diff --git a/binding/c/main.c b/binding/c/main.c
index 8a2219e..9270260 100644
--- a/binding/c/main.c
+++ b/binding/c/main.c
@@ -199,7 +199,7 @@ void test_bench(int argc, char *argv[]) {
     FILE *handle;
     char line[1024] = {'\0'}, sip_str[16] = {'\0'}, eip_str[16] = {'\0'};
     char src_region[512] = {'\0'}, region_buffer[512] = {'\0'};
-    unsigned int sip, eip, mip, ip_list[5];
+    unsigned int sip, eip, ip_list[2];
     int count = 0, took;
     long s_time, t_time, c_time = 0;
     searcher_test_t test;
@@ -283,13 +283,9 @@ void test_bench(int argc, char *argv[]) {
             return;
         }
 
-        mip = xdb_mip(sip, eip);
         ip_list[0] = sip;
-        ip_list[1] = xdb_mip(sip, mip);
-        ip_list[2] = mip;
-        ip_list[3] = xdb_mip(mip, eip);
-        ip_list[4] = eip;
-        for (i = 0; i < 5; i++) {
+        ip_list[1] = eip;
+        for (i = 0; i < 2; i++) {
             t_time = xdb_now();
             err = xdb_search(&test.searcher, ip_list[i], region_buffer, sizeof(region_buffer));
             if (err != 0) {
diff --git a/binding/c/test_util b/binding/c/test_util
index 625cdc9..bc93a29 100755
Binary files a/binding/c/test_util and b/binding/c/test_util differ
diff --git a/binding/c/xdb_api.h b/binding/c/xdb_api.h
index 22b1d5e..21e28d3 100644
--- a/binding/c/xdb_api.h
+++ b/binding/c/xdb_api.h
@@ -37,8 +37,38 @@
 // cache of vector_index_row × vector_index_rows × vector_index_size
 #define xdb_vector_index_length 524288
 
+// --- xdb util functions
 
-// --- buffer load util functions
+// get the current time in microseconds
+XDB_PUBLIC(long) xdb_now();
+
+// get unsigned long (4bytes) from a specified buffer start from the specified offset with little-endian
+XDB_PUBLIC(unsigned int) xdb_le_get_uint32(const char *, int);
+
+// get unsigned short (2bytes) from a specified buffer start from the specified offset with little-endian
+XDB_PUBLIC(int) xdb_le_get_uint16(const char *, int);
+
+// check the specified string ip and convert it to an unsigned int
+XDB_PUBLIC(int) xdb_check_ip(const char *, unsigned int *);
+
+// unsigned int ip to string ip
+XDB_PUBLIC(void) xdb_long2ip(unsigned int, char *);
+
+
+// parse the specified IP address to byte array
+XDB_PUBLIC(int) xdb_parse_ip(const char *, const char *, size_t);
+
+// convert a specified ip bytes to humen-readable string
+XDB_PUBLIC(int) xdb_ip_to_string(const char *, size_t);
+
+// compare the specified ip bytes with another ip bytes in the specified buff from offset.
+// returns: -1 if ip1 < ip2, 1 if ip1 > ip2 or 0
+XDB_PUBLIC(int) xdb_ip_sub_compare(const char *, const char *, int, size_t);
+
+// --- END xdb utils
+
+
+// --- xdb buffer functions
 
 // use the following buffer struct to wrap the binary buffer data
 // since the buffer data could not be operated with the string API.
@@ -48,6 +78,10 @@ struct xdb_header {
     unsigned int created_at;
     unsigned int start_index_ptr;
     unsigned int end_index_ptr;
+    
+    // since 3.0+ with IPv6 supporting
+    unsigned short ip_version;
+    unsigned short runtime_ptr_bytes;
 
     // the original buffer
     unsigned int length;
@@ -89,7 +123,9 @@ XDB_PUBLIC(xdb_content_t *) xdb_load_content_from_file(const char *);
 
 XDB_PUBLIC(void) xdb_free_content(void *);
 
-// --- End buffer load
+// --- End xdb buffer
+
+// --- xdb searcher api
 
 // xdb searcher structure
 struct xdb_searcher_entry {
@@ -126,24 +162,6 @@ XDB_PUBLIC(int) xdb_search(xdb_searcher_t *, unsigned int, char *, size_t);
 
 XDB_PUBLIC(int) xdb_get_io_count(xdb_searcher_t *);
 
-
-// get unsigned long (4bytes) from a specified buffer start from the specified offset with little-endian
-XDB_PUBLIC(unsigned int) xdb_get_uint(const char *, int);
-
-// get unsigned short (2bytes) from a specified buffer start from the specified offset with little-endian
-XDB_PUBLIC(int) xdb_get_ushort(const char *, int);
-
-// check the specified string ip and convert it to an unsigned int
-XDB_PUBLIC(int) xdb_check_ip(const char *, unsigned int *);
-
-// unsigned int ip to string ip
-XDB_PUBLIC(void) xdb_long2ip(unsigned int, char *);
-
-// get the middle ip of a and b
-XDB_PUBLIC(unsigned int) xdb_mip(unsigned long, unsigned long);
-
-// get the current time in microseconds
-XDB_PUBLIC(long) xdb_now();
-
+// --- END xdb searcher api
 
 #endif // C_IP2REGION_XDB_H
diff --git a/binding/c/xdb_searcher.c b/binding/c/xdb_searcher.c
index 7ad4d16..b372e87 100644
--- a/binding/c/xdb_searcher.c
+++ b/binding/c/xdb_searcher.c
@@ -79,19 +79,19 @@ XDB_PUBLIC(int) xdb_search(xdb_searcher_t *xdb, unsigned int ip, char *region_bu
     il1 = ((int) (ip >> 16)) & 0xFF;
     idx = il0 * xdb_vector_index_cols * xdb_vector_index_size + il1 * xdb_vector_index_size;
     if (xdb->v_index != NULL) {
-        s_ptr = xdb_get_uint(xdb->v_index->buffer, idx);
-        e_ptr = xdb_get_uint(xdb->v_index->buffer, idx + 4);
+        s_ptr = xdb_le_get_uint32(xdb->v_index->buffer, idx);
+        e_ptr = xdb_le_get_uint32(xdb->v_index->buffer, idx + 4);
     } else if (xdb->content != NULL) {
-        s_ptr = xdb_get_uint(xdb->content->buffer, xdb_header_info_length + idx);
-        e_ptr = xdb_get_uint(xdb->content->buffer, xdb_header_info_length + idx + 4);
+        s_ptr = xdb_le_get_uint32(xdb->content->buffer, xdb_header_info_length + idx);
+        e_ptr = xdb_le_get_uint32(xdb->content->buffer, xdb_header_info_length + idx + 4);
     } else {
         err = read(xdb, xdb_header_info_length + idx, vector_buffer, sizeof(vector_buffer));
         if (err != 0) {
             return 10 + err;
         }
 
-        s_ptr = xdb_get_uint(vector_buffer, 0);
-        e_ptr = xdb_get_uint(vector_buffer, 4);
+        s_ptr = xdb_le_get_uint32(vector_buffer, 0);
+        e_ptr = xdb_le_get_uint32(vector_buffer, 4);
     }
 
     // printf("s_ptr=%u, e_ptr=%u\n", s_ptr, e_ptr);
@@ -109,16 +109,16 @@ XDB_PUBLIC(int) xdb_search(xdb_searcher_t *xdb, unsigned int ip, char *region_bu
         }
 
         // decode the data fields as needed
-        sip = xdb_get_uint(segment_buffer, 0);
+        sip = xdb_le_get_uint32(segment_buffer, 0);
         if (ip < sip) {
             h = m - 1;
         } else {
-            eip = xdb_get_uint(segment_buffer, 4);
+            eip = xdb_le_get_uint32(segment_buffer, 4);
             if (ip > eip) {
                 l = m + 1;
             } else {
-                data_len = xdb_get_ushort(segment_buffer, 8);
-                data_ptr = xdb_get_uint(segment_buffer, 10);
+                data_len = xdb_le_get_uint16(segment_buffer, 8);
+                data_ptr = xdb_le_get_uint32(segment_buffer, 10);
                 break;
             }
         }
diff --git a/binding/c/xdb_util.c b/binding/c/xdb_util.c
index 2d6c9e9..2c0f034 100644
--- a/binding/c/xdb_util.c
+++ b/binding/c/xdb_util.c
@@ -35,6 +35,82 @@ XDB_PRIVATE(int) gettimeofday(struct timeval* tp, void* tzp) {
 }
 #endif
 
+XDB_PUBLIC(long) xdb_now() {
+    struct timeval c_time;
+    gettimeofday(&c_time, NULL);
+    return c_time.tv_sec * (int)1e6 + c_time.tv_usec;
+}
+
+XDB_PUBLIC(unsigned int) xdb_le_get_uint32(const char *buffer, int offset) {
+    return (
+        ((buffer[offset  ]) & 0x000000FF) |
+        ((buffer[offset+1] <<  8) & 0x0000FF00) |
+        ((buffer[offset+2] << 16) & 0x00FF0000) |
+        ((buffer[offset+3] << 24) & 0xFF000000)
+    );
+}
+
+XDB_PUBLIC(int) xdb_le_get_uint16(const char *buffer, int offset) {
+    return (
+        ((buffer[offset  ]) & 0x000000FF) |
+        ((buffer[offset+1] << 8) & 0x0000FF00)
+    );
+}
+
+// string ip to unsigned int
+static int shiftIndex[4] = {24, 16, 8, 0};
+XDB_PUBLIC(int) xdb_check_ip(const char *src_ip, unsigned int *dst_ip) {
+    char c;
+    int i, n, ip = 0;
+    const char *ptr = src_ip;
+    for (i = 0; i < 4; i++) {
+        n = 0;
+        while (1) {
+            c = *ptr;
+            ptr++;
+            if (c >= '0' && c <= '9') {
+                n *= 10;
+                n += c - '0';
+            } else if ((i < 3 && c == '.') || i == 3) {
+                // stopping at the '.' but ignore the tailing chars
+                // after the 3rd one (auto clean the tailing none-integer ?).
+                break;
+            } else {
+                return 1;
+            }
+        }
+
+        if (n > 0xFF) {
+            return 2;
+        }
+
+        ip |= (n << shiftIndex[i]);
+    }
+
+    *dst_ip = ip;
+    return 0;
+}
+
+// unsigned int ip to string ip
+XDB_PUBLIC(void) xdb_long2ip(unsigned int ip, char *buffer) {
+    sprintf(buffer, "%d.%d.%d.%d", (ip >> 24) & 0xFF, (ip >> 16) & 0xFF, (ip >> 8) & 0xFF, ip & 0xFF);
+}
+
+XDB_PUBLIC(int) xdb_parse_ip(const char *ip, const char *buffer, size_t length) {
+    return 0;
+}
+
+XDB_PUBLIC(int) xdb_ip_to_string(const char *bytes, size_t length) {
+    return 0;
+}
+
+XDB_PUBLIC(int) xdb_ip_sub_compare(const char *ip1, const char *buffer, int offset, size_t length) {
+    return 0;
+}
+
+
+// --- xdb buffer function implementations
+
 XDB_PUBLIC(xdb_header_t *) xdb_load_header(FILE *handle) {
     xdb_header_t *header;
     unsigned int size = xdb_header_info_length;
@@ -57,11 +133,15 @@ XDB_PUBLIC(xdb_header_t *) xdb_load_header(FILE *handle) {
 
     // fill the fields
     header->length = size;
-    header->version = (unsigned short) xdb_get_ushort(header->buffer, 0);
-    header->index_policy = (unsigned short) xdb_get_ushort(header->buffer, 2);
-    header->created_at = xdb_get_uint(header->buffer, 4);
-    header->start_index_ptr = xdb_get_uint(header->buffer, 8);
-    header->end_index_ptr = xdb_get_uint(header->buffer,12);
+    header->version = (unsigned short) xdb_le_get_uint16(header->buffer, 0);
+    header->index_policy = (unsigned short) xdb_le_get_uint16(header->buffer, 2);
+    header->created_at = xdb_le_get_uint32(header->buffer, 4);
+    header->start_index_ptr = xdb_le_get_uint32(header->buffer, 8);
+    header->end_index_ptr = xdb_le_get_uint32(header->buffer,12);
+
+    // since IPv6 supporting
+    header->ip_version = xdb_le_get_uint16(header->buffer, 16);
+    header->runtime_ptr_bytes = xdb_le_get_uint16(header->buffer, 18);
 
     return header;
 }
@@ -194,71 +274,3 @@ XDB_PUBLIC(void) xdb_free_content(void *ptr) {
 }
 
 // --- End
-
-// get unsigned long (4bytes) from a specified buffer start from the specified offset
-XDB_PUBLIC(unsigned int) xdb_get_uint(const char *buffer, int offset) {
-    return (
-        ((buffer[offset  ]) & 0x000000FF) |
-        ((buffer[offset+1] <<  8) & 0x0000FF00) |
-        ((buffer[offset+2] << 16) & 0x00FF0000) |
-        ((buffer[offset+3] << 24) & 0xFF000000)
-    );
-}
-
-// get unsigned short (2bytes) from a specified buffer start from the specified offset
-XDB_PUBLIC(int) xdb_get_ushort(const char *buffer, int offset) {
-    return (
-        ((buffer[offset  ]) & 0x000000FF) |
-        ((buffer[offset+1] << 8) & 0x0000FF00)
-    );
-}
-
-// string ip to unsigned int
-static int shiftIndex[4] = {24, 16, 8, 0};
-XDB_PUBLIC(int) xdb_check_ip(const char *src_ip, unsigned int *dst_ip) {
-    char c;
-    int i, n, ip = 0;
-    const char *ptr = src_ip;
-    for (i = 0; i < 4; i++) {
-        n = 0;
-        while (1) {
-            c = *ptr;
-            ptr++;
-            if (c >= '0' && c <= '9') {
-                n *= 10;
-                n += c - '0';
-            } else if ((i < 3 && c == '.') || i == 3) {
-                // stopping at the '.' but ignore the tailing chars
-                // after the 3rd one (auto clean the tailing none-integer ?).
-                break;
-            } else {
-                return 1;
-            }
-        }
-
-        if (n > 0xFF) {
-            return 2;
-        }
-
-        ip |= (n << shiftIndex[i]);
-    }
-
-    *dst_ip = ip;
-    return 0;
-}
-
-// unsigned int ip to string ip
-XDB_PUBLIC(void) xdb_long2ip(unsigned int ip, char *buffer) {
-    sprintf(buffer, "%d.%d.%d.%d", (ip >> 24) & 0xFF, (ip >> 16) & 0xFF, (ip >> 8) & 0xFF, ip & 0xFF);
-}
-
-// get the middle ip of a and b
-XDB_PUBLIC(unsigned int) xdb_mip(unsigned long a, unsigned long b) {
-    return (unsigned int) ((a + b) >> 1);
-}
-
-XDB_PUBLIC(long) xdb_now() {
-    struct timeval c_time;
-    gettimeofday(&c_time, NULL);
-    return c_time.tv_sec * (int)1e6 + c_time.tv_usec;
-}