Bug#516543: lt-sample-client: Decoding data from base64: bad protocol / cancel

[Peter Eisentraut]

Package: sasl2-bin
Version: 2.1.22.dfsg1-23
Severity: normal
Tags: patch

Playing around with the sasl-sample-client/sasl-sample-server, I always get 
this:

$ ./sample-client -s test
service=test
Waiting for mechanism list from server...
S: Q1JBTS1NRDUgTE9HSU4gRElHRVNULU1ENSBOVExNIFBMQUlOIEFOT05ZTU9VUw==
lt-sample-client: Decoding data from base64: bad protocol / cancel

A similar report can be found here: 
https://answers.launchpad.net/ubuntu/+source/cyrus-sasl2/+question/60325

The problem turns out to be that the newline at the end of the base64-encoded 
string needs to be stripped off before the string is passed to the decoding 
routine.  According to Debian bug #400955, this was at some point made more 
strict, so it probably worked in an earlier version, but it doesn't anymore.

A simple fix is to change the following lines, identical in sample-server.c 
and sample-client.c, from

  result = sasl_decode64(buf + 3, (unsigned) strlen(buf + 3), buf,
                         SAMPLE_SEC_BUF_SIZE, &len);

to

  result = sasl_decode64(buf + 3, (unsigned) strlen(buf + 3) - 1, buf,
                         SAMPLE_SEC_BUF_SIZE, &len);
 
This assumes that the string always contains a trailing newline, which is 
technically not guaranteed, but should be unlikely.  (The input buf comes from 
fgets().)

With this fix, I could get sasl-sample-client/sasl-sample-server working.