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2aed491c SS |
1 | package Guardian::Config; |
2 | use strict; | |
3 | use warnings; | |
4 | ||
5 | use Exporter qw(import); | |
6 | ||
7 | our @EXPORT_OK = qw(CheckConfig UseConfig); | |
8 | ||
9 | # The default config file which is used, if no one has been specified. | |
10 | my $configfile = "/etc/guardian/guardian.conf"; | |
11 | ||
12 | # The maximum amount of chars, which a line in the configfile is allowed to contain. | |
13 | my $maxlength = "64"; | |
14 | ||
15 | # Hash with default settings. They may be overwritten by settings of the config file. | |
16 | my %defaults = ( | |
17 | "LogLevel" => "info", | |
18 | "LogFacility" => "syslog", | |
19 | "BlockCount" => "3", | |
20 | "BlockTime" => "86400", | |
b3dd9bd0 | 21 | "FirewallEngine" => "none", |
2aed491c SS |
22 | ); |
23 | ||
24 | # | |
25 | ## UseConfig configuration function. | |
26 | # | |
27 | ## This function does the main work. It is responsible for calling the subfunction | |
28 | ## to read the given config file (or use the default one if none has been specified), | |
29 | ## and push the returned object to the validate subfunction. Finally the validated | |
30 | ## settings will be merged with the default ones (existing defaults will be overwritten). | |
31 | # | |
32 | sub UseConfig ($) { | |
33 | my $file = $_[0]; | |
34 | ||
35 | # If not file has been specified, use the default one. | |
36 | unless ($file) { | |
37 | $file = $configfile; | |
38 | } | |
39 | ||
40 | # Call subfunction to get the settings from config file. | |
41 | # Store the options and values in a temporary hash. | |
42 | my %temp = &ReadConfig($file); | |
43 | ||
44 | # Validate config settings. | |
45 | my $error = &CheckConfig(\%temp); | |
46 | ||
47 | # As long, as no error message is returned, the config is valid. | |
48 | unless ($error) { | |
49 | # Merge hash with contains the default | |
50 | # and temporary config hash. If both hashes contains | |
51 | # the same keys, the keys+values of the first one (%defaults) | |
52 | # will be overwritten. | |
53 | my %config = (%defaults, %temp); | |
54 | ||
55 | # Return the final configuration hash. | |
56 | return %config; | |
57 | ||
58 | # If an error message is returned, exit and print the error message. | |
59 | } else { | |
c0a59a63 | 60 | die "Invalid configuration: $error"; |
2aed491c SS |
61 | } |
62 | } | |
63 | ||
64 | # | |
65 | ## ReadConfig (configfile) function. | |
66 | # | |
67 | ## This function is used to read a given configuration file and store the | |
68 | ## values into a hash which will be returned. | |
69 | # | |
70 | sub ReadConfig ($) { | |
71 | my $file = $_[0]; | |
72 | ||
73 | # Hash to store the read-in configuration options and values. | |
74 | my %config = (); | |
75 | ||
76 | # Check if the configfile exists and is read-able. | |
77 | unless (-r "$file") { | |
c0a59a63 | 78 | die "The given configfile ($file) does not exist, or is not read-able: $!"; |
2aed491c SS |
79 | } |
80 | ||
81 | # Open the config file and read-in all configuration options and values. | |
c0a59a63 | 82 | open(CONF, "$file") or die "Could not open $file: $!"; |
2aed491c SS |
83 | |
84 | # Process line by line. | |
85 | while (my $line = <CONF>) { | |
86 | # Skip comments. | |
87 | next if ($line =~ /\#/); | |
88 | ||
89 | # Skip blank lines. | |
90 | next if ($line =~ /^\s*$/); | |
91 | ||
92 | # Remove any newlines. | |
93 | chomp($line); | |
94 | ||
2aed491c SS |
95 | # Check line lenght, skip it, if it is longer than, the |
96 | # allowed maximum. | |
97 | my $length = length("$line"); | |
98 | next if ($length gt $maxlength); | |
99 | ||
27d58348 SS |
100 | # Remove any whitespaces. |
101 | $line=~ s/ //g; | |
102 | ||
2aed491c SS |
103 | # Splitt line into two parts. |
104 | my ($option, $value) = split (/=/, $line); | |
105 | ||
106 | # Add config option and value to the config hash. | |
107 | $config{$option} = $value; | |
108 | } | |
109 | ||
110 | # Close the config file. | |
111 | close(CONF); | |
112 | ||
113 | # Return the configuration hash. | |
114 | return %config; | |
115 | } | |
116 | ||
117 | # | |
118 | ## The CheckConfig function. | |
119 | # | |
120 | ## This function is responsible to validate configure options which has | |
121 | ## to be passed as a hash. It will return an error message which provides some | |
122 | ## deeper details, if any problems have been detected. | |
123 | # | |
124 | sub CheckConfig (\%) { | |
125 | # Dereference the given hash-ref and store | |
126 | # them into a new temporary hash. | |
127 | my %config = %{ $_[0] }; | |
128 | ||
129 | # If a BlockTime has been configured, check if the value is a natural number. | |
130 | if (exists($config{BlockTime})) { | |
131 | # Get the configured value for "BlockTime". | |
132 | my $value = $config{BlockTime}; | |
133 | ||
134 | # Call subroutine for validation. | |
135 | my $error = &check_number("$value"); | |
136 | ||
137 | # If the check fails, immediately return an error message. | |
138 | if ($error) { | |
139 | return "Invalid BlockTime: $error"; | |
140 | } | |
141 | } | |
142 | ||
143 | # If a BlockCount has been configured, check if the value is a natural number. | |
144 | if (exists($config{BlockCount})) { | |
145 | # Get the configured value for "BlockCount". | |
146 | my $value = $config{BlockCount}; | |
147 | ||
148 | # Call subroutine for validation. | |
149 | my $error = &check_number("$value"); | |
150 | ||
151 | # If the check fails, immediately return an error message. | |
152 | if ($error) { | |
153 | return "Invalid BlockCount: $error"; | |
154 | } | |
155 | } | |
156 | ||
43ab646a SS |
157 | # Gather details about supported log levels. |
158 | my %supported_loglevels = &Guardian::Logger::GetLogLevels(); | |
159 | ||
160 | # Check if the configured log level is valid. | |
161 | unless (exists ($supported_loglevels{$config{LogLevel}})) { | |
162 | return "Invalid LogLevel: $config{LogLevel}"; | |
163 | } | |
2aed491c SS |
164 | |
165 | # The config looks good, so return nothing (no error message). | |
166 | return undef | |
167 | } | |
168 | ||
169 | # | |
170 | ## The check_number subroutine. | |
171 | # | |
172 | ## This simple subroutine is used to check if a given string is numeric | |
173 | ## and contains a natural number which has to be greater than zero. | |
174 | # | |
175 | sub check_number ($) { | |
176 | my $input = $_[0]; | |
177 | ||
178 | # Check if the input is a natural number. | |
179 | unless ($input =~ /^\d+$/) { | |
180 | return "$input is not a natural number"; | |
181 | } | |
182 | ||
183 | # Check if the number is greater than zero. | |
184 | unless ($input gt "0") { | |
185 | return "$input has to be greater than zero"; | |
186 | } | |
187 | ||
188 | # Input is okay, return no error message (nothing). | |
189 | return undef; | |
190 | } | |
191 | ||
192 | 1; |