I used wireshark to check post request and I found that the reassembled TCP segment size greater than the content-length , is that because content-length is for the size of body only ? and the ressambled includes the header ?
[3 Reassembled TCP Segments (1664 bytes): #1233(578), #1235(1028), #1237(58)]
[Frame: 1233, payload: 0-577 (578 bytes)]
[Frame: 1235, payload: 578-1605 (1028 bytes)]
[Frame: 1237, payload: 1606-1663 (58 bytes)]
[Segment count: 3]
[Reassembled TCP length: 1664]
Hypertext Transfer Protocol
content-length: 1249\r\n
is that because content-length is for the size of body only
Correct. Content-length describes only the length of the message body. From the HTTP standard:
14.13 Content-Length
The Content-Length entity-header field indicates the size of the entity-body, in decimal number of OCTETs ...
... and the ressambled includes the header ?
Given that you show parts of the header which is included in the reassembled data these data obviously contain at least part of the header.
Related
i reading about MAVlink and i try to read packages from pixhawk fly controller.
I thought of another way to make the call and i want to know from this discussions readers if its ok and what are you think
On my reader .. i read the two first byte from the pixhawk.
The second byte need to be the PAYLOAD length --> so new i know that i need to read the 4 bytes of the header + PAYLOAD length bytes + 2 chcksub bytes.
So after reading the PAYLOAD length i define a byte array -> size is
( PAYLOAD.length + 4 + 2 ) and read from the serial to this buffer.
Is it ok to do it ?
The MAVLink protocol has HEADER + PAYLOAD + SIGNATURE format.
MAVLink v1.0
v1.0 is the standard protocol as specified by QGroundControl. It has the format:
6 bytes header
(PAYLOAD length) bytes payload
2 bytes signature (checksum)
The first byte is always the protocol start-of-frame: 0xFE
The second byte is always the payload length.
Hence your receive buffer size should be (PAYLOAD length) + 8.
The method you described will generally work for most packets received from the pixhawk. However, pixhawk (ArduPilot) makes use of an extended MAVLink protocol which has been coined "v2.0" which adds additional header and signature bytes.
MAVLink v2.0
v2.0 is the extended protocol which applies to a select few messages such as "STATUSTEXT". It has the format:
10 bytes header
(PAYLOAD length) bytes payload
15 bytes signature
The first byte has the start-of-frame: 0xFD
The second byte is again the payload length.
Hence, your buffer size should be (PAYLOAD length) + 25.
If you want to process MAVLink message data from the pixhawk, or from the generated .tlog file you should set your input message buffer size based on the start of frame and payload length bytes, the first two bytes of any MAVLink message.
I'm using multirange http requests like this
"curl --range 1-2,2-3 http://some.url"
The response is like
--00000000000000030705 Content-Type: text/html; charset=utf-8 Content-Range: bytes 1-2/13882393
il
--00000000000000030705 Content-Type: text/html; charset=utf-8 Content-Range: bytes 2-3/13882393
le
--00000000000000030705--
How can I remove fields Content-Type and Content-Range from response to get a raw data from server (without parsing on client side)?
I want to get response like:
"ille"
Thanks a lot!
You probably can't. The server is conforming to the spec, as described by the RFC.
If multiple parts are being transferred, the server generating the 206 response must generate a "multipart/byteranges" payload, as defined in Appendix A, and a Content-Type header field containing the multipart/byteranges media type and its required boundary parameter. To avoid confusion with single-part responses, a server must not generate a Content-Range header field in the HTTP header section of a multiple part response (this field will be sent in each part instead).
In the case of contiguous multi ranges the server may send the response without the multipart boundaries but this is optional.
When multiple ranges are requested, a server may coalesce any of the ranges that overlap, or that are separated by a gap that is smaller than the overhead of sending multiple parts, regardless of the order in which the corresponding byte-range-spec appeared in the received Range header field. Since the typical overhead between parts of a multipart/byteranges payload is around 80 bytes, depending on the selected representation's media type and the chosen boundary parameter length, it can be less efficient to transfer many small disjoint parts than it is to transfer the entire selected representation.
Within the header area of each body part in the multipart payload, the server must generate a Content-Range header field corresponding to the range being enclosed in that body part. If the selected representation would have had a Content-Type header field in a 200 (OK) response, the server should generate that same Content-Type field in the header area of each body part. For example:
Assuming your server conforms to the spec, sending a single range 1-3 you will get a single body.
I am learning HTTP. I enclose a request payload in XML or JSON format in my POST requests. What I wanted to know is whether a request payload and request body mean the same thing?
Definition of: payload : The "actual data" in a packet or file minus all headers attached for transport and minus all descriptive meta-data. In a network packet, headers are appended to the payload for transport and then discarded at their destination.
Edit: In Http protocol, an http packet has http headers and http payload.So payload section of http packet may or may not have a body depending upon the type of request (e.g. POST vs GET). So payload and body are not the same thing.
Payload is the "wrapper" to the body
Payload is something one carries. A paperboy's payload is a pile of newspapers and a HTTP POST request's payload is whatever comes in the "body".
What I wanted to know is whether a request payload and request body mean the same thing?
No, they have different meanings. A payload (a.k.a. content) is a part of representation data while a body is a part of a message, which are two different HTTP concepts. A representation (data and metadata) is transferred as a single or multiple messages, so a message encloses a complete or partial representation. The representation metadata are enclosed in the header fields of a message and the representation data, the payload, are enclosed in the body of a message, as is or transfer-encoded.
References
RFC 9110: HTTP Semantics defines the term representation:
3.2. Representations
A "representation" is information that is intended to reflect a past, current, or desired state of a given resource, in a format that can be readily communicated via the protocol. A representation consists of a set of representation metadata and a potentially unbounded stream of representation data (Section 8).
Notice that the definition is independent of the version of HTTP because it is about semantics.
RFC 9112: HTTP/1.1 defines the term message:
2.1. Message Format
An HTTP/1.1 message consists of a start-line followed by a CRLF and a sequence of octets in a format similar to the Internet Message Format [RFC5322]: zero or more header field lines (collectively referred to as the "headers" or the "header section"), an empty line indicating the end of the header section, and an optional message body.
HTTP-message = start-line CRLF
*( field-line CRLF )
CRLF
[ message-body ]
Notice that the definition depends on the version of HTTP because it is about syntax.
RFC 9110: HTTP Semantics defines the term content:
6.4. Content
HTTP messages often transfer a complete or partial representation as the message "content": a stream of octets sent after the header section, as delineated by the message framing.
This abstract definition of content reflects the data after it has been extracted from the message framing. For example, an HTTP/1.1 message body (Section 6 of [HTTP/1.1]) might consist of a stream of data encoded with the chunked transfer coding -- a sequence of data chunks, one zero-length chunk, and a trailer section -- whereas the content of that same message includes only the data stream after the transfer coding has been decoded; it does not include the chunk lengths, chunked framing syntax, nor the trailer fields (Section 6.5).
Note: Some field names have a "Content-" prefix. This is an informal convention; while some of these fields refer to the content of the message, as defined above, others are scoped to the selected representation (Section 3.2). See the individual field's definition to disambiguate.
RFC 9110: HTTP Semantics substitutes the term content for payload used in previous RFCs:
B.3. Changes from RFC 7231
[…]
The terms "payload" and "payload body" have been replaced with "content", to better align with its usage elsewhere (e.g., in field names) and to avoid confusion with frame payloads in HTTP/2 and HTTP/3. (Section 6.4)
Header identifies source & destination of the sent packet, whereas the actual data i.e Body is referred to as Payload
The start-line and HTTP headers of the HTTP message are collectively known as the head of the requests, whereas its payload is known as the body
So Yes, they are the same thing.
Got this from https://developer.mozilla.org/en-US/docs/Web/HTTP/Messages
Payload of HTTP message is known as the body. link1
The HTTP message payload body is the information ("payload") part of the data that is sent in the HTTP Message Body (if any), prior to transfer encoding being applied. If transfer encoding is not used, the payload body and message body are the same thing! link2
So basically the only difference between HTTP message body and HTTP message payload body is encoding (but only if present). So generalizing the term request payload = request body.
I am not grasping the idea behind content-length and byte ranges as specified by HTTP 1.1
Is there are connection between the two of some sort? If a client requests in terms of byte ranges, say 0-100 out of 200, will the first response contain the "content-length" equal to 100 bytes followed by 100 actual data?
Thanks
The Content-Length entity-header field indicates the size of the entity-body […] sent to the recipient […]
In a non-multipart message the entity-body is the body of the HTTP message as it only contains one entity. So the Content-Length value indicates the length of the message body that is sent and not the size of the whole resource.
So for a partial content response on a 0-100 byte range request (first byte and last byte inclusive) the Content-Length of the response will be 0 ≤ size ≤ 101.
In case of a 12345 byte long resource the response could look like this:
HTTP/1.1 206 Partial Content
Content-Range: bytes 0-100/12345
Content-Length: 101
… 101 bytes of content …
How to determine the content-data length if the header is not sent and instead you receive Transfer-Encoding: chunked header?
With chunked encoding there will be no Content-Length header. So after you've read the headers and the pair of CRLFs that mark the end of the headers, you're ready to read the first chunk. Each chunk payload is preceded by its own mini-header - the length in hex followed by CRLF. And there's another CRLF after the payload, before the next chunk's mini-header. A chunk can also be followed by some optional trailers. The end of the message is indicated by a zero-length chunk.
You can find the definitive details in the HTTP RFC, RFC2616.