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Add implementation of injecting tcp rst package

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This commit is contained in:
luwenpeng
2024-04-30 15:30:43 +08:00
parent dc37306594
commit 95e0982fd1
3 changed files with 248 additions and 1 deletions
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239
src/stellar/inject.cpp Normal file
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#include <time.h>
#include "tcp_utils.h"
#include "udp_utils.h"
#include "ipv4_utils.h"
#include "ipv6_utils.h"
#include "packet_io.h"
#include "packet_priv.h"
#include "session_priv.h"
#include "stellar_priv.h"
// OK
#define CHECKSUM_CARRY(x) (x = (x >> 16) + (x & 0xffff), (~(x + (x >> 16)) & 0xffff))
static inline int checksum(uint16_t *data, int len)
{
int sum = 0;
int nleft = len;
uint16_t ans = 0;
uint16_t *w = data;
while (nleft > 1)
{
sum += *w++;
nleft -= 2;
}
if (nleft == 1)
{
*(char *)(&ans) = *(char *)w;
sum += ans;
}
return sum;
}
// OK
static inline void calc_tcp_seq_and_ack(const struct session *sess, enum session_direction inj_dir, uint32_t *seq, uint32_t *ack)
{
/*
* +--------+ current packet +---------+ C2S RST +--------+
* | |----------------->| |----------------->| |
* | Client | | Stellar | | Server |
* | |<-----------------| |<-----------------| |
* +--------+ S2C RST +---------+ +--------+
*
* for example: current packet is C2S
*
* inject direction == current direction (inject C2S RST)
* seq = current_packet_seq
* ack = current_packet_ack
*
* inject direction != current direction (inject S2C RST)
* seq = s2c_direction_last_seq + s2c_direction_last_len
* ack = current_packet_seq
*/
enum session_direction curr_dir = session_get_current_direction(sess);
enum session_direction peer_dir = (curr_dir == SESSION_DIRECTION_C2S) ? SESSION_DIRECTION_S2C : SESSION_DIRECTION_C2S;
const struct tcp_half *tcp_curr_half = &sess->tcp_halfs[curr_dir];
const struct tcp_half *tcp_peer_half = &sess->tcp_halfs[peer_dir];
if (inj_dir == curr_dir)
{
*seq = tcp_curr_half->seq;
*ack = tcp_curr_half->ack;
}
else
{
*seq = tcp_peer_half->seq + tcp_peer_half->len;
*ack = tcp_curr_half->seq;
}
}
// OK
#define RANGE(rand, start, end) (start + rand % (end - start + 1)) // [start, end]
static inline void calc_ipid_ttl_win(uint16_t *ipid, uint8_t *ttl, uint16_t *win)
{
struct timespec curtime;
clock_gettime(CLOCK_THREAD_CPUTIME_ID, &curtime);
uint64_t random = (0x013579ABCDEF ^ (uint64_t)curtime.tv_nsec);
*ipid = (uint16_t)(RANGE(random, 32767, 65535));
*ttl = (uint8_t)(RANGE(random, 48, 120));
*win = (uint16_t)(RANGE(random, 1000, 1460));
}
// OK
static inline void update_ip6_hdr(struct ip6_hdr *ip6hdr, int trim)
{
uint16_t len = ipv6_hdr_get_payload_len(ip6hdr);
ipv6_hdr_set_payload_len(ip6hdr, len - trim);
}
// OK
static inline void update_ip4_hdr(struct ip *iphdr, uint16_t ipid, uint8_t ttl, int trim)
{
int hdr_len = ipv4_hdr_get_hdr_len(iphdr);
uint16_t total = ipv4_hdr_get_total_len(iphdr);
ipv4_hdr_set_total_len(iphdr, total - trim);
ipv4_hdr_set_ipid(iphdr, ipid);
ipv4_hdr_set_ttl(iphdr, ttl);
ipv4_hdr_set_checksum(iphdr, 0);
uint16_t sum = checksum((uint16_t *)iphdr, hdr_len);
sum = CHECKSUM_CARRY(sum);
ipv4_hdr_set_checksum(iphdr, ntohs(sum));
}
// OK
static inline void update_tcp_hdr(struct tcphdr *tcphdr, uint32_t seq, uint32_t ack, uint16_t win, uint8_t flags)
{
tcp_hdr_set_seq(tcphdr, seq);
tcp_hdr_set_ack(tcphdr, ack);
tcp_hdr_set_hdr_len(tcphdr, sizeof(struct tcphdr));
tcp_hdr_set_flags(tcphdr, flags);
tcp_hdr_set_window(tcphdr, win);
tcp_hdr_set_checksum(tcphdr, 0);
tcp_hdr_set_urg_ptr(tcphdr, 0);
uint16_t sum = checksum((uint16_t *)tcphdr, sizeof(struct tcphdr));
sum = CHECKSUM_CARRY(sum);
tcp_hdr_set_checksum(tcphdr, ntohs(sum));
}
// OK
static inline void update_udp_hdr(struct udphdr *udphdr, uint16_t trim)
{
uint16_t total = udp_hdr_get_total_len(udphdr);
udp_hdr_set_total_len(udphdr, total - trim);
udp_hdr_set_checksum(udphdr, 0);
uint16_t sum = checksum((uint16_t *)udphdr, total - trim);
sum = CHECKSUM_CARRY(sum);
udp_hdr_set_checksum(udphdr, ntohs(sum));
}
/******************************************************************************
* Public API
******************************************************************************/
// return 0: success, -1: failed
int stellar_inject_icmp_unreach(const struct session *sess, enum session_direction inj_dir, uint16_t thr_idx)
{
// TODO
return -1;
}
// OK
int stellar_inject_tcp_rst(const struct session *sess, enum session_direction inj_dir, uint16_t thr_idx)
{
if (session_get_type(sess) != SESSION_TYPE_TCP)
{
session_inc_stat((struct session *)sess, inj_dir, STAT_INJ_PKTS_FAIL, 1);
return -1;
}
const struct packet *pkt = session_get_1st_packet(sess, inj_dir);
if (pkt == NULL)
{
session_inc_stat((struct session *)sess, inj_dir, STAT_INJ_PKTS_FAIL, 1);
return -1;
}
uint8_t ttl = 0;
uint16_t win = 0;
uint16_t ipid = 0;
uint32_t seq = 0;
uint32_t ack = 0;
int trim = 0;
char buff[4096] = {0};
struct ip *iphdr;
struct ip6_hdr *ip6hdr;
struct tcphdr *tcphdr;
struct packet_layer *layer;
int len = packet_get_len(pkt);
int8_t layers = packet_get_layers(pkt);
memcpy(buff, packet_get_data(pkt), len);
calc_tcp_seq_and_ack(sess, inj_dir, &seq, &ack);
calc_ipid_ttl_win(&ipid, &ttl, &win);
for (int8_t i = layers - 1; i >= 0; i--)
{
layer = (struct packet_layer *)packet_get_layer(pkt, i);
switch (layer->type)
{
case LAYER_TYPE_TCP:
trim = layer->hdr_len + layer->pld_len - sizeof(struct tcphdr);
tcphdr = (struct tcphdr *)(buff + layer->hdr_offset);
update_tcp_hdr(tcphdr, seq, ack, win, TH_RST | TH_ACK);
break;
case LAYER_TYPE_IPV4:
iphdr = (struct ip *)(buff + layer->hdr_offset);
update_ip4_hdr(iphdr, ipid, ttl, trim);
break;
case LAYER_TYPE_IPV6:
ip6hdr = (struct ip6_hdr *)(buff + layer->hdr_offset);
update_ip6_hdr(ip6hdr, trim);
break;
default:
break;
}
}
struct packet inj_pkt;
packet_parse(&inj_pkt, buff, len - trim);
if (packet_io_inject(runtime->packet_io, thr_idx, &inj_pkt, 1) == 1)
{
session_inc_stat((struct session *)sess, inj_dir, STAT_INJ_PKTS_SUSS, 1);
session_inc_stat((struct session *)sess, inj_dir, STAT_INJ_BYTES_SUSS, len - trim);
return 0;
}
else
{
session_inc_stat((struct session *)sess, inj_dir, STAT_INJ_PKTS_FAIL, 1);
return -1;
}
}
int stellar_inject_tcp_payload(const struct session *sess, enum session_direction inj_dir, uint16_t thr_idx, const char *payload, uint16_t len)
{
// TODO
return -1;
}
int stellar_inject_udp_payload(const struct session *sess, enum session_direction inj_dir, uint16_t thr_idx, const char *payload, uint16_t len)
{
// TODO
return -1;
}
int stellar_inject_ctrl_msg(const struct session *sess, uint16_t *sids, int nr_sid, uint16_t thr_idx, const char *msg, uint16_t len)
{
// TODO
return -1;
}
int stellar_inject_stateless_pkt(uint16_t link_id, uint16_t thr_idx, const char *packet, uint16_t len)
{
// TODO
return -1;
}