httputils

The httputils package provides small helpers for parsing HTTP headers and status-code expressions used by command-line flags, environment variables, and configuration files.

Features

• Parse HTTP status codes and ranges such as 200,300-302,404.
• Parse Key=Value header entries into http.Header.
• Canonicalize HTTP header names.
• Preserve duplicate header values when explicitly allowed.
• Preserve commas and additional = characters inside header values.

Installation

go get github.com/containeroo/httputils@latest

Usage

ParseStatusCodes

package main

import (
    "fmt"
    "log"

    "github.com/containeroo/httputils"
)

func main() {
    statusCodes, err := httputils.ParseStatusCodes("200,300-302,404")
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(statusCodes)
}

Output:

[200 300 301 302 404]

ParseHeaders

Pass each header as a separate entry. This avoids treating commas inside valid header values as separators.

package main

import (
    "fmt"
    "log"

    "github.com/containeroo/httputils"
)

func main() {
    headers, err := httputils.ParseHeaders([]string{
        "Content-Type=application/json",
        "Accept=text/html, application/json",
        "X-Trace=one",
        "X-Trace=two",
    }, true)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(headers.Get("Content-Type"))
    fmt.Println(headers.Get("Accept"))
    fmt.Println(headers.Values("X-Trace"))
}

Output:

application/json
text/html, application/json
[one two]

ParseHeaders canonicalizes header names using net/http. When allowDuplicates is false, repeated names are rejected case-insensitively. When it is true, all values are retained in the returned http.Header.

Error handling

ParseStatusCodes and ParseHeaders return errors for malformed input, including invalid status expressions, missing header separators, empty header names, and disallowed duplicate headers.