mirror of
https://github.com/libevent/libevent.git
synced 2025-01-31 09:12:55 +08:00
improved nroff mdoc for the man page
svn:r241
This commit is contained in:
Niels Provos
parent
152f570047
commit
ea52d9fd8d
209
evdns.3
209
evdns.3
@ -105,17 +105,19 @@ numbers should be unpredictable for spoofing reasons. There are
|
||||
three methods for generating them here and you must define exactly
|
||||
one of them. In increasing order of preference:
|
||||
.Pp
|
||||
DNS_USE_GETTIMEOFDAY_FOR_ID:
|
||||
Using the bottom 16 bits of the usec result from gettimeofday. This
|
||||
is a pretty poor solution but should work anywhere.
|
||||
DNS_USE_CPU_CLOCK_FOR_ID:
|
||||
Using the bottom 16 bits of the nsec result from the CPU's time
|
||||
counter. This is better, but may not work everywhere. Requires
|
||||
POSIX realtime support and you'll need to link against -lrt on
|
||||
glibc systems at least.
|
||||
DNS_USE_OPENSSL_FOR_ID:
|
||||
Uses the OpenSSL RAND_bytes call to generate the data. You must
|
||||
have seeded the pool before making any calls to this library.
|
||||
.Bl -tag -width "DNS_USE_GETTIMEOFDAY_FOR_ID" -compact -offset indent
|
||||
.It DNS_USE_GETTIMEOFDAY_FOR_ID
|
||||
Using the bottom 16 bits of the usec result from gettimeofday. This
|
||||
is a pretty poor solution but should work anywhere.
|
||||
.It DNS_USE_CPU_CLOCK_FOR_ID
|
||||
Using the bottom 16 bits of the nsec result from the CPU's time
|
||||
counter. This is better, but may not work everywhere. Requires
|
||||
POSIX realtime support and you'll need to link against -lrt on
|
||||
glibc systems at least.
|
||||
.It DNS_USE_OPENSSL_FOR_ID
|
||||
Uses the OpenSSL RAND_bytes call to generate the data. You must
|
||||
have seeded the pool before making any calls to this library.
|
||||
.El
|
||||
.Pp
|
||||
The library keeps track of the state of nameservers and will avoid
|
||||
them when they go down. Otherwise it will round robin between them.
|
||||
@ -148,13 +150,29 @@ evdns_resolve. Searching can also drastically slow down the resolution
|
||||
of names.
|
||||
.Pp
|
||||
To disable searching:
|
||||
1. Never set it up. If you never call evdns_resolv_conf_parse or
|
||||
evdns_search_add then no searching will occur.
|
||||
.Pp
|
||||
2. If you do call evdns_resolv_conf_parse then don't pass
|
||||
DNS_OPTION_SEARCH (or DNS_OPTIONS_ALL, which implies it).
|
||||
.Pp
|
||||
3. When calling evdns_resolve, pass the DNS_QUERY_NO_SEARCH flag.
|
||||
.Bl -enum -compact -offset indent
|
||||
.It
|
||||
Never set it up. If you never call
|
||||
.Fn evdns_resolv_conf_parse,
|
||||
.Fn evdns_init,
|
||||
or
|
||||
.Fn evdns_search_add
|
||||
then no searching will occur.
|
||||
.It
|
||||
If you do call
|
||||
.Fn evdns_resolv_conf_parse
|
||||
then don't pass
|
||||
.Va DNS_OPTION_SEARCH
|
||||
(or
|
||||
.Va DNS_OPTIONS_ALL,
|
||||
which implies it).
|
||||
.It
|
||||
When calling
|
||||
.Fn evdns_resolve,
|
||||
pass the
|
||||
.Va DNS_QUERY_NO_SEARCH
|
||||
flag.
|
||||
.El
|
||||
.Pp
|
||||
The order of searches depends on the number of dots in the name. If the
|
||||
number is greater than the ndots setting then the names is first tried
|
||||
@ -171,86 +189,95 @@ For example, with ndots set to 1 (the default) and a search domain list of
|
||||
Query: www.abc
|
||||
Order: www.abc., www.abc.myhome.net
|
||||
.Pp
|
||||
API reference:
|
||||
.Sh API reference
|
||||
.Pp
|
||||
int evdns_nameserver_add(unsigned long int address)
|
||||
Add a nameserver. The address should be an IP address in
|
||||
network byte order. The type of address is chosen so that
|
||||
it matches in_addr.s_addr.
|
||||
Returns non-zero on error.
|
||||
.Bl -tag -width 0123456
|
||||
.It Ft int Fn evdns_init
|
||||
Initializes support for non-blocking name resolution by calling
|
||||
.Fn evdns_resolv_conf_parse
|
||||
on UNIX and
|
||||
.Fn evdns_config_windows_nameservers
|
||||
on Windows.
|
||||
.It Ft int Fn evdns_nameserver_add "unsigned long int address"
|
||||
Add a nameserver. The address should be an IP address in
|
||||
network byte order. The type of address is chosen so that
|
||||
it matches in_addr.s_addr.
|
||||
Returns non-zero on error.
|
||||
.It Ft int Fn evdns_nameserver_ip_add "const char *ip_as_string"
|
||||
This wraps the above function by parsing a string as an IP
|
||||
address and adds it as a nameserver.
|
||||
Returns non-zero on error
|
||||
.It Ft int Fn evdns_resolve "const char *name" "int flags" "evdns_callback_type callback" "void *ptr"
|
||||
Resolve a name. The name parameter should be a DNS name.
|
||||
The flags parameter should be 0, or DNS_QUERY_NO_SEARCH
|
||||
which disables searching for this query. (see defn of
|
||||
searching above).
|
||||
.Pp
|
||||
int evdns_nameserver_ip_add(const char *ip_as_string)
|
||||
This wraps the above function by parsing a string as an IP
|
||||
address and adds it as a nameserver.
|
||||
Returns non-zero on error
|
||||
The callback argument is a function which is called when
|
||||
this query completes and ptr is an argument which is passed
|
||||
to that callback function.
|
||||
.Pp
|
||||
int evdns_resolve(const char *name, int flags,
|
||||
evdns_callback_type callback,
|
||||
void *ptr)
|
||||
Resolve a name. The name parameter should be a DNS name.
|
||||
The flags parameter should be 0, or DNS_QUERY_NO_SEARCH
|
||||
which disables searching for this query. (see defn of
|
||||
searching above).
|
||||
Returns non-zero on error
|
||||
.It Ft void Fn evdns_search_clear
|
||||
Clears the list of search domains
|
||||
.It Ft void Fn evdns_search_add "const char *domain"
|
||||
Add a domain to the list of search domains
|
||||
.It Ft void Fn evdns_search_ndots_set "int ndots"
|
||||
Set the number of dots which, when found in a name, causes
|
||||
the first query to be without any search domain.
|
||||
.It Ft int Fn evdns_count_nameservers "void"
|
||||
Return the number of configured nameservers (not necessarily the
|
||||
number of running nameservers). This is useful for double-checking
|
||||
whether our calls to the various nameserver configuration functions
|
||||
have been successful.
|
||||
.It Ft int Fn evdns_clear_nameservers_and_suspend "void"
|
||||
Remove all currently configured nameservers, and suspend all pending
|
||||
resolves. Resolves will not necessarily be re-attempted until
|
||||
evdns_resume() is called.
|
||||
.It Ft int Fn evdns_resume "void"
|
||||
Re-attempt resolves left in limbo after an earlier call to
|
||||
evdns_clear_nameservers_and_suspend().
|
||||
.It Ft int Fn evdns_config_windows_nameservers "void"
|
||||
Attempt to configure a set of nameservers based on platform settings on
|
||||
a win32 host. Preferentially tries to use GetNetworkParams; if that fails,
|
||||
looks in the registry. Returns 0 on success, nonzero on failure.
|
||||
.It Ft int Fn evdns_resolv_conf_parse "int flags" "const char *filename"
|
||||
Parse a resolv.conf like file from the given filename.
|
||||
.Pp
|
||||
The callback argument is a function which is called when
|
||||
this query completes and ptr is an argument which is passed
|
||||
to that callback function.
|
||||
See the man page for resolv.conf for the format of this file.
|
||||
The flags argument determines what information is parsed from
|
||||
this file:
|
||||
.Bl -tag -width "DNS_OPTION_NAMESERVERS" -offset indent -compact -nested
|
||||
.It DNS_OPTION_SEARCH
|
||||
domain, search and ndots options
|
||||
.It DNS_OPTION_NAMESERVERS
|
||||
nameserver lines
|
||||
.It DNS_OPTION_MISC
|
||||
timeout and attempts options
|
||||
.It DNS_OPTIONS_ALL
|
||||
all of the above
|
||||
.El
|
||||
.Pp
|
||||
Returns non-zero on error
|
||||
.Pp
|
||||
void evdns_search_clear()
|
||||
Clears the list of search domains
|
||||
.Pp
|
||||
void evdns_search_add(const char *domain)
|
||||
Add a domain to the list of search domains
|
||||
.Pp
|
||||
void evdns_search_ndots_set(int ndots)
|
||||
Set the number of dots which, when found in a name, causes
|
||||
the first query to be without any search domain.
|
||||
.Pp
|
||||
int evdns_count_nameservers(void)
|
||||
Return the number of configured nameservers (not necessarily the
|
||||
number of running nameservers). This is useful for double-checking
|
||||
whether our calls to the various nameserver configuration functions
|
||||
have been successful.
|
||||
.Pp
|
||||
int evdns_clear_nameservers_and_suspend(void)
|
||||
Remove all currently configured nameservers, and suspend all pending
|
||||
resolves. Resolves will not necessarily be re-attempted until
|
||||
evdns_resume() is called.
|
||||
.Pp
|
||||
int evdns_resume(void)
|
||||
Re-attempt resolves left in limbo after an earlier call to
|
||||
evdns_clear_nameservers_and_suspend().
|
||||
.Pp
|
||||
int evdns_config_windows_nameservers(void)
|
||||
Attempt to configure a set of nameservers based on platform settings on
|
||||
a win32 host. Preferentially tries to use GetNetworkParams; if that fails,
|
||||
looks in the registry. Returns 0 on success, nonzero on failure.
|
||||
.Pp
|
||||
int evdns_resolv_conf_parse(int flags, const char *filename)
|
||||
Parse a resolv.conf like file from the given filename.
|
||||
.Pp
|
||||
See the man page for resolv.conf for the format of this file.
|
||||
The flags argument determines what information is parsed from
|
||||
this file:
|
||||
DNS_OPTION_SEARCH - domain, search and ndots options
|
||||
DNS_OPTION_NAMESERVERS - nameserver lines
|
||||
DNS_OPTION_MISC - timeout and attempts options
|
||||
DNS_OPTIONS_ALL - all of the above
|
||||
The following directives are not parsed from the file:
|
||||
The following directives are not parsed from the file:
|
||||
sortlist, rotate, no-check-names, inet6, debug
|
||||
.Pp
|
||||
Returns non-zero on error:
|
||||
0 no errors
|
||||
1 failed to open file
|
||||
2 failed to stat file
|
||||
3 file too large
|
||||
4 out of memory
|
||||
5 short read from file
|
||||
.Pp
|
||||
Internals:
|
||||
.Pp
|
||||
Returns non-zero on error:
|
||||
.Bl -tag -width "0" -offset indent -compact -nested
|
||||
.It 0
|
||||
no errors
|
||||
.It 1
|
||||
failed to open file
|
||||
.It 2
|
||||
failed to stat file
|
||||
.It 3
|
||||
file too large
|
||||
.It 4
|
||||
out of memory
|
||||
.It 5
|
||||
short read from file
|
||||
.El
|
||||
.El
|
||||
.Sh Internals:
|
||||
Requests are kept in two queues. The first is the inflight queue. In
|
||||
this queue requests have an allocated transaction id and nameserver.
|
||||
They will soon be transmitted if they haven't already been.
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user