count
321 which is adjusted each time a client connects or disconnects. This allows
322 client A to issue commands that aren't related to the file opened by client B.
323 The refcount is needed to prevent the mutex being overwritten when the entry
324 needs to be reset (CACHETIMEOUT for example) and there are any client
327 The client_thread() uses an event to wait for the client FD to become ready
328 for reading. When ready, it uses the libassuan assuan_process_next() function
329 to prevent blocking. This allows for the keepalive_thread() and any signals
330 send to client_thread() to continue to work and lets the Pth scheduler let
331 other (client) threads do their work too.
333 The cleanup_thread() is a loop that sleeps at some interval and is responsible
334 for freeing the resources of the client after the associated client_thread()
335 terminates or exits. How it determines if the client exited is done with the
336 PTH_UNTIL_TID_DEAD event; it checks a list of recorded connections for that
339 When a key is required for the OPEN or SAVE commands, and OPTION PINENTRY=1,
340 pinentry(1) is used to retrieve the key. This is done by creating a pipe()
341 with the client_thread(), then pth_fork()'s the pinentry process which will
342 write the key or error to the pipe that client_thread() will read from. After
343 the read, the pinentry should have exited and client_thread() calls the
344 finalization function for the command that used pinentry.
347 ------------- ---------------
348 ----------[server_loop]-_-_-_-[socket_thread]
349 | ------------- ---------------
350 | not joinable : | accept()
351 | --------------------- ---------------
352 | [adjust_timer_thread] [client_thread]<------------=====
353 | --------------------- --------------- | | | =
355 |---| : | | | | | | =
357 ---------------- : | | | | | | =
358 [cleanup_thread] ::::::::: | | | | | | =
359 ---------------- : | | --------- | | =
360 | pth_cancel() : | | [command] | | =
361 | ------------------ | | --------- | | = pipe()
362 |--------[keepalive_thread] | | | | | | =
363 ------------------ | | | --------- | =
367 | | |----[OPEN/SAVE] =
369 -------------------- : fork() =
370 [ command finalize ] ---------- =
371 -------------------- [pinentry]====
375 Questions, bugs or feature requests can be sent to
376 Ben Kibbey <bjk@luxsci.net>.