[secnet] / udp.c

/* UDP send/receive module for secnet */

/* 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
 * yet).
 *
 * Packets are offered to registered receivers in turn. Once one
 * accepts it, it isn't offered to any more. */

#include "secnet.h"
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include "util.h"
#include "unaligned.h"
#include "ipaddr.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;
};

static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
			  int *timeout_io, const struct timeval *tv,
			  uint64_t *now)
{
    struct udp *st=state;
    if (*nfds_io<1) {
	*nfds_io=1;
	return ERANGE;
    }
    *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)
{
    struct udp *st=state;
    struct sockaddr_in from;
    int fromlen;
    struct notify_list *n;
    bool_t done;
    int rv;

    if (nfds && (fds->revents & POLLIN)) {
	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);
	    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) {
			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);
		    buf_unprepend(st->rbuf,2);
		    memcpy(&from.sin_port,buf_unprepend(st->rbuf,2),2);
		}
		done=False;
		for (n=st->notify; n; n=n->next) {
		    if (n->fn(n->state, st->rbuf, &from)) {
			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));
		    BUF_FREE(st->rbuf);
		}
		BUF_ASSERT_FREE(st->rbuf);
	    } else {
		BUF_FREE(st->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,
			  struct sockaddr_in *dest)
{
    struct udp *st=commst;
    uint8_t *sa;

    if (st->use_proxy) {
	sa=buf->start-8;
	memcpy(sa,&dest->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));
    } else {
	sendto(st->fd, buf->start, buf->size, 0,
	       (struct sockaddr *)dest, sizeof(*dest));
    }

    return True;
}

static void udp_phase_hook(void *sst, uint32_t new_phase)
{
    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 (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);
    }

    memset(&addr, 0, sizeof(addr));
    addr.sin_family=AF_INET;
    addr.sin_addr.s_addr=htonl(st->addr);
    addr.sin_port=htons(st->port);
    if (st->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==0) {
	    char *argv[4], addrstr[9], portstr[5];
	    sprintf(addrstr,"%08lX",(long)st->addr);
	    sprintf(portstr,"%04X",st->port);
	    argv[0]=st->authbind;
	    argv[1]=addrstr;
	    argv[2]=portstr;
	    argv[3]=NULL;
	    dup2(st->fd,0);
	    execvp(st->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);
	}
	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) {
	    fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
	}
    }

    register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
}

static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
			 list_t *args)
{
    struct udp *st;
    item_t *i,*j;
    dict_t *d;
    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.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->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");
    }
    d=i->data.dict;

    j=dict_find_item(d,"address",False,"udp",st->loc);
    st->addr=j?st->addr=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;
	memset(&st->proxy,0,sizeof(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");
	}
	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");
	}
	st->proxy.sin_port=htons(i->data.number);
	st->ops.min_start_pad=8;
    }

    add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);

    return new_closure(&st->cl);
}

void udp_module(dict_t *dict)
{
    add_closure(dict,"udp",udp_apply);
}
Commit	Line	Data
2fe58dfd SE	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	*
2fe58dfd SE	8	* Packets are offered to registered receivers in turn. Once one
	9	* accepts it, it isn't offered to any more. */
	10
8689b3a9	11	#include "secnet.h"
2fe58dfd SE	12	#include <stdio.h>
	13	#include <unistd.h>
	14	#include <fcntl.h>
	15	#include <string.h>
	16	#include <errno.h>
2fe58dfd	17	#include <sys/socket.h>
b2a56f7c	18	#include <sys/wait.h>
2fe58dfd	19	#include "util.h"
794f2398	20	#include "unaligned.h"
ff05a229	21	#include "ipaddr.h"
2fe58dfd SE	22
	23	static beforepoll_fn udp_beforepoll;
	24	static afterpoll_fn udp_afterpoll;
	25	static comm_request_notify_fn request_notify;
	26	static comm_release_notify_fn release_notify;
	27	static comm_sendmsg_fn udp_sendmsg;
	28
2fe58dfd SE	29	struct notify_list {
	30	comm_notify_fn *fn;
	31	void *state;
	32	struct notify_list *next;
	33	};
	34
	35	struct udp {
	36	closure_t cl;
	37	struct comm_if ops;
	38	struct cloc loc;
3b83c932	39	uint32_t addr;
baa06aeb	40	uint16_t port;
2fe58dfd	41	int fd;
b2a56f7c	42	string_t authbind;
2fe58dfd SE	43	struct buffer_if *rbuf;
2fe58dfd SE	44	struct notify_list *notify;
ff05a229 SE	45	bool_t use_proxy;
ff05a229 SE	46	struct sockaddr_in proxy;
2fe58dfd SE	47	};
	48
	49	static int udp_beforepoll(void state, struct pollfd fds, int *nfds_io,
	50	int timeout_io, const struct timeval tv,
	51	uint64_t *now)
	52	{
	53	struct udp *st=state;
	54	if (*nfds_io<1) {
	55	*nfds_io=1;
	56	return ERANGE;
	57	}
	58	*nfds_io=1;
	59	fds->fd=st->fd;
	60	fds->events=POLLIN;
	61	return 0;
	62	}
	63
	64	static void udp_afterpoll(void state, struct pollfd fds, int nfds,
	65	const struct timeval tv, uint64_t now)
	66	{
	67	struct udp *st=state;
	68	struct sockaddr_in from;
	69	int fromlen;
	70	struct notify_list *n;
	71	bool_t done;
	72	int rv;
	73
	74	if (nfds && (fds->revents & POLLIN)) {
	75	do {
	76	fromlen=sizeof(from);
	77	BUF_ASSERT_FREE(st->rbuf);
	78	BUF_ALLOC(st->rbuf,"udp_afterpoll");
	79	rv=recvfrom(st->fd, st->rbuf->start, st->rbuf->len, 0,
	80	(struct sockaddr *)&from, &fromlen);
	81	if (rv>0) {
	82	st->rbuf->size=rv;
ff05a229 SE	83	if (st->use_proxy) {
	84	/* Check that the packet came from our poxy server;
	85	we shouldn't be contacted directly by anybody else
	86	(since they can trivially forge source addresses) */
	87	if (memcmp(&from.sin_addr,&st->proxy.sin_addr,4)!=0 \|\|
	88	memcmp(&from.sin_port,&st->proxy.sin_port,2)!=0) {
	89	Message(M_INFO,"udp: received packet that's not "
	90	"from the proxy\n");
	91	BUF_FREE(st->rbuf);
	92	continue;
	93	}
	94	memcpy(&from.sin_addr,buf_unprepend(st->rbuf,4),4);
	95	buf_unprepend(st->rbuf,2);
	96	memcpy(&from.sin_port,buf_unprepend(st->rbuf,2),2);
	97	}
2fe58dfd SE	98	done=False;
	99	for (n=st->notify; n; n=n->next) {
	100	if (n->fn(n->state, st->rbuf, &from)) {
	101	done=True;
	102	break;
	103	}
	104	}
	105	if (!done) {
794f2398	106	uint32_t source,dest;
ff05a229	107	/* Manufacture and send NAK packet */
794f2398 SE	108	source=get_uint32(st->rbuf->start); /* Us */
	109	dest=get_uint32(st->rbuf->start+4); /* Them */
	110	Message(M_INFO,"udp (port %d): sending NAK\n",st->port);
	111	buffer_init(st->rbuf,0);
	112	buf_append_uint32(st->rbuf,dest);
	113	buf_append_uint32(st->rbuf,source);
	114	buf_append_uint32(st->rbuf,0); /* NAK is msg type 0 */
	115	sendto(st->fd, st->rbuf->start, st->rbuf->size, 0,
	116	(struct sockaddr *)&from, sizeof(from));
2fe58dfd SE	117	BUF_FREE(st->rbuf);
	118	}
	119	BUF_ASSERT_FREE(st->rbuf);
	120	} else {
	121	BUF_FREE(st->rbuf);
	122	}
	123	} while (rv>=0);
	124	}
	125	}
	126
	127	static void request_notify(void commst, void nst, comm_notify_fn *fn)
	128	{
	129	struct udp *st=commst;
	130	struct notify_list *n;
	131
	132	n=safe_malloc(sizeof(*n),"request_notify");
	133	n->fn=fn;
	134	n->state=nst;
	135	n->next=st->notify;
	136	st->notify=n;
	137	}
	138
	139	static void release_notify(void commst, void nst, comm_notify_fn *fn)
	140	{
	141	struct udp *st=commst;
	142	struct notify_list n, p, t;
	143
	144	/* XXX untested */
	145	p=&st->notify;
	146	for (n=st->notify; n; )
	147	{
	148	if (n->state==nst && n->fn==fn) {
	149	t=n;
	150	*p=n->next;
	151	n=n->next;
	152	free(t);
	153	} else {
	154	p=&n->next;
	155	n=n->next;
	156	}
	157	}
	158	}
	159
	160	static bool_t udp_sendmsg(void commst, struct buffer_if buf,
	161	struct sockaddr_in *dest)
	162	{
	163	struct udp *st=commst;
ff05a229	164	uint8_t *sa;
2fe58dfd	165
ff05a229 SE	166	if (st->use_proxy) {
	167	sa=buf->start-8;
	168	memcpy(sa,&dest->sin_addr,4);
	169	memset(sa+4,0,4);
	170	memcpy(sa+6,&dest->sin_port,2);
	171	sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy,
	172	sizeof(st->proxy));
	173	} else {
	174	sendto(st->fd, buf->start, buf->size, 0,
	175	(struct sockaddr )dest, sizeof(dest));
	176	}
2fe58dfd SE	177
	178	return True;
	179	}
	180
baa06aeb SE	181	static void udp_phase_hook(void *sst, uint32_t new_phase)
	182	{
	183	struct udp *st=sst;
	184	struct sockaddr_in addr;
	185
3b83c932	186	st->fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
baa06aeb SE	187	if (st->fd<0) {
	188	fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
	189	}
	190	if (fcntl(st->fd, F_SETFL, fcntl(st->fd, F_GETFL)\|O_NONBLOCK)==-1) {
	191	fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
	192	st->loc.file,st->loc.line);
	193	}
	194	if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
	195	fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
	196	st->loc.file,st->loc.line);
	197	}
	198
	199	memset(&addr, 0, sizeof(addr));
	200	addr.sin_family=AF_INET;
3b83c932	201	addr.sin_addr.s_addr=htonl(st->addr);
baa06aeb	202	addr.sin_port=htons(st->port);
b2a56f7c SE	203	if (st->authbind) {
	204	pid_t c;
	205	int status;
	206
	207	/* XXX this fork() and waitpid() business needs to be hidden
	208	in some system-specific library functions. */
	209	c=fork();
	210	if (c==-1) {
	211	fatal_perror("udp_phase_hook: fork() for authbind");
	212	}
	213	if (c==0) {
3b83c932 SE	214	char *argv[4], addrstr[9], portstr[5];
	215	sprintf(addrstr,"%08lX",(long)st->addr);
	216	sprintf(portstr,"%04X",st->port);
b2a56f7c	217	argv[0]=st->authbind;
3b83c932 SE	218	argv[1]=addrstr;
3b83c932 SE	219	argv[2]=portstr;
b2a56f7c SE	220	argv[3]=NULL;
	221	dup2(st->fd,0);
	222	execvp(st->authbind,argv);
3b83c932	223	_exit(255);
b2a56f7c	224	}
3b83c932 SE	225	while (waitpid(c,&status,0)==-1) {
3b83c932 SE	226	if (errno==EINTR) continue;
b2a56f7c SE	227	fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
b2a56f7c SE	228	}
3b83c932 SE	229	if (WIFSIGNALED(status)) {
	230	fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
	231	st->loc.line, WTERMSIG(status));
	232	}
	233	if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
	234	fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
	235	st->loc.line, WEXITSTATUS(status));
	236	}
b2a56f7c SE	237	} else {
	238	if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
	239	fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
	240	}
baa06aeb SE	241	}
	242
	243	register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
	244	}
	245
2fe58dfd SE	246	static list_t udp_apply(closure_t self, struct cloc loc, dict_t *context,
	247	list_t *args)
	248	{
	249	struct udp *st;
3b83c932	250	item_t i,j;
2fe58dfd	251	dict_t *d;
ff05a229 SE	252	list_t *l;
ff05a229 SE	253	uint32_t a;
2fe58dfd SE	254
	255	st=safe_malloc(sizeof(*st),"udp_apply(st)");
	256	st->loc=loc;
	257	st->cl.description="udp";
	258	st->cl.type=CL_COMM;
	259	st->cl.apply=NULL;
	260	st->cl.interface=&st->ops;
	261	st->ops.st=st;
ff05a229 SE	262	st->ops.min_start_pad=0;
ff05a229 SE	263	st->ops.min_end_pad=0;
2fe58dfd SE	264	st->ops.request_notify=request_notify;
	265	st->ops.release_notify=release_notify;
	266	st->ops.sendmsg=udp_sendmsg;
baa06aeb	267	st->port=0;
ff05a229	268	st->use_proxy=False;
2fe58dfd SE	269
	270	i=list_elem(args,0);
	271	if (!i \|\| i->type!=t_dict) {
	272	cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
	273	}
	274	d=i->data.dict;
	275
3b83c932 SE	276	j=dict_find_item(d,"address",False,"udp",st->loc);
3b83c932 SE	277	st->addr=j?st->addr=string_item_to_ipaddr(j, "udp"):INADDR_ANY;
baa06aeb	278	st->port=dict_read_number(d,"port",True,"udp",st->loc,0);
2fe58dfd	279	st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
b2a56f7c	280	st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
ff05a229 SE	281	l=dict_lookup(d,"proxy");
	282	if (l) {
	283	st->use_proxy=True;
	284	memset(&st->proxy,0,sizeof(st->proxy));
	285	st->proxy.sin_family=AF_INET;
	286	i=list_elem(l,0);
	287	if (!i \|\| i->type!=t_string) {
	288	cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
	289	}
	290	a=string_item_to_ipaddr(i,"proxy");
	291	st->proxy.sin_addr.s_addr=htonl(a);
	292	i=list_elem(l,1);
	293	if (!i \|\| i->type!=t_number) {
	294	cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
	295	}
	296	st->proxy.sin_port=htons(i->data.number);
	297	st->ops.min_start_pad=8;
	298	}
2fe58dfd	299
baa06aeb	300	add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
2fe58dfd SE	301
	302	return new_closure(&st->cl);
	303	}
	304
2fe58dfd SE	305	void udp_module(dict_t *dict)
	306	{
	307	add_closure(dict,"udp",udp_apply);
	308	}