updating Mark C Browns information
[obnox/wireshark/wip.git] / wiretap / nettl.c
index cff3ef3b0ff9332ecf9837ecbab75996356e8fa0..1a918636ef5eb1e9598806dec078a4eabc3f1bd7 100644 (file)
@@ -5,6 +5,9 @@
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
  *
+ * Enhancements by Mark C. Brown <mbrown@hp.com>
+ * Copyright (C) 2003, 2005 Hewlett-Packard Development Company, L.P.
+ *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2
@@ -39,6 +42,19 @@ static guchar nettl_magic_hpux10[12] = {
     0x54, 0x52, 0x00, 0x64, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80
 };
 
+/* HP nettl file header */
+struct nettl_file_hdr {
+    guchar     magic[12];
+    guchar     file_name[56];
+    guchar     tz[20];
+    guchar     host_name[9];
+    guchar     os_vers[9];
+    guchar     os_v;
+    guint8     xxa[8];
+    guchar     model[11];
+    guint16    unknown;
+};
+
 /* HP nettl record header for the SX25L2 subsystem - The FCS is not included in the file. */
 struct nettlrec_sx25l2_hdr {
     guint8     xxa[8];
@@ -54,17 +70,28 @@ struct nettlrec_sx25l2_hdr {
 
 /* HP nettl record header for the NS_LS_IP subsystem */
 /* This also works for BASE100 and GSC100BT */
+/* see /usr/include/sys/netdiag1.h for hints */
 struct nettlrec_ns_ls_ip_hdr {
-    guint8     xxa[8];
-    guint8     rectype;
-    guint8     xxb[19];
-    guint8     caplen[4];
-    guint8     length[4];
-    guint8     sec[4];
-    guint8     usec[4];
-    guint8     xxc[16];
+    guint32    devid;
+    guint8     xxa[4];
+    guint32    kind;
+    guint8     xxb[16];
+    guint32    caplen;
+    guint32    length;
+    guint32    sec;
+    guint32    usec;
+    guint32    pid;
+    guint8     xxc[10];
+    guint16    uid;
 };
 
+/* Full record header for writing out a nettl file */
+struct nettlrec_dump_hdr {
+    guint16    hdr_len;
+    guint16    subsys;
+    struct     nettlrec_ns_ls_ip_hdr hdr;
+    guint8     xxd[4];
+};
 
 /* header is followed by data and once again the total length (2 bytes) ! */
 
@@ -136,10 +163,14 @@ static int nettl_read_rec_header(wtap *wth, FILE_T fh,
 static gboolean nettl_read_rec_data(FILE_T fh, guchar *pd, int length,
                int *err, gboolean fddihack);
 static void nettl_close(wtap *wth);
+static gboolean nettl_dump(wtap_dumper *wdh, const struct wtap_pkthdr *phdr,
+    const union wtap_pseudo_header *pseudo_header, const guchar *pd, int *err);
 
 int nettl_open(wtap *wth, int *err, gchar **err_info _U_)
 {
     char magic[12], os_vers[2];
+    guint16 dummy[2];
+    int subsys;
     int bytes_read;
 
     /* Read in the string that should be at the start of a HP file */
@@ -184,6 +215,46 @@ int nettl_open(wtap *wth, int *err, gchar **err_info _U_)
     wth->subtype_close = nettl_close;
     wth->snapshot_length = 0;  /* not available in header, only in frame */
 
+    /* read the first header to take a guess at the file encap */
+    bytes_read = file_read(dummy, 1, 4, wth->fh);
+    if (bytes_read != 4) {
+        if (*err != 0)
+            return -1;
+        if (bytes_read != 0) {
+            *err = WTAP_ERR_SHORT_READ;
+            return -1;
+        }
+        return 0;
+    }
+
+    subsys = g_ntohs(dummy[1]);
+    switch (subsys) {
+        case NETTL_SUBSYS_HPPB_FDDI :
+        case NETTL_SUBSYS_EISA_FDDI :
+        case NETTL_SUBSYS_PCI_FDDI :
+        case NETTL_SUBSYS_HSC_FDDI :
+               wth->file_encap = WTAP_ENCAP_NETTL_FDDI;
+               break;
+        case NETTL_SUBSYS_TOKEN :
+        case NETTL_SUBSYS_PCI_TR :
+               wth->file_encap = WTAP_ENCAP_NETTL_TOKEN_RING;
+               break;
+        case NETTL_SUBSYS_NS_LS_IP :
+        case NETTL_SUBSYS_NS_LS_LOOPBACK :
+        case NETTL_SUBSYS_NS_LS_TCP :
+        case NETTL_SUBSYS_NS_LS_UDP :
+        case NETTL_SUBSYS_NS_LS_IPV6 :
+               wth->file_encap = WTAP_ENCAP_NETTL_RAW_IP;
+               break;
+       default:
+               /* If this assumption is bad, the read will catch it */
+               wth->file_encap = WTAP_ENCAP_NETTL_ETHERNET;
+    }
+
+    if (file_seek(wth->fh, 0x80, SEEK_SET, err) == -1)
+       return -1;
+    wth->data_offset = 0x80;
+
     return 1;
 }
 
@@ -271,9 +342,9 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
     struct nettlrec_ns_ls_drv_eth_hdr drv_eth_hdr;
     guint16 length;
     int offset = 0;
-    int encap;
+    int subsys;
     int padlen;
-    guint8 dummy[4];
+    guint16 dummy[2];
     guchar dummyc[12];
 
     errno = WTAP_ERR_CANT_READ;
@@ -289,21 +360,26 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
        return 0;
     }
     offset += 4;
-    encap=dummy[3];
 
-    switch (encap) {
+    subsys = g_ntohs(dummy[1]);
+    switch (subsys) {
        case NETTL_SUBSYS_LAN100 :
+       case NETTL_SUBSYS_EISA100BT :
        case NETTL_SUBSYS_BASE100 :
        case NETTL_SUBSYS_GSC100BT :
        case NETTL_SUBSYS_PCI100BT :
        case NETTL_SUBSYS_SPP100BT :
+       case NETTL_SUBSYS_100VG :
        case NETTL_SUBSYS_GELAN :
        case NETTL_SUBSYS_BTLAN :
        case NETTL_SUBSYS_INTL100 :
        case NETTL_SUBSYS_IGELAN :
        case NETTL_SUBSYS_IETHER :
+       case NETTL_SUBSYS_IXGBE :
        case NETTL_SUBSYS_HPPB_FDDI :
+       case NETTL_SUBSYS_EISA_FDDI :
         case NETTL_SUBSYS_PCI_FDDI :
+        case NETTL_SUBSYS_HSC_FDDI :
         case NETTL_SUBSYS_TOKEN :
         case NETTL_SUBSYS_PCI_TR :
        case NETTL_SUBSYS_NS_LS_IP :
@@ -315,26 +391,26 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
        case NETTL_SUBSYS_NS_LS_IPV6 :
        case NETTL_SUBSYS_NS_LS_ICMPV6 :
        case NETTL_SUBSYS_NS_LS_ICMP :
-           if( (encap == NETTL_SUBSYS_NS_LS_IP)
-            || (encap == NETTL_SUBSYS_NS_LS_LOOPBACK)
-            || (encap == NETTL_SUBSYS_NS_LS_UDP)
-            || (encap == NETTL_SUBSYS_NS_LS_TCP)
-            || (encap == NETTL_SUBSYS_NS_LS_IPV6)) {
-               phdr->pkt_encap = WTAP_ENCAP_RAW_IP;
-           } else if (encap == NETTL_SUBSYS_NS_LS_ICMP) {
-               phdr->pkt_encap = WTAP_ENCAP_RAW_ICMP;
-           } else if (encap == NETTL_SUBSYS_NS_LS_ICMPV6) {
-               phdr->pkt_encap = WTAP_ENCAP_RAW_ICMPV6;
-           } else if( (encap == NETTL_SUBSYS_HPPB_FDDI)
-                   || (encap == NETTL_SUBSYS_PCI_FDDI) ) {
-               phdr->pkt_encap = WTAP_ENCAP_FDDI;
-           } else if( (encap == NETTL_SUBSYS_PCI_TR)
-                   || (encap == NETTL_SUBSYS_TOKEN) ) {
-               phdr->pkt_encap = WTAP_ENCAP_TOKEN_RING;
+           if( (subsys == NETTL_SUBSYS_NS_LS_IP)
+            || (subsys == NETTL_SUBSYS_NS_LS_LOOPBACK)
+            || (subsys == NETTL_SUBSYS_NS_LS_UDP)
+            || (subsys == NETTL_SUBSYS_NS_LS_TCP)
+            || (subsys == NETTL_SUBSYS_NS_LS_IPV6)) {
+               phdr->pkt_encap = WTAP_ENCAP_NETTL_RAW_IP;
+           } else if (subsys == NETTL_SUBSYS_NS_LS_ICMP) {
+               phdr->pkt_encap = WTAP_ENCAP_NETTL_RAW_ICMP;
+           } else if (subsys == NETTL_SUBSYS_NS_LS_ICMPV6) {
+               phdr->pkt_encap = WTAP_ENCAP_NETTL_RAW_ICMPV6;
+           } else if( (subsys == NETTL_SUBSYS_HPPB_FDDI)
+                   || (subsys == NETTL_SUBSYS_EISA_FDDI)
+                   || (subsys == NETTL_SUBSYS_PCI_FDDI)
+                   || (subsys == NETTL_SUBSYS_HSC_FDDI) ) {
+               phdr->pkt_encap = WTAP_ENCAP_NETTL_FDDI;
+           } else if( (subsys == NETTL_SUBSYS_PCI_TR)
+                   || (subsys == NETTL_SUBSYS_TOKEN) ) {
+               phdr->pkt_encap = WTAP_ENCAP_NETTL_TOKEN_RING;
            } else {
-               phdr->pkt_encap = WTAP_ENCAP_ETHERNET;
-               /* We assume there's no FCS in this frame. */
-               pseudo_header->eth.fcs_len = 0;
+               phdr->pkt_encap = WTAP_ENCAP_NETTL_ETHERNET;
            }
 
            bytes_read = file_read(&ip_hdr, 1, sizeof ip_hdr, fh);
@@ -368,8 +444,8 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
            }
 
            /* HPPB FDDI has different inbound vs outbound trace records */
-           if (encap == NETTL_SUBSYS_HPPB_FDDI) {
-                if (ip_hdr.rectype == NETTL_HDR_PDUIN) {
+           if (subsys == NETTL_SUBSYS_HPPB_FDDI) {
+                if (pntohl(&ip_hdr.kind) == NETTL_HDR_PDUIN) {
                    /* inbound is very strange...
                       there are an extra 3 bytes after the DSAP and SSAP
                       for SNAP frames ???
@@ -379,10 +455,9 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
                   if (length <= 0)
                       return 0;
                   phdr->len = length;
-                  length = pntohl(&ip_hdr.caplen);
-                  phdr->caplen = length;
+                  phdr->caplen = pntohl(&ip_hdr.caplen);
                 } else {
-                  /* outbound has an extra padding */
+                  /* outbound appears to have variable padding */
                   bytes_read = file_read(dummyc, 1, 9, fh);
                   if (bytes_read != 9) {
                       *err = file_error(fh);
@@ -416,8 +491,10 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
                   length = pntohl(&ip_hdr.caplen);
                   phdr->caplen = length - padlen;
                }
-           } else if (encap == NETTL_SUBSYS_PCI_FDDI) {
-               /* PCI FDDI has an extra 3 bytes of padding */
+           } else if ( (subsys == NETTL_SUBSYS_PCI_FDDI)
+                    || (subsys == NETTL_SUBSYS_EISA_FDDI)
+                    || (subsys == NETTL_SUBSYS_HSC_FDDI) ) {
+               /* other flavor FDDI cards have an extra 3 bytes of padding */
                bytes_read = file_read(dummy, 1, 3, fh);
                if (bytes_read != 3) {
                    *err = file_error(fh);
@@ -436,7 +513,7 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
                phdr->len = length - 3;
                length = pntohl(&ip_hdr.caplen);
                phdr->caplen = length - 3;
-           } else if (encap == NETTL_SUBSYS_NS_LS_LOOPBACK) {
+           } else if (subsys == NETTL_SUBSYS_NS_LS_LOOPBACK) {
                /* LOOPBACK has an extra 26 bytes of padding */
                bytes_read = file_read(dummy, 1, 26, fh);
                if (bytes_read != 26) {
@@ -461,8 +538,7 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
                if (length <= 0)
                    return 0;
                phdr->len = length;
-               length = pntohl(&ip_hdr.caplen);
-               phdr->caplen = length;
+               phdr->caplen = pntohl(&ip_hdr.caplen);
            }
 
            phdr->ts.tv_sec = pntohl(&ip_hdr.sec);
@@ -502,9 +578,7 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
            /* XXX we dont know how to identify this as ethernet frames, so
               we assumes everything is. We will crash and burn for anything else */
            /* for encapsulated 100baseT we do this */
-           phdr->pkt_encap = WTAP_ENCAP_ETHERNET;
-           /* We assume there's no FCS in this frame. */
-           pseudo_header->eth.fcs_len = 0;
+           phdr->pkt_encap = WTAP_ENCAP_NETTL_ETHERNET;
            bytes_read = file_read(&drv_eth_hdr, 1, sizeof drv_eth_hdr, fh);
            if (bytes_read != sizeof drv_eth_hdr) {
                *err = file_error(fh);
@@ -521,8 +595,7 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
            length = pntohs(&drv_eth_hdr.length); 
            if (length <= 0) return 0;
            phdr->len = length;
-           length = pntohs(&drv_eth_hdr.caplen);
-           phdr->caplen = length;
+           phdr->caplen = pntohs(&drv_eth_hdr.caplen);
 
            phdr->ts.tv_sec = pntohl(&ip_hdr.sec);
            phdr->ts.tv_usec = pntohl(&ip_hdr.usec);
@@ -568,11 +641,48 @@ nettl_read_rec_header(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
                (lapb_hdr.from_dce & 0x20 ? FROM_DCE : 0x00);
            break;
        default:
-           *err = WTAP_ERR_UNSUPPORTED_ENCAP;
-           *err_info = g_strdup_printf("nettl: subsystem %u unknown or unsupported",
-                   encap);
-           return -1;
+           wth->file_encap = WTAP_ENCAP_PER_PACKET;
+           phdr->pkt_encap = WTAP_ENCAP_NETTL_UNKNOWN;
+            bytes_read = file_read(&ip_hdr, 1, sizeof ip_hdr, fh);
+            if (bytes_read != sizeof ip_hdr) {
+                *err = file_error(fh);
+                if (*err != 0)
+                    return -1;
+                if (bytes_read != 0) {
+                    *err = WTAP_ERR_SHORT_READ;
+                    return -1;
+                }
+                return 0;
+            }
+            offset += sizeof ip_hdr;
+            length = pntohl(&ip_hdr.length);
+            if (length <= 0) return 0;
+            phdr->len = length;
+            phdr->caplen = pntohl(&ip_hdr.caplen);
+            phdr->ts.tv_sec = pntohl(&ip_hdr.sec);
+            phdr->ts.tv_usec = pntohl(&ip_hdr.usec);
+            if (wth->capture.nettl->is_hpux_11) {
+                bytes_read = file_read(dummy, 1, 4, fh);
+                if (bytes_read != 4) {
+                    *err = file_error(fh);
+                    if (*err != 0)
+                        return -1;
+                    if (bytes_read != 0) {
+                        *err = WTAP_ERR_SHORT_READ;
+                        return -1;
+                    }
+                    return 0;
+                }
+                offset += 4;
+            }
     }
+
+    pseudo_header->nettl.subsys   = subsys;
+    pseudo_header->nettl.devid    = pntohl(&ip_hdr.devid);
+    pseudo_header->nettl.kind     = pntohl(&ip_hdr.kind);
+    pseudo_header->nettl.pid      = pntohl(&ip_hdr.pid);
+    pseudo_header->nettl.uid      = pntohs(&ip_hdr.uid);
+
     return offset;
 }
 
@@ -584,22 +694,22 @@ nettl_read_rec_data(FILE_T fh, guchar *pd, int length, int *err, gboolean fddiha
     guint8 dummy[3];
 
     if (fddihack == TRUE) {
-       /* read in FC, dest, src and DSAP */
-       if (file_read(pd, 1, 14, fh) == 14) {
+       /* read in FC, dest, src, DSAP and SSAP */
+       if (file_read(pd, 1, 15, fh) == 15) {
           if (pd[13] == 0xAA) {
              /* it's SNAP, have to eat 3 bytes??? */
              if (file_read(dummy, 1, 3, fh) == 3) {
-                p=pd+14;
-                bytes_read = file_read(p, 1, length-17, fh);
-                bytes_read += 17;
+                p=pd+15;
+                bytes_read = file_read(p, 1, length-18, fh);
+                bytes_read += 18;
              } else {
                 bytes_read = -1;
              }
           } else {
              /* not SNAP */
-             p=pd+14;
-             bytes_read = file_read(p, 1, length-14, fh);
-             bytes_read += 14;
+             p=pd+15;
+             bytes_read = file_read(p, 1, length-15, fh);
+             bytes_read += 15;
           }
        } else
           bytes_read = -1;
@@ -619,3 +729,172 @@ static void nettl_close(wtap *wth)
 {
     g_free(wth->capture.nettl);
 }
+
+
+/* Returns 0 if we could write the specified encapsulation type,
+   an error indication otherwise.  nettl files are WTAP_ENCAP_UNKNOWN
+   when they are first opened, so we allow that for tethereal read/write.
+ */
+
+int nettl_dump_can_write_encap(int encap)
+{
+
+       switch (encap) {
+               case WTAP_ENCAP_ETHERNET:
+               case WTAP_ENCAP_FDDI_BITSWAPPED:
+               case WTAP_ENCAP_TOKEN_RING:
+               case WTAP_ENCAP_NETTL_ETHERNET:
+               case WTAP_ENCAP_NETTL_FDDI:
+               case WTAP_ENCAP_NETTL_TOKEN_RING:
+               case WTAP_ENCAP_NETTL_RAW_IP:
+               case WTAP_ENCAP_NETTL_RAW_ICMP:
+               case WTAP_ENCAP_NETTL_RAW_ICMPV6:
+               case WTAP_ENCAP_PER_PACKET:
+               case WTAP_ENCAP_UNKNOWN:
+               case WTAP_ENCAP_NETTL_UNKNOWN:
+                       return 0;
+               default:
+                       return WTAP_ERR_UNSUPPORTED_ENCAP;
+       }
+}
+
+
+/* Returns TRUE on success, FALSE on failure;
+   sets "*err" to an error code on failure */
+gboolean nettl_dump_open(wtap_dumper *wdh, gboolean cant_seek _U_, int *err)
+{
+       struct nettl_file_hdr file_hdr;
+       size_t nwritten;
+
+       /* This is a nettl file */
+       wdh->subtype_write = nettl_dump;
+       wdh->subtype_close = NULL;
+
+       /* Write the file header. */
+       memset(&file_hdr,0,sizeof(file_hdr));
+       memcpy(file_hdr.magic,nettl_magic_hpux10,sizeof(file_hdr.magic));
+       strcpy(file_hdr.file_name,"/tmp/ethereal.TRC000");
+       strcpy(file_hdr.tz,"UTC");
+       strcpy(file_hdr.host_name,"ethereal");
+       strcpy(file_hdr.os_vers,"B.11.11");
+       file_hdr.os_v=0x55;
+       strcpy(file_hdr.model,"9000/800");
+       file_hdr.unknown=g_htons(0x406);
+       nwritten = fwrite(&file_hdr, 1, sizeof file_hdr, wdh->fh);
+       if (nwritten != sizeof(file_hdr)) {
+               if (nwritten == 0 && ferror(wdh->fh))
+                       *err = errno;
+               else
+                       *err = WTAP_ERR_SHORT_WRITE;
+               return FALSE;
+       }
+       wdh->bytes_dumped += sizeof(file_hdr);
+
+       return TRUE;
+}
+
+/* Write a record for a packet to a dump file.
+   Returns TRUE on success, FALSE on failure. */
+static gboolean nettl_dump(wtap_dumper *wdh,
+       const struct wtap_pkthdr *phdr,
+       const union wtap_pseudo_header *pseudo_header _U_,
+       const guchar *pd, int *err)
+{
+       struct nettlrec_dump_hdr rec_hdr;
+       guint32 dummy=0;
+       size_t nwritten;
+
+       memset(&rec_hdr,0,sizeof(rec_hdr));
+       rec_hdr.hdr_len = g_htons(sizeof(rec_hdr));
+       rec_hdr.hdr.kind = g_htonl(NETTL_HDR_PDUIN);
+       rec_hdr.hdr.sec = g_htonl(phdr->ts.tv_sec);
+       rec_hdr.hdr.usec = g_htonl(phdr->ts.tv_usec);
+       rec_hdr.hdr.caplen = g_htonl(phdr->caplen);
+       rec_hdr.hdr.length = g_htonl(phdr->len);
+       rec_hdr.hdr.devid = -1;
+       rec_hdr.hdr.pid = -1;
+       rec_hdr.hdr.uid = -1;
+
+       switch (phdr->pkt_encap) {
+
+               case WTAP_ENCAP_NETTL_FDDI:
+                       /* account for pad bytes */
+                       rec_hdr.hdr.caplen = g_htonl(phdr->caplen + 3);
+                       rec_hdr.hdr.length = g_htonl(phdr->len + 3);
+                        /* fall through and fill the rest of the fields */
+               case WTAP_ENCAP_NETTL_ETHERNET:
+               case WTAP_ENCAP_NETTL_TOKEN_RING:
+               case WTAP_ENCAP_NETTL_RAW_IP:
+               case WTAP_ENCAP_NETTL_RAW_ICMP:
+               case WTAP_ENCAP_NETTL_RAW_ICMPV6:
+               case WTAP_ENCAP_NETTL_UNKNOWN:
+                       rec_hdr.subsys = g_htons(pseudo_header->nettl.subsys);
+                       rec_hdr.hdr.devid = g_htonl(pseudo_header->nettl.devid);
+                       rec_hdr.hdr.kind = g_htonl(pseudo_header->nettl.kind);
+                       rec_hdr.hdr.pid = g_htonl(pseudo_header->nettl.pid);
+                       rec_hdr.hdr.uid = g_htons(pseudo_header->nettl.uid);
+                       break;
+
+               case WTAP_ENCAP_RAW_IP:
+                       rec_hdr.subsys = g_htons(NETTL_SUBSYS_NS_LS_IP);
+                       break;
+
+               case WTAP_ENCAP_ETHERNET:
+                       rec_hdr.subsys = g_htons(NETTL_SUBSYS_BTLAN);
+                       break;
+
+               case WTAP_ENCAP_FDDI_BITSWAPPED:
+                       rec_hdr.subsys = g_htons(NETTL_SUBSYS_PCI_FDDI);
+                       /* account for pad bytes */
+                       rec_hdr.hdr.caplen = g_htonl(phdr->caplen + 3);
+                       rec_hdr.hdr.length = g_htonl(phdr->len + 3);
+                       break;
+
+               case WTAP_ENCAP_TOKEN_RING:
+                       rec_hdr.subsys = g_htons(NETTL_SUBSYS_PCI_TR);
+                       break;
+       
+               default:
+                       /* found one we don't support */
+                       *err = WTAP_ERR_UNSUPPORTED_ENCAP;
+                       return FALSE;
+       }
+
+       nwritten = fwrite(&rec_hdr, 1, sizeof(rec_hdr), wdh->fh);
+       if (nwritten != sizeof(rec_hdr)) {
+               if (nwritten == 0 && ferror(wdh->fh))
+                       *err = errno;
+               else
+                       *err = WTAP_ERR_SHORT_WRITE;
+               return FALSE;
+       }
+       wdh->bytes_dumped += sizeof(rec_hdr);
+
+       if ((phdr->pkt_encap == WTAP_ENCAP_FDDI_BITSWAPPED) ||
+           (phdr->pkt_encap == WTAP_ENCAP_NETTL_FDDI)) {
+               /* add those weird 3 bytes of padding */
+               nwritten = fwrite(&dummy, 1, 3, wdh->fh);
+               if (nwritten != 3) {
+                       if (nwritten == 0 && ferror(wdh->fh))
+                               *err = errno;
+                       else
+                               *err = WTAP_ERR_SHORT_WRITE;
+                       return FALSE;
+               }
+               wdh->bytes_dumped += 3;
+       }
+
+       /* write actual PDU data */
+
+       nwritten = fwrite(pd, 1, phdr->caplen, wdh->fh);
+       if (nwritten != phdr->caplen) {
+               if (nwritten == 0 && ferror(wdh->fh))
+                       *err = errno;
+               else
+                       *err = WTAP_ERR_SHORT_WRITE;
+               return FALSE;
+       }
+        wdh->bytes_dumped += phdr->caplen;
+
+       return TRUE;
+}