From 24cc949f1405b0d9e0be26848168fd3df52bf6d3 Mon Sep 17 00:00:00 2001
From: Luca Deri <deri@ntop.org>
Date: Sat, 22 Oct 2022 10:06:09 +0200
Subject: Enhanced HTTP numeric IP check

---
 src/include/ndpi_main.h  |  2 +-
 src/lib/ndpi_utils.c     | 29 +++++++++++++++++++++++++++++
 src/lib/protocols/http.c | 18 ++++++++++++++++--
 3 files changed, 46 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/include/ndpi_main.h b/src/include/ndpi_main.h
index 4e7284748..ce3439279 100644
--- a/src/include/ndpi_main.h
+++ b/src/include/ndpi_main.h
@@ -171,7 +171,7 @@ extern "C" {
   char *ndpi_user_agent_set(struct ndpi_flow_struct *flow, const u_int8_t *value, size_t value_len);
 
   int64_t ndpi_asn1_ber_decode_length(const unsigned char *payload, int payload_len, u_int16_t *value_len);
-
+  char* ndpi_intoav4(unsigned int addr, char* buf, u_int16_t bufLen);
   int ndpi_current_pkt_from_client_to_server(const struct ndpi_packet_struct *packet, const struct ndpi_flow_struct *flow);
   int ndpi_current_pkt_from_server_to_client(const struct ndpi_packet_struct *packet, const struct ndpi_flow_struct *flow);
   int ndpi_seen_flow_beginning(const struct ndpi_flow_struct *flow);
diff --git a/src/lib/ndpi_utils.c b/src/lib/ndpi_utils.c
index ef212cc5f..255a1fa8e 100644
--- a/src/lib/ndpi_utils.c
+++ b/src/lib/ndpi_utils.c
@@ -2835,3 +2835,32 @@ int64_t ndpi_asn1_ber_decode_length(const unsigned char *payload, int payload_le
   (*value_len) += 1;
   return value;
 }
+
+/* ******************************************* */
+
+char* ndpi_intoav4(unsigned int addr, char* buf, u_int16_t bufLen) {
+  char *cp;
+  int n;
+
+  cp = &buf[bufLen];
+  *--cp = '\0';
+
+  n = 4;
+  do {
+    u_int byte = addr & 0xff;
+
+    *--cp = byte % 10 + '0';
+    byte /= 10;
+    if(byte > 0) {
+      *--cp = byte % 10 + '0';
+      byte /= 10;
+      if(byte > 0)
+	*--cp = byte + '0';
+    }
+    if(n > 1)
+      *--cp = '.';
+    addr >>= 8;
+  } while (--n > 0);
+
+  return(cp);
+}
diff --git a/src/lib/protocols/http.c b/src/lib/protocols/http.c
index 7e6ae2d28..a7876c15e 100644
--- a/src/lib/protocols/http.c
+++ b/src/lib/protocols/http.c
@@ -395,14 +395,28 @@ static void setHttpUserAgent(struct ndpi_detection_module_struct *ndpi_struct,
 /* ************************************************************* */
 
 static void ndpi_http_parse_subprotocol(struct ndpi_detection_module_struct *ndpi_struct,
-				 struct ndpi_flow_struct *flow) {
+					struct ndpi_flow_struct *flow) {
   u_int16_t master_protocol;
 
   if((flow->l4.tcp.http_stage == 0) || (flow->http.url && flow->http_detected)) {
     char *double_col = strchr((char*)flow->host_server_name, ':');
-
+    int a, b, c, d;
+    
     if(double_col) double_col[0] = '\0';
 
+    if(ndpi_struct->packet.iph
+       && (sscanf(flow->host_server_name, "%d.%d.%d.%d", &a, &b, &c, &d) == 4)) {
+      /* IPv4 */
+
+      if(ndpi_struct->packet.iph->daddr != inet_addr(flow->host_server_name)) {
+	char buf[64], msg[128];
+	
+	snprintf(msg, sizeof(msg), "Expected %s, found %s",
+		 ndpi_intoav4(ntohl(ndpi_struct->packet.iph->daddr), buf, sizeof(buf)), flow->host_server_name);
+	ndpi_set_risk(ndpi_struct, flow, NDPI_HTTP_SUSPICIOUS_HEADER, msg);
+      }
+    }
+    
     master_protocol = NDPI_PROTOCOL_HTTP;
     if(flow->detected_protocol_stack[1] != NDPI_PROTOCOL_UNKNOWN)
       master_protocol = flow->detected_protocol_stack[1];
-- 
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