Implement TCP fragmentation for HTTP Persistent (keep-alive) sessions.

New option `-k` splits HTTP request into two segments, and either
send only the first one (Windows would retransmit the other one
based on ACK number in ACK reply) or both (with `-n` enabled).

This fixes behaviour on some DPI which trace persistent sessions
but do not reassemble packages.

Makefile

@@ -1,14 +1,17 @@
-CPREFIX = x86_64-w64-mingw32
+ifndef MSYSTEM
+	CPREFIX = x86_64-w64-mingw32-
+endif
+
 WINDIVERTHEADERS = ../../include
 WINDIVERTLIBS = ../binary
 
 TARGET = goodbyedpi.exe
-LIBS = -L $(WINDIVERTLIBS) -lWinDivert -lws2_32
+LIBS = -L$(WINDIVERTLIBS) -lWinDivert -lws2_32
-CC = $(CPREFIX)-gcc
+CC = $(CPREFIX)gcc
-CCWINDRES = $(CPREFIX)-windres
+CCWINDRES = $(CPREFIX)windres
-CFLAGS = -Wall -I $(WINDIVERTHEADERS) -L $(WINDIVERTLIBS) \
+CFLAGS = -Wall -Wextra -I$(WINDIVERTHEADERS) -L$(WINDIVERTLIBS) \
          -O2 -pie -fPIE -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2
-LDFLAGS = -pie
+LDFLAGS = -Wl,-O1,--sort-common,--as-needed
 
 .PHONY: default all clean
 
@@ -27,7 +30,7 @@ manifest:
 .PRECIOUS: $(TARGET) $(OBJECTS)
 
 $(TARGET): $(OBJECTS)
-	$(CC) $(OBJECTS) -Wall $(LIBS) -s -o $@
+	$(CC) $(OBJECTS) -Wall $(LDFLAGS) $(LIBS) -s -o $@
 
 clean:
 	-rm -f *.o

README.md

@@ -18,22 +18,27 @@ Usage: goodbyedpi.exe [OPTION...]
  -s          remove space between host header and its value
  -m          mix Host header case (test.com -> tEsT.cOm)
  -f [value]  set HTTP fragmentation to value
+ -k [value]  enable HTTP persistent (keep-alive) fragmentation and set it to value
+ -n          do not wait for first segment ACK when -k is enabled
  -e [value]  set HTTPS fragmentation to value
  -a          additional space between Method and Request-URI (enables -s, may break sites)
  -w          try to find and parse HTTP traffic on all processed ports (not only on port 80)
- --port      additional TCP port to perform fragmentation on (and HTTP tricks with -w)
+ --port      [value]    additional TCP port to perform fragmentation on (and HTTP tricks with -w)
- --dns-addr  redirect UDP DNS requests to the supplied IP address (experimental)
+ --dns-addr  [value]    redirect UDP DNS requests to the supplied IP address (experimental)
- --dns-port  redirect UDP DNS requests to the supplied port (53 by default)
+ --dns-port  [value]    redirect UDP DNS requests to the supplied port (53 by default)
+ --dns-verb             print verbose DNS redirection messages
+ --blacklist [txtfile]  perform HTTP tricks only to host names and subdomains from
+                        supplied text file. This option can be supplied multiple times.
 
- -1          -p -r -s -f 2 -e 2 (most compatible mode, default)
+ -1          -p -r -s -f 2 -k 2 -n -e 2 (most compatible mode, default)
- -2          -p -r -s -f 2 -e 40 (better speed yet still compatible)
+ -2          -p -r -s -f 2 -k 2 -n -e 40 (better speed for HTTPS yet still compatible)
- -3          -p -r -s -e 40 (even better speed)
+ -3          -p -r -s -e 40 (better speed for HTTP and HTTPS)
  -4          -p -r -s (best speed)
 ```
 
-Try to run `goodbyedpi.exe -1 -a -m --dns-addr 77.88.8.8 --dns-port 1253` first. This is the most hardcore mode which will show if this program is suitable for your ISP and DPI vendor. If you can open blocked websites with these options, it means your ISP has DPI which can be circumvented. This is the slowest and prone to break websites mode, but suitable for most DPI.
+To check if your ISP's DPI could be circumvented, run `3_all_dnsredir_hardcore.cmd` first. This is the most hardcore mode which will show if this program is suitable for your ISP and DPI vendor at all. If you can open blocked websites with this mode, it means your ISP has DPI which can be circumvented. This is the slowest and prone to break websites mode, but suitable for most DPI.
 
-Try `-1` to see if it works too.
+Try `goodbyedpi -1` to see if it works too.
 
 Then try `goodbyedpi.exe -2`. It should be faster for HTTPS sites. Mode `-3` speed ups HTTP websites.
 
@@ -50,6 +55,7 @@ Most Passive DPI send HTTP 302 Redirect if you try to access blocked website ove
 Active DPI is more tricky to fool. Currently the software uses 4 methods to circumvent Active DPI:
 
 * TCP-level fragmentation for first data packet
+* TCP-level fragmentation for persistent (keep-alive) HTTP sessions
 * Replacing `Host` header with `hoSt`
 * Removing space between header name and value in `Host` header
 * Adding additional space between HTTP Method (GET, POST etc) and URI
@@ -65,11 +71,11 @@ This project can be build using **GNU Make** and [**mingw**](https://mingw-w64.o
 
 To build x86 exe run:
 
-`make CPREFIX=i686-w64-mingw32 WINDIVERTHEADERS=/path/to/windivert/include WINDIVERTLIBS=/path/to/windivert/x86`
+`make CPREFIX=i686-w64-mingw32- WINDIVERTHEADERS=/path/to/windivert/include WINDIVERTLIBS=/path/to/windivert/x86`
 
 And for x86_64:
 
-`make CPREFIX=x86_64-w64-mingw32 WINDIVERTHEADERS=/path/to/windivert/include WINDIVERTLIBS=/path/to/windivert/amd64`
+`make CPREFIX=x86_64-w64-mingw32- WINDIVERTHEADERS=/path/to/windivert/include WINDIVERTLIBS=/path/to/windivert/amd64`
 
 # How to install as Windows Service
 

blackwhitelist.c

@@ -0,0 +1,110 @@
+/*
+ * Blacklist for GoodbyeDPI HTTP DPI circumvention tricks
+ *
+ * This is a simple domain hash table.
+ * Domain records are added from a text file, where every
+ * domain is separated with a new line.
+ */
+#include <windows.h>
+#include <stdio.h>
+#include "goodbyedpi.h"
+#include "uthash.h"
+#include "getline.h"
+
+typedef struct blackwhitelist_record {
+    const char *host;
+    UT_hash_handle hh;   /* makes this structure hashable */
+} blackwhitelist_record_t;
+
+static blackwhitelist_record_t *blackwhitelist = NULL;
+
+static int check_get_hostname(const char *host) {
+    blackwhitelist_record_t *tmp_record = NULL;
+    if (!blackwhitelist) return FALSE;
+
+    HASH_FIND_STR(blackwhitelist, host, tmp_record);
+    if (tmp_record) {
+        debug("check_get_hostname found host\n");
+        return TRUE;
+    }
+    debug("check_get_hostname host not found\n");
+    return FALSE;
+}
+
+static int add_hostname(const char *host) {
+    if (!host)
+        return FALSE;
+
+    int host_len = strlen(host);
+
+    blackwhitelist_record_t *tmp_record = malloc(sizeof(blackwhitelist_record_t));
+    char *host_c = malloc(host_len + 1);
+
+    if (!check_get_hostname(host)) {
+        strncpy(host_c, host, host_len);
+        host_c[host_len] = '\0';
+        tmp_record->host = host_c;
+        HASH_ADD_KEYPTR(hh, blackwhitelist, tmp_record->host,
+                        strlen(tmp_record->host), tmp_record);
+        debug("Added host %s\n", host_c);
+        return TRUE;
+    }
+    debug("Not added host %s\n", host);
+    free(tmp_record);
+    free(host_c);
+    return FALSE;
+}
+
+int blackwhitelist_load_list(const char *filename) {
+    char *line = malloc(HOST_MAXLEN + 1);
+    size_t linelen = HOST_MAXLEN + 1;
+    int cnt = 0;
+    ssize_t read;
+
+    FILE *fp = fopen(filename, "r");
+    if (!fp) return FALSE;
+
+    while ((read = getline(&line, &linelen, fp)) != -1) {
+        /* works with both \n and \r\n */
+        line[strcspn(line, "\r\n")] = '\0';
+        if (strlen(line) > HOST_MAXLEN) {
+            printf("WARNING: host %s exceeds maximum host length and has not been added\n",
+                line);
+            continue;
+        }
+        if (strlen(line) < 4)
+            continue;
+        if (add_hostname(line))
+            cnt++;
+    }
+    free(line);
+    if (!blackwhitelist) return FALSE;
+    printf("Loaded %d hosts from file %s\n", cnt, filename);
+    fclose(fp);
+    return TRUE;
+}
+
+int blackwhitelist_check_hostname(const char *host_addr, int host_len) {
+    char current_host[HOST_MAXLEN + 1];
+    char *tokenized_host = NULL;
+
+    if (host_len > HOST_MAXLEN) return FALSE;
+    if (host_addr && host_len) {
+        memcpy(current_host, host_addr, host_len);
+        current_host[host_len] = '\0';
+    }
+
+    if (check_get_hostname(current_host))
+            return TRUE;
+
+    tokenized_host = strchr(current_host, '.');
+    while (tokenized_host != NULL && tokenized_host < (current_host + HOST_MAXLEN)) {
+        /* Search hostname only if there is next token */
+        if (strchr(tokenized_host + 1, '.') && check_get_hostname(tokenized_host + 1))
+            return TRUE;
+        tokenized_host = strchr(tokenized_host + 1, '.');
+    }
+
+    debug("____blackwhitelist_check_hostname FALSE: host %s\n", current_host);
+    return FALSE;
+}

blackwhitelist.h

@@ -0,0 +1,2 @@
+int blackwhitelist_load_list(const char *filename);
+int blackwhitelist_check_hostname(const char *host_addr, int host_len);

dnsredir.c

@@ -13,6 +13,7 @@
 #include <windows.h>
 #include <time.h>
 #include <stdio.h>
+#include "goodbyedpi.h"
 #include "dnsredir.h"
 #include "uthash.h"
 
@@ -21,14 +22,6 @@
 
 #define DNS_CLEANUP_INTERVAL_SEC 30
 
-#ifndef debug
-#define debug(...) do {} while (0)
-#endif
-
-#ifndef debug
-#define debug(...) printf(...)
-#endif
-
 /* HACK!
  * uthash uses strlen() for HASH_FIND_STR.
  * We have null bytes in our key, so we can't use strlen()
@@ -50,6 +43,22 @@ typedef struct udp_connrecord {
 static time_t last_cleanup = 0;
 static udp_connrecord_t *conntrack = NULL;
 
+void flush_dns_cache() {
+    BOOL WINAPI (*DnsFlushResolverCache)();
+
+    HMODULE dnsapi = LoadLibrary("dnsapi.dll");
+    if (dnsapi == NULL)
+    {
+        printf("Can't load dnsapi.dll to flush DNS cache!\n");
+        exit(EXIT_FAILURE);
+    }
+
+    DnsFlushResolverCache = (void*)GetProcAddress(dnsapi, "DnsFlushResolverCache");
+    if (DnsFlushResolverCache == NULL || !DnsFlushResolverCache())
+        printf("Can't flush DNS cache!");
+    FreeLibrary(dnsapi);
+}
+
 inline static void construct_key(const uint32_t srcip, const uint16_t srcport, char *key) {
     debug("Construct key enter\n");
     if (key) {
@@ -92,10 +101,10 @@ static int check_get_udp_conntrack_key(const char *key, udp_connrecord_t **connr
 
 static int add_udp_conntrack(const uint32_t srcip, const uint16_t srcport,
                              const uint32_t dstip, const uint16_t dstport) {
-    udp_connrecord_t *tmp_connrecord = malloc(sizeof(udp_connrecord_t));
     if (!(srcip && srcport && dstip && dstport))
         return FALSE;
 
+    udp_connrecord_t *tmp_connrecord = malloc(sizeof(udp_connrecord_t));
     construct_key(srcip, srcport, tmp_connrecord->key);
 
     if (!check_get_udp_conntrack_key(tmp_connrecord->key, NULL)) {
@@ -107,6 +116,7 @@ static int add_udp_conntrack(const uint32_t srcip, const uint16_t srcport,
         return TRUE;
     }
     debug("Not added UDP conntrack\n");
+    free(tmp_connrecord);
     return FALSE;
 }
 
@@ -130,6 +140,20 @@ void dns_cleanup() {
     }
 }
 
+int dns_is_dns_packet(const char *packet_data, const UINT packet_dataLen, const int outgoing) {
+    if (packet_dataLen < 16) return FALSE;
+
+    if (outgoing && (ntohs(*(const uint16_t*)(packet_data + 2)) & 0xFA00) == 0 &&
+        (ntohs(*(const uint32_t*)(packet_data + 6))) == 0) {
+        return TRUE;
+    }
+    else if (!outgoing &&
+        (ntohs(*(const uint16_t*)(packet_data + 2)) & 0xF800) == 0x8000) {
+        return TRUE;
+    }
+    return FALSE;
+}
+
 int dns_handle_outgoing(const uint32_t srcip, const uint16_t srcport,
                         const uint32_t dstip, const uint16_t dstport,
                         const char *packet_data, const UINT packet_dataLen) {
@@ -139,8 +163,7 @@ int dns_handle_outgoing(const uint32_t srcip, const uint16_t srcport,
 
     dns_cleanup();
 
-    if ((ntohs(*(const uint16_t*)(packet_data + 2)) & 0xFA00) == 0 &&
+    if (dns_is_dns_packet(packet_data, packet_dataLen, 1)) {
-        (ntohs(*(const uint32_t*)(packet_data + 6))) == 0) {
         /* Looks like DNS request */
         debug("trying to add srcport = %hu, dstport = %hu\n", ntohs(srcport), ntohs(dstport));
         return add_udp_conntrack(srcip, srcport, dstip, dstport);
@@ -150,7 +173,6 @@ int dns_handle_outgoing(const uint32_t srcip, const uint16_t srcport,
 }
 
 int dns_handle_incoming(const uint32_t srcip, const uint16_t srcport,
-                        const uint32_t dstip, const uint16_t dstport,
                         const char *packet_data, const UINT packet_dataLen,
                         conntrack_info_t *conn_info) {
 
@@ -162,7 +184,7 @@ int dns_handle_incoming(const uint32_t srcip, const uint16_t srcport,
 
     dns_cleanup();
 
-    if ((ntohs(*(const uint16_t*)(packet_data + 2)) & 0xF800) == 0x8000) {
+    if (dns_is_dns_packet(packet_data, packet_dataLen, 0)) {
         /* Looks like DNS response */
         construct_key(srcip, srcport, key);
         if (check_get_udp_conntrack_key(key, &tmp_connrecord) && tmp_connrecord) {

dnsredir.h

@@ -8,10 +8,12 @@ typedef struct conntrack_info {
 } conntrack_info_t;
 
 int dns_handle_incoming(const uint32_t srcip, const uint16_t srcport,
-                        const uint32_t dstip, const uint16_t dstport,
                         const char *packet_data, const UINT packet_dataLen,
                         conntrack_info_t *conn_info);
 
 int dns_handle_outgoing(const uint32_t srcip, const uint16_t srcport,
                         const uint32_t dstip, const uint16_t dstport,
                         const char *packet_data, const UINT packet_dataLen);
+
+void flush_dns_cache();
+int dns_is_dns_packet(const char *packet_data, const UINT packet_dataLen, const int outgoing);

getline.c

@@ -0,0 +1,92 @@
+/*	$NetBSD: getdelim.c,v 1.2 2015/12/25 20:12:46 joerg Exp $	*/
+/*	NetBSD-src: getline.c,v 1.2 2014/09/16 17:23:50 christos Exp 	*/
+
+/*-
+ * Copyright (c) 2011 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Christos Zoulas.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "getline.h"
+
+#if !HAVE_GETDELIM
+
+ssize_t
+getdelim(char **buf, size_t *bufsiz, int delimiter, FILE *fp)
+{
+	char *ptr, *eptr;
+
+
+	if (*buf == NULL || *bufsiz == 0) {
+		*bufsiz = BUFSIZ;
+		if ((*buf = malloc(*bufsiz)) == NULL)
+			return -1;
+	}
+
+	for (ptr = *buf, eptr = *buf + *bufsiz;;) {
+		int c = fgetc(fp);
+		if (c == -1) {
+			if (feof(fp)) {
+				ssize_t diff = (ssize_t)(ptr - *buf);
+				if (diff != 0) {
+					*ptr = '\0';
+					return diff;
+				}
+			}
+			return -1;
+		}
+		*ptr++ = c;
+		if (c == delimiter) {
+			*ptr = '\0';
+			return ptr - *buf;
+		}
+		if (ptr + 2 >= eptr) {
+			char *nbuf;
+			size_t nbufsiz = *bufsiz * 2;
+			ssize_t d = ptr - *buf;
+			if ((nbuf = realloc(*buf, nbufsiz)) == NULL)
+				return -1;
+			*buf = nbuf;
+			*bufsiz = nbufsiz;
+			eptr = nbuf + nbufsiz;
+			ptr = nbuf + d;
+		}
+	}
+}
+
+#endif
+
+#if !HAVE_GETLINE
+
+ssize_t
+getline(char **buf, size_t *bufsiz, FILE *fp)
+{
+	return getdelim(buf, bufsiz, '\n', fp);
+}
+
+#endif

getline.h

@@ -0,0 +1,7 @@
+#if !HAVE_GETDELIM
+ssize_t	getdelim(char **, size_t *, int, FILE *);
+#endif
+
+#if !HAVE_GETLINE
+ssize_t	getline(char **, size_t *, FILE *);
+#endif

goodbyedpi.c

@@ -10,7 +10,9 @@
 #include <string.h>
 #include <getopt.h>
 #include "windivert.h"
+#include "goodbyedpi.h"
 #include "dnsredir.h"
+#include "blackwhitelist.h"
 
 #define die() do { printf("Something went wrong!\n" \
     "Make sure you're running this program with administrator privileges\n"); \
@@ -20,7 +22,6 @@
 #define MAX_PACKET_SIZE 9016
 #define IPV4_HDR_LEN 20
 #define TCP_HDR_LEN 20
-#define IPV4_TOTALLEN_OFFSET 2
 #define TCP_WINDOWSIZE_OFFSET 14
 
 #define DIVERT_NO_LOCALNETS_DST "(" \
@@ -38,6 +39,22 @@
                    "(ip.SrcAddr < 169.254.0.0 or ip.SrcAddr > 169.254.255.255)" \
                    ")"
 
+#define SET_HTTP_FRAGMENT_SIZE_OPTION(fragment_size) do { \
+    if (!http_fragment_size) { \
+        http_fragment_size = fragment_size; \
+        if (http_fragment_size <= 0 || http_fragment_size > 65535) { \
+            printf(fragment_size_message); \
+            exit(EXIT_FAILURE); \
+        } \
+    } \
+    else if (http_fragment_size != fragment_size) { \
+        printf( \
+            "WARNING: HTTP fragment size is already set to %d, not changing.\n", \
+            http_fragment_size \
+        ); \
+    } \
+} while (0)
+
 static HANDLE filters[MAX_FILTERS];
 static int filter_num = 0;
 static const char *http10_redirect_302 = "HTTP/1.0 302 ";
@@ -61,10 +78,13 @@ static struct option long_options[] = {
     {"port",      required_argument, 0,  'z' },
     {"dns-addr",  required_argument, 0,  'd' },
     {"dns-port",  required_argument, 0,  'g' },
+    {"dns-verb",  no_argument,       0,  'v' },
+    {"blacklist", required_argument, 0,  'b' },
     {0,           0,                 0,   0  }
 };
 
-static char *filter_string = "(ip and tcp and "
+static char *filter_string = NULL;
+static char *filter_string_template = "(ip and tcp and "
         "(inbound and (("
          "((ip.Id == 0x0001 or ip.Id == 0x0000) and tcp.SrcPort == 80 and tcp.Ack) or "
          "((tcp.SrcPort == 80 or tcp.SrcPort == 443) and tcp.Ack and tcp.Syn)"
@@ -115,6 +135,7 @@ static HANDLE init(char *filter, UINT64 flags) {
                   NULL, GetLastError(), MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
                   (LPTSTR)&errormessage, 0, NULL);
     printf("%s", errormessage);
+    free(errormessage);
     return NULL;
 }
 
@@ -132,7 +153,7 @@ static void deinit_all() {
     }
 }
 
-static void sigint_handler(int sig) {
+static void sigint_handler(int sig __attribute__((unused))) {
     deinit_all();
     exit(EXIT_SUCCESS);
 }
@@ -202,19 +223,23 @@ static void change_window_size(const char *pkt, int size) {
 }
 
 /* HTTP method end without trailing space */
-static PVOID find_http_method_end(const char *pkt, int offset) {
+static PVOID find_http_method_end(const char *pkt, int http_frag, int *is_fragmented) {
-    int i;
+    unsigned int i;
     for (i = 0; i<(sizeof(http_methods) / sizeof(*http_methods)); i++) {
         if (memcmp(pkt, http_methods[i], strlen(http_methods[i])) == 0) {
+            if (is_fragmented)
+                *is_fragmented = 0;
             return (char*)pkt + strlen(http_methods[i]) - 1;
         }
         /* Try to find HTTP method in a second part of fragmented packet */
-        if ((offset == 1 || offset == 2) &&
+        if ((http_frag == 1 || http_frag == 2) &&
-            memcmp(pkt, http_methods[i] + offset,
+            memcmp(pkt, http_methods[i] + http_frag,
-                   strlen(http_methods[i]) - offset) == 0
+                   strlen(http_methods[i]) - http_frag) == 0
            )
         {
-            return (char*)pkt + strlen(http_methods[i]) - offset - 1;
+            if (is_fragmented)
+                *is_fragmented = 1;
+            return (char*)pkt + strlen(http_methods[i]) - http_frag - 1;
         }
     }
     return NULL;
@@ -237,20 +262,29 @@ int main(int argc, char *argv[]) {
     conntrack_info_t dns_conn_info;
 
     int do_passivedpi = 0, do_fragment_http = 0,
+        do_fragment_http_persistent = 0,
+        do_fragment_http_persistent_nowait = 0,
         do_fragment_https = 0, do_host = 0,
         do_host_removespace = 0, do_additional_space = 0,
         do_http_allports = 0,
-        do_host_mixedcase = 0, do_dns_redirect = 0;
+        do_host_mixedcase = 0, do_dns_redirect = 0,
+        do_dns_verb = 0, do_blacklist = 0;
     int http_fragment_size = 2;
     int https_fragment_size = 2;
     uint32_t dns_addr = 0;
     uint16_t dns_port = htons(53);
     char *host_addr, *useragent_addr, *method_addr;
     int host_len, useragent_len;
+    int http_req_fragmented;
 
     char *hdr_name_addr = NULL, *hdr_value_addr = NULL;
     int hdr_value_len;
 
+    if (filter_string == NULL) {
+        filter_string = malloc(strlen(filter_string_template) + 1);
+        strcpy(filter_string, filter_string_template);
+    }
+
     printf("GoodbyeDPI: Passive DPI blocker and Active DPI circumvention utility\n");
 
     if (argc == 1) {
@@ -259,21 +293,26 @@ int main(int argc, char *argv[]) {
             = do_fragment_http = do_fragment_https = 1;
     }
 
-    while ((opt = getopt_long(argc, argv, "1234prsaf:e:mw", long_options, NULL)) != -1) {
+    while ((opt = getopt_long(argc, argv, "1234prsaf:e:mwk:n", long_options, NULL)) != -1) {
         switch (opt) {
             case '1':
                 do_passivedpi = do_host = do_host_removespace \
-                = do_fragment_http = do_fragment_https = 1;
+                = do_fragment_http = do_fragment_https \
+                = do_fragment_http_persistent \
+                = do_fragment_http_persistent_nowait = 1;
                 break;
             case '2':
                 do_passivedpi = do_host = do_host_removespace \
-                = do_fragment_http = do_fragment_https = 1;
+                = do_fragment_http = do_fragment_https \
+                = do_fragment_http_persistent \
+                = do_fragment_http_persistent_nowait = 1;
                 https_fragment_size = 40;
                 break;
             case '3':
                 do_passivedpi = do_host = do_host_removespace \
                 = do_fragment_https = 1;
                 https_fragment_size = 40;
+                break;
             case '4':
                 do_passivedpi = do_host = do_host_removespace = 1;
                 break;
@@ -295,11 +334,14 @@ int main(int argc, char *argv[]) {
                 break;
             case 'f':
                 do_fragment_http = 1;
-                http_fragment_size = atoi(optarg);
+                SET_HTTP_FRAGMENT_SIZE_OPTION(atoi(optarg));
-                if (http_fragment_size <= 0 || http_fragment_size > 65535) {
+                break;
-                    printf(fragment_size_message);
+            case 'k':
-                    exit(EXIT_FAILURE);
+                do_fragment_http_persistent = 1;
-                }
+                SET_HTTP_FRAGMENT_SIZE_OPTION(atoi(optarg));
+                break;
+            case 'n':
+                do_fragment_http_persistent_nowait = 1;
                 break;
             case 'e':
                 do_fragment_https = 1;
@@ -319,27 +361,49 @@ int main(int argc, char *argv[]) {
                     printf("Port parameter error!\n");
                     exit(EXIT_FAILURE);
                 }
-                add_filter_str(IPPROTO_TCP, i);
+                if (i != 80 && i != 443)
+                    add_filter_str(IPPROTO_TCP, i);
                 i = 0;
                 break;
             case 'd':
-                do_dns_redirect = 1;
+                if (!do_dns_redirect) {
-                dns_addr = inet_addr(optarg);
+                    do_dns_redirect = 1;
-                if (!dns_addr) {
+                    dns_addr = inet_addr(optarg);
-                    printf("DNS address parameter error!\n");
+                    if (!dns_addr) {
-                    exit(EXIT_FAILURE);
+                        printf("DNS address parameter error!\n");
+                        exit(EXIT_FAILURE);
+                    }
+                    add_filter_str(IPPROTO_UDP, 53);
+                    flush_dns_cache();
                 }
-                add_filter_str(IPPROTO_UDP, 53);
                 break;
             case 'g':
+                if (!do_dns_redirect) {
+                    printf("--dns-port should be used with --dns-addr!\n"
+                        "Make sure you use --dns-addr and pass it before "
+                        "--dns-port\n");
+                    exit(EXIT_FAILURE);
+                }
                 dns_port = atoi(optarg);
-                if (dns_port <= 0 || dns_port > 65535) {
+                if (atoi(optarg) <= 0 || atoi(optarg) > 65535) {
                     printf("DNS port parameter error!\n");
                     exit(EXIT_FAILURE);
                 }
-                add_filter_str(IPPROTO_UDP, dns_port);
+                if (dns_port != 53) {
+                    add_filter_str(IPPROTO_UDP, dns_port);
+                }
                 dns_port = ntohs(dns_port);
                 break;
+            case 'v':
+                do_dns_verb = 1;
+                break;
+            case 'b':
+                do_blacklist = 1;
+                if (!blackwhitelist_load_list(optarg)) {
+                    printf("Can't load blacklist from file!\n");
+                    exit(EXIT_FAILURE);
+                }
+                break;
             default:
                 printf("Usage: goodbyedpi.exe [OPTION...]\n"
                 " -p          block passive DPI\n"
@@ -348,27 +412,34 @@ int main(int argc, char *argv[]) {
                 " -a          additional space between Method and Request-URI (enables -s, may break sites)\n"
                 " -m          mix Host header case (test.com -> tEsT.cOm)\n"
                 " -f [value]  set HTTP fragmentation to value\n"
+                " -k [value]  enable HTTP persistent (keep-alive) fragmentation and set it to value\n"
+                " -n          do not wait for first segment ACK when -k is enabled\n"
                 " -e [value]  set HTTPS fragmentation to value\n"
                 " -w          try to find and parse HTTP traffic on all processed ports (not only on port 80)\n"
-                " --port      additional TCP port to perform fragmentation on (and HTTP tricks with -w)\n"
+                " --port      [value]    additional TCP port to perform fragmentation on (and HTTP tricks with -w)\n"
-                " --dns-addr  redirect UDP DNS requests to the supplied IP address (experimental)\n"
+                " --dns-addr  [value]    redirect UDP DNS requests to the supplied IP address (experimental)\n"
-                " --dns-port  redirect UDP DNS requests to the supplied port (53 by default)\n"
+                " --dns-port  [value]    redirect UDP DNS requests to the supplied port (53 by default)\n"
+                " --dns-verb             print verbose DNS redirection messages\n"
+                " --blacklist [txtfile]  perform HTTP tricks only to host names and subdomains from\n"
+                "                        supplied text file. This option can be supplied multiple times.\n"
                 "\n"
-                " -1          -p -r -s -f 2 -e 2 (most compatible mode, default)\n"
+                " -1          -p -r -s -f 2 -k 2 -n -e 2 (most compatible mode, default)\n"
-                " -2          -p -r -s -f 2 -e 40 (better speed yet still compatible)\n"
+                " -2          -p -r -s -f 2 -k 2 -n -e 40 (better speed for HTTPS yet still compatible)\n"
-                " -3          -p -r -s -e 40 (even better speed)\n"
+                " -3          -p -r -s -e 40 (better speed for HTTP and HTTPS)\n"
                 " -4          -p -r -s (best speed)\n");
                 exit(EXIT_FAILURE);
         }
     }
 
-    printf("Block passive: %d, Fragment HTTP: %d, Fragment HTTPS: %d, "
+    printf("Block passive: %d, Fragment HTTP: %d, Fragment persistent HTTP: %d, "
+           "Fragment HTTPS: %d, "
            "hoSt: %d, Host no space: %d, Additional space: %d, Mix Host: %d, "
-           "HTTP AllPorts: %d, DNS redirect: %d\n",
+           "HTTP AllPorts: %d, HTTP Persistent Nowait: %d, DNS redirect: %d\n",
            do_passivedpi, (do_fragment_http ? http_fragment_size : 0),
+           (do_fragment_http_persistent ? http_fragment_size : 0),
            (do_fragment_https ? https_fragment_size : 0),
            do_host, do_host_removespace, do_additional_space, do_host_mixedcase,
-           do_http_allports, do_dns_redirect
+           do_http_allports, do_fragment_http_persistent_nowait, do_dns_redirect
           );
 
     if (do_fragment_http && http_fragment_size > 2) {
@@ -435,17 +506,69 @@ int main(int argc, char *argv[]) {
                         packet_dataLen > 16 &&
                         (do_http_allports ? 1 : (ppTcpHdr->DstPort == htons(80))) &&
                         find_http_method_end(packet_data,
-                                             (do_fragment_http ? http_fragment_size : 0)) &&
+                                             (do_fragment_http ? http_fragment_size : 0),
-                        (do_host || do_host_removespace || do_host_mixedcase))
+                                             &http_req_fragmented) &&
+                        (do_host || do_host_removespace ||
+                        do_host_mixedcase || do_fragment_http_persistent))
                 {
 
                     /* Find Host header */
                     if (find_header_and_get_info(packet_data, packet_dataLen,
-                        http_host_find, &hdr_name_addr, &hdr_value_addr, &hdr_value_len)) {
+                        http_host_find, &hdr_name_addr, &hdr_value_addr, &hdr_value_len) &&
+                        hdr_value_len > 0 && hdr_value_len <= HOST_MAXLEN &&
+                        (do_blacklist ? blackwhitelist_check_hostname(hdr_value_addr, hdr_value_len) : 1))
+                    {
                         host_addr = hdr_value_addr;
                         host_len = hdr_value_len;
 
-                        if (do_host_mixedcase && host_len > 0 && host_len <= 253) {
+                        /*
+                         * Handle new HTTP request in new
+                         * connection (when Window Size modification disabled)
+                         * or already established connection (keep-alive).
+                         * We split HTTP request into two packets: one of http_fragment_size length
+                         * and another of original_size - http_fragment_size length.
+                         *
+                         * The second packet of a splitted part is not really needed to be sent
+                         * as Windows understand that is hasn't been sent by checking
+                         * ack number of received packet and retransmitting missing part again,
+                         * but it's better to send it anyway since it eliminates one RTT.
+                         */
+                        if (do_fragment_http_persistent && !http_req_fragmented) {
+                            ppIpHdr->Length = htons(
+                                ntohs(ppIpHdr->Length) -
+                                packet_dataLen + http_fragment_size
+                            );
+                            WinDivertHelperCalcChecksums(
+                                packet, packetLen - packet_dataLen + http_fragment_size, 0
+                            );
+                            WinDivertSend(
+                                w_filter, packet,
+                                packetLen - packet_dataLen + http_fragment_size,
+                                &addr, NULL
+                            );
+                            if (do_fragment_http_persistent_nowait) {
+                                ppIpHdr->Length = htons(
+                                    ntohs(ppIpHdr->Length) -
+                                    http_fragment_size + packet_dataLen - http_fragment_size
+                                );
+                                memmove(packet_data,
+                                        packet_data + http_fragment_size,
+                                        packet_dataLen);
+                                packet_dataLen -= http_fragment_size;
+                                packetLen -= http_fragment_size;
+                                hdr_value_addr -= http_fragment_size;
+                                hdr_name_addr -= http_fragment_size;
+                                host_addr = hdr_value_addr;
+
+                                ppTcpHdr->SeqNum = htonl(ntohl(ppTcpHdr->SeqNum) + http_fragment_size);
+                                should_recalc_checksum = 1;
+                            }
+                            else {
+                                continue;
+                            }
+                        }
+
+                        if (do_host_mixedcase) {
                             mix_case(host_addr, host_len);
                             should_recalc_checksum = 1;
                         }
@@ -462,7 +585,8 @@ int main(int argc, char *argv[]) {
                         if (do_additional_space && do_host_removespace) {
                             /* End of "Host:" without trailing space */
                             method_addr = find_http_method_end(packet_data,
-                                                            (do_fragment_http ? http_fragment_size : 0));
+                                                            (do_fragment_http ? http_fragment_size : 0),
+                                                            NULL);
 
                             if (method_addr) {
                                 memmove(method_addr + 1, method_addr,
@@ -486,15 +610,15 @@ int main(int argc, char *argv[]) {
                                  *
                                  * Nothing is done if User-Agent header is missing.
                                  */
-                                if (host_len > 0 && host_len <= 253 &&
+                                if (useragent_addr && useragent_len > 0) {
-                                    useragent_addr && useragent_len > 0) {
                                     /* useragent_addr is in the beginning of User-Agent value */
 
                                     if (useragent_addr > host_addr) {
                                         /* Move one byte to the LEFT from "Host:"
                                         * to the end of User-Agent
                                         */
-                                        memmove(host_addr - 1, host_addr, useragent_len);
+                                        memmove(host_addr - 1, host_addr,
+                                                (PVOID)useragent_addr + useragent_len - (PVOID)host_addr);
                                         host_addr -= 1;
                                         /* Put space in the end of User-Agent header */
                                         *(char*)((PVOID)useragent_addr + useragent_len - 1) = ' ';
@@ -509,13 +633,13 @@ int main(int argc, char *argv[]) {
                                         */
                                         memmove((PVOID)useragent_addr + useragent_len + 1,
                                                 (PVOID)useragent_addr + useragent_len,
-                                                useragent_len - 1);
+                                                (PVOID)host_addr - 1 - ((PVOID)useragent_addr + useragent_len));
                                         /* Put space in the end of User-Agent header */
                                         *(char*)((PVOID)useragent_addr + useragent_len) = ' ';
                                         should_recalc_checksum = 1;
                                         //printf("Replaced Host header!\n");
                                     }
-                                } /* if (host_len <= 253 && useragent_addr) */
+                                } /* if (host_len <= HOST_MAXLEN && useragent_addr) */
                             } /* if (find_header_and_get_info http_useragent) */
                         } /* else if (do_host_removespace) */
                     } /* if (find_header_and_get_info http_host) */
@@ -529,6 +653,10 @@ int main(int argc, char *argv[]) {
                 if (addr.Direction == WINDIVERT_DIRECTION_INBOUND &&
                     ppTcpHdr->Syn == 1 && ppTcpHdr->Ack == 1) {
                     //printf("Changing Window Size!\n");
+                    /*
+                     * Window Size is changed even if do_fragment_http_persistent
+                     * is enabled as there could be non-HTTP data on port 80
+                     */
                     if (do_fragment_http && ppTcpHdr->SrcPort == htons(80)) {
                         change_window_size(packet, http_fragment_size);
                         should_recalc_checksum = 1;
@@ -541,12 +669,11 @@ int main(int argc, char *argv[]) {
             }
 
             /* Else if we got UDP packet with data */
-            else if (WinDivertHelperParsePacket(packet, packetLen, &ppIpHdr,
+            else if (do_dns_redirect && WinDivertHelperParsePacket(packet, packetLen, &ppIpHdr,
                 NULL, NULL, NULL, NULL, &ppUdpHdr, &packet_data, &packet_dataLen)) {
 
                 if (addr.Direction == WINDIVERT_DIRECTION_INBOUND) {
                     if (dns_handle_incoming(ppIpHdr->DstAddr, ppUdpHdr->DstPort,
-                                        ppIpHdr->SrcAddr, ppUdpHdr->SrcPort,
                                         packet_data, packet_dataLen,
                                         &dns_conn_info))
                     {
@@ -558,7 +685,13 @@ int main(int argc, char *argv[]) {
                         should_recalc_checksum = 1;
                     }
                     else {
-                        printf("[DNS] Error handling incoming packet!\n");
+                        if (dns_is_dns_packet(packet_data, packet_dataLen, 0))
+                            should_reinject = 0;
+
+                        if (do_dns_verb && !should_reinject) {
+                            printf("[DNS] Error handling incoming packet: srcport = %hu, dstport = %hu\n",
+                               ntohs(ppUdpHdr->SrcPort), ntohs(ppUdpHdr->DstPort));
+                        }
                     }
                 }
 
@@ -574,7 +707,13 @@ int main(int argc, char *argv[]) {
                         should_recalc_checksum = 1;
                     }
                     else {
-                        printf("[DNS] Error handling outgoing packet!\n");
+                        if (dns_is_dns_packet(packet_data, packet_dataLen, 1))
+                            should_reinject = 0;
+
+                        if (do_dns_verb && !should_reinject) {
+                            printf("[DNS] Error handling outgoing packet: srcport = %hu, dstport = %hu\n",
+                               ntohs(ppUdpHdr->SrcPort), ntohs(ppUdpHdr->DstPort));
+                        }
                     }
                 }
             }

goodbyedpi.h

@@ -0,0 +1,7 @@
+#define HOST_MAXLEN 253
+
+#ifndef DEBUG
+#define debug(...) do {} while (0)
+#else
+#define debug(...) printf(__VA_ARGS__)
+#endif