How to convert the X509 structure into String?

Question

I have pointer to the X509 struct, and I want to convert it to the string, how can i do it? I need to get string like it printed in `PEM_write_X509` function. ``` -----BEGIN CERTIFICATE----- MIIIxjCCB66gAwIBAgIKah4k3wAAAAC/WTANBgkqhkiG9w0BAQUFADBbMRIwEAYK CZImiZPyLGQBGRYCcnUxFjAUBgoJkiaJk/IsZAEZFgZ5YW5kZXgxEjAQBgoJkiaJ k/IsZAEZFgJsZDEZMBcGA1UEAxMQWWFuZGV4RXh0ZXJuYWxDQTAeFw0xMjA5MDQx NDEzMDhaFw0xNDAxMTcxNTE1NDZaMIGQMQswCQYDVQQGEwJSVTEPMA0GA1UECBMG UnVzc2lhMQ8wDQYDVQQHEwZNb3Njb3cxDzANBgNVBAoTBllhbmRleDEMMAoGA1UE CxMDSVRPMRQwEgYDVQQDEwtZYW5kZXggU2VycDEqMCgGCSqGSIb3DQEJARYbc2Vh cmNoLWFkbWluQHlhbmRleC10ZWFtLnJ1MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCB iQKBgQDBXfluaCox4R4D2Y/3mc6O9i3koHtGtHZmZjYm7XdsAA5xsOZAonLReJCL J8BtgS6McmX9cGa9GF9ErxfWODC+1Wb3yayUNzOhr2ICu3T++ttf0aMVvMTeDF/Y lfoZ+tgg1ITQ9yVtz7eteodjLNAy6AaC0z7ulSq4jvPbm1WuBQIDAQABo4IF2DCC BdQwDAYDVR0TAQH/BAIwADALBgNVHQ8EBAMCBaAwggRbBgNVHREEggRSMIIEToIJ eWFuZGV4LmJ5ggp5YW5kZXguY29tgg15YW5kZXguY29tLnRygg15YW5kZXguY29t LnVhggl5YW5kZXgua3qCC3lhbmRl…

Accepted Answer

Use the following function to write in PEM format:

```
int PEM_write_bio_X509(BIO *bp, X509 *x);
```

Then you can read into a char* array with the following function:

```
int    BIO_read(BIO *b, void *buf, int len);
```

Just cast the `void*` to `char*`. Or just use this one, but it will be the same in the end:

```
int    BIO_gets(BIO *b,char *buf, int size);
```

if you pass -1 for `len`, the buffer is assumed to be null terminated.

If you need to find the length, you can do this:

```
BIO *b64;
PEM_write_bio_X509(b64, yourX509);
BUF_MEM *bptr;
BIO_get_mem_ptr(b64, &bptr);
int length = bptr->length;
```

How to convert the X509 structure into String?

Solution

Problem