Question

如果您执行以下示例（几乎完全基于官方https://www.openssl.org/docs/man1.0.2/crypto/BIO_s_mem.html#EXAMPLE）：

#include <openssl/bio.h>
#include <openssl/buffer.h>

int main() {
    BIO *mem = BIO_new(BIO_s_mem());
    BIO_puts(mem, "Hello World\n");

    BUF_MEM *bptr;
    BIO_get_mem_ptr(mem, &bptr);
    BIO_set_close(mem, BIO_NOCLOSE); /* So BIO_free() leaves BUF_MEM alone */
    BIO_free(mem);

    printf("%s", bptr->data);

    BUF_MEM_free(bptr);
    return 0;
}

只有可能按预期工作，具体取决于char之后基础内存缓冲区中未实现的\n偶然为\000的可能性可以通过Valgrind报告确认：

==17122== Conditional jump or move depends on uninitialised value(s)
==17122==    at 0x52CCCC0: vfprintf (vfprintf.c:1632)
==17122==    by 0x52D3898: printf (printf.c:33)
==17122==    by 0x4008CC: main (test1.c:13)
==17122==  Uninitialised value was created by a heap allocation
==17122==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==17122==    by 0x4E9CE77: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==17122==    by 0x4F4A4B3: BUF_MEM_grow_clean (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==17122==    by 0x4F4BBDD: mem_write (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==17122==    by 0x4F4AC8E: BIO_puts (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==17122==    by 0x40086E: main (test1.c:6)

无论如何，我发现这是因为BIO_puts没有将空终止字符串写入内存BIO，即使https://www.openssl.org/docs/man1.0.2/crypto/BIO_puts.html说：

BIO_puts（）尝试将空终止的字符串buf写入BIO b。

所以我的问题是用OpenSSL内存BIO编写和读取以null结尾的字符串的正确方法是什么。

此外，以这种方式使用此API无法泄露敏感数据？

注意我正在使用OpenSSL 1.0.2g。

Answer 1

BIO_puts将所有数据写入字符串直到NUL终止符 - 但它不包括NUL终结符本身。而是使用BIO_write（）：

SELECT
posts.id AS post_id,
posts.title AS post_title,
CASE
WHEN EXISTS (
  SELECT *
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  WHERE posts.id = likes.post_id
  AND likes.user_id = 1
) THEN TRUE
  ELSE FALSE END
  AS liked
FROM posts;

或者：

const char *mystr = "Hello World\n";

BIO_write(mem, mystr, strlen(mystr) + 1);

使用OpenSSL内存BIO以正确的方式写入和读取以null结尾的字符串

1 个答案: