3.1. Range
server May 忽略或者拒绝Range header的情况
A server that supports range requests MAY ignore or reject a Range
header field that consists of more than two overlapping ranges, or a
set of many small ranges that are not listed in ascending order,
since both are indications of either a broken client or a deliberate
denial-of-service attack (Section 6.1).
server可以(MAY)忽略或者拒绝 Range Header 当:
- more than two overlapping ranges
- a set of many small ranges that are not listed in ascending order
注意，这里是忽略或者拒绝2种选择。
client不应该发送包含多个range当请求。
A client SHOULD NOT request
multiple ranges that are inherently less efficient to process and
transfer than a single range that encompasses the same data
Range Header只能被包含在GET请求中
The "Range" header field on a GET request modifies the method
semantics to request transfer of only one or more subranges of the
selected representation data, rather than the entire selected
representation data
Range Header可以被包含在GET request中.
A server MUST ignore a Range header field received with a request method other
than GET.
server会忽略method不是GET的request中的Range Header。
evaluated Range header的唯一情况
The Range header field is evaluated after evaluating the precondition
header fields defined in [RFC7232], and only if the result in absence
of the Range header field would be a 200 (OK) response. In other
words, Range is ignored when a conditional GET would result in a 304
(Not Modified) response.
- 节选中的request的method是GET。因为Range header只能和GET一起使用
- “is evaluated after evaluating the precondition header fields defined in [RFC7232], and only if the result in absence of the Range header field would be a 200 (OK) response.”这段定义了唯一evaluate Range Header的情况：如果把这个GET请求中的RangeHeader去掉以后，服务器应该返回一个200 response(这意味着，所有参与验证的precondition都通过)。那么服务器在原本的GET请求时，会在evaluating the precondition之后evaluate Range Header。
- “In other words, Range is ignored when a conditional GET would result in a 304 (Not Modified) response.”这是对“唯一情况”以外的的其中一种情况的举例。
