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Update README.developer to take into account the disappearance of 

FT_EBCDIC and the addition of support for character encodings.

svn path=/trunk/; revision=39190
This commit is contained in:
Guy Harris 2011-09-29 22:40:32 +00:00
parent 8cc93538e2
commit f45ade999f
1 changed files with 49 additions and 31 deletions
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doc/README.developer
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@ -1127,7 +1127,7 @@ FIELDABBREV The abbreviated name for the header field. (NO SPACES)
FIELDTYPE FT_NONE, FT_BOOLEAN, FT_UINT8, FT_UINT16, FT_UINT24,
FT_UINT32, FT_UINT64, FT_INT8, FT_INT16, FT_INT24, FT_INT32,
FT_INT64, FT_FLOAT, FT_DOUBLE, FT_ABSOLUTE_TIME,
FT_RELATIVE_TIME, FT_STRING, FT_STRINGZ, FT_EBCDIC, FT_EUI64
FT_RELATIVE_TIME, FT_STRING, FT_STRINGZ, FT_EUI64,
FT_UINT_STRING, FT_ETHER, FT_BYTES, FT_UINT_BYTES, FT_IPv4,
FT_IPv6, FT_IPXNET, FT_FRAMENUM, FT_PROTOCOL, FT_GUID, FT_OID
FIELDDISPLAY For FT_UINT{8,16,24,32,64} and FT_INT{8,16,24,32,64):
@ -1730,23 +1730,6 @@ The type of value this field holds. The current field types are:
displayed as the date, followed by the time, as
hours, minutes, and seconds with 9 digits after
the decimal point.
Two absolute time encodings may be specified
with proto_tree_add_item():
ENC_TIME_TIMESPEC: Seconds (4 bytes) and
nanoseconds (4 bytes) of time since January 1,
1970, midnight UTC.
ENC_TIME_NTP: NTP timestamps are represented as
a 64-bit unsigned fixed-point number, in seconds
relative to 0h on 1 January 1900. The integer
part is in the first 32 bits and the fraction
part in the last 32 bits.
The encoding must be logically ORed with
ENC_BIG_ENDIAN or ENC_LITTLE_ENDIAN as
appropriate.
FT_RELATIVE_TIME Seconds (4 bytes) and nanoseconds (4 bytes)
of time relative to an arbitrary time.
displayed as seconds and 9 digits
@ -1762,10 +1745,6 @@ The type of value this field holds. The current field types are:
However if the length given in the call
is -1, then the length used is that
returned by calling tvb_strsize().
FT_EBCDIC A string of characters, not necessarily
NUL-terminated, but possibly NUL-padded.
The data from the packet is converted from
EBCDIC to ASCII before displaying to the user.
FT_UINT_STRING A counted string of characters, consisting
of a count (represented as an integral value,
of width given in the proto_tree_add_item()
@ -2354,13 +2333,52 @@ proto_tree_add_item is used when you wish to do no special formatting.
The item added to the GUI tree will contain the name (as passed in the
proto_register_*() function) and a value. The value will be fetched
from the tvbuff by proto_tree_add_item(), based on the type of the field
and, for integral and Boolean fields, the byte order of the value; the
byte order, for items for which that's relevant, is specified by the
'encoding' argument, which is ENC_LITTLE_ENDIAN if the value is
little-endian and ENC_BIG_ENDIAN if it is big-endian. If the byte order
is not relevant, use ENC_NA (Not Applicable). For some field types,
additional encoding information, such as the character encoding for
character strings, are supported.
and the encoding of the value as specified by the "encoding" argument.
For protocols, FT_NONE fields, FT_BYTES fields, FT_EUI64 fields, FT_IPv6
fields, FT_IPXNET fields, and FT_OID fields, the encoding is not
relevant; the 'encoding' argument should be ENC_NA (Not Applicable).
For integral, floating-point, Boolean, and FT_GUID fields, the encoding
specifies the byte order of the value; the 'encoding' argument should be
is ENC_LITTLE_ENDIAN if the value is little-endian and ENC_BIG_ENDIAN if
it is big-endian.
For FT_IPv4 fields, the encoding also specifies the byte order of the
value. In almost all cases, the encoding is in network byte order,
hence big-endian, but in at least one protocol dissected by Wireshark,
at least one IPv4 address is byte-swapped, so it's in little-endian
order.
For string fields, the encoding specifies the character set used for the
string and the way individual code points in that character set are
encoded. For FT_UINT_STRING fields, the byte order of the count must be
specified; when support for UTF-16 encoding is added, the byte order of
the encoding will also have to be specified. In other cases, either
ENC_NA, ENC_BIG_ENDIAN, or ENC_LITTLE_ENDIAN can be specified. The
character encodings that are currently supported are:
ENC_UTF_8 - UTF-8
ENC_ASCII - ASCII (currently treated as UTF-8; in the future,
all bytes with the 8th bit set will be treated as
errors)
ENC_EBCDIC - EBCDIC
Other encodings will be added in the future.
For FT_ABSOLUTE_TIME fields, the encoding specifies the form in which
the time stamp is specified, as well as its byte order. The time stamp
encodings that are curretly supported are:
ENC_TIME_TIMESPEC - seconds (4 bytes) and nanoseconds (4 bytes)
of time since January 1, 1970, midnight UTC.
ENC_TIME_NTP - an NTP timestamp, represented as a 64-bit
unsigned fixed-point number, in seconds relative to 0h
on 1 January 1900. The integer part is in the first 32
bits and the fraction part in the last 32 bits.
For other types, there is no support for proto_tree_add_item().
Now that definitions of fields have detailed information about bitfield
fields, you can use proto_tree_add_item() with no extra processing to
@ -3856,7 +3874,7 @@ static hf_register_info hf[] = {
};
/**
* Dissect a buffer containing C strings.
* Dissect a buffer containing ASCII C strings.
*
* @param tvb The buffer to dissect.
* @param pinfo Packet Info.
@ -3882,7 +3900,7 @@ static void dissect_cstr(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)
if (tree) {
proto_tree_add_item(tree, hf_cstring, tvb, offset, len,
ENC_NA);
ENC_ASCII|ENC_NA);
}
offset += (guint)len;
}