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c-ares/docs/ares_init.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) 2004-2010 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/
1 year 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_INIT 3 "5 March 2010"
.SH NAME
ares_init \- Initialize a resolver channel
.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_init(ares_channel_t **\fIchannelptr\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_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 \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
\fIares_init(3)\fP can return any of the following values:
.TP 14
.B ARES_SUCCESS
Initialization succeeded.
.TP 14
.B ARES_EFILE
A configuration file could not be read.
.TP 14
.B ARES_ENOMEM
The process's available memory was exhausted.
.TP 14
.B ARES_ENOTINITIALIZED
c-ares library initialization not yet performed.
.SH NOTES
When initializing from
.B /etc/resolv.conf,
.BR ares_init (3)
reads the
.I domain
and
.I search
directives to allow lookups of short names relative to the domains
specified. The
.I domain
and
.I search
directives override one another. If more that one instance of either
.I domain
or
.I search
directives is specified, the last occurrence wins. For more information,
please see the
.BR resolv.conf (5)
manual page.
.SH SEE ALSO
docs: provide better man page references When referring to another c-ares function use \fI function(3) \fP to let the webpage rendering find and cross-link them appropriately. SEE ALSO references should be ".BR name (3),", with a space before the open parenthesis. This helps the manpage to HTML renderer. Closes #565
1 year ago
.BR ares_init_options (3),
Release 1.22.0 (#616)
1 year ago
.BR ares_reinit (3),
docs: provide better man page references When referring to another c-ares function use \fI function(3) \fP to let the webpage rendering find and cross-link them appropriately. SEE ALSO references should be ".BR name (3),", with a space before the open parenthesis. This helps the manpage to HTML renderer. Closes #565
1 year ago
.BR ares_destroy (3),
.BR ares_dup (3),
.BR ares_library_init (3),
.BR ares_set_servers (3)
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
.SH AUTHOR
Greg Hudson, MIT Information Systems
.br
Copyright 1998 by the Massachusetts Institute of Technology.
.br
Copyright (C) 2004-2010 by Daniel Stenberg.