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c-ares/docs/ares_save_options.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.
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_SAVE_OPTIONS 3 "5 March 2010"
.SH NAME
ares_save_options \- Save configuration values obtained from 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>
const is fine on ares__channel_[un]lock (#758) at https://github.com/c-ares/c-ares/pull/601#issuecomment-1801935063 you chose not to scatter `const` on the public interface because of the plan - now realised - to add threading to c-ares, and in the expectation that even read operations would need to lock the mutex. But the threading implementation has a _pointer_ to a mutex inside the ares channel and as I understand it, that means that it is just fine to mark `ares__channel_lock` (and `ares__channel_unlock`) as taking a `const` channel. It is the pointed-to mutex that is not constant, but C does not propagate `const`-ness through pointers. This PR sprinkles const where appropriate on public interfaces. Fix By: David Hotham (@dimbleby)
6 months ago
int ares_save_options(const 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_options *\fIoptions\fP, int *\fIoptmask\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_save_options(3)\fP function saves the channel data identified by
.IR channel ,
into the options struct identified by
.IR options ,
and saves the mask of options which are set to the integer
pointer (passed by reference) identified by
.IR optmask .
The resultant options and optmask are then able to be
passed directly to ares_init_options. When the options
are no longer needed, ares_destroy_options should be called
to free any associated memory.
.SH RETURN VALUES
.B ares_save_options(3)
can return any of the following values:
.TP 15
.B ARES_SUCCESS
The channel data was successfully stored
.TP 15
.B ARES_ENOMEM
The memory was exhausted
.TP 15
.B ARES_ENODATA
const is fine on ares__channel_[un]lock (#758) at https://github.com/c-ares/c-ares/pull/601#issuecomment-1801935063 you chose not to scatter `const` on the public interface because of the plan - now realised - to add threading to c-ares, and in the expectation that even read operations would need to lock the mutex. But the threading implementation has a _pointer_ to a mutex inside the ares channel and as I understand it, that means that it is just fine to mark `ares__channel_lock` (and `ares__channel_unlock`) as taking a `const` channel. It is the pointed-to mutex that is not constant, but C does not propagate `const`-ness through pointers. This PR sprinkles const where appropriate on public interfaces. Fix By: David Hotham (@dimbleby)
6 months ago
The channel data identified by
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
.IR channel
were invalid.
.SH NOTE
Since c-ares 1.6.0 the ares_options struct has been "locked" meaning that it
won't be extended to cover new functions. This function will remain
functioning, but it can only return config data that can be represented in
this config struct, which may no longer be the complete set of config
options. \fBares_dup(3)\fP will not have that restriction.
The ares_options struct can not handle potential IPv6 name servers the
`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
ares channel might be configured to use. The \fBares_save_options(3)\fP function
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
will only return IPv4 servers, if any. In order to retrieve all name servers
`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
an ares channel might be using, the \fBares_get_servers(3)\fP function must be
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
used instead.
.SH SEE ALSO
.BR ares_destroy_options (3),
.BR ares_init_options (3),
.BR ares_get_servers (3),
.BR ares_dup (3)
.SH AVAILABILITY
ares_save_options(3) was added in c-ares 1.4.0