From fc1ae6582fa5e199cc9c50dc2297297c1893955c Mon Sep 17 00:00:00 2001
From: "J.W. Schultz" <jw@samba.org>
Date: Thu, 10 Apr 2003 01:50:12 +0000
Subject: [PATCH]  - for protocol version >= 27, mdfour_tail() is called when
 the block size    (including checksum_seed) is a multiple of 64.  Previously
 it was not    called, giving the wrong MD4 checksum.

 - for protocol version >= 27, a 64 bit bit counter is used in mdfour.c as
   required by the RFC.  Previously only a 32 bit bit counter was used,
   causing incorrect MD4 file checksums for file sizes >= 512MB - 4.
						-- Craig Barratt
---
 checksum.c   | 16 +++++++++++++++-
 lib/mdfour.c | 51 +++++++++++++++++++++++++++++++++++++++------------
 lib/mdfour.h |  5 +++--
 3 files changed, 57 insertions(+), 15 deletions(-)

diff --git a/checksum.c b/checksum.c
index 8e584fab..f9f46d72 100644
--- a/checksum.c
+++ b/checksum.c
@@ -74,7 +74,13 @@ void get_checksum2(char *buf,int len,char *sum)
 	for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
 		mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
 	}
-	if (len - i > 0) {
+	/*
+	 * Prior to version 27 an incorrect MD4 checksum was computed
+	 * by failing to call mdfour_tail() for block sizes that
+	 * are multiples of 64.  This is fixed by calling mdfour_update()
+	 * even when there are no more bytes.
+	 */
+	if (len - i > 0 || remote_version >= 27) {
 		mdfour_update(&m, (uchar *)(buf1+i), (len-i));
 	}
 	
@@ -105,8 +111,16 @@ void file_checksum(char *fname,char *sum,OFF_T size)
 		mdfour_update(&m, (uchar *)tmpchunk, CSUM_CHUNK);
 	}
 
+	/*
+	 * Prior to version 27 an incorrect MD4 checksum was computed
+	 * by failing to call mdfour_tail() for block sizes that
+	 * are multiples of 64.  This is fixed by calling mdfour_update()
+	 * even when there are no more bytes.
+	 */
 	if (len - i > 0) {
 		memcpy(tmpchunk, map_ptr(buf,i,len-i), len-i);
+	}
+	if (len - i > 0 || remote_version >= 27) {
 		mdfour_update(&m, (uchar *)tmpchunk, (len-i));
 	}
 
diff --git a/lib/mdfour.c b/lib/mdfour.c
index c7bc7abf..d8e86322 100644
--- a/lib/mdfour.c
+++ b/lib/mdfour.c
@@ -109,29 +109,53 @@ void mdfour_begin(struct mdfour *md)
 	md->C = 0x98badcfe;
 	md->D = 0x10325476;
 	md->totalN = 0;
+	md->totalN2 = 0;
 }
 
 
-static void mdfour_tail(unsigned char *in, int n)
+static void mdfour_tail(unsigned char *in, uint32 n)
 {
 	unsigned char buf[128];
 	uint32 M[16];
-	uint32 b;
-
-	m->totalN += n;
-
-	b = m->totalN * 8;
+	extern int remote_version;
+
+	/*
+	 * Count total number of bits, modulo 2^64
+	 */
+	m->totalN += n << 3;
+	if (m->totalN < (n << 3)) {
+		m->totalN2++;
+	}
+	m->totalN2 += n >> 29;
 
 	memset(buf, 0, 128);
 	if (n) memcpy(buf, in, n);
 	buf[n] = 0x80;
 
 	if (n <= 55) {
-		copy4(buf+56, b);
+		copy4(buf+56, m->totalN);
+		/*
+		 * Prior to protocol version 27 only the number of bits
+		 * modulo 2^32 was included.  MD4 requires the number
+		 * of bits modulo 2^64, which was fixed starting with
+		 * protocol version 27.
+		 */
+		if (remote_version >= 27) {
+			copy4(buf+60, m->totalN2);
+		}
 		copy64(M, buf);
 		mdfour64(M);
 	} else {
-		copy4(buf+120, b); 
+		copy4(buf+120, m->totalN); 
+		/*
+		 * Prior to protocol version 27 only the number of bits
+		 * modulo 2^32 was included.  MD4 requires the number
+		 * of bits modulo 2^64, which was fixed starting with
+		 * protocol version 27.
+		 */
+		if (remote_version >= 27) {
+			copy4(buf+124, m->totalN2); 
+		}
 		copy64(M, buf);
 		mdfour64(M);
 		copy64(M, buf+64);
@@ -139,20 +163,23 @@ static void mdfour_tail(unsigned char *in, int n)
 	}
 }
 
-void mdfour_update(struct mdfour *md, unsigned char *in, int n)
+void mdfour_update(struct mdfour *md, unsigned char *in, uint32 n)
 {
 	uint32 M[16];
 
-	if (n == 0) mdfour_tail(in, n);
-
 	m = md;
 
+	if (n == 0) mdfour_tail(in, n);
+
 	while (n >= 64) {
 		copy64(M, in);
 		mdfour64(M);
 		in += 64;
 		n -= 64;
-		m->totalN += 64;
+		m->totalN += 64 << 3;
+		if (m->totalN < 64 << 3) {
+			m->totalN2++;
+		}
 	}
 
 	if (n) mdfour_tail(in, n);
diff --git a/lib/mdfour.h b/lib/mdfour.h
index 2dd5527f..b0f3176f 100644
--- a/lib/mdfour.h
+++ b/lib/mdfour.h
@@ -21,11 +21,12 @@
 
 struct mdfour {
 	uint32 A, B, C, D;
-	uint32 totalN;
+	uint32 totalN;          /* bit count, lower 32 bits */
+	uint32 totalN2;         /* bit count, upper 32 bits */
 };
 
 void mdfour_begin(struct mdfour *md);
-void mdfour_update(struct mdfour *md, unsigned char *in, int n);
+void mdfour_update(struct mdfour *md, unsigned char *in, uint32 n);
 void mdfour_result(struct mdfour *md, unsigned char *out);
 void mdfour(unsigned char *out, unsigned char *in, int n);
 
-- 
2.34.1