[dpdk-users] Sequence Number

[Konstantinos Schoinas <ece8537@upnet.gr>]

-------- Αρχικό μήνυμα --------
Θέμα: Sequence Number
Ημερομηνία: 2018-08-15 12:21
Αποστολέας: Konstantinos Schoinas <ece8537@upnet.gr>
Παραλήπτης: users <users-bounces@dpdk.org>

Hello,

I am building an application blocks TLS session if i find a sepcific 
forbidden Server Name Indication.
According to RFC i must make a response with Fatal Error (2) 
unrecognized name(112).

When i receive the Client Hello and after i Extract the SNI and check it 
against a black list i do process the client hello in order to response 
to client and terminate the session.

Although i am getting a lot of retransmit packets on wireshark so i 
suppose i am doing something wrong.

I think i mights have seq and ack number wrong or something.If anyone 
could help i would appreciate.
Here is the process of the packet after i check for the forbidden SNI:

uint32_t client_receive_ack = ntohl(th-⁠>recv_ack);
uint32_t client_send_seq = ntohl(th-⁠>sent_seq);

th-⁠>sent_seq = th-⁠>recv_ack;
th-⁠>recv_ack = htonl(client_send_seq + ntohs(iphdr-⁠>total_length));


uint16_t l = ntohs(ssl-⁠>length)-⁠0x02;
uint16_t ip_l = ntohs(iphdr-⁠>total_length) -⁠ l;

rte_pktmbuf_trim(m,l);
iphdr-⁠>total_length = htons(ip_l);
ssl-⁠>length = htons(2);

alert = (struct Alert *)((uint8_t *)ssl + 5);


iphdr-⁠>src_addr = dst_ip;
iphdr-⁠>dst_addr = src_ip;
th-⁠>src_port = dst_port;
th-⁠>dst_port = src_port;
ssl-⁠>type = 21; //alert message
alert-⁠>type = 2; // fatal error
alert-⁠>description = 112; // Unrecognized name

iphdr-⁠>hdr_checksum = 0;
th-⁠>cksum = 0;
iphdr-⁠>hdr_checksum = rte_ipv4_cksum(iphdr);

th-⁠>cksum = rte_ipv4_udptcp_cksum(iphdr,th);




Thanks for your time
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Subject: [dpdk-users] mempool metadata stored in private data section
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Hi,

I'm using rte_mempool_create_empty (followed by
rte_mempool_populate_default) to create a pool of buffers that have to
be used by the application, along with the buffers I need to have a
small set of meta information, so that when the user request an objects
(rte_mempool_get) it gets back the buffer + the meta data.

>From the documentation it seems that I could use the "private_data_size"
field while creating the pool, but the description is not very clear to
me: "The size of the private data appended after the mempool structure.
This is useful for storing some private data after the mempool
structure, as is done for rte_mbuf_pool for example."

Are those private data stored after each mempool object? It's legal then
do something like this: ((char*)buf_ptr + elt_size) to access the
private section of the buffer? (Assuming buf_ptr is the pointer returned
by rte_mempool_get, void*.).

>From the code in rte_mempool.c I see that:

.
 /*<
 * reserve a memory zone for this mempool: private data is<
 * cache-aligned<
 */<
 data_size = (private_data_size +<
 MEMPOOL_ALIGN_MASK) & (~RTE_MEMPOOL_ALIGN_MASK);
.

so it looks like that chunk of private data is just a big common buffer
allocated along with the whole mempool, the objects within the pool do
not have any private data by themselves.

How can I add some private data to each object of the mempool? (I know
the simpler solution would be to increase elt_size to cover the
requirement of the meta data I want to add, but what's the purpose of
private_data then??)

Thanks

-- 
BR, Filip
+48 666 369 823