Replace char* with const char* where appropriate

Makefile

@@ -1,8 +1,13 @@
+CPREFIX = x86_64-w64-mingw32
+WINDIVERTHEADERS = ../../include
+WINDIVERTLIBS = ../binary
+
 TARGET = goodbyedpi.exe
-LIBS = -L ../binary -lWinDivert -lws2_32
-CC = x86_64-w64-mingw32-gcc
-CCWINDRES = x86_64-w64-mingw32-windres
-CFLAGS = -Wall -I ../../include -L ../binary -O2
+LIBS = -L $(WINDIVERTLIBS) -lWinDivert -lws2_32
+CC = $(CPREFIX)-gcc
+CCWINDRES = $(CPREFIX)-windres
+CFLAGS = -Wall -I $(WINDIVERTHEADERS) -L $(WINDIVERTLIBS) \
+         -O2 -fPIE -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2
 
 .PHONY: default all clean
 

README.md

@@ -3,7 +3,7 @@ GoodbyeDPI — Passive Deep Packet Inspection blocker and Active DPI circumventi
 
 This software designed to bypass Deep Packet Inspection systems found in many Internet Service Providers which block access to certain websites.
 
-It handles DPI connected using optical splitter or port mirroring (**Passive DPI**) which do not block any data but just replying faster then requested destination, and **Active DPI** connected in sequence.
+It handles DPI connected using optical splitter or port mirroring (**Passive DPI**) which do not block any data but just replying faster than requested destination, and **Active DPI** connected in sequence.
 
 **Windows 7, 8, 8.1 and 10** with administrator privileges required.
 
@@ -11,11 +11,31 @@ It handles DPI connected using optical splitter or port mirroring (**Passive DPI
 
 Download [latest version from Releases page](https://github.com/ValdikSS/GoodbyeDPI/releases) and run.
 
+```
+Usage: goodbyedpi.exe [OPTION...]
+ -p          block passive DPI
+ -r          replace Host with hoSt
+ -s          remove space between host header and its value
+ -f [value]  set HTTP fragmentation to value
+ -e [value]  set HTTPS fragmentation to value
+
+ -1          enables all options, -f 2 -e 2 (most compatible mode, default)
+ -2          enables all options, -f 2 -e 40 (better speed yet still compatible)
+ -3          all options except HTTP fragmentation, -e 40 (even better speed)
+ -4          all options except fragmentation (best speed)
+```
+
+Try to run `goodbyedpi.exe` without any arguments first. If you can open blocked websites it means your ISP has DPI which can be circumvented. This is the slowest mode.
+
+Then try `goodbyedpi.exe -2`. It should be faster for HTTPS sites. Mode `-3` speed ups HTTP websites.
+
+Use `goodbyedpi.exe -4` if it works for your ISP's DPI. This is the fastest mode but not compatible with every DPI.
+
 # How does it work
 
 ### Passive DPI
 
-Most Passive DPI send HTTP 301 Redirect if you try to access blocked website over HTTP and TCP Reset in case of HTTPS, faster then destination website. Packets sent by DPI have always have IP Identification field equal to `0x0000` or `0x0001`, as seen with Russian providers. These packets are blocked by GoodbyeDPI.
+Most Passive DPI send HTTP 301 Redirect if you try to access blocked website over HTTP and TCP Reset in case of HTTPS, faster than destination website. Packets sent by DPI have always have IP Identification field equal to `0x0000` or `0x0001`, as seen with Russian providers. These packets are blocked by GoodbyeDPI.
 
 ### Active DPI
 
@@ -27,6 +47,20 @@ Active DPI is more tricky to fool. Currently the software uses 3 methods to circ
 
 These methods do not break any website as are fully compatible with TCP and HTTP standards, yet it's sufficient to prevent DPI data classification and to circumvent censorship.
 
+The program loads WinDivert driver which uses Windows Filtering Platform to set filters and redirect packets to the userspace. It's running as long as console window is visible and terminates when you close the window.
+
+# How to build from source
+
+This project can be build using **GNU Make** and [**mingw**](https://mingw-w64.org). The only dependency is [WinDivert](https://github.com/basil00/Divert).
+
+To build x86 exe run:
+
+`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`
+
 # Similar projects
 
 [zapret](https://github.com/bol-van/zapret) by @bol-van (for Linux).

goodbyedpi.c

@@ -12,7 +12,7 @@
 
 #define die() do { printf("Something went wrong!\n" \
     "Make sure you're running this program with administrator privileges\n"); \
-    sleep(10); exit(1); } while (0)
+    sleep(10); exit(EXIT_FAILURE); } while (0)
 
 #define MAX_FILTERS 4
 #define MAX_PACKET_SIZE 1516
@@ -23,21 +23,19 @@
     
 static HANDLE filters[MAX_FILTERS];
 static int filter_num = 0;
-static const char *http_redirect_10 = "HTTP/1.0 30";
-static const char *http_redirect_11 = "HTTP/1.1 30";
+static const char *http10_redirect_302 = "HTTP/1.0 302 ";
+static const char *http11_redirect_302 = "HTTP/1.1 302 ";
 static const char *http_host_find = "\r\nHost: ";
 static const char *http_host_replace = "\r\nhoSt: ";
-/*static const char *blocklist[] = {
-    "warning.rt.ru",
-};*/
+static const char *location_http = "\r\nLocation: http://";
 
-static char* dumb_memmem(char* haystack, int hlen, char* needle, int nlen) {
+static char* dumb_memmem(const char* haystack, int hlen, const char* needle, int nlen) {
     // naive implementation
     if (nlen > hlen) return 0;
     int i;
     for (i=0; i<hlen-nlen+1; i++) {
         if (memcmp(haystack+i,needle,nlen)==0) {
-            return haystack+i;
+            return (char*)(haystack+i);
         }
     }
     return NULL;
@@ -66,30 +64,37 @@ static void deinit_all() {
 
 static void sigint_handler(int sig) {
     deinit_all();
-    exit(0);
+    exit(EXIT_SUCCESS);
 }
 
-static int find_passivedpi_redirect(char *pktdata) {
-    if (memcmp(pktdata, http_redirect_11, strlen(http_redirect_11)) == 0
-        || memcmp(pktdata, http_redirect_10, strlen(http_redirect_10)) == 0) {
+static int is_passivedpi_redirect(const char *pktdata, int pktlen) {
+    /* First check if this is HTTP 302 redirect */
+    if (memcmp(pktdata, http11_redirect_302, strlen(http11_redirect_302)) == 0 ||
+        memcmp(pktdata, http10_redirect_302, strlen(http10_redirect_302)) == 0)
+    {
+        /* Then check if this is a redirect to new http site */
+        if (dumb_memmem(pktdata, pktlen, location_http, strlen(location_http))) {
             return 1;
         }
+    }
     return 0;
 }
 
 /* Finds Host header with \r\n before it */
-static PVOID find_host_header(char *pktdata, int pktlen) {
+static PVOID find_host_header(const char *pktdata, int pktlen) {
     return dumb_memmem(pktdata, pktlen,
-                (char*)http_host_find, strlen(http_host_find));
+                http_host_find, strlen(http_host_find));
 }
 
-static void change_window_size(char *pkt) {
-    *(pkt + IPV4_HDR_LEN + TCP_WINDOWSIZE_OFFSET) = 0x00;
-    *(pkt + IPV4_HDR_LEN + TCP_WINDOWSIZE_OFFSET + 1) = 0x02;
+static void change_window_size(char *pkt, int size) {
+    *(uint16_t*)(pkt + IPV4_HDR_LEN + TCP_WINDOWSIZE_OFFSET) = htons(size);
 }
 
 int main(int argc, char *argv[]) {
+    static const char fragment_size_message[] =
+                "Fragment size should be in range [0 - 65535]\n";
     int i, should_reinject = 0;
+    int opt;
     HANDLE w_filter = NULL;
     WINDIVERT_ADDRESS addr;
     char packet[MAX_PACKET_SIZE];
@@ -99,35 +104,88 @@ int main(int argc, char *argv[]) {
     PWINDIVERT_IPHDR ppIpHdr;
     PWINDIVERT_TCPHDR ppTcpHdr;
 
-    int do_passivedpi, do_fragment, do_host, do_host_removespace;
-    int temp;
-    char *data_addr, *data_addr_rn, *host_addr = NULL;
+    int do_passivedpi = 0, do_fragment_http = 0,
+        do_fragment_https = 0, do_host = 0,
+        do_host_removespace = 0;
+    int http_fragment_size = 2;
+    int https_fragment_size = 2;
+    char *data_addr, *data_addr_rn, *host_addr;
     int host_len, fromhost_uptoend_len;
 
-    printf("GoodbyeDPI: Passive DPI blocker and Active DPI circumvention utility\n\n");
+    printf("GoodbyeDPI: Passive DPI blocker and Active DPI circumvention utility\n");
 
-    if (argc == 2) {
-        temp = atoi(argv[1]);
-        do_passivedpi = !!(temp & 1);
-        do_fragment = !!(temp & 2);
-        do_host = !!(temp & 4);
-        do_host_removespace = !!(temp & 8);
-
-        printf("Block passive: %d, Fragment: %d, hoSt: %d, Host no space: %d\n",
-               do_passivedpi, do_fragment, do_host, do_host_removespace);
+    if (argc == 1) {
+        /* enable mode -1 by default */
+        do_passivedpi = do_host = do_host_removespace \
+            = do_fragment_http = do_fragment_https = 1;
     }
-    else {
-        printf("goodbyedpi.exe [1: block passive DPI, 2: fragment outbound, "
-               "4: replace Host with hoSt, 8: remove space between host header and value]\n");
-        printf("Default: 15 (all enabled)\n");
 
+    while ((opt = getopt(argc, argv, "1234prsf:e:")) != -1) {
+        switch (opt) {
+            case '1':
+                do_passivedpi = do_host = do_host_removespace \
+                = do_fragment_http = do_fragment_https = 1;
+                break;
+            case '2':
+                do_passivedpi = do_host = do_host_removespace \
+                = do_fragment_http = do_fragment_https = 1;
+                https_fragment_size = 40;
+                break;
+            case '3':
+                do_passivedpi = do_host = do_host_removespace \
+                = do_fragment_https = 1;
+                https_fragment_size = 40;
+            case '4':
+                do_passivedpi = do_host = do_host_removespace = 1;
+                break;
+            case 'p':
                 do_passivedpi = 1;
-        do_fragment = 1;
+                break;
+            case 'r':
                 do_host = 1;
+                break;
+            case 's':
                 do_host_removespace = 1;
+                break;
+            case 'f':
+                do_fragment_http = 1;
+                http_fragment_size = atoi(optarg);
+                if (http_fragment_size <= 0 || http_fragment_size > 65535) {
+                    printf(fragment_size_message);
+                    exit(EXIT_FAILURE);
+                }
+                break;
+            case 'e':
+                do_fragment_https = 1;
+                https_fragment_size = atoi(optarg);
+                if (https_fragment_size <= 0 || https_fragment_size > 65535) {
+                    printf(fragment_size_message);
+                    exit(EXIT_FAILURE);
+                }
+                break;
+            default:
+                printf("Usage: goodbyedpi.exe [OPTION...]\n"
+                " -p          block passive DPI\n"
+                " -r          replace Host with hoSt\n"
+                " -s          remove space between host header and its value\n"
+                " -f [value]  set HTTP fragmentation to value\n"
+                " -e [value]  set HTTPS fragmentation to value\n"
+                "\n"
+                " -1          enables all options, -f 2 -e 2 (most compatible mode, default)\n"
+                " -2          enables all options, -f 2 -e 40 (better speed yet still compatible)\n"
+                " -3          all options except HTTP fragmentation, -e 40 (even better speed)\n"
+                " -4          all options except fragmentation (best speed)\n");
+                exit(EXIT_FAILURE);
+        }
     }
 
-    printf("Opening filter\n");
+    printf("Block passive: %d, Fragment HTTP: %d, Fragment HTTPS: %d, "
+           "hoSt: %d, Host no space: %d\n",
+           do_passivedpi, (do_fragment_http ? http_fragment_size : 0),
+           (do_fragment_https ? https_fragment_size : 0),
+           do_host, do_host_removespace);
+
+    printf("\nOpening filter\n");
     filter_num = 0;
 
     if (do_passivedpi) {
@@ -173,28 +231,18 @@ int main(int argc, char *argv[]) {
                 if (addr.Direction == WINDIVERT_DIRECTION_INBOUND && packet_dataLen > 16) {
                     /* If INBOUND packet with DATA (tcp.Ack) */
 
-                    /* Drop packets from blocklist */
-                    /* for (i = 0; i < sizeof(blocklist) / sizeof(*blocklist); i++) {
-                        if (dumb_memmem(packet_data, packet_dataLen, (char*)blocklist[i],
-                            strlen(blocklist[i])) != NULL) {
-                                printf("Dropping packet!\n");
-                                dropped = 1;
-                                break;
-                        }
-                    } */
-
                     /* Drop packets from filter with HTTP 30x Redirect */
-                    if (do_passivedpi && find_passivedpi_redirect(packet_data)) {
+                    if (do_passivedpi && is_passivedpi_redirect(packet_data, packet_dataLen)) {
                         //printf("Dropping HTTP Redirect packet!\n");
                         should_reinject = 0;
                     }
                 }
                 /* Handle OUTBOUND packet, search for Host header */
                 else if (addr.Direction == WINDIVERT_DIRECTION_OUTBOUND && 
-                         packet_dataLen > 16 && ppTcpHdr->DstPort == htons(80)) {
-                    if (do_host || do_host_removespace) {
+                         packet_dataLen > 16 && ppTcpHdr->DstPort == htons(80) &&
+                        (do_host || do_host_removespace)) {
+
                     data_addr = find_host_header(packet_data, packet_dataLen);
-                    }
 
                     if (do_host && data_addr) {
                         /* Replace "Host: " with "hoSt: " */
@@ -205,12 +253,12 @@ int main(int argc, char *argv[]) {
                     if (do_host_removespace && data_addr) {
                         host_addr = data_addr + strlen(http_host_find);
 
+                        fromhost_uptoend_len = packet_dataLen - ((PVOID)host_addr - packet_data);
                         data_addr_rn = dumb_memmem(host_addr,
-                                                    packet_dataLen - ((PVOID)host_addr - packet_data),
+                                                    fromhost_uptoend_len,
                                                     "\r\n", 2);
                         if (data_addr_rn) {
                             host_len = data_addr_rn - host_addr;
-                            fromhost_uptoend_len = packet_dataLen - ((PVOID)host_addr - packet_data);
                             if (host_len <= 64) {
                                 /* Move memory left by 1 byte and reduce packet size for 1 byte */
                                 memmove(host_addr - 1, host_addr, fromhost_uptoend_len);
@@ -223,20 +271,22 @@ int main(int argc, char *argv[]) {
                             }
                         }
                     }
-                    if (do_host || do_host_removespace) {
                     WinDivertHelperCalcChecksums(packet, packetLen, 0);
                 }
             }
-            }
             /* Else if we got TCP packet without data */
             else if (WinDivertHelperParsePacket(packet, packetLen, &ppIpHdr,
                 NULL, NULL, NULL, &ppTcpHdr, NULL, NULL, NULL)) {
                 /* If we got SYN+ACK packet */
                 if (addr.Direction == WINDIVERT_DIRECTION_INBOUND && 
                     ppTcpHdr->Syn == 1) {
-                    if (do_fragment) {
                     //printf("Changing Window Size!\n");
-                        change_window_size(packet);
+                    if (do_fragment_http && ppTcpHdr->DstPort == htons(80)) {
+                        change_window_size(packet, http_fragment_size);
+                        WinDivertHelperCalcChecksums(packet, packetLen, 0);
+                    }
+                    else if (do_fragment_https && ppTcpHdr->DstPort != htons(80)) {
+                        change_window_size(packet, https_fragment_size);
                         WinDivertHelperCalcChecksums(packet, packetLen, 0);
                     }
                 }