bastion 0.56.0

client-go/egress.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"io"
 	"net"
+	"net/http"
 	"strings"
 	"time"
 )
@@ -24,94 +25,110 @@ type egressDialer func(ctx context.Context, network, addr string) (net.Conn, err
 // egress is refused (403, before any dial) unless its pairing grant carries
 // the "egress" cap: this lane makes requests leave THIS machine's connection
 // under its address, and nothing in the mgmt op table gates it.
-func handleEgressConn(client net.Conn, dialOut egressDialer, self string) {
+//
+// It reports whether it took the job: true once the request passed every check
+// and was dialled out, whatever the destination then answered; false when the
+// worker closed before a request, or the request was malformed or refused. The
+// worker pool (runEgressWorkers) parks again at once after a job it took, and
+// waits after one it did not.
+func handleEgressConn(client net.Conn, dialOut egressDialer, self string) bool {
 	defer client.Close()
-	br := bufio.NewReader(client)
+	// The request line and headers are read under a bound, the one Go's own HTTP
+	// server uses (http.DefaultMaxHeaderBytes, 1 MiB): the host sends them, and a
+	// head that never ends must not grow in this machine's memory.
+	headLim := &io.LimitedReader{R: client, N: egressMaxHeadBytes}
+	br := bufio.NewReader(headLim)
 	line, err := br.ReadString('\n')
 	if err != nil {
-		return
+		return false
 	}
 	parts := strings.Fields(strings.TrimSpace(line))
 	if len(parts) < 2 {
-		return
+		return false
 	}
 	method, target := parts[0], parts[1]
 
-	// Buffer the head so a plain-HTTP request can be replayed verbatim; capture Host.
+	// Buffer the head: a plain-HTTP request is parsed from it and rebuilt
+	// (parseEgressRequest), never replayed verbatim.
 	var head strings.Builder
 	head.WriteString(line)
-	hostHdr := ""
 	for {
 		h, err := br.ReadString('\n')
 		if err != nil {
-			return
+			return false
 		}
 		head.WriteString(h)
 		if h == "\r\n" || h == "\n" {
 			break
 		}
-		if len(h) >= 5 && strings.EqualFold(h[:5], "host:") {
-			hostHdr = strings.TrimSpace(h[5:])
-		}
 	}
 
+	// The head is in; what follows is the stream itself, unbounded. What the
+	// reader already buffered past the head stays first in line.
+	headLim.N = 1<<63 - 1
+
 	if why := capsAllow(self, "egress"); why != "" {
-		_, _ = client.Write([]byte("HTTP/1.1 403 Forbidden\r\nContent-Length: 0\r\nX-Privatae-Refused: " + why + "\r\n\r\n"))
-		return
+		writeEgressRefusal(client, "403 Forbidden", why, why)
+		return false
 	}
 
 	ctx, cancel := context.WithTimeout(context.Background(), egressDialTimeout)
 	defer cancel()
 
 	if strings.EqualFold(method, "CONNECT") {
-		dialAddrs, why := egressVettedAddrs(ctx, ensurePort(target, "443"))
+		// The target is read the way the Host's egress gate reads it
+		// (parseEgressAuthority): userinfo, an unbracketed IPv6 literal or a
+		// malformed port is refused, never guessed at.
+		host, port, ok := parseEgressAuthority(target, 443)
+		if !ok {
+			writeEgressRefusal(client, "400 Bad Request", egressNoHost, egressNoHost)
+			return false
+		}
+		dialAddrs, why := egressVettedAddrs(ctx, egressHostPort(host, port))
 		if why != "" {
-			_, _ = client.Write([]byte("HTTP/1.1 403 Forbidden\r\nContent-Length: 0\r\nX-Privatae-Refused: " + why + "\r\n\r\n"))
-			return
+			writeEgressRefusal(client, "403 Forbidden", why, why)
+			return false
 		}
 		upstream, err := dialEach(ctx, dialOut, dialAddrs)
 		if err != nil {
-			_, _ = client.Write([]byte("HTTP/1.1 502 Bad Gateway\r\nContent-Length: 0\r\n\r\n"))
-			return
+			writeEgressRefusal(client, "502 Bad Gateway", egressUnreachable, "")
+			return true
 		}
 		if _, err := client.Write([]byte("HTTP/1.1 200 Connection established\r\n\r\n")); err != nil {
 			_ = upstream.Close()
-			return
+			return true
 		}
 		splice(br, client, upstream)
-		return
+		return true
 	}
 
-	// Plain HTTP, absolute-form: "GET http://host/path HTTP/1.1".
-	host := hostHdr
-	if i := strings.Index(target, "://"); i >= 0 {
-		rest := target[i+3:]
-		if s := strings.IndexByte(rest, '/'); s >= 0 {
-			host = rest[:s]
-		} else {
-			host = rest
-		}
+	// Plain HTTP: ONE request per connection, parsed and rebuilt so the
+	// destination reads the host, port and body the lane vetted, sent with
+	// `Connection: close` (egress_http.go). Anything the Host sends after that
+	// request's body closes the connection unforwarded: a keep-alive connection
+	// can no longer carry later requests past the vetting.
+	req, refused := parseEgressRequest(head.String())
+	if refused != nil {
+		writeEgressRefusal(client, refused.status, refused.body, refused.body)
+		return false
 	}
-	if host == "" {
-		return
-	}
-	dialAddrs, why := egressVettedAddrs(ctx, ensurePort(host, "80"))
+	dialAddrs, why := egressVettedAddrs(ctx, egressHostPort(req.host, req.port))
 	if why != "" {
-		_, _ = client.Write([]byte("HTTP/1.1 403 Forbidden\r\nContent-Length: 0\r\nX-Privatae-Refused: " + why + "\r\n\r\n"))
-		return
+		writeEgressRefusal(client, "403 Forbidden", why, why)
+		return false
 	}
 	upstream, err := dialEach(ctx, dialOut, dialAddrs)
 	if err != nil {
-		_, _ = client.Write([]byte("HTTP/1.1 502 Bad Gateway\r\nContent-Length: 0\r\n\r\n"))
-		return
+		writeEgressRefusal(client, "502 Bad Gateway", egressUnreachable, "")
+		return true
 	}
-	if _, err := upstream.Write([]byte(head.String())); err != nil {
-		_ = upstream.Close()
-		return
-	}
-	splice(br, client, upstream)
+	oneEgressExchange(br, client, upstream, req)
+	return true
 }
 
+// egressMaxHeadBytes bounds an egress request's line and headers together.
+const egressMaxHeadBytes = http.DefaultMaxHeaderBytes
+
 // ensurePort returns host:port, adding defPort when target has no explicit port.
 func ensurePort(target, defPort string) string {
 	target = strings.TrimSpace(target)
@@ -157,11 +174,14 @@ func splice(clientReader io.Reader, client, upstream net.Conn) {
 // included), and any address the machine takes as its own (ownaddr.go), such
 // as a public one on its NIC or a range a `local` route delivers here.
 //
-// What differs is the network around it. On an ANCHORED box the lane reaches
-// the public internet and nothing else: private, CGNAT and reserved addresses
-// (the LAN, the mesh) are refused too. On a LOCAL box the LAN stays reachable:
-// the host there is the one the person paired, and their own network is
-// theirs to reach.
+// The network around it is refused too, on every box: the lane reaches the
+// public internet and nothing else, so private, CGNAT and reserved addresses
+// (the LAN, the mesh) are refused, by address and by any address a name
+// resolves to. A LOCAL box used to keep its LAN reachable here; it no longer
+// does (2026-10-26): the Host's egress gate holds every dial it makes to the
+// same rule, and a person's own machines
+// are reached through their approved lanes, never through egress. Only the
+// wording differs between the two kinds of box.
 //
 // Resolution failures refuse too: a name this box cannot resolve is not one
 // it can vouch for.
@@ -245,6 +265,19 @@ func egressVettedAddrs(ctx context.Context, hostport string) ([]string, string)
 		}
 		return nil, "refused: egress to " + host + " — that is this machine; this lane never reaches this machine"
 	}
+	// The network around this machine, on a local box as on an anchored one
+	// (above): any one address of the name that is not the public internet
+	// refuses it. Checked after this machine's own addresses, so those keep
+	// saying "that is this machine".
+	if !anchored {
+		for _, ip := range addrs {
+			if internalIP(ip) {
+				return nil, "refused: egress to " + host + " (" + ip.String() + ") — this lane reaches the " +
+					"public internet only, never this machine's network or the mesh; reach your own " +
+					"machines through their approved lanes"
+			}
+		}
+	}
 	out := make([]string, 0, len(addrs))
 	for _, ip := range addrs {
 		out = append(out, net.JoinHostPort(ip.String(), port))