C语言 函数指针三（反向调用）

动态库代码

//简单的动态库开发----报文发送
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

//定义加密函数指针类型
typedef int(*PDesEncSocket)(char *, int , char **, int *);
//定义解密函数指针类型
typedef int(*PDesDecSocket)(char *, int , char **, int *);

//定义上下文结构体
typedef struct _SCK_HANDLE{
    //定义报文IP
    char ipaddress[30];
    //定义报文端口
    char port[10];
    //定义报文接受数组
    unsigned char * buf;
    //定义报文长度
    int buflen;
    //定义加密函数指针变量
    PDesEncSocket pe;
    //定义解密函数指针变量
    PDesDecSocket pd;
}SCK_HANDLE;

//初始化上下文
_declspec(dllexport)
int cltSocketInit(void **handle/*out*/){
    int ERRO_MSG = 0;
    if (handle==NULL)
    {
        ERRO_MSG = 1;
        printf("handle==NULL 报文初始化失败 erro msg:%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    //定义上下文指针
    SCK_HANDLE *shandle = NULL;
    //分配内存
    //详述：此处分配内存必须分配堆内存（malloc函数分配），这也正是malloc函数真正的用途所在
    //此处不可以分配栈内存，栈内存会被系统自动回收，但是报文的发送与接受所使用的上下文SCK_HANDLE，必须长时间存在
    //何时回收必须由用户决定，而不能随便的被回收
    //同样使用静态区也不合适，因为无法人为回收内存空间，必须等待电脑关机，综上所述，只能使用malloc函数分配内存
    shandle = (SCK_HANDLE *)malloc(sizeof(SCK_HANDLE));
    //重置内存空间
    memset(shandle, 0, sizeof(SCK_HANDLE));
    strcpy(shandle->ipaddress,"192.168.0.128");
    strcpy(shandle->port, "88");
    *handle = shandle;
    return ERRO_MSG;
}

//注入加密函数指针
_declspec(dllexport)
int InjectionEnc(void *handle/*in*/, PDesEncSocket pein/*in*/){
    int ERRO_MSG = 0;
    if (handle == NULL||pein==NULL)
    {
        ERRO_MSG = 1;
        printf("handle == NULL||pein==NULL 传入参数不可以为空  erro msg:%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    SCK_HANDLE* sh = (SCK_HANDLE*)handle;
    sh->pe = pein;
    return ERRO_MSG;
}

//注入解密函数指针
_declspec(dllexport)
int InjectionDec(void *handle/*in*/, PDesDecSocket pdin/*in*/){
    int ERRO_MSG = 0;
    if (handle == NULL || pdin == NULL)
    {
        ERRO_MSG = 1;
        printf("handle == NULL||pdin==NULL 传入参数不可以为空  erro msg:%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    SCK_HANDLE* sh = (SCK_HANDLE*)handle;
    sh->pd = pdin;
    return ERRO_MSG;
}

//客户端发报文
_declspec(dllexport)
int cltSocketSend(void *handle/*in*/, unsigned char *buf/*in*/, int buflen/*in*/){
    int ERRO_MSG = 0;
    if (handle==NULL)
    {
        ERRO_MSG = 1;
        printf("handle==NULL handle不可以为NULL erro msg :%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    if (buf == NULL)
    {
        ERRO_MSG = 2;
        printf("buf==NULL buf不可以为NULL erro msg :%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    SCK_HANDLE *sh = NULL;
    sh = (SCK_HANDLE *)handle;
    if (sh->pe == NULL)
    {
        ERRO_MSG = 3;
        printf("加密函数指针不可以为NULL erro msg :%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    //不需要为报文开辟内存，因为加密函数会分配内存
    sh->pe(buf, buflen, &sh->buf, &sh->buflen);
    return ERRO_MSG;
}

//客户端发报文方式二
_declspec(dllexport)
int cltSocketSend2(void *handle/*in*/, unsigned char *buf/*in*/, PDesEncSocket pein/*in*/, int buflen/*in*/){
    int ERRO_MSG = 0;
    if (handle == NULL)
    {
        ERRO_MSG = 1;
        printf("handle==NULL handle不可以为NULL erro msg :%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    if (buf == NULL)
    {
        ERRO_MSG = 2;
        printf("buf==NULL buf不可以为NULL erro msg :%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    if (pein == NULL)
    {
        ERRO_MSG = 4;
        printf("pein==NULL 传入参数函数指针不可以为空 erro msg :%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    SCK_HANDLE *sh = NULL;
    sh = (SCK_HANDLE *)handle;
    //不需要为报文开辟内存，因为加密函数会分配内存
    //函数指针加密
    pein(buf, buflen, &sh->buf, &sh->buflen);
    return ERRO_MSG;
}

//客户端收报文
_declspec(dllexport)
int cltSocketRev(void *handle/*in*/, unsigned char **buf/*out*/, int *buflen/*in*/){
    int ERRO_MSG = 0;
    if (handle == NULL || buf == NULL || buflen==NULL)
    {
        ERRO_MSG = 1;
        printf("handle == NULL || buf == NULL || buflen==NULL erro msg:%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    //定义临时上下文变量
    SCK_HANDLE *sh = NULL;
    sh = (SCK_HANDLE *)handle;
    //不需要分配返回报文的内存，这里有解密函数分配
    if (sh->pd==NULL)
    {
        ERRO_MSG = 2;
        printf("解密函数指针为空  erro msg:%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    //解密报文
    sh->pd(sh->buf, sh->buflen, buf, buflen);
    //释放上下文中字符串数组的内存空间（至于具体应用还是看场景）
    if (sh->buf!=NULL)
    {
        //释放内存
        free(sh->buf);
        //消除野指针
        sh->buf = NULL;
    }
    sh->buflen = 0;
    return ERRO_MSG;
}

//客户端收报文方式二
_declspec(dllexport)
int cltSocketRev2(void *handle/*in*/, unsigned char **buf/*out*/, PDesDecSocket pdin/*in*/, int *buflen/*in*/){
    int ERRO_MSG = 0;
    if (handle == NULL || buf == NULL || buflen == NULL)
    {
        ERRO_MSG = 1;
        printf("handle == NULL || buf == NULL || buflen==NULL erro msg:%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    if (pdin==NULL)
    {
        ERRO_MSG = 2;
        printf("pdin == NULL  msg:%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    //定义临时上下文变量
    SCK_HANDLE *sh = NULL;
    sh = (SCK_HANDLE *)handle;
    //不需要分配返回报文的内存，这里有解密函数分配
    //解密报文
    pdin(sh->buf, sh->buflen, buf, buflen);
    //释放上下文中字符串数组的内存空间（至于具体应用还是看场景）
    if (sh->buf != NULL)
    {
        //释放内存
        free(sh->buf);
        //消除野指针
        sh->buf = NULL;
    }
    sh->buflen = 0;
    return ERRO_MSG;
}

//客户端释放资源
_declspec(dllexport)
int cltSocketDestory(void **handle){
    int ERRO_MSG = 0;
    if (handle==NULL)
    {
        ERRO_MSG = 1;
        printf("handle==NULL%d
", ERRO_MSG);
        return ERRO_MSG;
    }
    if (*handle!=NULL)
    {
        //释放内存
        free(*handle);
        //消除野指针
        *handle = NULL;
    }
    return ERRO_MSG;
}

业务函数代码

#ifndef _NZHANG
#define _NZHANG
//定义加密函数指针类型
typedef int(*PDesEncSocket)(char *, int, char **, int *);
//定义解密函数指针类型
typedef int(*PDesDecSocket)(char *, int, char **, int *);
//初始化上下文
int cltSocketInit(void **handle/*out*/);
//注入加密函数指针
int InjectionEnc(void *handle/*in*/, PDesEncSocket pein/*in*/);
//注入解密函数指针
int InjectionDec(void *handle/*in*/, PDesDecSocket pdin/*in*/);
//客户端发报文
int cltSocketSend(void *handle/*in*/, unsigned char *buf/*in*/, int buflen/*in*/);
//客户端发报文方式二
int cltSocketSend2(void *handle/*in*/, unsigned char *buf/*in*/, PDesEncSocket pein/*in*/, int buflen/*in*/);
//客户端收报文
int cltSocketRev(void *handle/*in*/, unsigned char **buf/*out*/, int *buflen/*in*/);
//客户端收报文方式二
int cltSocketRev2(void *handle/*in*/, unsigned char **buf/*out*/, PDesDecSocket pdin/*in*/, int *buflen/*in*/);
//客户端释放资源
int cltSocketDestory(void **handle);

#endif

//函数指针的反向调用--增加加密解密函数
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include"des.h"
#include"L001.h"

/*
利用函数指针指针实现多种加密方法加密报文
*/

//加密函数1
int DesEncSocket(char *plainstr/*in*/, int plainlen, char **cryptstr/*out*/, int *cryptlen){
    int ERRO_MSG = 0;
    if (plainstr == NULL || cryptstr == NULL || cryptlen == NULL)
    {
        ERRO_MSG = 1;
        printf("加密参数列表为空
");
        return ERRO_MSG;
    }
    //des密文比明文长，但是密文最多比明文多8个字节（所以我取10个足够）
    *cryptstr = (char *)malloc((sizeof(char)*plainlen) + 10);
    if (cryptstr == NULL)
    {
        ERRO_MSG = 2;
        printf("加密函数分配输出内存失败！
");
        return ERRO_MSG;
    }
    int ret = DesEnc((unsigned char *)plainstr, plainlen, (unsigned char *)*cryptstr, cryptlen);
    if (ret != 0)
    {
        ERRO_MSG = 3;
        printf("des加密函数执行失败！
");
        return ERRO_MSG;
    }
    return ERRO_MSG;
}
//解密函数1
int DesDecSocket(char *cryptstr/*in*/, int cryptlen, char **plainstr/*out*/, int *plainlen){
    int ERRO_MSG = 0;
    if (plainstr == NULL || cryptstr == NULL || plainlen == NULL)
    {
        ERRO_MSG = 1;
        printf("解密参数列表为空！
");
        return ERRO_MSG;
    }
    //分配内存空间(des密文只可能比明文长)
    *plainstr = (char *)malloc((sizeof(char)*cryptlen));
    if (plainstr == NULL)
    {
        ERRO_MSG = 2;
        printf("分配输出内存失败！
");
        return ERRO_MSG;
    }
    int ret = DesDec((unsigned char *)cryptstr, cryptlen, (unsigned char *)*plainstr, plainlen);
    if (ret != 0)
    {
        ERRO_MSG = 3;
        printf("des解密函数执行失败！
");
        return ERRO_MSG;
    }
    return ERRO_MSG;
}
//加密函数2
int DesEncSocket2(char *plainstr/*in*/, int plainlen, char **cryptstr/*out*/, int *cryptlen){
    int ERRO_MSG = 0;
    if (plainstr == NULL || cryptstr == NULL || cryptlen == NULL)
    {
        ERRO_MSG = 1;
        printf("加密参数列表为空
");
        return ERRO_MSG;
    }
    //des密文比明文长，但是密文最多比明文多8个字节（所以我取10个足够）
    *cryptstr = (char *)malloc((sizeof(char)*plainlen) + 10);
    if (cryptstr == NULL)
    {
        ERRO_MSG = 2;
        printf("加密函数分配输出内存失败！
");
        return ERRO_MSG;
    }
    int ret = DesEnc((unsigned char *)plainstr, plainlen, (unsigned char *)*cryptstr, cryptlen);
    if (ret != 0)
    {
        ERRO_MSG = 3;
        printf("des加密函数执行失败！
");
        return ERRO_MSG;
    }
    return ERRO_MSG;
}
//解密函数2
int DesDecSocket2(char *cryptstr/*in*/, int cryptlen, char **plainstr/*out*/, int *plainlen){
    int ERRO_MSG = 0;
    if (plainstr == NULL || cryptstr == NULL || plainlen == NULL)
    {
        ERRO_MSG = 1;
        printf("解密参数列表为空！
");
        return ERRO_MSG;
    }
    //分配内存空间(des密文只可能比明文长)
    *plainstr = (char *)malloc((sizeof(char)*cryptlen));
    if (plainstr == NULL)
    {
        ERRO_MSG = 2;
        printf("分配输出内存失败！
");
        return ERRO_MSG;
    }
    int ret = DesDec((unsigned char *)cryptstr, cryptlen, (unsigned char *)*plainstr, plainlen);
    if (ret != 0)
    {
        ERRO_MSG = 3;
        printf("des解密函数执行失败！
");
        return ERRO_MSG;
    }
    return ERRO_MSG;
}

void ProtectA(){
    //定义发送报文
    char str1[30] = "1234567";
    //定义报文长度
    int buflen1 = strlen(str1) + 1;
    //定义接受报文变量
    char *buf = NULL;
    int len2 = 0;
    void *handle = NULL;
    int ret = 0;
    //初始化报文
    ret = cltSocketInit(&handle);
    if (ret != 0)
    {
        printf("初始化报文对象失败！
");
    }
    //注入加密函数指针
    ret = InjectionEnc(handle, DesEncSocket);
    if (ret != 0)
    {
        printf("注入加密函数指针失败！
");
    }
    //注入解密函数指针
    ret = InjectionDec(handle, DesDecSocket);
    if (ret != 0)
    {
        printf("注入解密函数指针失败！
");
    }
    //发送报文
    ret = cltSocketSend(handle, str1, buflen1);
    if (ret != 0)
    {
        printf("发送报文失败！
");
    }
    //接收报文
    ret = cltSocketRev(handle, &buf, &len2);
    if (ret != 0)
    {
        printf("接收报文失败！
");
    }

    //释放报文内存
    if (buf != NULL)
    {
        //打印报文
        printf(buf);
        free(buf);
        buf = NULL;
    }
    //释放报文对象
    ret = cltSocketDestory(&handle);
    if (ret != 0)
    {
        printf("释放报文对象失败！
");
    }
}

void ProtectB(){
    //定义发送报文
    char str1[30] = "1234567";
    //定义报文长度
    int buflen1 = strlen(str1) + 1;
    //定义接受报文变量
    char *buf = NULL;
    int len2 = 0;
    void *handle = NULL;
    int ret = 0;
    //初始化报文
    ret = cltSocketInit(&handle);
    if (ret != 0)
    {
        printf("初始化报文对象失败！
");
    }
    //发送报文
    ret = cltSocketSend2(handle, str1, DesEncSocket2, buflen1);
    if (ret != 0)
    {
        printf("发送报文失败！
");
    }
    //接收报文
    ret = cltSocketRev2(handle, &buf, DesDecSocket2, &len2);
    if (ret != 0)
    {
        printf("接收报文失败！
");
    }

    //释放报文内存
    if (buf != NULL)
    {
        //打印报文
        printf(buf);
        free(buf);
        buf = NULL;
    }
    //释放报文对象
    ret = cltSocketDestory(&handle);
    if (ret != 0)
    {
        printf("释放报文对象失败！
");
    }
}

void main(){
    ProtectB();
    system("pause");
}