Modify libpq's string-escaping routines to be aware of encoding considerations

and standard_conforming_strings.  The encoding changes are needed for proper
escaping in multibyte encodings, as per the SQL-injection vulnerabilities
noted in CVE-2006-2313 and CVE-2006-2314.  Concurrent fixes are being applied
to the server to ensure that it rejects queries that may have been corrupted
by attempted SQL injection, but this merely guarantees that unpatched clients
will fail rather than allow injection.  An actual fix requires changing the
client-side code.  While at it we have also fixed these routines to understand
about standard_conforming_strings, so that the upcoming changeover to SQL-spec
string syntax can be somewhat transparent to client code.

Since the existing API of PQescapeString and PQescapeBytea provides no way to
inform them which settings are in use, these functions are now deprecated in
favor of new functions PQescapeStringConn and PQescapeByteaConn.  The new
functions take the PGconn to which the string will be sent as an additional
parameter, and look inside the connection structure to determine what to do.
So as to provide some functionality for clients using the old functions,
libpq stores the latest encoding and standard_conforming_strings values
received from the backend in static variables, and the old functions consult
these variables.  This will work reliably in clients using only one Postgres
connection at a time, or even multiple connections if they all use the same
encoding and string syntax settings; which should cover many practical
scenarios.

Clients that use homebrew escaping methods, such as PHP's addslashes()
function or even hardwired regexp substitution, will require extra effort
to fix :-(.  It is strongly recommended that such code be replaced by use of
PQescapeStringConn/PQescapeByteaConn if at all feasible.

5 files changed, 172 insertions, 59 deletions

diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 0bdb55e1eae..318dc0168af 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-connect.c,v 1.213.2.5 2005/07/14 14:07:50 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-connect.c,v 1.213.2.6 2006/05/21 20:20:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1642,6 +1642,7 @@ PQsetenvPoll(PGconn *conn)
 						goto error_return;
 					}
 					conn->client_encoding = encoding;
+					PQ_static_client_encoding = conn->client_encoding;
 
 					/* Move on to setting the environment options */
 					conn->setenv_state = SETENV_STATE_OPTION_SEND;
@@ -1668,6 +1669,7 @@ PQsetenvPoll(PGconn *conn)
 							conn->client_encoding = PG_SQL_ASCII;
 						else
 							conn->client_encoding = pg_char_to_encoding(encoding);
+						PQ_static_client_encoding = conn->client_encoding;
 					}
 					else if (PQresultStatus(res) != PGRES_COMMAND_OK)
 					{
@@ -1857,6 +1859,7 @@ makeEmptyPGconn(void)
 	conn->status = CONNECTION_BAD;
 	conn->asyncStatus = PGASYNC_IDLE;
 	conn->setenv_state = SETENV_STATE_IDLE;
+	conn->client_encoding = PG_SQL_ASCII;
 	conn->notifyList = DLNewList();
 	conn->sock = -1;
 #ifdef USE_SSL
@@ -2763,6 +2766,7 @@ PQsetClientEncoding(PGconn *conn, const char *encoding)
 	{
 		/* change libpq internal encoding */
 		conn->client_encoding = pg_char_to_encoding(encoding);
+		PQ_static_client_encoding = conn->client_encoding;
 		status = 0;				/* everything is ok */
 	}
 	PQclear(res);
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index b5dc8de0a87..071c102d65d 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.122.2.2 2006/05/21 19:56:41 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.122.2.3 2006/05/21 20:20:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,6 +20,7 @@
 
 #include "libpq-fe.h"
 #include "libpq-int.h"
+#include "mb/pg_wchar.h"
 
 #ifdef WIN32
 #include "win32.h"
@@ -39,6 +40,12 @@ char	   *const pgresStatus[] = {
 	"PGRES_FATAL_ERROR"
 };
 
+/*
+ * static state needed by PQescapeString and PQescapeBytea; initialize to
+ * values that result in backward-compatible behavior
+ */
+int	PQ_static_client_encoding = PG_SQL_ASCII;
+static bool	static_std_strings = false;
 
 /* Note: DONOTICE macro will work if applied to either PGconn or PGresult */
 #define DONOTICE(conn,message) \
@@ -59,45 +66,80 @@ static int	getNotice(PGconn *conn);
 /* ---------------
  * Escaping arbitrary strings to get valid SQL strings/identifiers.
  *
- * Replaces "\\" with "\\\\" and "'" with "''".
+ * Replaces "'" with "''", and if not std_strings, replaces "\" with "\\".
  * length is the length of the buffer pointed to by
  * from.  The buffer at to must be at least 2*length + 1 characters
  * long.  A terminating NUL character is written.
  * ---------------
  */
-
-size_t
-PQescapeString(char *to, const char *from, size_t length)
+static size_t
+PQescapeStringInternal(PGconn *conn,
+					   char *to, const char *from, size_t length,
+					   int *error,
+					   int encoding, bool std_strings)
 {
 	const char *source = from;
 	char	   *target = to;
-	unsigned int remaining = length;
+	size_t		remaining = length;
+
+	if (error)
+		*error = 0;
 
-	while (remaining > 0)
+	while (remaining > 0 && *source != '\0')
 	{
-		switch (*source)
+		char	c = *source;
+		int		len;
+		int		i;
+
+		/* Fast path for plain ASCII */
+		if (!IS_HIGHBIT_SET(c))
 		{
-			case '\\':
-				*target = '\\';
-				target++;
-				*target = '\\';
-				/* target and remaining are updated below. */
-				break;
+			/* Apply quoting if needed */
+			if (c == '\'' ||
+				(c == '\\' && !std_strings))
+				*target++ = c;
+			/* Copy the character */
+			*target++ = c;
+			source++;
+			remaining--;
+			continue;
+		}
 
-			case '\'':
-				*target = '\'';
-				target++;
-				*target = '\'';
-				/* target and remaining are updated below. */
+		/* Slow path for possible multibyte characters */
+		len = pg_encoding_mblen(encoding, source);
+
+		/* Copy the character */
+		for (i = 0; i < len; i++)
+		{
+			if (remaining == 0 || *source == '\0')
 				break;
+			*target++ = *source++;
+			remaining--;
+		}
 
-			default:
-				*target = *source;
-				/* target and remaining are updated below. */
+		/*
+		 * If we hit premature end of string (ie, incomplete multibyte
+		 * character), try to pad out to the correct length with spaces.
+		 * We may not be able to pad completely, but we will always be able
+		 * to insert at least one pad space (since we'd not have quoted a
+		 * multibyte character).  This should be enough to make a string that
+		 * the server will error out on.
+		 */
+		if (i < len)
+		{
+			if (error)
+				*error = 1;
+			if (conn)
+				printfPQExpBuffer(&conn->errorMessage,
+						libpq_gettext("incomplete multibyte character\n"));
+			for (; i < len; i++)
+			{
+				if (((size_t) (target - to)) / 2 >= length)
+					break;
+				*target++ = ' ';
+			}
+			break;
 		}
-		source++;
-		target++;
-		remaining--;
 	}
 
 	/* Write the terminating NUL character. */
@@ -106,72 +148,109 @@ PQescapeString(char *to, const char *from, size_t length)
 	return target - to;
 }
 
+size_t
+PQescapeStringConn(PGconn *conn,
+				   char *to, const char *from, size_t length,
+				   int *error)
+{
+	if (!conn)
+	{
+		/* force empty-string result */
+		*to = '\0';
+		if (error)
+			*error = 1;
+		return 0;
+	}
+	return PQescapeStringInternal(conn, to, from, length, error,
+								  conn->client_encoding,
+								  static_std_strings);
+}
+
+size_t
+PQescapeString(char *to, const char *from, size_t length)
+{
+	return PQescapeStringInternal(NULL, to, from, length, NULL,
+								  PQ_static_client_encoding,
+								  static_std_strings);
+}
+
 /*
  *		PQescapeBytea	- converts from binary string to the
  *		minimal encoding necessary to include the string in an SQL
  *		INSERT statement with a bytea type column as the target.
  *
  *		The following transformations are applied
- *		'\0' == ASCII  0 == \\000
- *		'\'' == ASCII 39 == \'
- *		'\\' == ASCII 92 == \\\\
- *		anything < 0x20, or > 0x7e ---> \\ooo
- *                                      (where ooo is an octal expression)
+ *		'\0' == ASCII  0 == \000
+ *		'\'' == ASCII 39 == ''
+ *		'\\' == ASCII 92 == \\
+ *		anything < 0x20, or > 0x7e ---> \ooo
+ *										(where ooo is an octal expression)
+ *		If not std_strings, all backslashes sent to the output are doubled.
  */
-unsigned char *
-PQescapeBytea(unsigned char *bintext, size_t binlen, size_t *bytealen)
+static unsigned char *
+PQescapeByteaInternal(PGconn *conn,
+					  const unsigned char *from, size_t from_length,
+					  size_t *to_length, bool std_strings)
 {
-	unsigned char *vp;
+	const unsigned char *vp;
 	unsigned char *rp;
 	unsigned char *result;
 	size_t		i;
 	size_t		len;
+	size_t		bslash_len = (std_strings ? 1 : 2);
 
 	/*
 	 * empty string has 1 char ('\0')
 	 */
 	len = 1;
 
-	vp = bintext;
-	for (i = binlen; i > 0; i--, vp++)
+	vp = from;
+	for (i = from_length; i > 0; i--, vp++)
 	{
 		if (*vp < 0x20 || *vp > 0x7e)
-			len += 5;			/* '5' is for '\\ooo' */
+			len += bslash_len + 3;
 		else if (*vp == '\'')
 			len += 2;
 		else if (*vp == '\\')
-			len += 4;
+			len += bslash_len + bslash_len;
 		else
 			len++;
 	}
 
+	*to_length = len;
 	rp = result = (unsigned char *) malloc(len);
 	if (rp == NULL)
+	{
+		if (conn)
+			printfPQExpBuffer(&conn->errorMessage,
+							  libpq_gettext("out of memory\n"));
 		return NULL;
+	}
 
-	vp = bintext;
-	*bytealen = len;
-
-	for (i = binlen; i > 0; i--, vp++)
+	vp = from;
+	for (i = from_length; i > 0; i--, vp++)
 	{
 		if (*vp < 0x20 || *vp > 0x7e)
 		{
-			(void) sprintf(rp, "\\\\%03o", *vp);
-			rp += 5;
+			if (!std_strings)
+				*rp++ = '\\';
+			(void) sprintf((char *) rp, "\\%03o", *vp);
+			rp += 4;
 		}
 		else if (*vp == '\'')
 		{
-			rp[0] = '\'';
-			rp[1] = '\'';
-			rp += 2;
+			*rp++ = '\'';
+			*rp++ = '\'';
 		}
 		else if (*vp == '\\')
 		{
-			rp[0] = '\\';
-			rp[1] = '\\';
-			rp[2] = '\\';
-			rp[3] = '\\';
-			rp += 4;
+			if (!std_strings)
+			{
+				*rp++ = '\\';
+				*rp++ = '\\';
+			}
+			*rp++ = '\\';
+			*rp++ = '\\';
 		}
 		else
 			*rp++ = *vp;
@@ -181,12 +260,31 @@ PQescapeBytea(unsigned char *bintext, size_t binlen, size_t *bytealen)
 	return result;
 }
 
+unsigned char *
+PQescapeByteaConn(PGconn *conn,
+				  const unsigned char *from, size_t from_length,
+				  size_t *to_length)
+{
+	if (!conn)
+		return NULL;
+	return PQescapeByteaInternal(conn, from, from_length, to_length,
+								 static_std_strings);
+}
+
+unsigned char *
+PQescapeBytea(unsigned char *from, size_t from_length, size_t *to_length)
+{
+	return PQescapeByteaInternal(NULL, from, from_length, to_length,
+								 static_std_strings);
+}
+
+
 /*
  *		PQunescapeBytea - converts the null terminated string representation
  *		of a bytea, strtext, into binary, filling a buffer. It returns a
  *		pointer to the buffer which is NULL on error, and the size of the
  *		buffer in retbuflen. The pointer may subsequently be used as an
- *		argument to the function free(3). It is the reverse of PQescapeBytea.
+ *		argument to the function PQfreemem.
  *
  *		The following transformations are reversed:
  *		'\0' == ASCII  0 == \000
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
index 49045d37b9d..188dbf579c9 100644
--- a/src/interfaces/libpq/libpq-fe.h
+++ b/src/interfaces/libpq/libpq-fe.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: libpq-fe.h,v 1.86 2002/09/04 20:31:47 momjian Exp $
+ * $Id: libpq-fe.h,v 1.86.2.1 2006/05/21 20:20:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -248,12 +248,18 @@ extern PQnoticeProcessor PQsetNoticeProcessor(PGconn *conn,
 /* === in fe-exec.c === */
 
 /* Quoting strings before inclusion in queries. */
-extern size_t PQescapeString(char *to, const char *from, size_t length);
-extern unsigned char *PQescapeBytea(unsigned char *bintext, size_t binlen,
-			  size_t *bytealen);
+extern size_t PQescapeStringConn(PGconn *conn,
+								 char *to, const char *from, size_t length,
+								 int *error);
+extern unsigned char *PQescapeByteaConn(PGconn *conn,
+				  const unsigned char *from, size_t from_length,
+				  size_t *to_length);
 extern unsigned char *PQunescapeBytea(unsigned char *strtext,
 				size_t *retbuflen);
-
+/* These forms are deprecated! */
+extern size_t PQescapeString(char *to, const char *from, size_t length);
+extern unsigned char *PQescapeBytea(unsigned char *from, size_t from_length,
+			  size_t *to_length);
 
 /* Simple synchronous query */
 extern PGresult *PQexec(PGconn *conn, const char *query);
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index cde2b2d2b05..1a8360c751c 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: libpq-int.h,v 1.60 2002/10/16 02:55:30 momjian Exp $
+ * $Id: libpq-int.h,v 1.60.2.1 2006/05/21 20:20:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -301,6 +301,9 @@ struct pg_conn
  */
 extern char *const pgresStatus[];
 
+/* Added for PQescapeString fix */
+extern int	PQ_static_client_encoding;
+
 /* ----------------
  * Internal functions of libpq
  * Functions declared here need to be visible across files of libpq,
diff --git a/src/interfaces/libpq/libpqdll.def b/src/interfaces/libpq/libpqdll.def
index 524a7468e8a..78269f89fa4 100644
--- a/src/interfaces/libpq/libpqdll.def
+++ b/src/interfaces/libpq/libpqdll.def
@@ -93,3 +93,5 @@ EXPORTS
 	appendPQExpBuffer	@ 91
 	pg_encoding_to_char	@ 92
 	pg_utf_mblen		@ 93
+        PQescapeStringConn      @ 126
+        PQescapeByteaConn       @ 127