#include "common.h" #include #include "smtp.h" /* to publish dial_string_parse */ #include enum { Nmx= 16, Maxstring= 256 }; typedef struct Mx Mx; struct Mx { char host[256]; char ip[24]; int pref; }; static Mx mx[Nmx]; Ndb *db; extern int debug; static int mxlookup(DS*, char*); static int compar(const void*, const void*); static int callmx(DS*, char*, char*); static void expand_meta(DS *ds); extern int cistrcmp(char*, char*); int mxdial(char *addr, char *ddomain, char *gdomain) { int fd; DS ds; char err[Errlen]; addr = netmkaddr(addr, 0, "smtp"); dial_string_parse(addr, &ds); /* try connecting to destination or any of it's mail routers */ fd = callmx(&ds, addr, ddomain); /* try our mail gateway */ rerrstr(err, sizeof(err)); if(fd < 0 && gdomain && strstr(err, "can't translate") != 0) fd = dial(netmkaddr(gdomain, 0, "smtp"), 0, 0, 0); return fd; } static int timeout(void *v, char *msg) { USED(v); if(strstr(msg, "alarm")) return 1; return 0; } /* * take an address and return all the mx entries for it, * most preferred first */ static int callmx(DS *ds, char *dest, char *domain) { int fd, i, nmx; char addr[Maxstring]; /* get a list of mx entries */ nmx = mxlookup(ds, domain); if(nmx < 0){ /* dns isn't working, don't just dial */ return -1; } if(nmx == 0){ if(debug) fprint(2, "mxlookup returns nothing\n"); return dial(dest, 0, 0, 0); } /* refuse to honor loopback addresses given by dns */ for(i = 0; i < nmx; i++){ if(strcmp(mx[i].ip, "127.0.0.1") == 0){ if(debug) fprint(2, "mxlookup returns loopback\n"); werrstr("illegal: domain lists 127.0.0.1 as mail server"); return -1; } } /* sort by preference */ if(nmx > 1) qsort(mx, nmx, sizeof(Mx), compar); if(debug){ for(i=0; iproto, mx[i].host, ds->service); if(debug) fprint(2, "mxdial trying %s (%d)\n", addr, i); atnotify(timeout, 1); alarm(10*1000); fd = dial(addr, 0, 0, 0); alarm(0); atnotify(timeout, 0); if(fd >= 0) return fd; } return -1; } /* * use dns to resolve the mx request */ static int mxlookup(DS *ds, char *domain) { int i, n, nmx; Ndbtuple *t, *tmx, *tpref, *tip; strcpy(domain, ds->host); ds->netdir = "/net"; nmx = 0; if((t = dnsquery(nil, ds->host, "mx")) != nil){ for(tmx=t; (tmx=ndbfindattr(tmx->entry, nil, "mx")) != nil && nmxline; tpref != tmx; tpref=tpref->line){ if(strcmp(tpref->attr, "pref") == 0){ strncpy(mx[nmx].host, tmx->val, sizeof(mx[n].host)-1); mx[nmx].pref = atoi(tpref->val); nmx++; break; } } } ndbfree(t); } /* * no mx record? try name itself. */ /* * BUG? If domain has no dots, then we used to look up ds->host * but return domain instead of ds->host in the list. Now we return * ds->host. What will this break? */ if(nmx == 0){ mx[0].pref = 1; strncpy(mx[0].host, ds->host, sizeof(mx[0].host)); nmx++; } /* * look up all ip addresses */ for(i = 0; i < nmx; i++){ if((t = dnsquery(nil, mx[i].host, "ip")) == nil) goto no; if((tip = ndbfindattr(t, nil, "ip")) == nil){ ndbfree(t); goto no; } strncpy(mx[i].ip, tip->val, sizeof(mx[i].ip)-1); ndbfree(t); continue; no: /* remove mx[i] and go around again */ nmx--; mx[i] = mx[nmx]; i--; } return nmx; } static int compar(const void *a, const void *b) { return ((Mx*)a)->pref - ((Mx*)b)->pref; } /* break up an address to its component parts */ void dial_string_parse(char *str, DS *ds) { char *p, *p2; strncpy(ds->buf, str, sizeof(ds->buf)); ds->buf[sizeof(ds->buf)-1] = 0; p = strchr(ds->buf, '!'); if(p == 0) { ds->netdir = 0; ds->proto = "net"; ds->host = ds->buf; } else { if(*ds->buf != '/'){ ds->netdir = 0; ds->proto = ds->buf; } else { for(p2 = p; *p2 != '/'; p2--) ; *p2++ = 0; ds->netdir = ds->buf; ds->proto = p2; } *p = 0; ds->host = p + 1; } ds->service = strchr(ds->host, '!'); if(ds->service) *ds->service++ = 0; if(*ds->host == '$') expand_meta(ds); } static void expand_meta(DS *ds) { static Ndb *db; Ndbs s; char *sys, *smtpserver; /* can't ask cs, so query database directly. */ sys = sysname(); if(db == nil) db = ndbopen(0); smtpserver = ndbgetvalue(db, &s, "sys", sys, "smtp", nil); snprint(ds->host, 128, "%s", smtpserver); }