64e1a813fb
The HTTP middleware and proxy-protocol listeners both pinned trust to exact IPs, which forced re-applying terraform every time AWS rotated an ALB or NLB ENI. Trusted-proxies entries now accept CIDR ranges in addition to plain IPs, so callers can trust whole subnets (where the load balancer ENIs always live) and stop chasing rotating IPs. The HTTP middleware splits parsed entries into IPs and IPNets and checks both. The proxy-protocol listeners switch from TrustProxyHeaderFrom (IP-only, REJECT) to ConnStrictWhiteListPolicy (IP or CIDR, REJECT) which preserves the existing reject-on-unknown semantics. Signed-off-by: Bryan Frimin <bryan@getprobo.com>
101 lines
2.7 KiB
Go
101 lines
2.7 KiB
Go
// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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package trustedproxy
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import (
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"fmt"
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"net"
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"net/http"
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"strings"
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)
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var forwardedHeaders = []string{
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"Forwarded",
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"X-Forwarded-For",
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}
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// NewMiddleware returns an HTTP middleware that strips forwarded
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// headers from requests that did not originate from one of the given
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// trusted proxies. Each entry in trusted may be either a single IP
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// address (e.g. "10.0.0.1") or a CIDR range (e.g. "10.0.0.0/24").
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// When the list is empty every request is treated as untrusted and
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// the headers are always removed. An error is returned if any entry
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// is neither a valid IP nor a valid CIDR.
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func NewMiddleware(trusted []string) (func(http.Handler) http.Handler, error) {
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ips, nets, err := parseTrusted(trusted)
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if err != nil {
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return nil, err
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}
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if !isTrusted(r.RemoteAddr, ips, nets) {
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for _, h := range forwardedHeaders {
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r.Header.Del(h)
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}
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}
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next.ServeHTTP(w, r)
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})
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}, nil
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}
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func parseTrusted(trusted []string) ([]net.IP, []*net.IPNet, error) {
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ips := make([]net.IP, 0, len(trusted))
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nets := make([]*net.IPNet, 0, len(trusted))
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for _, entry := range trusted {
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if strings.Contains(entry, "/") {
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_, ipNet, err := net.ParseCIDR(entry)
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if err != nil {
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return nil, nil, fmt.Errorf("cannot parse CIDR %q: %w", entry, err)
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}
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nets = append(nets, ipNet)
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continue
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}
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ip := net.ParseIP(entry)
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if ip == nil {
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return nil, nil, fmt.Errorf("cannot parse IP address %q", entry)
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}
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ips = append(ips, ip)
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}
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return ips, nets, nil
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}
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func isTrusted(remoteAddr string, ips []net.IP, nets []*net.IPNet) bool {
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host, _, err := net.SplitHostPort(remoteAddr)
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if err != nil {
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host = remoteAddr
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}
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ip := net.ParseIP(host)
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if ip == nil {
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return false
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}
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for _, t := range ips {
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if t.Equal(ip) {
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return true
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}
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}
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for _, n := range nets {
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if n.Contains(ip) {
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return true
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}
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}
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return false
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}
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