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config.pod 9.7 KB

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  1. =pod
  2. =for comment openssl_manual_section:5
  3. =head1 NAME
  4. config - OpenSSL CONF library configuration files
  5. =head1 DESCRIPTION
  6. The OpenSSL CONF library can be used to read configuration files.
  7. It is used for the OpenSSL master configuration file B<openssl.cnf>
  8. and in a few other places like B<SPKAC> files and certificate extension
  9. files for the B<x509> utility. OpenSSL applications can also use the
  10. CONF library for their own purposes.
  11. A configuration file is divided into a number of sections. Each section
  12. starts with a line B<[ section_name ]> and ends when a new section is
  13. started or end of file is reached. A section name can consist of
  14. alphanumeric characters and underscores.
  15. The first section of a configuration file is special and is referred
  16. to as the B<default> section this is usually unnamed and is from the
  17. start of file until the first named section. When a name is being looked up
  18. it is first looked up in a named section (if any) and then the
  19. default section.
  20. The environment is mapped onto a section called B<ENV>.
  21. Comments can be included by preceding them with the B<#> character
  22. Each section in a configuration file consists of a number of name and
  23. value pairs of the form B<name=value>
  24. The B<name> string can contain any alphanumeric characters as well as
  25. a few punctuation symbols such as B<.> B<,> B<;> and B<_>.
  26. The B<value> string consists of the string following the B<=> character
  27. until end of line with any leading and trailing white space removed.
  28. The value string undergoes variable expansion. This can be done by
  29. including the form B<$var> or B<${var}>: this will substitute the value
  30. of the named variable in the current section. It is also possible to
  31. substitute a value from another section using the syntax B<$section::name>
  32. or B<${section::name}>. By using the form B<$ENV::name> environment
  33. variables can be substituted. It is also possible to assign values to
  34. environment variables by using the name B<ENV::name>, this will work
  35. if the program looks up environment variables using the B<CONF> library
  36. instead of calling B<getenv()> directly.
  37. It is possible to escape certain characters by using any kind of quote
  38. or the B<\> character. By making the last character of a line a B<\>
  39. a B<value> string can be spread across multiple lines. In addition
  40. the sequences B<\n>, B<\r>, B<\b> and B<\t> are recognized.
  41. =head1 OPENSSL LIBRARY CONFIGURATION
  42. In OpenSSL 0.9.7 and later applications can automatically configure certain
  43. aspects of OpenSSL using the master OpenSSL configuration file, or optionally
  44. an alternative configuration file. The B<openssl> utility includes this
  45. functionality: any sub command uses the master OpenSSL configuration file
  46. unless an option is used in the sub command to use an alternative configuration
  47. file.
  48. To enable library configuration the default section needs to contain an
  49. appropriate line which points to the main configuration section. The default
  50. name is B<openssl_conf> which is used by the B<openssl> utility. Other
  51. applications may use an alternative name such as B<myapplicaton_conf>.
  52. The configuration section should consist of a set of name value pairs which
  53. contain specific module configuration information. The B<name> represents
  54. the name of the I<configuration module> the meaning of the B<value> is
  55. module specific: it may, for example, represent a further configuration
  56. section containing configuration module specific information. E.g.
  57. openssl_conf = openssl_init
  58. [openssl_init]
  59. oid_section = new_oids
  60. engines = engine_section
  61. [new_oids]
  62. ... new oids here ...
  63. [engine_section]
  64. ... engine stuff here ...
  65. Currently there are two configuration modules. One for ASN1 objects another
  66. for ENGINE configuration.
  67. =head2 ASN1 OBJECT CONFIGURATION MODULE
  68. This module has the name B<oid_section>. The value of this variable points
  69. to a section containing name value pairs of OIDs: the name is the OID short
  70. and long name, the value is the numerical form of the OID. Although some of
  71. the B<openssl> utility sub commands already have their own ASN1 OBJECT section
  72. functionality not all do. By using the ASN1 OBJECT configuration module
  73. B<all> the B<openssl> utility sub commands can see the new objects as well
  74. as any compliant applications. For example:
  75. [new_oids]
  76. some_new_oid = 1.2.3.4
  77. some_other_oid = 1.2.3.5
  78. In OpenSSL 0.9.8 it is also possible to set the value to the long name followed
  79. by a comma and the numerical OID form. For example:
  80. shortName = some object long name, 1.2.3.4
  81. =head2 ENGINE CONFIGURATION MODULE
  82. This ENGINE configuration module has the name B<engines>. The value of this
  83. variable points to a section containing further ENGINE configuration
  84. information.
  85. The section pointed to by B<engines> is a table of engine names (though see
  86. B<engine_id> below) and further sections containing configuration informations
  87. specific to each ENGINE.
  88. Each ENGINE specific section is used to set default algorithms, load
  89. dynamic, perform initialization and send ctrls. The actual operation performed
  90. depends on the I<command> name which is the name of the name value pair. The
  91. currently supported commands are listed below.
  92. For example:
  93. [engine_section]
  94. # Configure ENGINE named "foo"
  95. foo = foo_section
  96. # Configure ENGINE named "bar"
  97. bar = bar_section
  98. [foo_section]
  99. ... foo ENGINE specific commands ...
  100. [bar_section]
  101. ... "bar" ENGINE specific commands ...
  102. The command B<engine_id> is used to give the ENGINE name. If used this
  103. command must be first. For example:
  104. [engine_section]
  105. # This would normally handle an ENGINE named "foo"
  106. foo = foo_section
  107. [foo_section]
  108. # Override default name and use "myfoo" instead.
  109. engine_id = myfoo
  110. The command B<dynamic_path> loads and adds an ENGINE from the given path. It
  111. is equivalent to sending the ctrls B<SO_PATH> with the path argument followed
  112. by B<LIST_ADD> with value 2 and B<LOAD> to the dynamic ENGINE. If this is
  113. not the required behaviour then alternative ctrls can be sent directly
  114. to the dynamic ENGINE using ctrl commands.
  115. The command B<init> determines whether to initialize the ENGINE. If the value
  116. is B<0> the ENGINE will not be initialized, if B<1> and attempt it made to
  117. initialized the ENGINE immediately. If the B<init> command is not present
  118. then an attempt will be made to initialize the ENGINE after all commands in
  119. its section have been processed.
  120. The command B<default_algorithms> sets the default algorithms an ENGINE will
  121. supply using the functions B<ENGINE_set_default_string()>
  122. If the name matches none of the above command names it is assumed to be a
  123. ctrl command which is sent to the ENGINE. The value of the command is the
  124. argument to the ctrl command. If the value is the string B<EMPTY> then no
  125. value is sent to the command.
  126. For example:
  127. [engine_section]
  128. # Configure ENGINE named "foo"
  129. foo = foo_section
  130. [foo_section]
  131. # Load engine from DSO
  132. dynamic_path = /some/path/fooengine.so
  133. # A foo specific ctrl.
  134. some_ctrl = some_value
  135. # Another ctrl that doesn't take a value.
  136. other_ctrl = EMPTY
  137. # Supply all default algorithms
  138. default_algorithms = ALL
  139. =head1 NOTES
  140. If a configuration file attempts to expand a variable that doesn't exist
  141. then an error is flagged and the file will not load. This can happen
  142. if an attempt is made to expand an environment variable that doesn't
  143. exist. For example in a previous version of OpenSSL the default OpenSSL
  144. master configuration file used the value of B<HOME> which may not be
  145. defined on non Unix systems and would cause an error.
  146. This can be worked around by including a B<default> section to provide
  147. a default value: then if the environment lookup fails the default value
  148. will be used instead. For this to work properly the default value must
  149. be defined earlier in the configuration file than the expansion. See
  150. the B<EXAMPLES> section for an example of how to do this.
  151. If the same variable exists in the same section then all but the last
  152. value will be silently ignored. In certain circumstances such as with
  153. DNs the same field may occur multiple times. This is usually worked
  154. around by ignoring any characters before an initial B<.> e.g.
  155. 1.OU="My first OU"
  156. 2.OU="My Second OU"
  157. =head1 EXAMPLES
  158. Here is a sample configuration file using some of the features
  159. mentioned above.
  160. # This is the default section.
  161. HOME=/temp
  162. RANDFILE= ${ENV::HOME}/.rnd
  163. configdir=$ENV::HOME/config
  164. [ section_one ]
  165. # We are now in section one.
  166. # Quotes permit leading and trailing whitespace
  167. any = " any variable name "
  168. other = A string that can \
  169. cover several lines \
  170. by including \\ characters
  171. message = Hello World\n
  172. [ section_two ]
  173. greeting = $section_one::message
  174. This next example shows how to expand environment variables safely.
  175. Suppose you want a variable called B<tmpfile> to refer to a
  176. temporary filename. The directory it is placed in can determined by
  177. the the B<TEMP> or B<TMP> environment variables but they may not be
  178. set to any value at all. If you just include the environment variable
  179. names and the variable doesn't exist then this will cause an error when
  180. an attempt is made to load the configuration file. By making use of the
  181. default section both values can be looked up with B<TEMP> taking
  182. priority and B</tmp> used if neither is defined:
  183. TMP=/tmp
  184. # The above value is used if TMP isn't in the environment
  185. TEMP=$ENV::TMP
  186. # The above value is used if TEMP isn't in the environment
  187. tmpfile=${ENV::TEMP}/tmp.filename
  188. =head1 BUGS
  189. Currently there is no way to include characters using the octal B<\nnn>
  190. form. Strings are all null terminated so nulls cannot form part of
  191. the value.
  192. The escaping isn't quite right: if you want to use sequences like B<\n>
  193. you can't use any quote escaping on the same line.
  194. Files are loaded in a single pass. This means that an variable expansion
  195. will only work if the variables referenced are defined earlier in the
  196. file.
  197. =head1 SEE ALSO
  198. L<x509(1)|x509(1)>, L<req(1)|req(1)>, L<ca(1)|ca(1)>
  199. =cut