chiark / gitweb /
resolver: Support IPv6 name resolution
[secnet.git] / udp.c
diff --git a/udp.c b/udp.c
index add7d8d..80299ac 100644 (file)
--- a/udp.c
+++ b/udp.c
 #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"
 
 static beforepoll_fn udp_beforepoll;
 static afterpoll_fn udp_afterpoll;
@@ -32,87 +36,131 @@ struct notify_list {
     struct notify_list *next;
 };
 
+#define MAX_SOCKETS 3 /* 2 ought to do really */
+
+struct udpsock {
+    union iaddr addr;
+    int fd;
+};
+
 struct udp {
     closure_t cl;
     struct comm_if ops;
     struct cloc loc;
-    uint16_t port;
-    int fd;
+    int n_socks;
+    struct udpsock socks[MAX_SOCKETS];
     string_t authbind;
     struct buffer_if *rbuf;
     struct notify_list *notify;
     bool_t use_proxy;
-    struct sockaddr_in proxy;
+    union iaddr proxy;
 };
 
+/*
+ * 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) {
+    struct udp *st=commst;
+    static char sbuf[100];
+    int ix=ca->ix>=0 ? ca->ix : 0;
+
+    assert(ix>=0 && ix<st->n_socks);
+    snprintf(sbuf, sizeof(sbuf), "udp:%s%s-%s",
+            iaddr_to_string(&st->socks[ix].addr),
+            ca->ix<0 ? "&" : "",
+            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)
+                         int *timeout_io)
 {
+    int i;
     struct udp *st=state;
-    if (*nfds_io<1) {
-       *nfds_io=1;
+    if (*nfds_io<st->n_socks) {
+       *nfds_io=st->n_socks;
        return ERANGE;
     }
-    *nfds_io=1;
-    fds->fd=st->fd;
-    fds->events=POLLIN;
+    *nfds_io=st->n_socks;
+    for (i=0; i<st->n_socks; i++) {
+       fds[i].fd=st->socks[i].fd;
+       fds[i].events=POLLIN;
+    }
     return 0;
 }
 
-static void udp_afterpoll(void *state, struct pollfd *fds, int nfds,
-                         const struct timeval *tv, uint64_t *now)
+static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
 {
     struct udp *st=state;
-    struct sockaddr_in from;
-    int fromlen;
+    union iaddr from;
+    socklen_t fromlen;
     struct notify_list *n;
     bool_t done;
     int rv;
+    int i;
 
-    if (nfds && (fds->revents & POLLIN)) {
+    for (i=0; i<st->n_socks; i++) {
+       if (i>=nfds) continue;
+       if (!(fds[i].revents & POLLIN)) continue;
+       assert(fds[i].fd == st->socks[i].fd);
+       int fd=st->socks[i].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);
+           buffer_init(st->rbuf,calculate_max_start_pad());
+           rv=recvfrom(fd, st->rbuf->start,
+                       buf_remaining_space(st->rbuf),
+                       0, &from.sa, &fromlen);
            if (rv>0) {
                st->rbuf->size=rv;
                if (st->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,&st->proxy)) {
                        Message(M_INFO,"udp: received packet that's not "
                                "from the proxy\n");
                        BUF_FREE(st->rbuf);
                        continue;
                    }
-                   memcpy(&from.sin_addr,buf_unprepend(st->rbuf,4),4);
+                   /* proxy protocol supports ipv4 transport only */
+                   from.sa.sa_family=AF_INET;
+                   memcpy(&from.sin.sin_addr,buf_unprepend(st->rbuf,4),4);
                    buf_unprepend(st->rbuf,2);
-                   memcpy(&from.sin_port,buf_unprepend(st->rbuf,2),2);
+                   memcpy(&from.sin.sin_port,buf_unprepend(st->rbuf,2),2);
                }
+               struct comm_addr ca;
+               ca.comm=&st->ops;
+               ca.ia=from;
+               ca.ix=i;
                done=False;
                for (n=st->notify; n; n=n->next) {
-                   if (n->fn(n->state, st->rbuf, &from)) {
+                   if (n->fn(n->state, st->rbuf, &ca)) {
                        done=True;
                        break;
                    }
                }
                if (!done) {
-                   uint32_t source,dest;
-                   /* 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));
+                   uint32_t msgtype;
+                   if (st->rbuf->size>12 /* prevents traffic amplification */
+                       && ((msgtype=get_uint32(st->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");
+                   }
                    BUF_FREE(st->rbuf);
                }
                BUF_ASSERT_FREE(st->rbuf);
@@ -157,47 +205,68 @@ static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
 }
 
 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
-                         struct sockaddr_in *dest)
+                         const struct comm_addr *dest)
 {
     struct udp *st=commst;
     uint8_t *sa;
 
     if (st->use_proxy) {
-       sa=buf->start-8;
-       memcpy(sa,&dest->sin_addr,4);
+       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->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);
+       sendto(st->socks[0].fd,sa,buf->size+8,0,&st->proxy.sa,
+              iaddr_socklen(&st->proxy));
+       buf_unprepend(buf,8);
     } else {
-       sendto(st->fd, buf->start, buf->size, 0,
-              (struct sockaddr *)dest, sizeof(*dest));
+       int i,r;
+       bool_t allunsupported=True;
+       for (i=0; i<st->n_socks; i++) {
+           if (dest->ia.sa.sa_family != st->socks[i].addr.sa.sa_family)
+               /* no point even trying */
+               continue;
+           r=sendto(st->socks[i].fd, buf->start, buf->size, 0,
+                    &dest->ia.sa, iaddr_socklen(&dest->ia));
+           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)
+static void udp_make_socket(struct udp *st, struct udpsock *us)
 {
-    struct udp *st=sst;
-    struct sockaddr_in addr;
-
-    st->fd=socket(AF_INET, SOCK_DGRAM, 0);
-    if (st->fd<0) {
+    const union iaddr *addr=&us->addr;
+    us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
+    if (us->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) {
+    if (fcntl(us->fd, F_SETFL, fcntl(us->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);
+    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) fatal_perror("udp (%s:%d): setsockopt(,IPV6_V6ONLY,&1,)",
+                           st->loc.file,st->loc.line);
     }
+#endif
 
-    memset(&addr, 0, sizeof(addr));
-    addr.sin_family=AF_INET;
-    addr.sin_port=htons(st->port);
     if (st->authbind) {
        pid_t c;
        int status;
@@ -209,40 +278,78 @@ static void udp_phase_hook(void *sst, uint32_t new_phase)
            fatal_perror("udp_phase_hook: fork() for authbind");
        }
        if (c==0) {
-           char *argv[4];
+           char *argv[5], addrstr[33], portstr[5];
+           const char *addrfam;
+           int port;
+           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",
+                     st->loc.file,st->loc.line);
+           }
+           sprintf(portstr,"%04X",port);
            argv[0]=st->authbind;
-           argv[1]=strdup("00000000");
-           if (!argv[1]) exit(ENOMEM);
-           argv[2]=alloca(8);
-           if (!argv[2]) exit(ENOMEM);
-           sprintf(argv[2],"%04X",htons(st->port));
-           argv[3]=NULL;
-           dup2(st->fd,0);
+           argv[1]=addrstr;
+           argv[2]=portstr;
+           argv[3]=(char*)addrfam;
+           argv[4]=NULL;
+           dup2(us->fd,0);
            execvp(st->authbind,argv);
-           exit(ENOEXEC);
+           _exit(255);
        }
-       waitpid(c,&status,0);
-       if (WEXITSTATUS(status)!=0) {
-           errno=WEXITSTATUS(status);
+       while (waitpid(c,&status,0)==-1) {
+           if (errno==EINTR) continue;
            fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
        }
+       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));
+       }
     } else {
-       if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
+       if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0) {
            fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
        }
     }
+}
+
+static void udp_phase_hook(void *sst, uint32_t new_phase)
+{
+    struct udp *st=sst;
+    int i;
+    for (i=0; i<st->n_socks; i++)
+       udp_make_socket(st,&st->socks[i]);
 
-    register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
+    register_for_poll(st,udp_beforepoll,udp_afterpoll,MAX_SOCKETS,"udp");
 }
 
 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
                         list_t *args)
 {
     struct udp *st;
-    item_t *i;
+    item_t *item;
+    list_t *caddrl;
     dict_t *d;
     list_t *l;
     uint32_t a;
+    int i;
 
     st=safe_malloc(sizeof(*st),"udp_apply(st)");
     st->loc=loc;
@@ -251,48 +358,73 @@ static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
     st->cl.apply=NULL;
     st->cl.interface=&st->ops;
     st->ops.st=st;
-    st->ops.min_start_pad=0;
-    st->ops.min_end_pad=0;
     st->ops.request_notify=request_notify;
     st->ops.release_notify=release_notify;
     st->ops.sendmsg=udp_sendmsg;
-    st->port=0;
+    st->ops.addr_to_string=addr_to_string;
     st->use_proxy=False;
 
-    i=list_elem(args,0);
-    if (!i || i->type!=t_dict) {
+    item=list_elem(args,0);
+    if (!item || item->type!=t_dict) {
        cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
     }
-    d=i->data.dict;
+    d=item->data.dict;
+
+    int port=dict_read_number(d,"port",True,"udp",st->loc,0);
+
+    union iaddr defaultaddrs[] = {
+#ifdef CONFIG_IPV6
+       { .sin6 = { .sin6_family=AF_INET6,
+                   .sin6_port=htons(port),
+                   .sin6_addr=IN6ADDR_ANY_INIT } },
+#endif
+       { .sin = { .sin_family=AF_INET,
+                  .sin_port=htons(port),
+                  .sin_addr= { .s_addr=INADDR_ANY } } }
+    };
+
+    caddrl=dict_lookup(d,"address");
+    st->n_socks=caddrl ? list_length(caddrl) : (int)ARRAY_SIZE(defaultaddrs);
+    if (st->n_socks<=0 || st->n_socks>MAX_SOCKETS)
+       cfgfatal(st->loc,"udp","`address' must be 1..%d addresses",
+                MAX_SOCKETS);
+
+    for (i=0; i<st->n_socks; i++) {
+       struct udpsock *us=&st->socks[i];
+       if (!list_length(caddrl)) {
+           us->addr=defaultaddrs[i];
+       } else {
+           string_item_to_iaddr(list_elem(caddrl,i),port,&us->addr,"udp");
+       }
+       us->fd=-1;
+    }
 
-    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;
-       memset(&st->proxy,0,sizeof(st->proxy));
-       st->proxy.sin_family=AF_INET;
-       i=list_elem(l,0);
-       if (!i || i->type!=t_string) {
+       st->proxy.sa.sa_family=AF_INET;
+       item=list_elem(l,0);
+       if (!item || item->type!=t_string) {
            cfgfatal(st->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) {
+       a=string_item_to_ipaddr(item,"proxy");
+       st->proxy.sin.sin_addr.s_addr=htonl(a);
+       item=list_elem(l,1);
+       if (!item || item->type!=t_number) {
            cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
        }
-       st->proxy.sin_port=htons(i->data.number);
-       st->ops.min_start_pad=8;
+       st->proxy.sin.sin_port=htons(item->data.number);
     }
 
+    update_max_start_pad(&comm_max_start_pad, st->use_proxy ? 8 : 0);
+
     add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
 
     return new_closure(&st->cl);
 }
 
-init_module udp_module;
 void udp_module(dict_t *dict)
 {
     add_closure(dict,"udp",udp_apply);