Re: [Discussion] Retrieving a CID

[John Heffner <jheffner@xxxxxxx>]

On Oct 24, 2005, at 5:32 AM, Martin Röhricht wrote:

> Hello again,
>
> I'd like to get the corresponding CID for a connection of which I know 
> the
> local and the remote IP address as well as the remote port (the local 
> port is
> not known by default). So I thought of using the 		
> 	web100_connection_find(agent, spec);
> function to obtain the information. So I store the IP addresses in 
> char arrays
> 	const char LocalAddress[16] = "192.168.0.17";
> 	const char RemoteAddress[16] = "192.168.0.18";
> and try to convert them into a given spec like this:
> 	struct web100_connection_spec   *spec;
> 	spec = (struct web100_connection_spec*) malloc(sizeof(struct
> web100_connection_spec));
> 	[...]
> 	inet_aton(LocalAddress, &src_t);
>         spec->src_addr = ntohl(src_t.s_addr);
>         inet_aton(RemoteAddress, &dst_t);
>         spec->dst_addr = ntohl(dst_t.s_addr);
>         spec->src_port = LocalPort;
>         spec->dst_port = RemotePort;
>
> Unfortunately web100_connection_find returns a NULL pointer ...

web100_connection_find() only returns a single connection, not a list 
of connections, so it required a full match on the spec.  What you need 
to do is step through the list of all connections in a loop doing a 
match on just the parts of the spec you want.  See below for an 
example.  (You seem not to have a remote port, but I'm assuming you 
do.)

Incidentally, the equivalent python code is:

import Web100
agent = Web100.Web100Agent()
cl = agent.connection_match('192.168.0.17', None, '192.168.0.18', 
RemotePort)
cid = cl[0].cid

It works pretty well for this if you can use it. :-)

  -John


> Here is the small source code:
> --------------------------------8<---------------------------------
> #include <stdio.h>
> #include <stdlib.h>
> #include <netinet/in.h>
> #include <pthread.h>
> #include "web100.h"
> #include "web100-int.h"
>
> const unsigned int  LocalPort = 0;
> const char LocalAddress[16] = "192.168.0.17";
> const unsigned int  RemotePort = 0;
> const char RemoteAddress[16] = "192.168.0.18";
>
> int main(int argc, char *argv[]) {
>         web100_agent            *agent;
>         web100_group            *group;
>         web100_connection       *conn;
>         struct web100_connection_spec   *spec, *spec2;
>         int     cid = -1;
>         struct  in_addr src_t, dst_t;
>
>         spec = (struct web100_connection_spec*) malloc(sizeof(struct
> web100_connection_spec));
>
>         if((agent = web100_attach(WEB100_AGENT_TYPE_LOCAL, NULL)) == 
> NULL) {
>                 web100_perror("web100_attach");
>                 exit(EXIT_FAILURE);
>         }
>         group = web100_group_head(agent);
>         printf("group: %p, agent %p\n", group, agent);
>
>         inet_aton(LocalAddress, &src_t);
>         spec->src_addr = ntohl(src_t.s_addr);
>         inet_aton(RemoteAddress, &dst_t);
>         spec->dst_addr = ntohl(dst_t.s_addr);
>         spec->src_port = LocalPort;
>         spec->dst_port = RemotePort;
>
>         printf("spec: %p\n", spec);

conn = web100_connection_head(agent);
while (conn) {
	spec2 = web100_get_connection_spec(conn);
	if (spec->src_addr == spec2->src_addr && spec->dst_addr == 
spec2->dst_addr && spec->dst_port == spec2->dst_port)
		break;
}
if (conn == NULL) {
	printf("connection not found\n");
	return 1;
}

>         printf("conn: %p\n", conn);
>
>         cid = web100_get_connection_cid(conn);
>
>         return 0;
> }
> --------------------------------8<---------------------------------
>
> Has anyone an idea on what I am missing?
>
> Thanks,
> Martin
>
> _______________________________________________
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> http://internal.web100.org/mailman/listinfo/discussion


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