QSslSocket HostNotFoundError QT 5.13

Tomaz · wrote on 13 Jul 2020, 21:46

Well, I use linuxdeployqt app to change the path to needed dynamical linked files or dependency .so files to my lib folder. Thats all. And it works. Second I use patchelf app to change the loader for my app. So I copy my loader from mint 19.2 because at compile time my app links to newer loader that comes with mint 19.2. I am compiling on machine with mint 19.2 installed- I just copy the loader beside my app and change the elf loader (found in /lib/x86_64-linux-gnu/) with patchelf to use my loader from mint 19.2. ld or loader manuall page states that the loader is a portable file and it is encouraging to move the loader beside the elf or app file! My app runs with no problems on mint 17.3 with loader from mint 19.2. Thats it. Now I am asking myself if there is a problem with different glibc files (standard C library - mallock, alock,..etc). Perhaps (after almost every linux app links against glibc) there could be a problem with functions in glibc that differ from mint 17.3 to mint 19.2 when the qabstractsocket/QSslSocket is used/methods called? Does this class uses functions from glibc when the hostlookup is done?

SGaist · wrote on 14 Jul 2020, 19:17

Is OpenSSL also included along your deployed app ?

Tomaz · wrote on 14 Jul 2020, 20:20

In previus answer I forgot to write that deployed glibc.so.6 in lib folder shows dependency to local ld or loader on deployed machine that differs from loader on my development machine. I did change that but it didnt help. Yes... I am suspecting also OpenSSL. But I do not know wich files or .so I have to put beside my elf/app file. Installed version on deployed machine is the same as the method QSslSocket::sslLibraryBuildVersionString() is showing or Qt is compiling against- 1.1.1b OpenSsl version. Could it be that my executable is looking for .so or OpenSsl files in some Qt folder on deployed machine? And those folders and files do not exists?

SGaist · wrote on 15 Jul 2020, 20:20

Did you check with ldd if everything can load ?

Tomaz · wrote on 15 Jul 2020, 20:51

Hi. First, thanks for helping me out! Yes ldd shows everything is loading. Output of ldd is:

tomaz@tomaz-HP-350-G1:~/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release$ ldd mail
linux-vdso.so.1 (0x00007fff70180000)
libQt5Widgets.so.5 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libQt5Widgets.so.5 (0x00007fc18794f000)
libQt5Network.so.5 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libQt5Network.so.5 (0x00007fc18759f000)
libQt5Core.so.5 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libQt5Core.so.5 (0x00007fc186df2000)
libstdc++.so.6 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libstdc++.so.6 (0x00007fc186a27000)
libgcc_s.so.1 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libgcc_s.so.1 (0x00007fc18680e000)
libc.so.6 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libc.so.6 (0x00007fc186416000)
libQt5Gui.so.5 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libQt5Gui.so.5 (0x00007fc185bc9000)
libpthread.so.0 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libpthread.so.0 (0x00007fc1859a8000)
libGL.so.1 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libGL.so.1 (0x00007fc18570a000)
libm.so.6 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libm.so.6 (0x00007fc185369000)
libz.so.1 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libz.so.1 (0x00007fc18514b000)
libdl.so.2 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libdl.so.2 (0x00007fc184f46000)
libicui18n.so.56 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libicui18n.so.56 (0x00007fc184aad000)
libicuuc.so.56 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libicuuc.so.56 (0x00007fc1846f5000)
libicudata.so.56 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libicudata.so.56 (0x00007fc182d12000)
libgthread-2.0.so.0 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libgthread-2.0.so.0 (0x00007fc182b0f000)
libglib-2.0.so.0 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libglib-2.0.so.0 (0x00007fc1827ee000)
ld-2.27.so => /lib64/ld-linux-x86-64.so.2 (0x00007fc1883b0000)
libGLX.so.0 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libGLX.so.0 (0x00007fc1825bc000)
libGLdispatch.so.0 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libGLdispatch.so.0 (0x00007fc182305000)
libpcre.so.3 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libpcre.so.3 (0x00007fc182092000)
libX11.so.6 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libX11.so.6 (0x00007fc181d54000)
libxcb.so.1 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libxcb.so.1 (0x00007fc181b27000)
libXau.so.6 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libXau.so.6 (0x00007fc181922000)
libXdmcp.so.6 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libXdmcp.so.6 (0x00007fc18171b000)
libbsd.so.0 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/libbsd.so.0 (0x00007fc181505000)
librt.so.1 => /home/tomaz/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release/./lib/librt.so.1 (0x00007fc1812fc000)
tomaz@tomaz-HP-350-G1:~/QtProjekti/build-mail-Desktop_Qt_5_13_0_GCC_64bit-Release$

SGaist · 17 Jul 2020, 20:12

Next I would go with strace, OpenSSL is not linked by default but dlopened so it won't appear using ldd.

Tomaz · S SGaist 16 Jul 2020, 17:54

I tried strace. In did there were some ssl files missing. I copied them to my lib folder after strace showed my app searched for them in lib folder. It didnt helped. Now...after it didnt resolved dns and strace shows that app or sslsocket opens etc/hosts file to resolve domain name I just added ip and domain name of smtp server. And now it works. So my app resolves domain from my hosts file. Strange. I cant understand why it dint resolve smtp name from outer dns server? Do you have any explanation?

SGaist · 18 Jul 2020, 14:23

Nice !

That's a good question that I currently do not have an answer for, sorry. Maybe the folks from the linuxdeployqt project might have an idea.

Tomaz · 18 Jul 2020, 15:19

Huh it turn out that on deployed machine the openssl version must be the same as on developing machine in qts folder. That in my case 1.1.1b. So if deploying machine has diffrent version of openssl istalled you have to move some so.1.1 files like ssl, dns, crypto and some other files into deployed machine lib folder or aside elf/app executable. Strace did help. Thank you.

Pablo J. Rogina · T Tomaz 18 Jul 2020, 14:23

@Tomaz if your issue is solved now, please don't forget to mark your post as such!