osmith
/
wireshark
forked from osmocom/wireshark
1
0
Fork 0
Code Pull Requests Releases Wiki Activity

Update the "Following Conversations" section to use se_alloc() instead of GMemChunks. 

Also: add information about the conversation_set_dissector() function.

svn path=/trunk/; revision=35185
This commit is contained in:
Bill Meier 2010-12-14 14:23:27 +00:00
parent 9da77c4716
commit 2798debd90
1 changed files with 47 additions and 63 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

110
doc/README.developer
View File

@ -2937,25 +2937,29 @@ address:port combinations. A conversation is not sensitive to the direction of
the packet. The same conversation will be returned for a packet bound from
ServerA:1000 to ClientA:2000 and the packet from ClientA:2000 to ServerA:1000.
There are five routines that you will use to work with a conversation:
2.2.1 Conversation Routines
There are six routines that you will use to work with a conversation:
conversation_new, find_conversation, conversation_add_proto_data,
conversation_get_proto_data, and conversation_delete_proto_data.
conversation_get_proto_data, conversation_delete_proto_data,
and conversation_set_dissector.
2.2.1 The conversation_init function.
2.2.1.1 The conversation_init function.
This is an internal routine for the conversation code. As such you
will not have to call this routine. Just be aware that this routine is
called at the start of each capture and before the packets are filtered
with a display filter. The routine will destroy all stored
conversations. This routine does NOT clean up any data pointers that are
passed in the conversation_new 'data' variable. You are responsible for
this clean up if you pass a malloc'ed pointer in this variable.
passed in the conversation_add_proto_data 'data' variable. You are
responsible for this clean up if you pass a malloc'ed pointer
in this variable.
See item 2.2.8 for more information about the 'data' pointer.
See item 2.2.1.5 for more information about use of the 'data' pointer.
2.2.2 The conversation_new function.
2.2.1.2 The conversation_new function.
This routine will create a new conversation based upon two address/port
pairs. If you want to associate with the conversation a pointer to a
@ -3001,7 +3005,7 @@ packet indicates that, later in the capture, a conversation will be
created using certain addresses and ports, in the case where the packet
doesn't specify the addresses and ports of both sides.
2.2.3 The find_conversation function.
2.2.1.3 The find_conversation function.
Call this routine to look up a conversation. If no conversation is found,
the routine will return a NULL value.
@ -3051,7 +3055,7 @@ any "wildcarded" address and the "port_b" port will be treated as
matching any "wildcarded" port.
2.2.4 The find_or_create_conversation function.
2.2.1.4 The find_or_create_conversation function.
This convenience function will create find an existing conversation (by calling
find_conversation()) and, if a conversation does not already exist, create a
@ -3069,7 +3073,7 @@ conversation_new() are taken from the pinfo structure (as is commonly done)
and no 'options' are used.
2.2.5 The conversation_add_proto_data function.
2.2.1.5 The conversation_add_proto_data function.
Once you have created a conversation with conversation_new, you can
associate data with it using this function.
@ -3088,11 +3092,14 @@ Where:
unique protocol number created with proto_register_protocol. Protocols
are typically registered in the proto_register_XXXX section of your
dissector. "data" is a pointer to the data you wish to associate with the
conversation. Using the protocol number allows several dissectors to
conversation. "data" usually points to "se_alloc'd" memory; the
memory will be automatically freed each time a new dissection begins
and thus need not be managed (freed) by the dissector.
Using the protocol number allows several dissectors to
associate data with a given conversation.
2.2.6 The conversation_get_proto_data function.
2.2.1.6 The conversation_get_proto_data function.
After you have located a conversation with find_conversation, you can use
this function to retrieve any data associated with it.
@ -3111,12 +3118,12 @@ typically in the proto_register_XXXX portion of a dissector. The function
returns a pointer to the data requested, or NULL if no data was found.
2.2.7 The conversation_delete_proto_data function.
2.2.1.7 The conversation_delete_proto_data function.
After you are finished with a conversation, you can remove your association
with this function. Please note that ONLY the conversation entry is
removed. If you have allocated any memory for your data, you must free it
as well.
removed. If you have allocated any memory for your data (other than with se_alloc),
you must free it as well.
The conversation_delete_proto_data prototype:
@ -3130,8 +3137,22 @@ Where:
is a unique protocol number created with proto_register_protocol,
typically in the proto_register_XXXX portion of a dissector.
2.2.1.8 The conversation_set_dissector function
2.2.8 Using timestamps relative to the conversation
This function sets the protocol dissector to be invoked whenever
conversation parameters (addresses, port_types, ports, etc) are matched
during the dissection of a packet.
The conversation_set_dissector prototype:
void conversation_set_dissector(conversation_t *conversation, const dissector_handle_t handle);
Where:
conversation_t *conv = the conversation in question
const dissector_handle_t handle = the dissector handle.
2.2.2 Using timestamps relative to the conversation
There is a framework to calculate timestamps relative to the start of the
conversation. First of all the timestamp of the first packet that has been
@ -3178,33 +3199,22 @@ SVN 23058 to see the implementation of conversation timestamps for
the tcp-dissector.
2.2.9 The example conversation code with GMemChunk's.
2.2.3 The example conversation code using se_alloc'd memory.
For a conversation between two IP addresses and ports you can use this as an
example. This example uses the GMemChunk to allocate memory and stores the data
example. This example uses se_alloc() to allocate memory and stores the data
pointer in the conversation 'data' variable.
NOTE: Remember to register the init routine (my_dissector_init) in the
protocol_register routine.
/************************ Global values ************************/
/* the number of entries in the memory chunk array */
#define my_init_count 10
/* define your structure here */
typedef struct {
} my_entry_t;
/* the GMemChunk base structure */
static GMemChunk *my_vals = NULL;
/* Registered protocol number */
static int my_proto = -1;
/********************* in the dissector routine *********************/
/* the local variables in the dissector */
@ -3225,7 +3235,7 @@ else {
/* new conversation create local data structure */
data_ptr = g_mem_chunk_alloc(my_vals);
data_ptr = se_alloc(sizeof(my_entry_t));
/*** add your code here to setup the new data structure ***/
@ -3238,38 +3248,12 @@ else {
/* at this point the conversation data is ready */
/******************* in the dissector init routine *******************/
#define my_init_count 20
static void
my_dissector_init(void)
{
/* destroy memory chunks if needed */
if (my_vals)
g_mem_chunk_destroy(my_vals);
/* now create memory chunks */
my_vals = g_mem_chunk_new("my_proto_vals",
sizeof(my_entry_t),
my_init_count * sizeof(my_entry_t),
G_ALLOC_AND_FREE);
}
/***************** in the protocol register routine *****************/
/* register re-init routine */
register_init_routine(&my_dissector_init);
my_proto = proto_register_protocol("My Protocol", "My Protocol", "my_proto");
2.2.10 An example conversation code that starts at a specific frame number.
2.2.4 An example conversation code that starts at a specific frame number.
Sometimes a dissector has determined that a new conversation is needed that
starts at a specific frame number, when a capture session encompasses multiple
@ -3293,7 +3277,7 @@ that starts at the specific frame number.
}
2.2.11 The example conversation code using conversation index field.
2.2.5 The example conversation code using conversation index field.
Sometimes the conversation isn't enough to define a unique data storage
value for the network traffic. For example if you are storing information
@ -3328,10 +3312,10 @@ upon the conversation index and values inside the request packets.
opcode = 0;
if (!request_val && !reply)
{
new_request_key = g_mem_chunk_alloc(afs_request_keys);
new_request_key = se_alloc(sizeof(struct afs_request_key));
*new_request_key = request_key;
request_val = g_mem_chunk_alloc(afs_request_vals);
request_val = se_alloc(sizeof(struct afs_request_val));
request_val -> opcode = pntohl(&afsh->opcode);
opcode = request_val->opcode;
@ -3394,7 +3378,7 @@ static void sub_dissector(tvbuff_t *tvb, packet_info *pinfo,
*/
conversation = find_conversation(pinfo->fd->num,
&pinfo->src, &pinfo->dst, protocol,
src_port, dst_port, new_conv_info, 0);
src_port, dst_port, 0);
/* If there is no such conversation, or if there is one but for
someone else's protocol then we just create a new conversation
@ -3402,7 +3386,7 @@ static void sub_dissector(tvbuff_t *tvb, packet_info *pinfo,
*/
if ( (conversation == NULL) ||
(conversation->dissector_handle != sub_dissector_handle) ) {
new_conv_info = g_mem_chunk_alloc(new_conv_vals);
new_conv_info = se_alloc(sizeof(struct _new_conv_info));
new_conv_info->data1 = value1;
/* create the conversation for the dynamic port */
@ -3476,7 +3460,7 @@ static dissector_handle_t sub_dissector_handle;
/* if conversation has a data field, create it and load structure */
new_conv_info = g_mem_chunk_alloc(new_conv_vals);
new_conv_info = se_alloc(sizeof(struct _new_conv_info));
new_conv_info->data1 = value1;
/* create the conversation for the dynamic server address and port */