res/res_config_odbc: Fix improper escaping of backslashes with MySQL

When escaping backslashes with MySQL, the proper way to escape the characters
in a LIKE clause is to escape the '\' four times, i.e., '\\\\'. To quote the
MySQL manual:

"Because MySQL uses C escape syntax in strings (for example, “\n” to represent
a newline character), you must double any “\” that you use in LIKE strings.
For example, to search for “\n”, specify it as “\\n”. To search for “\”,
specify it as “\\\\”; this is because the backslashes are stripped once by the
parser and again when the pattern match is made, leaving a single backslash to
be matched against."

ASTERISK-24808 #close
Reported by: Javier Acosta
patches:
  res_config_odbc.diff uploaded by Javier Acosta (License 6690)
........

Merged revisions 432720 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 432721 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@432722 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_config_odbc.c

@@ -198,11 +198,11 @@ static struct ast_variable *realtime_odbc(const char *database, const char *tabl
 
 	op = !strchr(field->name, ' ') ? " =" : "";
 	snprintf(sql, sizeof(sql), "SELECT * FROM %s WHERE %s%s ?%s", table, field->name, op,
-		strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\'" : "");
+		strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\\\'" : "");
 	while ((field = field->next)) {
 		op = !strchr(field->name, ' ') ? " =" : "";
 		snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), " AND %s%s ?%s", field->name, op,
-			strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\'" : "");
+			strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\\\'" : "");
 	}
 
 	if (ast_string_field_init(&cps, 256)) {
@@ -360,11 +360,11 @@ static struct ast_config *realtime_multi_odbc(const char *database, const char *
 
 	op = !strchr(field->name, ' ') ? " =" : "";
 	snprintf(sql, sizeof(sql), "SELECT * FROM %s WHERE %s%s ?%s", table, field->name, op,
-		strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\'" : "");
+		strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\\\'" : "");
 	while ((field = field->next)) {
 		op = !strchr(field->name, ' ') ? " =" : "";
 		snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), " AND %s%s ?%s", field->name, op,
-			strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\'" : "");
+			strcasestr(field->name, "LIKE") && !ast_odbc_backslash_is_escape(obj) ? " ESCAPE '\\\\'" : "");
 	}
 
 	snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), " ORDER BY %s", initfield);