关于extern和int main()的结构问题
本帖最后由 hashcat 于 2015-09-20 12:34:50 编辑
这是c实现md5加密的代码，报错部分是两处extern，其实也就是两处extern需要改动，但是试了半天，没搞懂要怎么改...
#include
#include
#define MD5_ROTL(a,b) (MD5_tmp=(a),((MD5_tmp>>(32-b))&(0x7fffffff>>(31-b)))|(MD5_tmp<
#define MD5_F(X,Y,Z) ((X&Y)|((~X)&Z))
#define MD5_G(X,Y,Z) ((X&Z)|(Y&(~Z)))
#define MD5_H(X,Y,Z) (X^Y^Z)
#define MD5_I(X,Y,Z) (Y^(X|(~Z)))
#define MD5_FF(a,b,c,d,Mj,s,ti) a=b+MD5_ROTL((a+MD5_F(b,c,d)+Mj+ti),s)
#define MD5_GG(a,b,c,d,Mj,s,ti) a=b+MD5_ROTL((a+MD5_G(b,c,d)+Mj+ti),s)
#define MD5_HH(a,b,c,d,Mj,s,ti) a=b+MD5_ROTL((a+MD5_H(b,c,d)+Mj+ti),s)
#define MD5_II(a,b,c,d,Mj,s,ti) a=b+MD5_ROTL((a+MD5_I(b,c,d)+Mj+ti),s)
#define MD5main \
{MD5_FF(a, b, c, d, M[0], 7, 0xd76aa478);\
MD5_FF(d, a, b, c, M[1], 12, 0xe8c7b756);\
MD5_FF(c, d, a, b, M[2], 17, 0x242070db);\
MD5_FF(b, c, d, a, M[3], 22, 0xc1bdceee);\
MD5_FF(a, b, c, d, M[4], 7, 0xf57c0faf);\
MD5_FF(d, a, b, c, M[5], 12, 0x4787c62a);\
MD5_FF(c, d, a, b, M[6], 17, 0xa8304613);\
MD5_FF(b, c, d, a, M[7], 22, 0xfd469501);\
MD5_FF(a, b, c, d, M[8], 7, 0x698098d8);\
MD5_FF(d, a, b, c, M[9], 12, 0x8b44f7af);\
MD5_FF(c, d, a, b, M[10], 17, 0xffff5bb1);\
MD5_FF(b, c, d, a, M[11], 22, 0x895cd7be);\
MD5_FF(a, b, c, d, M[12], 7, 0x6b901122);\
MD5_FF(d, a, b, c, M[13], 12, 0xfd987193);\
MD5_FF(c, d, a, b, M[14], 17, 0xa679438e);\
MD5_FF(b, c, d, a, M[15], 22, 0x49b40821);\
MD5_GG(a, b, c, d, M[1], 5, 0xf61e2562);\
MD5_GG(d, a, b, c, M[6], 9, 0xc040b340);\
MD5_GG(c, d, a, b, M[11], 14, 0x265e5a51);\
MD5_GG(b, c, d, a, M[0], 20, 0xe9b6c7aa);\
MD5_GG(a, b, c, d, M[5], 5, 0xd62f105d);\
MD5_GG(d, a, b, c, M[10], 9, 0x02441453);\
MD5_GG(c, d, a, b, M[15], 14, 0xd8a1e681);\
MD5_GG(b, c, d, a, M[4], 20, 0xe7d3fbc8);\
MD5_GG(a, b, c, d, M[9], 5, 0x21e1cde6);\
MD5_GG(d, a, b, c, M[14], 9, 0xc33707d6);\
MD5_GG(c, d, a, b, M[3], 14, 0xf4d50d87);\
MD5_GG(b, c, d, a, M[8], 20, 0x455a14ed);\
MD5_GG(a, b, c, d, M[13], 5, 0xa9e3e905);\
MD5_GG(d, a, b, c, M[2], 9, 0xfcefa3f8);\
MD5_GG(c, d, a, b, M[7], 14, 0x676f02d9);\
MD5_GG(b, c, d, a, M[12], 20, 0x8d2a4c8a);\
MD5_HH(a, b, c, d, M[5], 4, 0xfffa3942);\
MD5_HH(d, a, b, c, M[8], 11, 0x8771f681);\
MD5_HH(c, d, a, b, M[11], 16, 0x6d9d6122);\
MD5_HH(b, c, d, a, M[14], 23, 0xfde5380c);\
MD5_HH(a, b, c, d, M[1], 4, 0xa4beea44);\
MD5_HH(d, a, b, c, M[4], 11, 0x4bdecfa9);\
MD5_HH(c, d, a, b, M[7], 16, 0xf6bb4b60);\
MD5_HH(b, c, d, a, M[10], 23, 0xbebfbc70);\
MD5_HH(a, b, c, d, M[13], 4, 0x289b7ec6);\
MD5_HH(d, a, b, c, M[0], 11, 0xeaa127fa);\
MD5_HH(c, d, a, b, M[3], 16, 0xd4ef3085);\
MD5_HH(b, c, d, a, M[6], 23, 0x04881d05);\
MD5_HH(a, b, c, d, M[9], 4, 0xd9d4d039);\
MD5_HH(d, a, b, c, M[12], 11, 0xe6db99e5);\
MD5_HH(c, d, a, b, M[15], 16, 0x1fa27cf8);\
MD5_HH(b, c, d, a, M[2], 23, 0xc4ac5665);\
MD5_II(a, b, c, d, M[0], 6, 0xf4292244);\
MD5_II(d, a, b, c, M[7], 10, 0x432aff97);\
MD5_II(c, d, a, b, M[14], 15, 0xab9423a7);\
MD5_II(b, c, d, a, M[5], 21, 0xfc93a039);\
MD5_II(a, b, c, d, M[12], 6, 0x655b59c3);\
MD5_II(d, a, b, c, M[3], 10, 0x8f0ccc92);\
MD5_II(c, d, a, b, M[10], 15, 0xffeff47d);\
MD5_II(b, c, d, a, M[1], 21, 0x85845dd1);\
MD5_II(a, b, c, d, M[8], 6, 0x6fa87e4f);\
MD5_II(d, a, b, c, M[15], 10, 0xfe2ce6e0);\
MD5_II(c, d, a, b, M[6], 15, 0xa3014314);\
MD5_II(b, c, d, a, M[13], 21, 0x4e0811a1);\
MD5_II(a, b, c, d, M[4], 6, 0xf7537e82);\
MD5_II(d, a, b, c, M[11], 10, 0xbd3af235);\
MD5_II(c, d, a, b, M[2], 15, 0x2ad7d2bb);\
MD5_II(b, c, d, a, M[9], 21, 0xeb86d391);\
A = a += A, B = b += B, C = c += C, D = d += D;}
int main(){
long MD5_tmp;
extern char* StrMD5(const char* str, long length, char* md5){
/*
计算字符串MD5
参数说明：
str 字符串指针
length 字符串长度
md5 用于保存MD5的字符串指针
返回值为参数md5
*/
char *pp;
long l, i, *M, abcdtmp[4], A, B, C, D, a, b, c, d;
a = A = 0x67452301, b = B = 0xEFCDAB89, c = C = 0x98BADCFE, d = D = 0x10325476;
l = length + ((length % 64 > 56) ? (128 - length % 64) : (64 - length % 64));
if(!(pp = (char*)malloc((unsigned long)l))) return 0;
for (i = 0; i
for (pp[i++] = 128; i
*((long*)(pp + l - 8)) = length <
for (i = 0; i
M = (long*)pp;
MD5main
}
free(pp);
abcdtmp[0] = a, abcdtmp[1] = b, abcdtmp[2] = c, abcdtmp[3] = d;
for (pp = (char*)abcdtmp, i = 0; i
return md5;
}
extern char* FileMD5(const char* file, char* md5){
/*
计算文件MD5
参数说明：
file 文件路径字符串指针
md5 用于保存MD5的字符串指针
返回值为参数md5
*/
FILE* fh;
char* addlp;
long* temp;
long addlsize, j, M[16], abcdtmp[4], A, B, C, D, a, b, c, d;
long long length, i, cpys;
void *pp, *ppend;
fh = fopen(file, "rb");
fseek(fh, 0, SEEK_END);
length = _ftelli64(fh);
a = A = 0x67452301, b = B = 0xEFCDAB89, c = C = 0x98BADCFE, d = D = 0x10325476;
addlsize = (56 - length % 64 > 0) ? (64) : (128);
if (!(addlp = (char*)malloc(addlsize))) return 0;
cpys = ((length - (56 - length % 64)) > 0) ? (length - length % 64) : (0);
j = (long)(length - cpys);
fseek(fh, -j, SEEK_END);
fread(addlp, 1, j, fh);
for (addlp[j++] = 128; j
pp = addlp + addlsize - 8;
*((long long *)pp) = length <
for (rewind(fh); 16 == fread(M, 4, 16, fh);)
MD5main
for (temp = addlp, ppend = addlp + addlsize; temp
for (i = 0; i
MD5main
}
free(addlp);fclose(fh);
abcdtmp[0] = a, abcdtmp[1] = b, abcdtmp[2] = c, abcdtmp[3] = d;
for (addlp = (char*)abcdtmp, i = 0; i
return md5;
}
}
下面是报错。
\Untitled1.c|80|error: nested function 'StrMD5' declared 'extern'
\Untitled1.c|109|error: nested function 'FileMD5' declared 'extern'
------解决思路----------------------
去掉extern声明试试
)
