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test: add imitate_tcp_packet test case (TCP over GREv0: GRE enable checksum)

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This commit is contained in:
luwenpeng
2024-07-15 15:07:38 +08:00
parent d31cfd02fd
commit 07ce636f64
13 changed files with 408 additions and 150 deletions
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475
src/packet/packet_craft.cpp Normal file
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#include <time.h>
#include "log.h"
#include "checksum.h"
#include "tcp_utils.h"
#include "udp_utils.h"
#include "ip4_utils.h"
#include "ip6_utils.h"
#include "gtp_utils.h"
#include "gre_utils.h"
#include "packet_def.h"
#include "packet_utils.h"
#include "packet_layer.h"
#include "packet_parse.h"
#include "packet_craft.h"
#define PACKET_CRAFT_LOG_DEBUG(format, ...) LOG_DEBUG("packet craft", format, ##__VA_ARGS__)
#define PACKET_CRAFT_LOG_ERROR(format, ...) LOG_ERROR("packet craft", format, ##__VA_ARGS__)
struct fingerprint
{
// TODO
uint16_t ip_id;
uint8_t ip_ttl;
uint16_t tcp_win;
};
static uint8_t append_sender_fingerprint = 0;
/******************************************************************************
* Private API
******************************************************************************/
static inline void calc_packet_fingerprint(struct fingerprint *finger)
{
if (append_sender_fingerprint)
{
#define RANGE(rand, start, end) (start + rand % (end - start + 1)) // [start, end]
struct timespec time;
clock_gettime(CLOCK_MONOTONIC, &time);
uint64_t random = 0x013579ABCDEF ^ time.tv_nsec;
finger->ip_id = (uint16_t)(RANGE(random, 32767, 65535));
finger->ip_ttl = (uint8_t)(RANGE(random, 48, 120));
finger->tcp_win = (uint16_t)(RANGE(random, 1000, 1460));
}
else
{
finger->ip_id = 0;
finger->ip_ttl = 0;
finger->tcp_win = 0;
}
}
static void update_tcp_hdr(struct tcphdr *tcp, uint32_t seq, uint32_t ack, uint16_t win, uint8_t flags, uint16_t opts_len)
{
tcp_hdr_set_seq(tcp, seq);
tcp_hdr_set_ack(tcp, ack);
tcp_hdr_set_hdr_len(tcp, sizeof(struct tcphdr) + opts_len);
tcp_hdr_set_flags(tcp, flags);
if (win)
{
tcp_hdr_set_window(tcp, win);
}
tcp_hdr_set_urg_ptr(tcp, 0);
tcp_hdr_set_checksum(tcp, 0);
}
static void update_udp_hdr(struct udphdr *udp, int trim_len)
{
uint16_t total = udp_hdr_get_total_len(udp);
udp_hdr_set_total_len(udp, total - trim_len);
udp_hdr_set_checksum(udp, 0);
}
static void update_ip4_hdr(struct ip *ip, uint16_t ipid, uint8_t ttl, int trim_len)
{
int hdr_len = ip4_hdr_get_hdr_len(ip);
uint16_t total = ip4_hdr_get_total_len(ip);
ip4_hdr_set_total_len(ip, total - trim_len);
if (ipid)
{
ip4_hdr_set_ipid(ip, ipid);
}
if (ttl)
{
ip4_hdr_set_ttl(ip, ttl);
}
ip->ip_sum = 0;
ip->ip_sum = checksum((const void *)ip, hdr_len);
}
static void update_ip6_hdr(struct ip6_hdr *ip6, int trim_len)
{
uint16_t len = ip6_hdr_get_payload_len(ip6);
ip6_hdr_set_payload_len(ip6, len - trim_len);
}
static void update_gtp1_hdr(struct gtp1_hdr *gtp, int trim_len)
{
uint16_t msg_len = gtp1_hdr_get_msg_len(gtp);
gtp1_hdr_set_msg_len(gtp, msg_len - trim_len);
if (gtp1_hdr_get_seq_flag(gtp) && gtp1_hdr_get_seq(gtp))
{
PACKET_CRAFT_LOG_ERROR("crafted packets may be dropped by intermediate devices, the GTPv1 layer requires a sequence number");
}
}
static void update_gtp2_hdr(struct gtp2_hdr *gtp, int trim_len)
{
uint16_t msg_len = gtp2_hdr_get_msg_len(gtp);
gtp2_hdr_set_msg_len(gtp, msg_len - trim_len);
if (gtp2_hdr_get_seq(gtp))
{
PACKET_CRAFT_LOG_ERROR("crafted packets may be dropped by intermediate devices, the GTPv2 layer requires a sequence number");
}
}
static void update_gre1_hdr(struct gre1_hdr *gre, int trim_len)
{
uint16_t payload_len = gre1_hdr_get_payload_length(gre);
gre1_hdr_set_payload_length(gre, payload_len - trim_len);
}
static void update_packet_hdr(const struct packet *origin_pkt,
char *new_pkt_data, uint16_t new_pkt_len, int trim_len,
uint32_t tcp_seq, uint32_t tcp_ack, uint8_t tcp_flags, uint16_t tcp_opts_len)
{
uint8_t version = 0;
uint16_t sum = 0;
char *curr_hdr_ptr = NULL;
char *last_hdr_ptr = NULL;
struct tcphdr *tcp = NULL;
struct udphdr *udp = NULL;
struct ip *ip4 = NULL;
struct ip6_hdr *ip6 = NULL;
struct gtp1_hdr *gtp1 = NULL;
struct gtp2_hdr *gtp2 = NULL;
struct gre0_hdr *gre0 = NULL;
struct gre1_hdr *gre1 = NULL;
struct raw_layer *curr_layer = NULL;
struct raw_layer *last_layer = NULL;
struct fingerprint finger = {0};
calc_packet_fingerprint(&finger);
int count = packet_get_layer_count(origin_pkt);
for (int i = count - 1; i >= 0; i--)
{
curr_layer = (struct raw_layer *)packet_get_raw_layer(origin_pkt, i);
last_layer = (struct raw_layer *)packet_get_raw_layer(origin_pkt, i + 1);
curr_hdr_ptr = new_pkt_data + curr_layer->hdr_offset;
last_hdr_ptr = last_layer ? new_pkt_data + last_layer->hdr_offset : NULL;
switch (curr_layer->proto)
{
case LAYER_PROTO_TCP:
tcp = (struct tcphdr *)curr_hdr_ptr;
update_tcp_hdr(tcp, tcp_seq, tcp_ack, finger.tcp_win, tcp_flags, tcp_opts_len);
break;
case LAYER_PROTO_UDP:
udp = (struct udphdr *)curr_hdr_ptr;
update_udp_hdr(udp, trim_len);
break;
case LAYER_PROTO_IPV4:
ip4 = (struct ip *)curr_hdr_ptr;
if (last_layer && last_layer->proto == LAYER_PROTO_TCP)
{
tcp = (struct tcphdr *)last_hdr_ptr;
tcp->th_sum = checksum_v4(tcp, new_pkt_len - last_layer->hdr_offset, IPPROTO_TCP, &ip4->ip_src, &ip4->ip_dst);
}
if (last_layer && last_layer->proto == LAYER_PROTO_UDP)
{
udp = (struct udphdr *)last_hdr_ptr;
udp->uh_sum = checksum_v4(udp, new_pkt_len - last_layer->hdr_offset, IPPROTO_UDP, &ip4->ip_src, &ip4->ip_dst);
}
update_ip4_hdr(ip4, finger.ip_id, finger.ip_ttl, trim_len);
break;
case LAYER_PROTO_IPV6:
ip6 = (struct ip6_hdr *)curr_hdr_ptr;
if (last_layer && last_layer->proto == LAYER_PROTO_TCP)
{
tcp = (struct tcphdr *)last_hdr_ptr;
tcp->th_sum = checksum_v6(tcp, new_pkt_len - last_layer->hdr_offset, IPPROTO_TCP, &ip6->ip6_src, &ip6->ip6_dst);
}
if (last_layer && last_layer->proto == LAYER_PROTO_UDP)
{
udp = (struct udphdr *)last_hdr_ptr;
udp->uh_sum = checksum_v6(udp, new_pkt_len - last_layer->hdr_offset, IPPROTO_UDP, &ip6->ip6_src, &ip6->ip6_dst);
}
update_ip6_hdr(ip6, trim_len);
break;
case LAYER_PROTO_GTP_C: /* fall through */
case LAYER_PROTO_GTP_U:
version = peek_gtp_version(curr_hdr_ptr, curr_layer->hdr_len);
if (version == 1)
{
gtp1 = (struct gtp1_hdr *)curr_hdr_ptr;
update_gtp1_hdr(gtp1, trim_len);
}
if (version == 2)
{
gtp2 = (struct gtp2_hdr *)curr_hdr_ptr;
update_gtp2_hdr(gtp2, trim_len);
}
break;
case LAYER_PROTO_GRE:
version = peek_gre_version(curr_hdr_ptr, curr_layer->hdr_len);
if (version == 0)
{
gre0 = (struct gre0_hdr *)curr_hdr_ptr;
if (gre0_hdr_get_checksum_flag(gre0))
{
gre0_hdr_set_checksum(gre0, ntohs(0));
sum = checksum((const void *)curr_hdr_ptr, new_pkt_len - curr_layer->hdr_offset);
gre0_hdr_set_checksum(gre0, ntohs(sum));
}
}
if (version == 1)
{
gre1 = (struct gre1_hdr *)curr_hdr_ptr;
update_gre1_hdr(gre1, trim_len);
}
break;
default:
break;
}
}
}
/******************************************************************************
* Public API
******************************************************************************/
void append_sender_fingerprint_to_crafted_packet()
{
append_sender_fingerprint = 1;
}
/*
* tcp_seq: the sequence number of the new TCP packet (in host byte order)
* tcp_ack: the acknowledgment number of the new TCP packet (in host byte order)
* tcp_options_len: the length of the options (must be a multiple of 4)
*/
struct packet *craft_tcp_packet(const struct packet *origin_pkt, uint32_t tcp_seq, uint32_t tcp_ack, uint8_t tcp_flags,
const char *tcp_options, uint16_t tcp_options_len,
const char *tcp_payload, uint16_t tcp_payload_len)
{
// check arguments
if (origin_pkt == NULL ||
(tcp_options == NULL && tcp_options_len != 0) || (tcp_options != NULL && tcp_options_len == 0) ||
(tcp_payload == NULL && tcp_payload_len != 0) || (tcp_payload != NULL && tcp_payload_len == 0) ||
(tcp_options_len && tcp_options_len % 4 != 0))
{
PACKET_CRAFT_LOG_ERROR("craft TCP packet failed, invalid arguments");
return NULL;
}
// check the innermost layer of the original packet
int layers = packet_get_layer_count(origin_pkt);
const struct raw_layer *tcp_layer = packet_get_raw_layer(origin_pkt, layers - 1);
if (tcp_layer == NULL || tcp_layer->proto != LAYER_PROTO_TCP)
{
PACKET_CRAFT_LOG_ERROR("craft TCP packet failed, the innermost layer of the original packet is not TCP");
return NULL;
}
// calculate the new packet length
int trim_len = tcp_layer->hdr_len + tcp_layer->pld_len - tcp_options_len - tcp_payload_len - sizeof(struct tcphdr);
uint16_t new_pkt_len = origin_pkt->data_len - origin_pkt->trim_len - trim_len;
struct packet *new_pkt = packet_new(new_pkt_len);
if (new_pkt == NULL)
{
PACKET_CRAFT_LOG_ERROR("craft TCP packet failed, no space to allocate new packet");
return NULL;
}
// copy the data to the new packet
char *new_pkt_data = (char *)packet_get_raw_data(new_pkt);
memcpy(new_pkt_data, packet_get_raw_data(origin_pkt), tcp_layer->hdr_offset + sizeof(struct tcphdr));
if (tcp_options_len)
{
memcpy(new_pkt_data + tcp_layer->hdr_offset + sizeof(struct tcphdr), tcp_options, tcp_options_len);
}
memcpy(new_pkt_data + tcp_layer->hdr_offset + sizeof(struct tcphdr) + tcp_options_len, tcp_payload, tcp_payload_len);
// update the headers of the new packet
update_packet_hdr(origin_pkt, new_pkt_data, new_pkt_len, trim_len, tcp_seq, tcp_ack, tcp_flags, tcp_options_len);
packet_parse(new_pkt, new_pkt_data, new_pkt_len);
memcpy(&new_pkt->meta, &origin_pkt->meta, sizeof(struct metadata));
new_pkt->meta.origin_ctx = NULL;
return new_pkt;
}
struct packet *craft_udp_packet(const struct packet *origin_pkt, const char *udp_payload, uint16_t udp_payload_len)
{
// check arguments
if (origin_pkt == NULL || (udp_payload == NULL && udp_payload_len != 0) || (udp_payload != NULL && udp_payload_len == 0))
{
PACKET_CRAFT_LOG_ERROR("craft UDP packet failed, invalid arguments");
return NULL;
}
// check the innermost layer of the original packet
int layers = packet_get_layer_count(origin_pkt);
const struct raw_layer *udp_layer = packet_get_raw_layer(origin_pkt, layers - 1);
if (udp_layer == NULL || udp_layer->proto != LAYER_PROTO_UDP)
{
PACKET_CRAFT_LOG_ERROR("craft UDP packet failed, the innermost layer of the original packet is not UDP");
return NULL;
}
// calculate the new packet length
int trim_len = udp_layer->hdr_len + udp_layer->pld_len - udp_payload_len - sizeof(struct udphdr);
uint16_t new_pkt_len = origin_pkt->data_len - origin_pkt->trim_len - trim_len;
struct packet *new_pkt = packet_new(new_pkt_len);
if (new_pkt == NULL)
{
PACKET_CRAFT_LOG_ERROR("craft UDP packet failed, no space to allocate new packet");
return NULL;
}
// copy the data to the new packet
char *new_pkt_data = (char *)packet_get_raw_data(new_pkt);
memcpy(new_pkt_data, packet_get_raw_data(origin_pkt), udp_layer->hdr_offset + sizeof(struct udphdr));
memcpy(new_pkt_data + udp_layer->hdr_offset + sizeof(struct udphdr), udp_payload, udp_payload_len);
// update the headers of the new packet
update_packet_hdr(origin_pkt, new_pkt_data, new_pkt_len, trim_len, 0, 0, 0, 0);
packet_parse(new_pkt, new_pkt_data, new_pkt_len);
memcpy(&new_pkt->meta, &origin_pkt->meta, sizeof(struct metadata));
new_pkt->meta.origin_ctx = NULL;
return new_pkt;
}
struct packet *craft_packet_from_scratch(const struct layer layers[], uint16_t layer_count, const char *payload, uint16_t payload_len)
{
// check arguments
if (layers == NULL || layer_count == 0 || (payload == NULL && payload_len != 0) || (payload != NULL && payload_len == 0))
{
PACKET_CRAFT_LOG_ERROR("craft packet from scratch failed, invalid arguments");
return NULL;
}
// calculate the new packet length
uint16_t new_pkt_len = 0;
for (int i = 0; i < layer_count; i++)
{
if (layers[i].hdr.raw == NULL || layers[i].hdr_len == 0)
{
PACKET_CRAFT_LOG_ERROR("craft packet from scratch failed, the header of layer %d is invalid", i);
return NULL;
}
new_pkt_len += layers[i].hdr_len;
}
new_pkt_len += payload_len;
struct packet *new_pkt = packet_new(new_pkt_len);
if (new_pkt == NULL)
{
PACKET_CRAFT_LOG_ERROR("craft packet from scratch failed, no space to allocate new packet");
return NULL;
}
// copy the data to the new packet
char *new_pkt_data = (char *)packet_get_raw_data(new_pkt);
int offset = 0;
for (int i = 0; i < layer_count; i++)
{
memcpy(new_pkt_data + offset, layers[i].hdr.raw, layers[i].hdr_len);
offset += layers[i].hdr_len;
}
memcpy(new_pkt_data + offset, payload, payload_len);
// update the headers of the new packet
uint8_t version = 0;
uint16_t curr_hdr_len = 0;
char *curr_hdr_ptr = NULL;
struct tcphdr *tcp = NULL;
struct udphdr *udp = NULL;
struct ip *ip4 = NULL;
struct ip6_hdr *ip6 = NULL;
struct gtp1_hdr *gtp1 = NULL;
struct gtp2_hdr *gtp2 = NULL;
// update checksums and lengths
uint16_t curr_payload_len = payload_len;
for (int i = layer_count - 1; i >= 0; i--)
{
curr_hdr_len = layers[i].hdr_len;
curr_hdr_ptr = new_pkt_data + new_pkt_len - curr_hdr_len - curr_payload_len;
switch (layers[i].proto)
{
case LAYER_PROTO_TCP:
tcp = (struct tcphdr *)curr_hdr_ptr;
// update the TCP header
tcp_hdr_set_hdr_len(tcp, curr_hdr_len);
tcp_hdr_set_checksum(tcp, 0);
curr_payload_len += curr_hdr_len;
break;
case LAYER_PROTO_UDP:
udp = (struct udphdr *)curr_hdr_ptr;
// update the UDP header
udp_hdr_set_total_len(udp, curr_hdr_len + curr_payload_len);
udp_hdr_set_checksum(udp, 0);
curr_payload_len += curr_hdr_len;
break;
case LAYER_PROTO_IPV4:
ip4 = (struct ip *)curr_hdr_ptr;
// update the checksums of the upper layer
if (i + 1 < layer_count && layers[i + 1].proto == LAYER_PROTO_TCP)
{
tcp = (struct tcphdr *)(new_pkt_data + new_pkt_len - curr_payload_len);
tcp->th_sum = checksum_v4(tcp, curr_payload_len, IPPROTO_TCP, &ip4->ip_src, &ip4->ip_dst);
}
if (i + 1 < layer_count && layers[i + 1].proto == LAYER_PROTO_UDP)
{
udp = (struct udphdr *)(new_pkt_data + new_pkt_len - curr_payload_len);
udp->uh_sum = checksum_v4(udp, curr_payload_len, IPPROTO_UDP, &ip4->ip_src, &ip4->ip_dst);
}
// update the IPv4 header
ip4_hdr_set_hdr_len(ip4, curr_hdr_len);
ip4_hdr_set_total_len(ip4, curr_hdr_len + curr_payload_len);
ip4->ip_sum = 0;
ip4->ip_sum = checksum((const void *)ip4, curr_hdr_len);
curr_payload_len += curr_hdr_len;
break;
case LAYER_PROTO_IPV6:
ip6 = (struct ip6_hdr *)curr_hdr_ptr;
// update the checksums of the upper layer
if (i + 1 < layer_count && layers[i + 1].proto == LAYER_PROTO_TCP)
{
tcp = (struct tcphdr *)(new_pkt_data + new_pkt_len - curr_payload_len);
tcp->th_sum = checksum_v6(tcp, curr_payload_len, IPPROTO_TCP, &ip6->ip6_src, &ip6->ip6_dst);
}
if (i + 1 < layer_count && layers[i + 1].proto == LAYER_PROTO_UDP)
{
udp = (struct udphdr *)(new_pkt_data + new_pkt_len - curr_payload_len);
udp->uh_sum = checksum_v6(udp, curr_payload_len, IPPROTO_UDP, &ip6->ip6_src, &ip6->ip6_dst);
}
// update the IPv6 header
ip6_hdr_set_payload_len(ip6, curr_hdr_len + curr_payload_len - sizeof(struct ip6_hdr));
curr_payload_len += curr_hdr_len;
break;
case LAYER_PROTO_GTP_C: /* fall through */
case LAYER_PROTO_GTP_U:
version = peek_gtp_version(curr_hdr_ptr, curr_hdr_len);
if (version == 1)
{
gtp1 = (struct gtp1_hdr *)curr_hdr_ptr;
// update the GTP header
gtp1_hdr_set_msg_len(gtp1, curr_hdr_len + curr_payload_len - sizeof(struct gtp1_hdr));
}
if (version == 2)
{
gtp2 = (struct gtp2_hdr *)curr_hdr_ptr;
// update the GTP header
gtp2_hdr_set_msg_len(gtp2, curr_hdr_len + curr_payload_len - 4);
}
curr_payload_len += curr_hdr_len;
break;
case LAYER_PROTO_GRE:
// TODO
curr_payload_len += curr_hdr_len;
break;
default:
curr_payload_len += curr_hdr_len;
break;
}
}
packet_parse(new_pkt, new_pkt_data, new_pkt_len);
// no metadata for the new packet from scratch
new_pkt->meta.origin_ctx = NULL;
return new_pkt;
}