mdw@git.distorted.org.uk Git - secnet/blob - udp.c

   1 /* UDP send/receive module for secnet */
   2
   3 /* This module enables sites to communicate by sending UDP
   4  * packets. When an instance of the module is created we can
   5  * optionally bind to a particular local IP address (not implemented
   6  * yet).
   7  *
   8  * Sites register an interest in local port numbers for receiving
   9  * packets, and can also send packets. We don't care about the source
  10  * port number for sending packets.
  11  *
  12  * Packets are offered to registered receivers in turn. Once one
  13  * accepts it, it isn't offered to any more. */
  14
  15 #include "secnet.h"
  16 #include <stdio.h>
  17 #include <unistd.h>
  18 #include <fcntl.h>
  19 #include <string.h>
  20 #include <errno.h>
  21 #include <sys/socket.h>
  22 #include "util.h"
  23
  24 static beforepoll_fn udp_beforepoll;
  25 static afterpoll_fn udp_afterpoll;
  26 static comm_request_notify_fn request_notify;
  27 static comm_release_notify_fn release_notify;
  28 static comm_sendmsg_fn udp_sendmsg;
  29
  30 /* The UDP module exports a pure closure which can be used to construct a
  31  * UDP send/receive module. Arguments:
  32  */
  33
  34 struct notify_list {
  35     comm_notify_fn *fn;
  36     void *state;
  37     struct notify_list *next;
  38 };
  39
  40 struct udp {
  41     closure_t cl;
  42     struct comm_if ops;
  43     struct cloc loc;
  44     uint16_t port;
  45     int fd;
  46     struct buffer_if *rbuf;
  47     struct notify_list *notify;
  48 };
  49
  50 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
  51                           int *timeout_io, const struct timeval *tv,
  52                           uint64_t *now)
  53 {
  54     struct udp *st=state;
  55     if (*nfds_io<1) {
  56         *nfds_io=1;
  57         return ERANGE;
  58     }
  59     *nfds_io=1;
  60     fds->fd=st->fd;
  61     fds->events=POLLIN;
  62     return 0;
  63 }
  64
  65 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds,
  66                           const struct timeval *tv, uint64_t *now)
  67 {
  68     struct udp *st=state;
  69     struct sockaddr_in from;
  70     int fromlen;
  71     struct notify_list *n;
  72     bool_t done;
  73     int rv;
  74
  75     if (nfds && (fds->revents & POLLIN)) {
  76         do {
  77             fromlen=sizeof(from);
  78             BUF_ASSERT_FREE(st->rbuf);
  79             BUF_ALLOC(st->rbuf,"udp_afterpoll");
  80             rv=recvfrom(st->fd, st->rbuf->start, st->rbuf->len, 0,
  81                         (struct sockaddr *)&from, &fromlen);
  82             if (rv>0) {
  83                 st->rbuf->size=rv;
  84                 done=False;
  85                 for (n=st->notify; n; n=n->next) {
  86                     if (n->fn(n->state, st->rbuf, &from)) {
  87                         done=True;
  88                         break;
  89                     }
  90                 }
  91                 if (!done) {
  92                     /* XXX manufacture and send NAK packet */
  93                     Message(M_WARNING,"Need to send NAK\n");
  94                     BUF_FREE(st->rbuf);
  95                 }
  96                 BUF_ASSERT_FREE(st->rbuf);
  97             } else {
  98                 BUF_FREE(st->rbuf);
  99             }
 100         } while (rv>=0);
 101     }
 102 }
 103
 104 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
 105 {
 106     struct udp *st=commst;
 107     struct notify_list *n;
 108
 109     n=safe_malloc(sizeof(*n),"request_notify");
 110     n->fn=fn;
 111     n->state=nst;
 112     n->next=st->notify;
 113     st->notify=n;
 114 }
 115
 116 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
 117 {
 118     struct udp *st=commst;
 119     struct notify_list *n, **p, *t;
 120
 121     /* XXX untested */
 122     p=&st->notify;
 123     for (n=st->notify; n; )
 124     {
 125         if (n->state==nst && n->fn==fn) {
 126             t=n;
 127             *p=n->next;
 128             n=n->next;
 129             free(t);
 130         } else {
 131             p=&n->next;
 132             n=n->next;
 133         }
 134     }
 135 }
 136
 137 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
 138                           struct sockaddr_in *dest)
 139 {
 140     struct udp *st=commst;
 141
 142     /* XXX fix error reporting */
 143     sendto(st->fd, buf->start, buf->size, 0,
 144            (struct sockaddr *)dest, sizeof(*dest));
 145
 146     return True;
 147 }
 148
 149 static void udp_phase_hook(void *sst, uint32_t new_phase)
 150 {
 151     struct udp *st=sst;
 152     struct sockaddr_in addr;
 153
 154     st->fd=socket(AF_INET, SOCK_DGRAM, 0);
 155     if (st->fd<0) {
 156         fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
 157     }
 158     if (fcntl(st->fd, F_SETFL, fcntl(st->fd, F_GETFL)|O_NONBLOCK)==-1) {
 159         fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
 160                      st->loc.file,st->loc.line);
 161     }
 162     if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
 163         fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
 164                      st->loc.file,st->loc.line);
 165     }
 166
 167     memset(&addr, 0, sizeof(addr));
 168     addr.sin_family=AF_INET;
 169     addr.sin_port=htons(st->port);
 170     if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
 171         fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
 172     }
 173
 174     register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
 175 }
 176
 177 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
 178                          list_t *args)
 179 {
 180     struct udp *st;
 181     item_t *i;
 182     dict_t *d;
 183
 184     st=safe_malloc(sizeof(*st),"udp_apply(st)");
 185     st->loc=loc;
 186     st->cl.description="udp";
 187     st->cl.type=CL_COMM;
 188     st->cl.apply=NULL;
 189     st->cl.interface=&st->ops;
 190     st->ops.st=st;
 191     st->ops.request_notify=request_notify;
 192     st->ops.release_notify=release_notify;
 193     st->ops.sendmsg=udp_sendmsg;
 194     st->port=0;
 195
 196     i=list_elem(args,0);
 197     if (!i || i->type!=t_dict) {
 198         cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
 199     }
 200     d=i->data.dict;
 201
 202     st->port=dict_read_number(d,"port",True,"udp",st->loc,0);
 203     st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
 204
 205     add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
 206
 207     return new_closure(&st->cl);
 208 }
 209
 210 init_module udp_module;
 211 void udp_module(dict_t *dict)
 212 {
 213     add_closure(dict,"udp",udp_apply);
 214 }