lör 2014-07-19 klockan 11:35 -0600 skrev Alex Rousskov: > The above email is talking about a "nnCoection: close" header which > appears to be a result of a bug in some 15-year old software. > Identifying that rare header would be overall harmful -- Squid would > spend more resources on detecting that header presence than it will save > by removing that header when it is found.
Indeed a valid question. HTTP divides headers in two groups. end-to-end and hop-by-hop. Assuming we intend to operate as a semantically transparent HTTP proxy (meaing one that do not change the meaning of requests/responses) then we MUST NOT touch end-to-end headers. The list of hop-by-hop headers is very short. Anything not in that list is by definition end-to-end unless mentioned in Connetion. > There are some gray areas like defense against request smuggling, but > even there extreme care should be taken to avoid harming valid HTTP > traffic. It is certainly not the area of "delete all bad headers in the > parser" solutions. request/response smuggling is different. request/response smuggling uses incorrectly/ambigiously formatted HTTP to try to make different agents parse the data stream differently. As for bandwidth savings then dropping "considered useless" headers will do very little on bandwidth savings and risk cause a lot of grief. Much higher bandwidth savings can be acheived by header compression using a dictionary, but that requires supporting agents on both sides of the link. Regards Henrik
