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Less invasive Passive DPI block. Fix #2.

This commit is contained in:
ValdikSS 2017-05-20 12:24:29 +03:00
parent bb05d357a7
commit 9fea771d2c
1 changed files with 13 additions and 7 deletions
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20
goodbyedpi.c
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@ -23,10 +23,11 @@
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) {
// naive implementation
@ -66,10 +67,15 @@ 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) {
return 1;
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;
}
@ -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;
}