Replace char* with const char* where appropriate

goodbyedpi.c

@@ -23,18 +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 *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;
@@ -66,18 +67,23 @@ static void sigint_handler(int sig) {
     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, int size) {
@@ -114,7 +120,7 @@ int main(int argc, char *argv[]) {
             = do_fragment_http = do_fragment_https = 1;
     }
 
-    while ((opt = getopt(argc, argv, "123prsf:e:")) != -1) {
+    while ((opt = getopt(argc, argv, "1234prsf:e:")) != -1) {
         switch (opt) {
             case '1':
                 do_passivedpi = do_host = do_host_removespace \
@@ -226,7 +232,7 @@ int main(int argc, char *argv[]) {
                     /* If INBOUND packet with DATA (tcp.Ack) */
 
                     /* 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;
                     }