s_server crashes with "gethostbyname failure" on iOS connect

[bararchy]

Using Ubuntu 14.04 with latest packages
OpenSSL 1.0.1f 6 Jan 2014

When connecting with iPhone and iOS 10, I'm getting this crash on the server side:

openssl s_server -accept 443 -chain -cert cert/example/example.cert -key cert/example/example.key -www -debug -msg -state
Enter pass phrase for cert/example/example.key:
Using default temp DH parameters
ACCEPT
gethostbyname failure
   0 items in the session cache
   0 client connects (SSL_connect())
   0 client renegotiates (SSL_connect())
   0 client connects that finished
   0 server accepts (SSL_accept())
   0 server renegotiates (SSL_accept())
   0 server accepts that finished
   0 session cache hits
   0 session cache misses
   0 session cache timeouts
   0 callback cache hits
   0 cache full overflows (128 allowed)

Tried to upgrade to the libssl and openssl used in Ubuntu 16.04:
OpenSSL 1.0.2g 1 Mar 2016
and got the same error.

Note all other clients, browsers, etc.. works without a problem on the same server.

[richsalz]

compile with debug and give a backtrace. do other clients make it crash? there is not enough information here.

[bararchy]

@richsalz No other client can make it crash, this happen only with the iPhone.
Trying from a few browsers inside the iPhone produces same results, chrome and default browser both make it crash.

I can compile with debug, though, it's the standard deb package , so I'll need to download the sources first.

[mattcaswell]

This doesn't look like a crash to me. It looks like a properly handled error message. That suggests that it's an OS level issue that really causes gethostbyname() to fail in some way. Perhaps a DNS problem?

[bararchy]

@mattcaswell If so (and that's what I initially thought) why wont it fail like that with every client ? why only iOS ?

[richsalz]

Perhaps because that client isn't in DNS? There is not enough information here.

[mattcaswell]

No, idea although I do suspect a local config issue. Perhaps @levitte can give a hint.

[bararchy]

@richsalz Any place where I can find documentation or steps to compile in debug mode ?

[richsalz]

As “config –help” says, add -d to your configure command line.

[dot-asm]

OpenSSL 1.0.1f 6 Jan 2014

Versions earlier than 1.0.2 are vendors' responsibility, i.e. whatever happens you would have to bring it up with vendor. Otherwise key question is why does it call gethostbyname at all? What name? As for compiling debug version, it wouldn't help, as there is no crash. And you can collect information as it is. [Or rather that having debug build wouldn't make it simpler to collect information.] Start under debugger, set break point at gethostnyname and examine passed string with 'x/s $rdi'. Yes, provide even backtrace, i.e. output from 'where' command [it's just that it would be as informative as with debugging build]. Note that you might have to hit the break point several times. I mean don't stop at first, but continue and examine all calls to gethostbyname.

[dot-asm]

Just to clarify. gdb openssl, then on gdb prompt break gethostbyname followed by run s_server -accept 443 .... Connect from iOS, debugger will stop at breakpoint, x/s $rdi, record the string, where, record the backtrace, continue, x/s $rdi, record the string, where, record, continue, etc. You don't need to build debug openssl version.

[bararchy]

@dot-asm Done (Thanks for the steps)

break

Breakpoint 1, gethostbyname (name=0x6a7110 "2-53-37-28.orange.net.il")
    at ../nss/getXXbyYY.c:88
88	../nss/getXXbyYY.c: No such file or directory.
(gdb) x/s $rdi
0x6a7110:	"2-53-37-28.orange.net.il"

Trace

#0  gethostbyname (name=0x6a7110 "2-53-37-28.orange.net.il")
    at ../nss/getXXbyYY.c:88
#1  0x0000000000449ab5 in ?? ()
#2  0x000000000044a033 in ?? ()
#3  0x0000000000438d99 in ?? ()
#4  0x0000000000418ae8 in ?? ()
#5  0x0000000000418836 in ?? ()
#6  0x00002aaaab32cf45 in __libc_start_main (main=0x418340, argc=9, 
    argv=0x7fffffffe678, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7fffffffe668) at libc-start.c:287
#7  0x00000000004188bb in ?? ()

[dot-asm]

Please confirm that it's the only call to gethostbyname before it fails? I.e. after you collect this execute continue at debugger prompt and check that it doesn't hit the breakpoint again...

As for backtrace. Hmm, I was expecting that it would figure those ?? out... Oh! They provide debug information as separate packages, so you'd need to install some additional packages. Search for ones that end with -dbg...

BTW, I can't resolve the hostname mentioned above. Can you?

[bararchy]

• 1 This is the last "continue" after that the programs exits
• 2 Do you know which programs do I need to install with the debug ? (openssl ?, gdb ? or some dns ?)
• 3 I too cannot resolve it, but, it most likely because it's a PTR or something

[levitte]

• 3 I too cannot resolve it, but, it most likely because it's a PTR or something

No, it means it's not in public DNS, at all.

[bararchy]

@levitte Ok, but does that means it should crash ?
Is there a way to just tell it not to reverse-resolve clients ? (if that's where the issue is from)

@dot-asm
Ok, found out: https://wiki.ubuntu.com/Debug%20Symbol%20Packages
I installed debug symbols for openssl, libssl, libc (just in case).
I rerun the test and no more info was shown, I rebooted the server and will update if there is a change.