3 ms·
I find the writing here confusing. This is what I understand, please correct me if I'm wrong. The URG field is currently used to smuggle urgent data in its va
by gjem97 9y ago
I find the writing here confusing. This is what I understand, please correct me if I'm wrong. The URG field is currently used to smuggle urgent data in its value, whereas the spec says that it should be used to mark the end (and beginning) of an "urgent region" of data on the stream?
- Jasper_ 9y agoLet me try a more concise explanation. There's two separate fields in a TCP packet header: the 1-bit URG flag, and the 16-bit Urgent Pointer. The spec says that "when URG is set, the Urgent Pointer has meaning", and means to "put the user into urgent mode", and points to an index of the stream at some point in the future. When the user reads the data at that index, signal the user to return to normal mode. Because the wording was confusing in the original spec, everyone interpreted this as "there's a special byte at index which is considered 'urgent data'". Popular implementations removed it from the stream entirely and placed it in a special out-of-order bucket.
- deleted 9y ago[deleted]