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Diffstat (limited to 'ares_init.3')
| -rw-r--r-- | ares_init.3 | 170 |
1 files changed, 14 insertions, 156 deletions
diff --git a/ares_init.3 b/ares_init.3 index fb25306..0baf4b7 100644 --- a/ares_init.3 +++ b/ares_init.3 @@ -16,167 +16,24 @@ .\" .TH ARES_INIT 3 "5 March 2010" .SH NAME -ares_init, ares_init_options \- Initialize a resolver channel +ares_init \- Initialize a resolver channel .SH SYNOPSIS .nf -.B #include <ares.h> -.PP -.B int ares_init(ares_channel *\fIchannelptr\fP) -.B int ares_init_options(ares_channel *\fIchannelptr\fP, -.B struct ares_options *\fIoptions\fP, int \fIoptmask\fP) -.PP -.B cc file.c -lcares +#include <ares.h> + +int ares_init(ares_channel *\fIchannelptr\fP) .fi .SH DESCRIPTION -The \fBares_init\fP function initializes a communications channel for name -service lookups. If it returns successfully, \fBares_init\fP will set the +The \fBares_init(3)\fP function initializes a communications channel for name +service lookups. If it returns successfully, \fBares_init(3)\fP will set the variable pointed to by \fIchannelptr\fP to a handle used to identify the name -service channel. The caller should invoke -.BR ares_destroy (3) -on the handle when the channel is no longer needed. -.PP -The \fBares_init_options\fP function also initializes a name service channel, -with additional options useful for applications requiring more control over -name service configuration. The \fIoptmask\fP parameter specifies which fields -in the structure pointed to by \fIoptions\fP are set, as follows: -.TP 18 -.B ARES_OPT_FLAGS -.B int \fIflags\fP; -.br -Flags controlling the behavior of the resolver. See below for a -description of possible flag values. -.TP 18 -.B ARES_OPT_TIMEOUT -.B int \fItimeout\fP; -.br -The number of seconds each name server is given to respond to a query on the -first try. (After the first try, the timeout algorithm becomes more -complicated, but scales linearly with the value of \fItimeout\fP.) The -default is five seconds. This option is being deprecated by -\fIARES_OPT_TIMEOUTMS\fP starting in c-ares 1.5.2. -.TP 18 -.B ARES_OPT_TIMEOUTMS -.B int \fItimeout\fP; -.br -The number of milliseconds each name server is given to respond to a query on -the first try. (After the first try, the timeout algorithm becomes more -complicated, but scales linearly with the value of \fItimeout\fP.) The -default is five seconds. Note that this option is specified with the same -struct field as the former \fIARES_OPT_TIMEOUT\fP, it is but the option bits -that tell c-ares how to interpret the number. This option was added in c-ares -1.5.2. -.TP 18 -.B ARES_OPT_TRIES -.B int \fItries\fP; -.br -The number of tries the resolver will try contacting each name server -before giving up. The default is four tries. -.TP 18 -.B ARES_OPT_NDOTS -.B int \fIndots\fP; -.br -The number of dots which must be present in a domain name for it to be -queried for "as is" prior to querying for it with the default domain -extensions appended. The default value is 1 unless set otherwise by -resolv.conf or the RES_OPTIONS environment variable. -.TP 18 -.B ARES_OPT_PORT -.B unsigned short \fIport\fP; -.br -The port to use for queries (both TCP and UDP), in network byte order. -The default value is 53 (in network byte order), the standard name -service port. -.TP 18 -.B ARES_OPT_SERVERS -.B struct in_addr *\fIservers\fP; -.br -.B int \fInservers\fP; -.br -The list of IPv4 servers to contact, instead of the servers specified in -resolv.conf or the local named. In order to allow specification of either -IPv4 or IPv6 name servers, the -.BR ares_set_servers(3) -function must be used instead. -.TP 18 -.B ARES_OPT_DOMAINS -.B char **\fIdomains\fP; -.br -.B int \fIndomains\fP; -.br -The domains to search, instead of the domains specified in resolv.conf -or the domain derived from the kernel hostname variable. -.TP 18 -.B ARES_OPT_LOOKUPS -.B char *\fIlookups\fP; -.br -The lookups to perform for host queries. -.I lookups -should be set to a string of the characters "b" or "f", where "b" -indicates a DNS lookup and "f" indicates a lookup in the hosts file. -.TP 18 -.B ARES_OPT_SOCK_STATE_CB -.B void (*\fIsock_state_cb\fP)(void *data, int s, int read, int write); -.br -.B void *\fIsock_state_cb_data\fP; -.br -A callback function to be invoked when a socket changes state. -.I s -will be passed the socket whose state has changed; -.I read -will be set to true if the socket should listen for read events, and -.I write -will be set to true if the socket should listen for write events. -The value of -.I sock_state_cb_data -will be passed as the -.I data -argument. -.PP -The -.I flags -field should be the bitwise or of some subset of the following values: -.TP 23 -.B ARES_FLAG_USEVC -Always use TCP queries (the "virtual circuit") instead of UDP -queries. Normally, TCP is only used if a UDP query yields a truncated -result. -.TP 23 -.B ARES_FLAG_PRIMARY -Only query the first server in the list of servers to query. -.TP 23 -.B ARES_FLAG_IGNTC -If a truncated response to a UDP query is received, do not fall back -to TCP; simply continue on with the truncated response. -.TP 23 -.B ARES_FLAG_NORECURSE -Do not set the "recursion desired" bit on outgoing queries, so that the name -server being contacted will not try to fetch the answer from other servers if -it doesn't know the answer locally. Be aware that ares will not do the -recursion for you. Recursion must be handled by the application calling ares -if \fIARES_FLAG_NORECURSE\fP is set. -.TP 23 -.B ARES_FLAG_STAYOPEN -Do not close communications sockets when the number of active queries -drops to zero. -.TP 23 -.B ARES_FLAG_NOSEARCH -Do not use the default search domains; only query hostnames as-is or -as aliases. -.TP 23 -.B ARES_FLAG_NOALIASES -Do not honor the HOSTALIASES environment variable, which normally -specifies a file of hostname translations. -.TP 23 -.B ARES_FLAG_NOCHECKRESP -Do not discard responses with the SERVFAIL, NOTIMP, or REFUSED -response code or responses whose questions don't match the questions -in the request. Primarily useful for writing clients which might be -used to test or debug name servers. +service channel. The caller should invoke \fIares_destroy(3)\fP on the handle +when the channel is no longer needed. + +The \fIares_init_options(3)\fP function is provide to offer more init +alternatives. .SH RETURN VALUES -.I ares_init -or -.I ares_init_options -can return any of the following values: +\fIares_init(3)\fP can return any of the following values: .TP 14 .B ARES_SUCCESS Initialization succeeded. @@ -206,11 +63,12 @@ directives override one another. If more that one instance of either .I domain or .I search -directives is specified, the last occurence wins. For more information, +directives is specified, the last occurrence wins. For more information, please see the .BR resolv.conf (5) manual page. .SH SEE ALSO +.BR ares_init_options(3), .BR ares_destroy(3), .BR ares_dup(3), .BR ares_library_init(3), |