From 8b98aa2679a8ef3f107b656e0f1b927d4604a054 Mon Sep 17 00:00:00 2001
From: changbai <changbai@pinduoduo.com>
Date: Thu, 19 Aug 2021 19:53:33 +0800
Subject: [PATCH] bugfix: data size calculation and data range check

1. Data size use two bytes to store size, so it should used data[offset] << 8
   | data[offset + 1] to calculate size
2. In some user generated ipdb database, data offset 0 has data too
---
 ipdb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/ipdb.c b/ipdb.c
index 9468a29..d9e9ff1 100644
--- a/ipdb.c
+++ b/ipdb.c
@@ -144,7 +144,7 @@ int ipdb_resolve(ipdb_reader *reader, int node, const char **bytes) {
         return ErrDatabaseError;
     }
 
-    int size = (reader->data[resolved] << 8) | reader->data[resolved + 2];
+    int size = (reader->data[resolved] << 8) | reader->data[resolved + 1];
     if ((resolved + 2 + size) > reader->data_size) {
         return ErrDatabaseError;
     }
@@ -162,7 +162,7 @@ int ipdb_search(ipdb_reader *reader, const u_char *ip, int bit_count, int *node)
     }
 
     for (int i = 0; i < bit_count; ++i) {
-        if (*node > reader->meta->node_count) {
+        if (*node >= reader->meta->node_count) {
             break;
         }
 
@@ -170,7 +170,7 @@ int ipdb_search(ipdb_reader *reader, const u_char *ip, int bit_count, int *node)
                                ((0xFF & ((int) ip[i >> 3])) >> (unsigned int) (7 - (i % 8))) & 1);
     }
 
-    if (*node > reader->meta->node_count) {
+    if (*node >= reader->meta->node_count) {
         return ErrNoErr;
     }
     return ErrDataNotExists;