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* avoid spurious lookup failures from badly-behaved nameserversRich Felker2014-06-071-5/+22
| | | | | | | | | | | | | | | | | | | | | | | | the results of a dns query, whether it's performed as part of one of the standard name-resolving functions or directly by res_send, should be a function of the query, not of the particular nameserver that responds to it. thus, all responses which indicate a failure or refusal by the nameserver, as opposed to a positive or negative result for the query, should be ignored. the strategy used is to re-issue the query immediately (but with a limit on the number of retries, in case the server is really broken) when a response code of 2 (server failure, typically transient) is seen, and otherwise take no action on bad responses (which generally indicate a misconfigured nameserver or one which the client does not have permission to use), allowing the normal retry interval to apply and of course accepting responses from other nameservers queried in parallel. empirically this matches the traditional resolver behavior for nameservers that respond with a code of 2 in the case where there is just a single nameserver configured. the behavior diverges when multiple nameservers are available, since musl is querying them in parallel. in this case we are mildly more aggressive at retrying.
* optimize SOCK_CLOEXEC fallback for socket functionRich Felker2014-06-061-2/+2
| | | | | | | | | the fcntl function is heavy, so make the syscall directly instead. also, avoid the code size and runtime overhead of querying the old flags, since it's reasonable to assume nothing will be set on a newly-created socket. this code is only used on old kernels which lack proper atomic close-on-exec support, so future changes that might invalidate such an assumption do not need to be considered.
* add SOCK_CLOEXEC fallback for socketpair on old kernelsRich Felker2014-06-061-1/+19
| | | | | as usual, this is non-atomic, but better than producing an error or failing to set the close-on-exec flag at all.
* implement dn_comp RFC 1035 domain name compressionSzabolcs Nagy2014-06-061-1/+102
| | | | | | | | the input name is validated, the other parameters are assumed to be valid (the list of already compressed names are not checked for infinite reference loops or out-of-bound offsets). names are handled case-sensitively for now.
* accept trailing . and empty domain namesSzabolcs Nagy2014-06-063-12/+16
| | | | | | trailing . should be accepted in domain name strings by convention (RFC 1034), host name lookup accepts "." but rejects empty "", res_* interfaces also accept empty name following existing practice.
* fix the domain name length limit checksSzabolcs Nagy2014-06-053-8/+8
| | | | | A domain name is at most 255 bytes long (RFC 1035), but the string representation is two bytes smaller so the strlen maximum is 253.
* fix multiple validation issues in dns response label parsingSzabolcs Nagy2014-06-051-4/+6
| | | | | | | | | | | | Due to an error introduced in commit fcc522c92335783293ac19df318415cd97fbf66b, checking of the remaining output buffer space was not performed correctly, allowing malformed input to write past the end of the buffer. In addition, the loop detection logic failed to account for the possibility of infinite loops with no output, which would hang the function. The output size is now limited more strictly so only names with valid length are accepted.
* fix missing function declarations in refactored ip literal parsing codeRich Felker2014-06-051-0/+1
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* add support for reverse port lookups from services file to getnameinfoRich Felker2014-06-041-4/+35
| | | | | this also affects the legacy getservbyport family, which uses getnameinfo as its backend.
* add support for reverse name lookups from hosts file to getnameinfoRich Felker2014-06-045-50/+122
| | | | | | | | | | | this also affects the legacy gethostbyaddr family, which uses getnameinfo as its backend. some other minor changes associated with the refactoring of source files are also made; in particular, the resolv.conf parser now uses the same code that's used elsewhere to handle ip literals, so as a side effect it can now accept a scope id for nameserver addressed with link-local scope.
* remove some dummy "ent" function aliases that duplicated real onesRich Felker2014-06-041-8/+0
| | | | | | | the service and protocol functions are defined also in other files, and the protocol ones are actually non-nops elsewhere, so the weak definitions in ent.c could have prevented the strong definitions from getting pulled in and used in some static programs.
* add support for ipv6 scope_id to getaddrinfo and getnameinfoRich Felker2014-06-043-8/+56
| | | | | | | | | | | | | | | | | | | | for all address types, a scope_id specified as a decimal value is accepted. for addresses with link-local scope, a string containing the interface name is also accepted. some changes are made to error handling to avoid unwanted fallbacks in the case where the scope_id is invalid: if an earlier name lookup backend fails with an error rather than simply "0 results", this failure now suppresses any later attempts with other backends. in getnameinfo, a light "itoa" type function is added for generating decimal scope_id results, and decimal port strings for services are also generated using this function now so as not to pull in the dependency on snprintf. in netdb.h, a definition for the NI_NUMERICSCOPE flag is added. this is required by POSIX (it was previously missing) and needed to allow callers to suppress interface-name lookups.
* fix if_nametoindex return value when interface does not existRich Felker2014-06-031-1/+1
| | | | | | the return value is unsigned, so negative results for "errors" do not make sense; 0 is the value reserved for when the interface name does not exist.
* fix negative response and non-response handling for dns queriesRich Felker2014-06-031-1/+4
| | | | | | | | | previously, all failures to obtain at least one address were treated as nonexistant names (EAI_NONAME). this failed to account for the possibility of transient failures (no response at all, or a response with rcode of 2, server failure) or permanent failures that do not indicate the nonexistence of the requested name. only an rcode of 3 should be treated as an indication of nonexistence.
* fix some validation checks in dns response parsing codeRich Felker2014-06-031-2/+3
| | | | | | | | since the buffer passed always has an actual size of 512 bytes, the maximum possible response packet size, no out-of-bounds access was possible; however, reading past the end of the valid portion of the packet could cause the parser to attempt to process junk as answer content.
* remove cruft from old resolver and numeric ip parsingRich Felker2014-06-026-79/+49
| | | | | | | | | the old resolver code used a function __ipparse which contained the logic for inet_addr and inet_aton, which is needed in getaddrinfo. this was phased out in the resolver overhaul in favor of directly using inet_aton and inet_pton as appropriate. this commit cleans up some stuff that was left behind.
* switch standard resolver functions to use the new dns backendRich Felker2014-06-024-309/+145
| | | | | | | | | | this is the third phase of the "resolver overhaul" project. this commit removes all of the old dns code, and switches the __lookup_name backend (used by getaddrinfo, etc.) and the getnameinfo function to use the newly implemented __res_mkquery and __res_msend interfaces. for parsing the results, a new callback-based __dns_parse function, based on __dns_get_rr from the old dns code, is used.
* fix uninitialized variable in new __res_msend dns functionRich Felker2014-06-021-0/+1
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* implement new dns backend, res_send and other legacy resolver functionsRich Felker2014-06-026-18/+263
| | | | | | | | | | | | | | | | | | this is the second phase of the "resolver overhaul" project. the key additions in this commit are the __res_msend and __res_mkquery functions, which have been factored so as to provide a backend for both the legacy res_* functions and the standard getaddrinfo and getnameinfo functions. the latter however are still using the old backend code; there is code duplication which still needs to be removed, and this will be the next phase of the resolver overhaul. __res_msend is derived from the old __dns_doqueries function, but generalized to send arbitrary caller-provided packets in parallel rather than producing the parallel queries itself. this allows it to be used (completely trivially) as a backend for res_send. the factored-out query generation code, with slightly more generality, is now part of __res_mkquery.
* add ipsec and tunneling protocols to getprotoent-family functionsTimo Teräs2014-06-021-0/+4
| | | | | iptables and ipsec-tools among others require these to function properly.
* fix off-by-one in checking hostname length in new resolver backendRich Felker2014-06-021-2/+2
| | | | | | | | | this bug was introduced in the recent resolver overhaul commits. it likely had visible symptoms. these were probably limited to wrongly accepting truncated versions of over-long names (vs rejecting them), as opposed to stack-based overflows or anything more severe, but no extensive checks were made. there have been no releases where this bug was present.
* improve getservbyname_r using new resolver backendRich Felker2014-06-012-22/+16
| | | | | | | | | | | | now that host and service lookup have been separated in the backend, there's no need for service lookup functions to pull in the host lookup code. moreover, dynamic allocation is no longer needed, so this function should now be async-signal-safe. it's also significantly smaller. one change in getservbyname is also made: knowing that getservbyname_r needs only two character pointers in the caller-provided buffer, some wasted bss can be avoided.
* improve gethostbyname2_r using new resolver backendRich Felker2014-06-011-35/+22
| | | | | | | | these changes reduce the size of the function somewhat and remove many of its dependencies, including free. in principle it should now be async-signal-safe, but this has not been verified in detail. minor changes to error handling are also made.
* refactor getaddrinfo and add support for most remaining featuresRich Felker2014-05-314-228/+360
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | this is the first phase of the "resolver overhaul" project. conceptually, the results of getaddrinfo are a direct product of a list of address results and a list of service results. the new code makes this explicit by computing these lists separately and combining the results. this adds support for services that have both tcp and udp versions, where the caller has not specified which it wants, and eliminates a number of duplicate code paths which were all producing the final output addrinfo structures, but in subtly different ways, making it difficult to implement any of the features which were missing. in addition to the above benefits, the refactoring allows for legacy functions like gethostbyname to be implemented without using the getaddrinfo function itself. such changes to the legacy functions have not yet been made, however. further improvements include matching of service alias names from /etc/services (previously only the primary name was supported), returning multiple results from /etc/hosts (previously only the first matching line was honored), and support for the AI_V4MAPPED and AI_ALL flags. features which remain unimplemented are IDN translations (encoding non-ASCII hostnames for DNS lookup) and the AI_ADDRCONFIG flag. at this point, the DNS-based name resolving code is still based on the old interfaces in __dns.c, albeit somewhat simpler in its use of them. there may be some dead code which could already be removed, but changes to this layer will be a later phase of the resolver overhaul.
* add fallback emulation for accept4 on old kernelsRich Felker2014-02-211-1/+12
| | | | | | | | | | | | the other atomic FD_CLOEXEC interfaces (dup3, pipe2, socket) already had such emulation in place. the justification for doing the emulation here is the same as for the other functions: it allows applications to simply use accept4 rather than having to have their own fallback code for ENOSYS/EINVAL (which one you get is arch-specific!) and there is no reasonable way an application could benefit from knowing the operation is emulated/non-atomic since there is no workaround at the application level for non-atomicity (that is the whole reason these interfaces were added).
* add ipv6 and icmpv6 to getprotoent-family functionsRich Felker2014-02-131-1/+3
| | | | based on patch by orc.
* fix typo in table for getprotoent that caused out-of-bound readsRich Felker2014-02-131-1/+1
| | | | | | | | this was unlikely to lead to any crash or dangerous behavior, but caused adjacent string constants to be treated as part of the protocols table, possibly returning nonsensical results for unknown protocol names/numbers or when getprotoent was called in a loop to enumerate all protocols.
* fix argument types for legacy function inet_makeaddrRich Felker2014-01-061-2/+1
| | | | | | the type int was taken from seemingly erroneous man pages. glibc uses in_addr_t (uint32_t), and semantically, the arguments should be unsigned.
* implement legacy function herrorRich Felker2013-12-201-0/+8
| | | | based on patch by Timo Teräs; greatly simplified to use fprintf.
* include cleanups: remove unused headers and add feature test macrosSzabolcs Nagy2013-12-1213-18/+3
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* remove an unnecessary check in inet_ptonSzabolcs Nagy2013-12-121-2/+1
| | | | | at most 4 hexadecimal digits are processed in one field so the value cannot overflow. the netdb.h header was not used.
* support mix of IPv4 and v6 nameservers in resolv.confRich Felker2013-11-301-5/+31
| | | | | | | | | | | | | | | | | a v6 socket will only be used if there is at least one v6 nameserver address. if the kernel lacks v6 support, the code will fall back to using a v4 socket and requests to v6 servers will silently fail. when using a v6 socket, v4 addresses are converted to v4-mapped form and setsockopt is used to ensure that the v6 socket can accept both v4 and v6 traffic (this is on-by-default on Linux but the default is configurable in /proc and so it needs to be set explicitly on the socket level). this scheme avoids increasing resource usage during lookups and allows the existing network io loop to be used without modification. previously, nameservers whose address family did not match the address family of the first-listed nameserver were simply ignored. prior to recent __ipparse fixes, they were not ignored but erroneously parsed.
* reject invalid address families in getaddrinfoRich Felker2013-11-271-0/+3
| | | | | | | subsequent code assumes the address family requested is either unspecified or one of IPv4/IPv6, and could malfunction if this constraint is not met, so other address families should be explicitly rejected.
* remove duplicate includes from dynlink.c, strfmon.c and getaddrinfo.cSzabolcs Nagy2013-11-251-3/+0
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* Fix dn_comp prototype and add stubMichael Forney2013-11-241-0/+9
| | | | This function is used by ping6 from iputils.
* Fix dn_expand pointer followingMichael Forney2013-11-231-1/+1
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* fix fd leak (missing close-on-exec) in getifaddrsRich Felker2013-11-201-1/+1
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* fix regression in inet_aton due to misinterpretation of __ipparse returnRich Felker2013-11-022-3/+3
| | | | | | | inet_aton returns a boolean success value, whereas __ipparse returns 0 on success and -1 on failure. also change the conditional in inet_addr to be consistent with other uses of __ipparse where only negative values are treated as failure.
* fix inet_ptonSzabolcs Nagy2013-10-231-26/+19
| | | | | | | | * parse IPv4 dotted-decimal correctly (without strtoul, no leading zeros) * disallow single leading ':' in IPv6 address * allow at most 4 hex digits in IPv6 address (according to RFC 2373) * have enough hex fields in IPv4 mapped IPv6 address * disallow leading zeros in IPv4 mapped IPv6 address
* fix __ipparse to parse the generic numbers-and-dots IPv4 format correctlySzabolcs Nagy2013-10-221-5/+12
| | | | | | | * allow at most 4 parts * bounds check the parts correctly * disallow leading whitespace and sign * check the address family before falling back to IPv6
* fix inet_aton to accept the generic "numbers-and-dots" IPv4 address formatSzabolcs Nagy2013-10-221-1/+4
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* split inet_addr and inet_ntoa back into their own filesRich Felker2013-10-213-16/+21
| | | | | | | despite being practically deprecated, these functions are still part of the standard and thus cannot reside in a file that also contains namespace pollution. this reverts some of the changes made in commit e40f48a421a9176e3e298b5bac75f0355b219e58.
* fix return value for inet_pton in ipv6 failure casesRich Felker2013-10-191-6/+6
| | | | | in the case of input that does not match the expected form, the correct return value is 0, not -1.
* fix regression in dn_expand/reverse dnsRich Felker2013-08-231-1/+1
| | | | | | off-by-one error copying the name components was yielding junk at the beginning and truncating one character at the end (of every component).
* fix length computation in dn_expandRich Felker2013-08-141-3/+5
| | | | | | | there are two possible points where the length is evaluated: either the first 'compression' jump, or the null terminator if no jumps have taken place yet. the previous code only measured the length of the first component.
* de-duplicate dn_expand, fix return value and signature, clean upRich Felker2013-08-142-48/+23
| | | | | | | | | | | | | | | | | the duplicate code in dn_expand and its incorrect return values are both results of the history of the code: the version in __dns.c was originally written with no awareness of the legacy resolver API, and was later copy-and-paste duplicated to provide the legacy API. this commit is the first of a series that will restructure the internal dns code to share as much code as possible with the legacy resolver API functions. I have also removed the loop detection logic, since the output buffer length limit naturally prevents loops. in order to avoid long runtime when encountering a loop if the caller provided a ridiculously long buffer, the caller-provided length is clamped at the maximum dns name length.
* fix undefined strcpy call in inet_ntopRich Felker2013-07-251-1/+1
| | | | | source and dest arguments for strcpy cannot overlap, so memmove must be used here. the length is already known from the above loop.
* make inet_ntop format v4-mapped ipv6 addresses properlyRich Felker2013-07-251-8/+14
| | | | | | | | | | | | | | based on a patch by orc. POSIX actually fails to specify the format of the ntop conversion; presumably, any output that will correctly round-trip back via the (well-specified) pton operation is acceptable. the new behavior is much more convenient than the old, however. this patch also affects getnameinfo, which is implemented in terms of inet_ntop and which is the preferred interface for performing this conversion. I've also removed some inexplicable cruft (filling the buffer with 'x' before doing anything) whose origin I was unable to track down.
* make getaddrinfo with AF_UNSPEC and null host return both IPv4 and v6Rich Felker2013-07-241-14/+23
| | | | | | based on a patch by orc, with indexing and flow control cleaned up a little bit. this code is all going to be replaced at some point in the near future.
* fix missing SOCK_CLOEXEC in various functions that use sockets internallyRich Felker2013-07-094-4/+4
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