Consistency of headers

[c-f]

Hi everyone,

it's kinda odd to ask a RFC question in a rawHTTP lib :D but maybe other devs might run in the same pitfall.

I'm currently migrating some tools to your version of rawhttp and during testing i noticed a different behaviour in regards to header handling.

Headers will be created without space after the colon:

GET /lelelelelelelel HTTP/1.1
User-Agent:Mozilla/5.0 (Windows NT 10.0; Win64; x63) AppleWebKit/537.63 (KHTML, like Gecko) Chrome/79.0.3945.88 Safari/537.77
Accept:*/*
Host: 127.0.0.1:1337

Reason for this is the WriteHeader, which is used when performing the DoRaw function (https://pkg.go.dev/github.com/projectdiscovery/rawhttp#Client.DoRaw.

Code

rawhttp/client/writer.go

Line 71 in 84c18ae

_, err = fmt.Fprintf(w, "%s:%s\r\n", key, value)

rawhttp/util.go

Line 154 in 391d034

b.WriteString(fmt.Sprintf("%s:%s"+client.NewLine, header.Key, header.Value))

I know that linear white spaces are not required by the RFC (https://datatracker.ietf.org/doc/html/rfc2616#section-4.2), but a single Space is typically used by all sort of http clients e.g. golang (https://cs.opensource.google/go/go/+/refs/tags/go1.18:src/net/http/header.go;l=207).

The field value MAY be preceded by any amount of LWS, though a single SP is preferred. (https://datatracker.ietf.org/doc/html/rfc2616#section-4.2)

Discussion

I would suggest a (breaking ?!) change for the WriteHeader to add a space after the colon, because of the following reasons:

• Confusion: Developer do not expect the behaviour (or at least i did not)
• Consistency: Additional header (host) will be added with a colon:

  rawhttp/client.go

  Line 122 in 391d034

  headers["Host"] = []string{fmt.Sprintf(" %s", host)}

Let me know what you think and thanks again for the work :)

Best regards,
c-f