macsec: further cleanups.

[tcpdump] / print-macsec.c

diff --git a/print-macsec.c b/print-macsec.c
index 757d6ed486a547174811ebb586006ebbd6caef92..a7bde0b959f2a7129c6c523fef554cebd4039636 100644 (file)
--- a/print-macsec.c
+++ b/print-macsec.c
@@ -34,8 +34,6 @@
 #include "ethertype.h"
 #include "extract.h"
 
-static const char tstr[] = "[|MACsec]";
-
 #define MACSEC_DEFAULT_ICV_LEN 16
 
 /* Header format (SecTAG), following an Ethernet header
@@ -77,40 +75,8 @@ struct macsec_sectag {
 #define MACSEC_TCI_CONFID  (MACSEC_TCI_E | MACSEC_TCI_C)
 #define MACSEC_SL_MASK     0x3F /* short length */
 
-#define MACSEC_SECTAG_LEN_NOSCI 6
-#define MACSEC_SECTAG_LEN_SCI 14
-static int
-ieee8021ae_sectag_len(netdissect_options *ndo, const struct macsec_sectag *sectag)
-{
-       return (GET_U_1(sectag->tci_an) & MACSEC_TCI_SC) ?
-              MACSEC_SECTAG_LEN_SCI :
-              MACSEC_SECTAG_LEN_NOSCI;
-}
-
-static int macsec_check_length(netdissect_options *ndo, const struct macsec_sectag *sectag, u_int length, u_int caplen)
-{
-       u_int len;
-
-       /* we need the full MACsec header in the capture */
-       if (caplen < (MACSEC_SECTAG_LEN_NOSCI + 2))
-               return 0;
-
-       len = ieee8021ae_sectag_len(ndo, sectag);
-       if (caplen < (len + 2))
-               return 0;
-
-       if ((GET_U_1(sectag->short_length) & MACSEC_SL_MASK) != 0) {
-               /* original packet must have exact length */
-               u_int exact = ETHER_HDRLEN + len + 2 + (GET_U_1(sectag->short_length) & MACSEC_SL_MASK);
-               return exact == length;
-       } else {
-               /* original packet must not be short */
-               u_int minlen = ETHER_HDRLEN + len + 2 + 48;
-               return length >= minlen;
-       }
-
-       return 1;
-}
+#define MACSEC_SECTAG_LEN_NOSCI 6  /* length of MACsec header without SCI */
+#define MACSEC_SECTAG_LEN_SCI   14 /* length of MACsec header with SCI */
 
 #define SCI_FMT "%016" PRIx64
 
@@ -125,24 +91,50 @@ static const struct tok macsec_flag_values[] = {
 
 /* returns < 0 iff the packet can be decoded completely */
 int macsec_print(netdissect_options *ndo, const u_char **bp,
-                u_int *lengthp, u_int *caplenp, u_int *hdrlenp,
-                u_short *length_type)
+                u_int *lengthp, u_int *caplenp, u_int *hdrlenp)
 {
+       const char *save_protocol;
        const u_char *p = *bp;
        u_int length = *lengthp;
        u_int caplen = *caplenp;
        u_int hdrlen = *hdrlenp;
        const struct macsec_sectag *sectag = (const struct macsec_sectag *)p;
-       u_int len;
+       u_int sectag_len;
 
-       if (!macsec_check_length(sectag, length, caplen)) {
+       save_protocol = ndo->ndo_protocol;
+       ndo->ndo_protocol = "MACsec";
+
+       /* we need the full MACsec header in the capture */
+       if (caplen < MACSEC_SECTAG_LEN_NOSCI) {
+               nd_print_trunc(ndo);
+               ndo->ndo_protocol = save_protocol;
+               return hdrlen + caplen;
+       }
+       if (length < MACSEC_SECTAG_LEN_NOSCI) {
                nd_print_trunc(ndo);
+               ndo->ndo_protocol = save_protocol;
                return hdrlen + caplen;
        }
 
+       if (GET_U_1(sectag->tci_an) & MACSEC_TCI_SC) {
+               sectag_len = MACSEC_SECTAG_LEN_SCI;
+               if (caplen < MACSEC_SECTAG_LEN_SCI) {
+                       nd_print_trunc(ndo);
+                       ndo->ndo_protocol = save_protocol;
+                       return hdrlen + caplen;
+               }
+               if (length < MACSEC_SECTAG_LEN_SCI) {
+                       nd_print_trunc(ndo);
+                       ndo->ndo_protocol = save_protocol;
+                       return hdrlen + caplen;
+               }
+       } else
+               sectag_len = MACSEC_SECTAG_LEN_NOSCI;
+
        if ((GET_U_1(sectag->short_length) & ~MACSEC_SL_MASK) != 0 || 
            GET_U_1(sectag->tci_an) & MACSEC_TCI_VERSION) {
                nd_print_invalid(ndo);
+               ndo->ndo_protocol = save_protocol;
                return hdrlen + caplen;
        }
 
@@ -162,26 +154,32 @@ int macsec_print(netdissect_options *ndo, const u_char **bp,
                ND_PRINT(", ");
        }
 
-       len = ieee8021ae_sectag_len(ndo, sectag);
-       *length_type = GET_BE_U_2(*bp + len);
-       if (ndo->ndo_eflag && *length_type > ETHERMTU && !(GET_U_1(sectag->tci_an) & MACSEC_TCI_E))
-               ND_PRINT("ethertype %s, ", tok2str(ethertype_values,"0x%04x", *length_type));
+       /* Skip the MACsec header. */
+       *bp += sectag_len;
+       *hdrlenp += sectag_len;
 
-       if ((GET_U_1(sectag->tci_an) & MACSEC_TCI_CONFID)) {
-               *bp += len;
-               *hdrlenp += len;
+       /* Remove it from the lengths, as it's been processed. */
+       *lengthp -= sectag_len;
+       *caplenp -= sectag_len;
 
-               *lengthp -= len;
-               *caplenp -= len;
+       if ((GET_U_1(sectag->tci_an) & MACSEC_TCI_CONFID)) {
+               /*
+                * The payload is encrypted.  Tell our
+                * caller it can't be dissected.
+                */
+               ndo->ndo_protocol = save_protocol;
                return 0;
        } else {
-               len += 2;
-               *bp += len;
-               *hdrlenp += len;
-
-               len += MACSEC_DEFAULT_ICV_LEN;
-               *lengthp -= len;
-               *caplenp -= len;
+               /*
+                * The payload isn't encrypted; remove the
+                * ICV length from the lengths, so our caller
+                * doesn't treat it as payload.
+                */
+               if (*lengthp >= MACSEC_DEFAULT_ICV_LEN)
+                       *lengthp -= MACSEC_DEFAULT_ICV_LEN;
+               if (*caplenp >= MACSEC_DEFAULT_ICV_LEN)
+                       *caplenp -= MACSEC_DEFAULT_ICV_LEN;
+               ndo->ndo_protocol = save_protocol;
                return -1;
        }
 }