Dynamic fake

desync.c

@@ -95,14 +95,26 @@ static bool sock_has_notsent(int sfd)
     }
     return tcpi.tcpi_notsent_bytes != 0;
 }
+
+
+static char *alloc_pktd(size_t n)
+{
+    char *p = mmap(0, n, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+    return p == MAP_FAILED ? 0 : p;
+}
+#define free_pktd(p, n) munmap(p, n)
 #else
 #define sock_has_notsent(sfd) 0
+
+#define alloc_pktd(n) malloc(n)
+#define free_pktd(p, n) free(p)
 #endif
 
-static struct packet get_tcp_fake(const char *buffer, size_t n,
+
+static struct packet get_tcp_fake(const char *buffer, ssize_t n,
         struct proto_info *info, const struct desync_params *opt)
 {
-    struct packet pkt;
+    struct packet pkt = { 0 };
     if (opt->fake_data.data) {
         pkt = opt->fake_data;
     }
@@ -113,12 +125,50 @@ static struct packet get_tcp_fake(const char *buffer, size_t n,
         }
         pkt = info->type == IS_HTTP ? fake_http : fake_tls;
     }
-    if (opt->fake_offset) {
-        if (pkt.size > opt->fake_offset) { 
-            pkt.size -= opt->fake_offset;
-            pkt.data += opt->fake_offset;
+    if (info->type != IS_HTTP 
+            && (opt->fake_mod || opt->fake_sni_count)) do {
+        ssize_t ps = n > pkt.size ? n : pkt.size;
+        char *p = alloc_pktd(ps);
+        if (!p) {
+            uniperror("malloc/mmap");
+            break;
+        }
+        const char *sni = 0;
+        if (opt->fake_sni_count) {
+            sni = opt->fake_sni_list[rand() % opt->fake_sni_count];
+        }
+        do {
+            if ((opt->fake_mod & FM_ORIG) && info->type == IS_HTTPS) {
+                memcpy(p, buffer, n);
+                
+                if (!sni || !change_tls_sni(sni, p, n, n)) {
+                    break;
+                }
+                LOG(LOG_E, "change sni error\n");
+            }
+            memcpy(p, pkt.data, pkt.size);
+            if (sni && change_tls_sni(sni, p, pkt.size, n) < 0) {
+                free_pktd(p, ps);
+                p = 0;
+                break;
+            }
+        } while(0);
+        if (p) {
+            if (opt->fake_mod & FM_RAND) {
+                randomize_tls(p, ps);
+            }
+            pkt.data = p;
+            pkt.size = ps;
+            pkt.dynamic = 1;
+        }
+    } while (0);
+    
+    if (opt->fake_offset.m) {
+        pkt.off = gen_offset(opt->fake_offset.pos, 
+            opt->fake_offset.flag, buffer, n, 0, info);
+        if (pkt.off > pkt.size || pkt.off < 0) {
+            pkt.off = 0;
         }
-        else pkt.size = 0;
     }
     return pkt;
 }
@@ -155,24 +205,30 @@ static ssize_t send_fake(int sfd, const char *buffer,
         return -1;
     }
     char *p = 0;
+    size_t ms = pos > pkt.size ? pos : pkt.size;
     ssize_t ret = -1;
     
     while (1) {
-        p = mmap(0, pos, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
-        if (p == MAP_FAILED) {
-            uniperror("mmap");
-            p = 0;
-            break;
+        if (pkt.dynamic) {
+            p = pkt.data;
+        }
+        else {
+            p = mmap(0, ms, 
+                PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+            if (p == MAP_FAILED) {
+                uniperror("mmap");
+                p = 0;
+                break;
+            }
+            memcpy(p, pkt.data, pkt.size);
         }
-        memcpy(p, pkt.data, pkt.size < pos ? pkt.size : pos);
-        
         if (setttl(sfd, opt->ttl ? opt->ttl : DEFAULT_TTL) < 0) {
             break;
         }
         if (opt->md5sig && set_md5sig(sfd, 5)) {
             break;
         }
-        struct iovec vec = { .iov_base = p, .iov_len = pos };
+        struct iovec vec = { .iov_base = p + pkt.off, .iov_len = pos };
         
         ssize_t len = vmsplice(fds[1], &vec, 1, SPLICE_F_GIFT);
         if (len < 0) {
@@ -184,7 +240,7 @@ static ssize_t send_fake(int sfd, const char *buffer,
             uniperror("splice");
             break;
         }
-        memcpy(p, buffer, pos);
+        memcpy(p + pkt.off, buffer, pos);
         
         if (setttl(sfd, params.def_ttl) < 0) {
             break;
@@ -195,7 +251,9 @@ static ssize_t send_fake(int sfd, const char *buffer,
         ret = len;
         break;
     }
-    if (p) munmap(p, pos);
+    if (!pkt.dynamic && p) {
+        munmap(p, ms);
+    }
     close(fds[0]);
     close(fds[1]);
     return ret;
@@ -273,15 +331,15 @@ static ssize_t send_fake(int sfd, const char *buffer,
         return -1;
     }
     s->tfile = hfile;
-    ssize_t len = -1;
+    ssize_t len = -1, ps = pkt.size - pkt.off;
     
     while (1) {
         DWORD wrtcnt = 0;
-        if (!WriteFile(hfile, pkt.data, pkt.size < pos ? pkt.size : pos, &wrtcnt, 0)) {
+        if (!WriteFile(hfile, pkt.data + pkt.off, ps < pos ? ps : pos, &wrtcnt, 0)) {
             uniperror("WriteFile");
             break;
         }
-        if (pkt.size < pos) {
+        if (ps < pos) {
             if (SetFilePointer(hfile, pos, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER) {
                 uniperror("SetFilePointer");
                 break;
@@ -562,9 +620,14 @@ ssize_t desync(struct poolhd *pool,
         }
         else switch (part.m) {
             #ifdef FAKE_SUPPORT
-            case DESYNC_FAKE:
+            case DESYNC_FAKE:;
+                struct packet pkt = get_tcp_fake(buffer, n, &info, &dp);
+                
                 if (pos != lp) s = send_fake(sfd, 
-                    buffer + lp, pos - lp, &dp, get_tcp_fake(buffer, n, &info, &dp));
+                    buffer + lp, pos - lp, &dp, pkt);
+                    
+                if (pkt.dynamic)
+                    free_pktd(pkt.data, pkt.size);
                 break;
             #endif
             case DESYNC_DISORDER:
@@ -680,10 +743,10 @@ ssize_t desync_udp(int sfd, char *buffer,
         else {
             pkt = fake_udp;
         }
-        if (dp->fake_offset) {
-            if (pkt.size > dp->fake_offset) { 
-                pkt.size -= dp->fake_offset;
-                pkt.data += dp->fake_offset;
+        if (dp->fake_offset.m) {
+            if (pkt.size > dp->fake_offset.pos) { 
+                pkt.size -= dp->fake_offset.pos;
+                pkt.data += dp->fake_offset.pos;
             }
             else pkt.size = 0;
         }

desync.h

@@ -26,4 +26,7 @@ struct proto_info {
     char init, type;
     int host_len, host_pos;
 };
+
+static long gen_offset(long pos, int flag,
+        const char *buffer, size_t n, long lp, struct proto_info *info);
 #endif

main.c

@@ -32,13 +32,13 @@ ASSERT(sizeof(struct in6_addr) == 16)
 
 
 struct packet fake_tls = { 
-    sizeof(tls_data), tls_data 
+    sizeof(tls_data), tls_data, 0, 0
 },
 fake_http = { 
-    sizeof(http_data), http_data
+    sizeof(http_data), http_data, 0, 0
 },
 fake_udp = { 
-    sizeof(udp_data), udp_data
+    sizeof(udp_data), udp_data, 0, 0
 };
 
 
@@ -106,11 +106,13 @@ static const char help_text[] = {
     #ifdef __linux__
     "    -S, --md5sig              Add MD5 Signature option for fake packets\n"
     #endif
-    "    -n, --tls-sni <str>       Change SNI in fake ClientHello\n"
+    "    -n, --fake-sni <str>      Change SNI in fake\n"
+    "                              Replaced: ? - rand let, # - rand num, * - rand let/num\n"
     #endif
     "    -t, --ttl <num>           TTL of fake packets, default 8\n"
-    "    -O, --fake-offset <n>     Fake data start offset\n"
+    "    -O, --fake-offset <pos_t> Fake data start offset\n"
     "    -l, --fake-data <f|:str>  Set custom fake packet\n"
+    "    -Q, --fake-tls-mod <r,o>  Modify fake TLS CH: rand,orig\n"
     "    -e, --oob-data <char>     Set custom OOB data\n"
     "    -M, --mod-http <h,d,r>    Modify HTTP: hcsmix,dcsmix,rmspace\n"
     "    -r, --tlsrec <pos_t>      Make TLS record at position\n"
@@ -164,11 +166,12 @@ const struct option options[] = {
     #ifdef __linux__
     {"md5sig",        0, 0, 'S'},
     #endif
-    {"tls-sni",       1, 0, 'n'},
+    {"fake-sni",      1, 0, 'n'},
     #endif
     {"ttl",           1, 0, 't'},
     {"fake-data",     1, 0, 'l'},
     {"fake-offset",   1, 0, 'O'},
+    {"fake-tls-mod",  1, 0, 'Q'},
     {"oob-data",      1, 0, 'e'},
     {"mod-http",      1, 0, 'M'},
     {"tlsrec",        1, 0, 'r'},
@@ -602,6 +605,10 @@ void clear_params(void)
                 mem_destroy(s.ipset);
                 s.hosts = 0;
             }
+            if (s.fake_sni_list != 0) {
+                free(s.fake_sni_list);
+                s.fake_sni_list = 0;
+            }
         }
         free(params.dp);
         params.dp = 0;
@@ -916,20 +923,39 @@ int main(int argc, char **argv)
             break;
             
         case 'O':
-            val = strtol(optarg, &end, 0);
-            if (val <= 0 || *end) 
+            if (parse_offset(&dp->fake_offset, optarg)) {
                 invalid = 1;
-            else
-                dp->fake_offset = val;
+                break;
+            } else dp->fake_offset.m = 1;
             break;
             
-        case 'n':
-            if (change_tls_sni(optarg, fake_tls.data, fake_tls.size)) {
-                fprintf(stderr, "error chsni\n");
-                clear_params();
-                return -1;
+        case 'Q':
+            end = optarg;
+            while (end && !invalid) {
+                switch (*end) {
+                    case 'r': 
+                        dp->fake_mod |= FM_RAND;
+                        break;
+                    case 'o': 
+                        dp->fake_mod |= FM_ORIG;
+                        break;
+                    default:
+                        invalid = 1;
+                        continue;
+                }
+                end = strchr(end, ',');
+                if (end) end++;
             }
-            printf("sni: %s\n", optarg);
+            break;
+            
+        case 'n':;
+            const char **p = add((void *)&dp->fake_sni_list,
+                    &dp->fake_sni_count, sizeof(optarg));
+            if (!p) {
+                invalid = 1;
+                continue;
+            }
+            *p = optarg;
             break;
             
         case 'l':

packets.c

@@ -102,7 +102,7 @@ static size_t find_tls_ext_offset(uint16_t type,
 }
 
 
-static size_t chello_ext_offset(uint16_t type, const char *data, size_t size)
+static size_t find_ext_block(const char *data, size_t size)
 {
     if (size < 44) {
         return 0;
@@ -114,43 +114,184 @@ static size_t chello_ext_offset(uint16_t type, const char *data, size_t size)
     uint16_t cip_len = ANTOHS(data, 44 + sid_len);
 
     size_t skip = 44 + sid_len + 2 + cip_len + 2;
-    return find_tls_ext_offset(type, data, size, skip);
+    return skip > size ? 0 : skip;
 }
 
 
-int change_tls_sni(const char *host, char *buffer, size_t bsize)
+static int merge_tls_records(char *buffer, ssize_t n)
 {
-    size_t sni_offs, pad_offs;
+    if (n < 5) {
+        return 0;
+    }
+    uint16_t full_sz = 0;
+    uint16_t r_sz = ANTOHS(buffer, 3);
+    int i = 0;
     
-    if (!(sni_offs = chello_ext_offset(0x00, buffer, bsize))) {
+    while (1) {
+        full_sz += r_sz;
+        if (5 + full_sz > n - 5
+                || buffer[5 + full_sz] != *buffer) {
+            break;
+        }
+        r_sz = ANTOHS(buffer, 5 + full_sz + 3);
+        
+        if (full_sz + 10 + r_sz > n) {
+            break;
+        }
+        memmove(buffer + 5 + full_sz, 
+            buffer + 10 + full_sz, n - (10 + full_sz));
+        i++;
+    }
+    SHTONA(buffer, 3, full_sz);
+    SHTONA(buffer, 7, full_sz - 4);
+    return i * 5;
+}
+
+
+static void copy_name(char *out, const char *name, size_t out_len)
+{
+    for (size_t i = 0; i < out_len; i++) {
+        switch (name[i]) {
+        case '*':;
+            int r = rand() % (10 + 'z' - 'a' + 1);
+            out[i] = (r < 10 ? '0' : ('a' - 10)) + r;
+            break;
+        case '?':
+            out[i] = 'a' + (rand() % ('z' - 'a' + 1));
+            break;
+        case '#':
+            out[i] = '0' + (rand() % 10);
+            break;
+        default:
+            out[i] = name[i];
+        }
+    }
+}
+
+
+static int remove_tls_ext(char *buffer, 
+        ssize_t n, size_t skip, uint16_t type)
+{
+    ssize_t ext_offs = find_tls_ext_offset(type, buffer, n, skip);
+    if (!ext_offs) {
+        return 0;
+    }
+    uint16_t ext_sz = ANTOHS(buffer, ext_offs + 2);
+    ssize_t ext_end = ext_offs + 4 + ext_sz;
+    if (ext_end > n) {
+        return 0;
+    }
+    memmove(buffer + ext_offs, buffer + ext_end, n - ext_end);
+    return ext_sz + 4;
+}
+
+
+static int resize_ech_ext(char *buffer, 
+        ssize_t n, size_t skip, int inc)
+{
+    ssize_t ech_offs = find_tls_ext_offset(0xfe0d, buffer, n, skip);
+    if (!ech_offs) {
+        return 0;
+    }
+    uint16_t ech_sz = ANTOHS(buffer, ech_offs + 2);
+    ssize_t ech_end = ech_offs + 4 + ech_sz;
+    
+    if (ech_sz < 12 || ech_end > n) {
+        return 0;
+    }
+    uint16_t enc_sz = ANTOHS(buffer, ech_offs + 4 + 6);
+    ssize_t pay_offs = ech_offs + 4 + 8 + enc_sz;
+    uint16_t pay_sz = ech_sz - (8 + enc_sz + 2);
+    
+    if (pay_offs + 2 > n || pay_sz < -inc) {
+        return 0;
+    }
+    SHTONA(buffer, ech_offs + 2, ech_sz + inc);
+    SHTONA(buffer, pay_offs, pay_sz + inc);
+    
+    memmove(buffer + ech_end + inc, buffer + ech_end, n - ech_end);
+    return inc;
+}
+
+
+static void resize_sni(char *buffer, ssize_t n,
+        ssize_t sni_offs, ssize_t sni_sz, ssize_t new_sz)
+{
+    SHTONA(buffer, sni_offs + 2, new_sz + 5);
+    SHTONA(buffer, sni_offs + 4, new_sz + 3);
+    SHTONA(buffer, sni_offs + 7, new_sz);
+    
+    ssize_t sni_end = sni_offs + 4 + sni_sz;
+    memmove(buffer + sni_end + new_sz - (sni_sz - 5), buffer + sni_end, n - sni_end);
+}
+
+
+int change_tls_sni(const char *host, char *buffer, ssize_t n, ssize_t nn)
+{
+    int avail = merge_tls_records(buffer, n);
+    avail += (nn - n);
+    
+    uint16_t r_sz = ANTOHS(buffer, 3);
+    r_sz += avail;
+    
+    size_t skip = find_ext_block(buffer, n);
+    if (!skip) {
         return -1;
     }
-    if (!(pad_offs = chello_ext_offset(0x15, buffer, bsize))) {
+    ssize_t sni_offs = find_tls_ext_offset(0x00, buffer, n, skip);
+    if (!sni_offs) {
         return -1;
     }
-    char *sni = &buffer[sni_offs];
-    char *pad = &buffer[pad_offs];
-    
-    uint16_t old_sz = ANTOHS(buffer, sni_offs + 2) - 5;
-    uint16_t free_sz = ANTOHS(buffer, pad_offs + 2);
     uint16_t new_sz = strlen(host);
+    uint16_t sni_sz = ANTOHS(buffer, sni_offs + 2);
     
-    ssize_t diff = new_sz - old_sz;
-  
-    if ((free_sz != (bsize - pad_offs - 4)) 
-            || free_sz < diff) {
+    if (sni_offs + 4 + sni_sz > n) {
         return -1;
     }
-    SHTONA(sni, 2, old_sz + diff + 5);
-    SHTONA(sni, 4, old_sz + diff + 3);
-    SHTONA(sni, 7, old_sz + diff);
-    SHTONA(pad, 2, free_sz - diff);
+    int diff = (int )new_sz - (sni_sz - 5);
+    avail -= diff;
     
-    char *host_end = sni + 9 + old_sz;
-    int oth_sz = bsize - (sni_offs + 9 + old_sz);
+    if (diff < 0 && avail > 0) {
+        resize_sni(buffer, n, sni_offs, sni_sz, new_sz);
+        diff = 0;
+    }
+    if (avail) {
+        avail -= resize_ech_ext(buffer, n, skip, avail);
+    }
+    uint16_t exts[] = { 
+        0x0015, // padding
+        0x0031, // post_handshake_auth
+        0x0010, // ALPN
+        0x001c, // record_size_limit
+        0x0023, // session_ticket
+        0x0005, // status_request
+        0x0022, // delegated_credentials
+        0x0012, // signed_certificate_timestamp
+        0x001b, // compress_certificate
+        0
+    };
+    for (uint16_t *e = exts; avail && avail < 4; e++) {
+        if (!*e) {
+            return -1;
+        }
+        avail += remove_tls_ext(buffer, n, skip, *e);
+    }
+    if (!(sni_offs = find_tls_ext_offset(0x00, buffer, n, skip))) {
+        return -1;
+    }
+    if (diff) {
+        resize_sni(buffer, n, sni_offs, sni_sz, new_sz);
+    }
+    copy_name(buffer + sni_offs + 9, host, new_sz);
     
-    memmove(host_end + diff, host_end, oth_sz);
-    memcpy(sni + 9, host, new_sz);
+    if (avail >= 4) {
+        SHTONA(buffer, 5 + r_sz - avail, 0x0015);
+        SHTONA(buffer, 5 + r_sz - avail + 2, avail - 4);
+        memset(buffer + 5 + r_sz - avail + 4, 0, avail - 4);
+    }
+    SHTONA(buffer, 3, r_sz);
+    SHTONA(buffer, 7, r_sz - 4);
+    SHTONA(buffer, skip, 5 + r_sz - skip - 2);
     return 0;
 }
 
@@ -168,7 +309,11 @@ int parse_tls(const char *buffer, size_t bsize, char **hs)
     if (!is_tls_chello(buffer, bsize)) {
         return 0;
     }
-    size_t sni_offs = chello_ext_offset(0x00, buffer, bsize);
+    size_t skip = find_ext_block(buffer, bsize);
+    if (!skip) {
+        return 0;
+    }
+    size_t sni_offs = find_tls_ext_offset(0x00, buffer, bsize, skip);
     
     if (!sni_offs || (sni_offs + 12) >= bsize) {
         return 0;
@@ -394,3 +539,48 @@ int part_tls(char *buffer, size_t bsize, ssize_t n, long pos)
     SHTONA(buffer, 5 + pos + 3, r_sz - pos);
     return 5;
 }
+
+
+static void gen_rand_array(char *out, size_t len)
+{
+    for (; len; len--, out++) {
+        uint8_t c = rand() % 256;
+        *((uint8_t *)out) = c;
+    }
+}
+
+
+void randomize_tls(char *buffer, ssize_t n)
+{
+    if (n < 44) {
+        return;
+    }
+    uint8_t sid_len = buffer[43];
+    if (n < (44l + sid_len + 2)) {
+        return;
+    }
+    gen_rand_array(buffer + 11, 32);
+    gen_rand_array(buffer + 44, sid_len);
+    
+    size_t skip = find_ext_block(buffer, n);
+    if (!skip) {
+        return;
+    }
+    ssize_t ks_offs = find_tls_ext_offset(0x0033, buffer, n, skip);
+    if (!ks_offs || ks_offs + 6 >= n) {
+        return;
+    }
+    int ks_sz = ANTOHS(buffer, ks_offs + 2);
+    if (ks_offs + 4 + ks_sz > n) {
+        return;
+    }
+    ssize_t g_offs = ks_offs + 4 + 2;
+    while (g_offs + 4 < ks_offs + 4 + ks_sz) {
+        uint16_t g_sz = ANTOHS(buffer, g_offs + 2);
+        if (ks_offs + 4 + g_sz > n) {
+            return;
+        }
+        gen_rand_array(buffer + g_offs + 4, g_sz);
+        g_offs += 4 + g_sz;
+    }
+}

packets.h

@@ -22,7 +22,7 @@ extern char tls_data[517];
 extern char http_data[43];
 extern char udp_data[64];
 
-int change_tls_sni(const char *host, char *buffer, size_t bsize);
+int change_tls_sni(const char *host, char *buffer, ssize_t bsize, ssize_t nn);
 
 bool is_tls_chello(const char *buffer, size_t bsize);
 
@@ -42,6 +42,8 @@ bool is_tls_shello(const char *buffer, size_t bsize);
 
 int part_tls(char *buffer, size_t bsize, ssize_t n, long pos);
 
+void randomize_tls(char *buffer, ssize_t n);
+
 //bool is_dns_req(char *buffer, size_t n);
 
 //bool is_quic_initial(char *buffer, size_t bsize);

params.h

@@ -37,6 +37,9 @@
 #define AUTO_NOBUFF -1
 #define AUTO_NOSAVE 0
 
+#define FM_RAND 1
+#define FM_ORIG 2
+
 enum demode {
     DESYNC_NONE,
     DESYNC_SPLIT,
@@ -67,6 +70,8 @@ struct part {
 struct packet {
      ssize_t size;
      char  *data;
+     ssize_t off;
+     bool dynamic;
 };
 
 struct desync_params {
@@ -74,7 +79,10 @@ struct desync_params {
     bool md5sig;
     struct packet fake_data;
     int udp_fake_count;
-    int fake_offset;
+    struct part fake_offset;
+    int fake_sni_count;
+    const char **fake_sni_list;
+    int fake_mod;
     bool drop_sack;
     char oob_char[2];