Merge pull request #666 from dumprop/master

Apply #616 fix to flows.c, fix #665
appneta · Jun 19, 2021 · 9f6f3d5 · 9f6f3d5
2 parents d55aaba + df35d58
commit 9f6f3d5
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Showing 2 changed files with 13 additions and 11 deletions.
diff --git a/src/common/flows.c b/src/common/flows.c
@@ -23,6 +23,10 @@
 #include <string.h>
 #include "../../lib/sll.h"
 
+#define JUNIPER_FLAG_NO_L2          0x02     /* L2 header */
+#define JUNIPER_FLAG_EXT            0x80     /* Juniper extensions present */
+#define JUNIPER_PCAP_MAGIC          "MGC"
+
 /* 5-tuple plus VLAN ID */
 typedef struct flow_entry_data {
     union {
@@ -220,21 +224,22 @@ flow_entry_type_t flow_decode(flow_hash_table_t *fht, const struct pcap_pkthdr *
         break;
 
     case DLT_JUNIPER_ETHER:
-        if (pkthdr->caplen < 5)
+        if (pkthdr->caplen < 4)
             return FLOW_ENTRY_INVALID;
 
-        if (memcmp(pktdata, "MGC", 3))
+        if (memcmp(pktdata, JUNIPER_PCAP_MAGIC, 3)){
             warnx("No Magic Number found: %s (0x%x)",
-                 pcap_datalink_val_to_description(datalink), datalink);
+                  pcap_datalink_val_to_description(datalink), datalink);
+            return 0;
+        }
 
-        if ((pktdata[3] & 0x80) == 0x80) {
+        if ((pktdata[3] & JUNIPER_FLAG_EXT) == JUNIPER_FLAG_EXT) {
             l2_len = ntohs(*((uint16_t*)&pktdata[4]));
-            l2_len += 6;
+            l2_len += 6; /* MGC + flags + ext_total_len */
         } else {
-            l2_len = 4; /* no header extensions */
+            l2_len = 4; /* MGC + flags (no header extensions) */
         }
-
-        /* fallthrough */
+        /* fall through */
     case DLT_EN10MB:
         /* l2_len will be zero if we did not fall through */
         if (pkthdr->caplen < l2_len + sizeof(eth_hdr_t))

diff --git a/src/common/get.c b/src/common/get.c
@@ -109,9 +109,6 @@ get_l2protocol(const u_char *pktdata, const uint32_t datalen, const int datalink
         }
 
         if ((pktdata[3] & JUNIPER_FLAG_EXT) == JUNIPER_FLAG_EXT) {
-            if (datalen < 6)
-                return 0;  /* datalen too short */
-
             eth_hdr_offset = ntohs(*((uint16_t*)&pktdata[4]));
             eth_hdr_offset += 6; /* MGC + flags + ext_total_len */
         } else {