Re: Returning error message from custom smart http server
On Sat, May 17, 2014 at 9:01 AM, brian m. carlson
sand...@crustytoothpaste.net wrote:
On Tue, May 13, 2014 at 09:39:59AM +0200, Ákos, Tajti wrote:
Dear List,
we implemented our own git smart http server to be able to check permissions
and other thing before pushes. It works fine, however, the error messages we
generate on the server side are not displayed by the command line client. On
the server we generate error messages like this:
response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
response.getWriter().write(msg);
On the command line we get this:
Total 0 (delta 0), reused 0 (delta 0)
POST git-receive-pack (290 bytes)
efrror: RPC failed; result=22, HTTP code = 401
atal: The remote end hung up unexpectedly
fatal: The remote end hung up unexpectedly
The server message is completely missing. Is there a solution for this?
You should not need a patched git; the wire protocol itself has a
mechanism for sending smart error messages. It's not particularly
_obvious_, but it's there.
For starters, to return an error message, your status must be 200 OK.
You can't return any other status code or Git will interpret your
error as some form of _HTTP_ error rather than a _git_ error.
In the smart protocol the client sends a service to the server as a
query parameter, like ?service=git-receive-pack. For such a request,
you need to:
- Set the content type to application/x-service-advertisement
(e.g. application/x-git-receive-pack-advertisement) (Not all command
line Git versions require this, but JGit does)
- Set the status code as 200 OK
- Write back a payload where the first 4 bytes are the hex-encoded
length of the text (where is max length for a single packet).
Note that the 4 bytes for the size are _part_ of that length, so if
you're writing Test the length is 8, not 4
- After the size, you write # service=service (e.g. #
service=git-receive-pack; note the space after the #) This is the
metadata. For an error, you don't really have much to say.
- After that, an empty packet, which is (four zeros) This
separates the metadata from the ref advertisement
- After that you can write your message, beginning with ERR (note
the trailing space there). The ERR tells Git what you're writing
isn't a ref, it's an error. I'd recommend appending a newline (and add
1 more to your length for it), because when Git echoes your error
message it doesn't seem to do that
I'm not sure whether there's a document that describes all of this; I
found it by digging into the Git source code (you can find the ERR
handling in connect.c, get_remote_heads). This may be exploiting the
protocol, I'll leave that to someone more knowledgeable on how they
_intended_ this all to be used, but it works for us.
A full example looks something like this: 0036#
service=git-receive-packERR This is a test\n
Hope this helps,
Bryan Turner
It does look that way. Does the following patch work for you?
-- 8 --
Subject: [PATCH] http: provide server's error message on RPC failure
The server might provide a custom error message that is useful to the user.
Provide this message to the user if HTTP RPC fails.
Signed-off-by: brian m. carlson sand...@crustytoothpaste.net
---
remote-curl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/remote-curl.c b/remote-curl.c
index 52c2d96..5984d35 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -426,8 +426,8 @@ static int run_slot(struct active_request_slot *slot,
err = run_one_slot(slot, results);
if (err != HTTP_OK err != HTTP_REAUTH) {
- error(RPC failed; result=%d, HTTP code = %ld,
- results-curl_result, results-http_code);
+ error(RPC failed; result=%d, HTTP code = %ld (%s),
+ results-curl_result, results-http_code,
curl_errorstr);
}
return err;
-- 8 --
--
brian m. carlson / brian with sandals: Houston, Texas, US
+1 832 623 2791 | http://www.crustytoothpaste.net/~bmc | My opinion only
OpenPGP: RSA v4 4096b: 88AC E9B2 9196 305B A994 7552 F1BA 225C 0223 B187
--
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Re: Returning error message from custom smart http server
On Mon, 2014-05-19 at 18:12 +1000, Bryan Turner wrote: On Sat, May 17, 2014 at 9:01 AM, brian m. carlson sand...@crustytoothpaste.net wrote: On Tue, May 13, 2014 at 09:39:59AM +0200, Ákos, Tajti wrote: Dear List, we implemented our own git smart http server to be able to check permissions and other thing before pushes. It works fine, however, the error messages we generate on the server side are not displayed by the command line client. On the server we generate error messages like this: response.setStatus(HttpServletResponse.SC_UNAUTHORIZED); response.getWriter().write(msg); On the command line we get this: Total 0 (delta 0), reused 0 (delta 0) POST git-receive-pack (290 bytes) efrror: RPC failed; result=22, HTTP code = 401 atal: The remote end hung up unexpectedly fatal: The remote end hung up unexpectedly The server message is completely missing. Is there a solution for this? You should not need a patched git; the wire protocol itself has a mechanism for sending smart error messages. It's not particularly _obvious_, but it's there. For starters, to return an error message, your status must be 200 OK. You can't return any other status code or Git will interpret your error as some form of _HTTP_ error rather than a _git_ error. In the smart protocol the client sends a service to the server as a query parameter, like ?service=git-receive-pack. For such a request, you need to: - Set the content type to application/x-service-advertisement (e.g. application/x-git-receive-pack-advertisement) (Not all command line Git versions require this, but JGit does) - Set the status code as 200 OK - Write back a payload where the first 4 bytes are the hex-encoded length of the text (where is max length for a single packet). Note that the 4 bytes for the size are _part_ of that length, so if you're writing Test the length is 8, not 4 - After the size, you write # service=service (e.g. # service=git-receive-pack; note the space after the #) This is the metadata. For an error, you don't really have much to say. - After that, an empty packet, which is (four zeros) This separates the metadata from the ref advertisement - After that you can write your message, beginning with ERR (note the trailing space there). The ERR tells Git what you're writing isn't a ref, it's an error. I'd recommend appending a newline (and add 1 more to your length for it), because when Git echoes your error message it doesn't seem to do that I'm not sure whether there's a document that describes all of this; I found it by digging into the Git source code (you can find the ERR handling in connect.c, get_remote_heads). This may be exploiting the protocol, I'll leave that to someone more knowledgeable on how they _intended_ this all to be used, but it works for us. A full example looks something like this: 0036# service=git-receive-packERR This is a test\n This is indeed documented, namely in Documentation/technical/pack-protocol.txt I guess it could do with an example, but your usage seems correct. There are two different places where things could go wrong, either in HTTP, such as authentication, or in the Git part of the request. If you return an HTTP 404, then all you're telling the client is that you couldn't find what it asked for, but that could mean either the receice-pack/upload-pack program or the repository itself. If something went wrong at the Git level, whether it's a resource problem in the server or simply that the repo doesn't exist, then ERR is the right thing to use. Particularly, we can't rely on the HTTP 404 response being anything meaningful, as it could simply be the host's default 404 page, and you don't want html flying through your terminal. Cheers, cmn -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Returning error message from custom smart http server
On Mon, May 19, 2014 at 06:12:10PM +1000, Bryan Turner wrote: For starters, to return an error message, your status must be 200 OK. You can't return any other status code or Git will interpret your error as some form of _HTTP_ error rather than a _git_ error. As of git v1.8.3, git will show text/plain content sent along with a a non-200 HTTP code. However, it does this _only_ for the initial refs fetch (along with several other error-reporting niceties, including specifically handling HTTP 401s). The thinking was that the interesting smart-http errors happen on that initial contact (e.g., failure to login, access denied, etc). Errors at the HTTP level that happen later during POST requests mean that the server is misconfigured or broken somehow, and should be rare. That's the theory anyway. In the original poster's example, it looks like the server is rejecting the push with an HTTP 401 during the POST call, after the initial ref advertisement. This is non-ideal, because it means the client may have gone to significant work to generate the packfile. It should instead reject it as soon as it sees a request for .../info/refs?service=git-receive-pack. Current git clients will prompt for errors, and will also show the text/plain content. - Set the content type to application/x-service-advertisement (e.g. application/x-git-receive-pack-advertisement) (Not all command line Git versions require this, but JGit does) A side note, but command-line Git cares about the content-type since v1.8.1.5. [...how git's ERR lines work...] Your description seemed accurate from my brief read. Sending ERR lines goes back much further. However, for a 401, I think they really want to send the HTTP code (and at the right time), so that the client can recognize this, gather credentials from the user, and try again. -Peff -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Returning error message from custom smart http server
On Tue, May 13, 2014 at 09:39:59AM +0200, Ákos, Tajti wrote:
Dear List,
we implemented our own git smart http server to be able to check permissions
and other thing before pushes. It works fine, however, the error messages we
generate on the server side are not displayed by the command line client. On
the server we generate error messages like this:
response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
response.getWriter().write(msg);
On the command line we get this:
Total 0 (delta 0), reused 0 (delta 0)
POST git-receive-pack (290 bytes)
efrror: RPC failed; result=22, HTTP code = 401
atal: The remote end hung up unexpectedly
fatal: The remote end hung up unexpectedly
The server message is completely missing. Is there a solution for this?
It does look that way. Does the following patch work for you?
-- 8 --
Subject: [PATCH] http: provide server's error message on RPC failure
The server might provide a custom error message that is useful to the user.
Provide this message to the user if HTTP RPC fails.
Signed-off-by: brian m. carlson sand...@crustytoothpaste.net
---
remote-curl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/remote-curl.c b/remote-curl.c
index 52c2d96..5984d35 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -426,8 +426,8 @@ static int run_slot(struct active_request_slot *slot,
err = run_one_slot(slot, results);
if (err != HTTP_OK err != HTTP_REAUTH) {
- error(RPC failed; result=%d, HTTP code = %ld,
- results-curl_result, results-http_code);
+ error(RPC failed; result=%d, HTTP code = %ld (%s),
+ results-curl_result, results-http_code, curl_errorstr);
}
return err;
-- 8 --
--
brian m. carlson / brian with sandals: Houston, Texas, US
+1 832 623 2791 | http://www.crustytoothpaste.net/~bmc | My opinion only
OpenPGP: RSA v4 4096b: 88AC E9B2 9196 305B A994 7552 F1BA 225C 0223 B187
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Description: Digital signature
Returning error message from custom smart http server
Dear List, we implemented our own git smart http server to be able to check permissions and other thing before pushes. It works fine, however, the error messages we generate on the server side are not displayed by the command line client. On the server we generate error messages like this: response.setStatus(HttpServletResponse.SC_UNAUTHORIZED); response.getWriter().write(msg); On the command line we get this: Total 0 (delta 0), reused 0 (delta 0) POST git-receive-pack (290 bytes) efrror: RPC failed; result=22, HTTP code = 401 atal: The remote end hung up unexpectedly fatal: The remote end hung up unexpectedly The server message is completely missing. Is there a solution for this? Thanks, Ákos Tajti --- A levél vírus, és rosszindulatú kód mentes, mert az avast! Antivirus védelme ellenőrizte azt. http://www.avast.com -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
