508 lines
17 KiB
C
508 lines
17 KiB
C
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/*
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* ng_parse.h
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*
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* Copyright (c) 1999 Whistle Communications, Inc.
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* All rights reserved.
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*
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* Subject to the following obligations and disclaimer of warranty, use and
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* redistribution of this software, in source or object code forms, with or
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* without modifications are expressly permitted by Whistle Communications;
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* provided, however, that:
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* 1. Any and all reproductions of the source or object code must include the
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* copyright notice above and the following disclaimer of warranties; and
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* 2. No rights are granted, in any manner or form, to use Whistle
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* Communications, Inc. trademarks, including the mark "WHISTLE
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* COMMUNICATIONS" on advertising, endorsements, or otherwise except as
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* such appears in the above copyright notice or in the software.
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*
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* THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
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* TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
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* REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
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* INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
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* WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
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* REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
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* SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
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* IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
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* RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
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* WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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* PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* Author: Archie Cobbs <archie@whistle.com>
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*
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* $Whistle: ng_parse.h,v 1.2 1999/11/29 01:43:48 archie Exp $
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* $FreeBSD$
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*/
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#ifndef _NETGRAPH_PARSE_H_
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#define _NETGRAPH_PARSE_H_
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/*
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This defines a library of routines for converting between various C
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language types in binary form and ASCII strings. Types are user
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definable. Several pre-defined types are supplied, for some common
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C types: structures, variable and fixed length arrays, integer types,
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variable and fixed length strings, IP addresses, etc.
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A netgraph node type may provide a list of types that correspond to
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the structures it expects to send and receive in the arguments field
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of a control message. This allows these messages to be converted
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between their native binary form and the corresponding ASCII form.
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A future use of the ASCII form may be for inter-machine communication
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of control messages, because the ASCII form is machine independent
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whereas the native binary form is not.
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Syntax
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------
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Structures:
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'{' [ <name>=<value> ... ] '}'
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Omitted fields have their default values by implication.
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The order in which the fields are specified does not matter.
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Arrays:
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'[' [ [index=]<value> ... ] ']'
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Element value may be specified with or without the "<index>=" prefix;
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If omitted, the index after the previous element is used.
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Omitted fields have their default values by implication.
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Strings:
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"foo bar blah\r\n"
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That is, strings are specified just like C strings. The usual
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backslash escapes are accepted.
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Other simple types (integers, IP addresses) have their obvious forms.
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Example
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-------
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Suppose we have a netgraph command that takes as an argument
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a 'struct foo' shown below. Here is an example of a possible
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value for the structure, and the corresponding ASCII encoding
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of that value:
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Structure Binary value
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--------- ------------
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struct foo {
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struct in_addr ip; 01 02 03 04
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int bar; 00 00 00 00
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char label[8]; 61 62 63 0a 00 00 00 00
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u_char alen; 03 00
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short ary[0]; 05 00 00 00 0a 00
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};
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ASCII value
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-----------
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{ ip=1.2.3.4 label="abc\n" alen=3 ary=[ 5 2=10 ] }
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Note that omitted fields and array elements get their default
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values ("bar" and ary[2]), and that the alignment is handled
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automatically (the extra 00 byte after "num"). Also, since byte
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order and alignment are inherently machine dependent, so is this
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conversion process. The above example shows an x86 (little
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endian) encoding. Also the above example is tricky because the
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structure is variable length, depending on 'alen', the number of
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elements in the array 'ary'.
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Here is how one would define a parse type for the above structure,
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subclassing the pre-defined types below. We construct the type in
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a 'bottom up' fashion, defining each field's type first, then the
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type for the whole structure ('//' comments used to avoid breakage).
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// Super-type info for 'label' field
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struct ng_parse_fixedstring_info foo_label_info = { 8 };
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// Parse type for 'label' field
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struct ng_parse_type foo_label_type = {
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&ng_parse_fixedstring_type // super-type
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&foo_label_info // super-type info
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};
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#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
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// Function to compute the length of the array 'ary', which
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// is variable length, depending on the previous field 'alen'.
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// Upon entry 'buf' will be pointing at &ary[0].
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int
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foo_ary_getLength(const struct ng_parse_type *type,
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const u_char *start, const u_char *buf)
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{
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const struct foo *f;
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f = (const struct foo *)(buf - OFFSETOF(struct foo, ary));
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return f->alen;
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}
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// Super-type info for 'ary' field
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struct ng_parse_array_info foo_ary_info = {
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&ng_parse_int16_type, // element type
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&foo_ary_getLength // func to get array length
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}
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// Parse type for 'ary' field
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struct ng_parse_type foo_ary_type = {
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&ng_parse_array_type, // super-type
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&foo_ary_info // super-type info
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};
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// Super-type info for struct foo
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struct ng_parse_struct_info foo_fields = {
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{ "ip", &ng_parse_ipaddr_type },
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{ "bar", &ng_parse_int32_type },
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{ "label", &foo_label_type },
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{ "alen", &ng_parse_int8_type },
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{ "ary", &foo_ary_type },
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{ NULL }
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};
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// Parse type for struct foo
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struct ng_parse_type foo_type = {
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&ng_parse_struct_type, // super-type
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&foo_fields // super-type info
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};
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To define a type, you can define it as a sub-type of a predefined
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type as shown above, possibly overriding some of the predefined
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type's methods, or define an entirely new syntax, with the restriction
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that the ASCII representation of your type's value must not contain
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any whitespace or any of these characters: { } [ ] = "
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See ng_ksocket.c for an example of how to do this for 'struct sockaddr'.
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See ng_parse.c to see implementations of the pre-defined types below.
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*/
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/************************************************************************
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METHODS REQUIRED BY A TYPE
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************************************************************************/
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/*
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* Three methods are required for a type. These may be given explicitly
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* or, if NULL, inherited from the super-type. The 'getDefault' method
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* is always optional; the others are required if there is no super-type.
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*/
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struct ng_parse_type;
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/*
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* Convert ASCII to binary according to the supplied type.
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*
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* The ASCII characters begin at offset *off in 'string'. The binary
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* representation is put into 'buf', which has at least *buflen bytes.
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* 'start' points to the first byte output by ng_parse() (ie, start <= buf).
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*
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* Upon return, *buflen contains the length of the new binary data, and
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* *off is updated to point just past the end of the parsed range of
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* characters, or, in the case of an error, to the offending character(s).
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*
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* Return values:
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* 0 Success; *buflen holds the length of the data
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* and *off points just past the last char parsed.
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* EALREADY Field specified twice
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* ENOENT Unknown field
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* E2BIG Array or character string overflow
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* ERANGE Output was longer than *buflen bytes
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* EINVAL Parse failure or other invalid content
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* ENOMEM Out of memory
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* EOPNOTSUPP Mandatory array/structure element missing
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*/
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typedef int ng_parse_t(const struct ng_parse_type *type, const char *string,
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int *off, const u_char *start,
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u_char *buf, int *buflen);
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/*
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* Convert binary to ASCII according to the supplied type.
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*
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* The results are put into 'buf', which is at least buflen bytes long.
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* *off points to the current byte in 'data' and should be updated
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* before return to point just past the last byte unparsed.
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*
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* Returns:
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* 0 Success
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* ERANGE Output was longer than buflen bytes
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*/
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typedef int ng_unparse_t(const struct ng_parse_type *type,
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const u_char *data, int *off, char *buf, int buflen);
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/*
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* Compute the default value according to the supplied type.
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*
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* Store the result in 'buf', which is at least *buflen bytes long.
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* Upon return *buflen contains the length of the output.
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*
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* Returns:
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* 0 Success
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* ERANGE Output was longer than *buflen bytes
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* EOPNOTSUPP Default value is not specified for this type
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*/
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typedef int ng_getDefault_t(const struct ng_parse_type *type,
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const u_char *start, u_char *buf, int *buflen);
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/*
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* Return the alignment requirement of this type. Zero is same as one.
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*/
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typedef int ng_getAlign_t(const struct ng_parse_type *type);
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/************************************************************************
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TYPE DEFINITION
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************************************************************************/
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/*
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* This structure describes a type, which may be a sub-type of another
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* type by pointing to it with 'supertype' and possibly omitting methods.
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* Typically the super-type requires some type-specific info, which is
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* supplied by the 'info' field.
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*
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* The 'private' field is ignored by all of the pre-defined types.
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* Sub-types may use it as they see fit.
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*
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* The 'getDefault' method may always be omitted (even if there is no
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* super-type), which means the value for any item of this type must
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* always be explicitly given.
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*/
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struct ng_parse_type {
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const struct ng_parse_type *supertype; /* super-type, if any */
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const void *info; /* type-specific info */
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void *private; /* client private info */
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ng_parse_t *parse; /* parse method */
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ng_unparse_t *unparse; /* unparse method */
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ng_getDefault_t *getDefault; /* get default value method */
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ng_getAlign_t *getAlign; /* get alignment */
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};
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/************************************************************************
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PRE-DEFINED TYPES
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************************************************************************/
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/*
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* STRUCTURE TYPE
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*
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* This type supports arbitrary C structures. The normal field alignment
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* rules for the local machine are applied. Fields are always parsed in
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* field order, no matter what order they are listed in the ASCII string.
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*
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* Default value: Determined on a per-field basis
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* Additional info: struct ng_parse_struct_info *
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*/
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extern const struct ng_parse_type ng_parse_struct_type;
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/* Each field has a name, type, and optional alignment override. If the
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override is non-zero, the alignment is determined from the field type.
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Note: add an extra struct ng_parse_struct_field with name == NULL
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to indicate the end of the list. */
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struct ng_parse_struct_info {
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struct ng_parse_struct_field {
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const char *name; /* field name */
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const struct ng_parse_type
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*type; /* field type */
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int alignment; /* override alignment */
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} fields[0];
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};
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/*
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* FIXED LENGTH ARRAY TYPE
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*
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* This type supports fixed length arrays, having any element type.
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*
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* Default value: As returned by getDefault for each index
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* Additional info: struct ng_parse_fixedarray_info *
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*/
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extern const struct ng_parse_type ng_parse_fixedarray_type;
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/*
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* Get the default value for the element at index 'index'. This method
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* may be NULL, in which case the default value is computed from the
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* element type. Otherwise, it should fill in the default value at *buf
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* (having size *buflen) and update *buflen to the length of the filled-in
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* value before return. If there is not enough routine return ERANGE.
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*/
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typedef int ng_parse_array_getDefault_t(const struct ng_parse_type *type,
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int index, const u_char *start,
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u_char *buf, int *buflen);
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struct ng_parse_fixedarray_info {
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const struct ng_parse_type *elementType;
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int length;
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ng_parse_array_getDefault_t *getDefault;
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};
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/*
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* VARIABLE LENGTH ARRAY TYPE
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*
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* Same as fixed length arrays, except that the length is determined
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* by a function instead of a constant value.
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*
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* Default value: Same as with fixed length arrays
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* Additional info: struct ng_parse_array_info *
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*/
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extern const struct ng_parse_type ng_parse_array_type;
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/*
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* Return the length of the array. If the array is a field in a structure,
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* all prior fields are guaranteed to be filled in already. Upon entry,
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* 'start' is equal to the first byte parsed in this run, while 'buf' points
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* to the first element of the array to be filled in.
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*/
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typedef int ng_parse_array_getLength_t(const struct ng_parse_type *type,
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const u_char *start, const u_char *buf);
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struct ng_parse_array_info {
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const struct ng_parse_type *elementType;
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ng_parse_array_getLength_t *getLength;
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ng_parse_array_getDefault_t *getDefault;
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};
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/*
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* ARBITRARY LENGTH STRING TYPE
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*
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* For arbirary length, NUL-terminated strings.
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*
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* Default value: Empty string
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* Additional info: None required
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*/
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extern const struct ng_parse_type ng_parse_string_type;
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/*
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* BOUNDED LENGTH STRING TYPE
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*
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* These are strings that have a fixed-size buffer, and always include
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* a terminating NUL character.
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*
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* Default value: Empty string
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* Additional info: struct ng_parse_fixedstring_info *
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*/
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extern const struct ng_parse_type ng_parse_fixedstring_type;
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struct ng_parse_fixedstring_info {
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int bufSize; /* size of buffer (including NUL) */
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};
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/*
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* COMMONLY USED BOUNDED LENGTH STRING TYPES
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*/
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extern const struct ng_parse_type ng_parse_nodebuf_type; /* NG_NODELEN + 1 */
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extern const struct ng_parse_type ng_parse_hookbuf_type; /* NG_HOOKLEN + 1 */
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extern const struct ng_parse_type ng_parse_pathbuf_type; /* NG_PATHLEN + 1 */
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extern const struct ng_parse_type ng_parse_typebuf_type; /* NG_TYPELEN + 1 */
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extern const struct ng_parse_type ng_parse_cmdbuf_type; /* NG_CMDSTRLEN + 1 */
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/*
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* INTEGER TYPES
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*
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* Default value: 0
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* Additional info: None required
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*/
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extern const struct ng_parse_type ng_parse_int8_type;
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extern const struct ng_parse_type ng_parse_int16_type;
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extern const struct ng_parse_type ng_parse_int32_type;
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extern const struct ng_parse_type ng_parse_int64_type;
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/*
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* IP ADDRESS TYPE
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*
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* Default value: 0.0.0.0
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* Additional info: None required
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*/
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extern const struct ng_parse_type ng_parse_ipaddr_type;
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/*
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* VARIABLE LENGTH BYTE ARRAY TYPE
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*
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* The bytes are displayed in hex. The ASCII form may be either an
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* array of bytes or a string constant, in which case the array is
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* zero-filled after the string bytes.
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*
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* Default value: All bytes are zero
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* Additional info: ng_parse_array_getLength_t *
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*/
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extern const struct ng_parse_type ng_parse_bytearray_type;
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/*
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* NETGRAPH CONTROL MESSAGE TYPE
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*
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* This is the parse type for a struct ng_mesg.
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*
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* Default value: All fields zero
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* Additional info: None required
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*/
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extern const struct ng_parse_type ng_parse_ng_mesg_type;
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/************************************************************************
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CONVERSTION AND PARSING ROUTINES
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************************************************************************/
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/* Tokens for parsing structs and arrays */
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enum ng_parse_token {
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T_LBRACE, /* '{' */
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T_RBRACE, /* '}' */
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T_LBRACKET, /* '[' */
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T_RBRACKET, /* ']' */
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T_EQUALS, /* '=' */
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T_STRING, /* string in double quotes */
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T_ERROR, /* error parsing string in double quotes */
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T_WORD, /* anything else containing no whitespace */
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T_EOF, /* end of string reached */
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};
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/*
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* See typedef ng_parse_t for definition
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*/
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extern int ng_parse(const struct ng_parse_type *type, const char *string,
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int *off, u_char *buf, int *buflen);
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/*
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* See typedef ng_unparse_t for definition (*off assumed to be zero).
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*/
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extern int ng_unparse(const struct ng_parse_type *type,
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const u_char *data, char *buf, int buflen);
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/*
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* See typedef ng_getDefault_t for definition
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*/
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extern int ng_parse_getDefault(const struct ng_parse_type *type,
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u_char *buf, int *buflen);
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/*
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* Parse a token: '*startp' is the offset to start looking. Upon
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* successful return, '*startp' equals the beginning of the token
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* and '*lenp' the length. If error, '*startp' points at the
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* offending character(s).
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*/
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extern enum ng_parse_token ng_parse_get_token(const char *s,
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int *startp, int *lenp);
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/*
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* Like above, but specifically for getting a string token and returning
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* the string value. The string token must be enclosed in double quotes
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* and the normal C backslash escapes are recognized. The caller must
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* eventually free() the returned result. Returns NULL if token is
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* not a string token, or parse or other error.
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*/
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extern char *ng_get_string_token(const char *s, int *startp, int *lenp);
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/*
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* Convert a raw string into a doubly-quoted string including any
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* necessary backslash escapes. Caller must free the result.
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* Returns NULL if ENOMEM.
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*/
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extern char *ng_encode_string(const char *s);
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#endif /* _NETGRAPH_PARSE_H_ */
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