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-rw-r--r--pythonmod/doc/examples/example4.rst180
1 files changed, 97 insertions, 83 deletions
diff --git a/pythonmod/doc/examples/example4.rst b/pythonmod/doc/examples/example4.rst
index b665351e84ec..3382109903aa 100644
--- a/pythonmod/doc/examples/example4.rst
+++ b/pythonmod/doc/examples/example4.rst
@@ -1,15 +1,19 @@
DNS-based language dictionary
-===============================
+=============================
This example shows how to create a simple language dictionary based on **DNS**
-service within 15 minutes. The translation will be performed using TXT resource records.
+service within 15 minutes. The translation will be performed using TXT resource
+records.
Key parts
------------
+---------
Initialization
-~~~~~~~~~~~~~~~~~~~~~~~
-On **init()** module loads dictionary from a text file containing records in ``word [tab] translation`` format.
+~~~~~~~~~~~~~~
+
+On **init()** module loads dictionary from a text file containing records in
+``word [tab] translation`` format.
+
::
def init(id, cfg):
@@ -20,11 +24,14 @@ On **init()** module loads dictionary from a text file containing records in ``w
The suitable file can be found at http://slovnik.zcu.cz
DNS query and word lookup
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~
-Let's define the following format od DNS queries: ``word1[.]word2[.] ... wordN[.]{en,cs}[._dict_.cz.]``.
+Let's define the following format od DNS queries:
+``word1[.]word2[.] ... wordN[.]{en,cs}[._dict_.cz.]``.
Word lookup is done by simple ``dict`` lookup from broken DNS request.
-Query name is divided into a list of labels. This list is accessible as qname_list attribute.
+Query name is divided into a list of labels. This list is accessible as
+``qname_list`` attribute.
+
::
aword = ' '.join(qstate.qinfo.qname_list[0:-4]) #skip last four labels
@@ -37,35 +44,40 @@ Query name is divided into a list of labels. This list is accessible as qname_li
if (adict == "cs") and (aword in cz_dict):
words = cz_dict[aword] # CS -> EN
-In the first step, we get a string in the form: ``word1[space]word2[space]...word[space]``.
-In the second assignment, fourth label from the end is obtained. This label should contains *"cs"* or *"en"*.
-This label determines the direction of translation.
-
+In the first step, we get a string in the form:
+``word1[space]word2[space]...word[space]``.
+In the second assignment, fourth label from the end is obtained. This label
+should contains *"cs"* or *"en"*. This label determines the direction of
+translation.
Forming of a DNS reply
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~
DNS reply is formed only on valid match and added as TXT answer.
+
::
- msg = DNSMessage(qstate.qinfo.qname_str, RR_TYPE_TXT, RR_CLASS_IN, PKT_AA)
+ msg = DNSMessage(qstate.qinfo.qname_str, RR_TYPE_TXT, RR_CLASS_IN, PKT_AA)
- for w in words:
- msg.answer.append("%s 300 IN TXT \"%s\"" % (qstate.qinfo.qname_str, w.replace("\"", "\\\"")))
+ for w in words:
+ msg.answer.append("%s 300 IN TXT \"%s\"" % (qstate.qinfo.qname_str, w.replace("\"", "\\\"")))
- if not msg.set_return_msg(qstate):
- qstate.ext_state[id] = MODULE_ERROR
- return True
+ if not msg.set_return_msg(qstate):
+ qstate.ext_state[id] = MODULE_ERROR
+ return True
- qstate.return_rcode = RCODE_NOERROR
- qstate.ext_state[id] = MODULE_FINISHED
- return True
+ qstate.return_rcode = RCODE_NOERROR
+ qstate.ext_state[id] = MODULE_FINISHED
+ return True
-In the first step, a :class:`DNSMessage` instance is created for a given query *(type TXT)*.
+In the first step, a :class:`DNSMessage` instance is created for a given query
+*(type TXT)*.
The fourth argument specifies the flags *(authoritative answer)*.
-In the second step, we append TXT records containing the translation *(on the right side of RR)*.
+In the second step, we append TXT records containing the translation *(on the
+right side of RR)*.
Then, the response is finished and ``qstate.return_msg`` contains new response.
-If no error, the module sets :attr:`module_qstate.return_rcode` and :attr:`module_qstate.ext_state`.
+If no error, the module sets :attr:`module_qstate.return_rcode` and
+:attr:`module_qstate.ext_state`.
**Steps:**
@@ -82,80 +94,82 @@ Run the Unbound server:
In case you use own configuration file, don't forget to enable Python module::
- module-config: "validator python iterator"
+ module-config: "validator python iterator"
and use valid script path::
- python-script: "./examples/dict.py"
+ python-script: "./examples/dict.py"
The translation from english word *"a bar fly"* to Czech can be done by doing:
``>>>dig TXT @127.0.0.1 a.bar.fly.en._dict_.cz``
-::
+::
+
+ ; (1 server found)
+ ;; global options: printcmd
+ ;; Got answer:
+ ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48691
+ ;; flags: aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
+
+ ;; QUESTION SECTION:
+ ;a.bar.fly.en._dict_.cz. IN TXT
+
+ ;; ANSWER SECTION:
+ a.bar.fly.en._dict_.cz. 300 IN TXT "barov\253 povale\232"
+
+ ;; Query time: 5 msec
+ ;; SERVER: 127.0.0.1#53(127.0.0.1)
+ ;; WHEN: Mon Jan 01 17:44:18 2009
+ ;; MSG SIZE rcvd: 67
- ; (1 server found)
- ;; global options: printcmd
- ;; Got answer:
- ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48691
- ;; flags: aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
-
- ;; QUESTION SECTION:
- ;a.bar.fly.en._dict_.cz. IN TXT
-
- ;; ANSWER SECTION:
- a.bar.fly.en._dict_.cz. 300 IN TXT "barov\253 povale\232"
-
- ;; Query time: 5 msec
- ;; SERVER: 127.0.0.1#53(127.0.0.1)
- ;; WHEN: Mon Jan 01 17:44:18 2009
- ;; MSG SIZE rcvd: 67
-
``>>>dig TXT @127.0.0.1 nic.cs._dict_.cz``
+
::
- ; <<>> DiG 9.5.0-P2 <<>> TXT @127.0.0.1 nic.cs._dict_.cz
- ; (1 server found)
- ;; global options: printcmd
- ;; Got answer:
- ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 58710
- ;; flags: aa rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 0
-
- ;; QUESTION SECTION:
- ;nic.cs._dict_.cz. IN TXT
-
- ;; ANSWER SECTION:
- nic.cs._dict_.cz. 300 IN TXT "aught"
- nic.cs._dict_.cz. 300 IN TXT "naught"
- nic.cs._dict_.cz. 300 IN TXT "nihil"
- nic.cs._dict_.cz. 300 IN TXT "nix"
- nic.cs._dict_.cz. 300 IN TXT "nothing"
- nic.cs._dict_.cz. 300 IN TXT "zilch"
-
- ;; Query time: 0 msec
- ;; SERVER: 127.0.0.1#53(127.0.0.1)
- ;; WHEN: Mon Jan 01 17:45:39 2009
- ;; MSG SIZE rcvd: 143
-
-Proof that the unbound still works as resolver.
+ ; <<>> DiG 9.5.0-P2 <<>> TXT @127.0.0.1 nic.cs._dict_.cz
+ ; (1 server found)
+ ;; global options: printcmd
+ ;; Got answer:
+ ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 58710
+ ;; flags: aa rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 0
+
+ ;; QUESTION SECTION:
+ ;nic.cs._dict_.cz. IN TXT
+
+ ;; ANSWER SECTION:
+ nic.cs._dict_.cz. 300 IN TXT "aught"
+ nic.cs._dict_.cz. 300 IN TXT "naught"
+ nic.cs._dict_.cz. 300 IN TXT "nihil"
+ nic.cs._dict_.cz. 300 IN TXT "nix"
+ nic.cs._dict_.cz. 300 IN TXT "nothing"
+ nic.cs._dict_.cz. 300 IN TXT "zilch"
+
+ ;; Query time: 0 msec
+ ;; SERVER: 127.0.0.1#53(127.0.0.1)
+ ;; WHEN: Mon Jan 01 17:45:39 2009
+ ;; MSG SIZE rcvd: 143
+
+ Proof that the unbound still works as resolver.
``>>>dig A @127.0.0.1 www.nic.cz``
+
::
- ; (1 server found)
- ;; global options: printcmd
- ;; Got answer:
- ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19996
- ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 5
-
- ;; QUESTION SECTION:
- ;www.nic.cz. IN A
-
- ;; ANSWER SECTION:
- www.nic.cz. 1662 IN A 217.31.205.50
-
- ;; AUTHORITY SECTION:
- ...
+ ; (1 server found)
+ ;; global options: printcmd
+ ;; Got answer:
+ ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19996
+ ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 5
+
+ ;; QUESTION SECTION:
+ ;www.nic.cz. IN A
+
+ ;; ANSWER SECTION:
+ www.nic.cz. 1662 IN A 217.31.205.50
+
+ ;; AUTHORITY SECTION:
+ ...
Complete source code
--------------------
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-31 04:09:23 +0000