X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=secnet.git;a=blobdiff_plain;f=udp.c;h=1535f290c587a9efaa261d1ad2da740283ad024e;hp=bb82026c144d0df1f56f9f52e9401dd2fae91691;hb=2d80199d7bc25b4c6e4a5ac986f8902770e82d96;hpb=4fb0f88d53fc60395a4a87b7a9ca1245ba033ee7

diff --git a/udp.c b/udp.c
index bb82026..1535f29 100644
--- a/udp.c
+++ b/udp.c
@@ -1,5 +1,24 @@
 /* UDP send/receive module for secnet */
 
+/*
+ * This file is part of secnet.
+ * See README for full list of copyright holders.
+ *
+ * secnet is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version d of the License, or
+ * (at your option) any later version.
+ * 
+ * secnet is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * version 3 along with secnet; if not, see
+ * https://www.gnu.org/licenses/gpl.html.
+ */
+
 /* This module enables sites to communicate by sending UDP
  * packets. When an instance of the module is created we can
  * optionally bind to a particular local IP address (not implemented
@@ -23,313 +42,469 @@
 #include "unaligned.h"
 #include "ipaddr.h"
 #include "magic.h"
+#include "comm-common.h"
 
-static beforepoll_fn udp_beforepoll;
-static afterpoll_fn udp_afterpoll;
-static comm_request_notify_fn request_notify;
-static comm_release_notify_fn release_notify;
 static comm_sendmsg_fn udp_sendmsg;
 
-struct notify_list {
-    comm_notify_fn *fn;
-    void *state;
-    struct notify_list *next;
-};
-
 struct udp {
-    closure_t cl;
-    struct comm_if ops;
-    struct cloc loc;
-    uint32_t addr;
-    uint16_t port;
-    int fd;
-    string_t authbind;
-    struct buffer_if *rbuf;
-    struct notify_list *notify;
-    bool_t use_proxy;
-    struct sockaddr_in proxy;
+    struct udpcommon uc;
+    struct udpsocks socks;
+    bool_t addr_configured;
+    unsigned counter;
 };
 
-static const char *saddr_to_string(const struct sockaddr_in *sin) {
-    static char bufs[2][100];
-    static int b;
-
-    b ^= 1;
-    snprintf(bufs[b], sizeof(bufs[b]), "[%s]:%d",
-	     inet_ntoa(sin->sin_addr),
-	     ntohs(sin->sin_port));
-    return bufs[b];
-}
+/*
+ * Re comm_addr.ix: This field allows us to note in the comm_addr
+ * which socket an incoming packet was received on.  This is required
+ * for conveniently logging the actual source of a packet.  But the ix
+ * does not formally form part of the address: it is not used when
+ * sending, nor when comparing two comm_addrs.
+ *
+ * The special value -1 means that the comm_addr was constructed by
+ * another module in secnet (eg the resolver), rather than being a
+ * description of the source of an incoming packet.
+ */
 
-static const char *addr_to_string(void *commst, const struct comm_addr *ca) {
+static const char *udp_addr_to_string(void *commst, const struct comm_addr *ca)
+{
     struct udp *st=commst;
+    struct udpsocks *socks=&st->socks;
     static char sbuf[100];
-
-    struct sockaddr_in la;
-    la.sin_addr.s_addr=htonl(st->addr);
-    la.sin_port=htons(st->port);
-
-    snprintf(sbuf, sizeof(sbuf), "udp:%s-%s",
-	     saddr_to_string(&la), saddr_to_string(&ca->sin));
+    int ix=ca->ix>=0 ? ca->ix : 0;
+
+    assert(ix>=0 && ix<socks->n_socks);
+    snprintf(sbuf, sizeof(sbuf), "udp#%u@l%d:%s%s-%s",
+	     st->counter, st->uc.cc.loc.line,
+	     iaddr_to_string(&socks->socks[ix].addr),
+	     ca->ix<0 && socks->n_socks>1 ? "&" : "",
+	     iaddr_to_string(&ca->ia));
     return sbuf;
 }
 
-static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
-			  int *timeout_io)
+static int udp_socks_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
+				int *timeout_io)
 {
-    struct udp *st=state;
-    if (*nfds_io<1) {
-	*nfds_io=1;
-	return ERANGE;
+    struct udpsocks *socks=state;
+    int i;
+    BEFOREPOLL_WANT_FDS(socks->n_socks);
+    for (i=0; i<socks->n_socks; i++) {
+	fds[i].fd=socks->socks[i].fd;
+	fds[i].events=POLLIN;
     }
-    *nfds_io=1;
-    fds->fd=st->fd;
-    fds->events=POLLIN;
     return 0;
 }
 
-static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
+const char *af_name(int af)
+{
+    switch (af) {
+    case AF_INET6: return "IPv6";
+    case AF_INET:  return "IPv4";
+    case 0:        return "(any)";
+    default: abort();
+    }
+}
+
+void udp_sock_experienced(struct log_if *lg, struct udpcommon *uc,
+			  struct udpsocks *socks, struct udpsock *us,
+			  const union iaddr *dest, int af,
+			  int r, int errnoval)
+{
+    bool_t success=r>=0;
+    if (us->experienced[!!dest][af][success]++)
+	return;
+    lg_perror(lg, uc->cc.cl.description, &uc->cc.loc,
+	      success ? M_INFO : M_WARNING,
+	      success ? 0 : errnoval,
+	      "%s %s experiencing some %s %s%s%s%s%s%s",
+	      socks->desc,iaddr_to_string(&us->addr),
+	      success?"success":"trouble",
+	      dest?"transmitting":"receiving",
+	      af?" ":"", af?af_name(af):"",
+	      dest?" (to ":"",
+	      dest?iaddr_to_string(dest):"",
+	      dest?")":"");
+}
+
+static void udp_socks_afterpoll(void *state, struct pollfd *fds, int nfds)
 {
-    struct udp *st=state;
-    struct sockaddr_in from;
+    struct udpsocks *socks=state;
+    struct udpcommon *uc=socks->uc;
+    union iaddr from;
     socklen_t fromlen;
-    struct notify_list *n;
     bool_t done;
     int rv;
+    int i;
 
-    if (nfds && (fds->revents & POLLIN)) {
+    struct commcommon *cc=&uc->cc;
+
+    for (i=0; i<socks->n_socks; i++) {
+	struct udpsock *us=&socks->socks[i];
+	if (i>=nfds) continue;
+	if (!(fds[i].revents & POLLIN)) continue;
+	assert(fds[i].fd == us->fd);
+	int fd=us->fd;
 	do {
-	    FILLZERO(from);
 	    fromlen=sizeof(from);
-	    BUF_ASSERT_FREE(st->rbuf);
-	    BUF_ALLOC(st->rbuf,"udp_afterpoll");
-	    buffer_init(st->rbuf,calculate_max_start_pad());
-	    rv=recvfrom(st->fd, st->rbuf->start,
-			buf_remaining_space(st->rbuf),
-			0, (struct sockaddr *)&from, &fromlen);
+	    BUF_ASSERT_FREE(cc->rbuf);
+	    BUF_ALLOC(cc->rbuf,"udp_afterpoll");
+	    buffer_init(cc->rbuf,calculate_max_start_pad());
+	    rv=recvfrom(fd, cc->rbuf->start,
+			buf_remaining_space(cc->rbuf),
+			0, &from.sa, &fromlen);
 	    if (rv>0) {
-		st->rbuf->size=rv;
-		if (st->use_proxy) {
+		cc->rbuf->size=rv;
+		if (uc->use_proxy) {
 		    /* Check that the packet came from our poxy server;
 		       we shouldn't be contacted directly by anybody else
 		       (since they can trivially forge source addresses) */
-		    if (memcmp(&from.sin_addr,&st->proxy.sin_addr,4)!=0 ||
-			memcmp(&from.sin_port,&st->proxy.sin_port,2)!=0) {
+		    if (!iaddr_equal(&from,&uc->proxy,False)) {
 			Message(M_INFO,"udp: received packet that's not "
 				"from the proxy\n");
-			BUF_FREE(st->rbuf);
+			BUF_FREE(cc->rbuf);
 			continue;
 		    }
-		    memcpy(&from.sin_addr,buf_unprepend(st->rbuf,4),4);
-		    buf_unprepend(st->rbuf,2);
-		    memcpy(&from.sin_port,buf_unprepend(st->rbuf,2),2);
+		    /* proxy protocol supports ipv4 transport only */
+		    from.sa.sa_family=AF_INET;
+		    BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_addr,4);
+		    buf_unprepend(cc->rbuf,2);
+		    BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_port,2);
 		}
 		struct comm_addr ca;
-		FILLZERO(ca);
-		ca.comm=&st->ops;
-		ca.sin=from;
-		done=False;
-		for (n=st->notify; n; n=n->next) {
-		    if (n->fn(n->state, st->rbuf, &ca)) {
-			done=True;
-			break;
-		    }
-		}
-		if (!done) {
+		ca.comm=&cc->ops;
+		ca.ia=from;
+		ca.ix=i;
+		done=comm_notify(&cc->notify, cc->rbuf, &ca);
+		if (done) {
+		    udp_sock_experienced(0,uc,socks,us,0,
+					 from.sa.sa_family,0,0);
+		} else {
 		    uint32_t msgtype;
-		    if (st->rbuf->size>12 /* prevents traffic amplification */
-			&& ((msgtype=get_uint32(st->rbuf->start+8))
+		    if (cc->rbuf->size>12 /* prevents traffic amplification */
+			&& ((msgtype=get_uint32(cc->rbuf->start+8))
 			    != LABEL_NAK)) {
 			uint32_t source,dest;
 			/* Manufacture and send NAK packet */
-			source=get_uint32(st->rbuf->start); /* Us */
-			dest=get_uint32(st->rbuf->start+4); /* Them */
-			send_nak(&ca,source,dest,msgtype,st->rbuf,"unwanted");
+			source=get_uint32(cc->rbuf->start); /* Us */
+			dest=get_uint32(cc->rbuf->start+4); /* Them */
+			send_nak(&ca,source,dest,msgtype,cc->rbuf,"unwanted");
 		    }
-		    BUF_FREE(st->rbuf);
+		    BUF_FREE(cc->rbuf);
 		}
-		BUF_ASSERT_FREE(st->rbuf);
-	    } else {
-		BUF_FREE(st->rbuf);
+		BUF_ASSERT_FREE(cc->rbuf);
+	    } else { /* rv<=0 */
+		if (errno!=EINTR && !iswouldblock(errno))
+		    udp_sock_experienced(0,uc,socks,us, 0,0, rv,errno);
+		BUF_FREE(cc->rbuf);
 	    }
 	} while (rv>=0);
     }
 }
 
-static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
-{
-    struct udp *st=commst;
-    struct notify_list *n;
-    
-    n=safe_malloc(sizeof(*n),"request_notify");
-    n->fn=fn;
-    n->state=nst;
-    n->next=st->notify;
-    st->notify=n;
-}
-
-static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
-{
-    struct udp *st=commst;
-    struct notify_list *n, **p, *t;
-
-    /* XXX untested */
-    p=&st->notify;
-    for (n=st->notify; n; )
-    {
-	if (n->state==nst && n->fn==fn) {
-	    t=n;
-	    *p=n->next;
-	    n=n->next;
-	    free(t);
-	} else {
-	    p=&n->next;
-	    n=n->next;
-	}
-    }
-}
-
 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
-			  const struct comm_addr *dest)
+			  const struct comm_addr *dest,
+			  struct comm_clientinfo *clientinfo)
 {
     struct udp *st=commst;
+    struct udpcommon *uc=&st->uc;
+    struct udpsocks *socks=&st->socks;
     uint8_t *sa;
 
-    if (st->use_proxy) {
+    if (uc->use_proxy) {
+	struct udpsock *us=&socks->socks[0];
 	sa=buf_prepend(buf,8);
-	memcpy(sa,&dest->sin.sin_addr,4);
+	if (dest->ia.sa.sa_family != AF_INET) {
+	    Message(M_INFO,
+               "udp: proxy means dropping outgoing non-IPv4 packet to %s\n",
+		    iaddr_to_string(&dest->ia));
+	    return False;
+	}
+	memcpy(sa,&dest->ia.sin.sin_addr,4);
 	memset(sa+4,0,4);
-	memcpy(sa+6,&dest->sin.sin_port,2);
-	sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy,
-	       sizeof(st->proxy));
+	memcpy(sa+6,&dest->ia.sin.sin_port,2);
+	int r=sendto(us->fd,sa,buf->size+8,0,&uc->proxy.sa,
+	       iaddr_socklen(&uc->proxy));
+	udp_sock_experienced(0,uc,socks,us, &dest->ia,0, r,errno);
 	buf_unprepend(buf,8);
     } else {
-	sendto(st->fd, buf->start, buf->size, 0,
-	       (struct sockaddr *)&dest->sin, sizeof(dest->sin));
+	int i,r;
+	bool_t allunsupported=True;
+	int af=dest->ia.sa.sa_family;
+	for (i=0; i<socks->n_socks; i++) {
+	    struct udpsock *us=&socks->socks[i];
+	    if (us->addr.sa.sa_family != af)
+		/* no point even trying */
+		continue;
+	    r=sendto(us->fd, buf->start, buf->size, 0,
+		     &dest->ia.sa, iaddr_socklen(&dest->ia));
+	    udp_sock_experienced(0,uc,socks,us, &dest->ia,af, r,errno);
+	    if (r>=0) return True;
+	    if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH))
+		/* who knows what that error means? */
+		allunsupported=False;
+	}
+	return !allunsupported; /* see doc for comm_sendmsg_fn in secnet.h */
     }
 
     return True;
 }
 
-static void udp_phase_hook(void *sst, uint32_t new_phase)
+void udp_destroy_socket(struct udpcommon *uc, struct udpsock *us)
 {
-    struct udp *st=sst;
-    struct sockaddr_in addr;
-
-    st->fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
-    if (st->fd<0) {
-	fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
+    if (us->fd>=0) {
+	close(us->fd);
+	us->fd=-1;
     }
-    if (fcntl(st->fd, F_SETFL, fcntl(st->fd, F_GETFL)|O_NONBLOCK)==-1) {
-	fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
-		     st->loc.file,st->loc.line);
+}
+
+#define FAIL_LG 0, cc->cl.description, &cc->loc, failmsgclass
+#define FAIL(...) do{						\
+        lg_perror(FAIL_LG,errno,__VA_ARGS__);	\
+	goto failed;						\
+    }while(0)
+
+static bool_t record_socket_gotaddr(struct udpcommon *uc, struct udpsock *us,
+				    int failmsgclass)
+{
+    struct commcommon *cc=&uc->cc;
+    socklen_t salen=sizeof(us->addr);
+    int r=getsockname(us->fd,&us->addr.sa,&salen);
+    if (r) FAIL("getsockname()");
+    if (salen>sizeof(us->addr)) { errno=0; FAIL("getsockname() length"); }
+    return True;
+
+ failed:
+    return False;
+}
+
+bool_t udp_import_socket(struct udpcommon *uc, struct udpsock *us,
+			 int failmsgclass, int fd)
+{
+    FILLZERO(us->experienced);
+    us->fd=fd;
+    return record_socket_gotaddr(uc,us,failmsgclass);
+}
+
+bool_t udp_make_socket(struct udpcommon *uc, struct udpsock *us,
+		       int failmsgclass)
+{
+    const union iaddr *addr=&us->addr;
+    struct commcommon *cc=&uc->cc;
+    us->fd=-1;
+
+    FILLZERO(us->experienced);
+    us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
+    if (us->fd<0) FAIL("socket");
+    setnonblock(us->fd);
+    setcloexec(us->fd);
+#ifdef CONFIG_IPV6
+    if (addr->sa.sa_family==AF_INET6) {
+	int r;
+	int optval=1;
+	socklen_t optlen=sizeof(optval);
+	r=setsockopt(us->fd,IPPROTO_IPV6,IPV6_V6ONLY,&optval,optlen);
+	if (r) FAIL("setsockopt(,IPV6_V6ONLY,&1,)");
     }
-    setcloexec(st->fd);
+#endif
 
-    FILLZERO(addr);
-    addr.sin_family=AF_INET;
-    addr.sin_addr.s_addr=htonl(st->addr);
-    addr.sin_port=htons(st->port);
-    if (st->authbind) {
+    if (uc->authbind) {
 	pid_t c;
 	int status;
+	char desc[200];
+	snprintf(desc,sizeof(desc),"authbind for %s: %s",
+		 iaddr_to_string(addr), uc->authbind);
 
 	/* XXX this fork() and waitpid() business needs to be hidden
 	   in some system-specific library functions. */
 	c=fork();
-	if (c==-1) {
-	    fatal_perror("udp_phase_hook: fork() for authbind");
-	}
+	if (c==-1)
+	    FAIL("fork() for authbind");
 	if (c==0) {
-	    char *argv[4], addrstr[9], portstr[5];
-	    sprintf(addrstr,"%08lX",(long)addr.sin_addr.s_addr);
-	    sprintf(portstr,"%04X",addr.sin_port);
-	    argv[0]=st->authbind;
+	    char *argv[5], addrstr[33], portstr[5];
+	    const char *addrfam;
+	    int port;
+	    afterfork();
+	    switch (addr->sa.sa_family) {
+	    case AF_INET:
+		sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr);
+		port=addr->sin.sin_port;
+		addrfam=NULL;
+		break;
+#ifdef CONFIG_IPV6
+	    case AF_INET6: {
+		int i;
+		for (i=0; i<16; i++)
+		    sprintf(addrstr+i*2,"%02X",addr->sin6.sin6_addr.s6_addr[i]);
+		port=addr->sin6.sin6_port;
+		addrfam="6";
+		break;
+	    }
+#endif /*CONFIG_IPV6*/
+	    default:
+		fatal("udp (%s:%d): unsupported address family for authbind",
+		      cc->loc.file,cc->loc.line);
+	    }
+	    sprintf(portstr,"%04X",port);
+	    argv[0]=uc->authbind;
 	    argv[1]=addrstr;
 	    argv[2]=portstr;
-	    argv[3]=NULL;
-	    dup2(st->fd,0);
-	    execvp(st->authbind,argv);
+	    argv[3]=(char*)addrfam;
+	    argv[4]=NULL;
+	    dup2(us->fd,0);
+	    execvp(uc->authbind,argv);
 	    _exit(255);
 	}
 	while (waitpid(c,&status,0)==-1) {
 	    if (errno==EINTR) continue;
-	    fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
+	    FAIL("waitpid for authbind");
 	}
-	if (WIFSIGNALED(status)) {
-	    fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
-		  st->loc.line, WTERMSIG(status));
-	}
-	if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
-	    fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
-		  st->loc.line, WEXITSTATUS(status));
+	if (status) {
+	    if (WIFEXITED(status) && WEXITSTATUS(status)<127) {
+		int es=WEXITSTATUS(status);
+		lg_perror(FAIL_LG,es,
+			  "%s exited with error exit status %d;"
+			  " indicates error",desc,es);
+	    } else {
+		lg_exitstatus(FAIL_LG,status,desc);
+	    }
+	    goto failed;
 	}
     } else {
-	if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
-	    fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
-	}
+	if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0)
+	    FAIL("bind (%s)",iaddr_to_string(addr));
+    }
+
+    bool_t ok=record_socket_gotaddr(uc,us,failmsgclass);
+    if (!ok) goto failed;
+
+    return True;
+
+failed:
+    udp_destroy_socket(uc,us);
+    return False;
+}
+
+#undef FAIL
+
+void udp_socks_register(struct udpcommon *uc, struct udpsocks *socks,
+			const char *desc)
+{
+    socks->uc=uc;
+    socks->desc=desc;
+    socks->interest=
+	register_for_poll(socks,udp_socks_beforepoll,udp_socks_afterpoll,"udp");
+}
+
+void udp_socks_deregister(struct udpcommon *uc, struct udpsocks *socks)
+{
+    socks->uc=uc;
+    deregister_for_poll(socks->interest);
+}
+
+void udp_socks_childpersist(struct udpcommon *uc, struct udpsocks *socks)
+{
+    int i;
+    for (i=0; i<socks->n_socks; i++)
+	udp_destroy_socket(uc,&socks->socks[i]);
+}
+
+static void udp_childpersist_hook(void *sst, uint32_t new_phase)
+{
+    struct udp *st=sst;
+    udp_socks_childpersist(&st->uc,&st->socks);
+}
+
+static void udp_phase_hook(void *sst, uint32_t new_phase)
+{
+    struct udp *st=sst;
+    struct udpsocks *socks=&st->socks;
+    struct udpcommon *uc=&st->uc;
+    int i;
+    bool_t anydone=0;
+
+    for (i=0; i<socks->n_socks; i++) {
+	bool_t required=st->addr_configured
+	    || (!anydone && i==socks->n_socks-1);
+	anydone += udp_make_socket(uc,&socks->socks[i],
+				   required ? M_FATAL : M_WARNING);
     }
 
-    register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
+    udp_socks_register(uc,socks, uc->use_proxy ? "proxy" : "socket");
+
+    add_hook(PHASE_CHILDPERSIST,udp_childpersist_hook,st);
 }
 
 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
 			 list_t *args)
 {
+    static unsigned counter;
+
     struct udp *st;
-    item_t *i,*j;
-    dict_t *d;
+    list_t *caddrl;
     list_t *l;
     uint32_t a;
-
-    st=safe_malloc(sizeof(*st),"udp_apply(st)");
-    st->loc=loc;
-    st->cl.description="udp";
-    st->cl.type=CL_COMM;
-    st->cl.apply=NULL;
-    st->cl.interface=&st->ops;
-    st->ops.st=st;
-    st->ops.request_notify=request_notify;
-    st->ops.release_notify=release_notify;
-    st->ops.sendmsg=udp_sendmsg;
-    st->ops.addr_to_string=addr_to_string;
-    st->port=0;
-    st->use_proxy=False;
-
-    i=list_elem(args,0);
-    if (!i || i->type!=t_dict) {
-	cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
+    int i;
+
+    COMM_APPLY(st,&st->uc.cc,udp_,"udp",loc);
+    COMM_APPLY_STANDARD(st,&st->uc.cc,"udp",args);
+    UDP_APPLY_STANDARD(st,&st->uc,"udp");
+
+    struct udpcommon *uc=&st->uc;
+    struct udpsocks *socks=&st->socks;
+    struct commcommon *cc=&uc->cc;
+
+    st->counter=counter++;
+
+    union iaddr defaultaddrs[] = {
+#ifdef CONFIG_IPV6
+	{ .sin6 = { .sin6_family=AF_INET6,
+		    .sin6_port=htons(uc->port),
+		    .sin6_addr=IN6ADDR_ANY_INIT } },
+#endif
+	{ .sin = { .sin_family=AF_INET,
+		   .sin_port=htons(uc->port),
+		   .sin_addr= { .s_addr=INADDR_ANY } } }
+    };
+
+    caddrl=dict_lookup(d,"address");
+    st->addr_configured=!!caddrl;
+    socks->n_socks=st->addr_configured ? list_length(caddrl)
+	: (int)ARRAY_SIZE(defaultaddrs);
+    if (socks->n_socks<=0 || socks->n_socks>UDP_MAX_SOCKETS)
+	cfgfatal(cc->loc,"udp","`address' must be 1..%d addresses",
+		 UDP_MAX_SOCKETS);
+
+    for (i=0; i<socks->n_socks; i++) {
+	struct udpsock *us=&socks->socks[i];
+	if (!st->addr_configured) {
+	    us->addr=defaultaddrs[i];
+	} else {
+	    string_item_to_iaddr(list_elem(caddrl,i),uc->port,&us->addr,"udp");
+	}
+	us->fd=-1;
     }
-    d=i->data.dict;
 
-    j=dict_find_item(d,"address",False,"udp",st->loc);
-    st->addr=j?string_item_to_ipaddr(j, "udp"):INADDR_ANY;
-    st->port=dict_read_number(d,"port",True,"udp",st->loc,0);
-    st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
-    st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
     l=dict_lookup(d,"proxy");
     if (l) {
-	st->use_proxy=True;
-	FILLZERO(st->proxy);
-	st->proxy.sin_family=AF_INET;
-	i=list_elem(l,0);
-	if (!i || i->type!=t_string) {
-	    cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
+	uc->use_proxy=True;
+	uc->proxy.sa.sa_family=AF_INET;
+	item=list_elem(l,0);
+	if (!item || item->type!=t_string) {
+	    cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n");
 	}
-	a=string_item_to_ipaddr(i,"proxy");
-	st->proxy.sin_addr.s_addr=htonl(a);
-	i=list_elem(l,1);
-	if (!i || i->type!=t_number) {
-	    cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
+	a=string_item_to_ipaddr(item,"proxy");
+	uc->proxy.sin.sin_addr.s_addr=htonl(a);
+	item=list_elem(l,1);
+	if (!item || item->type!=t_number) {
+	    cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n");
 	}
-	st->proxy.sin_port=htons(i->data.number);
+	uc->proxy.sin.sin_port=htons(item->data.number);
     }
 
-    update_max_start_pad(&comm_max_start_pad, st->use_proxy ? 8 : 0);
+    update_max_start_pad(&comm_max_start_pad, uc->use_proxy ? 8 : 0);
 
     add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
 
-    return new_closure(&st->cl);
+    return new_closure(&cc->cl);
 }
 
 void udp_module(dict_t *dict)