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2018-09-02fix stack-based oob memory clobber in resolver's result sortingRich Felker1-1/+1
commit 4f35eb7591031a1e5ef9828f9304361f282f28b9 introduced this bug. it is not present in any released versions. inadvertent use of the & operator on an array into which we're indexing produced arithmetic on the wrong-type pointer, with undefined behavior.
2018-07-14implement getaddrinfo's AI_ADDRCONFIG flagRich Felker1-0/+39
this flag is notoriously under-/mis-specified, and in the past it was implemented as a nop, essentially considering the absence of a loopback interface with 127.0.0.1 and ::1 addresses an unsupported configuration. however, common real-world container environments omit IPv6 support (even for the network-namespaced loopback interface), and some kernels omit IPv6 support entirely. future systems on the other hand might omit IPv4 entirely. treat these as supported configurations and suppress results of the unconfigured/unsupported address families when AI_ADDRCONFIG is requested. use routability of the loopback address to make the determination; unlike other implementations, we do not exclude loopback from the "an address is configured" condition, since there is no basis in the specification for such exclusion. obtaining a result with AI_ADDRCONFIG does not imply routability of the result, and applications must still be able to cope with unroutable results even if they pass AI_ADDRCONFIG.
2018-07-11resolver: don't depend on v4mapped ipv6 to probe routability of v4 addrsRich Felker1-15/+32
to produce sorted results roughly corresponding to RFC 3484/6724, __lookup_name computes routability and choice of source address via dummy UDP connect operations (which do not produce any packets). since at the logical level, the properties fed into the sort key are computed on ipv6 addresses, the code was written to use the v4mapped ipv6 form of ipv4 addresses and share a common code path for them all. however, on kernels where ipv6 support has been completely omitted, this causes ipv4 to appear equally unroutable as ipv6, thereby putting unreachable ipv6 addresses before ipv4 addresses in the results. instead, use only ipv4 sockets to compute routability for ipv4 addresses. some gratuitous conversion back and forth is left so that the logic is not affected by these changes. it may be possible to simplify the ipv4 case considerably, thereby reducing code size and complexity.
2018-06-26inet_ntop: do not compress single zeros in IPv6Arthur Jones1-1/+1
maintainer's note: this change is for conformance with RFC 5952, 4.2.2, which explicitly forbids use of :: to shorten a single 16-bit 0 field when producing the canonical text representation for an IPv6 address. fixes a test failure reported by Philip Homburg, who also submitted a patch, but this fix is simpler and should produce smaller code.
2018-06-26resolver: omit final dot (root/suppress-search) in canonical nameRich Felker1-0/+4
if a final dot was included in the queried host name to anchor it to the dns root/suppress search domains, and the result was not a CNAME, the returned canonical name included the final dot. this was not consistent with other implementations, confused some applications, and does not seem desirable. POSIX specifies returning a pointer to, or to a copy of, the input nodename, when the canonical name is not available, but does not attempt to specify what constitutes "not available". in the case of search, we already have an implementation-defined "availability" of a canonical name as the fully-qualified name resulting from search, so defining it similarly in the no-search case seems reasonable in addition to being consistent with other implementations. as a bonus, fix the case where more than one trailing dot is included, since otherwise the changes made here would wrongly cause lookups with two trailing dots to succeed. previously this case resulted in malformed dns queries and produced EAI_AGAIN after a timeout. now it fails immediately with EAI_NONAME.
2017-11-09fix getaddrinfo error code for non-numeric service with AI_NUMERICSERVA. Wilcox1-1/+1
If AI_NUMERICSERV is specified and a numeric service was not provided, POSIX mandates getaddrinfo return EAI_NONAME. EAI_SERVICE is only for services that cannot be used on the specified socket type.
2017-10-18in dns parsing callback, enforce MAXADDRS to preclude overflowRich Felker1-0/+1
MAXADDRS was chosen not to need enforcement, but the logic used to compute it assumes the answers received match the RR types of the queries. specifically, it assumes that only one replu contains A record answers. if the replies to both the A and the AAAA query have their answer sections filled with A records, MAXADDRS can be exceeded and clobber the stack of the calling function. this bug was found and reported by Felix Wilhelm.
2017-09-06don't treat numeric port strings as servent records in getservby*()Rich Felker2-0/+10
some applications use getservbyport to find port numbers that are not assigned to a service; if getservbyport always succeeds with a numeric string as the result, they fail to find any available ports. POSIX doesn't seem to mandate the behavior one way or another. it specifies an abstract service database, which an implementation could define to include numeric port strings, but it makes more sense to align behavior with traditional implementations. based on patch by A. Wilcox. the original patch only changed getservbyport[_r]. to maintain a consistent view of the "service database", I have also modified getservbyname[_r] to exclude numeric port strings.
2017-04-21fix regression in support for resolv.conf attempts optionRich Felker1-2/+2
commit d6cb08bcaca4ff1f921375510ca72bccea969c75 moved the code and introduced an incorrect string offset for the new parsing, probably due to a copy-and-paste error. patch by Stefan Sedich.
2017-04-11fix read past end of buffer in getaddrinfo backendRich Felker1-2/+2
due to testing buf[i].family==AF_INET before checking i==cnt, it was possible to read past the end of the array, or past the valid part. in practice, without active bounds/indeterminate-value checking by the compiler, the worst that happened was failure to return early and optimize out the sorting that's unneeded for v4-only results. returning on i==cnt-1 rather than i==cnt would be an alternate fix, but the approach this patch takes is more idiomatic and less error-prone. patch by Timo Teräs.
2017-03-14fix possible fd leak, unrestored cancellation state on dns socket failRich Felker1-1/+5
2016-09-24fix getservby*_r result pointer value on errorDaniel Sabogal2-0/+3
this is a clone of the fix to the gethostby*_r functions in commit fe82bb9b921be34370e6b71a1c6f062c20999ae0. the man pages document that the getservby*_r functions set this pointer to NULL if there was an error or if no record was found.
2016-09-24remove dead case in gethostbyname2_rDaniel Sabogal1-2/+0
this case statement was accidently left behind when this function was refactored in commit e8f39ca4898237cf71657500f0b11534c47a0521.
2016-09-16fix if_indextoname error caseDaniel Sabogal1-1/+6
posix requires errno to be set to ENXIO if the interface does not exist. linux returns ENODEV instead so we handle this.
2016-07-06remove obsolete and unused gethostbyaddr implementationRich Felker1-52/+0
this code was already under #if 0, but could be confusing if a reader didn't notice that, and it's almost surely full of bugs and/or inconsistencies with the current code that uses the gethostbyname2_r backend.
2016-06-29refactor name_from_dns in hostname lookup backendNatanael Copa1-14/+13
loop over an address family / resource record mapping to avoid repetitive code.
2016-06-29in performing dns lookups, check result from res_mkqueryNatanael Copa1-0/+4
don't send a query that may be malformed.
2016-06-27fix misaligned address buffers in gethostbyname[2][_r] resultsRich Felker1-7/+7
mistakenly ordering strings before addresses in the result buffer broke the alignment that the preceding code had set up.
2016-05-04fix incorrect protocol name and number for egpAndrew Kelley1-1/+1
previously if you called getprotobyname("egp") you would get NULL because \008 is invalid octal and so the protocol id was interpreted as 0 and name as "8egp".
2016-04-18remove dead store in res_msendPetr Vaněk1-1/+0
The variable nss is set to zero in following line.
2016-03-24fix gethostbyaddr_r to fill struct hostent.h_length as appropriateTimo Teräs1-0/+1
2016-03-02handle non-matching address family entries in hosts fileRich Felker1-3/+11
name_from_hosts failed to account for the possibility of an address family error from name_from_numeric, wrongly counting such a return as success and using the uninitialized address data as part of the results passed up to the caller. non-matching address family entries cannot simply be ignored or results would be inconsistent with respect to whether AF_UNSPEC or a specific address family is queried. instead, record that a non-matching entry was seen, and fail the lookup with EAI_NONAME of no matching-family entries are found.
2016-01-28reuse parsed resolv.conf in dns core to avoid re-reading/re-parsingRich Felker2-16/+22
2016-01-28fix uninitialized variable in new resolv.conf parserRich Felker1-1/+1
2016-01-28add support for search domains to dns resolverRich Felker1-1/+41
search is only performed if the search or domain keyword is used in resolv.conf and the queried name has fewer than ndots dots. there is no default domain and names with >=ndots dots are never subjected to search; failure in the root scope is final. the (non-POSIX) res_search API presently does not honor search. this may be added at some point in the future if needed. resolv.conf is now parsed twice, at two different layers of the code involved. this will be fixed in a subsequent patch.
2016-01-28fix handling of dns response codesRich Felker1-1/+2
rcode of 3 (NxDomain) was treated as a hard EAI_NONAME failure, but it should instead return 0 (no results) so the caller can continue searching. this will be important for adding search domain support. the top-level caller will automatically return EAI_NONAME if there are zero results at the end. also, the case where rcode is 0 (success) but there are no results was not handled. this happens when the domain exists but there are no A or AAAA records for it. in this case a hard EAI_NONAME should be imposed to inhibit further search, since the name was defined and just does not have any address associated with it. previously a misleading hard failure of EAI_FAIL was reported.
2016-01-28fix logic for matching search/domain keywords in resolv.confRich Felker1-1/+1
2016-01-28factor resolv.conf parsing out of res_msend to its own fileRich Felker3-60/+126
this change is made in preparation for adding search domains, for which higher-level code will need to parse resolv.conf. simply parsing it twice for each lookup would be one reasonable option, but the existing parser code was buggy anyway, which suggested to me that it's a bad idea to have two variants of this code in two different places. the old code in res_msend potentially misinterpreted overly long lines in resolv.conf, and stopped parsing after it found 3 nameservers, even if there were relevant options left to be parsed later in the file.
2016-01-17fix if_nametoindex return value when socket open failsRon Yorston1-1/+1
The return value of if_nametoindex is unsigned; it should return 0 on error.
2016-01-06add missing protocols to protoent lookup functionsTimo Teräs1-1/+16
2015-11-30properly handle point-to-point interfaces in getifaddrs()Jo-Philipp Wich1-3/+16
With point-to-point interfaces, the IFA_ADDRESS netlink attribute contains the peer address while an extra attribute IFA_LOCAL carries the actual local interface address. Both the glibc and uclibc implementations of getifaddrs() handle this case by moving the ifa_addr contents to the broadcast/remote address union and overwriting ifa_addr upon receipt of an IFA_LOCAL attribute. This patch adds the same special treatment logic of IFA_LOCAL to musl's implementation of getifaddrs() in order to align its behaviour with that of uclibc and glibc. Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>
2015-10-26getnameinfo: make size check not fail for bigger sizesHauke Mehrtens1-2/+2
getnameinfo() compares the size of the given struct sockaddr with sizeof(struct sockaddr_in) and sizeof(struct sockaddr_in6) depending on the net family. When you add a sockaddr of size sizeof(struct sockaddr_storage) this function will fail because the size of the sockaddr is too big. Change the check that it only fails if the size is too small, but make it work when it is too big for example when someone calls this function with a struct sockaddr_storage and its size. This fixes a problem with IoTivity 1.0.0 and musl. glibc and bionic are only failing if it is smaller, net/freebsd implemented the != check. Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
2015-10-26safely handle failure to open hosts, services, resolv.conf filesRich Felker3-4/+29
previously, transient failures like fd exhaustion or other resource-related errors were treated the same as non-existence of these files, leading to fallbacks or false-negative results. in particular: - failure to open hosts resulted in fallback to dns, possibly yielding EAI_NONAME for a hostname that should be defined locally, or an unwanted result from dns that the hosts file was intended to replace. - failure to open services resulted in EAI_SERVICE. - failure to open resolv.conf resulted in querying localhost rather than the configured nameservers. now, only permanent errors trigger the fallback behaviors above; all other errors are reportable to the caller as EAI_SYSTEM.
2015-09-25avoid attempting to lookup IP literals as hostnamesRich Felker1-27/+32
previously, __lookup_ipliteral only checked its argument against the requested address family, so IPv4 literals passed through to __lookup_name if the caller asked for only IPv6 results, and likewise for IPv6 literals when the caller asked for only IPv4. this resulted in spurious DNS lookups that reportedly even succeeded with some nameservers. now, __lookup_ipliteral attempts to parse its argument as both IPv4 and IPv6, and returns an error (to stop further search) rather than 0 (no results yet) if the form of the argument mismatches the requested address family. based on patch by Julien Ramseier.
2015-09-25make getaddrinfo return error if both host and service name are nullRich Felker1-0/+2
this case is specified as a mandatory ("shall fail") error. based on patch by Julien Ramseier.
2015-09-11fix uninitialized scopeid in lookups from hosts file and ip literalsTimo Teräs1-2/+2
2015-07-08fix negated return value of ns_skiprr, breakage in related functionsRich Felker1-1/+1
due to a reversed pointer difference computation, ns_skiprr always returned a negative value, which functions using it would interpret as an error. patch by Yu Lu.
2015-03-23fix internal buffer overrun in inet_ptonRich Felker1-2/+3
one stop condition for parsing abbreviated ipv6 addressed was missed, allowing the internal ip[] buffer to overflow. this patch adds the missing stop condition and masks the array index so that, in case there are any remaining stop conditions missing, overflowing the buffer is not possible.
2015-02-10make protocol table zero byte separated and add ipv6 protocolsTimo Teräs1-22/+26
2015-02-07make getaddrinfo support SOCK_RAW and other socket typesRich Felker4-34/+42
all socket types are accepted at this point, but that may be changed at a later time if the behavior is not meaningful for other types. as before, omitting type (a value of 0) gives both UDP and TCP results, and SOCK_DGRAM or SOCK_STREAM restricts to UDP or TCP, respectively. for other socket types, the service name argument is required to be a null pointer, and the protocol number provided by the caller is used.
2014-12-17add basic dns record parsing functionsRich Felker1-0/+171
based on patch by Timo Teräs, with some corrections to bounds checking code and other minor changes. while they are borderline scope creep, the functions added are fairly small and are roughly the minimum code needed to use the results of the res_query API without re-implementing error-prone DNS packet parsing, and they are used in practice by some kerberos related software and possibly other things. at this time there is no intent to implement further nameser.h API functions.
2014-09-05fix potential read past end of buffer in getnameinfo service name lookupRich Felker1-1/+1
if the loop stopped due to reaching the end of the string, the subsequent increment could possibly move the position one past the end of the buffer. no further writes happen, the reads cannot fault anyway unless the stack completely lacks any zero bytes, and reading junk should not yield an incorrect result from the function either. nonetheless the code was wrong and needs to be fixed.
2014-09-05remove incorrect and useless check in network service name lookup codeRich Felker1-1/+0
the condition was probably intended to be !*p rather than !p, but neither is needed here. the subsequent code naturally handles the case where it's already at end of string.
2014-09-05remove an extra layer of buffer copying in getnameinfo reverse dnsRich Felker1-3/+2
the outer getnameinfo function already has a properly-sized temporary buffer for storing the reverse dns (ptr) result. there is no reason for the callback to use a secondary buffer and copy it on success, and doing so potentially expanded the impact of the dn_expand bug that was fixed in commit 49d2c8c6bcf8c926e52c7f510033b6adc31355f5. this change reduces the code size by a small amount, and also reduces the run-time stack space requirements by about 256 bytes.
2014-09-04fix dn_expand empty name handling and offsets to 0Szabolcs Nagy1-6/+9
Empty name was rejected in dn_expand since commit 56b57f37a46dab432247bf29d96fcb11fbd02a6d which is a regression as reported by Natanael Copa. Furthermore if an offset pointer in a compressed name pointed to a terminating 0 byte (instead of a label) the returned name was not null terminated.
2014-07-29reimplement if_nameindex and getifaddrs using netlinkTimo Teräs4-184/+411
the previous implementations had several deficiencies, the most severe of which was the inability to report unconfigured interfaces or interfaces without ipv4 addresses. among the options discussed for fixing this, using netlink turned out to be the one with the least cost and most additional advantages. other improvements include: if_nameindex now avoids duplicates in the list it produces, but still includes legacy-style interface aliases if any are in use. getifaddrs now reports hardware addresses and includes the scope_id for link-local ipv6 addresses in the resulting address.
2014-07-26add support for LC_TIME and LC_MESSAGES translationsRich Felker2-2/+6
for LC_MESSAGES, translation of strerror and similar literal message functions is supported. for messages in other places (particularly the dynamic linker) that use format strings, translation is not yet supported. in order to make it possible and safe, such messages will need to be refactored to separate the textual content from the format. for LC_TIME, the day and month names and strftime-style format strings provided by nl_langinfo are supported for translation. however there may be limitations, as some of the original C-locale nl_langinfo strings are non-unique and thus perhaps non-suitable as keys. overall, the locale support activated by this commit should not be seen as complete and polished but as a basis for beginning to test locale functionality and implement locales.
2014-06-24add routing protocols to getprotoent-family functionsTimo Teräs1-0/+2
iptables and quagga need them to work.
2014-06-21implement result address sorting in the resolver (getaddrinfo, etc.)Rich Felker2-0/+136
2014-06-20fix gethostby*_r result pointer value on errorTimo Teräs2-0/+3
according to the documentation in the man pages, the GNU extension functions gethostbyaddr_r, gethostbyname_r and gethostbyname2_r are guaranteed to set the result pointer to NULL in case of error or no result.