Unresolved external symbol UI_OpenSSL with latest OpenSSL 3.0.0

[Liastre]

I did this

I've built latest Curl master with latest OpenSSL master

I expected the following

Successful build

curl/libcurl version

7.65.2-DEV

operating system

Building under UWP using VS2017

details

I've got following errors:

Curl.lib(openssl.obj) : error LNK2019: unresolved external symbol _UI_OpenSSL referenced in function _ssl_ui_reader

According to this document https://www.openssl.org/news/changelog.txt UI_OpenSSL() were deprecated and disabled, not sure if suggested UI_null() is safe to use with UI_method_get_reader

Usage of UI_OpenSSL() detected here

curl/lib/vtls/openssl.c

Line 578 in 6c2b7d4

return (UI_method_get_reader(UI_OpenSSL()))(ui, uis);

and there

curl/lib/vtls/openssl.c

Line 596 in 6c2b7d4

return (UI_method_get_writer(UI_OpenSSL()))(ui, uis);

[bagder]

I'm puzzled.

This is what their changelog says about UI_OpenSSL(), exactly:

The UI API becomes a permanent and integral part of libcrypto, i.e. not possible to disable entirely. However, it's still possible to disable the console reading UI method, UI_OpenSSL() (use UI_null() as a fallback).

still possible to disable doesn't mean it is disabled. I just built openssl from git master (again) and then subsequently curl against that lib and it worked just fine with no such linker error:

$ ./src/curl -V
curl 7.65.2-DEV (x86_64-pc-linux-gnu) libcurl/7.65.2-DEV OpenSSL/3.0.0 zlib/1.2.11 brotli/1.0.7 c-ares/1.14.0 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) nghttp2/1.40.0-DEV librtmp/2.3

How are you building your openssl when you get that disabled?

[Liastre]

I'm using build steps according the description for windows uwp:

perl Configure VC-WIN32-UWP --prefix="path" --openssldir="path" 
nmake

It might be I missed some flags

[bagder]

I have no idea what VC-WIN32-UWP does for the OpenSSL build but presumably this then disables that function. We need to understand what define you get set for this so that we can have the curl build use the same one and avoid trying to use UI_OpenSSL() when used.

Do you perhaps get OPENSSL_NO_UI_CONSOLE or OPENSSL_NO_UI defined or something?

[gvanem]

I have no idea what VC-WIN32-UWP does for the OpenSSL build
but presumably this then disables that function.

Seems it's disabled for UWP. From OpenSSL's Configurations/50-win-onecore.conf:

    "VC-WIN32-UWP" => {
        inherit_from    => [ "VC-WIN32-ONECORE" ],
        lflags          => add("/APPCONTAINER"),
        defines         => add("WINAPI_FAMILY=WINAPI_FAMILY_APP",
                               "_WIN32_WINNT=0x0A00"),
        dso_scheme      => "",
        disable         => [ 'ui-console', 'stdio', 'async', 'uplink' ],

[Liastre]

Hey @gvanem ah I see now, thanks. I found original pull-request discussion, there no any clue why it's been disabled. I'll try to rebuild openssl with enabled ui-console.

[bagder]

@Liastre maybe something like this?

diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index fa6d0201a..3cdcbfeb9 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -73,11 +73,11 @@
 #if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_OCSP)
 #include <openssl/ocsp.h>
 #endif
 
 #if (OPENSSL_VERSION_NUMBER >= 0x0090700fL) && /* 0.9.7 or later */     \
-  !defined(OPENSSL_NO_ENGINE)
+  !defined(OPENSSL_NO_ENGINE) && !defined(OPENSSL_NO_UI_CONSOLE)
 #define USE_OPENSSL_ENGINE
 #include <openssl/engine.h>
 #endif
 
 #include "warnless.h"

[gvanem]

... there no any clue why it's been disabled.

@Liastre, presumably since there are no <wincon.h> functions in UWP? So UI_OpenSSL() method won't work.

[Liastre]

Yay @bagder, that works! Everything is ok now. By the way I've tried and was unable to build with enabled ui-console, some unsupported win32 code involved.

@gvanem you are right!