X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=checkalias.c;h=2e50ea09222d3cd61b469b953839e41a6665c027;hb=6463caede766da351104ef421c0bcea52d4c4ba7;hp=413b40475a25aa738c05ee9990b76603ee394313;hpb=66965e0e36694b9bec880073b3e4e02a70988355;p=~andy%2Ffetchmail diff --git a/checkalias.c b/checkalias.c index 413b4047..2e50ea09 100644 --- a/checkalias.c +++ b/checkalias.c @@ -1,73 +1,248 @@ +/* + * checkalias.c -- check to see if two hostnames or IP addresses are equivalent + * + * Copyright 1997 by Eric S. Raymond + * For license terms, see the file COPYING in this directory. + */ +#include "config.h" +#include #include #include #include +#ifdef HAVE_NET_SOCKET_H +#include +#else #include +#endif #include +#ifdef HAVE_ARPA_INET_H #include +#endif #include +#include "i18n.h" +#include "mx.h" #include "fetchmail.h" +#include "getaddrinfo.h" + +#define MX_RETRIES 3 + +typedef unsigned char address_t[sizeof (struct in_addr)]; + +#ifdef HAVE_RES_SEARCH +static int getaddresses(struct addrinfo **result, const char *name) +{ + struct addrinfo hints; + + memset(&hints, 0, sizeof(hints)); + hints.ai_socktype=SOCK_STREAM; + hints.ai_protocol=PF_UNSPEC; + hints.ai_family=AF_UNSPEC; + return fm_getaddrinfo(name, NULL, &hints, result); +} + +/* XXX FIXME: doesn't detect if an IPv6-mapped IPv4 address + * matches a real IPv4 address */ +static int compareaddr(const struct addrinfo *a1, const struct addrinfo *a2) +{ + if (a1->ai_family != a2->ai_family) return FALSE; + if (a1->ai_addrlen != a2->ai_addrlen) return FALSE; + return (!memcmp(a1->ai_addr, a2->ai_addr, a1->ai_addrlen)); +} - -int is_ip_alias(const char *name1,const char *name2) -/* Given two hostnames as arguments, returns TRUE if they +static int is_ip_alias(const char *name1,const char *name2) +/* + * Given two hostnames as arguments, returns TRUE if they * have at least one IP address in common. - * It is meant to be called by the is_host_alias() function in driver.c * No check is done on errors returned by gethostbyname, * the calling function does them. */ - { - - typedef unsigned char address_t[sizeof (struct in_addr)]; - typedef struct _address_e { struct _address_e *next; - address_t address; - } address_e; - - address_e *host_a_addr, *host_b_addr,*dummy_addr; - - int i; - - struct hostent *hp; - - char **p; - - hp = gethostbyname(name1); - - dummy_addr = (address_e *)NULL; - - for (i=0,p = hp->h_addr_list; *p != 0; i++,p++) { - struct in_addr in; - (void) memcpy(&in.s_addr, *p, sizeof (in.s_addr)); - host_a_addr = (address_e *)xmalloc(sizeof( address_e)); - memset (host_a_addr,0, sizeof (address_e)); - host_a_addr->next = dummy_addr; - (void) memcpy(&host_a_addr->address, *p, sizeof (in.s_addr)); - dummy_addr = host_a_addr; - } - - - hp = gethostbyname(name2); - - dummy_addr = (address_e *)NULL; - - for (i=0,p = hp->h_addr_list; *p != 0; i++,p++) { - struct in_addr in; - (void) memcpy(&in.s_addr, *p, sizeof (in.s_addr)); - host_b_addr = (address_e *)xmalloc(sizeof( address_e)); - memset (host_b_addr,0, sizeof (address_e)); - host_b_addr->next = dummy_addr; - (void) memcpy(&host_b_addr->address, *p, sizeof (in.s_addr)); - dummy_addr = host_b_addr; - } - - while (host_a_addr) { - while (host_b_addr) { - - if (!memcmp(host_b_addr->address,host_a_addr->address, sizeof (address_t))) return (TRUE); - - host_b_addr = host_b_addr->next; - } - host_a_addr = host_a_addr->next; +{ + int rc = FALSE; + + struct addrinfo *res1 = NULL, *res2 = NULL, *ii, *ij; + + if (getaddresses(&res1, name1)) + goto found; + + if (getaddresses(&res2, name2)) + goto found; + + for (ii = res1 ; ii ; ii = ii -> ai_next) { + for (ij = res2 ; ij ; ij = ij -> ai_next) { + if (compareaddr(ii, ij)) { + rc = TRUE; + goto found; + } } -return (FALSE); + } + +found: + if (res2) + fm_freeaddrinfo(res2); + if (res1) + fm_freeaddrinfo(res1); + return rc; +} +#endif + +int is_host_alias(const char *name, struct query *ctl, struct addrinfo **res) +/* determine whether name is a DNS alias of the mailserver for this query */ +{ +#ifdef HAVE_RES_SEARCH + struct mxentry *mxp, *mxrecords; + int e; + struct addrinfo hints, *res_st; +#endif + struct idlist *idl; + size_t namelen; + + struct hostdata *lead_server = + ctl->server.lead_server ? ctl->server.lead_server : &ctl->server; + + /* + * The first two checks are optimizations that will catch a good + * many cases. + * + * (1) check against the `true name' deduced from the poll label + * and the via option (if present) at the beginning of the poll cycle. + * Odds are good this will either be the mailserver's FQDN or a suffix of + * it with the mailserver's domain's default host name omitted. + * + * (2) Then check the rest of the `also known as' + * cache accumulated by previous DNS checks. This cache is primed + * by the aka list option. + * + * Any of these on a mail address is definitive. Only if the + * name doesn't match any is it time to call the bind library. + * If this happens odds are good we're looking at an MX name. + */ + if (strcasecmp(lead_server->truename, name) == 0) + return(TRUE); + else if (str_in_list(&lead_server->akalist, name, TRUE)) + return(TRUE); + + /* + * Now check for a suffix match on the akalist. The theory here is + * that if the user says `aka netaxs.com', we actually want to match + * foo.netaxs.com and bar.netaxs.com. + */ + namelen = strlen(name); + for (idl = lead_server->akalist; idl; idl = idl->next) + { + const char *ep; + + /* + * Test is >= here because str_in_list() should have caught the + * equal-length case above. Doing it this way guarantees that + * ep[-1] is a valid reference. + */ + if (strlen(idl->id) >= namelen) + continue; + ep = name + (namelen - strlen(idl->id)); + /* a suffix led by . must match */ + if (ep[-1] == '.' && !strcasecmp(ep, idl->id)) + return(TRUE); + } + + if (!ctl->server.dns) + return(FALSE); +#ifndef HAVE_RES_SEARCH + (void)res; + return(FALSE); +#else + /* + * The only code that calls the BIND library is here and in the + * start-of-run probe with gethostbyname(3) under ETRN/Kerberos. + * + * We know DNS service was up at the beginning of the run. + * If it's down, our nameserver has crashed. We don't want to try + * delivering the current message or anything else from the + * current server until it's back up. + */ + memset(&hints, 0, sizeof hints); + hints.ai_family=AF_UNSPEC; + hints.ai_protocol=PF_UNSPEC; + hints.ai_socktype=SOCK_STREAM; + hints.ai_flags=AI_CANONNAME; + + e = fm_getaddrinfo(name, NULL, &hints, res); + if (e == 0) + { + int rr = (strcasecmp(ctl->server.truename, (*res)->ai_canonname) == 0); + fm_freeaddrinfo(*res); *res = NULL; + if (rr) + goto match; + else if (ctl->server.checkalias && 0 == fm_getaddrinfo(ctl->server.truename, NULL, &hints, &res_st)) + { + fm_freeaddrinfo(res_st); + if (outlevel >= O_DEBUG) + report(stdout, GT_("Checking if %s is really the same node as %s\n"),ctl->server.truename,name); + if (is_ip_alias(ctl->server.truename,name) == TRUE) + { + if (outlevel >= O_DEBUG) + report(stdout, GT_("Yes, their IP addresses match\n")); + goto match; + } + if (outlevel >= O_DEBUG) + report(stdout, GT_("No, their IP addresses don't match\n")); + return(FALSE); + } else { + return(FALSE); + } + } + else + switch (e) + { + case EAI_NONAME: /* specified host is unknown */ + break; + + default: + if (outlevel != O_SILENT) + report_complete(stdout, "\n"); /* terminate the progress message */ + report(stderr, + GT_("nameserver failure while looking for '%s' during poll of %s: %s\n"), + name, ctl->server.pollname, gai_strerror(e)); + ctl->errcount++; + break; + } + + /* + * We're only here if DNS was OK but the gethostbyname() failed + * with a HOST_NOT_FOUND or NO_ADDRESS error. + * Search for a name match on MX records pointing to the server. + */ + h_errno = 0; + if ((mxrecords = getmxrecords(name)) == (struct mxentry *)NULL) + { + switch (h_errno) + { + case HOST_NOT_FOUND: /* specified host is unknown */ +#ifdef NO_ADDRESS + case NO_ADDRESS: /* valid, but does not have an IP address */ + return(FALSE); +#endif + case NO_RECOVERY: /* non-recoverable name server error */ + case TRY_AGAIN: /* temporary error on authoritative server */ + default: + report(stderr, + GT_("nameserver failure while looking for `%s' during poll of %s.\n"), + name, ctl->server.pollname); + ctl->errcount++; + break; + } + } else { + for (mxp = mxrecords; mxp->name; mxp++) + if (strcasecmp(ctl->server.truename, mxp->name) == 0 + || is_ip_alias(ctl->server.truename, mxp->name) == TRUE) + goto match; + return(FALSE); + match:; + } + + /* add this name to relevant server's `also known as' list */ + save_str(&lead_server->akalist, name, 0); + return(TRUE); +#endif /* HAVE_RES_SEARCH */ } +/* checkalias.c ends here */