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Handling of TCPv4 fragments

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With support for refragmenting too big fragments
This commit is contained in:
Michal Zima
2012-04-27 16:43:31 +02:00
parent 9ac06588a8
commit 754319efc2
3 changed files with 224 additions and 5 deletions
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94
src/nat.c
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@@ -41,8 +41,14 @@ struct s_radixtree_nat4 {
unsigned char zeros; /* unused space */
} __attribute__ ((__packed__));
struct s_radixtree_fragments4 {
struct s_ipv4_addr addr;
unsigned short id;
} __attribute__ ((__packed__));
radixtree_t *nat6_tcp, *nat6_udp, *nat6_icmp,
*nat4_tcp, *nat4_udp, *nat4_icmp;
*nat4_tcp, *nat4_udp, *nat4_icmp,
*nat4_tcp_fragments;
void nat_init(void)
{
@@ -53,6 +59,8 @@ void nat_init(void)
nat4_tcp = radixtree_create();
nat4_udp = radixtree_create();
nat4_icmp = radixtree_create();
nat4_tcp_fragments = radixtree_create();
}
void nat_quit(void)
@@ -66,6 +74,9 @@ void nat_quit(void)
radixtree_destroy(nat4_tcp, 12);
radixtree_destroy(nat4_udp, 12);
radixtree_destroy(nat4_icmp, 12);
/* 32 + 16 = 48 / 6 = 8 */
radixtree_destroy(nat4_tcp_fragments, 8);
}
struct s_nat *nat_out(radixtree_t *nat_proto6, radixtree_t *nat_proto4,
@@ -147,3 +158,84 @@ struct s_nat *nat_in(radixtree_t *nat_proto4, struct s_ipv4_addr ipv4_src,
return result;
}
}
/**
* Save and retrieve NATted connections via fragment identification.
*
* @param nat_proto4 Radix tree of fragments
* @param ipv4_src Source IPv4 address
* @param id Fragment identification
* @param nat Connection to save
*
* @return Connection
*/
struct s_nat *nat_in_fragments(radixtree_t *nat_proto4,
struct s_ipv4_addr ipv4_src,
unsigned short id, struct s_nat *nat)
{
struct s_nat *result;
/* create structure to search in the tree */
struct s_radixtree_fragments4 radixsearch4;
radixsearch4.addr = ipv4_src;
radixsearch4.id = id;
if ((result = (struct s_nat *) radixtree_lookup(nat_proto4,
radixtree_chunker, &radixsearch4, sizeof(radixsearch4))) == NULL) {
if (nat != NULL) {
/* when fragmentation is not found, add one */
radixtree_insert(nat_proto4, radixtree_chunker,
&radixsearch4, sizeof(radixsearch4),
nat);
return nat;
} else {
/* nothing found and nothing to be added */
return NULL;
}
} else {
if (nat != NULL) {
/* when fragmentation is found, is it the same? */
if (result == nat) {
/* OK, return */
return result;
} else {
/* sender determines usage of IDs, so this one
* shouldn't be used anymore for that
* connection */
radixtree_delete(nat_proto4, radixtree_chunker,
&radixsearch4,
sizeof(radixsearch4));
radixtree_insert(nat_proto4, radixtree_chunker,
&radixsearch4,
sizeof(radixsearch4), nat);
return nat;
}
} else {
/* refresh it's connection and return */
result->last_packet = time(NULL);
return result;
}
}
}
/**
* Remove one entry from "fragment NAT".
*
* @param nat_proto4 Radix tree of fragments
* @param ipv4_src Source IPv4 address
* @param id Fragment identification
*/
void nat_in_fragments_clenup(radixtree_t *nat_proto4,
struct s_ipv4_addr ipv4_src, unsigned short id)
{
/* create structure to search in the tree */
struct s_radixtree_fragments4 radixsearch4;
radixsearch4.addr = ipv4_src;
radixsearch4.id = id;
if (radixtree_lookup(nat_proto4, radixtree_chunker, &radixsearch4,
sizeof(radixsearch4)) != NULL) {
radixtree_delete(nat_proto4, radixtree_chunker, &radixsearch4,
sizeof(radixsearch4));
}
}