diff options
| -rw-r--r-- | libc/inet/resolv.c | 95 |
1 files changed, 49 insertions, 46 deletions
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index 8781196c6..07dff18dd 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -456,7 +456,8 @@ extern int __read_etc_hosts_r(parser_t *parser, extern int __dns_lookup(const char *name, int type, unsigned char **outpacket, - struct resolv_answer *a) attribute_hidden; + struct resolv_answer *a, + int *h_errnop) attribute_hidden; extern int __encode_dotted(const char *dotted, unsigned char *dest, int maxlen) attribute_hidden; @@ -1233,7 +1234,8 @@ static int __decode_answer(const unsigned char *message, /* packet */ int attribute_hidden __dns_lookup(const char *name, int type, unsigned char **outpacket, - struct resolv_answer *a) + struct resolv_answer *a, + int *h_errnop) { /* Protected by __resolv_lock: */ static int last_ns_num = 0; @@ -1265,11 +1267,15 @@ int attribute_hidden __dns_lookup(const char *name, fd = -1; lookup = NULL; name_len = strlen(name); - if ((unsigned)name_len >= MAXDNAME - MAXLEN_searchdomain - 2) - goto fail; /* paranoia */ + if ((unsigned)name_len >= MAXDNAME - MAXLEN_searchdomain - 2) { + *h_errnop = NO_RECOVERY; + goto fail1; /* paranoia */ + } lookup = malloc(name_len + 1/*for '.'*/ + MAXLEN_searchdomain + 1); - if (!packet || !lookup || !name[0]) - goto fail; + if (!packet || !lookup || !name[0]) { + *h_errnop = NO_RECOVERY; + goto fail1; + } ends_with_dot = (name[name_len - 1] == '.'); /* no strcpy! paranoia, user might change name[] under us */ memcpy(lookup, name, name_len); @@ -1337,8 +1343,10 @@ int attribute_hidden __dns_lookup(const char *name, h.rd = 1; DPRINTF("encoding header\n", h.rd); i = __encode_header(&h, packet, PACKETSZ); - if (i < 0) - goto fail; + if (i < 0) { + *h_errnop = NO_RECOVERY; + goto fail1; + } /* encode question */ DPRINTF("lookup name: %s\n", lookup); @@ -1346,8 +1354,10 @@ int attribute_hidden __dns_lookup(const char *name, q.qtype = type; q.qclass = C_IN; /* CLASS_IN */ j = __encode_question(&q, packet+i, PACKETSZ-i); - if (j < 0) - goto fail; + if (j < 0) { + *h_errnop = NO_RECOVERY; + goto fail1; + } packet_len = i + j; /* send packet */ @@ -1473,7 +1483,7 @@ int attribute_hidden __dns_lookup(const char *name, /* no more search domains to try */ } /* dont loop, this is "no such host" situation */ - h_errno = HOST_NOT_FOUND; + *h_errnop = HOST_NOT_FOUND; goto fail1; } /* Insert other non-fatal errors here, which do not warrant @@ -1485,7 +1495,7 @@ int attribute_hidden __dns_lookup(const char *name, /* Code below won't work correctly with h.ancount == 0, so... */ if (h.ancount <= 0) { - h_errno = NO_DATA; /* [is this correct code to check for?] */ + *h_errnop = NO_DATA; /* [is this correct code to check for?] */ goto fail1; } pos = HFIXEDSZ; @@ -1564,8 +1574,7 @@ int attribute_hidden __dns_lookup(const char *name, variant = -1; } while (retries_left > 0); - fail: - h_errno = NETDB_INTERNAL; + *h_errnop = TRY_AGAIN; fail1: if (fd != -1) close(fd); @@ -2106,9 +2115,8 @@ int gethostbyname_r(const char *name, * we'll need space of one in_addr + two addr_list[] elems */ a.buflen = buflen - ((sizeof(addr_list[0]) * 2 + sizeof(struct in_addr))); a.add_count = 0; - packet_len = __dns_lookup(name, T_A, &packet, &a); + packet_len = __dns_lookup(name, T_A, &packet, &a, h_errnop); if (packet_len < 0) { - *h_errnop = HOST_NOT_FOUND; DPRINTF("__dns_lookup returned < 0\n"); return TRY_AGAIN; } @@ -2292,9 +2300,8 @@ int gethostbyname2_r(const char *name, int packet_len; /* Hmm why we memset(a) to zeros only once? */ - packet_len = __dns_lookup(buf, T_AAAA, &packet, &a); + packet_len = __dns_lookup(buf, T_AAAA, &packet, &a, h_errnop); if (packet_len < 0) { - *h_errnop = HOST_NOT_FOUND; return TRY_AGAIN; } strncpy(buf, a.dotted, buflen); @@ -2450,9 +2457,8 @@ int gethostbyaddr_r(const void *addr, socklen_t addrlen, memset(&a, '\0', sizeof(a)); for (;;) { /* Hmm why we memset(a) to zeros only once? */ - packet_len = __dns_lookup(buf, T_PTR, &packet, &a); + packet_len = __dns_lookup(buf, T_PTR, &packet, &a, h_errnop); if (packet_len < 0) { - *h_errnop = HOST_NOT_FOUND; return TRY_AGAIN; } @@ -3091,7 +3097,7 @@ int res_query(const char *dname, int class, int type, } memset(&a, '\0', sizeof(a)); - i = __dns_lookup(dname, type, &packet, &a); + i = __dns_lookup(dname, type, &packet, &a, &h_errno); if (i < 0) { if (!h_errno) /* TODO: can this ever happen? */ @@ -3117,14 +3123,13 @@ libc_hidden_def(res_query) */ #define __TRAILING_DOT (1<<0) #define __GOT_NODATA (1<<1) -#define __GOT_SERVFAIL (1<<2) +#define __GOT_TRYAGAIN (1<<2) #define __TRIED_AS_IS (1<<3) int res_search(const char *name, int class, int type, u_char *answer, int anslen) { const char *cp; char **domain; - HEADER *hp = (HEADER *)(void *)answer; unsigned dots; unsigned state; int ret, saved_herrno; @@ -3189,19 +3194,9 @@ int res_search(const char *name, int class, int type, u_char *answer, if (ret > 0) return ret; - /* - * If no server present, give up. - * If name isn't found in this domain, - * keep trying higher domains in the search list - * (if that's enabled). - * On a NO_DATA error, keep trying, otherwise - * a wildcard entry of another type could keep us - * from finding this entry higher in the domain. - * If we get some other error (negative answer or - * server failure), then stop searching up, - * but try the input name below in case it's - * fully-qualified. - */ + /* our resolver refused to talk to us - + * no sense to retry, as the retry would likely + * fail too */ if (errno == ECONNREFUSED) { h_errno = TRY_AGAIN; return -1; @@ -3209,21 +3204,29 @@ int res_search(const char *name, int class, int type, u_char *answer, switch (h_errno) { case NO_DATA: + /* Keep trying, otherwise a + * wildcard entry of another type + * could keep us from finding this + * entry from higher in the domain + * search. */ state |= __GOT_NODATA; - /* FALLTHROUGH */ + break; case HOST_NOT_FOUND: - /* keep trying */ + /* Not found - keep trying higher + * domains in the search list. */ break; case TRY_AGAIN: - if (hp->rcode == SERVFAIL) { - /* try next search element, if any */ - state |= __GOT_SERVFAIL; - break; - } - /* FALLTHROUGH */ + /* Server error or timeout. Could + * be caused by a problem in servers + * our resolver queried. Keep trying + * search, but remember that there + * was a temporary problem. */ + state |= __GOT_TRYAGAIN; + break; default: /* anything else implies that we're done */ done = 1; + break; } /* * if we got here for some reason other than DNSRCH, @@ -3257,13 +3260,13 @@ int res_search(const char *name, int class, int type, u_char *answer, h_errno = saved_herrno; else if (state & __GOT_NODATA) h_errno = NO_DATA; - else if (state & __GOT_SERVFAIL) + else if (state & __GOT_TRYAGAIN) h_errno = TRY_AGAIN; return -1; } #undef __TRAILING_DOT #undef __GOT_NODATA -#undef __GOT_SERVFAIL +#undef __GOT_TRYAGAIN #undef __TRIED_AS_IS /* * Perform a call on res_query on the concatenation of name and domain, |