<6 bytes HTTP responses "vanish"

[bagder]

I did this

$ nc -l -p 8080 -c "echo moom" &
[1] 28461
$ curl localhost:8080 -o dump
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
curl: (56) Recv failure: Connection reset by peer

The zeros in all columns is what's notable. The server sent 5 bytes. Adding -i doesn't help, the 5 bytes are not to be seen; they are not stored in the output file.

I expected the following

Not sure.

curl has support for "HTTP/0.9" which is header-less and is just a response-body until connection close. But since curl doesn't know what HTTP version that comes, it buffers the data to check the first header line. This small amount of data never gets checked since the code wants >5 bytes before it checks.

Since it never qualifies as a header, it should probably be considered a body and get delivered as such when it reaches the end of the transfer without confirming it to be a header.

curl/libcurl version

git master, but this is ancient bug. Presumably this is not an actual problem to many users.

operating system

doesn't matter

[danielgustafsson]

Given how rare it will be in the wild compared to broken servers, is it reasonable to assume HTTP/0.9 unless explicitly specified? That being said, there is no --http0.9 command line switch (and it seems a bit excessive to add).

[bagder]

I would say that most users probably don't even think of HTTP/0.9 and will be surprised when curl would handle such responses.

While --http0.9 seems a bit weird to add at this point, I still think that's the best way forward for this...

[danielgustafsson]

On 19 Apr 2018, at 21:21, Daniel Stenberg ***@***.***> wrote: I would say that most users probably don't even think of HTTP/0.9 and will be surprised when curl would handle such responses. While --http0.9 seems a bit weird to add at this point, I still think that's the best way forward for this…

I think so too. Unless you’re already on it, I can take a stab at it for the next window.

[bagder]

Please have a go at it! The only thing I've done on this is the recipe mentioned above that reproduces the problem...