server: add CLIENT_FLUSHSUBS control message

This adds support to the server for a new client control message,
CLIENT_FLUSHSUBS, which flushes all subscriptions and pending retransmits
for clients belonging to a given principal.  The target principal must be
the same as the sender, unless the sender is on the opstaff ACL.

This is the server side of #103

3 files changed, 40 insertions, 1 deletions

diff --git a/server/client.c b/server/client.c
index 56c5190..02e9862 100644
--- a/server/client.c
+++ b/server/client.c
@@ -146,6 +146,24 @@ client_flush_host(struct in_addr *host)
     uloc_hflush(host);
 }
 
+/* Unlike client_flush_host, this flushes only subs, not locations */
+void
+client_flush_princ(char *target)
+{
+    int i;
+    Client *client, *next;
+    String *principal = make_string(target, 0);
+
+    for (i = 0; i < HASHSIZE; i++) {
+	for (client = client_bucket[i]; client; client = next) {
+	    next = client->next;
+	    if (client->principal == principal)
+		client_deregister(client, 0);
+	}
+    }
+    free_string(principal);
+}
+
 Code_t
 client_send_clients(void)
 {
diff --git a/server/dispatch.c b/server/dispatch.c
index 9981581..b1909e0 100644
--- a/server/dispatch.c
+++ b/server/dispatch.c
@@ -966,7 +966,7 @@ control_dispatch(ZNotice_t *notice,
 		 struct sockaddr_in *who,
 		 Server *server)
 {
-    char *opcode = notice->z_opcode;
+    char *target, *opcode = notice->z_opcode;
     Client *client;
     Code_t retval;
     int wantdefs;
@@ -1100,6 +1100,26 @@ control_dispatch(ZNotice_t *notice,
 	}
 	/* don't flush locations here, let him do it explicitly */
 	client_deregister(client, 0);
+    } else if (strcmp(opcode, CLIENT_FLUSHSUBS) == 0) {
+	target = notice->z_sender;
+	if (notice->z_message_len > 0 && *notice->z_message != 0) {
+	    target = notice->z_message;
+	    if (memchr(target, '\0', notice->z_message_len) == NULL) {
+		syslog(LOG_WARNING, "malformed flushsubs");
+		if (server == me_server)
+		    nack(notice, who);
+		return ZERR_NONE;
+	    }
+	    if (strcmp(target, notice->z_sender) != 0 &&
+		!opstaff_check(notice->z_sender)) {
+		syslog(LOG_NOTICE, "unauth flushsubs for %s by %s",
+		       target, notice->z_sender);
+		if (server == me_server)
+		    clt_ack(notice, who, AUTH_FAILED);
+		return ZERR_NONE;
+	    }
+	}
+	client_flush_princ(target);
     } else {
 	syslog(LOG_WARNING, "unknown ctl opcode %s", opcode);
 	if (server == me_server) {
diff --git a/server/zserver.h b/server/zserver.h
index 28b8fdb..f0f4fda 100644
--- a/server/zserver.h
+++ b/server/zserver.h
@@ -276,6 +276,7 @@ Code_t client_register(ZNotice_t *notice, struct in_addr *host,
 			    Client **client_p, int wantdefaults);
 void client_deregister(Client *client, int flush);
 void client_flush_host(struct in_addr *host);
+void client_flush_princ(char *target);
 void client_dump_clients(FILE *fp);
 Client *client_find(struct in_addr *host, unsigned int port);
 Code_t client_send_clients(void);