Byte-swap the extra fields in the "version 1" USB monitor header.

5 files changed, 72 insertions, 10 deletions

diff --git a/pcap-common.c b/pcap-common.c
index 61509e4..18c45cd 100644
--- a/pcap-common.c
+++ b/pcap-common.c
@@ -1123,9 +1123,10 @@ linktype_to_dlt(int linktype)
  * the reading host's byte order.
  */
 void
-swap_linux_usb_header(const struct pcap_pkthdr *hdr, u_char *buf)
+swap_linux_usb_header(const struct pcap_pkthdr *hdr, u_char *buf,
+    int header_len_64_bytes)
 {
-	pcap_usb_header *uhdr = (pcap_usb_header *)buf;
+	pcap_usb_header_mmapped *uhdr = (pcap_usb_header_mmapped *)buf;
 
 	/*
 	 * The URB id is a totally opaque value; do we really need to 
@@ -1152,4 +1153,27 @@ swap_linux_usb_header(const struct pcap_pkthdr *hdr, u_char *buf)
 	if (hdr->caplen < 40)
 		return;
 	uhdr->data_len = SWAPLONG(uhdr->data_len);
+
+	if (header_len_64_bytes) {
+		/*
+		 * This is either the "version 1" header, with
+		 * 16 bytes of additional fields at the end, or
+		 * a "version 0" header from a memory-mapped
+		 * capture, with 16 bytes of zeroed-out padding
+		 * at the end.  Byte swap them as if this were
+		 * a "version 1" header.
+		 */
+		if (hdr->caplen < 52)
+			return;
+		uhdr->interval = SWAPLONG(uhdr->interval);
+		if (hdr->caplen < 56)
+			return;
+		uhdr->start_frame = SWAPLONG(uhdr->start_frame);
+		if (hdr->caplen < 60)
+			return;
+		uhdr->xfer_flags = SWAPLONG(uhdr->xfer_flags);
+		if (hdr->caplen < 64)
+			return;
+		uhdr->ndesc = SWAPLONG(uhdr->ndesc);
+	}	
 }
diff --git a/pcap-common.h b/pcap-common.h
index f198e86..0c80ba3 100644
--- a/pcap-common.h
+++ b/pcap-common.h
@@ -21,4 +21,5 @@ extern int dlt_to_linktype(int dlt);
 
 extern int linktype_to_dlt(int linktype);
 
-extern void swap_linux_usb_header(const struct pcap_pkthdr *hdr, u_char *buf);
+extern void swap_linux_usb_header(const struct pcap_pkthdr *hdr, u_char *buf,
+    int header_len_64_bytes);
diff --git a/pcap/usb.h b/pcap/usb.h
index d7de2bd..aa35122 100644
--- a/pcap/usb.h
+++ b/pcap/usb.h
@@ -54,7 +54,7 @@
 
 /*
  * USB setup header as defined in USB specification.
- * Appears at the front of each packet in DLT_USB captures.
+ * Appears at the front of each Control S-type packet in DLT_USB captures.
  */
 typedef struct _usb_setup {
 	u_int8_t bmRequestType;
@@ -64,6 +64,13 @@ typedef struct _usb_setup {
 	u_int16_t wLength;
 } pcap_usb_setup;
 
+/*
+ * Information from the URB for Isochronous transfers.
+ */
+typedef struct _iso_rec {
+	int32_t	error_count;
+	int32_t	numdesc;
+} iso_rec;
 
 /*
  * Header prepended by linux kernel to each event.
@@ -87,8 +94,11 @@ typedef struct _usb_header {
 } pcap_usb_header;
 
 /*
- * Header prepended by linux kernel to each event, plus padding in the
- * internal buffer.
+ * Header prepended by linux kernel to each event for the 2.6.31
+ * and later kernels; for the 2.6.21 through 2.6.30 kernels, the
+ * "iso_rec" information, and the fields starting with "interval"
+ * are zeroed-out padding fields.
+ *
  * Appears at the front of each packet in DLT_USB_LINUX_MMAPPED captures.
  */
 typedef struct _usb_header_mmapped {
@@ -105,8 +115,29 @@ typedef struct _usb_header_mmapped {
 	int32_t status;
 	u_int32_t urb_len;
 	u_int32_t data_len; /* amount of urb data really present in this event*/
-	pcap_usb_setup setup;
-	u_int8_t padding[16];
+	union {
+		pcap_usb_setup setup;
+		iso_rec iso;
+	} s;
+	int32_t	interval;	/* for Interrupt and Isochronous events */
+	int32_t start_frame;	/* for Isochronous events */
+	u_int32_t xfer_flags;	/* copy of URB's transfer flags */
+	u_int32_t ndesc;	/* number of isochronous descriptors */
 } pcap_usb_header_mmapped;
 
+/*
+ * Isochronous descriptors; for isochronous transfers there might be
+ * one or more of these at the beginning of the packet data.  The
+ * number of descriptors is given by the "ndesc" field in the header;
+ * as indicated, in older kernels that don't put the descriptors at
+ * the beginning of the packet, that field is zeroed out, so that field
+ * can be trusted even in captures from older kernels.
+ */
+typedef struct _usb_isodesc {
+	int32_t		status;
+	u_int32_t	offset;
+	u_int32_t	len;
+	u_int8_t	pad[4];
+} usb_isodesc;
+
 #endif
diff --git a/sf-pcap-ng.c b/sf-pcap-ng.c
index 54a7363..3535777 100644
--- a/sf-pcap-ng.c
+++ b/sf-pcap-ng.c
@@ -1100,8 +1100,11 @@ found:
 		switch (p->linktype) {
 
 		case DLT_USB_LINUX:
+			swap_linux_usb_header(hdr, *data, 0);
+			break;
+
 		case DLT_USB_LINUX_MMAPPED:
-			swap_linux_usb_header(hdr, *data);
+			swap_linux_usb_header(hdr, *data, 1);
 			break;
 		}
 	}
diff --git a/sf-pcap.c b/sf-pcap.c
index bf0a0ea..6903160 100644
--- a/sf-pcap.c
+++ b/sf-pcap.c
@@ -422,8 +422,11 @@ pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
 		switch (p->linktype) {
 
 		case DLT_USB_LINUX:
+			swap_linux_usb_header(hdr, *data, 0);
+			break;
+
 		case DLT_USB_LINUX_MMAPPED:
-			swap_linux_usb_header(hdr, *data);
+			swap_linux_usb_header(hdr, *data, 1);
 			break;
 		}
 	}