[openssl-users] How to respond to TLS heartbeat in openssl

[Jeffrey Walton]

On Fri, Dec 22, 2017 at 1:32 AM, Keshava Krishna Bhat K
<keshavkrishna88 at gmail.com> wrote:
> Ok, I got to know that
>  openssl version -a gives out the flags used while building openssl.
> so the output of this was
>
> OpenSSL 1.0.2g  1 Mar 2016
> built on: reproducible build, date unspecified
> platform: debian-amd64
> options:  bn(64,64) rc4(16x,int) des(idx,cisc,16,int) blowfish(idx)
> compiler: cc -I. -I.. -I../include  -fPIC -DOPENSSL_PIC -DOPENSSL_THREADS
> -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -m64 -DL_ENDIAN -g -O2
> -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time
> -D_FORTIFY_SOURCE=2 -Wl,-Bsymbolic-functions -Wl,-z,relro -Wa,--noexecstack
> -Wall -DMD32_REG_T=int -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT
> -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM
> -DSHA512_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DWHIRLPOOL_ASM
> -DGHASH_ASM -DECP_NISTZ256_ASM
> OPENSSLDIR: "/usr/lib/ssl"
>
> Since the putput above does not have OPENSSL_NO_HEARTBEATS, I assume
> heartbeats are not disabled in the build.
> So I am back to square one :( -> how do I make the server respond to a TLS
> heartbeat request ? Do I have to read the packet and write it back ?

You should also check <openssl/opensslconf.h> for OPENSSL_NO_HEARTBEATS.

$ cd openssl
$ grep -B 1 -A 1 HEART include/openssl/opensslconf.h
#endif
#ifndef OPENSSL_NO_HEARTBEATS
# define OPENSSL_NO_HEARTBEATS
#endif

Jeff