jeka
/
utun2
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
Browse Source

Fix UDP and ICMP packet construction at the TUN boundary

proxy
evgeny 3 days ago
parent
fdec5b65c5
commit
518df33b0e
4 changed files with 77 additions and 10 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 20
      src/proxy/icmp_proxy.c
  2. 5
      src/proxy/udp_proxy.c
  3. 4
      tests/Makefile.am
  4. 58
      tests/test_proxy_packets.c

20
src/proxy/icmp_proxy.c
Unescape View File

@ -53,6 +53,14 @@ struct icmp_proxy_ctx* g_icmp_ctx = NULL;
static void req_expire_timer_cb(void* arg);
static void req_expire(struct icmp_proxy_ctx* ctx);
static uint16_t icmp_checksum(const uint8_t* data, size_t len) {
uint32_t sum = 0;
while (len >= 2) { sum += ((uint16_t)data[0] << 8) | data[1]; data += 2; len -= 2; }
if (len) sum += (uint16_t)data[0] << 8;
while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16);
return htons((uint16_t)~sum);
}
static struct icmp_request* req_find_by_id(struct icmp_request* head, uint16_t echo_id, uint16_t echo_seq) {
struct icmp_request* r;
for (r = head; r; r = r->next) if (r->echo_id == echo_id && r->echo_seq == echo_seq) return r;
@ -76,10 +84,7 @@ static int exit_send_echo(struct UTUN_INSTANCE* inst, uint64_t client_node_id,
icmp_hdr->icmp_seq = echo_seq;
if (payload_len > 0) memcpy(icmp_hdr->icmp_data, payload, payload_len);
icmp_hdr->icmp_cksum = 0;
uint32_t sum = 0; uint16_t* w = (uint16_t*)icmp_hdr;
for (size_t i = 0; i < (icmp_len + 1) / 2; i++) sum += w[i];
while (sum >> 16) sum = (sum & 0xFFFF) + (sum >> 16);
icmp_hdr->icmp_cksum = ~(uint16_t)sum;
icmp_hdr->icmp_cksum = icmp_checksum((const uint8_t*)icmp_hdr, icmp_len);
DEBUG_INFO(DEBUG_CATEGORY_PROXY, "icmp_proxy: sendto dst=0x%08x id=0x%04x seq=%u len=%zu",
dst_ip, echo_id, echo_seq, icmp_len);
@ -260,6 +265,7 @@ int icmp_proxy_deliver_reply(struct UTUN_INSTANCE* inst,
}
struct tun_if* tun = inst->tcp_proxy_client->tun;
if (payload_len > 65506) { DEBUG_WARN(DEBUG_CATEGORY_PROXY, "icmp_proxy: payload too large len=%zu", payload_len); return -1; }
size_t icmp_len = ICMP_MINLEN + payload_len;
size_t pkt_len = 20 + icmp_len;
uint8_t* pkt = u_malloc(pkt_len);
@ -281,14 +287,12 @@ int icmp_proxy_deliver_reply(struct UTUN_INSTANCE* inst,
icmp_hdr->icmp_id = echo_id; icmp_hdr->icmp_seq = echo_seq;
if (payload_len > 0) memcpy(icmp_hdr->icmp_data, payload, payload_len);
icmp_hdr->icmp_cksum = 0;
uint32_t sum = 0; uint16_t* w = (uint16_t*)icmp_hdr;
for (size_t i = 0; i < (icmp_len + 1) / 2; i++) sum += w[i];
while (sum >> 16) sum = (sum & 0xFFFF) + (sum >> 16);
icmp_hdr->icmp_cksum = ~(uint16_t)sum;
icmp_hdr->icmp_cksum = icmp_checksum((const uint8_t*)icmp_hdr, icmp_len);
struct ll_entry* e = queue_entry_new(0);
if (!e) { u_free(pkt); return -1; }
e->dgram = u_malloc(1 + pkt_len);
if (!e->dgram) { DEBUG_ERROR(DEBUG_CATEGORY_PROXY, "icmp_proxy: reply allocation failed"); u_free(pkt); queue_entry_free(e); return -1; }
e->dgram[0] = 4; memcpy(e->dgram + 1, pkt, pkt_len); e->len = 1 + pkt_len;
u_free(pkt);
DEBUG_INFO(DEBUG_CATEGORY_PROXY, "icmp_proxy: reply delivered to TUN id=0x%04x seq=%u", echo_id, echo_seq);

5
src/proxy/udp_proxy.c
Unescape View File

@ -178,14 +178,14 @@ int udp_proxy_deliver_reply(struct UTUN_INSTANCE* inst,
uint32_t src_ip, uint16_t src_port,
uint32_t dst_ip, uint16_t dst_port,
const uint8_t* payload, size_t payload_len) {
if (!inst || !inst->tcp_proxy_client || !inst->tcp_proxy_client->tun) return -1;
if (!inst || !inst->tcp_proxy_client || !inst->tcp_proxy_client->tun || payload_len > 65506) return -1;
// Собрать IP/UDP ответный пакет
size_t ip_len = 20 + 8 + payload_len;
uint8_t* pkt = u_malloc(ip_len);
if (!pkt) return -1;
memset(pkt, 0, 20);
memset(pkt, 0, 28); // IPv4 UDP checksum=0: проверка отключена явно
pkt[0] = 0x45; pkt[8] = 64; pkt[9] = IPPROTO_UDP;
memcpy(pkt + 12, &src_ip, 4); memcpy(pkt + 16, &dst_ip, 4);
@ -205,6 +205,7 @@ int udp_proxy_deliver_reply(struct UTUN_INSTANCE* inst,
struct ll_entry* e = queue_entry_new(0);
if (!e) { u_free(pkt); return -1; }
e->dgram = u_malloc(1 + ip_len);
if (!e->dgram) { DEBUG_ERROR(DEBUG_CATEGORY_PROXY, "udp_proxy: reply allocation failed"); u_free(pkt); queue_entry_free(e); return -1; }
e->dgram[0] = 4; memcpy(e->dgram + 1, pkt, ip_len); e->len = 1 + ip_len;
u_free(pkt);
queue_data_put(inst->tcp_proxy_client->tun->input_queue, e);

4
tests/Makefile.am
Unescape View File

@ -632,3 +632,7 @@ test_etcp_router_tcp_LDADD = $(LIBUTUN) $(COMMON_LIBS)
test_services_SOURCES = test_services.c
test_services_CFLAGS = -I$(top_srcdir)/src -I$(top_srcdir)/src/routing_layer -I$(top_srcdir)/src/transport_layer -I$(top_srcdir)/lib
test_services_LDADD = $(LIBUTUN) $(CRYPTO_LIBS) $(COMMON_LIBS)
check_PROGRAMS += test_proxy_packets
test_proxy_packets_SOURCES = test_proxy_packets.c
test_proxy_packets_LDADD = $(LIBUTUN) $(CRYPTO_LIBS) $(COMMON_LIBS)

58
tests/test_proxy_packets.c
Unescape View File

@ -0,0 +1,58 @@
// Проверяем пакеты на границе proxy → TUN: длины, адреса, payload и checksum.
#include <stdio.h>
#include <string.h>
#include "utun_instance.h"
#include "tun_if.h"
#include "proxy/udp_proxy.h"
#include "proxy/icmp_proxy.h"
#include "debug_config.h"
#include "mem.h"
#define CHECK(x) do { if (!(x)) { fprintf(stderr, "FAIL line %d: %s\n", __LINE__, #x); return 1; } } while (0)
static unsigned checksum_sum(const uint8_t* p, size_t n) {
unsigned sum = 0;
while (n >= 2) { sum += ((unsigned)p[0] << 8) | p[1]; p += 2; n -= 2; }
if (n) sum += (unsigned)p[0] << 8;
while (sum >> 16) sum = (sum & 65535) + (sum >> 16);
return sum;
}
int main(void) {
debug_config_init(); debug_set_level(DEBUG_LEVEL_WARN);
struct UASYNC* ua = uasync_create();
struct UTUN_INSTANCE* inst = u_calloc(1, sizeof(*inst));
struct tcp_proxy_client client = {0};
struct tun_if tun = {0};
CHECK(ua && inst);
inst->tcp_proxy_client = &client; client.tun = &tun;
tun.input_queue = queue_new(ua, 0, 0, 0, "packet_test");
CHECK(tun.input_queue);
uint8_t payload[1501];
for (size_t i = 0; i < sizeof(payload); i++) payload[i] = (uint8_t)(i * 17 + 3);
const uint8_t src[4] = {192, 0, 2, 1}, dst[4] = {10, 0, 0, 2};
uint32_t src_ip, dst_ip; memcpy(&src_ip, src, 4); memcpy(&dst_ip, dst, 4);
for (size_t len = 0; len <= sizeof(payload); len++) {
CHECK(udp_proxy_deliver_reply(inst, src_ip, htons(53), dst_ip, htons(23456), payload, len) == 0);
struct ll_entry* e = queue_data_get(tun.input_queue);
CHECK(e && e->len == 29 + len);
const uint8_t* ip = e->dgram + 1;
CHECK(e->dgram[0] == 4 && ip[9] == 17 && checksum_sum(ip, 20) == 65535);
CHECK(memcmp(ip + 12, src, 4) == 0 && memcmp(ip + 16, dst, 4) == 0);
CHECK(ip[26] == 0 && ip[27] == 0);
CHECK(memcmp(ip + 28, payload, len) == 0);
queue_dgram_free(e); queue_entry_free(e);
CHECK(icmp_proxy_deliver_reply(inst, dst_ip, src_ip, htons(123), htons(5), payload, len) == 0);
e = queue_data_get(tun.input_queue);
CHECK(e && e->len == 29 + len);
ip = e->dgram + 1;
CHECK(ip[9] == 1 && checksum_sum(ip, 20) == 65535 && checksum_sum(ip + 20, 8 + len) == 65535);
CHECK(ip[20] == 0 && ip[24] == 0 && ip[25] == 123 && ip[27] == 5);
CHECK(memcmp(ip + 28, payload, len) == 0);
queue_dgram_free(e); queue_entry_free(e);
}
queue_free(tun.input_queue); u_free(inst); uasync_destroy(ua, 0);
CHECK(u_get_allocated_count() == 0);
puts("[PASS] proxy UDP/ICMP packets: payload lengths 0..1501");
return 0;
}
Write Preview
Loading…
Cancel
Save