I'm trying to learn the XMPP spec (RFC 3920) by coding it in low-level Python. But I've been hung up for over an hour at step 4 of section 6.5, selecting an authentication mechanism. I'm sending: <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' mechanism='PLAIN'/>, and getting: <failure xmlns="urn:ietf:params:xml:ns:xmpp-sasl"><incorrect-encoding/></failure> instead of a base64-encoded challenge.
The "incorrect-encoding" error is supposedly to be used for when I incorrectly base64-encode something, but there was no text to encode. I'm probably missing something really obvious. Anybody got a cluestick?
I'm using talk.google.com port 5222 as the server, if that matters. I doubt that it does; this is almost definitely due to my lack of understanding this section of the RFC. And the problem isn't likely my code, other than the way I'm sending this particular stanza, or it would be failing at the previous steps. But for what it's worth, here is the code I've got so far, and the complete log (transcript of the session). Thanks.
First off, RFC 6120 is often more clear than 3920. [updated to point to the RFC as released]
Since you're using SASL PLAIN (see RFC 4616), many servers expect you to send a SASL "initial response" in the auth element, consisting of:
base64(\x00 + utf8(saslprep(username)) + \x00 + utf8(saslprep(password)))
All together, then, your auth element needs to look like this:
<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
mechanism='PLAIN'>AGp1bGlldAByMG0zMG15cjBtMzA=</auth>
For the username "juliet" and the password "r0m30myr0m30".
Related
I'm using DTLS v1.0 to communicate with a server. I'm having some trouble figuring out exactly what to do to generate the certificate verify message. I've been reading the RFCs (DTLSv1.0 and TLS1.1, which DTLS v1.0 is based on) but they're somewhat non-specific when it comes to this particular message.
I see the structure of the message is as below, and I know the signature type is RSA.
struct {
Signature signature;
} CertificateVerify;
The Signature type is defined in 7.4.3.
CertificateVerify.signature.md5_hash
MD5(handshake_messages);
CertificateVerify.signature.sha_hash
SHA(handshake_messages);
Based on what I've read it seems to be a concatenation of the sha1 hash and the md5 hash of all the previous messages sent and received (up to and excluding this one) and then RSA signed.
The piece that's got me a bit confused though is how to assemble the messages to hash them.
Does it use each fragment piece or does it use the re-assembled messages? Also, what parts of the messages does it use?
The RFC for TLS 1.1 says
starting at client hello up to but not including this message,
including the type and length fields of the handshake messages
but what about the DTLS specific parts like message_seq, fragment_offset, and fragment_length, do I include them?
UPDATE:
I have tried doing as the RFC for DTLS 1.2 shows (meaning keeping the messages fragmented, using all the handshake fields including DTLS specific fields, and not including the initial Client Hello or Hello Verify Request messages) but I am still receiving "Bad Signature". I do believe I'm signing properly, so it's my belief that I'm concatenating the data improperly to be signed.
For DTLS 1.2 it is defined. And reading RFC 4347, my impression is, RFC 6347 doesn't differ, it clarifies the calculations.
RFC 6347, 4.2.6. CertificateVerify and Finished Messages
RFC 4347, 4.2.6. Finished Messages
In RFC 821, it says that a reset (RSET) command can be sent after a DATA command and some mail data has been sent:
However, what distinguishes between a mail client sending an RSET command after DATA, and a mail that contains the word "RSET" on a line by itself?
I've checked RFC 5321 as well and I can't see anything that would mitigate or escape this. It does talk about escaping a mail line which starts with a ".", but not "RSET".
The client cannot terminate the mail data transfer with a period on a line by itself or the server will send the partial mail it has been given.
I imagine there's something I've missed in the RFCs, otherwise I can't help thinking that there's either an SMTP command injection attack vector in many implementations, or no-one can ever send a mail with "RSET" on a line by itself (I think people would have noticed).
The keyword here is after I believe. The DATA command is in progress until it is finished with a lone . on a line.
RFC 5321 § 4.1.1.5 (RSET) states "any stored sender, recipients, and mail data MUST be discarded." This refers to the MAIL FROM, RCPT TO, and presumably DATA commands.
However, upon receiving the . following DATA, the message "MUST" be delivered (which may result in a failure but not a partial failure, see § 4.1.1.4). This clears the buffer of everything RSET is supposed to do.
This means RSET merely elicits a 250 OK response from the receiving server (a keep-alive, much like NOOP) and confirms to the sender that there is indeed no saved sender or recipient queued for the next message.
I do not know of a way to interrupt a DATA command to issue a RSET. The only way I know of to do that is to terminate the connection and establish a new one—and, just to be safe in the case of some odd resumption capability, I'd issue an RSET right after the EHLO or HELO (which the spec says is a NOOP). If there were such a way, it should be in RFC 5321 § 4.1.1.4, § 4.1.1.5, and/or § 3.3.
i am currently trying to implement a „simple“ readonly CALDAV-interface for a system. But the synchronization protocol and the CALDAV-clients give me some headaches.
The main test client i use is the macos-calendar (sierra).
The initial handshake (DAV principle, calendar lookup) and inital load of data is working. I get some REPORT:calendar-query requests.
The issue is the incremental sync after initial load. There are two approaches:
Via WebSync-extension (REPORT:sync-collection and sync-token prop)
my main issue here is that provisioning the sync-token from the server is not trivial in my system. Changes and New data is not an issue, but physical deletion (not yet logged in the user context) and changes in the scope of group- and/or role-assignments. Maybe i need to consider to invalidate in complex cases the sync-token and let the client resetup without sync-collection?
A nasty workaround could be to retain the calendar item IDs send to the client and check on each request for their existence and responds if necessary with a not found per deleted/out of scope calendar item. But this would mean i store client-state on the server which doesnt sound right and might be error prone.
Via basic protocal synchronization (respond to REPORT:calendar-query and propfind (depth=1) requests no webdav-sync active)
this is also working already in principle for new and changed data. But the macos-calendar doesnt remove items which are not part the collection response (propfind with depth=1). According to the protocol the client should determine the deleted items and remove them, but it doesnt do it in my case. Any ideas here?
For my system currently it would be ideal to use this approach though the performance might be not the ideal one.
With ios-Calendar i face another issue:
Initial handshake is somehow working as the requests in the network are coming and are answered.
But than a MKCALENDAR request is coming (instead of a calendar-query or propfind for items) which answer with 403 as i also dont provide it in the Allow-header of the options response. the request looks like this:
MKCALENDAR /services/cal/_userid/220EDB4A-F00C-41C9-B78F-10781BBA77E4/ HTTP/1.1
Host: 127.0.0.1:8003
Content-Type: text/xml
User-Agent: iOS/10.0.1 (14A403) dataaccessd/1.0
<?xml version="1.0" encoding="UTF-8"?>
<B:mkcalendar xmlns:B="urn:ietf:params:xml:ns:caldav">
<A:set xmlns:A="DAV:">
<A:prop>
<B:calendar-free-busy-set>
<NO/>
</B:calendar-free-busy-set>
<D:calendar-order xmlns:D="http://apple.com/ns/ical/">1</D:calendar-order>
<A:displayname>Kalender</A:displayname>
<B:calendar-timezone>BEGIN:VCALENDAR
...deleted....
</B:calendar-timezone>
<B:supported-calendar-component-set>
<B:comp name="VEVENT"/>
</B:supported-calendar-component-set>
</A:prop>
</A:set>
</B:mkcalendar>
Nothing is happening afterwards.
Anyone experiencing this as well? Why ios-calendar tries to do a mkcalendar though i have a calendar-collection as resource-type?
With Thunderbird Lightning:
Initial handshake with the calendar-collection is working
A propfind-and multiget request for items is answered with iCal-Items.
But they are not displayed and in the error log i receive:
Warnung: CalDAV: Get failed: CalDAV: Error: got status 200 fetching calendar data for Debug Proxy, null
(text in german: error code: 0x80004005) Warnung: Fehler beim Lesen von Daten für Kalender: Debug Proxy. Allerdings ist dieser Fehler wahrscheinlich vernachlässigbar, daher versucht das Programm fortzufahren. Fehlercode: 0x80004005. Beschreibung: CalDAV: Error: got status 200 fetching calendar data for Debug Proxy, null
(text in german: error code: READ_FAILED) Warnung: Fehler beim Lesen von Daten für Kalender: Debug Proxy. Allerdings ist dieser Fehler wahrscheinlich vernachlässigbar, daher versucht das Programm fortzufahren. Fehlercode: READ_FAILED. Beschreibung:
http channel Listener OnDataAvailable contract violation
a similiar response is though working in macos-calendar – could it be some encoding issue?
Any hints are highly appreciated!
This is indeed a pretty broad question. But let me try to address some stuff:
Via WebSync-extension (REPORT:sync-collection and sync-token prop) my main issue here is that provisioning the sync-token from the server is not trivial in my system
Even if it is hard for you, you should really try to come up with something here. Even if this means storing some extra info on the server. Sync-collection is way more efficient.
(Idea: Maybe you can at least set a flag when something actually got deleted and only then expire the sync-token?)
Via basic protocal synchronization (respond to REPORT:calendar-query and propfind (depth=1))
Which one, calendar-range-query or PROPFIND? Completely different things ...
this is also working already in principle for new and changed data. But the macos-calendar doesnt remove items which are not part the collection response (propfind with depth=1).
If we are talking about a calendar-range-query, the client cannot proactively delete items since it doesn't know whether they just left the range (vs being deleted).
With PROPFIND it should do this. If you have proof it doesn't, maybe create another question with all the relevant details.
With ios-Calendar i face another issue: ... a MKCALENDAR request is coming ...
This probably means that it can't find the default scheduling calendar, no calendar at all, none with a proper component-type property. Or all the same for todos (Reminders app, same account). What is the payload of the MKCALENDAR?
Hard to diagnose w/o details, if you can't figure it out, ask a specific question on this with all the relevant details included (e.g. the XML you send in response to the home query).
Thunderbird Lightning
Can't say much about this, probably depends a lot on the version and what extensions you are using. AFAIK many people use the ScalableOGo Thunderbird extensions to get proper Cal/CardDAV with Thunderbird.
For Thunderbird/Lightning you may want to turn on calendar.debug.log and calendar.debug.log.verbose in the advanced config editor and restart. You can find it in Options > Advanced > General > Config Editor. This will get you more detailed http requests and information about what failed. You can also hook up the remote debugger and look at the network monitor, or set breakpoints in the code.
With Thunderbird/Lightning please note that we are using a mix of previous and current versions of the webdav-sync draft. I can't say much from the error message as is given it is very general, but it does look like there is something unexpected in the results.
Maybe it makes sense to compare the handshake between an existing server (like sabre/dav) and the client, then see where the difference between your communication and theirs is.
Also, you may be interested in the CalDAVTester from Apple, which checks server interoperability. Note however that it does contain various apple specific tests. The folks at CalConnect are working together with Apple to make it more generally usable and to split out the Apple-specific tests. Given your server is read-only, don't expect everything to work, but you can hunt for fixing specific tests.
I want to implement a simple authentication in C++. For now I can initiate a stream, get supported mechanisms and chose one. It works fine, but now I can't read out (from http://xmpp.org/extensions/xep-0034.html#sect-id259287 ) what I have to write into the plaintext handshake. Decoding the string I get "robsecret". So how do I do it with username "user" and passsword "pass"?
PS: Response using "userpass" is "".
Thanks!
You do of course realize that this is a retracted XEP you are trying to find information in?
The relevant documents are RFC 6120 (XMPP Core) and RFC 4616 (SASL PLAIN).
Short version:
PLAIN requires you to send base64("authzid\0authcid\0password"), where authzid is usually empty and authcid is your username.
Making a REST web server mainly based on large files uploads / downloads, I want to be able to check the file integrity. I believed that the proper way to do it was using Content-MD5 HTTP header [0] as proved useful by aws experience [1].
However, much to my dismay, I recently learned that it was (to be ?) deprecated [2].
The deprecation discussion did not give any workaround hint, so I am asking you :
Should I still decide to use a Content-MD5 HTTP header ?
Should I use an ETag with the same meaning (base64 encoding of the md5sum) ?
Should I use an ?md5sum=XXX parameter ?
Is there a better solution altogether ?
Thanks for your insights.
Best Regards,
B.
[0] https://webmasters.stackexchange.com/questions/2924/
[1] http://developer.amazonwebservices.com/connect/thread.jspa?threadID=22709
[2] http://trac.tools.ietf.org/wg/httpbis/trac/ticket/178
Add a custom header, called say X-YourService-Integrity. That makes it explicit that it's a system specific to your service, and allows you to use integrity check mechanisms other than MD5 in the future (for example, SHA1). It also avoids you having to "overload" existing mechanisms that are similar but not quite what you want.
https://www.ietf.org/rfc/rfc3230.txt
4.3.2 Digest
The Digest message header field provides a message digest of the
instance described by the message.
Digest = "Digest" ":" #(instance-digest)
The instance described by a message might be fully contained in the
message-body, partially-contained in the message-body, or not at all
contained in the message-body. The instance is specified by the
Request-URI and any cache-validator contained in the message.
A Digest header field MAY contain multiple instance-digest values.
This could be useful for responses expected to reside in caches
shared by users with different browsers, for example.
A recipient MAY ignore any or all of the instance-digests in a Digest
header field.
A sender MAY send an instance-digest using a digest-algorithm without
knowing whether the recipient supports the digest-algorithm, or even
knowing that the recipient will ignore it.
Examples:
Digest: md5=HUXZLQLMuI/KZ5KDcJPcOA==
Digest: SHA=thvDyvhfIqlvFe+A9MYgxAfm1q5=,unixsum=30637
Do not use Content-MD5: it has been deprecated because it leads to inconsistencies.
Use Digest with sha-256 or sha-512. We are updating RFC3230 to the latest HTTP specification (RFC7231) and added a lot of useful examples https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-digest-headers-02
Digest: sha-256=4REjxQ4yrqUVicfSKYNO/cF9zNj5ANbzgDZt3/h3Qxo=
There Want-Digest allows requesting a specific Digest header.
Eg. The client requests a digest, supporting sha-256 and sha-512. The server replies with sha-256
Request:
GET /items/123 HTTP/1.1
Want-Digest: sha-256, sha-512
Response:
HTTP/1.1 200 OK
Content-Type: application/json
Digest: sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
{"hello": "world"}