C++ 多位Trie在C语言中的实现

当我试图使用gcc编译我的C代码时，我得到了错误分段错误：11。代码正在实现ip查找的多位trie算法，如下所示：

有时代码确实会运行，但大多数情况下它最终会出现分段错误问题

#include <stdio.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <math.h>

/* nodes is an array 8 elements. Each element is a pointer to its child node.*/
/* stride has been taken as 3. therefore 2^3 = 8, the elements in a node */
struct Mt_Node{
    struct Mt_Node* nodes[8];
    int verdict;
};

typedef struct Mt_Node node;

/* Initialize the multibit trie node */
Mt_Node* init_mtnode(){
    node *ret;
        int size;
        ret = static_cast<node *>(malloc(sizeof(node)));
        if (ret == NULL) /* check for NULL */
            return NULL;
        size = 2 << 3;
        if (size >= 8)
            size = 7; /* maximum possible value */
        for (int i = 0 ; i < size ; ++i)
               ret->nodes[i] = NULL;
        ret->verdict = -1;
        return ret;
}

/* Clean up Multibit Trie */
void free_mt(struct Mt_Node *root){
    for( int i=0; i<8; i++){
        if(root->nodes[i]){
        free_mt(root->nodes[i]);
    }

    }
    free(root);
}

/* Insert a Rule */
void insert_rule(struct Mt_Node *root, uint32_t prefix, int prelen, int portnum){

    static int n_rules = 0;
    n_rules ++;

    /* default rule: if packet matches none of the rules, 
     * it will match this default rule, i.e. 0.0.0.0/0 */
    if( prelen == 0 ){
        root->verdict = portnum;
        return;
    }    

    uint32_t    temp_prefix = prefix;
    int curr_bits, curr_bits1;
    Mt_Node     *curr_node = root;

    if(prelen % 3 == 0){
        /* if the condition is 0, then this node will be used, 
        otherwise we will have to move to next node */

        for(int j=0; j<(prelen/3); j++){
            curr_bits = temp_prefix & 0xE0000000;
            temp_prefix = curr_bits >> 29;
            int index = (int) temp_prefix;


            if(curr_node->nodes[index] == NULL){
                curr_node->nodes[index] = init_mtnode();
            }

            curr_node = curr_node->nodes[index];
            temp_prefix=temp_prefix<<3;
        }

        curr_node->verdict = portnum;

    }

    else if(prelen % 3 == 1){

        int b = prelen/3;
        int c = 1;
        for (int i=0; i<b; i++){

            curr_bits = temp_prefix & 0xE0000000;
            temp_prefix = curr_bits >> 29;
            int index = (int) temp_prefix;


            if(curr_node->nodes[index] == NULL){
                curr_node->nodes[index] = init_mtnode();
            }

            curr_node = curr_node->nodes[index];
            temp_prefix=temp_prefix<<3;

        }

        curr_bits = (temp_prefix & 0x80000000)? 1 : 0;
        if(curr_bits == 0){
            for(int z=0; z<4;z++){
                if(curr_node->nodes[z] == NULL){
                curr_node->nodes[z] = init_mtnode();
                (curr_node->nodes[z])->verdict = portnum;
                }
            }
        }

        else {

            for(int z=4; z<8;z++){
                if(curr_node->nodes[z] == NULL){
                curr_node->nodes[z] = init_mtnode();
                (curr_node->nodes[z])->verdict = portnum;
                }
            }
        }

    }

    else if(prelen % 3 == 2){

        int b = prelen/3;
        int c = 0;
        for (int i=0; i<b; i++){

            curr_bits = temp_prefix & 0xE0000000;
            temp_prefix = curr_bits >> 29;
            int index = (int) temp_prefix;


            if(curr_node->nodes[index] == NULL){
                curr_node->nodes[index] = init_mtnode();
            }

            curr_node = curr_node->nodes[index];
            temp_prefix=temp_prefix<<3;

        }

        curr_bits = temp_prefix & 0xc0000000;
        curr_bits = curr_bits>>30;
        int curr_bits1 = (int) curr_bits;

        if(curr_bits1 == 0){
            for(int z=0; z<2;z++){
                if(curr_node->nodes[z] == NULL){
                curr_node->nodes[z] = init_mtnode();
                (curr_node->nodes[z])->verdict = portnum;
            }

        }

    }

        else if(curr_bits1 == 1){
            for(int z=2; z<4;z++){
                if(curr_node->nodes[z] == NULL){
                curr_node->nodes[z] = init_mtnode();
                (curr_node->nodes[z])->verdict = portnum;
            }


        }

    }

        else if(curr_bits1 == 2){
            for(int z=4; z<6;z++){
                if(curr_node->nodes[z] == NULL){
                curr_node->nodes[z] = init_mtnode();
                (curr_node->nodes[z])->verdict = portnum;
            }

        }

    }

        else {

            for(int z=6; z<8;z++){
                if(curr_node->nodes[z] == NULL){
                curr_node->nodes[z] = init_mtnode();
                (curr_node->nodes[z])->verdict = portnum;
            }

        }


    }

}

}

int lookup_ip(Mt_Node *root, uint32_t ip)
{
    uint32_t    temp_prefix = ip;
    Mt_Node      *curr_node = root;
    int         curr_verdict = root->verdict;
    int         curr_bit = 0;
    int         curr_3bits = 0;
    int         curr_bits1 = 0;
    int b =0;

    temp_prefix = temp_prefix & 0xE0000000;
    temp_prefix = temp_prefix >> 29;
    int index = (int) temp_prefix;

        if(curr_node->nodes[index] == NULL){
            return curr_verdict;
        }

        while(curr_node->nodes[index] != NULL){

        curr_verdict = (curr_node->verdict == -1) ? curr_verdict : curr_node->verdict;
        curr_node = curr_node->nodes[index];


        b += 3;

        temp_prefix = (ip << b);
        temp_prefix = temp_prefix & 0xE0000000;
        temp_prefix = temp_prefix >> 29;
        index = (int) temp_prefix;

        }


curr_verdict = (curr_node->verdict == -1) ? curr_verdict : curr_node->verdict;
return curr_verdict ;



}

---

节点中的节点数组有8个元素的空间，但在代码中最大可能值为7。因此，节点[7]没有给定值，当您使用free_mt和引用该元素的其他位置释放节点时，节点[7]中将包含随机垃圾。

解决此类问题的正确工具是调试器。在询问堆栈溢出之前，应该逐行检查代码。如需更多帮助，请阅读。至少，你应该编辑你的问题，包括一个例子，它可以复制你的问题，同时也可以在调试器中做一些观察。这是C还是C++问题？选择一个或另一个标签。你应该仔细查看。或者学习如何。