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// Package header can be used to sanitize HTTP request and response headers.
package header
import (
"fmt"
"net/http"
"strings"
)
// Sanitize list of headers.
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ can be consulted for header syntax.
func Sanitize(sanitizers map[string]SanitizeHeaderFunc, headers http.Header) http.Header {
var redacted = http.Header{}
for k, values := range headers {
if s, ok := sanitizers[http.CanonicalHeaderKey(k)]; ok {
redacted[k] = sanitize(s, values)
continue
}
redacted[k] = values
}
return redacted
}
func sanitize(s SanitizeHeaderFunc, values []string) []string {
var redacted = []string{}
for _, v := range values {
redacted = append(redacted, s(v))
}
return redacted
}
// DefaultSanitizers contains a list of sanitizers to be used for common headers.
var DefaultSanitizers = map[string]SanitizeHeaderFunc{
"Authorization": AuthorizationSanitizer,
"Set-Cookie": SetCookieSanitizer,
"Cookie": CookieSanitizer,
"Proxy-Authorization": AuthorizationSanitizer,
}
// SanitizeHeaderFunc implements sanitization for a header value.
type SanitizeHeaderFunc func(string) string
// AuthorizationSanitizer is used to sanitize Authorization and Proxy-Authorization headers.
func AuthorizationSanitizer(unsafe string) string {
if unsafe == "" {
return ""
}
directives := strings.SplitN(unsafe, " ", 2)
l := 0
if len(directives) > 1 {
l = len(directives[1])
}
if l == 0 {
return directives[0]
}
return directives[0] + " " + redact(l)
}
// SetCookieSanitizer is used to sanitize Set-Cookie header.
func SetCookieSanitizer(unsafe string) string {
directives := strings.SplitN(unsafe, ";", 2)
cookie := strings.SplitN(directives[0], "=", 2)
l := 0
if len(cookie) > 1 {
l = len(cookie[1])
}
if len(directives) == 2 {
return fmt.Sprintf("%s=%s; %s", cookie[0], redact(l), strings.TrimPrefix(directives[1], " "))
}
return fmt.Sprintf("%s=%s", cookie[0], redact(l))
}
// CookieSanitizer is used to sanitize Cookie header.
func CookieSanitizer(unsafe string) string {
cookies := strings.Split(unsafe, ";")
var list []string
for _, unsafeCookie := range cookies {
cookie := strings.SplitN(unsafeCookie, "=", 2)
l := 0
if len(cookie) > 1 {
l = len(cookie[1])
}
list = append(list, fmt.Sprintf("%s=%s", cookie[0], redact(l)))
}
return strings.Join(list, "; ")
}
func redact(count int) string {
if count == 0 {
return ""
}
return "████████████████████"
}
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