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c-ares/docs/ares_get_servers.3

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Avoid buffer overflow in RC4 loop comparison (#336) The rc4 function iterates over a buffer of size buffer_len who's maximum value is INT_MAX with a counter of type short that is not guaranteed to have maximum size INT_MAX. In circumstances where short is narrower than int and where buffer_len is larger than the maximum value of a short, it may be possible to loop infinitely as counter will overflow and never be greater than or equal to buffer_len. The solution is to make the comparison be between types of equal width. This commit defines counter as an int. Fix By: Fionn Fitzmaurice (@fionn)
4 years ago
.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
.\" Copyright (C) 2008-2010 by Daniel Stenberg
.\"
.\" Permission to use, copy, modify, and distribute this
.\" software and its documentation for any purpose and without
.\" fee is hereby granted, provided that the above copyright
.\" notice appear in all copies and that both that copyright
.\" notice and this permission notice appear in supporting
.\" documentation, and that the name of M.I.T. not be used in
.\" advertising or publicity pertaining to distribution of the
.\" software without specific, written prior permission.
.\" M.I.T. makes no representations about the suitability of
.\" this software for any purpose. It is provided "as is"
.\" without express or implied warranty.
.\"
provide SPDX identifiers and a REUSE CI job to verify All files have their licence and copyright information clearly identifiable. If not in the file header, they are set separately in .reuse/dep5. All used license texts are provided in LICENSES/
2 years ago
.\" SPDX-License-Identifier: MIT
.\"
Avoid buffer overflow in RC4 loop comparison (#336) The rc4 function iterates over a buffer of size buffer_len who's maximum value is INT_MAX with a counter of type short that is not guaranteed to have maximum size INT_MAX. In circumstances where short is narrower than int and where buffer_len is larger than the maximum value of a short, it may be possible to loop infinitely as counter will overflow and never be greater than or equal to buffer_len. The solution is to make the comparison be between types of equal width. This commit defines counter as an int. Fix By: Fionn Fitzmaurice (@fionn)
4 years ago
.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
.SH SYNOPSIS
.nf
docs: reformat/cleanup man pages SYNOPSIS sections (#494) To make them render "nicer" in both terminals and on the website. - Removes the bold - Removes .PP lines - Indents them more like proper code style Fix By: Daniel Stenberg (@bagder)
2 years ago
#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,
docs: reformat/cleanup man pages SYNOPSIS sections (#494) To make them render "nicer" in both terminals and on the website. - Removes the bold - Removes .PP lines - Indents them more like proper code style Fix By: Daniel Stenberg (@bagder)
2 years ago
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,
docs: reformat/cleanup man pages SYNOPSIS sections (#494) To make them render "nicer" in both terminals and on the website. - Removes the bold - Removes .PP lines - Indents them more like proper code style Fix By: Daniel Stenberg (@bagder)
2 years ago
struct ares_addr_port_node **\fIservers\fP)
Avoid buffer overflow in RC4 loop comparison (#336) The rc4 function iterates over a buffer of size buffer_len who's maximum value is INT_MAX with a counter of type short that is not guaranteed to have maximum size INT_MAX. In circumstances where short is narrower than int and where buffer_len is larger than the maximum value of a short, it may be possible to loop infinitely as counter will overflow and never be greater than or equal to buffer_len. The solution is to make the comparison be between types of equal width. This commit defines counter as an int. Fix By: Fionn Fitzmaurice (@fionn)
4 years ago
.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 AUTHOR
Implementation of this function and associated library internals are based
on code, comments and feedback provided in November and December of 2008 by
Daniel Stenberg, Gregor Jasny, Phil Blundell and Yang Tse, December 2009
by Cedric Bail, February 2010 by Jakub Hrozek. On March 2010 Yang Tse
shuffled all the bits and this function popped out.
.br
Copyright 1998 by the Massachusetts Institute of Technology.
.br
Copyright (C) 2008-2010 by Daniel Stenberg