ModSecurity/apache2/msc_tree.c

/*
 * ModSecurity for Apache 2.x, http://www.modsecurity.org/
 * Copyright (c) 2004-2013 Trustwave Holdings, Inc. (http://www.trustwave.com/)
 *
 * You may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * If any of the files related to licensing are missing or if you have any
 * other questions related to licensing please contact Trustwave Holdings, Inc.
 * directly using the email address security@modsecurity.org.
 */

#include <stdio.h>
#include <stdlib.h>
#if APR_HAVE_STDINT_H
#include <stdint.h>
#endif
#include <string.h>
#if APR_HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#if APR_HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#include "apr_lib.h"
#include "msc_util.h"
#include "msc_tree.h"

CPTTree *CPTCreateRadixTree(apr_pool_t *pool)   {
    CPTTree *tree = NULL;

    tree = apr_palloc(pool, sizeof(CPTTree));

    if(tree == NULL)
        return NULL;

    memset(tree, 0, sizeof(CPTTree));
    tree->pool = pool;

    return tree;
}

void ConvertIPNetmask(unsigned char *buffer, unsigned char netmask, unsigned int ip_bitmask) {
    int aux = 0, bytes = 0;
    int mask = 0, mask_bit = 0;

    bytes = ip_bitmask/8;

    while(aux < bytes)    {
        mask_bit  = ((1+aux) * 8);

        if (mask_bit > netmask) {
            mask = 0;
            if ((mask_bit - netmask) < 8)   mask = SHIFT_LEFT_MASK(mask_bit - netmask);
        }   else    {
            mask = -1;
        }

        buffer[aux] &= mask;
        aux++;
    }

    return;
}

TreeNode *CPTCreateNode(apr_pool_t *pool)   {
    TreeNode *node = NULL;

    node = apr_palloc(pool, sizeof(TreeNode));

    if(node == NULL)
        return NULL;

    memset(node, 0, sizeof(TreeNode));
    return node;
}

CPTData *CPTCreateCPTData(unsigned char netmask, apr_pool_t *pool) {

    CPTData *prefix_data = apr_palloc(pool, sizeof(CPTData));

    if (prefix_data == NULL) {
        return NULL;
    }

    memset(prefix_data, 0, sizeof(CPTData));

    prefix_data->netmask = netmask;

    return prefix_data;
}

TreePrefix *InsertDataPrefix(TreePrefix *prefix, unsigned char *ipdata, unsigned int ip_bitmask,
        unsigned char netmask, apr_pool_t *pool)  {

    if(prefix == NULL)
        return NULL;

    memcpy(prefix->buffer, ipdata, ip_bitmask/8);
    prefix->bitlen = ip_bitmask;

    prefix->prefix_data = CPTCreateCPTData(netmask, pool);

    if(prefix->prefix_data == NULL)
        return NULL;

    return prefix;
}

TreePrefix *CPTCreatePrefix(unsigned char *ipdata, unsigned int ip_bitmask,
        unsigned char netmask, apr_pool_t *pool)  {

    TreePrefix *prefix = NULL;
    int bytes = ip_bitmask/8;

    if ((ip_bitmask % 8 != 0) || (ipdata == NULL)) {
        return NULL;
    }

    prefix = apr_palloc(pool, sizeof(TreePrefix));
    if (prefix == NULL)
        return NULL;

    memset(prefix, 0, sizeof(TreePrefix));

    prefix->buffer = apr_palloc(pool, bytes);

    if(prefix->buffer == NULL)
        return NULL;

    memset(prefix->buffer, 0, bytes);

    return InsertDataPrefix(prefix, ipdata, ip_bitmask, netmask, pool);
}

void CPTAppendToCPTDataList(CPTData *new, CPTData **list)  {
    CPTData *temp = NULL, *prev = NULL;

    if (new == NULL) {
        return;
    }

    if (list == NULL) {
        return;
    }

    prev = *list;
    temp = *list;

    while (temp != NULL) {
        if (new->netmask > temp->netmask)
            break;
        prev = temp;
        temp = temp->next;
    }

    if (temp == *list) {
        new->next = *list;
        *list = new;
    } else {
        new->next = prev->next;
        prev->next = new;
    }

    return;
}

int TreePrefixContainNetmask(TreePrefix *prefix, unsigned char netmask)   {
    CPTData *prefix_data = NULL;

    if (prefix == NULL) {
        return 0;
    }

    prefix_data = prefix->prefix_data;

    while (prefix_data != NULL) {
        if (prefix_data->netmask == netmask)
            return 1;
        prefix_data = prefix_data->next;
    }

    return 0;
}

int CheckBitmask(unsigned char netmask, unsigned int ip_bitmask)   {

    switch(netmask) {

        case 0xff:
            return 1;
        case 0x20:
            if(ip_bitmask == 0x20)
                return 1;
            break;
        case 0x80:
            if(ip_bitmask == 0x80)
                return 1;
            break;
    }

    return 0;
}

TreeNode *CPTCreateHead(TreePrefix *prefix, TreeNode *node, CPTTree *tree, unsigned char netmask, unsigned int ip_bitmask)    {

    if(tree == NULL)
        return NULL;

    if(prefix == NULL)
        return NULL;

    if (node != NULL)   {

        node->prefix = prefix;
        node->bit = prefix->bitlen;
        tree->head = node;

        if(CheckBitmask(netmask, ip_bitmask))
            return node;

        node->count++;
        node->netmasks = apr_palloc(tree->pool, (node->count *  sizeof(unsigned char)));

        if(node->netmasks)
            node->netmasks[0] = netmask;

        return node;

    } else {
        return NULL;
    }

    return NULL;
}

TreeNode *SetParentNode(TreeNode *node, TreeNode *new_node, CPTTree *tree)  {

    if (node->parent == NULL)
        tree->head = new_node;
    else if (node->parent->right == node)
        node->parent->right = new_node;
    else
        node->parent->left = new_node;

    return new_node;
}

int InsertNetmask(TreeNode *node, TreeNode *parent, TreeNode *new_node,
        CPTTree *tree, unsigned char netmask, unsigned char bitlen) {
    int i;

    if (netmask != NETMASK_256-1 && netmask != NETMASK_128) {
        if ((netmask != NETMASK_32 || (netmask == NETMASK_32 && bitlen != NETMASK_32))) {

            node = new_node;
            parent = new_node->parent;

            while (parent != NULL && netmask < (parent->bit + 1)) {
                node = parent;
                parent = parent->parent;
            }

            node->count++;
            node->netmasks = apr_palloc(tree->pool, (node->count * sizeof(unsigned char)));

            if(node->netmasks == NULL)
                return 0;
            if ((node->count-1) == 0) {
                node->netmasks[0] = netmask;
                return 1;
            }

            node->netmasks[node->count - 1] = netmask;

            i = node->count - 2;
            while (i >= 0) {
                if (netmask < node->netmasks[i]) {
                    node->netmasks[i + 1] = netmask;
                    break;
                }

                node->netmasks[i + 1] = node->netmasks[i];
                node->netmasks[i] = netmask;
                i--;
            }
        }
    }

    return 0;
}

TreeNode *CPTAddElement(unsigned char *ipdata, unsigned int ip_bitmask, CPTTree *tree, unsigned char netmask)   {
    unsigned char *buffer = NULL;
    unsigned char bitlen = 0;
    int bit_validation = 0, test_bit = 0;
    int i = 0, j = 0, temp = 0;
    unsigned int x, y;
    TreeNode *node = NULL, *new_node = NULL;
    TreeNode *parent = NULL, *i_node = NULL;
    TreeNode *bottom_node = NULL;
    TreePrefix *prefix = NULL;

    if (tree == NULL) {
        return NULL;
    }

    ConvertIPNetmask(ipdata, netmask, ip_bitmask);

    prefix = CPTCreatePrefix(ipdata, ip_bitmask, netmask, tree->pool);

    if (prefix == NULL) {
        return NULL;
    }

    if (tree->head == NULL) {
        node = CPTCreateNode(tree->pool);
        return CPTCreateHead(prefix, node, tree, netmask, ip_bitmask);
    }

    node = tree->head;
    buffer = prefix->buffer;
    bitlen = prefix->bitlen;

    while (node->bit < bitlen || node->prefix == NULL) {

        if (bitlen < node->bit) {
            if (node->right == NULL)
                break;
            else
                node = node->right;
        } else {
            x = SHIFT_RIGHT_MASK(node->bit, 3); y = SHIFT_RIGHT_MASK(NETMASK_128, (node->bit % 8));

            if (TREE_CHECK(buffer[x],y)) {
                if (node->right == NULL)
                    break;
                node = node->right;
            } else {
                if (node->left == NULL)
                    break;
                else
                    node = node->left;
            }
        }
    }

    bottom_node = node;

    if(node->bit < bitlen)
        bit_validation = node->bit;
    else
        bit_validation = bitlen;

    for (i = 0; (i * NETMASK_8) < bit_validation; i++) {
        int net = 0, div = 0;
        int cnt = 0;

        if ((temp = (buffer[i] ^ bottom_node->prefix->buffer[i])) == 0) {
            test_bit = (i + 1) * NETMASK_8;
            continue;
        }

        temp += temp;

        for(cnt = 0, net = NETMASK_256, div = 2; net >= NETMASK_2; net = NETMASK_256/div,
                div += div, cnt++)      {
            if(temp >= net)   {
                test_bit = (i * NETMASK_8) + cnt;
                break;
            }
        }
        break;
    }

    if (bit_validation < test_bit)
        test_bit = bit_validation;

    parent = node->parent;

    while (parent && test_bit <= parent->bit) {
        node = parent;
        parent = node->parent;
    }

    if (test_bit == bitlen && node->bit == bitlen) {
        if (node->prefix != NULL) {
            int found = 0;
            CPTData *prefix_data = NULL;

            prefix_data = node->prefix->prefix_data;

            while(prefix_data != NULL)  {
                if (prefix_data->netmask == netmask)
                    ++found;
                prefix_data = prefix_data->next;
            }

            if (found != 0) {

                CPTData *prefix_data = CPTCreateCPTData(netmask, tree->pool);
                CPTAppendToCPTDataList(prefix_data, &prefix->prefix_data);

                if(CheckBitmask(netmask, ip_bitmask))
                    return node;

                parent = node->parent;
                while (parent != NULL && netmask < (parent->bit + 1)) {
                    node = parent;
                    parent = parent->parent;
                }

                node->count++;
                new_node = node;
                node->netmasks = apr_palloc(tree->pool, (node->count *  sizeof(unsigned char)));

                if ((node->count -1) == 0) {
                    node->netmasks[0] = netmask;
                    return new_node;
                }

                node->netmasks[node->count - 1] = netmask;

                i = node->count - 2;
                while (i >= 0) {
                    if (netmask < node->netmasks[i]) {
                        node->netmasks[i + 1] = netmask;
                        break;
                    }

                    node->netmasks[i + 1] = node->netmasks[i];
                    node->netmasks[i] = netmask;
                    i--;
                }
            }
        } else {
            node->prefix = CPTCreatePrefix(prefix->buffer, prefix->bitlen,
                    NETMASK_256-1, tree->pool);
        }
        return node;
    }

    new_node = CPTCreateNode(tree->pool);

    if(new_node == NULL)
        return NULL;

    new_node->prefix = prefix;
    new_node->bit = prefix->bitlen;

    if (test_bit == bitlen) {

        x = SHIFT_RIGHT_MASK(test_bit, 3); y = SHIFT_RIGHT_MASK(NETMASK_128, (test_bit % 8));

        if (TREE_CHECK(bottom_node->prefix->buffer[x],y)) {
            new_node->right = node;
        } else {
            new_node->left = node;
        }

        new_node->parent = node->parent;
        node->parent = SetParentNode(node, new_node, tree);

    } else {
        i_node = CPTCreateNode(tree->pool);

        if(i_node == NULL)
            return NULL;

        //i_node->prefix = NULL;
        i_node->bit = test_bit;
        i_node->parent = node->parent;

        if (node->netmasks != NULL) {
            i = 0;
            while(i < node->count) {
                if (node->netmasks[i] < test_bit + 1)
                    break;
                i++;
            }

            i_node->netmasks = apr_palloc(tree->pool, (node->count - i) * sizeof(unsigned char));

            if(i_node->netmasks == NULL) {
                return NULL;
            }

            j = 0;
            while (j < (node->count - i))   {
                i_node->netmasks[j] = node->netmasks[i + j];
                j++;
            }

            i_node->count = (node->count - i);
            node->count = i;

            if (node->count == 0) {
                node->netmasks = NULL;
            }
        }

        x = SHIFT_RIGHT_MASK(test_bit, 3); y = SHIFT_RIGHT_MASK(NETMASK_128, (test_bit % 8));

        if (TREE_CHECK(buffer[x],y)) {
            i_node->left = node;
            i_node->right = new_node;
        } else {
            i_node->left = new_node;
            i_node->right = node;
        }

        new_node->parent = i_node;
        node->parent = SetParentNode(node, i_node, tree);
    }

    if (InsertNetmask(node, parent, new_node, tree, netmask, bitlen))
        return new_node;

    return new_node;
}

int TreeCheckData(TreePrefix *prefix, CPTData *prefix_data, unsigned int netmask)   {

    while(prefix_data != NULL)  {
        if (prefix_data->netmask == netmask) {
            return 1;
        }
        prefix_data = prefix_data->next;
    }

    return 0;
}

int TreePrefixNetmask(modsec_rec *msr, TreePrefix *prefix, unsigned int netmask, int flag)   {
    CPTData *prefix_data = NULL;
    int ret = 0;

    if (prefix == NULL) {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "TreePrefixNetmask: prefix is NULL.");
        }
        return 0;
    }

    prefix_data = prefix->prefix_data;

    if (flag == 1) {

        if(prefix_data == NULL) return 0;

        if (prefix_data->netmask != netmask) {
            if (msr && msr->txcfg->debuglog_level >= 9) {
                msr_log(msr, 9, "TreePrefixNetmask: Cannot find a prefix with correct netmask.");
            }
            return 0;
        } else {
            if (msr && msr->txcfg->debuglog_level >= 9) {
                msr_log(msr, 9, "TreePrefixNetmask: Found a prefix with correct netmask.");
            }
            return 1;
        }
    }

    if (msr && msr->txcfg->debuglog_level >= 9) {
        msr_log(msr, 9, "TreePrefixNetmask: Check if a prefix has a the correct netmask");
    }

    ret = TreeCheckData(prefix, prefix_data, netmask);

    return ret;
}

TreeNode *CPTRetriveNode(modsec_rec *msr, unsigned char *buffer, unsigned int ip_bitmask, TreeNode *node)  {
    unsigned int x, y;

    if(node == NULL)    {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTRetriveNode: Node tree is NULL.");
        }
        return NULL;
    }

    if(buffer == NULL)  {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTRetriveNode: Empty ip address. Nothing to search for.");
        }
        return NULL;
    }

    while (node->bit < ip_bitmask) {

        x = SHIFT_RIGHT_MASK(node->bit, 3); y = SHIFT_RIGHT_MASK(NETMASK_128, (node->bit % 8));

        if (TREE_CHECK(buffer[x], y)) {
            node = node->right;
            if (node == NULL)   return NULL;
        } else {
            node = node->left;
            if (node == NULL)   return NULL;
        }
    }

    if (msr && msr->txcfg->debuglog_level >= 9) {
        msr_log(msr, 9, "CPTRetriveNode: Found the node for provided ip address.");
    }


    return node;
}

TreeNode *CPTRetriveParentNode(TreeNode *node)  {

    while (node != NULL && node->netmasks == NULL)
        node = node->parent;

    return node;
}

TreeNode *CPTFindElementIPNetblock(modsec_rec *msr, unsigned char *ipdata, unsigned char ip_bitmask, TreeNode *node) {
    TreeNode *netmask_node = NULL;
    int mask = 0,  bytes = 0;
    int i = 0, j = 0;
    int mask_bits = 0;

    node = CPTRetriveParentNode(node);

    if (node == NULL)   {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTFindElementIPNetblock: Node tree is NULL.");
        }
        return NULL;
    }

    netmask_node = node;

    while(j < netmask_node->count)    {
        bytes = ip_bitmask / 8;

        while( i < bytes )  {

            mask = -1;
            mask_bits = ((i + 1) * 8);

            if (mask_bits > netmask_node->netmasks[j]) {
                if ((mask_bits - netmask_node->netmasks[j]) < 8)
                    mask = SHIFT_LEFT_MASK(mask_bits - netmask_node->netmasks[j]);
                else
                    mask = 0;
            }

            ipdata[i] &= mask;
            i++;
        }

        node = CPTRetriveNode(msr, ipdata, ip_bitmask, node);

        if (node && node->bit != ip_bitmask)    {
            if (msr && msr->txcfg->debuglog_level >= 9) {
                msr_log(msr, 9, "CPTFindElementIPNetblock: Found a tree node but netmask is different.");
            }
            return NULL;
        }

        if (node && node->prefix == NULL)   {
            if (msr && msr->txcfg->debuglog_level >= 9) {
                msr_log(msr, 9, "CPTFindElementIPNetblock: Found a tree node but prefix is NULL.");
            }
            return NULL;
        }

        if (memcmp(node->prefix->buffer, ipdata, bytes) == 0) {
            mask = SHIFT_LEFT_MASK(8 - ip_bitmask % 8);

            if ((ip_bitmask % 8) == 0) {
                if (TreePrefixNetmask(msr, node->prefix, netmask_node->netmasks[j], FALSE)) {
                    if (msr && msr->txcfg->debuglog_level >= 9) {
                        msr_log(msr, 9, "CPTFindElementIPNetblock: Node found for provided ip address");
                    }
                    return node;
                }
            }

            if ((node->prefix->buffer[bytes] & mask) == (ipdata[bytes] & mask)) {
                if (TreePrefixNetmask(msr, node->prefix, netmask_node->netmasks[j], FALSE)) {
                    if (msr && msr->txcfg->debuglog_level >= 9) {
                        msr_log(msr, 9, "CPTFindElementIPNetblock: Node found for provided ip address");
                    }
                    return node;
                }
            }
        }

        j++;
    }

    return CPTFindElementIPNetblock(msr, ipdata, ip_bitmask, netmask_node->parent);
}

TreeNode *CPTFindElement(modsec_rec *msr, unsigned char *ipdata, unsigned int ip_bitmask, CPTTree *tree)   {
    TreeNode *node = NULL;
    int mask = 0, bytes = 0;
    unsigned char temp_data[NETMASK_256-1];

    if (tree == NULL)   {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTFindElement: Tree is NULL. Cannot proceed searching the ip.");
        }
        return node;
    }

    if (tree->head == NULL) {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTFindElement: Tree head is NULL. Cannot proceed searching the ip.");
        }
        return node;
    }

    node = tree->head;

    if (ip_bitmask > (NETMASK_256-1))   {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTFindElement: Netmask cannot be greater than 255");
        }
        return NULL;
    }

    bytes = ip_bitmask/8;

    memset(temp_data, 0, NETMASK_256-1);
    memcpy(temp_data, ipdata, bytes);

    node = CPTRetriveNode(msr, temp_data, ip_bitmask, node);

    if (node && (node->bit != ip_bitmask)) {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTFindElement: Found a tree node but netmask is different.");
        }
        return NULL;
    }

    if(node == NULL)    {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTFindElement: Node tree is NULL.");
        }
        return node;
    }

    if(node->prefix == NULL)    {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTFindElement: Found a tree node but prefix is NULL.");
        }
        return node;
    }

    if (memcmp(node->prefix->buffer, temp_data, bytes) == 0) {
        mask = SHIFT_LEFT_MASK(8 - ip_bitmask % 8);

        if ((ip_bitmask % 8) == 0) {
            if (TreePrefixNetmask(msr, node->prefix, ip_bitmask, TRUE)) {
                if (msr && msr->txcfg->debuglog_level >= 9) {
                    msr_log(msr, 9, "CPTFindElement: Node found for provided ip address");
                }
                return node;
            }
        }

        if ((node->prefix->buffer[bytes] & mask) == (temp_data[bytes] & mask)) {
            if (TreePrefixNetmask(msr, node->prefix, ip_bitmask, TRUE)) {
                if (msr && msr->txcfg->debuglog_level >= 9) {
                    msr_log(msr, 9, "CPTFindElement: Node found for provided ip address");
                }
                return node;
            }
        }
    }

    return CPTFindElementIPNetblock(msr, temp_data, ip_bitmask, node);
}

TreeNode *CPTIpMatch(modsec_rec *msr, unsigned char *ipdata, CPTTree *tree, int type)   {

    if(tree == NULL)  {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTIpMatch: Tree is NULL. Cannot proceed searching the ip.");
        }
        return NULL;
    }

    if(ipdata == NULL)  {
        if (msr && msr->txcfg->debuglog_level >= 9) {
            msr_log(msr, 9, "CPTIpMatch: Empty ip address. Nothing to search for.");
        }
        return NULL;
    }

    switch(type)    {
        case IPV4_TREE:
            if (msr && msr->txcfg->debuglog_level >= 9) {
                msr_log(msr, 9, "CPTIpMatch: Searching ip type 0x%x", type);
            }
            return CPTFindElement(msr, ipdata, NETMASK_32, tree);
        case IPV6_TREE:
            if (msr && msr->txcfg->debuglog_level >= 9) {
                msr_log(msr, 9, "CPTIpMatch: Searching ip type 0x%x", type);
            }
            return CPTFindElement(msr, ipdata, NETMASK_128, tree);
        default:
            if (msr && msr->txcfg->debuglog_level >= 9) {
                msr_log(msr, 9, "CPTIpMatch: Unknown ip type 0x%x", type);
            }
            return NULL;
    }
}

TreeNode *TreeAddIP(const char *buffer, CPTTree *tree, int type) {
    unsigned long ip, ret;
    unsigned char netmask_v4 = NETMASK_32, netmask_v6 = NETMASK_128;
    char ip_strv4[NETMASK_32], ip_strv6[NETMASK_128];
    struct in_addr addr4;
    struct in6_addr addr6;
    int pos = 0;
    char *ptr = NULL;

    if(tree == NULL)
        return NULL;

    pos = strchr(buffer, '/') - buffer;

    switch(type)    {

        case IPV4_TREE:
            memset(&addr4, 0, sizeof(addr4));
            memset(ip_strv4, 0x0, NETMASK_32);

            strncpy(ip_strv4, buffer, sizeof(ip_strv4));
            *(ip_strv4 + (sizeof(ip_strv4) - 1)) = '\0';

            ptr = strdup(ip_strv4);
            netmask_v4 = is_netmask_v4(ptr);

            if (netmask_v4 > NETMASK_32) {
                free(ptr);
                ptr = NULL;
                return NULL;
            }

            if(ptr != NULL) {
                free(ptr);
                ptr = NULL;
            }

            if(netmask_v4 == 0) {
                return NULL;
            }
            else if (netmask_v4 != NETMASK_32 && pos < strlen(ip_strv4)) {
                ip_strv4[pos] = '\0';
            }

            ret = inet_pton(AF_INET, ip_strv4, &addr4);

            if (ret <= 0) {
                return NULL;
            }

            ip = addr4.s_addr;

            tree->count++;

            return CPTAddElement((unsigned char *)&ip, NETMASK_32, tree, netmask_v4);

        case IPV6_TREE:
            memset(&addr6, 0, sizeof(addr6));
            memset(ip_strv6, 0x0, NETMASK_128);

            strncpy(ip_strv6, buffer, sizeof(ip_strv6));
            *(ip_strv6 + sizeof(ip_strv6) - 1) = '\0';

            ptr = strdup(ip_strv6);
            netmask_v6 = is_netmask_v6(ptr);

            if (netmask_v6 > NETMASK_128) {
                free(ptr);
                ptr = NULL;
                return NULL;
            }

            if(ptr != NULL) {
                free(ptr);
                ptr = NULL;
            }

            if(netmask_v6 == 0) {
                return NULL;
            }
            else if (netmask_v6 != NETMASK_128 && pos < strlen(ip_strv6)) {
                ip_strv6[pos] = '\0';
            }

            ret = inet_pton(AF_INET6, ip_strv6, &addr6);

            if (ret <= 0)
            {
                return NULL;
            }

            tree->count++;

            return CPTAddElement((unsigned char *)&addr6.s6_addr, NETMASK_128, tree, netmask_v6);
        default:
            return NULL;
    }

    return NULL;
}