Apply the new configuration to UDP sessions and kept-alive requests

UDP sessions check for a reload in udpsockmap() as TCP connections do
in sockmap(): unless noforce, a session goes by the newest service on
its listener, re-authenticated as its client, or is dropped.

A request on a connection that outlives a reload, an HTTP one kept
alive, is authorized by clientauth(): it moves the connection to the
newest service on its listener first if a reload came since, then
authorizes as the service whose rules apply (PSRV). The proxy uses it
for every request, so a request of a user the new configuration
removed is answered 407 rather than authorized by the old rules and
cut while relayed. reattach() takes whether to authenticate: sockmap()
and udpsockmap() move and authenticate at once, clientauth() moves and
then authorizes the request.

A test case covers the drops: with one slot free in the new service one
of two downloads moves on and the other is cut (27; a service keeps one
of its maxconn slots for the next connection it accepts), and a proxy
download is cut when a socks service takes its port (26). The reload
case checks the kept-alive request.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/common.c

@@ -233,7 +233,26 @@ struct extparam confboot = {
    whatever runs meanwhile without a service of its own. */
 struct extparam *conf = &confboot;
 struct extparam *runconf = &confboot;
-int (*reattachfunc)(struct clientparam *param) = NULL;
+int (*reattachfunc)(struct clientparam *param, int auth) = NULL;
+
+/* Authorizes a request on a connection which may outlive a reload, an HTTP
+   one kept alive: as a client of the service whose rules apply now, the
+   newest one on its listener after a reload (unless noforce). */
+int clientauth(struct clientparam *param){
+	struct srvparam *orig;
+	int res;
+
+	if(param->version < runconf->version){
+		if(param->srv->noforce || !reattachfunc) param->version = runconf->version;
+		else if((res = (*reattachfunc)(param, 0))) return res;
+	}
+	if(!param->newsrv) return (*param->srv->authfunc)(param);
+	orig = param->srv;
+	param->srv = param->newsrv;
+	res = (*param->srv->authfunc)(param);
+	param->srv = orig;
+	return res;
+}
 _3proxy_mutex_t confref_mutex;
 
 

src/proxy.c

@@ -641,7 +641,7 @@ for(;;){
 
 
  if(param->srv->needuser > 1 && !*param->username) {RETURN(4);}
- if((res = (*param->srv->authfunc)(param))) {
+ if((res = clientauth(param))) {
 	if (res <= 10 || haveconnection || param->transparent) RETURN(res);
 	param->srv->so._closesocket(param->sostate, param->remsock);
 	param->remsock = INVALID_SOCKET;
@@ -649,7 +649,7 @@ for(;;){
 	param->redirtype = 0;
 	memset(&param->sinsl, 0, sizeof(param->sinsl));
 	memset(&param->sinsr, 0, sizeof(param->sinsr));
-	if((res = (*param->srv->authfunc)(param))) RETURN(res);
+	if((res = clientauth(param))) RETURN(res);
  }
 
 

src/proxy.h

@@ -400,9 +400,10 @@ void freeauth(struct auth *);
 void freefilter(struct filter *filter);
 void freeconf(struct extparam *confp);
 void confbegin(void);
-int reattach(struct clientparam *param);
+int reattach(struct clientparam *param, int auth);
 /* reattach() where configurations are reloaded, NULL elsewhere */
-extern int (*reattachfunc)(struct clientparam *param);
+extern int (*reattachfunc)(struct clientparam *param, int auth);
+int clientauth(struct clientparam *param);
 struct passwords * copypwl (struct passwords *pwl);
 void freepwl(struct passwords *pw);
 int copyfilter(struct filter *, struct srvparam *srv);

src/proxymain.c

@@ -1653,13 +1653,13 @@ static void slotrelease(struct srvparam *srv){
 
 /* After a reload, unless noforce: a client goes by the rules of the newest
    service on its listener, the one now accepting there, re-authenticated
-   as it. It takes one of that service's maxconn slots, which counts it
-   there and keeps the service, and its configuration, until the client is
-   done; a slot it held in a service before is given back. 0 to go on, or
-   the code to end the connection with: 26 if its service was removed, or
-   is another one now, 27 if the newest has no slot free, or what the
-   authentication says. */
-int reattach(struct clientparam *param){
+   as it if auth is set. It takes one of that service's maxconn slots,
+   which counts it there and keeps the service, and its configuration,
+   until the client is done; a slot it held in a service before is given
+   back. 0 to go on, or the code to end the connection with: 26 if its
+   service was removed, or is another one now, 27 if the newest has no slot
+   free, or what the authentication says. */
+int reattach(struct clientparam *param, int auth){
  struct srvparam *cur = PSRV(param), *newest, *orig;
  int version = runconf->version, res;
 
@@ -1689,6 +1689,7 @@ int reattach(struct clientparam *param){
  if(param->newsrv) slotrelease(param->newsrv);
  param->newsrv = newest;
  param->version = version;
+ if(!auth) return 0;
  /* authenticated as the newest service's client: its access lists, users,
     limits and counters */
  orig = param->srv;

src/sockmap.c

@@ -271,7 +271,7 @@ log(logbuf);
 	/* a reload: the client goes by the newest configuration's rules */
 	if(param->version < runconf->version){
 		if(param->srv->noforce || !reattachfunc) param->version = runconf->version;
-		else if((res = (*reattachfunc)(param)) && res != 2) {RETURN(res);}
+		else if((res = (*reattachfunc)(param, 1)) && res != 2) {RETURN(res);}
 	}
 
 	if((param->maxtrafin64 && param->statssrv64 >= param->maxtrafin64) || (param->maxtrafout64 && param->statscli64 >= param->maxtrafout64)){

src/udpsockmap.c

@@ -215,6 +215,13 @@ int udpsockmap(struct clientparam *param, int timeo)
 		if (res < 0) return 481;
 		if (res == 0) return 92;
 
+		/* a reload: the session goes by the newest configuration's rules,
+		   as a TCP connection does in sockmap() */
+		if (param->version < runconf->version) {
+			if (param->srv->noforce || !reattachfunc) param->version = runconf->version;
+			else if ((len = (*reattachfunc)(param, 1)) && len != 2) return len;
+		}
+
 		/* datagram from client */
 		if (p.cli >= 0 && p.fds[p.cli].revents) {
 			unsigned char *base = param->srvbuf + UDPHDROFF;

tests/cases/reattach.py

@@ -0,0 +1,83 @@
+"""Connections of old services after a reload (unless noforce): each goes by
+the rules of the newest service on its listener, taking one of its maxconn
+slots, and is dropped where that cannot be."""
+
+import threading
+import time
+
+
+def run(t):
+    origin = t.free_port()
+    proxy = t.free_port()
+    adm = t.free_port()
+
+    def config(service_line, maxconn=50):
+        return f"""
+            log
+            auth iponly
+            allow *
+            http data * /data
+            httpsrv -p{origin}
+
+            flush
+            maxconn {maxconn}
+            auth iponly
+            allow *
+            {service_line}
+
+            flush
+            maxconn 50
+            auth iponly
+            allow *
+            admin -p{adm}
+        """
+
+    server = t.start("reattach", config(f"proxy -p{proxy}"), ports=[origin, proxy, adm])
+
+    def reload(conf):
+        before = server.output().count("Accepting connections")
+        t.write_config("reattach", conf)
+        t.http(f"http://127.0.0.1:{adm}/R")
+        deadline = time.time() + 10
+        while time.time() < deadline and server.output().count("Accepting connections") < before + 3:
+            time.sleep(0.05)
+
+    def downloads(n):
+        """n downloads of about two seconds each through the proxy, started
+        now; the results fill in as they finish."""
+        results = [{} for _ in range(n)]
+
+        def one(r):
+            got = t.http(f"http://127.0.0.1:{origin}/data?size=2000000&block=65536&delay=60",
+                         proxy=f"127.0.0.1:{proxy}")
+            r["length"] = got.length
+
+        threads = [threading.Thread(target=one, args=(r,)) for r in results]
+        for th in threads:
+            th.start()
+        time.sleep(0.4)
+        return threads, results
+
+    # --- the newest service has one slot free: one connection moves, one is
+    # cut. A service holds one of its maxconn slots for the next connection
+    # it accepts, so maxconn 2 leaves one.
+    threads, results = downloads(2)
+    reload(config(f"proxy -p{proxy}", maxconn=2))
+    for th in threads:
+        th.join(20)
+    whole = sum(1 for r in results if r.get("length") == 2000000)
+    t.eq(1, whole, "with one slot free in the new service one download goes on")
+    t.contains(server.output(), " 00027 ",
+               "the other is cut for want of a slot (27)")
+
+    # --- the service on the port is of another type now: cut (26)
+    reload(config(f"proxy -p{proxy}"))
+    threads, results = downloads(1)
+    reload(config(f"socks -p{proxy}"))
+    for th in threads:
+        th.join(20)
+    t.ok("a proxy download is cut when a socks service takes the port") \
+        if results[0].get("length", 0) < 2000000 else \
+        t.fail("a proxy download is cut when a socks service takes the port",
+               "less than 2000000 bytes", results[0].get("length"))
+    t.contains(server.output(), " 00026 ", "as its service is another one now (26)")

tests/cases/reload.py

@@ -90,6 +90,19 @@ def run(t):
     t.eq(2000000, kept.get("length"),
          "a download of a user the new configuration keeps finishes whole")
 
+    # a connection kept alive: each request is authorized by the rules in
+    # force, so alice's next request after she is removed is refused
+    keep = t.connection("127.0.0.1", origin, proxy=proxy)
+    t.eq(200, t.http(url, proxy=proxy, proxy_auth=("alice", "one"), conn=keep).status,
+         "a kept-alive connection serves alice")
+    t.write_config("reload", config(origin, first, adm, "bob:CL:two"))
+    reload_and_wait()
+    r = t.http(url, proxy=proxy, proxy_auth=("alice", "one"), conn=keep)
+    t.eq(407, r.status, "after she is removed, her next request on it is refused "
+         "with a request for credentials, authorized by the new rules")
+    t.write_config("reload", config(origin, first, adm, "alice:CL:one bob:CL:two"))
+    reload_and_wait()
+
     # alice is removed: her download is cut, being re-authenticated
     th, cut = during_reload("bob:CL:two", first)
     th.join(20)