5 files changed, 229 insertions, 56 deletions

diff --git a/ChangeLog b/ChangeLog
index 3847553dc..f991fe7eb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -54,6 +54,10 @@
    - djm@cvs.openbsd.org 2004/10/29 22:53:56
      [clientloop.c misc.h readpass.c ssh-agent.c]
      factor out common permission-asking code to separate function; ok markus@
+   - djm@cvs.openbsd.org 2004/10/29 23:56:17
+     [bufaux.c bufaux.h buffer.c buffer.h]
+     introduce a new buffer API that returns an error rather than fatal()ing
+     when presented with bad data; ok markus@
 
 20041102
  - (dtucker) [configure.ac includes.h] Bug #947: Fix compile error on HP-UX
@@ -1833,4 +1837,4 @@
    - (djm) Trim deprecated options from INSTALL. Mention UsePAM
    - (djm) Fix quote handling in sftp; Patch from admorten AT umich.edu
 
-$Id: ChangeLog,v 1.3576 2004/11/05 09:38:03 dtucker Exp $
+$Id: ChangeLog,v 1.3577 2004/11/05 09:41:24 dtucker Exp $
diff --git a/bufaux.c b/bufaux.c
index bf148316d..cbe77d5ae 100644
--- a/bufaux.c
+++ b/bufaux.c
@@ -37,7 +37,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: bufaux.c,v 1.32 2004/02/23 15:12:46 markus Exp $");
+RCSID("$OpenBSD: bufaux.c,v 1.33 2004/10/29 23:56:17 djm Exp $");
 
 #include <openssl/bn.h>
 #include "bufaux.h"
@@ -49,8 +49,8 @@ RCSID("$OpenBSD: bufaux.c,v 1.32 2004/02/23 15:12:46 markus Exp $");
  * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
  * by (bits+7)/8 bytes of binary data, msb first.
  */
-void
-buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
+int
+buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value)
 {
         int bits = BN_num_bits(value);
         int bin_size = (bits + 7) / 8;
@@ -60,9 +60,11 @@ buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
 
         /* Get the value of in binary */
         oi = BN_bn2bin(value, buf);
-        if (oi != bin_size)
-                fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
+        if (oi != bin_size) {
+                error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d",
                     oi, bin_size);
+                return (-1);
+        }
 
         /* Store the number of bits in the buffer in two bytes, msb first. */
         PUT_16BIT(msg, bits);
@@ -72,36 +74,63 @@ buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
 
         memset(buf, 0, bin_size);
         xfree(buf);
+
+        return (0);
+}
+
+void
+buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
+{
+        if (buffer_put_bignum_ret(buffer, value) == -1)
+                fatal("buffer_put_bignum: buffer error");
 }
 
 /*
  * Retrieves an BIGNUM from the buffer.
  */
-void
-buffer_get_bignum(Buffer *buffer, BIGNUM *value)
+int
+buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value)
 {
         u_int bits, bytes;
         u_char buf[2], *bin;
 
         /* Get the number for bits. */
-        buffer_get(buffer, (char *) buf, 2);
+        if (buffer_get_ret(buffer, (char *) buf, 2) == -1) {
+                error("buffer_get_bignum_ret: invalid length");
+                return (-1);
+        }
         bits = GET_16BIT(buf);
         /* Compute the number of binary bytes that follow. */
         bytes = (bits + 7) / 8;
-        if (bytes > 8 * 1024)
-                fatal("buffer_get_bignum: cannot handle BN of size %d", bytes);
-        if (buffer_len(buffer) < bytes)
-                fatal("buffer_get_bignum: input buffer too small");
+        if (bytes > 8 * 1024) {
+                error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes);
+                return (-1);
+        }
+        if (buffer_len(buffer) < bytes) {
+                error("buffer_get_bignum_ret: input buffer too small");
+                return (-1);
+        }
         bin = buffer_ptr(buffer);
         BN_bin2bn(bin, bytes, value);
-        buffer_consume(buffer, bytes);
+        if (buffer_consume_ret(buffer, bytes) == -1) {
+                error("buffer_get_bignum_ret: buffer_consume failed");
+                return (-1);
+        }
+        return (0);
+}
+
+void
+buffer_get_bignum(Buffer *buffer, BIGNUM *value)
+{
+        if (buffer_get_bignum_ret(buffer, value) == -1)
+                fatal("buffer_get_bignum: buffer error");
 }
 
 /*
  * Stores an BIGNUM in the buffer in SSH2 format.
  */
-void
-buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
+int
+buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
 {
         u_int bytes;
         u_char *buf;
@@ -110,69 +139,140 @@ buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
 
         if (BN_is_zero(value)) {
                 buffer_put_int(buffer, 0);
-                return;
+                return 0;
+        }
+        if (value->neg) {
+                error("buffer_put_bignum2_ret: negative numbers not supported");
+                return (-1);
         }
-        if (value->neg)
-                fatal("buffer_put_bignum2: negative numbers not supported");
         bytes = BN_num_bytes(value) + 1; /* extra padding byte */
-        if (bytes < 2)
-                fatal("buffer_put_bignum2: BN too small");
+        if (bytes < 2) {
+                error("buffer_put_bignum2_ret: BN too small");
+                return (-1);
+        }
         buf = xmalloc(bytes);
         buf[0] = '\0';
         /* Get the value of in binary */
         oi = BN_bn2bin(value, buf+1);
-        if (oi != bytes-1)
-                fatal("buffer_put_bignum2: BN_bn2bin() failed: "
+        if (oi != bytes-1) {
+                error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
                     "oi %d != bin_size %d", oi, bytes);
+                xfree(buf);
+                return (-1);
+        }
         hasnohigh = (buf[1] & 0x80) ? 0 : 1;
         buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
         memset(buf, 0, bytes);
         xfree(buf);
+        return (0);
 }
 
 void
-buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
+buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
+{
+        if (buffer_put_bignum2_ret(buffer, value) == -1)
+                fatal("buffer_put_bignum2: buffer error");
+}
+
+int
+buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
 {
         u_int len;
-        u_char *bin = buffer_get_string(buffer, &len);
+        u_char *bin;
+        
+        if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
+                error("buffer_get_bignum2_ret: invalid bignum");
+                return (-1);
+        }
 
-        if (len > 0 && (bin[0] & 0x80))
-                fatal("buffer_get_bignum2: negative numbers not supported");
-        if (len > 8 * 1024)
-                fatal("buffer_get_bignum2: cannot handle BN of size %d", len);
+        if (len > 0 && (bin[0] & 0x80)) {
+                error("buffer_get_bignum2_ret: negative numbers not supported");
+                return (-1);
+        }
+        if (len > 8 * 1024) {
+                error("buffer_get_bignum2_ret: cannot handle BN of size %d", len);
+                return (-1);
+        }
         BN_bin2bn(bin, len, value);
         xfree(bin);
+        return (0);
+}
+
+void
+buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
+{
+        if (buffer_get_bignum2_ret(buffer, value) == -1)
+                fatal("buffer_get_bignum2: buffer error");
 }
 
 /*
  * Returns integers from the buffer (msb first).
  */
 
+int
+buffer_get_short_ret(u_short *ret, Buffer *buffer)
+{
+        u_char buf[2];
+
+        if (buffer_get_ret(buffer, (char *) buf, 2) == -1)
+                return (-1);
+        *ret = GET_16BIT(buf);
+        return (0);
+}
+
 u_short
 buffer_get_short(Buffer *buffer)
 {
-        u_char buf[2];
+        u_short ret;
+
+        if (buffer_get_short_ret(&ret, buffer) == -1)
+                fatal("buffer_get_short: buffer error");
 
-        buffer_get(buffer, (char *) buf, 2);
-        return GET_16BIT(buf);
+        return (ret);
+}
+
+int
+buffer_get_int_ret(u_int *ret, Buffer *buffer)
+{
+        u_char buf[4];
+
+        if (buffer_get_ret(buffer, (char *) buf, 4) == -1)
+                return (-1);
+        *ret = GET_32BIT(buf);
+        return (0);
 }
 
 u_int
 buffer_get_int(Buffer *buffer)
 {
-        u_char buf[4];
+        u_int ret;
+
+        if (buffer_get_int_ret(&ret, buffer) == -1)
+                fatal("buffer_get_int: buffer error");
+
+        return (ret);
+}
 
-        buffer_get(buffer, (char *) buf, 4);
-        return GET_32BIT(buf);
+int
+buffer_get_int64_ret(u_int64_t *ret, Buffer *buffer)
+{
+        u_char buf[8];
+
+        if (buffer_get_ret(buffer, (char *) buf, 8) == -1)
+                return (-1);
+        *ret = GET_64BIT(buf);
+        return (0);
 }
 
 u_int64_t
 buffer_get_int64(Buffer *buffer)
 {
-        u_char buf[8];
+        u_int64_t ret;
 
-        buffer_get(buffer, (char *) buf, 8);
-        return GET_64BIT(buf);
+        if (buffer_get_int64_ret(&ret, buffer) == -1)
+                fatal("buffer_get_int: buffer error");
+
+        return (ret);
 }
 
 /*
@@ -214,25 +314,41 @@ buffer_put_int64(Buffer *buffer, u_int64_t value)
  * to the returned string, and is not counted in length.
  */
 void *
-buffer_get_string(Buffer *buffer, u_int *length_ptr)
+buffer_get_string_ret(Buffer *buffer, u_int *length_ptr)
 {
         u_char *value;
         u_int len;
 
         /* Get the length. */
         len = buffer_get_int(buffer);
-        if (len > 256 * 1024)
-                fatal("buffer_get_string: bad string length %u", len);
+        if (len > 256 * 1024) {
+                error("buffer_get_string_ret: bad string length %u", len);
+                return (NULL);
+        }
         /* Allocate space for the string.  Add one byte for a null character. */
         value = xmalloc(len + 1);
         /* Get the string. */
-        buffer_get(buffer, value, len);
+        if (buffer_get_ret(buffer, value, len) == -1) {
+                error("buffer_get_string_ret: buffer_get failed");
+                xfree(value);
+                return (NULL);
+        }
         /* Append a null character to make processing easier. */
         value[len] = 0;
         /* Optionally return the length of the string. */
         if (length_ptr)
                 *length_ptr = len;
-        return value;
+        return (value);
+}
+
+void *
+buffer_get_string(Buffer *buffer, u_int *length_ptr)
+{
+        void *ret;
+
+        if ((ret = buffer_get_string_ret(buffer, length_ptr)) == NULL)
+                fatal("buffer_get_string: buffer error");
+        return (ret);
 }
 
 /*
@@ -256,11 +372,22 @@ buffer_put_cstring(Buffer *buffer, const char *s)
  * Returns a character from the buffer (0 - 255).
  */
 int
+buffer_get_char_ret(char *ret, Buffer *buffer)
+{
+        if (buffer_get_ret(buffer, ret, 1) == -1) {
+                error("buffer_get_char_ret: buffer_get_ret failed");
+                return (-1);
+        }
+        return (0);
+}
+
+int
 buffer_get_char(Buffer *buffer)
 {
         char ch;
 
-        buffer_get(buffer, &ch, 1);
+        if (buffer_get_char_ret(&ch, buffer) == -1)
+                fatal("buffer_get_char: buffer error");
         return (u_char) ch;
 }
 
diff --git a/bufaux.h b/bufaux.h
index 61c72e353..e30911ddc 100644
--- a/bufaux.h
+++ b/bufaux.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: bufaux.h,v 1.19 2003/11/10 16:23:41 jakob Exp $       */
+/*      $OpenBSD: bufaux.h,v 1.20 2004/10/29 23:56:17 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -42,4 +42,14 @@ void	buffer_put_cstring(Buffer *, const char *);
 #define buffer_skip_string(b) \
     do { u_int l = buffer_get_int(b); buffer_consume(b, l); } while(0)
 
+int     buffer_put_bignum_ret(Buffer *, const BIGNUM *);
+int     buffer_get_bignum_ret(Buffer *, BIGNUM *);
+int     buffer_put_bignum2_ret(Buffer *, const BIGNUM *);
+int     buffer_get_bignum2_ret(Buffer *, BIGNUM *);
+int     buffer_get_short_ret(u_short *, Buffer *);
+int     buffer_get_int_ret(u_int *, Buffer *);
+int     buffer_get_int64_ret(u_int64_t *, Buffer *);
+void    *buffer_get_string_ret(Buffer *, u_int *);
+int     buffer_get_char_ret(char *, Buffer *);
+
 #endif                          /* BUFAUX_H */
diff --git a/buffer.c b/buffer.c
index 9217cb269..1a25004ba 100644
--- a/buffer.c
+++ b/buffer.c
@@ -12,7 +12,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: buffer.c,v 1.21 2003/11/21 11:57:03 djm Exp $");
+RCSID("$OpenBSD: buffer.c,v 1.22 2004/10/29 23:56:17 djm Exp $");
 
 #include "xmalloc.h"
 #include "buffer.h"
@@ -126,34 +126,62 @@ buffer_len(Buffer *buffer)
 
 /* Gets data from the beginning of the buffer. */
 
-void
-buffer_get(Buffer *buffer, void *buf, u_int len)
+int
+buffer_get_ret(Buffer *buffer, void *buf, u_int len)
 {
-        if (len > buffer->end - buffer->offset)
-                fatal("buffer_get: trying to get more bytes %d than in buffer %d",
+        if (len > buffer->end - buffer->offset) {
+                error("buffer_get_ret: trying to get more bytes %d than in buffer %d",
                     len, buffer->end - buffer->offset);
+                return (-1);
+        }
         memcpy(buf, buffer->buf + buffer->offset, len);
         buffer->offset += len;
+        return (0);
+}
+
+void
+buffer_get(Buffer *buffer, void *buf, u_int len)
+{
+        if (buffer_get_ret(buffer, buf, len) == -1)
+                fatal("buffer_get: buffer error");
 }
 
 /* Consumes the given number of bytes from the beginning of the buffer. */
 
+int
+buffer_consume_ret(Buffer *buffer, u_int bytes)
+{
+        if (bytes > buffer->end - buffer->offset) {
+                error("buffer_consume_ret: trying to get more bytes than in buffer");
+                return (-1);
+        }
+        buffer->offset += bytes;
+        return (0);
+}
+
 void
 buffer_consume(Buffer *buffer, u_int bytes)
 {
-        if (bytes > buffer->end - buffer->offset)
-                fatal("buffer_consume: trying to get more bytes than in buffer");
-        buffer->offset += bytes;
+        if (buffer_consume_ret(buffer, bytes) == -1)
+                fatal("buffer_consume: buffer error");
 }
 
 /* Consumes the given number of bytes from the end of the buffer. */
 
+int
+buffer_consume_end_ret(Buffer *buffer, u_int bytes)
+{
+        if (bytes > buffer->end - buffer->offset)
+                return (-1);
+        buffer->end -= bytes;
+        return (0);
+}
+
 void
 buffer_consume_end(Buffer *buffer, u_int bytes)
 {
-        if (bytes > buffer->end - buffer->offset)
+        if (buffer_consume_end_ret(buffer, bytes) == -1)
                 fatal("buffer_consume_end: trying to get more bytes than in buffer");
-        buffer->end -= bytes;
 }
 
 /* Returns a pointer to the first used byte in the buffer. */
diff --git a/buffer.h b/buffer.h
index 5e4c41244..9c09d4f43 100644
--- a/buffer.h
+++ b/buffer.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: buffer.h,v 1.11 2002/03/04 17:27:39 stevesk Exp $     */
+/*      $OpenBSD: buffer.h,v 1.12 2004/10/29 23:56:17 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -40,4 +40,8 @@ void	 buffer_consume_end(Buffer *, u_int);
 
 void     buffer_dump(Buffer *);
 
+int      buffer_get_ret(Buffer *, void *, u_int);
+int      buffer_consume_ret(Buffer *, u_int);
+int      buffer_consume_end_ret(Buffer *, u_int);
+
 #endif                          /* BUFFER_H */