Download document on Android devices returns unknown file

Downloading resources on Android devices returns unknown file in Google Chrome, or internal browser but not in Firefox for Android!

Short version

• Do not rely on self signed certificate for android when downloading resources: android download manager wont work (below Android 4.1.4 SSL was even not supported in download manager)
• Android do not support all kind of SSL Cipher, check the compatibility table below

Long Story

On some Android devices clicking the download link return back an error and show an ‘Unknown file’. The file of an initial size of 790kb get partially and randomly downloaded: sometimes you get 140kb, sometimes 224kb or more.

There is a workaround: if one lets the cursor on the link and clicks ‘Save’ then the saved document is correct and can be opened.

This issue appear on some Android phone, not on Android tablet (???) and never on iOS (sic)

Looking  at the logs, we have found that In Apache access log the resource-size returned is not the same as in Tomcat access log (only when client is Android). Using Desktop class browser (Google Chrome, Firefox, Opera, Safari) the sizes returned by Tomcat and Apache is the same!

After  a lot of try and error we found out that Android is able to download properly the resource when connecting directly to tomcat (e.g. without SSL), however in this case there is a VERY strange behaviour:

So, when we try to download the resource via HTTP, android needs to connect twice! The first connection seems to abort and only the second connection (Android download manager) is able to fetch everything. 

After that, we enabled the debug logging in Apache and had look at the output.

[Tue Jan 26 16:06:29 2016] [info] Initial (No.1) HTTPS request received for child 0 (server skye3.innoveo.com:443) [Tue Jan 26 16:06:29 2016] [debug] mod_proxy_http.c(56): proxy: HTTP: canonicalising URL //localhost:8443/xx.pdf [Tue Jan 26 16:06:29 2016] [debug] proxy_util.c(1525): [client 172.16.2.176] proxy: http: found worker http://localhost:8443/ for http://localhost:8443/xx.pdf
[Tue Jan 26 16:06:29 2016] [debug] mod_proxy.c(1026): Running scheme http handler (attempt 0) [Tue Jan 26 16:06:29 2016] [debug] mod_proxy_http.c(1982): proxy: HTTP: serving URL http://localhost:8443/xx.pdf [Tue Jan 26 16:06:29 2016] [debug] proxy_util.c(2102): proxy: HTTP: has acquired connection for (localhost) [Tue Jan 26 16:06:29 2016] [debug] proxy_util.c(2158): proxy: connecting http://localhost:8443/xx.pdf to localhost:8443 [Tue Jan 26 16:06:29 2016] [debug] proxy_util.c(2285): proxy: connected /xxxxx.pdf to localhost:8443 [Tue Jan 26 16:06:29 2016] [debug] mod_proxy_http.c(1741): proxy: start body send [Tue Jan 26 16:06:29 2016] [info] [client 172.16.2.176] (104)Connection reset by peer: core_output_filter: writing data to the network [Tue Jan 26 16:06:29 2016] [info] [client 172.16.2.176] (103)Software caused connection abort: SSL output filter write failed. [Tue Jan 26 16:06:29 2016] [debug] mod_proxy_http.c(1851): proxy: end body send [Tue Jan 26 16:06:29 2016] [debug] proxy_util.c(2120): proxy: HTTP: has released connection for (localhost) [Tue Jan 26 16:06:29 2016] [info] [client 172.16.2.176] Connection to child 3 established (server skye3.innoveo.com:443) ... ~removed useless debug output~ [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1966): [client 172.16.2.176] SSL virtual host for servername skye3.innoveo.com found [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 read client hello A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 write server hello A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 write certificate A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 write key exchange A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 write server done A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 flush data Tue Jan 26 16:06:29 2016] [debug] ssl_engine_io.c(1929): OpenSSL: read 5/5 bytes from BIO#7f1a4c1230d0 [mem: 7f1a4c17a493] (BIO dump follows) ... ~removed useless debug output~ [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 read client key exchange A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_io.c(1929): OpenSSL: read 5/5 bytes from BIO#7f1a4c1230d0 [mem: 7f1a4c17a493] (BIO dump follows) ... ~removed useless debug output~ [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 read finished A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 write session ticket A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 write change cipher spec A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 write finished A [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1853): OpenSSL: Loop: SSLv3 flush data [Tue Jan 26 16:06:29 2016] [debug] ssl_engine_kernel.c(1849): OpenSSL: Handshake: done [Tue Jan 26 16:06:29 2016] [info] Connection: Client IP: 172.16.2.176, Protocol: TLSv1.2, Cipher: ECDHE-RSA-AES256-SHA (256/256 bits) [Tue Jan 26 16:06:29 2016] [info] [client 172.16.2.176] (70014)End of file found: SSL input filter read failed. [Tue Jan 26 16:06:29 2016] [info] [client 172.16.2.176] Connection closed to child 2 with standard shutdown (server skye3.innoveo.com:443) [Tue Jan 26 16:06:29 2016] [info] [client 172.16.2.176] Connection to child 0 established (server skye3.innoveo.com:443) ...

So we see, the intial SSL connect works, we can see the request issued and the proxy request. Body is written and then “connection reset by peer”

After careful search it is pretty sure that we are running into this problem: https://code.google.com/p/chromium/issues/detail?id=440951
Summary: 
when you try to download stuff with chromium it works (even from unsecure sources), this is why the first connect is okay. however chromium interrupts the download to hand it over to android download manager (this is why actually displaying pictures works, despite the fact that they are delivered though the same pipeline, e.g. skye code, tomcat version, apache and ssl). this is also why we see two downloads per click in the log files. Problem is however that android download manager does NOT NEVER EVER download stuff from unsecure sources (e.g. selfsigned certs) and thus the final download fails. this is also true for the default andoid browser, because they also use the android download manager.

Solution: the only solution was be to upgrade to valid SSL  certificates (Verizon, Verisign or any other) instead of self signed. This increase the number of Android device working but unfortunately  some Android devices were still NOT able to download resources with a valid SSL cert…

By using the Android SDK debug console (adb.exe logcat > file.txt) of android, we saw the following:

	Line 7487: D/DownloadManager( 3054): [1] Starting 	Line 7489: W/DownloadManager( 3054): [1] Stop requested with status HTTP_DATA_ERROR: Handshake failed 	Line 7491: D/DownloadManager( 3054): [1] Finished with status WAITING_TO_RETRY

This show again that the initial connect to our server happen correctly but return partial content but is then forwarded to the download manager that try to build another connection that is still fail

Solution: change Apache cipher suite according to the table below.

Android compatibility table

http://developer.android.com/reference/javax/net/ssl/SSLEngine.html

Depending on which version of android you would like to support you’ll  have to find a cipher suite that is supported by iOS, Android while not sacrificing too much security. 

It is always a good idea to validate your SSL settings by using one the these online services (In no particular order). Some even report if you are vulnerable to some common SSL attacks ()

• https://www.ssllabs.com/ssltest/ 
• https://cryptoreport.websecurity.symantec.com/checker/views/certCheck.jsp