libsmb: Factor out reparse_buffer_marshall from symlink_reparse_buffer_marshall()

Make it easier to play with reparse points

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

2 files changed, 80 insertions, 22 deletions

diff --git a/libcli/smb/reparse_symlink.c b/libcli/smb/reparse_symlink.c
index 31a438013fc..51570b563e4 100644
--- a/libcli/smb/reparse_symlink.c
+++ b/libcli/smb/reparse_symlink.c
@@ -28,6 +28,39 @@
 #include "libcli/smb/smb_util.h"
 #include "lib/util/debug.h"
 
+ssize_t reparse_buffer_marshall(
+	uint32_t reparse_tag,
+	uint16_t reserved,
+	const struct iovec *iov,
+	int iovlen,
+	uint8_t *buf,
+	size_t buflen)
+{
+	ssize_t reparse_data_length = iov_buflen(iov, iovlen);
+	size_t needed;
+
+	if (reparse_data_length == -1) {
+		return -1;
+	}
+	if (reparse_data_length > UINT16_MAX) {
+		return -1;
+	}
+
+	needed = reparse_data_length + 8;
+	if (needed < reparse_data_length) {
+		return -1;
+	}
+
+	if (buflen >= needed) {
+		PUSH_LE_U32(buf, 0, reparse_tag);
+		PUSH_LE_U16(buf, 4, reparse_data_length);
+		PUSH_LE_U16(buf, 6, reserved);
+		iov_buf(iov, iovlen, buf+8, buflen-8);
+	}
+
+	return needed;
+}
+
 bool symlink_reparse_buffer_marshall(
 	const char *substitute,
 	const char *printname,
@@ -37,8 +70,10 @@ bool symlink_reparse_buffer_marshall(
 	uint8_t **pdst,
 	size_t *pdstlen)
 {
+	uint8_t sbuf[12];
+	struct iovec iov[3];
 	uint8_t *dst = NULL;
-	size_t dst_len;
+	ssize_t dst_len;
 	uint8_t *subst_utf16 = NULL;
 	uint8_t *print_utf16 = NULL;
 	size_t subst_len = 0;
@@ -53,6 +88,8 @@ bool symlink_reparse_buffer_marshall(
 		printname = substitute;
 	}
 
+	iov[0] = (struct iovec) { .iov_base = sbuf, .iov_len = sizeof(sbuf), };
+
 	ok = convert_string_talloc(
 		mem_ctx,
 		CH_UNIX,
@@ -64,6 +101,12 @@ bool symlink_reparse_buffer_marshall(
 	if (!ok) {
 		goto fail;
 	}
+	if (subst_len > UINT16_MAX) {
+		goto fail;
+	}
+	iov[1] = (struct iovec) {
+		.iov_base = subst_utf16, .iov_len = subst_len,
+	};
 
 	ok = convert_string_talloc(
 		mem_ctx,
@@ -76,36 +119,42 @@ bool symlink_reparse_buffer_marshall(
 	if (!ok) {
 		goto fail;
 	}
-
-	dst_len = subst_len + 20;
-	if (dst_len < 20) {
+	if (print_len > UINT16_MAX) {
 		goto fail;
 	}
-	dst_len += print_len;
-	if (dst_len < print_len) {
+	iov[2] = (struct iovec) {
+		.iov_base = print_utf16, .iov_len = print_len,
+	};
+
+	PUSH_LE_U16(sbuf, 0, 0);	 /* SubstituteNameOffset */
+	PUSH_LE_U16(sbuf, 2, subst_len); /* SubstituteNameLength */
+	PUSH_LE_U16(sbuf, 4, subst_len); /* PrintNameOffset */
+	PUSH_LE_U16(sbuf, 6, print_len); /* PrintNameLength */
+	PUSH_LE_U32(sbuf, 8, flags);	 /* Flags */
+
+	dst_len = reparse_buffer_marshall(
+		IO_REPARSE_TAG_SYMLINK,
+		unparsed_path_length,
+		iov,
+		ARRAY_SIZE(iov),
+		NULL,
+		0);
+	if (dst_len == -1) {
 		goto fail;
 	}
+
 	dst = talloc_array(mem_ctx, uint8_t, dst_len);
 	if (dst == NULL) {
 		goto fail;
 	}
 
-	SIVAL(dst, 0, IO_REPARSE_TAG_SYMLINK);	   /* ReparseTag */
-	SSVAL(dst, 4, 12 + subst_len + print_len); /* ReparseDataLength */
-	SSVAL(dst, 6, unparsed_path_length);	   /* Reserved */
-	SSVAL(dst, 8, 0);			   /* SubstituteNameOffset */
-	SSVAL(dst, 10, subst_len);		   /* SubstituteNameLength */
-	SSVAL(dst, 12, subst_len);		   /* PrintNameOffset */
-	SSVAL(dst, 14, print_len);		   /* PrintNameLength */
-	SIVAL(dst, 16, flags);			   /* Flags */
-
-	if ((subst_utf16 != NULL) && (subst_len != 0)) {
-		memcpy(dst + 20, subst_utf16, subst_len);
-	}
-
-	if ((print_utf16 != NULL) && (print_len != 0)) {
-		memcpy(dst + 20 + subst_len, print_utf16, print_len);
-	}
+	reparse_buffer_marshall(
+		IO_REPARSE_TAG_SYMLINK,
+		unparsed_path_length,
+		iov,
+		ARRAY_SIZE(iov),
+		dst,
+		dst_len);
 
 	*pdst = dst;
 	*pdstlen = dst_len;
diff --git a/libcli/smb/reparse_symlink.h b/libcli/smb/reparse_symlink.h
index 7791d71663e..2f57a592eec 100644
--- a/libcli/smb/reparse_symlink.h
+++ b/libcli/smb/reparse_symlink.h
@@ -25,6 +25,7 @@
 
 #include "replace.h"
 #include <talloc.h>
+#include "lib/util/iov_buf.h"
 
 struct symlink_reparse_struct {
 	uint16_t unparsed_path_length; /* reserved for the reparse point */
@@ -33,6 +34,14 @@ struct symlink_reparse_struct {
 	uint32_t flags;
 };
 
+ssize_t reparse_buffer_marshall(
+	uint32_t reparse_tag,
+	uint16_t reserved,
+	const struct iovec *iov,
+	int iovlen,
+	uint8_t *buf,
+	size_t buflen);
+
 bool symlink_reparse_buffer_marshall(
 	const char *substitute,
 	const char *printname,