Changeset 7fc0eaa2 for lib

Timestamp:

03/15/10 16:58:28 (12 years ago)

Author:

Shane Alcock <salcock@…>

Branches:

4.0.1-hotfixes, cachetimestamps, develop, dpdk-ndag, etsilive, getfragoff, help, libtrace4, master, ndag_format, pfring, rc-4.0.1, rc-4.0.2, rc-4.0.3, rc-4.0.4, ringdecrementfix, ringperformance, ringtimestampfixes

Children:

4811b1e

Parents:

91c38f8

Message:

• Correctly deal with the differences between PPP over HDLC and CHDLC - we can now decode both link headers correctly (tested against IPLS and Leipzig traces)

Location:

lib

Files:

• format_legacy.c (modified) (1 diff)
• protocols_l2.c (modified) (4 diffs)

lib/format_legacy.c

@@ -349 +349 @@
          *      - Perry Lorier (2008-11-04)
          */
+        
+        /* It can also be CHDLC, which is different again */
+        
+        /* This check matchs PPP over HDLC, a la RFC 1662 */
         if (((char *)packet->payload)[0] == '\xFF'
                 && ((char*)packet->payload)[1] == '\x03')
                 return TRACE_TYPE_POS;
+        
+        /* This check matches unicast CHDLC */
+        else if (((char *)packet->payload)[0] == '\x0F' &&
+                ((char*)packet->payload)[1] == '\x00')
+                return TRACE_TYPE_HDLC_POS;
+        
+        /* This check matches broadcast CHDLC */
+        else if (((char *)packet->payload)[0] == '\x8F' &&
+                ((char*)packet->payload)[1] == '\x00')
+                return TRACE_TYPE_HDLC_POS;
+
+        /* Otherwise just assume raw PPP (?) */
         else 
                 return TRACE_TYPE_PPP;

lib/protocols_l2.c

@@ -251 +251 @@
 }
         
-
+/* Header for CHDLC framing */
 typedef struct libtrace_chdlc_t {
         uint8_t address;        /** 0xF0 for unicast, 0xF8 for multicast */
-        uint8_t control;
+        uint8_t control;        /** Always 0x00 */
         uint16_t ethertype;
 } libtrace_chdlc_t;
 
-static void *trace_get_payload_from_chdlc(void *link, 
+/* Header for PPP in HDLC-like framing */
+typedef struct libtrace_ppp_hdlc_t {
+        uint8_t address;        /** Always should be 0xff */
+        uint8_t control;        /** Always should be 0x03 */
+        uint16_t protocol;      
+} libtrace_ppp_hdlc_t;
+
+static void *trace_get_payload_from_chdlc(void *link, uint16_t *type,
+                uint32_t *remaining) {
+
+        libtrace_chdlc_t *chdlc = (libtrace_chdlc_t *)link;
+
+        if (remaining) {
+                if (*remaining < sizeof(libtrace_chdlc_t)) {
+                        *remaining = 0;
+                        return NULL;
+                }
+                *remaining -= sizeof(libtrace_chdlc_t);
+        }
+
+        if (type) {
+                *type = ntohs(chdlc->ethertype);
+        }
+
+        return (void *)((char *)chdlc + sizeof(*chdlc));
+
+}
+
+static void *trace_get_payload_from_ppp_hdlc(void *link, 
                 uint16_t *type, uint32_t *remaining)
 {
-        libtrace_chdlc_t *chdlc = (libtrace_chdlc_t*)link;
-
-        if (remaining) {
-                if (*remaining < sizeof(libtrace_chdlc_t)) {
-                        *remaining = 0;
-                        return NULL;
-                }
-                *remaining-=sizeof(libtrace_chdlc_t);
+        libtrace_ppp_hdlc_t *ppp_hdlc = (libtrace_ppp_hdlc_t*)link;
+
+        if (remaining) {
+                if (*remaining < sizeof(libtrace_ppp_hdlc_t)) {
+                        *remaining = 0;
+                        return NULL;
+                }
+                *remaining-=sizeof(libtrace_ppp_hdlc_t);
         }
 
         if (type) {
-                switch(ntohs(chdlc->ethertype)) {
+                /* http://www.iana.org/assignments/ppp-numbers */
+
+                switch(ntohs(ppp_hdlc->protocol)) {
                         case 0x0021: /* IP */
                                 *type = TRACE_ETHERTYPE_IP;
@@ -281 +311 @@
 
                         default:
-                                printf("Unknown chdlc type: %04x\n",ntohs(chdlc->ethertype));
+                                printf("Unknown chdlc type: %04x\n",
+                                                ntohs(ppp_hdlc->protocol));
                                 *type = 0; /* Unknown */
                 }
@@ -287 +318 @@
 
 
-        return (void*)((char *)chdlc+sizeof(*chdlc));
+        return (void*)((char *)ppp_hdlc+sizeof(*ppp_hdlc));
 }
 
@@ -413 +444 @@
                                         remaining);
                 case TRACE_TYPE_POS:
-                        return trace_get_payload_from_chdlc(link,ethertype,
+                        return trace_get_payload_from_ppp_hdlc(link,ethertype,
                                         remaining);
                 /* TODO: Unsupported */