diff options
Diffstat (limited to 'contrib/sendmail/src/domain.c')
| -rw-r--r-- | contrib/sendmail/src/domain.c | 913 |
1 files changed, 913 insertions, 0 deletions
diff --git a/contrib/sendmail/src/domain.c b/contrib/sendmail/src/domain.c new file mode 100644 index 0000000..e3a5500 --- /dev/null +++ b/contrib/sendmail/src/domain.c @@ -0,0 +1,913 @@ +/* + * Copyright (c) 1998 Sendmail, Inc. All rights reserved. + * Copyright (c) 1986, 1995-1997 Eric P. Allman. All rights reserved. + * Copyright (c) 1988, 1993 + * The Regents of the University of California. All rights reserved. + * + * By using this file, you agree to the terms and conditions set + * forth in the LICENSE file which can be found at the top level of + * the sendmail distribution. + * + */ + +#include "sendmail.h" + +#ifndef lint +#if NAMED_BIND +static char sccsid[] = "@(#)domain.c 8.77 (Berkeley) 6/4/98 (with name server)"; +#else +static char sccsid[] = "@(#)domain.c 8.77 (Berkeley) 6/4/98 (without name server)"; +#endif +#endif /* not lint */ + +#if NAMED_BIND + +#include <errno.h> +#include <resolv.h> +#include <arpa/inet.h> + +/* +** The standard udp packet size PACKETSZ (512) is not sufficient for some +** nameserver answers containing very many resource records. The resolver +** may switch to tcp and retry if it detects udp packet overflow. +** Also note that the resolver routines res_query and res_search return +** the size of the *un*truncated answer in case the supplied answer buffer +** it not big enough to accommodate the entire answer. +*/ + +#ifndef MAXPACKET +# define MAXPACKET 8192 /* max packet size used internally by BIND */ +#endif + +typedef union +{ + HEADER qb1; + u_char qb2[MAXPACKET]; +} querybuf; + +#ifndef MXHOSTBUFSIZE +# define MXHOSTBUFSIZE (128 * MAXMXHOSTS) +#endif + +static char MXHostBuf[MXHOSTBUFSIZE]; + +#ifndef MAXDNSRCH +# define MAXDNSRCH 6 /* number of possible domains to search */ +#endif + +#ifndef MAX +# define MAX(a, b) ((a) > (b) ? (a) : (b)) +#endif + +#ifndef NO_DATA +# define NO_DATA NO_ADDRESS +#endif + +#ifndef HFIXEDSZ +# define HFIXEDSZ 12 /* sizeof(HEADER) */ +#endif + +#define MAXCNAMEDEPTH 10 /* maximum depth of CNAME recursion */ + +#if defined(__RES) && (__RES >= 19940415) +# define RES_UNC_T char * +#else +# define RES_UNC_T u_char * +#endif + /* +** GETMXRR -- get MX resource records for a domain +** +** Parameters: +** host -- the name of the host to MX. +** mxhosts -- a pointer to a return buffer of MX records. +** droplocalhost -- If TRUE, all MX records less preferred +** than the local host (as determined by $=w) will +** be discarded. +** rcode -- a pointer to an EX_ status code. +** +** Returns: +** The number of MX records found. +** -1 if there is an internal failure. +** If no MX records are found, mxhosts[0] is set to host +** and 1 is returned. +*/ + +int +getmxrr(host, mxhosts, droplocalhost, rcode) + char *host; + char **mxhosts; + bool droplocalhost; + int *rcode; +{ + register u_char *eom, *cp; + register int i, j, n; + int nmx = 0; + register char *bp; + HEADER *hp; + querybuf answer; + int ancount, qdcount, buflen; + bool seenlocal = FALSE; + u_short pref, type; + u_short localpref = 256; + char *fallbackMX = FallBackMX; + bool trycanon = FALSE; + int (*resfunc)(); + extern int res_query(), res_search(); + u_short prefer[MAXMXHOSTS]; + int weight[MAXMXHOSTS]; + extern int mxrand __P((char *)); + + if (tTd(8, 2)) + printf("getmxrr(%s, droplocalhost=%d)\n", host, droplocalhost); + + if (fallbackMX != NULL && droplocalhost && + wordinclass(fallbackMX, 'w')) + { + /* don't use fallback for this pass */ + fallbackMX = NULL; + } + + *rcode = EX_OK; + + /* efficiency hack -- numeric or non-MX lookups */ + if (host[0] == '[') + goto punt; + + /* + ** If we don't have MX records in our host switch, don't + ** try for MX records. Note that this really isn't "right", + ** since we might be set up to try NIS first and then DNS; + ** if the host is found in NIS we really shouldn't be doing + ** MX lookups. However, that should be a degenerate case. + */ + + if (!UseNameServer) + goto punt; + if (HasWildcardMX && ConfigLevel >= 6) + resfunc = res_query; + else + resfunc = res_search; + + errno = 0; + n = (*resfunc)(host, C_IN, T_MX, (u_char *) &answer, sizeof(answer)); + if (n < 0) + { + if (tTd(8, 1)) + printf("getmxrr: res_search(%s) failed (errno=%d, h_errno=%d)\n", + (host == NULL) ? "<NULL>" : host, errno, h_errno); + switch (h_errno) + { + case NO_DATA: + trycanon = TRUE; + /* fall through */ + + case NO_RECOVERY: + /* no MX data on this host */ + goto punt; + + case HOST_NOT_FOUND: +#if BROKEN_RES_SEARCH + case 0: /* Ultrix resolver retns failure w/ h_errno=0 */ +#endif + /* host doesn't exist in DNS; might be in /etc/hosts */ + trycanon = TRUE; + *rcode = EX_NOHOST; + goto punt; + + case TRY_AGAIN: + case -1: + /* couldn't connect to the name server */ + if (fallbackMX != NULL) + { + /* name server is hosed -- push to fallback */ + mxhosts[nmx++] = fallbackMX; + return nmx; + } + /* it might come up later; better queue it up */ + *rcode = EX_TEMPFAIL; + break; + + default: + syserr("getmxrr: res_search (%s) failed with impossible h_errno (%d)\n", + host, h_errno); + *rcode = EX_OSERR; + break; + } + + /* irreconcilable differences */ + return (-1); + } + + /* avoid problems after truncation in tcp packets */ + if (n > sizeof(answer)) + n = sizeof(answer); + + /* find first satisfactory answer */ + hp = (HEADER *)&answer; + cp = (u_char *)&answer + HFIXEDSZ; + eom = (u_char *)&answer + n; + for (qdcount = ntohs(hp->qdcount); qdcount--; cp += n + QFIXEDSZ) + if ((n = dn_skipname(cp, eom)) < 0) + goto punt; + buflen = sizeof(MXHostBuf) - 1; + bp = MXHostBuf; + ancount = ntohs(hp->ancount); + while (--ancount >= 0 && cp < eom && nmx < MAXMXHOSTS - 1) + { + if ((n = dn_expand((u_char *)&answer, + eom, cp, (RES_UNC_T) bp, buflen)) < 0) + break; + cp += n; + GETSHORT(type, cp); + cp += INT16SZ + INT32SZ; + GETSHORT(n, cp); + if (type != T_MX) + { + if (tTd(8, 8) || _res.options & RES_DEBUG) + printf("unexpected answer type %d, size %d\n", + type, n); + cp += n; + continue; + } + GETSHORT(pref, cp); + if ((n = dn_expand((u_char *)&answer, eom, cp, + (RES_UNC_T) bp, buflen)) < 0) + break; + cp += n; + if (wordinclass(bp, 'w')) + { + if (tTd(8, 3)) + printf("found localhost (%s) in MX list, pref=%d\n", + bp, pref); + if (droplocalhost) + { + if (!seenlocal || pref < localpref) + localpref = pref; + seenlocal = TRUE; + continue; + } + weight[nmx] = 0; + } + else + weight[nmx] = mxrand(bp); + prefer[nmx] = pref; + mxhosts[nmx++] = bp; + n = strlen(bp); + bp += n; + if (bp[-1] != '.') + { + *bp++ = '.'; + n++; + } + *bp++ = '\0'; + buflen -= n + 1; + } + + /* sort the records */ + for (i = 0; i < nmx; i++) + { + for (j = i + 1; j < nmx; j++) + { + if (prefer[i] > prefer[j] || + (prefer[i] == prefer[j] && weight[i] > weight[j])) + { + register int temp; + register char *temp1; + + temp = prefer[i]; + prefer[i] = prefer[j]; + prefer[j] = temp; + temp1 = mxhosts[i]; + mxhosts[i] = mxhosts[j]; + mxhosts[j] = temp1; + temp = weight[i]; + weight[i] = weight[j]; + weight[j] = temp; + } + } + if (seenlocal && prefer[i] >= localpref) + { + /* truncate higher preference part of list */ + nmx = i; + } + } + + /* delete duplicates from list (yes, some bozos have duplicates) */ + for (i = 0; i < nmx - 1; ) + { + if (strcasecmp(mxhosts[i], mxhosts[i + 1]) != 0) + i++; + else + { + /* compress out duplicate */ + for (j = i + 1; j < nmx; j++) + mxhosts[j] = mxhosts[j + 1]; + nmx--; + } + } + + if (nmx == 0) + { +punt: + if (seenlocal && + (!TryNullMXList || sm_gethostbyname(host) == NULL)) + { + /* + ** If we have deleted all MX entries, this is + ** an error -- we should NEVER send to a host that + ** has an MX, and this should have been caught + ** earlier in the config file. + ** + ** Some sites prefer to go ahead and try the + ** A record anyway; that case is handled by + ** setting TryNullMXList. I believe this is a + ** bad idea, but it's up to you.... + */ + + *rcode = EX_CONFIG; + syserr("MX list for %s points back to %s", + host, MyHostName); + return -1; + } + if (strlen(host) >= (SIZE_T) sizeof MXHostBuf) + { + *rcode = EX_CONFIG; + syserr("Host name %s too long", + shortenstring(host, MAXSHORTSTR)); + return -1; + } + snprintf(MXHostBuf, sizeof MXHostBuf, "%s", host); + mxhosts[0] = MXHostBuf; + if (host[0] == '[') + { + register char *p; + + /* this may be an MX suppression-style address */ + p = strchr(MXHostBuf, ']'); + if (p != NULL) + { + *p = '\0'; + if (inet_addr(&MXHostBuf[1]) != INADDR_NONE) + { + nmx++; + *p = ']'; + } + else + { + trycanon = TRUE; + mxhosts[0]++; + } + } + } + if (trycanon && + getcanonname(mxhosts[0], sizeof MXHostBuf - 2, FALSE)) + { + bp = &MXHostBuf[strlen(MXHostBuf)]; + if (bp[-1] != '.') + { + *bp++ = '.'; + *bp = '\0'; + } + nmx = 1; + } + } + + /* if we have a default lowest preference, include that */ + if (fallbackMX != NULL && !seenlocal) + mxhosts[nmx++] = fallbackMX; + + return (nmx); +} + /* +** MXRAND -- create a randomizer for equal MX preferences +** +** If two MX hosts have equal preferences we want to randomize +** the selection. But in order for signatures to be the same, +** we need to randomize the same way each time. This function +** computes a pseudo-random hash function from the host name. +** +** Parameters: +** host -- the name of the host. +** +** Returns: +** A random but repeatable value based on the host name. +** +** Side Effects: +** none. +*/ + +int +mxrand(host) + register char *host; +{ + int hfunc; + static unsigned int seed; + + if (seed == 0) + { + seed = (int) curtime() & 0xffff; + if (seed == 0) + seed++; + } + + if (tTd(17, 9)) + printf("mxrand(%s)", host); + + hfunc = seed; + while (*host != '\0') + { + int c = *host++; + + if (isascii(c) && isupper(c)) + c = tolower(c); + hfunc = ((hfunc << 1) ^ c) % 2003; + } + + hfunc &= 0xff; + hfunc++; + + if (tTd(17, 9)) + printf(" = %d\n", hfunc); + return hfunc; +} + /* +** BESTMX -- find the best MX for a name +** +** This is really a hack, but I don't see any obvious way +** to generalize it at the moment. +*/ + +/* ARGSUSED3 */ +char * +bestmx_map_lookup(map, name, av, statp) + MAP *map; + char *name; + char **av; + int *statp; +{ + int nmx; + auto int rcode; + int saveopts = _res.options; + int i, len = 0; + char *p; + char *mxhosts[MAXMXHOSTS + 1]; + char buf[MXHOSTBUFSIZE + 1]; + + _res.options &= ~(RES_DNSRCH|RES_DEFNAMES); + nmx = getmxrr(name, mxhosts, FALSE, &rcode); + _res.options = saveopts; + if (nmx <= 0) + return NULL; + if (bitset(MF_MATCHONLY, map->map_mflags)) + return map_rewrite(map, name, strlen(name), NULL); + if ((map->map_coldelim == '\0') || (nmx == 1)) + return map_rewrite(map, mxhosts[0], strlen(mxhosts[0]), av); + + /* + ** We were given a -z flag (return all MXs) and there are multiple + ** ones. We need to build them all into a list. + */ + p = buf; + for (i = 0; i < nmx; i++) + { + int slen; + + if (strchr(mxhosts[i], map->map_coldelim) != NULL) + { + syserr("bestmx_map_lookup: MX host %.64s includes map delimiter character 0x%02X", + mxhosts[i], map->map_coldelim); + return NULL; + } + slen = strlen(mxhosts[i]); + if (len + slen + 2 > sizeof buf) + break; + if (i > 0) + { + *p++ = map->map_coldelim; + len++; + } + strcpy(p, mxhosts[i]); + p += slen; + len += slen; + } + return map_rewrite(map, buf, len, av); +} + /* +** DNS_GETCANONNAME -- get the canonical name for named host using DNS +** +** This algorithm tries to be smart about wildcard MX records. +** This is hard to do because DNS doesn't tell is if we matched +** against a wildcard or a specific MX. +** +** We always prefer A & CNAME records, since these are presumed +** to be specific. +** +** If we match an MX in one pass and lose it in the next, we use +** the old one. For example, consider an MX matching *.FOO.BAR.COM. +** A hostname bletch.foo.bar.com will match against this MX, but +** will stop matching when we try bletch.bar.com -- so we know +** that bletch.foo.bar.com must have been right. This fails if +** there was also an MX record matching *.BAR.COM, but there are +** some things that just can't be fixed. +** +** Parameters: +** host -- a buffer containing the name of the host. +** This is a value-result parameter. +** hbsize -- the size of the host buffer. +** trymx -- if set, try MX records as well as A and CNAME. +** statp -- pointer to place to store status. +** +** Returns: +** TRUE -- if the host matched. +** FALSE -- otherwise. +*/ + +bool +dns_getcanonname(host, hbsize, trymx, statp) + char *host; + int hbsize; + bool trymx; + int *statp; +{ + register u_char *eom, *ap; + register char *cp; + register int n; + HEADER *hp; + querybuf answer; + int ancount, qdcount; + int ret; + char **domain; + int type; + char **dp; + char *mxmatch; + bool amatch; + bool gotmx = FALSE; + int qtype; + int loopcnt; + char *xp; + char nbuf[MAX(MAXPACKET, MAXDNAME*2+2)]; + char *searchlist[MAXDNSRCH+2]; + extern char *gethostalias __P((char *)); + + if (tTd(8, 2)) + printf("dns_getcanonname(%s, trymx=%d)\n", host, trymx); + + if ((_res.options & RES_INIT) == 0 && res_init() == -1) + { + *statp = EX_UNAVAILABLE; + return FALSE; + } + + /* + ** Initialize domain search list. If there is at least one + ** dot in the name, search the unmodified name first so we + ** find "vse.CS" in Czechoslovakia instead of in the local + ** domain (e.g., vse.CS.Berkeley.EDU). + ** + ** Older versions of the resolver could create this + ** list by tearing apart the host name. + */ + + loopcnt = 0; +cnameloop: + /* Check for dots in the name */ + for (cp = host, n = 0; *cp != '\0'; cp++) + if (*cp == '.') + n++; + + /* + ** If this is a simple name, determine whether it matches an + ** alias in the file defined by the environment variable HOSTALIASES. + */ + if (n == 0 && (xp = gethostalias(host)) != NULL) + { + if (loopcnt++ > MAXCNAMEDEPTH) + { + syserr("loop in ${HOSTALIASES} file"); + } + else + { + strncpy(host, xp, hbsize); + host[hbsize - 1] = '\0'; + goto cnameloop; + } + } + + /* + ** Build the search list. + ** If there is at least one dot in name, start with a null + ** domain to search the unmodified name first. + ** If name does not end with a dot and search up local domain + ** tree desired, append each local domain component to the + ** search list; if name contains no dots and default domain + ** name is desired, append default domain name to search list; + ** else if name ends in a dot, remove that dot. + */ + + dp = searchlist; + if (n > 0) + *dp++ = ""; + if (n >= 0 && *--cp != '.' && bitset(RES_DNSRCH, _res.options)) + { + for (domain = _res.dnsrch; *domain != NULL; ) + *dp++ = *domain++; + } + else if (n == 0 && bitset(RES_DEFNAMES, _res.options)) + { + *dp++ = _res.defdname; + } + else if (*cp == '.') + { + *cp = '\0'; + } + *dp = NULL; + + /* + ** Now loop through the search list, appending each domain in turn + ** name and searching for a match. + */ + + mxmatch = NULL; + qtype = T_ANY; + + for (dp = searchlist; *dp != NULL; ) + { + if (qtype == T_ANY) + gotmx = FALSE; + if (tTd(8, 5)) + printf("dns_getcanonname: trying %s.%s (%s)\n", + host, *dp, + qtype == T_ANY ? "ANY" : qtype == T_A ? "A" : + qtype == T_MX ? "MX" : "???"); + ret = res_querydomain(host, *dp, C_IN, qtype, + answer.qb2, sizeof(answer.qb2)); + if (ret <= 0) + { + if (tTd(8, 7)) + printf("\tNO: errno=%d, h_errno=%d\n", + errno, h_errno); + + if (errno == ECONNREFUSED || h_errno == TRY_AGAIN) + { + /* the name server seems to be down */ + h_errno = TRY_AGAIN; + *statp = EX_TEMPFAIL; + return FALSE; + } + + if (h_errno != HOST_NOT_FOUND) + { + /* might have another type of interest */ + if (qtype == T_ANY) + { + qtype = T_A; + continue; + } + else if (qtype == T_A && !gotmx && trymx) + { + qtype = T_MX; + continue; + } + } + + /* definite no -- try the next domain */ + dp++; + qtype = T_ANY; + continue; + } + else if (tTd(8, 7)) + printf("\tYES\n"); + + /* avoid problems after truncation in tcp packets */ + if (ret > sizeof(answer)) + ret = sizeof(answer); + + /* + ** Appear to have a match. Confirm it by searching for A or + ** CNAME records. If we don't have a local domain + ** wild card MX record, we will accept MX as well. + */ + + hp = (HEADER *) &answer; + ap = (u_char *) &answer + HFIXEDSZ; + eom = (u_char *) &answer + ret; + + /* skip question part of response -- we know what we asked */ + for (qdcount = ntohs(hp->qdcount); qdcount--; ap += ret + QFIXEDSZ) + { + if ((ret = dn_skipname(ap, eom)) < 0) + { + if (tTd(8, 20)) + printf("qdcount failure (%d)\n", + ntohs(hp->qdcount)); + *statp = EX_SOFTWARE; + return FALSE; /* ???XXX??? */ + } + } + + amatch = FALSE; + for (ancount = ntohs(hp->ancount); --ancount >= 0 && ap < eom; + ap += n) + { + n = dn_expand((u_char *) &answer, eom, ap, + (RES_UNC_T) nbuf, sizeof nbuf); + if (n < 0) + break; + ap += n; + GETSHORT(type, ap); + ap += INT16SZ + INT32SZ; + GETSHORT(n, ap); + switch (type) + { + case T_MX: + gotmx = TRUE; + if (**dp != '\0' && HasWildcardMX) + { + /* + ** If we are using MX matches and have + ** not yet gotten one, save this one + ** but keep searching for an A or + ** CNAME match. + */ + + if (trymx && mxmatch == NULL) + mxmatch = *dp; + continue; + } + + /* + ** If we did not append a domain name, this + ** must have been a canonical name to start + ** with. Even if we did append a domain name, + ** in the absence of a wildcard MX this must + ** still be a real MX match. + ** Such MX matches are as good as an A match, + ** fall through. + */ + + case T_A: + /* Flag that a good match was found */ + amatch = TRUE; + + /* continue in case a CNAME also exists */ + continue; + + case T_CNAME: + if (DontExpandCnames) + { + /* got CNAME -- guaranteed canonical */ + amatch = TRUE; + break; + } + + if (loopcnt++ > MAXCNAMEDEPTH) + { + /*XXX should notify postmaster XXX*/ + message("DNS failure: CNAME loop for %s", + host); + if (CurEnv->e_message == NULL) + { + char ebuf[MAXLINE]; + + snprintf(ebuf, sizeof ebuf, + "Deferred: DNS failure: CNAME loop for %.100s", + host); + CurEnv->e_message = newstr(ebuf); + } + h_errno = NO_RECOVERY; + *statp = EX_CONFIG; + return FALSE; + } + + /* value points at name */ + if ((ret = dn_expand((u_char *)&answer, + eom, ap, (RES_UNC_T) nbuf, sizeof(nbuf))) < 0) + break; + (void)strncpy(host, nbuf, hbsize); /* XXX */ + host[hbsize - 1] = '\0'; + + /* + ** RFC 1034 section 3.6 specifies that CNAME + ** should point at the canonical name -- but + ** urges software to try again anyway. + */ + + goto cnameloop; + + default: + /* not a record of interest */ + continue; + } + } + + if (amatch) + { + /* + ** Got a good match -- either an A, CNAME, or an + ** exact MX record. Save it and get out of here. + */ + + mxmatch = *dp; + break; + } + + /* + ** Nothing definitive yet. + ** If this was a T_ANY query, we don't really know what + ** was returned -- it might have been a T_NS, + ** for example. Try T_A to be more specific + ** during the next pass. + ** If this was a T_A query and we haven't yet found a MX + ** match, try T_MX if allowed to do so. + ** Otherwise, try the next domain. + */ + + if (qtype == T_ANY) + qtype = T_A; + else if (qtype == T_A && !gotmx && trymx) + qtype = T_MX; + else + { + qtype = T_ANY; + dp++; + } + } + + /* if nothing was found, we are done */ + if (mxmatch == NULL) + { + *statp = EX_NOHOST; + return FALSE; + } + + /* + ** Create canonical name and return. + ** If saved domain name is null, name was already canonical. + ** Otherwise append the saved domain name. + */ + + (void) snprintf(nbuf, sizeof nbuf, "%.*s%s%.*s", MAXDNAME, host, + *mxmatch == '\0' ? "" : ".", + MAXDNAME, mxmatch); + strncpy(host, nbuf, hbsize); + host[hbsize - 1] = '\0'; + if (tTd(8, 5)) + printf("dns_getcanonname: %s\n", host); + *statp = EX_OK; + return TRUE; +} + + + +char * +gethostalias(host) + char *host; +{ + char *fname; + FILE *fp; + register char *p = NULL; + int sff = SFF_REGONLY; + char buf[MAXLINE]; + static char hbuf[MAXDNAME]; + + if (DontLockReadFiles) + sff |= SFF_NOLOCK; + fname = getenv("HOSTALIASES"); + if (fname == NULL || + (fp = safefopen(fname, O_RDONLY, 0, sff)) == NULL) + return NULL; + while (fgets(buf, sizeof buf, fp) != NULL) + { + for (p = buf; p != '\0' && !(isascii(*p) && isspace(*p)); p++) + continue; + if (*p == 0) + { + /* syntax error */ + continue; + } + *p++ = '\0'; + if (strcasecmp(buf, host) == 0) + break; + } + + if (feof(fp)) + { + /* no match */ + fclose(fp); + return NULL; + } + fclose(fp); + + /* got a match; extract the equivalent name */ + while (*p != '\0' && isascii(*p) && isspace(*p)) + p++; + host = p; + while (*p != '\0' && !(isascii(*p) && isspace(*p))) + p++; + *p = '\0'; + strncpy(hbuf, host, sizeof hbuf - 1); + hbuf[sizeof hbuf - 1] = '\0'; + return hbuf; +} + +#endif /* NAMED_BIND */ |
