Changeset 692bf9c

Timestamp:

02/05/19 09:41:34 (2 years ago)

Author:

Jacob Van Walraven <jcv9@…>

Branches:

develop

Children:

db919d5

Parents:

1668208

Message:

Add support to retrieve outermost vlan tag, outermost mpls label, and all layer2 headers

Location:

lib

Files:

• libtrace.h.in (modified) (4 diffs)
• protocols_l2.c (modified) (1 diff)

lib/libtrace.h.in

@@ -346 +346 @@
         /** NULL passed misc **/
         TRACE_ERR_NULL = -31,
+        /** ERR out of memory **/
+        TRACE_ERR_OUT_OF_MEMORY = -33,
 };
 
@@ -570 +572 @@
         TRACE_ETHERTYPE_RARP    = 0x8035,       /**< Reverse ARP */
         TRACE_ETHERTYPE_8021Q   = 0x8100,       /**< 802.1q VLAN Extended Header */
+        TRACE_ETHERTYPE_8021QS  = 0x88A8,       /**< 802.1q Service VLAN tag */
         TRACE_ETHERTYPE_IPV6    = 0x86DD,       /**< IPv6 */
         TRACE_ETHERTYPE_MPLS    = 0x8847,       /**< MPLS Unicast traffic */
@@ -576 +579 @@
         TRACE_ETHERTYPE_PPP_SES = 0x8864        /**< PPPoE Session Messages */
 } libtrace_ethertype_t;
+
+/** constant to check if a vlan was found */
+#define VLAN_NOT_FOUND 0xFF
+
+/** constant to check if a mpls label was found */
+#define MPLS_NOT_FOUND 0xFFFF
+
+typedef struct libtrace_layer2_header {
+        uint16_t ethertype;                     /**< Ethertype of the header */
+        void *data;                             /**< Pointer to the header */
+} libtrace_layer2_header_t;
+typedef struct libtrace_layer2_headers {
+        uint64_t bitmask;                       /**< Bitmask of found headers */
+        int num;                                /**< The number of header */
+        libtrace_layer2_header_t *header;       /**< Array of all found layer2 headers */
+} libtrace_layer2_headers_t;
+/** Enumeration of bitmask layer2 headers within libtrace_layer2_headers_t */
+enum {
+        TRACE_BITMASK_LOOPBACK  = 1,
+        TRACE_BITMASK_IP        = 2,
+        TRACE_BITMASK_ARP       = 4,
+        TRACE_BITMASK_RARP      = 8,
+        TRACE_BITMASK_8021Q     = 16,
+        TRACE_BITMASK_IPV6      = 32,
+        TRACE_BITMASK_8021QS    = 64,
+        TRACE_BITMASK_MPLS      = 128,
+        TRACE_BITMASK_MPLS_MC   = 256,
+        TRACE_BITMASK_PPP_DISC  = 512,
+        TRACE_BITMASK_PPP_SES   = 1024,
+};
 
 typedef struct libtrace_packet_cache {
@@ -2411 +2444 @@
                 void *vlan, uint16_t *type, uint32_t *remaining);
 
+/** Get the outermost VLAN ID from a packet.
+ * @param packet                A pointer to the packet
+ * @param[out] vlanptr          A pointer to the VLAN header
+ * @param[out] remaining        Updated with the number of captured bytes remaining
+ *
+ * @return The outermost VLAN id if found or VLAN_NOT_FOUND
+ *
+ * vlanptr will be set to the start of the VLAN header found (or NULL if no
+ * VLAN tags are present).
+ *
+ * remaining will be set to the number of captured bytes in the packet,
+ * starting from the returned VLAN header.
+ */
+DLLEXPORT uint16_t trace_get_outermost_vlan(
+        libtrace_packet_t *packet, uint8_t **vlanptr, uint32_t *remaining);
+
+/** Get all layer2 headers from a packet.
+ * @param packet        A pointer to the packet
+ *
+ * @return A libtrace_layer2_headers_t structure containing all found layer2
+ * headers (or NULL if no layer2 headers are found). This structure must be
+ * destroyed with trace_destroy_layer2_headers().
+ */
+DLLEXPORT libtrace_layer2_headers_t *trace_get_layer2_headers(libtrace_packet_t *packet);
+
+/** Destroys a libtrace_layer2_headers_t structure.
+ * @param headers       A pointer to the libtrace_layer2_headers_t structure
+ *
+ * @returns 1 on successful deletion.
+ */
+DLLEXPORT int trace_destroy_layer2_headers(libtrace_layer2_headers_t *headers);
+
+/** Get the outermost MPLS label from a packet.
+ * @param packet                A pointer to the packet
+ * @param[out] mplsptr          A pointer to the mpls header
+ * @param[out] remaining        Updated with the number of captured bytes remaining
+ *
+ * @return The outmost MPLS label if found or MPLS_NOT_FOUND
+ *
+ * mplsptr will be set to the start of the MPLS header (or NULL if no
+ * MPLS header is found)
+ *
+ * remaining will be set to the number of captured bytes in the packet,
+ * starting from the MPLS header.
+ */
+DLLEXPORT uint32_t trace_get_outermost_mpls(
+        libtrace_packet_t *packet, uint8_t **mplsptr, uint32_t *remaining);
+
 /** Gets a pointer to the payload following an MPLS header.
  * @param mpls      A pointer to the MPLS header

lib/protocols_l2.c

@@ -90 +90 @@
         return (void*)((char *)ethernet + sizeof(*vlanhdr));
 
+}
+
+int trace_destroy_layer2_headers(libtrace_layer2_headers_t *headers) {
+        if (headers == NULL) {
+                fprintf(stderr, "NULL libtrace_layer2_headers_t passed into "
+                        "trace_destroy_layer2_headers()\n");
+                return -1;
+        }
+
+        if (headers->header != NULL) {
+                free(headers->header);
+        }
+        free(headers);
+        return 1;
+}
+libtrace_layer2_headers_t *trace_get_layer2_headers(libtrace_packet_t *packet) {
+
+        char *ptr;
+        libtrace_linktype_t linktype;
+        uint32_t remaining;
+        uint16_t ethertype;
+        libtrace_layer2_headers_t *r;
+
+        if (packet == NULL) {
+                fprintf(stderr, "NULL packet passed into trace_get_layer2_headers()\n");
+                return NULL;
+        }
+        if (packet->trace == NULL) {
+                fprintf(stderr, "Packet contains a NULL trace in trace_get_layer2_headers()\n");
+                return NULL;
+        }
+
+        /* jump to layer 2 */
+        ptr = trace_get_layer2(packet, &linktype, &remaining);
+        /* packet does not contain layer2 */
+        if (ptr == NULL) {
+                return NULL;
+        }
+
+        /* allocate memory for the result */
+        r = calloc(1, sizeof(libtrace_layer2_headers_t));
+        if (r == NULL) {
+                trace_set_err(packet->trace, TRACE_ERR_OUT_OF_MEMORY,
+                        "Unable to allocate memory in trace_get_layer2_headers()\n");
+                return NULL;
+        }
+        r->header = calloc(1, sizeof(libtrace_layer2_header_t));
+        if (r->header == NULL) {
+                trace_set_err(packet->trace, TRACE_ERR_OUT_OF_MEMORY,
+                        "Unable to allocate memory in trace_get_layer2_headers()\n");
+                free(r);
+                return NULL;
+        }
+
+        /* get the first layer2 header */
+        ptr = trace_get_payload_from_layer2(ptr, linktype, &ethertype, &remaining);
+
+        while (remaining != 0 && ptr != NULL) {
+
+                if (ethertype == TRACE_ETHERTYPE_LOOPBACK ||
+                        ethertype == TRACE_ETHERTYPE_IP ||
+                        ethertype == TRACE_ETHERTYPE_ARP ||
+                        ethertype == TRACE_ETHERTYPE_RARP ||
+                        ethertype == TRACE_ETHERTYPE_8021Q ||
+                        ethertype == TRACE_ETHERTYPE_IPV6 ||
+                        ethertype == TRACE_ETHERTYPE_8021QS ||
+                        ethertype == TRACE_ETHERTYPE_MPLS ||
+                        ethertype == TRACE_ETHERTYPE_MPLS_MC ||
+                        ethertype == TRACE_ETHERTYPE_PPP_DISC ||
+                        ethertype == TRACE_ETHERTYPE_PPP_SES) {
+
+                        /* Set the bitmask */
+                        switch (ethertype) {
+                                case (TRACE_ETHERTYPE_LOOPBACK):
+                                        r->bitmask |= TRACE_BITMASK_LOOPBACK;
+                                        break;
+                                case (TRACE_ETHERTYPE_IP):
+                                        r->bitmask |= TRACE_BITMASK_IP;
+                                        break;
+                                case (TRACE_ETHERTYPE_ARP):
+                                        r->bitmask |= TRACE_BITMASK_ARP;
+                                        break;
+                                case (TRACE_ETHERTYPE_RARP):
+                                        r->bitmask |= TRACE_BITMASK_RARP;
+                                        break;
+                                case (TRACE_ETHERTYPE_8021Q):
+                                        r->bitmask |= TRACE_BITMASK_8021Q;
+                                        break;
+                                case (TRACE_ETHERTYPE_IPV6):
+                                        r->bitmask |= TRACE_BITMASK_IPV6;
+                                        break;
+                                case (TRACE_ETHERTYPE_8021QS):
+                                        r->bitmask |= TRACE_BITMASK_8021QS;
+                                        break;
+                                case (TRACE_ETHERTYPE_MPLS):
+                                        r->bitmask |= TRACE_BITMASK_MPLS;
+                                        break;
+                                case (TRACE_ETHERTYPE_MPLS_MC):
+                                        r->bitmask |= TRACE_BITMASK_MPLS_MC;
+                                        break;
+                                case (TRACE_ETHERTYPE_PPP_DISC):
+                                        r->bitmask |= TRACE_BITMASK_PPP_DISC;
+                                        break;
+                                case (TRACE_ETHERTYPE_PPP_SES):
+                                        r->bitmask |= TRACE_BITMASK_PPP_SES;
+                                        break;
+                        }
+
+                        r->header = realloc(r->header,
+                                sizeof(libtrace_layer2_header_t)*(r->num+1));
+                        r->header[r->num].ethertype = ethertype;
+                        r->header[r->num++].data = ptr;
+                }
+
+                /* if the last ethertype was IP stop */
+                if (ethertype == TRACE_ETHERTYPE_IP || ethertype == TRACE_ETHERTYPE_IPV6) {
+                        break;
+                }
+
+                /* get the next header */
+                ptr = trace_get_payload_from_layer2(ptr, linktype, &ethertype, &remaining);
+        }
+
+        /* If no results were found free memory now and just return NULL */
+        if (r->num) {
+                free(r->header);
+                free(r);
+                return NULL;
+        }
+
+        return r;
+}
+
+uint16_t trace_get_outermost_vlan(libtrace_packet_t *packet, uint8_t **vlanptr,
+        uint32_t *remaining) {
+
+        uint8_t *ptr;
+        libtrace_linktype_t linktype;
+        uint32_t rem;
+        uint16_t vlanid = VLAN_NOT_FOUND;
+        uint16_t ethertype = 0;
+
+        if (!packet) {
+                fprintf(stderr, "NULL packet passed into trace_get_outermost_vlan()\n");
+                *vlanptr = NULL;
+                *remaining = rem;
+                return vlanid;
+        }
+
+        ptr = trace_get_layer2(packet, &linktype, &rem);
+        /* No layer 2 */
+        if (ptr == NULL) {
+                *vlanptr = NULL;
+                        *remaining = rem;
+                return vlanid;
+        }
+
+        while (ethertype != TRACE_ETHERTYPE_8021Q && ethertype != TRACE_ETHERTYPE_8021QS) {
+
+                if (rem == 0 || ptr == NULL || ethertype == TRACE_ETHERTYPE_IP ||
+                        ethertype == TRACE_ETHERTYPE_IPV6) {
+
+                        *vlanptr = NULL;
+                        *remaining = rem;
+                        return vlanid;
+                }
+
+                /* get the next layer 2 header */
+                ptr = trace_get_payload_from_layer2(ptr, linktype, &ethertype, &rem);
+        }
+
+        /* found a vlan header */
+        uint32_t val = ntohl(*(uint32_t *)ptr);
+        /* the id portion is only 12 bits */
+        vlanid = (((val >> 16) << 4) >> 4);
+
+        *remaining = rem;
+        *vlanptr = ptr;
+        return vlanid;
+}
+
+uint32_t trace_get_outermost_mpls(libtrace_packet_t *packet, uint8_t **mplsptr,
+        uint32_t *remaining) {
+
+        uint8_t *ptr;
+        uint32_t mplslabel = MPLS_NOT_FOUND;
+        libtrace_linktype_t linktype;
+        uint32_t rem;
+        uint16_t ethertype = 0;
+
+        if (!packet) {
+                fprintf(stderr, "NULL packet passed into trace_get_outermost_mpls()\n");
+                *remaining = 0;
+                *mplsptr = NULL;
+                return mplslabel;
+        }
+
+        ptr = trace_get_layer2(packet, &linktype, &rem);
+        /* No layer2 */
+        if (ptr == NULL) {
+                *remaining = rem;
+                *mplsptr = NULL;
+                return mplslabel;
+        }
+
+        /* loop over the packet until we find a mpls label */
+        while (ethertype != TRACE_ETHERTYPE_MPLS) {
+                if (rem == 0 || ptr == NULL) {
+
+                        *remaining = rem;
+                        *mplsptr = NULL;
+                        return mplslabel;
+                }
+
+                /* get next layer2 header */
+                ptr = trace_get_payload_from_layer2(ptr, linktype, &ethertype, &rem);
+        }
+
+        uint32_t val = ntohl(*(uint32_t *)ptr);
+        mplslabel = val >> 12;
+
+        *remaining = rem;
+        *mplsptr = ptr;
+        return mplslabel;
 }