Remove the "union pseudo_header" from the "frame_data" structure;

there's no need to keep it around in memory - when the frame data is
read in when handing a frame, read in the information, if any, necessary
to reconstruct the frame header, and reconstruct it.  This saves some
memory.

This requires that the seek-and-read function be implemented inside
Wiretap, and that the Wiretap handle remain open even after we've
finished reading the file sequentially.

This also points out that we can't really do X.25-over-Ethernet
correctly, as we don't know where the direction (DTE->DCE or DCE->DTE)
flag is stored; it's not clear how the Ethernet type 0x0805 for X.25
Layer 3 is supposed to be handled in any case.  We eliminate
X.25-over-Ethernet support (until we find out what we're supposed to
do).

svn path=/trunk/; revision=1975

1 files changed, 114 insertions, 39 deletions

diff --git a/wiretap/i4btrace.c b/wiretap/i4btrace.c
index c03f7be871..04b52c4ff1 100644
--- a/wiretap/i4btrace.c
+++ b/wiretap/i4btrace.c
@@ -1,6 +1,6 @@
 /* i4btrace.c
  *
- * $Id: i4btrace.c,v 1.4 2000/04/15 21:12:37 guy Exp $
+ * $Id: i4btrace.c,v 1.5 2000/05/18 09:09:27 guy Exp $
  *
  * Wiretap Library
  * Copyright (c) 1999 by Bert Driehuis <driehuis@playbeing.org>
@@ -33,6 +33,11 @@
 #include "i4b_trace.h"
 
 static int i4btrace_read(wtap *wth, int *err);
+static int i4btrace_seek_read(wtap *wth, int seek_off,
+    union pseudo_header *pseudo_header, u_char *pd, int length);
+static int i4b_read_rec_header(FILE_T *fh, i4b_trace_hdr_t *hdr, int *err);
+static void i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr);
+static int i4b_read_rec_data(FILE_T *fh, char *pd, int length, int *err);
 
 /*
  * Test some fields in the header to see if they make sense.
@@ -91,6 +96,7 @@ int i4btrace_open(wtap *wth, int *err)
 	wth->file_type = WTAP_FILE_I4BTRACE;
 	wth->capture.i4btrace = g_malloc(sizeof(i4btrace_t));
 	wth->subtype_read = i4btrace_read;
+	wth->subtype_seek_read = i4btrace_seek_read;
 	wth->snapshot_length = 2048;	/* actual length set per packet */
 
 	wth->capture.i4btrace->bchannel_prot[0] = -1;
@@ -107,39 +113,21 @@ int i4btrace_open(wtap *wth, int *err)
 /* Read the next packet */
 static int i4btrace_read(wtap *wth, int *err)
 {
-	int	bytes_read;
+	int	record_offset;
+	int	ret;
 	i4b_trace_hdr_t hdr;
 	guint16 length;
-	int	data_offset;
 	void *bufp;
 
 	/* Read record header. */
-	errno = WTAP_ERR_CANT_READ;
-	bytes_read = file_read(&hdr, 1, sizeof hdr, wth->fh);
-	if (bytes_read != sizeof hdr) {
-		*err = file_error(wth->fh);
-		if (*err != 0)
-			return -1;
-		if (bytes_read != 0) {
-			*err = WTAP_ERR_SHORT_READ;
-			return -1;
-		}
-		return 0;
+	record_offset = wth->data_offset;
+	ret = i4b_read_rec_header(wth->fh, &hdr, err);
+	if (ret <= 0) {
+		/* Read error or EOF */
+		return ret;
 	}
 	wth->data_offset += sizeof hdr;
-	if (wth->capture.i4btrace->byte_swapped) {
-		/*
-		 * Byte-swap the header.
-		 */
-		hdr.length = BSWAP32(hdr.length);
-		hdr.unit = BSWAP32(hdr.unit);
-		hdr.type = BSWAP32(hdr.type);
-		hdr.dir = BSWAP32(hdr.dir);
-		hdr.trunc = BSWAP32(hdr.trunc);
-		hdr.count = BSWAP32(hdr.count);
-		hdr.time.tv_sec = BSWAP32(hdr.time.tv_sec);
-		hdr.time.tv_usec = BSWAP32(hdr.time.tv_usec);
-	}
+	i4b_byte_swap_header(wth, &hdr);
 	length = hdr.length - sizeof(hdr);
 	if (length == 0)
 		return 0;
@@ -150,23 +138,15 @@ static int i4btrace_read(wtap *wth, int *err)
 	wth->phdr.ts.tv_sec = hdr.time.tv_sec;
 	wth->phdr.ts.tv_usec = hdr.time.tv_usec;
 
-	wth->phdr.pseudo_header.x25.flags = (hdr.dir == FROM_TE) ? 0x00 : 0x80;
+	wth->pseudo_header.x25.flags = (hdr.dir == FROM_TE) ? 0x00 : 0x80;
 
 	/*
 	 * Read the packet data.
 	 */
 	buffer_assure_space(wth->frame_buffer, length);
-	data_offset = wth->data_offset;
-	errno = WTAP_ERR_CANT_READ;
 	bufp = buffer_start_ptr(wth->frame_buffer);
-	bytes_read = file_read(bufp, 1, length, wth->fh);
-
-	if (bytes_read != length) {
-		*err = file_error(wth->fh);
-		if (*err == 0)
-			*err = WTAP_ERR_SHORT_READ;
-		return -1;
-	}
+	if (i4b_read_rec_data(wth->fh, bufp, length, err) < 0)
+		return -1;	/* Read error */
 	wth->data_offset += length;
 
 	/*
@@ -200,5 +180,100 @@ static int i4btrace_read(wtap *wth, int *err)
 			wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 	}
 
-	return data_offset;
+	/*
+	 * XXX - there is no file header for i4btrace files, so the
+	 * first record begins at the beginning of the file, hence
+	 * its offset is 0.
+	 *
+	 * Unfortunately, a return value of 0 means "end of file".
+	 *
+	 * Therefore, we return the record offset + 1, and compensate
+	 * for that in "i4btrace_seek_read()".
+	 */
+	return record_offset + 1;
+}
+
+static int
+i4btrace_seek_read(wtap *wth, int seek_off,
+    union pseudo_header *pseudo_header, u_char *pd, int length)
+{
+	int	ret;
+	int	err;		/* XXX - return this */
+	i4b_trace_hdr_t hdr;
+
+	/*
+	 * We subtract 1 because we added 1 before returning the record
+	 * offset in "i4btrace_read()"; see the comment above.
+	 */
+	file_seek(wth->random_fh, seek_off - 1, SEEK_SET);
+
+	/* Read record header. */
+	ret = i4b_read_rec_header(wth->random_fh, &hdr, &err);
+	if (ret <= 0) {
+		/* Read error or EOF */
+		return ret;
+	}
+	i4b_byte_swap_header(wth, &hdr);
+
+	pseudo_header->x25.flags = (hdr.dir == FROM_TE) ? 0x00 : 0x80;
+
+	/*
+	 * Read the packet data.
+	 */
+	return i4b_read_rec_data(wth->random_fh, pd, length, &err);
+}
+
+static int
+i4b_read_rec_header(FILE_T *fh, i4b_trace_hdr_t *hdr, int *err)
+{
+	int	bytes_read;
+
+	errno = WTAP_ERR_CANT_READ;
+	bytes_read = file_read(hdr, 1, sizeof *hdr, fh);
+	if (bytes_read != sizeof *hdr) {
+		*err = file_error(fh);
+		if (*err != 0)
+			return -1;
+		if (bytes_read != 0) {
+			*err = WTAP_ERR_SHORT_READ;
+			return -1;
+		}
+		return 0;
+	}
+	return 1;
+}
+
+static void
+i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr)
+{
+	if (wth->capture.i4btrace->byte_swapped) {
+		/*
+		 * Byte-swap the header.
+		 */
+		hdr->length = BSWAP32(hdr->length);
+		hdr->unit = BSWAP32(hdr->unit);
+		hdr->type = BSWAP32(hdr->type);
+		hdr->dir = BSWAP32(hdr->dir);
+		hdr->trunc = BSWAP32(hdr->trunc);
+		hdr->count = BSWAP32(hdr->count);
+		hdr->time.tv_sec = BSWAP32(hdr->time.tv_sec);
+		hdr->time.tv_usec = BSWAP32(hdr->time.tv_usec);
+	}
+}
+
+static int
+i4b_read_rec_data(FILE_T *fh, char *pd, int length, int *err)
+{
+	int	bytes_read;
+
+	errno = WTAP_ERR_CANT_READ;
+	bytes_read = file_read(pd, 1, length, fh);
+
+	if (bytes_read != length) {
+		*err = file_error(fh);
+		if (*err == 0)
+			*err = WTAP_ERR_SHORT_READ;
+		return -1;
+	}
+	return 0;
 }