/*******************************
编译：
gcc -g -o ssha_check ssha_check.c -lssl

测试：
./ssha_check shanghai 8Mhh1STpS0WOcp15/hd26yZMbE9uRMN0NQcBEQ==
ret: 0
*********************************/
//ssha_check.c:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <openssl/sha.h>
#include <openssl/bio.h>
#include <openssl/buffer.h>
 
#define PASSWD_OK      (0)
#define PASSWD_ERR     (-1)
#define SHA1_BYTES 20
 
char *base64_decode(unsigned char *in, int32_t len)
{
    BIO     *b64, *bmem;
 
    char *buffer = (char *)calloc(1, len);
    if (buffer == NULL) {
        printf("alloc memory fail\n");
        return -1;
    }
 
    b64 = BIO_new(BIO_f_base64());
    bmem = BIO_new_mem_buf(in, len);
    bmem = BIO_push(b64, bmem);
 
    BIO_read(bmem, buffer, len);
 
    BIO_free_all(bmem);
 
    return buffer;
}
 
/*
*   @passwd:    source passwd from user intpu
*   @cred:      ssha passwd
*   return:
*       0:      succ
*      -1:      fail
*/
static int chk_ssha1(const char *passwd, const char *cred)
{
    SHA_CTX SHA1context;
    unsigned char SHA1digest[SHA1_BYTES];
    int32_t rc;
    unsigned char *orig_pass = NULL;
    char *cred_pass = NULL;
 
    /* safety check -- must have some salt */
    if (BASE64_DECODE_LEN(strlen(cred)) <= sizeof(SHA1digest)) {
        return PASSWD_ERR;
    }
 
    /* decode base64 password */
    cred_pass = (unsigned char *)calloc(1, strlen(cred) + 1);
    if(cred_pass == NULL ) return PASSWD_ERR;
 
    memcpy(cred_pass, cred, strlen(cred));
    cred_pass[strlen(cred)] = '\n';
    cred_pass[strlen(cred)+1] = '\0';
 
    orig_pass = base64_decode(cred_pass, strlen(cred_pass));
    rc = strlen(orig_pass);
 
    /* safety check -- must have some salt */
    if (rc <= (int)(sizeof(SHA1digest))) {
        free(cred_pass);
        free(orig_pass);
        return PASSWD_ERR;
    }
 
    /* hash credentials with salt */
    SHA1_Init(&SHA1context);    
    SHA1_Update(&SHA1context,
        (const unsigned char *) passwd, strlen(passwd));
    SHA1_Update(&SHA1context,
        (const unsigned char *) &orig_pass[sizeof(SHA1digest)],
        rc - sizeof(SHA1digest));
    SHA1_Final(SHA1digest, &SHA1context);
 
    /* compare */
    rc = memcmp((char *)orig_pass, (char *)SHA1digest, sizeof(SHA1digest));
 
    free(cred_pass);
    free(orig_pass);
 
    return rc ? PASSWD_ERR : PASSWD_OK;
}
 
// ./ssha_check shanghai 8Mhh1STpS0WOcp15/hd26yZMbE9uRMN0NQcBEQ==
int main(int argc, char **argv)
{
    char *passwd = argv[1];
    char *cred = argv[2];
 
    int32_t ret = chk_ssha1(passwd, cred);
 
    printf("ret: %d\n", ret);
 
    return 0;
}