diff options
| -rw-r--r-- | libc/inet/resolv.c | 226 |
1 files changed, 136 insertions, 90 deletions
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index 044059d7d..7ef2fba45 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -762,6 +762,10 @@ int attribute_hidden __dns_lookup(const char *name, int type, int nscount, char **nsip, unsigned char **outpacket, struct resolv_answer *a) +//FIXME: nscount/nsip are *always* taken from __nameservers and __nameserver[] +//globals. Locking is busted: __nameserver[] can be freed under us. +//Fix it by eliminating these params and accessing __nameserver(s) +//only under lock inside this routine. { int i, j, len, fd, pos, rc; #ifdef USE_SELECT @@ -2084,20 +2088,44 @@ libc_hidden_def(getnameinfo) #ifdef L_gethostbyname_r +/* Bug 671 says: + * "uClibc resolver's gethostbyname does not return the requested name + * as an alias, but instead returns the canonical name. glibc's + * gethostbyname has a similar bug where it returns the requested name + * with the search domain name appended (to make a FQDN) as an alias, + * but not the original name itself. Both contradict POSIX, which says + * that the name argument passed to gethostbyname must be in the alias list" + * This is fixed now, and we differ from glibc: + * + * $ ./gethostbyname_uclibc wer.google.com + * h_name:'c13-ss-2-lb.cnet.com' + * h_length:4 + * h_addrtype:2 AF_INET + * alias:'wer.google.com' <=== + * addr: 0x4174efd8 '216.239.116.65' + * + * $ ./gethostbyname_glibc wer.google.com + * h_name:'c13-ss-2-lb.cnet.com' + * h_length:4 + * h_addrtype:2 AF_INET + * alias:'wer.google.com.com' <=== + * addr:'216.239.116.65' + * + * When examples were run, /etc/resolv.conf contained "search com" line. + */ int gethostbyname_r(const char * name, - struct hostent * result_buf, - char * buf, size_t buflen, - struct hostent ** result, - int * h_errnop) + struct hostent * result_buf, + char * buf, + size_t buflen, + struct hostent ** result, + int * h_errnop) { - struct in_addr *in; struct in_addr **addr_list; char **alias; + char *alias0; unsigned char *packet; struct resolv_answer a; int i; - int __nameserversXX; - char ** __nameserverXX; *result = NULL; if (!name) @@ -2128,122 +2156,140 @@ int gethostbyname_r(const char * name, DPRINTF("Nothing found in /etc/hosts\n"); - /* make sure user char * is aligned */ - i = ALIGN_BUFFER_OFFSET(buf); - if (unlikely(i)) { - if (buflen < i) - return ERANGE; - buf += i; - buflen -= i; - } - *h_errnop = NETDB_INTERNAL; - if (buflen < sizeof(*in)) - return ERANGE; - in = (struct in_addr*)buf; - buf += sizeof(*in); - buflen -= sizeof(*in); - if (buflen < sizeof(*addr_list)*2) + /* prepare future h_aliases[0] */ + i = strlen(name) + 1; + if ((ssize_t)buflen <= i) return ERANGE; - addr_list = (struct in_addr**)buf; - buf += sizeof(*addr_list)*2; - buflen -= sizeof(*addr_list)*2; + strcpy(buf, name); + alias0 = buf; + buf += i; + buflen -= i; - addr_list[0] = in; - addr_list[1] = 0; + /* make sure pointer is aligned */ + i = ALIGN_BUFFER_OFFSET(buf); + buf += i; + buflen -= i; - if (buflen < sizeof(char *)*ALIAS_DIM) - return ERANGE; alias = (char **)buf; - buf += sizeof(char **)*ALIAS_DIM; - buflen -= sizeof(char **)*ALIAS_DIM; + buf += sizeof(alias[0]) * 2; + buflen -= sizeof(alias[0]) * 2; - if (buflen < 256) + addr_list = (struct in_addr **)buf; + + /* do not use *buf or buflen before this verification! */ + /* buflen may be < 0, must do signed compare */ + if ((ssize_t)buflen < 256) return ERANGE; - strncpy(buf, name, buflen); - alias[0] = buf; + /* we store only one "alias" - the name itself */ +#ifdef __UCLIBC_MJN3_ONLY__ +#warning TODO -- generate the full list +#endif + alias[0] = alias0; alias[1] = NULL; - /* First check if this is already an address */ - if (inet_aton(name, in)) { - result_buf->h_name = buf; - result_buf->h_addrtype = AF_INET; - result_buf->h_length = sizeof(*in); - result_buf->h_addr_list = (char **) addr_list; - result_buf->h_aliases = alias; - *result = result_buf; - *h_errnop = NETDB_SUCCESS; - return NETDB_SUCCESS; + /* maybe it is already an address? */ + { + struct in_addr *in = (struct in_addr *)(buf + sizeof(addr_list[0]) * 2); + if (inet_aton(name, in)) { + addr_list[0] = in; + addr_list[1] = NULL; + result_buf->h_name = alias0; + result_buf->h_aliases = alias; + result_buf->h_addrtype = AF_INET; + result_buf->h_length = sizeof(struct in_addr); + result_buf->h_addr_list = (char **) addr_list; + *result = result_buf; + *h_errnop = NETDB_SUCCESS; + return NETDB_SUCCESS; + } } + /* talk to DNS servers */ __open_nameservers(); - - /*for (;;)*/ { -//FIXME: why was it a loop? It never loops... + { + int __nameserversXX; + char ** __nameserverXX; __UCLIBC_MUTEX_LOCK(__resolv_lock); __nameserversXX = __nameservers; __nameserverXX = __nameserver; __UCLIBC_MUTEX_UNLOCK(__resolv_lock); a.buf = buf; - a.buflen = buflen; + /* take into account that at least one address will be there, + * 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; i = __dns_lookup(name, T_A, __nameserversXX, __nameserverXX, &packet, &a); - if (i < 0) { *h_errnop = HOST_NOT_FOUND; - DPRINTF("__dns_lookup\n"); + DPRINTF("__dns_lookup returned < 0\n"); return TRY_AGAIN; } + } - if ((a.rdlength + sizeof(struct in_addr*)) * a.add_count + 256 > buflen) { - free(a.dotted); - free(packet); - *h_errnop = NETDB_INTERNAL; + if (a.atype == T_A) { /* ADDRESS */ + /* we need space for addr_list[] and one IPv4 address */ + /* + 1 accounting for 1st addr (it's in a.rdata), + * another + 1 for NULL in last addr_list[]: */ + int need_bytes = sizeof(addr_list[0]) * (a.add_count + 1 + 1) + /* for 1st addr (it's in a.rdata): */ + + sizeof(struct in_addr); + /* how many bytes will 2nd and following addresses take? */ + int ips_len = a.add_count * a.rdlength; + + buflen -= (need_bytes + ips_len); + if ((ssize_t)buflen < 0) { DPRINTF("buffer too small for all addresses\n"); - return ERANGE; + /* *h_errnop = NETDB_INTERNAL; - already is */ + i = ERANGE; + goto free_and_ret; } - if (a.add_count > 0) { - memmove(buf - sizeof(struct in_addr*)*2, buf, a.add_count * a.rdlength); - addr_list = (struct in_addr**)(buf + a.add_count * a.rdlength); - addr_list[0] = in; - for (i = a.add_count - 1; i >= 0; --i) - addr_list[i+1] = (struct in_addr*)(buf - sizeof(struct in_addr*)*2 + a.rdlength * i); - addr_list[a.add_count + 1] = 0; - buflen -= (((char*)&(addr_list[a.add_count + 2])) - buf); - buf = (char*)&addr_list[a.add_count + 2]; - } + /* if there are additional addresses in buf, + * move them forward so that they are not destroyed */ + DPRINTF("a.add_count:%d a.rdlength:%d a.rdata:%p\n", a.add_count, a.rdlength, a.rdata); + memmove(buf + need_bytes, buf, ips_len); - strncpy(buf, a.dotted, buflen); - free(a.dotted); + /* 1st address is in a.rdata, insert it */ + buf += need_bytes - sizeof(struct in_addr); + memcpy(buf, a.rdata, sizeof(struct in_addr)); - if (a.atype == T_A) { /* ADDRESS */ - memcpy(in, a.rdata, sizeof(*in)); - result_buf->h_name = buf; - result_buf->h_addrtype = AF_INET; - result_buf->h_length = sizeof(*in); - result_buf->h_addr_list = (char **) addr_list; -#ifdef __UCLIBC_MJN3_ONLY__ -#warning TODO -- generate the full list -#endif - result_buf->h_aliases = alias; /* TODO: generate the full list */ - free(packet); - /*was: break;*/ - *result = result_buf; - *h_errnop = NETDB_SUCCESS; - return NETDB_SUCCESS; + /* fill addr_list[] */ + for (i = 0; i <= a.add_count; i++) { + addr_list[i] = (struct in_addr*)buf; + buf += sizeof(struct in_addr); } - free(packet); - *h_errnop = HOST_NOT_FOUND; - return TRY_AGAIN; + addr_list[i] = NULL; + + /* if we have enough space, we can report "better" name + * (it may contain search domains attached by __dns_lookup, + * or CNAME of the host if it is different from the name + * we used to find it) */ + if (a.dotted && buflen > strlen(a.dotted)) { + strcpy(buf, a.dotted); + alias0 = buf; + } + + result_buf->h_name = alias0; + result_buf->h_aliases = alias; + result_buf->h_addrtype = AF_INET; + result_buf->h_length = sizeof(struct in_addr); + result_buf->h_addr_list = (char **) addr_list; + *result = result_buf; + *h_errnop = NETDB_SUCCESS; + i = NETDB_SUCCESS; + goto free_and_ret; } -/* - *result = result_buf; - *h_errnop = NETDB_SUCCESS; - return NETDB_SUCCESS; -*/ + + *h_errnop = HOST_NOT_FOUND; + i = TRY_AGAIN; + + free_and_ret: + free(a.dotted); + free(packet); + return i; } libc_hidden_def(gethostbyname_r) #endif |