X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=udp.c;h=70928a8109fb130edd5fa53c977cc41fbeb551de;hp=65208650f998a7cbc5f670a1d7114ae40adc677b;hb=656df7e2c9b688150ebe991d79a64ac096bb5f8e;hpb=794f2398b8fe84bf398bb10d6eeca6fe6737f65f

diff --git a/udp.c b/udp.c
index 6520865..70928a8 100644
--- a/udp.c
+++ b/udp.c
@@ -5,10 +5,6 @@
  * optionally bind to a particular local IP address (not implemented
  * yet).
  *
- * Sites register an interest in local port numbers for receiving
- * packets, and can also send packets. We don't care about the source
- * port number for sending packets. 
- *
  * Packets are offered to registered receivers in turn. Once one
  * accepts it, it isn't offered to any more. */
 
@@ -20,236 +16,456 @@
 #include <errno.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 #include "util.h"
+#include "magic.h"
 #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;
 
-/* The UDP module exports a pure closure which can be used to construct a
- * UDP send/receive module. Arguments:
+struct udp {
+    struct udpcommon uc;
+    struct udpsocks socks;
+};
+
+/*
+ * 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.
  */
 
-struct notify_list {
-    comm_notify_fn *fn;
-    void *state;
-    struct notify_list *next;
-};
+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];
+    int ix=ca->ix>=0 ? ca->ix : 0;
 
-struct udp {
-    closure_t cl;
-    struct comm_if ops;
-    struct cloc loc;
-    uint16_t port;
-    int fd;
-    string_t authbind;
-    struct buffer_if *rbuf;
-    struct notify_list *notify;
-};
+    assert(ix>=0 && ix<socks->n_socks);
+    snprintf(sbuf, sizeof(sbuf), "udp:%s%s-%s",
+	     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, const struct timeval *tv,
-			  uint64_t *now)
+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 struct timeval *tv, uint64_t *now)
+const char *af_name(int af)
 {
-    struct udp *st=state;
-    struct sockaddr_in from;
-    int fromlen;
-    struct notify_list *n;
+    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,
+			  bool_t recvsend, int af,
+			  int r, int errnoval)
+{
+    bool_t success=r>=0;
+    if (us->experienced[recvsend][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",
+	      socks->desc,iaddr_to_string(&us->addr),
+	      success?"success":"trouble",
+	      recvsend?"transmitting":"receiving",
+	      af?" ":"", af?af_name(af):"");
+}
+
+static void udp_socks_afterpoll(void *state, struct pollfd *fds, int nfds)
+{
+    struct udpsocks *socks=state;
+    struct udpcommon *uc=socks->uc;
+    union iaddr from;
+    socklen_t fromlen;
     bool_t done;
     int rv;
+    int i;
+
+    struct commcommon *cc=&uc->cc;
 
-    if (nfds && (fds->revents & POLLIN)) {
+    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 {
 	    fromlen=sizeof(from);
-	    BUF_ASSERT_FREE(st->rbuf);
-	    BUF_ALLOC(st->rbuf,"udp_afterpoll");
-	    rv=recvfrom(st->fd, st->rbuf->start, st->rbuf->len, 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;
-		done=False;
-		for (n=st->notify; n; n=n->next) {
-		    if (n->fn(n->state, st->rbuf, &from)) {
-			done=True;
-			break;
+		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 (!iaddr_equal(&from,&uc->proxy,False)) {
+			Message(M_INFO,"udp: received packet that's not "
+				"from the proxy\n");
+			BUF_FREE(cc->rbuf);
+			continue;
 		    }
+		    /* 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);
 		}
-		if (!done) {
-		    uint32_t source,dest;
-		    /* XXX manufacture and send NAK packet */
-		    source=get_uint32(st->rbuf->start); /* Us */
-		    dest=get_uint32(st->rbuf->start+4); /* Them */
-		    Message(M_INFO,"udp (port %d): sending NAK\n",st->port);
-		    buffer_init(st->rbuf,0);
-		    buf_append_uint32(st->rbuf,dest);
-		    buf_append_uint32(st->rbuf,source);
-		    buf_append_uint32(st->rbuf,0); /* NAK is msg type 0 */
-		    sendto(st->fd, st->rbuf->start, st->rbuf->size, 0,
-			   (struct sockaddr *)&from, sizeof(from));
-		    BUF_FREE(st->rbuf);
+		struct comm_addr ca;
+		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 (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(cc->rbuf->start); /* Us */
+			dest=get_uint32(cc->rbuf->start+4); /* Them */
+			send_nak(&ca,source,dest,msgtype,cc->rbuf,"unwanted");
+		    }
+		    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)
+static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
+			  const struct comm_addr *dest)
 {
     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;
-}
+    struct udpcommon *uc=&st->uc;
+    struct udpsocks *socks=&st->socks;
+    uint8_t *sa;
 
-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;
+    if (uc->use_proxy) {
+	struct udpsock *us=&socks->socks[0];
+	sa=buf_prepend(buf,8);
+	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->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, 1,0, r,errno);
+	buf_unprepend(buf,8);
+    } else {
+	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, 1,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 bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
-			  struct sockaddr_in *dest)
+void udp_destroy_socket(struct udpcommon *uc, struct udpsock *us)
 {
-    struct udp *st=commst;
+    if (us->fd>=0) {
+	close(us->fd);
+	us->fd=-1;
+    }
+}
 
-    /* XXX fix error reporting */
-    sendto(st->fd, buf->start, buf->size, 0,
-	   (struct sockaddr *)dest, sizeof(*dest));
+#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;
 }
 
-static void udp_phase_hook(void *sst, uint32_t new_phase)
+bool_t udp_import_socket(struct udpcommon *uc, struct udpsock *us,
+			 int failmsgclass, int fd)
 {
-    struct udp *st=sst;
-    struct sockaddr_in addr;
+    FILLZERO(us->experienced);
+    us->fd=fd;
+    return record_socket_gotaddr(uc,us,failmsgclass);
+}
 
-    st->fd=socket(AF_INET, SOCK_DGRAM, 0);
-    if (st->fd<0) {
-	fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
-    }
-    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);
-    }
-    if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
-	fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
-		     st->loc.file,st->loc.line);
+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,)");
     }
+#endif
 
-    memset(&addr, 0, sizeof(addr));
-    addr.sin_family=AF_INET;
-    addr.sin_port=htons(st->port);
-    if (st->authbind) {
+    if (uc->authbind) {
 	pid_t c;
 	int status;
 
 	/* 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];
-	    argv[0]=st->authbind;
-	    argv[1]="00000000";
-	    argv[2]=alloca(8);
-	    if (!argv[2]) exit(ENOMEM);
-	    sprintf(argv[2],"%04X",htons(st->port));
-	    argv[3]=NULL;
-	    dup2(st->fd,0);
-	    execvp(st->authbind,argv);
-	    exit(ENOEXEC);
+	    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]=(char*)addrfam;
+	    argv[4]=NULL;
+	    dup2(us->fd,0);
+	    execvp(uc->authbind,argv);
+	    _exit(255);
 	}
-	waitpid(c,&status,0);
-	if (WEXITSTATUS(status)!=0) {
-	    errno=WEXITSTATUS(status);
-	    fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
+	while (waitpid(c,&status,0)==-1) {
+	    if (errno==EINTR) continue;
+	    FAIL("waitpid for authbind");
 	}
-    } else {
-	if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
-	    fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
+	if (status) {
+	    if (WIFEXITED(status) && WEXITSTATUS(status)<127) {
+		int es=WEXITSTATUS(status);
+		lg_perror(FAIL_LG,es,
+			  "authbind exited with error exit status %d;"
+			  " indicates error",es);
+	    } else {
+		lg_exitstatus(FAIL_LG,status,"authbind");
+	    }
+	    goto failed;
 	}
+    } else {
+	if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0)
+	    FAIL("bind (%s)",iaddr_to_string(addr));
     }
 
-    register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
+    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;
+    for (i=0; i<socks->n_socks; i++)
+	udp_make_socket(uc,&socks->socks[i],M_FATAL);
+
+    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)
 {
     struct udp *st;
-    item_t *i;
-    dict_t *d;
-
-    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->port=0;
-
-    i=list_elem(args,0);
-    if (!i || i->type!=t_dict) {
-	cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
+    list_t *caddrl;
+    list_t *l;
+    uint32_t a;
+    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;
+
+    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");
+    socks->n_socks=caddrl ? 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 (!list_length(caddrl)) {
+	    us->addr=defaultaddrs[i];
+	} else {
+	    string_item_to_iaddr(list_elem(caddrl,i),uc->port,&us->addr,"udp");
+	}
+	us->fd=-1;
+    }
+
+    l=dict_lookup(d,"proxy");
+    if (l) {
+	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(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");
+	}
+	uc->proxy.sin.sin_port=htons(item->data.number);
     }
-    d=i->data.dict;
 
-    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);
+    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);
 }
 
-init_module udp_module;
 void udp_module(dict_t *dict)
 {
     add_closure(dict,"udp",udp_apply);