ipa-join: implement calls to JSON-RPC endpoints

[Carbenium]

Based on work done by @mulatinho in PR #3544

[abbra]

autoheader: warning: missing template: WITH_IPA_JOIN_XML
autoheader: Use AC_DEFINE([WITH_IPA_JOIN_XML], [], [Description])
autoreconf: /usr/bin/autoheader failed with exit status: 1
configure: error: cannot find install-sh, install.sh, or shtool in "." "./.." "./../.."

[tiran]

Excellent work! I'm impressed.

I have marked a couple of places where NULL or error checks are missing. Explicit error checking in C is a PITB. :(

Normally I wouldn't bee too concerned with memory leaks in short-running binaries. But our internal build systems and QA has static code analyzers that will flag any potential leak.

[Carbenium]

@rcritten @tiran Thanks for the reviews so far! It's been a while I had been in contact with C...

I think/hope I addressed all your comments - if you want to have another go.
JSON-RPC based unenrollment is now implemented as well, so xmlrpc is completely optional.

[tiran]

clang code analyzer doesn't four lines of code:

$ scan-build make
...
ipa-join.c:690:34: warning: Result of 'malloc' is converted to a pointer of type 'char', which is incompatible with sizeof operand type 'char *'
    response->payload = (char *) malloc(sizeof(response->payload));
                         ~~~~~~  ^~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~
ipa-join.c:941:9: warning: Branch condition evaluates to a garbage value
    if (cb.payload)
        ^~~~~~~~~~
ipa-join.c:1026:9: warning: Branch condition evaluates to a garbage value
    if (cb.payload)
        ^~~~~~~~~~
ipa-join.c:1400:9: warning: Value stored to 'krberr' is never read
        krberr = krb5_cc_initialize(krbctx, ccache, creds.client);
        ^        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 warnings generated.

[Carbenium]

@tiran Issues found by clang are fixed. I'm going to move the fixes to the respective commits once you reviewed them.

[abbra]

checking for JANSSON... yes
checking for LIBCURL... no
configure: error: Package requirements (libcurl) were not met:
Package 'libcurl', required by 'virtual:world', not found
Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.
Alternatively, you may set the environment variables LIBCURL_CFLAGS
and LIBCURL_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
error: Bad exit status from /var/tmp/rpm-tmp.wJxFjt (%build)
RPM build errors:
    Bad exit status from /var/tmp/rpm-tmp.wJxFjt (%build)
Child return code was: 1

[rcritten]

@Carbenium Can you rebase this against the current master? CI is failing because some code that controls template versions is out-of-date.

[Carbenium]

@rcritten Sure thing. Here you go.

[fcami]

/AzurePipelines run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[fcami]

Triggering Azure CI + PR-CI as the Azure failure is unrelated to the PR.

[fcami]

/AzurePipelines run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[rcritten]

All tests are passing, this looks good to me. Last chance @abbra @tiran any final comments before I ack?

[abbra]

LGTM.

So this is going to be a change in defaults: we would default to using JSON-RPC now unless configure --with-ipa-join-xml would be done explicitly.

I think it is worth to document in the release notes (add 'changelog' entry in the ticket') because this client would not be able to enroll to very old servers (IPA v2.x?). No practical change to anything else, though.

[abbra]

master:

• 6e414d2 ipa-join: allowing call with jsonrpc into freeipa API
• 5e7e4f0 ipa-join: don't set TLS related curl options for JSON-RPC
• c197918 ipa-join: improve curl error handling in JSON-RPC code
• c905f94 ipa-join: buffer curl response before parsing json
• 25205f4 ipa-join: switch to jansson for json handling
• 677659c ipa-join: extract unenrollment code common to JSON and XML-RPC to separate function
• 62503e4 ipa-join: implement JSON-RPC based unenrollment
• f694077 ipa-join: select {JSON,XML}-RPC at build time
• a1b117a ipa-join: Use bool type where appropriate
• 7cc977b ipa-join: Generalize XML-RPC references in man page