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Diffstat (limited to 'doc/libs6dns/hosts.html')
| -rw-r--r-- | doc/libs6dns/hosts.html | 159 |
1 files changed, 136 insertions, 23 deletions
diff --git a/doc/libs6dns/hosts.html b/doc/libs6dns/hosts.html index 93bfc10..b9a03bf 100644 --- a/doc/libs6dns/hosts.html +++ b/doc/libs6dns/hosts.html @@ -71,7 +71,7 @@ use the macros without a <tt>_r</tt> suffix. <h2> Functions </h2> -<h3> Preparation </h3> +<h3> Compilation </h3> <p> <code> int s6dns_hosts_compile (int fdr, int fdw) </code> <br /> @@ -84,45 +84,158 @@ on failure. </p> <p> - You normally don't need to use this function yourself, because -it's implicitly used by the following one. + You normally don't need to use this function yourself. To +compile the hosts database prior to use, you can call the +<a href="../s6-dns-hosts-compile.html">s6-dns-hosts-compile</a> +program (which uses this function). Alternatively, +at initialization time, the hosts database will be compiled +automatically if there isn't a more recent compiled version. </p> +<h3> Initialization </h3> + <p> -<code> int s6dns_hosts_init (void) </code> <br /> -Initializes the database from the <tt>/etc/hosts</tt> file. -If there's a pre-compiled <tt>/etc/hosts.cdb</tt> file that +<code> int s6dns_hosts_init (cdb *c, char const *txtfile, char const *cdbfile, char const *prefix) </code> <br /> +Initializes the compiled hosts database in <em>*c</em>. +If there's a pre-compiled <em>cdbfile</em> file that is more recent than <tt>/etc/hosts</tt>, then it is used; -else, the <tt>/etc/hosts</tt> file is compiled into a -temporary file under <tt>/tmp</tt>, which is used and -immediately unlinked. The function returns 1 on success and -0 (and sets errno) on failure. +else, the <em>txtfile</em> file is compiled into a +temporary file starting with <em>prefix</em>, which is used and +immediately unlinked. The function returns -1 (and sets errno) +on failure, 1 on success, and 0 if it can find neither a +suitable <em>cdbfile</em> nor a suitable <em>txtfile</em>. </p> <p> -<code> int s6dns_hosts_init_r (cdb *c, char const *txtfile, char const *cdbfile, char const *prefix) </code> <br /> -The generic version of the above function. Initializes the database -in <em>*c</em> from the compiled file <em>cdbfile</em> if it exists and is -more recent than <em>txtfile</em>, else compiles <em>txtfile</em> into -a temporary file with a path starting with <em>prefix</em>, makes it -accessible in <em>*c</em> and immediately unlinks it. +<code> void s6dns_hosts_free (cdb *c) </code> <br /> +Frees the compiled hosts database in <em>c</em>. </p> <p> -<code> void s6dns_hosts_free (void) </code> <br /> -Frees the compiled hosts database. Only use this if -you're certain you'll have no more use for it. + You probably don't need to use these functions yourself: +instead, the higher-level <tt>s6dns_init()</tt> and +<tt>s6dns_finish()</tt> functions perform all the necessary +initialization and cleanup, including the hosts database one. </p> + +<h3> IP to name resolution </h3> + <p> -<code> void s6dns_hosts_free_r (cdb *c) </code> <br /> -The generic version of the above function. +<code> int s6dns_hosts_name (char const *ip, stralloc *storage, genalloc *indices, int is6) </code> <br /> +Gets the list of names for IP address <em>ip</em> from the hosts database. +The names are stored in the stralloc <em>*storage</em>; for each name, +its index in <em>storage→s</em> is appended, as a <tt>size_t</tt>, +to the genalloc <em>*indices</em>. If <em>is6</em> is nonzero, <em>ip</em> +is interpreted as an IPv6 address, i.e. a network byte order sequence of +16 bytes; otherwise it is interpreted as an IPv4 address, i.e. a network +byte order sequence of 4 bytes. The function returns -1 (and sets errno) +in case of failure, 0 if no match could be found (which includes no +existing hosts database), or the number of names it found. Names listed +as the first name on a line in <tt>/etc/hosts</tt> are always given as +fully qualified, i.e. with a terminating dot; other names are given as +they were input in <tt>/etc/hosts</tt>. </p> -<h3> IP to name resolution </h3> +<p> +<code> int s6dns_hosts_name4 (char const *ip, stralloc *storage, genalloc *indices) </code> <br /> +Same, but <em>ip</em> is assumed to be an IPv4. +</p> + +<p> +<code> int s6dns_hosts_name6 (char const *ip, stralloc *storage, genalloc *indices) </code> <br /> +Same, but <em>ip</em> is assumed to be an IPv6. +</p> + +<h3> Name to IP resolution </h3> + +<h4> Fully qualified names </h4> + +<p> +<code> extern int s6dns_hosts_a_noq (char const *name, stralloc *ip4s) </code> <br /> +Gets the list of IPv4 addresses for name <em>name</em> from the hosts database. +The addresses are stored in the stralloc <em>*ip4s</em>, in network byte order, +4 bytes per item. <em>name</em> is assumed to be fully qualified: <tt>skarnet.org</tt> +will yield the same results as <tt>skarnet.org.</tt>, and <tt>blah</tt> will yield +the same results as <tt>blah.</tt> with the ending dot. The function returns -1 +(and sets errno) in case of failure, 0 if no match (including no valid hosts +database), or the number of IP addresses appended to <em>*ip4s</em> (i.e. the +length increase divided by 4). +</p> + +<p> +<code> extern int s6dns_hosts_aaaa_noq (char const *name, stralloc *ip6s) </code> <br /> +Same as above, but gets the list of IPv6 addresses for <em>name</em>; there are +16 bytes per address instead of 4. +</p> + +<p> +<code> extern int s6dns_hosts_aaaaa_noq (char const *name, genalloc *ips) </code> <br /> +Same as above, but gets the list of all IP addresses for <em>name</em>, v4 or v6 +indiscriminately. Every address is stored in the genalloc <em>*ips</em> as an +<a href="https://git.skarnet.org/cgi-bin/cgit.cgi/skalibs/tree/src/headers/ip46-header#n21"><tt>ip46full</tt> structure</a>. +</p> + +<h4> Aliases </h4> + +<p> +<code> extern int s6dns_hosts_a_unq (char const *name, stralloc *ip4s) </code> <br /> +Gets the list of IPv4 addresses for name <em>name</em> from the hosts database. +The addresses are stored in the stralloc <em>*ip4s</em>, in network byte order, +4 bytes per item. <em>name</em> is assumed to be unqualified: <tt>blah</tt> +is interpreted as a local alias that will only match a <tt>blah</tt> +entry in <tt>/etc/hosts</tt> that does <strong>not</strong> appear as a first +entry. The function returns -1 +(and sets errno) in case of failure, 0 if no match (including no valid hosts +database), or the number of IP addresses appended to <em>*ip4s</em> (i.e. the +length increase divided by 4). +</p> + +<p> +<code> extern int s6dns_hosts_aaaa_unq (char const *name, stralloc *ip6s) </code> <br /> +Same as above, but gets the list of IPv6 addresses for <em>name</em>; there are +16 bytes per address instead of 4. +</p> + +<p> +<code> extern int s6dns_hosts_aaaaa_unq (char const *name, genalloc *ips) </code> <br /> +Same as above, but gets the list of all IP addresses for <em>name</em>, v4 or v6 +indiscriminately. Every address is stored in the genalloc <em>*ips</em> as an +<a href="https://git.skarnet.org/cgi-bin/cgit.cgi/skalibs/tree/src/headers/ip46-header#n21"><tt>ip46full</tt> structure</a>. +</p> + +<h4> With qualification </h4> + +<p> +<code> extern int s6dns_hosts_a_q (char const *name, stralloc *ip4s) </code> <br /> +Gets the list of IPv4 addresses, from the hosts database, for all possible +qualifications for name <em>name</em>. +The addresses are stored in the stralloc <em>*ip4s</em>, in network byte order, +4 bytes per item. The function returns -1 +(and sets errno) in case of failure, 0 if no match (including no valid hosts +database), or the number of IP addresses appended to <em>*ip4s</em> (i.e. the +length increase divided by 4). +</p> + +<p> + First, <em>name</em> is looked up in the hosts database as a simple +unqualified names. Then, <em>name</em> is qualified with all the suffixes +read from <tt>/etc/resolv.conf</tt>, and all of the resulting FQDNs are +looked up in the hosts database. All the results are concatenated and +appended to the <em>*ip4s</em> stralloc. +</p> + +<p> +<code> extern int s6dns_hosts_aaaa_q (char const *name, stralloc *ip6s) </code> <br /> +Same as above, but gets the list of IPv6 addresses for <em>name</em>; there are +16 bytes per address instead of 4. +</p> <p> -<code> int s6dns_hosts_name_r (cdb const *c, char const *ip, stralloc *storage, genalloc *indices, int is6) </code> <br /> +<code> extern int s6dns_hosts_aaaaa_q (char const *name, genalloc *ips) </code> <br /> +Same as above, but gets the list of all IP addresses for <em>name</em>, v4 or v6 +indiscriminately. Every address is stored in the genalloc <em>*ips</em> as an +<a href="https://git.skarnet.org/cgi-bin/cgit.cgi/skalibs/tree/src/headers/ip46-header#n21"><tt>ip46full</tt> structure</a>. </p> </body> |