A C library for asynchronous DNS requests (grpc依赖)
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.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
.\" Copyright (C) 2008-2010 by Daniel Stenberg
.\" SPDX-License-Identifier: MIT
.\"
.TH ARES_GET_SERVERS 3 "5 March 2010"
.SH NAME
ares_get_servers, ares_get_servers_ports \- Retrieve name servers from an initialized ares_channel (deprecated)
.SH SYNOPSIS
.nf
#include <ares.h>
`ares_channel` -> `ares_channel_t *`: don't bury the pointer (#595) `ares_channel` is defined as `typedef struct ares_channeldata *ares_channel;`. The problem with this, is it embeds the pointer into the typedef, which means an `ares_channel` can never be declared as `const` as if you write `const ares_channel channel`, that expands to `struct ares_channeldata * const ares_channel` and not `const struct ares_channeldata *channel`. We will now typedef `ares_channel_t` as `typedef struct ares_channeldata ares_channel_t;`, so if you write `const ares_channel_t *channel`, it properly expands to `const struct ares_channeldata *channel`. We are maintaining the old typedef for API compatibility with existing integrations, and due to typedef expansion this should not even cause any compiler warnings for existing code. There are no ABI implications with this change. I could be convinced to keep existing public functions as `ares_channel` if a sufficient argument exists, but internally we really need make this change for modern best practices. This change will allow us to internally use `const ares_channel_t *` where appropriate. Whether or not we decide to change any public interfaces to use `const` may require further discussion on if there might be ABI implications (I don't think so, but I'm also not 100% sure what a compiler internally does with `const` when emitting machine code ... I think more likely ABI implications would occur going the opposite direction). FYI, This PR was done via a combination of sed and clang-format, the only manual code change was the addition of the new typedef, and a couple doc fixes :) Fix By: Brad House (@bradh352)
1 year ago
int ares_get_servers(ares_channel_t *\fIchannel\fP,
struct ares_addr_node **\fIservers\fP)
`ares_channel` -> `ares_channel_t *`: don't bury the pointer (#595) `ares_channel` is defined as `typedef struct ares_channeldata *ares_channel;`. The problem with this, is it embeds the pointer into the typedef, which means an `ares_channel` can never be declared as `const` as if you write `const ares_channel channel`, that expands to `struct ares_channeldata * const ares_channel` and not `const struct ares_channeldata *channel`. We will now typedef `ares_channel_t` as `typedef struct ares_channeldata ares_channel_t;`, so if you write `const ares_channel_t *channel`, it properly expands to `const struct ares_channeldata *channel`. We are maintaining the old typedef for API compatibility with existing integrations, and due to typedef expansion this should not even cause any compiler warnings for existing code. There are no ABI implications with this change. I could be convinced to keep existing public functions as `ares_channel` if a sufficient argument exists, but internally we really need make this change for modern best practices. This change will allow us to internally use `const ares_channel_t *` where appropriate. Whether or not we decide to change any public interfaces to use `const` may require further discussion on if there might be ABI implications (I don't think so, but I'm also not 100% sure what a compiler internally does with `const` when emitting machine code ... I think more likely ABI implications would occur going the opposite direction). FYI, This PR was done via a combination of sed and clang-format, the only manual code change was the addition of the new typedef, and a couple doc fixes :) Fix By: Brad House (@bradh352)
1 year ago
int ares_get_servers_ports(ares_channel_t *\fIchannel\fP,
struct ares_addr_port_node **\fIservers\fP)
.fi
.SH DESCRIPTION
The \fBares_get_servers(3)\fP function retrieves name servers configuration
from the
channel data identified by
.IR channel ,
as a linked list of ares_addr_node structs storing a pointer to the first
node at the address specified by
.IR servers .
The \fBares_get_servers_ports(3)\fP function also retrieves any per-server
port information that may have been previously configured, returning a linked
list of ares_addr_port structures.
Function caller may traverse the returned name server linked list, or may use
it directly as suitable input for the \fBares_set_servers(3)\fP /
\fBares_set_servers_ports(3)\fP functions, but
shall not shrink or extend the list on its own.
Each node of the name server linked list is stored in memory dynamically
allocated and managed by c-ares. It is the caller's responsibility to free
the resulting linked list, using \fBares_free_data(3)\fP , once the caller
does not need it any longer.
This function is capable of handling IPv4 and IPv6 name server
addresses simultaneously, rendering \fBares_save_options(3)\fP with
optmask \fBARES_OPT_SERVERS\fP functionally obsolete except for
IPv4-only name server usage.
.SH RETURN VALUES
This function may return any of the following values:
.TP 15
.B ARES_SUCCESS
The name servers configuration was successfully retrieved
.TP 15
.B ARES_ENOMEM
The memory was exhausted
.TP 15
.B ARES_ENODATA
The channel data identified by
.IR channel
was invalid.
.SH SEE ALSO
.BR ares_set_servers (3),
.BR ares_init_options (3),
.BR ares_save_options(3)
.SH AVAILABILITY
\fBares_get_servers(3)\fP was added in c-ares 1.7.1;
\fBares_get_servers_ports(3)\fP was added in c-ares 1.11.0.
.SH NOTES
As of c-ares 1.24, these functions are deprecated due to their lack of ability
to store the entire server configuration. Use \fBares_get_servers_csv(3)\fP.