#include "openflow.h"
#include "oui.h"
-static const char tstr[] = " [|openflow]";
#define OF_VER_1_0 0x01
version, type, length, xid);
}
-/* Print a single OpenFlow message. */
-static const u_char *
-of_header_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
-{
- uint8_t version, type;
- uint16_t length;
- uint32_t xid;
-
- if (ep < cp + OF_HEADER_LEN)
- goto invalid;
- /* version */
- ND_TCHECK_1(cp);
- version = EXTRACT_U_1(cp);
- cp += 1;
- /* type */
- ND_TCHECK_1(cp);
- type = EXTRACT_U_1(cp);
- cp += 1;
- /* length */
- ND_TCHECK_2(cp);
- length = EXTRACT_BE_U_2(cp);
- cp += 2;
- /* xid */
- ND_TCHECK_4(cp);
- xid = EXTRACT_BE_U_4(cp);
- cp += 4;
- /* Message length includes the header length and a message always includes
- * the basic header. A message length underrun fails decoding of the rest of
- * the current packet. At the same time, try decoding as much of the current
- * message as possible even when it does not end within the current TCP
- * segment. */
- if (length < OF_HEADER_LEN) {
- of_header_print(ndo, version, type, length, xid);
- goto invalid;
- }
- /* Decode known protocol versions further without printing the header (the
- * type decoding is version-specific. */
- switch (version) {
- case OF_VER_1_0:
- return of10_header_body_print(ndo, cp, ep, type, length, xid);
- default:
- of_header_print(ndo, version, type, length, xid);
- ND_TCHECK_LEN(cp, length - OF_HEADER_LEN);
- return cp + length - OF_HEADER_LEN; /* done with current message */
- }
-
-invalid: /* fail current packet */
- ND_PRINT("%s", istr);
- ND_TCHECK_LEN(cp, ep - cp);
- return ep;
-trunc:
- ND_PRINT("%s", tstr);
- return ep;
-}
-
/* Print a TCP segment worth of OpenFlow messages presuming the segment begins
* on a message boundary. */
void
-openflow_print(netdissect_options *ndo, const u_char *cp, const u_int len _U_)
+openflow_print(netdissect_options *ndo, const u_char *cp, u_int len)
{
ndo->ndo_protocol = "openflow";
ND_PRINT(": OpenFlow");
- while (cp < ndo->ndo_snapend)
- cp = of_header_body_print(ndo, cp, ndo->ndo_snapend);
+ while (len) {
+ /* Print a single OpenFlow message. */
+ uint8_t version, type;
+ uint16_t length;
+ uint32_t xid;
+
+ if (len < OF_HEADER_FIXLEN)
+ goto invalid;
+ /* version */
+ version = GET_U_1(cp);
+ OF_FWD(1);
+ /* type */
+ type = GET_U_1(cp);
+ OF_FWD(1);
+ /* length */
+ length = GET_BE_U_2(cp);
+ OF_FWD(2);
+ /* xid */
+ xid = GET_BE_U_4(cp);
+ OF_FWD(4);
+ /*
+ * When a TCP packet can contain several protocol messages,
+ * and at the same time a protocol message can span several
+ * TCP packets, decoding an incomplete message at the end of
+ * a TCP packet requires attention to detail in this loop.
+ *
+ * Message length includes the header length and a message
+ * always includes the basic header. A message length underrun
+ * fails decoding of the rest of the current packet. At the
+ * same time, try decoding as much of the current message as
+ * possible even when it does not end within the current TCP
+ * segment.
+ *
+ * Specifically, to try to process the message body in this
+ * iteration do NOT require the header "length" to be small
+ * enough for the full declared OpenFlow message to fit into
+ * the remainder of the declared TCP segment, same as the full
+ * declared TCP segment is not required to fit into the
+ * captured packet buffer.
+ *
+ * But DO require the same at the end of this iteration to
+ * decrement "len" and to proceed to the next iteration.
+ * (Ideally the declared TCP payload end will be at or after
+ * the captured packet buffer end, but stay safe even when
+ * that's somehow not the case.)
+ */
+ if (length < OF_HEADER_FIXLEN) {
+ of_header_print(ndo, version, type, length, xid);
+ goto invalid;
+ }
+ /*
+ * Decode known protocol versions further without printing the
+ * header (the type decoding is version-specific).
+ */
+ switch (version) {
+ case OF_VER_1_0:
+ of10_header_body_print(ndo, cp, type,
+ length - OF_HEADER_FIXLEN, xid);
+ break;
+ default:
+ of_header_print(ndo, version, type, length, xid);
+ ND_TCHECK_LEN(cp, length - OF_HEADER_FIXLEN);
+ }
+ if (length - OF_HEADER_FIXLEN > len)
+ break;
+ OF_FWD(length - OF_HEADER_FIXLEN);
+ } /* while (len) */
+ return;
+
+invalid: /* fail the current packet */
+ nd_print_invalid(ndo);
+ ND_TCHECK_LEN(cp, len);
+ return;
+trunc:
+ nd_trunc(ndo);
}
projects / tcpdump / blobdiff