/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */ /* lib/krb5/os/sendto_kdc.c */ /* * Copyright 1990,1991,2001,2002,2004,2005,2007,2008 by the Massachusetts Institute of Technology. * All Rights Reserved. * * Export of this software from the United States of America may * require a specific license from the United States Government. * It is the responsibility of any person or organization contemplating * export to obtain such a license before exporting. * * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and * distribute this software and its documentation for any purpose and * without fee is hereby granted, provided that the above copyright * notice appear in all copies and that both that copyright notice and * this permission notice appear in supporting documentation, and that * the name of M.I.T. not be used in advertising or publicity pertaining * to distribution of the software without specific, written prior * permission. Furthermore if you modify this software you must label * your software as modified software and not distribute it in such a * fashion that it might be confused with the original M.I.T. software. * M.I.T. makes no representations about the suitability of * this software for any purpose. It is provided "as is" without express * or implied warranty. */ /* Send packet to KDC for realm; wait for response, retransmitting * as necessary. */ #include "fake-addrinfo.h" #include "k5-int.h" #include "os-proto.h" #ifdef _WIN32 #include #endif #if defined(HAVE_POLL_H) #include #define USE_POLL #define MAX_POLLFDS 1024 #elif defined(HAVE_SYS_SELECT_H) #include #endif #ifndef _WIN32 /* For FIONBIO. */ #include #ifdef HAVE_SYS_FILIO_H #include #endif #endif #define MAX_PASS 3 #define DEFAULT_UDP_PREF_LIMIT 1465 #define HARD_UDP_LIMIT 32700 /* could probably do 64K-epsilon ? */ #undef DEBUG #ifdef DEBUG int krb5int_debug_sendto_kdc = 0; #define debug krb5int_debug_sendto_kdc static void default_debug_handler (const void *data, size_t len) { #if 0 static FILE *logfile; if (logfile == NULL) { logfile = fopen("/tmp/sendto_kdc.log", "a"); if (logfile == NULL) return; setbuf(logfile, NULL); } fwrite(data, 1, len, logfile); #else fwrite(data, 1, len, stderr); /* stderr is unbuffered */ #endif } void (*krb5int_sendtokdc_debug_handler) (const void *, size_t) = default_debug_handler; static void put(const void *ptr, size_t len) { (*krb5int_sendtokdc_debug_handler)(ptr, len); } static void putstr(const char *str) { put(str, strlen(str)); } #else void (*krb5int_sendtokdc_debug_handler) (const void *, size_t) = 0; #endif #define dprint krb5int_debug_fprint void krb5int_debug_fprint (const char *fmt, ...) { #ifdef DEBUG va_list args; /* Temporaries for variable arguments, etc. */ krb5_error_code kerr; int err; fd_set *rfds, *wfds, *xfds; int i; int maxfd; struct timeval *tv; struct addrinfo *ai; const krb5_data *d; char addrbuf[NI_MAXHOST], portbuf[NI_MAXSERV]; const char *p; #ifndef max #define max(a,b) ((a) > (b) ? (a) : (b)) #endif char tmpbuf[max(NI_MAXHOST + NI_MAXSERV + 30, 200)]; struct k5buf buf; if (!krb5int_debug_sendto_kdc) return; va_start(args, fmt); #define putf(FMT,X) (snprintf(tmpbuf,sizeof(tmpbuf),FMT,X),putstr(tmpbuf)) for (; *fmt; fmt++) { if (*fmt != '%') { const char *fmt2; size_t len; for (fmt2 = fmt+1; *fmt2; fmt2++) if (*fmt2 == '%') break; len = fmt2 - fmt; put(fmt, len); fmt += len - 1; /* then fmt++ in loop header */ continue; } /* After this, always processing a '%' sequence. */ fmt++; switch (*fmt) { case 0: default: abort(); case 'E': /* %E => krb5_error_code */ kerr = va_arg(args, krb5_error_code); snprintf(tmpbuf, sizeof(tmpbuf), "%lu/", (unsigned long) kerr); putstr(tmpbuf); p = error_message(kerr); putstr(p); break; case 'm': /* %m => errno value (int) */ /* Like syslog's %m except the errno value is passed in rather than the current value. */ err = va_arg(args, int); putf("%d/", err); p = NULL; #ifdef HAVE_STRERROR_R if (strerror_r(err, tmpbuf, sizeof(tmpbuf)) == 0) p = tmpbuf; #endif if (p == NULL) p = strerror(err); putstr(p); break; case 's': /* %s => char * */ p = va_arg(args, const char *); putstr(p); break; case 't': /* %t => struct timeval * */ tv = va_arg(args, struct timeval *); if (tv) { snprintf(tmpbuf, sizeof(tmpbuf), "%ld.%06ld", (long) tv->tv_sec, (long) tv->tv_usec); putstr(tmpbuf); } else putstr("never"); break; case 'd': /* %d => int */ putf("%d", va_arg(args, int)); break; case 'p': /* %p => pointer */ putf("%p", va_arg(args, void*)); break; case 'A': /* %A => addrinfo */ ai = va_arg(args, struct addrinfo *); krb5int_buf_init_dynamic(&buf); if (ai->ai_socktype == SOCK_DGRAM) krb5int_buf_add(&buf, "dgram"); else if (ai->ai_socktype == SOCK_STREAM) krb5int_buf_add(&buf, "stream"); else krb5int_buf_add_fmt(&buf, "socktype%d", ai->ai_socktype); if (0 != getnameinfo (ai->ai_addr, ai->ai_addrlen, addrbuf, sizeof (addrbuf), portbuf, sizeof (portbuf), NI_NUMERICHOST | NI_NUMERICSERV)) { if (ai->ai_addr->sa_family == AF_UNSPEC) krb5int_buf_add(&buf, " AF_UNSPEC"); else krb5int_buf_add_fmt(&buf, " af%d", ai->ai_addr->sa_family); } else krb5int_buf_add_fmt(&buf, " %s.%s", addrbuf, portbuf); if (krb5int_buf_data(&buf)) putstr(krb5int_buf_data(&buf)); krb5int_free_buf(&buf); break; case 'D': /* %D => krb5_data * */ d = va_arg(args, krb5_data *); /* may not be nul-terminated */ put(d->data, d->length); break; } } va_end(args); #endif } static int in_addrlist(struct server_entry *entry, struct serverlist *list) { size_t i; struct server_entry *le; for (i = 0; i < list->nservers; i++) { le = &list->servers[i]; if (entry->hostname != NULL && le->hostname != NULL && strcmp(entry->hostname, le->hostname) == 0) return 1; if (entry->hostname == NULL && le->hostname == NULL && entry->addrlen == le->addrlen && memcmp(&entry->addr, &le->addr, entry->addrlen) == 0) return 1; } return 0; } static int check_for_svc_unavailable (krb5_context context, const krb5_data *reply, void *msg_handler_data) { krb5_error_code *retval = (krb5_error_code *)msg_handler_data; *retval = 0; if (krb5_is_krb_error(reply)) { krb5_error *err_reply; if (decode_krb5_error(reply, &err_reply) == 0) { *retval = err_reply->error; krb5_free_error(context, err_reply); /* Returning 0 means continue to next KDC */ return (*retval != KDC_ERR_SVC_UNAVAILABLE); } } return 1; } /* * send the formatted request 'message' to a KDC for realm 'realm' and * return the response (if any) in 'reply'. * * If the message is sent and a response is received, 0 is returned, * otherwise an error code is returned. * * The storage for 'reply' is allocated and should be freed by the caller * when finished. */ krb5_error_code krb5_sendto_kdc(krb5_context context, const krb5_data *message, const krb5_data *realm, krb5_data *reply, int *use_master, int tcp_only) { krb5_error_code retval, err; struct serverlist servers; int socktype1 = 0, socktype2 = 0, server_used; /* * find KDC location(s) for realm */ /* * BUG: This code won't return "interesting" errors (e.g., out of mem, * bad config file) from locate_kdc. KRB5_REALM_CANT_RESOLVE can be * ignored from one query of two, but if only one query is done, or * both return that error, it should be returned to the caller. Also, * "interesting" errors (not KRB5_KDC_UNREACH) from sendto_{udp,tcp} * should probably be returned as well. */ dprint("krb5_sendto_kdc(%d@%p, \"%D\", use_master=%d, tcp_only=%d)\n", message->length, message->data, realm, *use_master, tcp_only); TRACE_SENDTO_KDC(context, message->length, realm, *use_master, tcp_only); if (!tcp_only && context->udp_pref_limit < 0) { int tmp; retval = profile_get_integer(context->profile, KRB5_CONF_LIBDEFAULTS, KRB5_CONF_UDP_PREFERENCE_LIMIT, 0, DEFAULT_UDP_PREF_LIMIT, &tmp); if (retval) return retval; if (tmp < 0) tmp = DEFAULT_UDP_PREF_LIMIT; else if (tmp > HARD_UDP_LIMIT) /* In the unlikely case that a *really* big value is given, let 'em use as big as we think we can support. */ tmp = HARD_UDP_LIMIT; context->udp_pref_limit = tmp; } if (tcp_only) socktype1 = SOCK_STREAM, socktype2 = 0; else if (message->length <= (unsigned int) context->udp_pref_limit) socktype1 = SOCK_DGRAM, socktype2 = SOCK_STREAM; else socktype1 = SOCK_STREAM, socktype2 = SOCK_DGRAM; retval = k5_locate_kdc(context, realm, &servers, *use_master, tcp_only ? SOCK_STREAM : 0); if (retval) return retval; retval = k5_sendto(context, message, &servers, socktype1, socktype2, NULL, reply, NULL, NULL, &server_used, check_for_svc_unavailable, &err); if (retval == KRB5_KDC_UNREACH) { if (err == KDC_ERR_SVC_UNAVAILABLE) { retval = KRB5KDC_ERR_SVC_UNAVAILABLE; } else { krb5_set_error_message(context, retval, _("Cannot contact any KDC for realm " "'%.*s'"), realm->length, realm->data); } } if (retval) goto cleanup; /* Set use_master to 1 if we ended up talking to a master when we didn't * explicitly request to. */ if (*use_master == 0) { struct serverlist mservers; struct server_entry *entry = &servers.servers[server_used]; retval = k5_locate_kdc(context, realm, &mservers, TRUE, entry->socktype); if (retval == 0) { if (in_addrlist(entry, &mservers)) *use_master = 1; k5_free_serverlist(&mservers); } TRACE_SENDTO_KDC_MASTER(context, *use_master); retval = 0; } cleanup: k5_free_serverlist(&servers); return retval; } #ifdef DEBUG #ifdef _WIN32 #define dperror(MSG) \ dprint("%s: an error occurred ... " \ "\tline=%d errno=%m socketerrno=%m\n", \ (MSG), __LINE__, errno, SOCKET_ERRNO) #else #define dperror(MSG) dprint("%s: %m\n", MSG, errno) #endif #define dfprintf(ARGLIST) (debug ? fprintf ARGLIST : 0) #else /* ! DEBUG */ #define dperror(MSG) ((void)(MSG)) #define dfprintf(ARGLIST) ((void)0) #endif /* * Notes: * * Getting "connection refused" on a connected UDP socket causes * select to indicate write capability on UNIX, but only shows up * as an exception on Windows. (I don't think any UNIX system flags * the error as an exception.) So we check for both, or make it * system-specific. * * Always watch for responses from *any* of the servers. Eventually * fix the UDP code to do the same. * * To do: * - TCP NOPUSH/CORK socket options? * - error codes that don't suck * - getsockopt(SO_ERROR) to check connect status * - handle error RESPONSE_TOO_BIG from UDP server and use TCP * connections already in progress */ #include "cm.h" /* * Currently only sendto_kdc.c knows how to use poll(); the other candidate * user, lib/apputils/net-server.c, is stuck using select() for the moment * since it is entangled with the RPC library. The following cm_* functions * are not fully generic, are O(n^2) in the poll case, and are limited to * handling 1024 connections (in order to maintain a constant-sized selstate). * More rearchitecting would be appropriate before extending this support to * the KDC and kadmind. */ static void cm_init_selstate(struct select_state *selstate) { selstate->nfds = 0; selstate->end_time.tv_sec = selstate->end_time.tv_usec = 0; #ifndef USE_POLL selstate->max = 0; FD_ZERO(&selstate->rfds); FD_ZERO(&selstate->wfds); FD_ZERO(&selstate->xfds); #endif } static krb5_boolean cm_add_fd(struct select_state *selstate, int fd, unsigned int ssflags) { #ifdef USE_POLL if (selstate->nfds >= MAX_POLLFDS) return FALSE; selstate->fds[selstate->nfds].fd = fd; selstate->fds[selstate->nfds].events = 0; if (ssflags & SSF_READ) selstate->fds[selstate->nfds].events |= POLLIN; if (ssflags & SSF_WRITE) selstate->fds[selstate->nfds].events |= POLLOUT; #else #ifndef _WIN32 /* On Windows FD_SETSIZE is a count, not a max value. */ if (fd >= FD_SETSIZE) return FALSE; #endif if (ssflags & SSF_READ) FD_SET(fd, &selstate->rfds); if (ssflags & SSF_WRITE) FD_SET(fd, &selstate->wfds); if (ssflags & SSF_EXCEPTION) FD_SET(fd, &selstate->xfds); if (selstate->max <= fd) selstate->max = fd + 1; #endif selstate->nfds++; return TRUE; } static void cm_remove_fd(struct select_state *selstate, int fd) { #ifdef USE_POLL int i; /* Find the FD in the array and move the last entry to its place. */ assert(selstate->nfds > 0); for (i = 0; i < selstate->nfds && selstate->fds[i].fd != fd; i++); assert(i < selstate->nfds); selstate->fds[i] = selstate->fds[selstate->nfds - 1]; #else FD_CLR(fd, &selstate->rfds); FD_CLR(fd, &selstate->wfds); FD_CLR(fd, &selstate->xfds); if (selstate->max == 1 + fd) { while (selstate->max > 0 && ! FD_ISSET(selstate->max-1, &selstate->rfds) && ! FD_ISSET(selstate->max-1, &selstate->wfds) && ! FD_ISSET(selstate->max-1, &selstate->xfds)) selstate->max--; dprint("new max_fd + 1 is %d\n", selstate->max); } #endif selstate->nfds--; } static void cm_unset_write(struct select_state *selstate, int fd) { #ifdef USE_POLL int i; for (i = 0; i < selstate->nfds && selstate->fds[i].fd != fd; i++); assert(i < selstate->nfds); selstate->fds[i].events &= ~POLLOUT; #else FD_CLR(fd, &selstate->wfds); #endif } static krb5_error_code cm_select_or_poll(const struct select_state *in, struct select_state *out, int *sret) { #ifdef USE_POLL struct timeval now; int e, timeout; if (in->end_time.tv_sec == 0) timeout = -1; else { e = k5_getcurtime(&now); if (e) return e; timeout = (in->end_time.tv_sec - now.tv_sec) * 1000 + (in->end_time.tv_usec - now.tv_usec) / 1000; } /* We don't need a separate copy of the selstate for poll, but use one * anyone for consistency with the select wrapper. */ *out = *in; *sret = poll(out->fds, out->nfds, timeout); e = SOCKET_ERRNO; return (*sret < 0) ? e : 0; #else /* Use the select wrapper from cm.c. */ return krb5int_cm_call_select(in, out, sret); #endif } static unsigned int cm_get_ssflags(struct select_state *selstate, int fd) { unsigned int ssflags = 0; #ifdef USE_POLL int i; for (i = 0; i < selstate->nfds && selstate->fds[i].fd != fd; i++); assert(i < selstate->nfds); if (selstate->fds[i].revents & POLLIN) ssflags |= SSF_READ; if (selstate->fds[i].revents & POLLOUT) ssflags |= SSF_WRITE; if (selstate->fds[i].revents & POLLERR) ssflags |= SSF_EXCEPTION; #else if (FD_ISSET(fd, &selstate->rfds)) ssflags |= SSF_READ; if (FD_ISSET(fd, &selstate->wfds)) ssflags |= SSF_WRITE; if (FD_ISSET(fd, &selstate->xfds)) ssflags |= SSF_EXCEPTION; #endif return ssflags; } static int service_tcp_fd(krb5_context context, struct conn_state *conn, struct select_state *selstate, int ssflags); static int service_udp_fd(krb5_context context, struct conn_state *conn, struct select_state *selstate, int ssflags); static void set_conn_state_msg_length (struct conn_state *state, const krb5_data *message) { if (!message || message->length == 0) return; if (!state->is_udp) { store_32_be(message->length, state->x.out.msg_len_buf); SG_SET(&state->x.out.sgbuf[0], state->x.out.msg_len_buf, 4); SG_SET(&state->x.out.sgbuf[1], message->data, message->length); state->x.out.sg_count = 2; } else { SG_SET(&state->x.out.sgbuf[0], message->data, message->length); SG_SET(&state->x.out.sgbuf[1], 0, 0); state->x.out.sg_count = 1; } } static krb5_error_code add_connection(struct conn_state **conns, struct addrinfo *ai, size_t server_index, const krb5_data *message, char **udpbufp) { struct conn_state *state, **tailptr; state = calloc(1, sizeof(*state)); if (state == NULL) return ENOMEM; state->state = INITIALIZING; state->err = 0; state->x.out.sgp = state->x.out.sgbuf; state->socktype = ai->ai_socktype; state->family = ai->ai_family; state->addrlen = ai->ai_addrlen; memcpy(&state->addr, ai->ai_addr, ai->ai_addrlen); state->fd = INVALID_SOCKET; state->server_index = server_index; SG_SET(&state->x.out.sgbuf[1], 0, 0); if (ai->ai_socktype == SOCK_STREAM) { /* SG_SET(&state->x.out.sgbuf[0], message_len_buf, 4); SG_SET(&state->x.out.sgbuf[1], message->data, message->length); state->x.out.sg_count = 2; */ state->is_udp = 0; state->service = service_tcp_fd; set_conn_state_msg_length (state, message); } else { /* SG_SET(&state->x.out.sgbuf[0], message->data, message->length); SG_SET(&state->x.out.sgbuf[1], 0, 0); state->x.out.sg_count = 1; */ state->is_udp = 1; state->service = service_udp_fd; set_conn_state_msg_length (state, message); if (*udpbufp == NULL) { *udpbufp = malloc(krb5_max_dgram_size); if (*udpbufp == 0) return ENOMEM; } state->x.in.buf = *udpbufp; state->x.in.bufsize = krb5_max_dgram_size; } /* Chain the new state onto the tail of the list. */ for (tailptr = conns; *tailptr != NULL; tailptr = &(*tailptr)->next); *tailptr = state; return 0; } static int translate_ai_error (int err) { switch (err) { case 0: return 0; case EAI_BADFLAGS: case EAI_FAMILY: case EAI_SOCKTYPE: case EAI_SERVICE: /* All of these indicate bad inputs to getaddrinfo. */ return EINVAL; case EAI_AGAIN: /* Translate to standard errno code. */ return EAGAIN; case EAI_MEMORY: /* Translate to standard errno code. */ return ENOMEM; #ifdef EAI_ADDRFAMILY case EAI_ADDRFAMILY: #endif #if defined(EAI_NODATA) && EAI_NODATA != EAI_NONAME case EAI_NODATA: #endif case EAI_NONAME: /* Name not known or no address data, but no error. Do nothing more. */ return 0; #ifdef EAI_OVERFLOW case EAI_OVERFLOW: /* An argument buffer overflowed. */ return EINVAL; /* XXX */ #endif #ifdef EAI_SYSTEM case EAI_SYSTEM: /* System error, obviously. */ return errno; #endif default: /* An error code we haven't handled? */ return EINVAL; } } /* * Resolve the entry in servers with index ind, adding connections to the list * *conns. Connections are added for each of socktype1 and (if not zero) * socktype2. message and udpbufp are used to initialize the connections; see * add_connection above. If no addresses are available for an entry but no * internal name resolution failure occurs, return 0 without adding any new * connections. */ static krb5_error_code resolve_server(krb5_context context, const struct serverlist *servers, size_t ind, int socktype1, int socktype2, const krb5_data *message, char **udpbufp, struct conn_state **conns) { krb5_error_code retval; struct server_entry *entry = &servers->servers[ind]; struct addrinfo *addrs, *a, hint, ai; int err, result; char portbuf[64]; /* Skip any stray entries of socktypes we don't want. */ if (entry->socktype != 0 && entry->socktype != socktype1 && entry->socktype != socktype2) return 0; if (entry->hostname == NULL) { ai.ai_socktype = entry->socktype; ai.ai_family = entry->family; ai.ai_addrlen = entry->addrlen; ai.ai_addr = (struct sockaddr *)&entry->addr; return add_connection(conns, &ai, ind, message, udpbufp); } memset(&hint, 0, sizeof(hint)); hint.ai_family = entry->family; hint.ai_socktype = (entry->socktype != 0) ? entry->socktype : socktype1; hint.ai_flags = AI_ADDRCONFIG; #ifdef AI_NUMERICSERV hint.ai_flags |= AI_NUMERICSERV; #endif result = snprintf(portbuf, sizeof(portbuf), "%d", ntohs(entry->port)); if (SNPRINTF_OVERFLOW(result, sizeof(portbuf))) return EINVAL; TRACE_SENDTO_KDC_RESOLVING(context, entry->hostname); err = getaddrinfo(entry->hostname, portbuf, &hint, &addrs); if (err) return translate_ai_error(err); /* Add each address with the preferred socktype. */ retval = 0; for (a = addrs; a != 0 && retval == 0; a = a->ai_next) retval = add_connection(conns, a, ind, message, udpbufp); if (retval == 0 && entry->socktype == 0 && socktype2 != 0) { /* Add each address again with the non-preferred socktype. */ for (a = addrs; a != 0 && retval == 0; a = a->ai_next) { a->ai_socktype = socktype2; retval = add_connection(conns, a, ind, message, udpbufp); } } freeaddrinfo(addrs); return retval; } static int start_connection(krb5_context context, struct conn_state *state, struct select_state *selstate, struct sendto_callback_info *callback_info) { int fd, e; unsigned int ssflags; static const int one = 1; static const struct linger lopt = { 0, 0 }; dprint("start_connection(@%p)\ngetting %s socket in family %d...", state, state->socktype == SOCK_STREAM ? "stream" : "dgram", state->family); fd = socket(state->family, state->socktype, 0); if (fd == INVALID_SOCKET) { state->err = SOCKET_ERRNO; dprint("socket: %m creating with af %d\n", state->err, state->family); return -1; /* try other hosts */ } set_cloexec_fd(fd); /* Make it non-blocking. */ if (ioctlsocket(fd, FIONBIO, (const void *) &one)) dperror("sendto_kdc: ioctl(FIONBIO)"); if (state->socktype == SOCK_STREAM) { if (setsockopt(fd, SOL_SOCKET, SO_LINGER, &lopt, sizeof(lopt))) dperror("sendto_kdc: setsockopt(SO_LINGER)"); TRACE_SENDTO_KDC_TCP_CONNECT(context, state); } /* Start connecting to KDC. */ e = connect(fd, (struct sockaddr *)&state->addr, state->addrlen); if (e != 0) { /* * This is the path that should be followed for non-blocking * connections. */ if (SOCKET_ERRNO == EINPROGRESS || SOCKET_ERRNO == EWOULDBLOCK) { state->state = CONNECTING; state->fd = fd; } else { dprint("connect failed: %m\n", SOCKET_ERRNO); (void) closesocket(fd); state->err = SOCKET_ERRNO; state->state = FAILED; return -2; } } else { /* * Connect returned zero even though we made it non-blocking. This * happens normally for UDP sockets, and can perhaps also happen for * TCP sockets connecting to localhost. */ state->state = WRITING; state->fd = fd; } dprint("new state = %s\n", state_strings[state->state]); /* * Here's where KPASSWD callback gets the socket information it needs for * a kpasswd request */ if (callback_info) { e = callback_info->pfn_callback(state, callback_info->context, &state->callback_buffer); if (e != 0) { dprint("callback failed: %m\n", e); (void) closesocket(fd); state->err = e; state->fd = INVALID_SOCKET; state->state = FAILED; return -3; } set_conn_state_msg_length(state, &state->callback_buffer); } if (state->socktype == SOCK_DGRAM) { /* Send it now. */ ssize_t ret; sg_buf *sg = &state->x.out.sgbuf[0]; TRACE_SENDTO_KDC_UDP_SEND_INITIAL(context, state); dprint("sending %d bytes on fd %d\n", SG_LEN(sg), state->fd); ret = send(state->fd, SG_BUF(sg), SG_LEN(sg), 0); if (ret < 0 || (size_t) ret != SG_LEN(sg)) { TRACE_SENDTO_KDC_UDP_ERROR_SEND_INITIAL(context, state, SOCKET_ERRNO); dperror("sendto"); (void) closesocket(state->fd); state->fd = INVALID_SOCKET; state->state = FAILED; return -4; } else { state->state = READING; } } ssflags = SSF_READ | SSF_EXCEPTION; if (state->state == CONNECTING || state->state == WRITING) ssflags |= SSF_WRITE; if (!cm_add_fd(selstate, state->fd, ssflags)) { (void) closesocket(state->fd); state->fd = INVALID_SOCKET; state->state = FAILED; return -1; } return 0; } /* Return 0 if we sent something, non-0 otherwise. If 0 is returned, the caller should delay waiting for a response. Otherwise, the caller should immediately move on to process the next connection. */ static int maybe_send(krb5_context context, struct conn_state *conn, struct select_state *selstate, struct sendto_callback_info *callback_info) { sg_buf *sg; ssize_t ret; dprint("maybe_send(@%p) state=%s type=%s\n", conn, state_strings[conn->state], conn->is_udp ? "udp" : "tcp"); if (conn->state == INITIALIZING) return start_connection(context, conn, selstate, callback_info); /* Did we already shut down this channel? */ if (conn->state == FAILED) { dprint("connection already closed\n"); return -1; } if (conn->socktype == SOCK_STREAM) { dprint("skipping stream socket\n"); /* The select callback will handle flushing any data we haven't written yet, and we only write it once. */ return -1; } /* UDP - retransmit after a previous attempt timed out. */ sg = &conn->x.out.sgbuf[0]; TRACE_SENDTO_KDC_UDP_SEND_RETRY(context, conn); dprint("sending %d bytes on fd %d\n", SG_LEN(sg), conn->fd); ret = send(conn->fd, SG_BUF(sg), SG_LEN(sg), 0); if (ret < 0 || (size_t) ret != SG_LEN(sg)) { TRACE_SENDTO_KDC_UDP_ERROR_SEND_RETRY(context, conn, SOCKET_ERRNO); dperror("send"); /* Keep connection alive, we'll try again next pass. Is this likely to catch any errors we didn't get from the select callbacks? */ return -1; } /* Yay, it worked. */ return 0; } static void kill_conn(struct conn_state *conn, struct select_state *selstate, int err) { dprint("abandoning connection %d: %m\n", conn->fd, err); cm_remove_fd(selstate, conn->fd); closesocket(conn->fd); conn->fd = INVALID_SOCKET; conn->state = FAILED; conn->err = err; } /* Check socket for error. */ static int get_so_error(int fd) { int e, sockerr; socklen_t sockerrlen; sockerr = 0; sockerrlen = sizeof(sockerr); e = getsockopt(fd, SOL_SOCKET, SO_ERROR, &sockerr, &sockerrlen); if (e != 0) { /* What to do now? */ e = SOCKET_ERRNO; dprint("getsockopt(SO_ERROR) on fd failed: %m\n", e); return e; } return sockerr; } /* Return nonzero only if we're finished and the caller should exit its loop. This happens in two cases: We have a complete message, or the socket has closed and no others are open. */ static int service_tcp_fd(krb5_context context, struct conn_state *conn, struct select_state *selstate, int ssflags) { int e = 0; ssize_t nwritten, nread; if (!(ssflags & (SSF_READ|SSF_WRITE|SSF_EXCEPTION))) abort(); switch (conn->state) { SOCKET_WRITEV_TEMP tmp; case CONNECTING: if (ssflags & SSF_READ) { /* Bad -- the KDC shouldn't be sending to us first. */ e = EINVAL /* ?? */; kill_conn: TRACE_SENDTO_KDC_TCP_DISCONNECT(context, conn); kill_conn(conn, selstate, e); if (e == EINVAL) { closesocket(conn->fd); conn->fd = INVALID_SOCKET; } return e == 0; } if (ssflags & SSF_EXCEPTION) { handle_exception: e = get_so_error(conn->fd); if (e) dprint("socket error on exception fd: %m", e); else dprint("no socket error info available on exception fd"); goto kill_conn; } /* * Connect finished -- but did it succeed or fail? * UNIX sets can_write if failed. * Call getsockopt to see if error pending. * * (For most UNIX systems it works to just try writing the * first time and detect an error. But Bill Dodd at IBM * reports that some version of AIX, SIGPIPE can result.) */ e = get_so_error(conn->fd); if (e) { TRACE_SENDTO_KDC_TCP_ERROR_CONNECT(context, conn, e); dprint("socket error on write fd: %m", e); goto kill_conn; } conn->state = WRITING; goto try_writing; case WRITING: if (ssflags & SSF_READ) { e = E2BIG; /* Bad -- the KDC shouldn't be sending anything yet. */ goto kill_conn; } if (ssflags & SSF_EXCEPTION) goto handle_exception; try_writing: dprint("trying to writev %d (%d bytes) to fd %d\n", conn->x.out.sg_count, ((conn->x.out.sg_count == 2 ? SG_LEN(&conn->x.out.sgp[1]) : 0) + SG_LEN(&conn->x.out.sgp[0])), conn->fd); TRACE_SENDTO_KDC_TCP_SEND(context, conn); nwritten = SOCKET_WRITEV(conn->fd, conn->x.out.sgp, conn->x.out.sg_count, tmp); if (nwritten < 0) { e = SOCKET_ERRNO; TRACE_SENDTO_KDC_TCP_ERROR_SEND(context, conn, e); dprint("failed: %m\n", e); goto kill_conn; } dprint("wrote %d bytes\n", nwritten); while (nwritten) { sg_buf *sgp = conn->x.out.sgp; if ((size_t) nwritten < SG_LEN(sgp)) { SG_ADVANCE(sgp, (size_t) nwritten); nwritten = 0; } else { nwritten -= SG_LEN(sgp); conn->x.out.sgp++; conn->x.out.sg_count--; if (conn->x.out.sg_count == 0 && nwritten != 0) /* Wrote more than we wanted to? */ abort(); } } if (conn->x.out.sg_count == 0) { /* Done writing, switch to reading. */ /* Don't call shutdown at this point because * some implementations cannot deal with half-closed connections.*/ cm_unset_write(selstate, conn->fd); /* Q: How do we detect failures to send the remaining data to the remote side, since we're in non-blocking mode? Will we always get errors on the reading side? */ dprint("switching fd %d to READING\n", conn->fd); conn->state = READING; conn->x.in.bufsizebytes_read = 0; conn->x.in.bufsize = 0; conn->x.in.buf = 0; conn->x.in.pos = 0; conn->x.in.n_left = 0; } return 0; case READING: if (ssflags & SSF_EXCEPTION) { if (conn->x.in.buf) { free(conn->x.in.buf); conn->x.in.buf = 0; } goto handle_exception; } if (conn->x.in.bufsizebytes_read == 4) { /* Reading data. */ dprint("reading %d bytes of data from fd %d\n", (int) conn->x.in.n_left, conn->fd); nread = SOCKET_READ(conn->fd, conn->x.in.pos, conn->x.in.n_left); if (nread <= 0) { e = nread ? SOCKET_ERRNO : ECONNRESET; free(conn->x.in.buf); conn->x.in.buf = 0; TRACE_SENDTO_KDC_TCP_ERROR_RECV(context, conn, e); goto kill_conn; } conn->x.in.n_left -= nread; conn->x.in.pos += nread; if (conn->x.in.n_left <= 0) { /* We win! */ return 1; } } else { /* Reading length. */ nread = SOCKET_READ(conn->fd, conn->x.in.bufsizebytes + conn->x.in.bufsizebytes_read, 4 - conn->x.in.bufsizebytes_read); if (nread < 0) { TRACE_SENDTO_KDC_TCP_ERROR_RECV_LEN(context, conn, e); e = SOCKET_ERRNO; goto kill_conn; } conn->x.in.bufsizebytes_read += nread; if (conn->x.in.bufsizebytes_read == 4) { unsigned long len = load_32_be (conn->x.in.bufsizebytes); dprint("received length on fd %d is %d\n", conn->fd, (int)len); /* Arbitrary 1M cap. */ if (len > 1 * 1024 * 1024) { e = E2BIG; goto kill_conn; } conn->x.in.bufsize = conn->x.in.n_left = len; conn->x.in.buf = conn->x.in.pos = malloc(len); dprint("allocated %d byte buffer at %p\n", (int) len, conn->x.in.buf); if (conn->x.in.buf == 0) { /* allocation failure */ e = ENOMEM; goto kill_conn; } } } break; default: abort(); } return 0; } static int service_udp_fd(krb5_context context, struct conn_state *conn, struct select_state *selstate, int ssflags) { int nread; if (!(ssflags & (SSF_READ|SSF_EXCEPTION))) abort(); if (conn->state != READING) abort(); nread = recv(conn->fd, conn->x.in.buf, conn->x.in.bufsize, 0); if (nread < 0) { TRACE_SENDTO_KDC_UDP_ERROR_RECV(context, conn, SOCKET_ERRNO); kill_conn(conn, selstate, SOCKET_ERRNO); return 0; } conn->x.in.pos = conn->x.in.buf + nread; return 1; } static krb5_boolean service_fds(krb5_context context, struct select_state *selstate, int interval, struct conn_state *conns, struct select_state *seltemp, int (*msg_handler)(krb5_context, const krb5_data *, void *), void *msg_handler_data, struct conn_state **winner_out) { int e, selret = 0; struct timeval now; struct conn_state *state; *winner_out = NULL; e = k5_getcurtime(&now); if (e) return 1; selstate->end_time = now; selstate->end_time.tv_sec += interval; e = 0; while (selstate->nfds > 0) { e = cm_select_or_poll(selstate, seltemp, &selret); if (e == EINTR) continue; if (e != 0) break; dprint("service_fds examining results, selret=%d\n", selret); if (selret == 0) /* Timeout, return to caller. */ return 0; /* Got something on a socket, process it. */ for (state = conns; state != NULL; state = state->next) { int ssflags; if (state->fd == INVALID_SOCKET) continue; ssflags = cm_get_ssflags(seltemp, state->fd); if (!ssflags) continue; if (state->service(context, state, selstate, ssflags)) { int stop = 1; if (msg_handler != NULL) { krb5_data reply; reply.data = state->x.in.buf; reply.length = state->x.in.pos - state->x.in.buf; stop = (msg_handler(context, &reply, msg_handler_data) != 0); } if (stop) { dprint("fd service routine says we're done\n"); *winner_out = state; return 1; } } } } if (e != 0) return 1; return 0; } /* * Current worst-case timeout behavior: * * First pass, 1s per udp or tcp server, plus 2s at end. * Second pass, 1s per udp server, plus 4s. * Third pass, 1s per udp server, plus 8s. * Fourth => 16s, etc. * * Restated: * Per UDP server, 1s per pass. * Per TCP server, 1s. * Backoff delay, 2**(P+1) - 2, where P is total number of passes. * * Total = 2**(P+1) + U*P + T - 2. * * If P=3, Total = 3*U + T + 14. * If P=4, Total = 4*U + T + 30. * * Note that if you try to reach two ports (e.g., both 88 and 750) on * one server, it counts as two. */ krb5_error_code k5_sendto(krb5_context context, const krb5_data *message, const struct serverlist *servers, int socktype1, int socktype2, struct sendto_callback_info* callback_info, krb5_data *reply, struct sockaddr *remoteaddr, socklen_t *remoteaddrlen, int *server_used, /* return 0 -> keep going, 1 -> quit */ int (*msg_handler)(krb5_context, const krb5_data *, void *), void *msg_handler_data) { int pass, delay; krb5_error_code retval; struct conn_state *conns = NULL, *state, **tailptr, *next, *winner; size_t s; struct select_state *sel_state = NULL, *seltemp; char *udpbuf = NULL; krb5_boolean done = FALSE; reply->data = 0; reply->length = 0; /* One for use here, listing all our fds in use, and one for * temporary use in service_fds, for the fds of interest. */ sel_state = malloc(2 * sizeof(*sel_state)); if (sel_state == NULL) { retval = ENOMEM; goto cleanup; } seltemp = &sel_state[1]; cm_init_selstate(sel_state); /* First pass: resolve server hosts, communicate with resulting addresses * of the preferred socktype, and wait 1s for an answer from each. */ for (s = 0; s < servers->nservers && !done; s++) { /* Find the current tail pointer. */ for (tailptr = &conns; *tailptr != NULL; tailptr = &(*tailptr)->next); retval = resolve_server(context, servers, s, socktype1, socktype2, message, &udpbuf, &conns); if (retval) goto cleanup; for (state = *tailptr; state != NULL && !done; state = state->next) { /* Contact each new connection whose socktype matches socktype1. */ if (state->socktype != socktype1) continue; if (maybe_send(context, state, sel_state, callback_info)) continue; done = service_fds(context, sel_state, 1, conns, seltemp, msg_handler, msg_handler_data, &winner); } } /* Complete the first pass by contacting servers of the non-preferred * socktype (if given), waiting 1s for an answer from each. */ for (state = conns; state != NULL && !done; state = state->next) { if (state->socktype != socktype2) continue; if (maybe_send(context, state, sel_state, callback_info)) continue; done = service_fds(context, sel_state, 1, state, seltemp, msg_handler, msg_handler_data, &winner); } /* Wait for two seconds at the end of the first pass. */ if (!done) { done = service_fds(context, sel_state, 2, conns, seltemp, msg_handler, msg_handler_data, &winner); } /* Make remaining passes over all of the connections. */ delay = 4; for (pass = 1; pass < MAX_PASS && !done; pass++) { for (state = conns; state != NULL && !done; state = state->next) { if (maybe_send(context, state, sel_state, callback_info)) continue; done = service_fds(context, sel_state, 1, conns, seltemp, msg_handler, msg_handler_data, &winner); if (sel_state->nfds == 0) break; } /* Wait for the delay backoff at the end of this pass. */ if (!done) { done = service_fds(context, sel_state, delay, conns, seltemp, msg_handler, msg_handler_data, &winner); } if (sel_state->nfds == 0) break; delay *= 2; } if (sel_state->nfds == 0 || !done || winner == NULL) { retval = KRB5_KDC_UNREACH; goto cleanup; } /* Success! */ TRACE_SENDTO_KDC_RESPONSE(context, winner); reply->data = winner->x.in.buf; reply->length = winner->x.in.pos - winner->x.in.buf; retval = 0; winner->x.in.buf = NULL; if (server_used != NULL) *server_used = winner->server_index; if (remoteaddr != NULL && remoteaddrlen != 0 && *remoteaddrlen > 0) (void)getpeername(winner->fd, remoteaddr, remoteaddrlen); cleanup: for (state = conns; state != NULL; state = next) { next = state->next; if (state->fd != INVALID_SOCKET) closesocket(state->fd); if (state->state == READING && state->x.in.buf != udpbuf) free(state->x.in.buf); if (callback_info) { callback_info->pfn_cleanup(callback_info->context, &state->callback_buffer); } free(state); } if (reply->data != udpbuf) free(udpbuf); free(sel_state); return retval; }