Wed Aug 18 22:33:40 2010

Asterisk developer's documentation


acl.h

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2006, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  * \brief Access Control of various sorts
00021  */
00022 
00023 #ifndef _ASTERISK_ACL_H
00024 #define _ASTERISK_ACL_H
00025 
00026 
00027 #if defined(__cplusplus) || defined(c_plusplus)
00028 extern "C" {
00029 #endif
00030 
00031 #include "asterisk/network.h"
00032 #include "asterisk/io.h"
00033 
00034 #define AST_SENSE_DENY                  0
00035 #define AST_SENSE_ALLOW                 1
00036 
00037 /* Host based access control */
00038 
00039 /*! \brief internal representation of acl entries
00040  * In principle user applications would have no need for this,
00041  * but there is sometimes a need to extract individual items,
00042  * e.g. to print them, and rather than defining iterators to
00043  * navigate the list, and an externally visible 'struct ast_ha_entry',
00044  * at least in the short term it is more convenient to make the whole
00045  * thing public and let users play with them.
00046  */
00047 struct ast_ha {
00048         /* Host access rule */
00049         struct in_addr netaddr;  
00050         struct in_addr netmask;
00051         int sense;
00052         struct ast_ha *next;
00053 };
00054 
00055 /*!
00056  * \brief Free a list of HAs
00057  *
00058  * \details
00059  * Given the head of a list of HAs, it and all appended
00060  * HAs are freed
00061  *
00062  * \param ha The head of the list of HAs to free
00063  * \retval void
00064  */
00065 void ast_free_ha(struct ast_ha *ha);
00066 
00067 /*!
00068  * \brief Copy the contents of one HA to another
00069  *
00070  * \details
00071  * This copies the internals of the 'from' HA to the 'to'
00072  * HA. It is important that the 'to' HA has been allocated
00073  * prior to calling this function
00074  *
00075  * \param from Source HA to copy
00076  * \param to Destination HA to copy to
00077  * \retval void
00078  */
00079 void ast_copy_ha(const struct ast_ha *from, struct ast_ha *to);
00080 
00081 /*!
00082  * \brief Add a new rule to a list of HAs
00083  *
00084  * \details
00085  * This adds the new host access rule to the end of the list
00086  * whose head is specified by the path parameter. Rules are
00087  * evaluated in a way such that if multiple rules apply to
00088  * a single IP address/subnet mask, then the rule latest
00089  * in the list will be used.
00090  *
00091  * \param sense Either "permit" or "deny" (Actually any 'p' word will result
00092  * in permission, and any other word will result in denial)
00093  * \param stuff The IP address and subnet mask, separated with a '/'. The subnet
00094  * mask can either be in dotted-decimal format or in CIDR notation (i.e. 0-32).
00095  * \param path The head of the HA list to which we wish to append our new rule. If
00096  * NULL is passed, then the new rule will become the head of the list
00097  * \param[out] error The integer error points to will be set non-zero if an error occurs
00098  * \return The head of the HA list
00099  */
00100 struct ast_ha *ast_append_ha(const char *sense, const char *stuff, struct ast_ha *path, int *error);
00101 
00102 /*!
00103  * \brief Apply a set of rules to a given IP address
00104  *
00105  * \details
00106  * The list of host access rules is traversed, beginning with the
00107  * input rule. If the IP address given matches a rule, the "sense"
00108  * of that rule is used as the return value. Note that if an IP
00109  * address matches multiple rules that the last one matched will be
00110  * the one whose sense will be returned.
00111  *
00112  * \param ha The head of the list of host access rules to follow
00113  * \param sin A sockaddr_in whose address is considered when matching rules
00114  * \retval AST_SENSE_ALLOW The IP address passes our ACL
00115  * \retval AST_SENSE_DENY The IP address fails our ACL
00116  */
00117 int ast_apply_ha(struct ast_ha *ha, struct sockaddr_in *sin);
00118 
00119 /*!
00120  * \brief Get the IP address given a hostname
00121  *
00122  * \details
00123  * Similar in nature to ast_gethostbyname, except that instead
00124  * of getting an entire hostent structure, you instead are given
00125  * only the IP address inserted into a sockaddr_in structure.
00126  *
00127  * \param[out] sin The IP address is written into sin->sin_addr
00128  * \param value The hostname to look up
00129  * \retval 0 Success
00130  * \retval -1 Failure
00131  */
00132 int ast_get_ip(struct sockaddr_in *sin, const char *value);
00133 
00134 /*!
00135  * \brief Get the IP address given a hostname and optional service
00136  *
00137  * \details
00138  * If the service parameter is non-NULL, then an SRV lookup will be made by
00139  * prepending the service to the value parameter, separated by a '.'
00140  * For example, if value is "example.com" and service is "_sip._udp" then
00141  * an SRV lookup will be done for "_sip._udp.example.com". If service is NULL,
00142  * then this function acts exactly like a call to ast_get_ip.
00143  *
00144  * \param[out] sin The IP address is written into sin->sin_addr
00145  * \param value The hostname to look up
00146  * \param service A specific service provided by the host. A NULL service results
00147  * in an A-record lookup instead of an SRV lookup
00148  * \retval 0 Success
00149  * \retval -1 Failure
00150  */
00151 int ast_get_ip_or_srv(struct sockaddr_in *sin, const char *value, const char *service);
00152 
00153 /*!
00154  * \brief Get our local IP address when contacting a remote host
00155  *
00156  * \details
00157  * This function will attempt to connect(2) to them over UDP using a source
00158  * port of 5060. If the connect(2) call is successful, then we inspect the
00159  * sockaddr_in output parameter of connect(2) to determine the IP address
00160  * used to connect to them. This IP address is then copied into us.
00161  *
00162  * \param them The IP address to which we wish to attempt to connect
00163  * \param[out] us The source IP address used to connect to them
00164  * \retval -1 Failure
00165  * \retval 0 Success
00166  */
00167 int ast_ouraddrfor(struct in_addr *them, struct in_addr *us);
00168 
00169 /*!
00170  * \brief Find an IP address associated with a specific interface
00171  *
00172  * \details
00173  * Given an interface such as "eth0" we find the primary IP address
00174  * associated with it using the SIOCGIFADDR ioctl. If the ioctl call
00175  * should fail, we populate address with 0s.
00176  *
00177  * \note
00178  * This function is not actually used anywhere
00179  *
00180  * \param iface The interface name whose IP address we wish to find
00181  * \param[out] address The interface's IP address is placed into this param
00182  * \retval -1 Failure. address is filled with 0s
00183  * \retval 0 Success
00184  */
00185 int ast_lookup_iface(char *iface, struct in_addr *address);
00186 
00187 /*!
00188  * \brief Duplicate the contents of a list of host access rules
00189  *
00190  * \details
00191  * A deep copy of all ast_has in the list is made. The returned
00192  * value is allocated on the heap and must be freed independently
00193  * of the input parameter when finished.
00194  *
00195  * \note
00196  * This function is not actually used anywhere.
00197  *
00198  * \param original The ast_ha to copy
00199  * \retval The head of the list of duplicated ast_has
00200  */
00201 struct ast_ha *ast_duplicate_ha_list(struct ast_ha *original);
00202 
00203 /*!
00204  * \brief Find our IP address
00205  *
00206  * \details
00207  * This function goes through many iterations in an attempt to find
00208  * our IP address. If any step along the way should fail, we move to the
00209  * next item in the list. Here are the steps taken:
00210  * - If bindaddr has a non-zero IP address, that is copied into ourip
00211  * - We use a combination of gethostname and ast_gethostbyname to find our
00212  *   IP address.
00213  * - We use ast_ouraddrfor with 198.41.0.4 as the destination IP address
00214  * - We try some platform-specific socket operations to find the IP address
00215  *
00216  * \param[out] ourip Our IP address is written here when it is found
00217  * \param bindaddr A hint used for finding our IP. See the steps above for
00218  * more details
00219  * \retval 0 Success
00220  * \retval -1 Failure
00221  */
00222 int ast_find_ourip(struct in_addr *ourip, struct sockaddr_in bindaddr);
00223 
00224 /*!
00225  * \brief Convert a string to the appropriate COS value
00226  *
00227  * \param value The COS string to convert
00228  * \param[out] cos The integer representation of that COS value
00229  * \retval -1 Failure
00230  * \retval 0 Success
00231  */
00232 int ast_str2cos(const char *value, unsigned int *cos);
00233 
00234 /*!
00235  * \brief Convert a string to the appropriate TOS value
00236  *
00237  * \param value The TOS string to convert
00238  * \param[out] tos The integer representation of that TOS value
00239  * \retval -1 Failure
00240  * \retval 0 Success
00241  */
00242 int ast_str2tos(const char *value, unsigned int *tos);
00243 
00244 /*!
00245  * \brief Convert a TOS value into its string representation
00246  *
00247  * \param tos The TOS value to look up
00248  * \return The string equivalent of the TOS value
00249  */
00250 const char *ast_tos2str(unsigned int tos);
00251 
00252 #if defined(__cplusplus) || defined(c_plusplus)
00253 }
00254 #endif
00255 
00256 #endif /* _ASTERISK_ACL_H */

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