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Simple base64 decode not working :(

开发者 https://www.devze.com 2023-02-26 15:46 出处:网络
I have been trying to base64 decode the input char * using the following code. The value of \"msg\" seems to be a null string :(

I have been trying to base64 decode the input char * using the following code. The value of "msg" seems to be a null string :(

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <openssl/bn.h>
#include <openssl/bio.h>
#include <openssl/objects.h>
#include <openssl/pem.h>
#include <openssl/objects.h>

// reads b64 encoded msg (pReadBuffer) and writes to pWriiteFile.
char *  dgstdecode(char *pReadBuffer, int pLength)
{
     char *msg = (char *)malloc(pLength);
    memset(ms开发者_如何学编程g, 0x00, pLength);
    int readbytes = -1;

    printf("inside dgstdecode\n");
    printf("\n pReadBuffer = %s \n", pReadBuffer);
    BIO *b64, *bio = NULL;
    b64 = BIO_new(BIO_f_base64());
    bio = BIO_new_mem_buf(pReadBuffer, pLength);
    bio = BIO_push(b64, bio);
   //BIO_set_flags(bio,BIO_FLAGS_BASE64_NO_NL);

    while ((readbytes = BIO_read(bio, msg, pLength)) > 0)
    {
    printf("readbytes:  %d\n", readbytes);
    printf("inside dgstdecode\n");
    }
    BIO_flush(bio);
    printf("msg = %s\n", msg);
    BIO_free_all(bio);
    //BIO_free_all(b64);
    return msg;

}


int main(int argc, char *argv[])
{
    int i = 0;
    char buff [9] ="aGVsbG8K" ;
    //memset(buff, 0, 9);
    char* ptr ;
    ptr = (char*)malloc(9);

    for(i =0;i < 4; i++){

        buff[9] = '\0';

        printf("strlen buff = %d\n", strlen(buff));
        ptr = dgstdecode(buff, 9);
        printf("ptr = %s\n", ptr);
    }

    return 0;

}


Sorry pimmling! Here's the correct approach. I just cleaned up the main function:

int main(int argc, char *argv[])
{
    int i = 0;
    char buff [] ="aGVsbG8K\n\0" ;
    char* ptr ;

    for(i =0;i < 4; i++){

        printf("strlen buff = %d\n", strlen(buff));
        ptr = dgstdecode(buff, strlen(buff));
        printf("ptr = %s\n", ptr);
        printf("\n");
    }

    return 0;
}

My output is now (still doing that dropping the /n thing):

strlen buff = 9 inside dgstdecode

pReadBuffer = aGVsbG8K

readbytes: 6 inside dgstdecode msg = hello

ptr = hello

strlen buff = 9 inside dgstdecode

pReadBuffer = aGVsbG8K

readbytes: 6 inside dgstdecode msg = hello

ptr = hello

strlen buff = 9 inside dgstdecode

pReadBuffer = aGVsbG8K

readbytes: 6 inside dgstdecode msg = hello

ptr = hello

strlen buff = 9 inside dgstdecode

pReadBuffer = aGVsbG8K

readbytes: 6 inside dgstdecode msg = hello

ptr = hello

Disregard my original response below:

The bio = BIO_push(b64, bio); line seems to be the culprit. It seems to be overwriting the reference. Here's my output once I commented that line out (editor seems to be dropping some /n's):

strlen buff = 8
inside dgstdecode

 pReadBuffer = aGVsbG8K 
readbytes:  9
inside dgstdecode
msg = aGVsbG8K
ptr = aGVsbG8K

strlen buff = 8
inside dgstdecode

 pReadBuffer = aGVsbG8K 
readbytes:  9
inside dgstdecode
msg = aGVsbG8K
ptr = aGVsbG8K

strlen buff = 8
inside dgstdecode

 pReadBuffer = aGVsbG8K 
readbytes:  9
inside dgstdecode
msg = aGVsbG8K
ptr = aGVsbG8K

strlen buff = 8
inside dgstdecode

 pReadBuffer = aGVsbG8K 
readbytes:  9
inside dgstdecode
msg = aGVsbG8K
ptr = aGVsbG8K
0

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