diff options
Diffstat (limited to 'openbsd-compat/libasr/res_send_async.c')
| -rw-r--r-- | openbsd-compat/libasr/res_send_async.c | 806 |
1 files changed, 806 insertions, 0 deletions
diff --git a/openbsd-compat/libasr/res_send_async.c b/openbsd-compat/libasr/res_send_async.c new file mode 100644 index 00000000..7eeeef48 --- /dev/null +++ b/openbsd-compat/libasr/res_send_async.c @@ -0,0 +1,806 @@ +/* $OpenBSD: res_send_async.c,v 1.39 2019/09/28 11:21:07 eric Exp $ */ +/* + * Copyright (c) 2012 Eric Faurot <eric@openbsd.org> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include "includes.h" + +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/uio.h> +#include <netinet/in.h> +#include <arpa/nameser.h> +#ifdef HAVE_ARPA_NAMESER_COMPAT_H +#include <arpa/nameser_compat.h> +#endif +#include <netdb.h> + +#include <asr.h> +#include <errno.h> +#include <fcntl.h> +#include <poll.h> +#include <resolv.h> /* for res_random */ +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "asr_private.h" + +#define OP_QUERY (0) + +static int res_send_async_run(struct asr_query *, struct asr_result *); +static int sockaddr_connect(const struct sockaddr *, int); +static int udp_send(struct asr_query *); +static int udp_recv(struct asr_query *); +static int tcp_write(struct asr_query *); +static int tcp_read(struct asr_query *); +static int validate_packet(struct asr_query *); +static int setup_query(struct asr_query *, const char *, const char *, int, int); +static int ensure_ibuf(struct asr_query *, size_t); +static int iter_ns(struct asr_query *); + +#define AS_NS_SA(p) ((p)->as_ctx->ac_ns[(p)->as.dns.nsidx - 1]) + + +struct asr_query * +res_send_async(const unsigned char *buf, int buflen, void *asr) +{ + struct asr_ctx *ac; + struct asr_query *as; + struct asr_unpack p; + struct asr_dns_header h; + struct asr_dns_query q; + + DPRINT_PACKET("asr: res_send_async()", buf, buflen); + + ac = _asr_use_resolver(asr); + if ((as = _asr_async_new(ac, ASR_SEND)) == NULL) { + _asr_ctx_unref(ac); + return (NULL); /* errno set */ + } + as->as_run = res_send_async_run; + + as->as_flags |= ASYNC_EXTOBUF; + as->as.dns.obuf = (unsigned char *)buf; + as->as.dns.obuflen = buflen; + as->as.dns.obufsize = buflen; + + _asr_unpack_init(&p, buf, buflen); + _asr_unpack_header(&p, &h); + _asr_unpack_query(&p, &q); + if (p.err) { + errno = EINVAL; + goto err; + } + as->as.dns.reqid = h.id; + as->as.dns.type = q.q_type; + as->as.dns.class = q.q_class; + as->as.dns.dname = strdup(q.q_dname); + if (as->as.dns.dname == NULL) + goto err; /* errno set */ + + _asr_ctx_unref(ac); + return (as); + err: + if (as) + _asr_async_free(as); + _asr_ctx_unref(ac); + return (NULL); +} +DEF_WEAK(res_send_async); + +/* + * Unlike res_query(), this version will actually return the packet + * if it has received a valid one (errno == 0) even if h_errno is + * not NETDB_SUCCESS. So the packet *must* be freed if necessary. + */ +struct asr_query * +res_query_async(const char *name, int class, int type, void *asr) +{ + struct asr_ctx *ac; + struct asr_query *as; + + DPRINT("asr: res_query_async(\"%s\", %i, %i)\n", name, class, type); + + ac = _asr_use_resolver(asr); + as = _res_query_async_ctx(name, class, type, ac); + _asr_ctx_unref(ac); + + return (as); +} +DEF_WEAK(res_query_async); + +struct asr_query * +_res_query_async_ctx(const char *name, int class, int type, struct asr_ctx *a_ctx) +{ + struct asr_query *as; + + DPRINT("asr: res_query_async_ctx(\"%s\", %i, %i)\n", name, class, type); + + if ((as = _asr_async_new(a_ctx, ASR_SEND)) == NULL) + return (NULL); /* errno set */ + as->as_run = res_send_async_run; + + /* This adds a "." to name if it doesn't already has one. + * That's how res_query() behaves (through res_mkquery"). + */ + if (setup_query(as, name, NULL, class, type) == -1) + goto err; /* errno set */ + + return (as); + + err: + if (as) + _asr_async_free(as); + + return (NULL); +} + +static int +res_send_async_run(struct asr_query *as, struct asr_result *ar) +{ + next: + switch (as->as_state) { + + case ASR_STATE_INIT: + + if (as->as_ctx->ac_nscount == 0) { + ar->ar_errno = ECONNREFUSED; + async_set_state(as, ASR_STATE_HALT); + break; + } + + async_set_state(as, ASR_STATE_NEXT_NS); + break; + + case ASR_STATE_NEXT_NS: + + if (iter_ns(as) == -1) { + ar->ar_errno = ETIMEDOUT; + async_set_state(as, ASR_STATE_HALT); + break; + } + + if (as->as_ctx->ac_options & RES_USEVC || + as->as.dns.obuflen > PACKETSZ) + async_set_state(as, ASR_STATE_TCP_WRITE); + else + async_set_state(as, ASR_STATE_UDP_SEND); + break; + + case ASR_STATE_UDP_SEND: + + if (udp_send(as) == -1) { + async_set_state(as, ASR_STATE_NEXT_NS); + break; + } + async_set_state(as, ASR_STATE_UDP_RECV); + ar->ar_cond = ASR_WANT_READ; + ar->ar_fd = as->as_fd; + ar->ar_timeout = as->as_timeout; + return (ASYNC_COND); + break; + + case ASR_STATE_UDP_RECV: + + if (udp_recv(as) == -1) { + if (errno == ENOMEM) { + ar->ar_errno = errno; + async_set_state(as, ASR_STATE_HALT); + break; + } + if (errno != EOVERFLOW) { + /* Fail or timeout */ + async_set_state(as, ASR_STATE_NEXT_NS); + break; + } + if (as->as_ctx->ac_options & RES_IGNTC) + async_set_state(as, ASR_STATE_PACKET); + else + async_set_state(as, ASR_STATE_TCP_WRITE); + } else + async_set_state(as, ASR_STATE_PACKET); + break; + + case ASR_STATE_TCP_WRITE: + + switch (tcp_write(as)) { + case -1: /* fail or timeout */ + async_set_state(as, ASR_STATE_NEXT_NS); + break; + case 0: + async_set_state(as, ASR_STATE_TCP_READ); + ar->ar_cond = ASR_WANT_READ; + ar->ar_fd = as->as_fd; + ar->ar_timeout = as->as_timeout; + return (ASYNC_COND); + case 1: + ar->ar_cond = ASR_WANT_WRITE; + ar->ar_fd = as->as_fd; + ar->ar_timeout = as->as_timeout; + return (ASYNC_COND); + } + break; + + case ASR_STATE_TCP_READ: + + switch (tcp_read(as)) { + case -1: /* Fail or timeout */ + if (errno == ENOMEM) { + ar->ar_errno = errno; + async_set_state(as, ASR_STATE_HALT); + } else + async_set_state(as, ASR_STATE_NEXT_NS); + break; + case 0: + async_set_state(as, ASR_STATE_PACKET); + break; + case 1: + ar->ar_cond = ASR_WANT_READ; + ar->ar_fd = as->as_fd; + ar->ar_timeout = as->as_timeout; + return (ASYNC_COND); + } + break; + + case ASR_STATE_PACKET: + + memmove(&ar->ar_ns, AS_NS_SA(as), SA_LEN(AS_NS_SA(as))); + ar->ar_datalen = as->as.dns.ibuflen; + ar->ar_data = as->as.dns.ibuf; + as->as.dns.ibuf = NULL; + ar->ar_errno = 0; + ar->ar_rcode = as->as.dns.rcode; + async_set_state(as, ASR_STATE_HALT); + break; + + case ASR_STATE_HALT: + + if (ar->ar_errno) { + ar->ar_h_errno = TRY_AGAIN; + ar->ar_count = 0; + ar->ar_datalen = -1; + ar->ar_data = NULL; + } else if (as->as.dns.ancount) { + ar->ar_h_errno = NETDB_SUCCESS; + ar->ar_count = as->as.dns.ancount; + } else { + ar->ar_count = 0; + switch (as->as.dns.rcode) { + case NXDOMAIN: + ar->ar_h_errno = HOST_NOT_FOUND; + break; + case SERVFAIL: + ar->ar_h_errno = TRY_AGAIN; + break; + case NOERROR: + ar->ar_h_errno = NO_DATA; + break; + default: + ar->ar_h_errno = NO_RECOVERY; + } + } + return (ASYNC_DONE); + + default: + + ar->ar_errno = EOPNOTSUPP; + ar->ar_h_errno = NETDB_INTERNAL; + async_set_state(as, ASR_STATE_HALT); + break; + } + goto next; +} + +static int +sockaddr_connect(const struct sockaddr *sa, int socktype) +{ + int errno_save, sock, flags; + + if ((sock = socket(sa->sa_family, socktype, 0)) == -1) + goto fail; + + if ((flags = fcntl(sock, F_GETFL, 0)) == -1) + goto fail; + + flags |= O_NONBLOCK; + + if ((flags = fcntl(sock, F_SETFL, flags)) == -1) + goto fail; + + if (connect(sock, sa, SA_LEN(sa)) == -1) { + /* + * In the TCP case, the caller will be asked to poll for + * POLLOUT so that we start writing the packet in tcp_write() + * when the connection is established, or fail there on error. + */ + if (errno == EINPROGRESS) + return (sock); + goto fail; + } + + return (sock); + + fail: + + if (sock != -1) { + errno_save = errno; + close(sock); + errno = errno_save; + } + + return (-1); +} + +/* + * Prepare the DNS packet for the query type "type", class "class" and domain + * name created by the concatenation on "name" and "dom". + * Return 0 on success, set errno and return -1 on error. + */ +static int +setup_query(struct asr_query *as, const char *name, const char *dom, + int class, int type) +{ + struct asr_pack p; + struct asr_dns_header h; + char fqdn[MAXDNAME]; + char dname[MAXDNAME]; + + if (as->as_flags & ASYNC_EXTOBUF) { + errno = EINVAL; + DPRINT("attempting to write in user packet"); + return (-1); + } + + if (_asr_make_fqdn(name, dom, fqdn, sizeof(fqdn)) > sizeof(fqdn)) { + errno = EINVAL; + DPRINT("asr_make_fqdn: name too long\n"); + return (-1); + } + + if (_asr_dname_from_fqdn(fqdn, dname, sizeof(dname)) == -1) { + errno = EINVAL; + DPRINT("asr_dname_from_fqdn: invalid\n"); + return (-1); + } + + if (as->as.dns.obuf == NULL) { + as->as.dns.obufsize = PACKETSZ; + as->as.dns.obuf = malloc(as->as.dns.obufsize); + if (as->as.dns.obuf == NULL) + return (-1); /* errno set */ + } + as->as.dns.obuflen = 0; + + memset(&h, 0, sizeof h); + h.id = res_randomid(); + if (as->as_ctx->ac_options & RES_RECURSE) + h.flags |= RD_MASK; +#ifdef RES_USE_CD + if (as->as_ctx->ac_options & RES_USE_CD) + h.flags |= CD_MASK; +#endif + h.qdcount = 1; + if (as->as_ctx->ac_options & (RES_USE_EDNS0 | RES_USE_DNSSEC)) + h.arcount = 1; + + _asr_pack_init(&p, as->as.dns.obuf, as->as.dns.obufsize); + _asr_pack_header(&p, &h); + _asr_pack_query(&p, type, class, dname); + if (as->as_ctx->ac_options & (RES_USE_EDNS0 | RES_USE_DNSSEC)) + _asr_pack_edns0(&p, MAXPACKETSZ, + as->as_ctx->ac_options & RES_USE_DNSSEC); + if (p.err) { + DPRINT("error packing query"); + errno = EINVAL; + return (-1); + } + + /* Remember the parameters. */ + as->as.dns.reqid = h.id; + as->as.dns.type = type; + as->as.dns.class = class; + if (as->as.dns.dname) + free(as->as.dns.dname); + as->as.dns.dname = strdup(dname); + if (as->as.dns.dname == NULL) { + DPRINT("strdup"); + return (-1); /* errno set */ + } + as->as.dns.obuflen = p.offset; + + DPRINT_PACKET("asr_setup_query", as->as.dns.obuf, as->as.dns.obuflen); + + return (0); +} + +/* + * Create a connect UDP socket and send the output packet. + * + * Return 0 on success, or -1 on error (errno set). + */ +static int +udp_send(struct asr_query *as) +{ + ssize_t n; + int save_errno; +#ifdef DEBUG + char buf[256]; +#endif + + DPRINT("asr: [%p] connecting to %s UDP\n", as, + _asr_print_sockaddr(AS_NS_SA(as), buf, sizeof buf)); + + as->as_fd = sockaddr_connect(AS_NS_SA(as), SOCK_DGRAM); + if (as->as_fd == -1) + return (-1); /* errno set */ + + n = send(as->as_fd, as->as.dns.obuf, as->as.dns.obuflen, 0); + if (n == -1) { + save_errno = errno; + close(as->as_fd); + errno = save_errno; + as->as_fd = -1; + return (-1); + } + + return (0); +} + +/* + * Try to receive a valid packet from the current UDP socket. + * + * Return 0 if a full packet could be read, or -1 on error (errno set). + */ +static int +udp_recv(struct asr_query *as) +{ + ssize_t n; + int save_errno; + + if (ensure_ibuf(as, MAXPACKETSZ) == -1) { + save_errno = errno; + close(as->as_fd); + errno = save_errno; + as->as_fd = -1; + return (-1); + } + + n = recv(as->as_fd, as->as.dns.ibuf, as->as.dns.ibufsize, 0); + save_errno = errno; + close(as->as_fd); + errno = save_errno; + as->as_fd = -1; + if (n == -1) + return (-1); + + as->as.dns.ibuflen = n; + + DPRINT_PACKET("asr_udp_recv()", as->as.dns.ibuf, as->as.dns.ibuflen); + + if (validate_packet(as) == -1) + return (-1); /* errno set */ + + return (0); +} + +/* + * Write the output packet to the TCP socket. + * + * Return 0 when all bytes have been sent, 1 there is no buffer space on the + * socket or it is not connected yet, or -1 on error (errno set). + */ +static int +tcp_write(struct asr_query *as) +{ + struct msghdr msg; + struct iovec iov[2]; + uint16_t len; + ssize_t n; + size_t offset; + int i; +#ifdef DEBUG + char buf[256]; +#endif + + /* First try to connect if not already */ + if (as->as_fd == -1) { + DPRINT("asr: [%p] connecting to %s TCP\n", as, + _asr_print_sockaddr(AS_NS_SA(as), buf, sizeof buf)); + as->as_fd = sockaddr_connect(AS_NS_SA(as), SOCK_STREAM); + if (as->as_fd == -1) + return (-1); /* errno set */ +/* + * Some systems (MacOS X) have SO_NOSIGPIPE instead of MSG_NOSIGNAL. + * If neither is available the system is probably broken. We might + * want to detect this at configure time. + */ +#ifdef SO_NOSIGPIPE + i = 1; + if (setsockopt(as->as_fd, SOL_SOCKET, SO_NOSIGPIPE, (void *)&i, + sizeof(i)) == -1) + return (-1); /* errno set */ +#endif + as->as.dns.datalen = 0; /* bytes sent */ + return (1); + } + + i = 0; + + /* Prepend de packet length if not sent already. */ + if (as->as.dns.datalen < sizeof(len)) { + offset = 0; + len = htons(as->as.dns.obuflen); + iov[i].iov_base = (char *)(&len) + as->as.dns.datalen; + iov[i].iov_len = sizeof(len) - as->as.dns.datalen; + i++; + } else + offset = as->as.dns.datalen - sizeof(len); + + iov[i].iov_base = as->as.dns.obuf + offset; + iov[i].iov_len = as->as.dns.obuflen - offset; + i++; + + memset(&msg, 0, sizeof msg); + msg.msg_iov = iov; + msg.msg_iovlen = i; + + send_again: +/* See above. */ +#ifndef MSG_NOSIGNAL +#define MSG_NOSIGNAL 0 +#endif + n = sendmsg(as->as_fd, &msg, MSG_NOSIGNAL); + if (n == -1) { + if (errno == EINTR) + goto send_again; + goto close; /* errno set */ + } + + as->as.dns.datalen += n; + + if (as->as.dns.datalen == as->as.dns.obuflen + sizeof(len)) { + /* All sent. Prepare for TCP read */ + as->as.dns.datalen = 0; + return (0); + } + + /* More data to write */ + return (1); + +close: + close(as->as_fd); + as->as_fd = -1; + return (-1); +} + +/* + * Try to read a valid packet from the current TCP socket. + * + * Return 0 if a full packet could be read, 1 if more data is needed and the + * socket must be read again, or -1 on error (errno set). + */ +static int +tcp_read(struct asr_query *as) +{ + ssize_t n; + size_t offset, len; + char *pos; + int save_errno, nfds; + struct pollfd pfd; + + /* We must read the packet len first */ + if (as->as.dns.datalen < sizeof(as->as.dns.pktlen)) { + + pos = (char *)(&as->as.dns.pktlen) + as->as.dns.datalen; + len = sizeof(as->as.dns.pktlen) - as->as.dns.datalen; + + read_again0: + n = read(as->as_fd, pos, len); + if (n == -1) { + if (errno == EINTR) + goto read_again0; + goto close; /* errno set */ + } + if (n == 0) { + errno = ECONNRESET; + goto close; + } + as->as.dns.datalen += n; + if (as->as.dns.datalen < sizeof(as->as.dns.pktlen)) + return (1); /* need more data */ + + as->as.dns.ibuflen = ntohs(as->as.dns.pktlen); + if (ensure_ibuf(as, as->as.dns.ibuflen) == -1) + goto close; /* errno set */ + + pfd.fd = as->as_fd; + pfd.events = POLLIN; + poll_again: + nfds = poll(&pfd, 1, 0); + if (nfds == -1) { + if (errno == EINTR) + goto poll_again; + goto close; /* errno set */ + } + if (nfds == 0) + return (1); /* no more data available */ + } + + offset = as->as.dns.datalen - sizeof(as->as.dns.pktlen); + pos = as->as.dns.ibuf + offset; + len = as->as.dns.ibuflen - offset; + + read_again: + n = read(as->as_fd, pos, len); + if (n == -1) { + if (errno == EINTR) + goto read_again; + goto close; /* errno set */ + } + if (n == 0) { + errno = ECONNRESET; + goto close; + } + as->as.dns.datalen += n; + + /* See if we got all the advertised bytes. */ + if (as->as.dns.datalen != as->as.dns.ibuflen + sizeof(as->as.dns.pktlen)) + return (1); + + DPRINT_PACKET("asr_tcp_read()", as->as.dns.ibuf, as->as.dns.ibuflen); + + if (validate_packet(as) == -1) + goto close; /* errno set */ + + errno = 0; +close: + save_errno = errno; + close(as->as_fd); + errno = save_errno; + as->as_fd = -1; + return (errno ? -1 : 0); +} + +/* + * Make sure the input buffer is at least "n" bytes long, and allocate or + * extend it if necessary. Return 0 on success, or set errno and return -1. + */ +static int +ensure_ibuf(struct asr_query *as, size_t n) +{ + char *t; + + if (as->as.dns.ibufsize >= n) + return (0); + + t = recallocarray(as->as.dns.ibuf, as->as.dns.ibufsize, n, 1); + if (t == NULL) + return (-1); /* errno set */ + as->as.dns.ibuf = t; + as->as.dns.ibufsize = n; + + return (0); +} + +/* + * Check if the received packet is valid. + * Return 0 on success, or set errno and return -1. + */ +static int +validate_packet(struct asr_query *as) +{ + struct asr_unpack p; + struct asr_dns_header h; + struct asr_dns_query q; + struct asr_dns_rr rr; + int r; + + _asr_unpack_init(&p, as->as.dns.ibuf, as->as.dns.ibuflen); + + _asr_unpack_header(&p, &h); + if (p.err) + goto inval; + + if (h.id != as->as.dns.reqid) { + DPRINT("incorrect reqid\n"); + goto inval; + } + if (h.qdcount != 1) + goto inval; + /* Should be zero, we could allow this */ + if ((h.flags & Z_MASK) != 0) + goto inval; + /* Actually, it depends on the request but we only use OP_QUERY */ + if (OPCODE(h.flags) != OP_QUERY) + goto inval; + /* Must be a response */ + if ((h.flags & QR_MASK) == 0) + goto inval; + + as->as.dns.rcode = RCODE(h.flags); + as->as.dns.ancount = h.ancount; + + _asr_unpack_query(&p, &q); + if (p.err) + goto inval; + + if (q.q_type != as->as.dns.type || + q.q_class != as->as.dns.class || + strcasecmp(q.q_dname, as->as.dns.dname)) { + DPRINT("incorrect type/class/dname '%s' != '%s'\n", + q.q_dname, as->as.dns.dname); + goto inval; + } + + /* Check for truncation */ + if (h.flags & TC_MASK && !(as->as_ctx->ac_options & RES_IGNTC)) { + DPRINT("truncated\n"); + errno = EOVERFLOW; + return (-1); + } + + /* Validate the rest of the packet */ + for (r = h.ancount + h.nscount + h.arcount; r; r--) + _asr_unpack_rr(&p, &rr); + + /* Report any error found when unpacking the RRs. */ + if (p.err) { + DPRINT("unpack: %s\n", strerror(p.err)); + errno = p.err; + return (-1); + } + + if (p.offset != as->as.dns.ibuflen) { + DPRINT("trailing garbage\n"); + errno = EMSGSIZE; + return (-1); + } + + return (0); + + inval: + errno = EINVAL; + return (-1); +} + +/* + * Set the async context nameserver index to the next nameserver, cycling + * over the list until the maximum retry counter is reached. Return 0 on + * success, or -1 if all nameservers were used. + */ +static int +iter_ns(struct asr_query *as) +{ + for (;;) { + if (as->as.dns.nsloop >= as->as_ctx->ac_nsretries) + return (-1); + + as->as.dns.nsidx += 1; + if (as->as.dns.nsidx <= as->as_ctx->ac_nscount) + break; + as->as.dns.nsidx = 0; + as->as.dns.nsloop++; + DPRINT("asr: iter_ns(): cycle %i\n", as->as.dns.nsloop); + } + + as->as_timeout = 1000 * (as->as_ctx->ac_nstimeout << as->as.dns.nsloop); + if (as->as.dns.nsloop > 0) + as->as_timeout /= as->as_ctx->ac_nscount; + if (as->as_timeout < 1000) + as->as_timeout = 1000; + + return (0); +} |