X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=udp.c;h=b2ab85008213b06d2752667751befc3f411273a7;hp=f4206642fc15f44f1de6606bd970c6e2449797f4;hb=c6a3b1f54ccc754be82f0a2ea5b4d60746053a2b;hpb=5edf478f9f729427bb4d979d15b21db049222d68 diff --git a/udp.c b/udp.c index f420664..b2ab850 100644 --- a/udp.c +++ b/udp.c @@ -19,8 +19,10 @@ #include #include #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; @@ -38,37 +40,21 @@ struct udp { closure_t cl; struct comm_if ops; struct cloc loc; - uint32_t addr; - uint16_t port; + union iaddr addr; int fd; string_t authbind; struct buffer_if *rbuf; struct notify_list *notify; bool_t use_proxy; - struct sockaddr_in proxy; + union iaddr proxy; }; -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]; -} - static const char *addr_to_string(void *commst, const struct comm_addr *ca) { struct udp *st=commst; 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)); + iaddr_to_string(&st->addr), iaddr_to_string(&ca->ia)); return sbuf; } @@ -89,7 +75,7 @@ static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io, static void udp_afterpoll(void *state, struct pollfd *fds, int nfds) { struct udp *st=state; - struct sockaddr_in from; + union iaddr from; socklen_t fromlen; struct notify_list *n; bool_t done; @@ -101,48 +87,51 @@ static void udp_afterpoll(void *state, struct pollfd *fds, int nfds) 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(st->fd, st->rbuf->start, + buf_remaining_space(st->rbuf), + 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) { + 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 */ + FILLZERO(from); + 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; + FILLZERO(ca); + ca.comm=&st->ops; + ca.ia=from; done=False; for (n=st->notify; n; n=n->next) { - struct comm_addr ca; - FILLZERO(ca); - ca.comm=&st->ops; - ca.sin=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); @@ -193,42 +182,40 @@ static bool_t udp_sendmsg(void *commst, struct buffer_if *buf, uint8_t *sa; if (st->use_proxy) { - sa=buf->start-8; - memcpy(sa,&dest->sin.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.sin_port,2); + memcpy(sa+6,&dest->ia.sin.sin_port,2); sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy, sizeof(st->proxy)); + buf_unprepend(buf,8); } else { sendto(st->fd, buf->start, buf->size, 0, - (struct sockaddr *)&dest->sin, sizeof(dest->sin)); + &dest->ia.sa, iaddr_socklen(&dest->ia)); } return True; } -static void udp_phase_hook(void *sst, uint32_t new_phase) +static void udp_make_socket(struct udp *st, struct udp *us) { - struct udp *st=sst; - struct sockaddr_in addr; - - st->fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP); - if (st->fd<0) { + const union iaddr *addr=&us->addr; + us->fd=socket(PF_INET, 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); - FILLZERO(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; @@ -241,13 +228,20 @@ static void udp_phase_hook(void *sst, uint32_t new_phase) } if (c==0) { char *argv[4], addrstr[9], portstr[5]; - sprintf(addrstr,"%08lX",(long)st->addr); - sprintf(portstr,"%04X",st->port); + switch (addr->sa.sa_family) { + case AF_INET: + sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr); + sprintf(portstr,"%04X",addr->sin.sin_port); + break; + default: + fatal("udp (%s:%d): unsupported address family for authbind", + st->loc.file,st->loc.line); + } argv[0]=st->authbind; argv[1]=addrstr; argv[2]=portstr; argv[3]=NULL; - dup2(st->fd,0); + dup2(us->fd,0); execvp(st->authbind,argv); _exit(255); } @@ -264,11 +258,16 @@ static void udp_phase_hook(void *sst, uint32_t new_phase) 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; + udp_make_socket(st,st); register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp"); } @@ -288,13 +287,11 @@ 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->ops.addr_to_string=addr_to_string; - st->port=0; + FILLZERO(st->addr); st->use_proxy=False; i=list_elem(args,0); @@ -303,30 +300,32 @@ static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context, } d=i->data.dict; + st->addr.sa.sa_family=AF_INET; 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->addr.sin.sin_addr.s_addr=j?string_item_to_ipaddr(j, "udp"):INADDR_ANY; + st->addr.sin.sin_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; + st->proxy.sa.sa_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); + st->proxy.sin.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; + st->proxy.sin.sin_port=htons(i->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);