checker-http/checker/headers.go

130 lines
3.5 KiB
Go

// This file is part of the happyDomain (R) project.
// Copyright (c) 2020-2026 happyDomain
// Authors: Pierre-Olivier Mercier, et al.
package checker
import (
"strconv"
"strings"
)
// HSTSDirectives is the parsed form of a Strict-Transport-Security header
// (RFC 6797 §6.1).
type HSTSDirectives struct {
MaxAge int64
IncludeSub bool
Preload bool
}
// ParseHSTS pulls max-age, includeSubDomains and preload out of an HSTS
// value. Returns nil for an empty value so callers can distinguish "header
// absent" from "header present with max-age=0".
func ParseHSTS(v string) *HSTSDirectives {
v = strings.TrimSpace(v)
if v == "" {
return nil
}
h := &HSTSDirectives{}
for _, part := range strings.Split(v, ";") {
part = strings.TrimSpace(part)
switch {
case strings.HasPrefix(strings.ToLower(part), "max-age="):
val := strings.Trim(part[len("max-age="):], "\"")
if n, err := strconv.ParseInt(val, 10, 64); err == nil {
h.MaxAge = n
}
case strings.EqualFold(part, "includeSubDomains"):
h.IncludeSub = true
case strings.EqualFold(part, "preload"):
h.Preload = true
}
}
return h
}
// CSPDirectives is the parsed form of a Content-Security-Policy header
// (W3C CSP3). Directive names are lowercased; source tokens keep their
// original casing because keywords like 'unsafe-inline' must round-trip
// verbatim when reported back to the user.
type CSPDirectives struct {
Raw string
Directives map[string][]string
}
// ParseCSP splits a CSP header into its directive → sources map.
func ParseCSP(v string) *CSPDirectives {
v = strings.TrimSpace(v)
if v == "" {
return nil
}
c := &CSPDirectives{Raw: v, Directives: map[string][]string{}}
for _, d := range strings.Split(v, ";") {
d = strings.TrimSpace(d)
if d == "" {
continue
}
fields := strings.Fields(d)
name := strings.ToLower(fields[0])
c.Directives[name] = fields[1:]
}
return c
}
// HasDirective reports whether the named directive is declared at all.
func (c *CSPDirectives) HasDirective(name string) bool {
if c == nil {
return false
}
_, ok := c.Directives[strings.ToLower(name)]
return ok
}
// HasSource reports whether the named directive lists the given source
// token (case-insensitive comparison; pass keywords with their quotes,
// e.g. "'unsafe-inline'").
func (c *CSPDirectives) HasSource(directive, source string) bool {
if c == nil {
return false
}
for _, s := range c.Directives[strings.ToLower(directive)] {
if strings.EqualFold(s, source) {
return true
}
}
return false
}
// HasUnsafe reports whether any directive uses 'unsafe-inline' or
// 'unsafe-eval' — the two keywords that nullify most of CSP's value.
func (c *CSPDirectives) HasUnsafe() bool {
if c == nil {
return false
}
for _, sources := range c.Directives {
for _, s := range sources {
ls := strings.ToLower(s)
if ls == "'unsafe-inline'" || ls == "'unsafe-eval'" {
return true
}
}
}
return false
}
// ParsedHeaders bundles the structured headers we parse repeatedly. Fields
// are nil when the underlying header is absent on the probe; rules can
// nil-check or rely on the typed accessors which already handle nil.
type ParsedHeaders struct {
HSTS *HSTSDirectives
CSP *CSPDirectives
}
// ParseHeaders builds a ParsedHeaders from a probe's raw header map.
// Header lookups use the lowercase keys produced by the collector.
func ParseHeaders(p HTTPProbe) ParsedHeaders {
return ParsedHeaders{
HSTS: ParseHSTS(p.Headers["strict-transport-security"]),
CSP: ParseCSP(p.Headers["content-security-policy"]),
}
}