const char * tls_version_str(u16 ver);
int tls_prf(u16 ver, const u8 *secret, size_t secret_len, const char *label,
const u8 *seed, size_t seed_len, u8 *out, size_t outlen);
const char * tls_version_str(u16 ver);
int tls_prf(u16 ver, const u8 *secret, size_t secret_len, const char *label,
const u8 *seed, size_t seed_len, u8 *out, size_t outlen);