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Add a preference to that when the window scaling options are not 

visible, we can still configure a scaling factor and therefore get
better TCP sequence analysis and see better stream graphs.

A single preference is used for any/all streams for which the true value
isn't known.  I tried to make it obvious when showing the calculated
window size that it came fromt he preference setting.  The default value
for this preference is off, i.e. it won't change existing behaviour.

This was discussed a little at Sharkfest and raised on the developers
list last week.

svn path=/trunk/; revision=43686
This commit is contained in:
Martin Mathieson 2012-07-12 23:57:51 +00:00
parent bc1b0fd21d
commit 99bd7cfe44
1 changed files with 73 additions and 5 deletions
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78
epan/dissectors/packet-tcp.c
View File

@ -64,6 +64,29 @@ static gboolean tcp_summary_in_tree = TRUE;
*/
static gboolean tcp_check_checksum = FALSE;
/*
* Window scaling values to be used when not known (set as a preference) */
enum scaling_window_value {
WindowScaling_NotKnown=-1,
WindowScaling_0=0,
WindowScaling_1,
WindowScaling_2,
WindowScaling_3,
WindowScaling_4,
WindowScaling_5,
WindowScaling_6,
WindowScaling_7,
WindowScaling_8,
WindowScaling_9,
WindowScaling_10,
WindowScaling_11,
WindowScaling_12,
WindowScaling_13,
WindowScaling_14
};
static gint tcp_default_window_scaling = (gint)WindowScaling_NotKnown;
extern FILE* data_out_file;
static int proto_tcp = -1;
@ -4210,6 +4233,12 @@ dissect_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
if (tcpd && (tcpd->fwd->win_scale>=0)) {
(tcph->th_win)<<=tcpd->fwd->win_scale;
}
else {
/* Don't have it stored, so use preference setting instead! */
if (tcp_default_window_scaling>=0) {
(tcph->th_win)<<=tcp_default_window_scaling;
}
}
}
/* Compute the sequence number of next octet after this segment. */
@ -4339,8 +4368,22 @@ dissect_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
switch (tcpd->fwd->win_scale) {
case -1:
scaled_pi = proto_tree_add_int_format(tcp_tree, hf_tcp_window_size_scalefactor, tvb, offset + 14, 2, tcpd->fwd->win_scale, "Window size scaling factor: %d (unknown)", tcpd->fwd->win_scale);
PROTO_ITEM_SET_GENERATED(scaled_pi);
{
gint16 win_scale = tcpd->fwd->win_scale;
gboolean override_with_pref = FALSE;
/* Use preference setting (if set) */
if (tcp_default_window_scaling != WindowScaling_NotKnown) {
win_scale = tcp_default_window_scaling;
override_with_pref = TRUE;
}
scaled_pi = proto_tree_add_int_format(tcp_tree, hf_tcp_window_size_scalefactor, tvb, offset + 14, 2,
win_scale, "Window size scaling factor: %d (%s)",
win_scale,
(override_with_pref) ? "missing - taken from preference" : "unkown");
PROTO_ITEM_SET_GENERATED(scaled_pi);
}
break;
case -2:
@ -5528,6 +5571,28 @@ proto_register_tcp(void)
&ett_tcp_checksum,
&ett_tcp_process_info
};
static enum_val_t window_scaling_vals[] = {
{"not-known", "Not known", WindowScaling_NotKnown},
{"0", "0 (no scaling)", WindowScaling_0},
{"1", "1 (multiply by 2)", WindowScaling_1},
{"2", "2 (multiply by 4)", WindowScaling_2},
{"3", "3 (multiply by 8)", WindowScaling_3},
{"4", "4 (multiply by 16)", WindowScaling_4},
{"5", "5 (multiply by 32)", WindowScaling_5},
{"6", "6 (multiply by 64)", WindowScaling_6},
{"7", "7 (multiply by 128)", WindowScaling_7},
{"8", "8 (multiply by 256)", WindowScaling_8},
{"9", "9 (multiply by 512)", WindowScaling_9},
{"10", "10 (multiply by 1024)", WindowScaling_10},
{"11", "11 (multiply by 2048)", WindowScaling_11},
{"12", "12 (multiply by 4096)", WindowScaling_12},
{"13", "13 (multiply by 8192)", WindowScaling_13},
{"14", "14 (multiply by 16384)", WindowScaling_14},
{NULL, NULL, -1}
};
module_t *tcp_module;
proto_tcp = proto_register_protocol("Transmission Control Protocol",
@ -5564,10 +5629,13 @@ proto_register_tcp(void)
"Make the TCP dissector use relative sequence numbers instead of absolute ones. "
"To use this option you must also enable \"Analyze TCP sequence numbers\". ",
&tcp_relative_seq);
prefs_register_enum_preference(tcp_module, "default_window_scaling",
"Scaling factor to use when not available from capture",
"Make the TCP dissector use this scaling factor for streams where the signalled scaling factor "
"is not visible in the capture",
&tcp_default_window_scaling, window_scaling_vals, FALSE);
/* We now have tcp.window_size_value and tcp.window_size, so no need
* anymore for the preference window_scaling
*/
/* Presumably a retired, unconditional version of what has been added back with the preference above... */
prefs_register_obsolete_preference(tcp_module, "window_scaling");
prefs_register_bool_preference(tcp_module, "track_bytes_in_flight",