path: root/src/network
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2020-09-03fix missing newline in herror outputRich Felker-1/+1
2020-08-30restore h_errno ABI compatibility with ancient binariesRich Felker-0/+4
prior to commit e68c51ac46a9f273927aef8dcebc89912ab19ece, h_errno was actually an external data object not a macro. bring back the symbol, and use it as the storage for the main thread's h_errno. technically this still doesn't provide full compatibility if the application was multithreaded, but at the time there were no res_* functions (and they did not set h_errno anyway), so any use of h_errno would have been via thread-unsafe functions. thus a solution that just fixes single-threaded applications seems acceptable.
2020-08-24report res_query failures, including nxdomain/nodata, via h_errnoRich Felker-1/+15
while it's not clearly documented anywhere, this is the historical behavior which some applications expect. applications which need to see the response packet in these cases, for example to distinguish between nonexistence in a secure vs insecure zone, must already use res_mkquery with res_send in order to be portable, since most if not all other implementations of res_query don't provide it.
2020-08-24make h_errno thread-localRich Felker-4/+2
the framework to do this always existed but it was deemed unnecessary because the only [ex-]standard functions using h_errno were not thread-safe anyway. however, some of the nonstandard res_* functions are also supposed to set h_errno to indicate the cause of error, and were unable to do so because it was not thread-safe. this change is a prerequisite for fixing them.
2020-08-05in hosts file lookups, honor first canonical name regardless of familyRich Felker-1/+1
prior to this change, the canonical name came from the first hosts file line matching the requested family, so the canonical name for a given hostname could differ depending on whether it was requested with AF_UNSPEC or a particular family (AF_INET or AF_INET6). now, the canonical name is deterministically the first one to appear with the requested name as an alias.
2020-08-04in hosts file lookups, use only first match for canonical nameRich Felker-2/+7
the existing code clobbered the canonical name already discovered every time another matching line was found, which will necessarily be the case when a hostname has both IPv4 and v6 definitions. patch by Wolf.
2020-05-19fix return value of res_send, res_query on errors from nameserverRich Felker-1/+1
the internal __res_msend returns 0 on timeout without having obtained any conclusive answer, but in this case has not filled in meaningful anslen. res_send wrongly treated that as success, but returned a zero answer length. any reasonable caller would eventually end up treating that as an error when attempting to parse/validate it, but it should just be reported as an error. alternatively we could return the last-received inconclusive answer (typically servfail), but doing so would require internal changes in __res_msend. this may be considered later.
2020-05-19fix handling of errors resolving one of paired A+AAAA queryRich Felker-4/+7
the old logic here likely dates back, at least in inspiration, to before it was recognized that transient errors must not be allowed to reflect the contents of successful results and must be reported to the application. here, the dns backend for getaddrinfo, when performing a paired query for v4 and v6 addresses, accepted results for one address family even if the other timed out. (the __res_msend backend does not propagate error rcodes back to the caller, but continues to retry until timeout, so other error conditions were not actually possible.) this patch moves the checks to take place before answer parsing, and performs them for each answer rather than only the answer to the first query. if nxdomain is seen it's assumed to apply to both queries since that's how dns semantics work.
2020-05-18set AD bit in dns queries, suppress for internal useRich Felker-0/+3
the AD (authenticated data) bit in outgoing dns queries is defined by rfc3655 to request that the nameserver report (via the same bit in the response) whether the result is authenticated by DNSSEC. while all results returned by a DNSSEC conforming nameserver will be either authenticated or cryptographically proven to lack DNSSEC protection, for some applications it's necessary to be able to distinguish these two cases. in particular, conforming and compatible handling of DANE (TLSA) records requires enforcing them only in signed zones. when the AD bit was first defined for queries, there were reports of compatibility problems with broken firewalls and nameservers dropping queries with it set. these problems are probably a thing of the past, and broken nameservers are already unsupported. however, since there is no use in the AD bit with the netdb.h interfaces, explicitly clear it in the queries they make. this ensures that, even with broken setups, the standard functions will work, and at most the res_* functions break.
2020-02-22use __socketcall to simplify socket()Rich Felker-5/+5
commit 59324c8b0950ee94db846a50554183c845ede160 added __socketcall analogous to __syscall, returning the negated error rather than setting errno. use it to simplify the fallback path of socket(), avoiding extern calls and access to errno. Author: Rich Felker <> Date: Tue Jul 30 17:51:16 2019 -0400 make __socketcall analogous to __syscall, error-returning
2019-12-17hook recvmmsg up to SO_TIMESTAMP[NS] fallback for pre-time64 kernelsRich Felker-6/+14
always try the time64 syscall first since we can use its success to conclude that no conversion is needed (any setsockopt for the timestamp options would have succeeded without need for fallbacks). otherwise, we have to remember the original controllen for each msghdr, requiring O(vlen) space, so vlen must be bounded. linux clamps it to IOV_MAX for sendmmsg only (not recvmmsg), but doing the same for recvmmsg is not unreasonable, especially since the limitation will only apply to old kernels. we could optimize to avoid trying SYS_recvmmsg_time64 first if all msghdrs have controllen zero, or support unlimited vlen by looping and emulating the timeout logic, but I'm not inclined to do complex and error-prone optimizations on a function that has so many underlying problems it should really never be used.
2019-12-17implement SO_TIMESTAMP[NS] fallback for kernels without time64 versionsRich Felker-0/+63
the definitions of SO_TIMESTAMP* changed on 32-bit archs in commit 38143339646a4ccce8afe298c34467767c899f51 to the new versions that provide 64-bit versions of timeval/timespec structure in control message payload. socket options, being state attached to the socket rather than function calls, are not trivial to implement as fallbacks on ENOSYS, and support for them was initially omitted on the assumption that the ioctl-based polling alternatives (SIOCGSTAMP*) could be used instead by applications if setsockopt fails. unfortunately, it turns out that SO_TIMESTAMP is sufficiently old and widely supported that a number of applications assume it's available and treat errors as fatal. this patch introduces emulation of SO_TIMESTAMP[NS] on pre-time64 kernels by falling back to setting the "_OLD" (time32) versions of the options if the time64 ones are not recognized, and performing translation of the SCM_TIMESTAMP[NS] control messages in recvmsg. since recvmsg does not know whether its caller is legacy time32 code or time64, it performs translation for any SCM_TIMESTAMP[NS]_OLD control messages it sees, leaving the original time32 timestamp as-is (it can't be rewritten in-place anyway, and memmove would be mildly expensive) and appending the converted time64 control message at the end of the buffer. legacy time32 callers will see the converted one as a spurious control message of unknown type; time64 callers running on pre-time64 kernels will see the original one as a spurious control message of unknown type. a time64 caller running on a kernel with native time64 support will only see the time64 version of the control message. emulation of SO_TIMESTAMPING is not included at this time since (1) applications which use it seem to be prepared for the possibility that it's not present or working, and (2) it can also be used in sendmsg control messages, in a manner that looks complex to emulate completely, and costly even when running on a time64-supporting kernel. corresponding changes in recvmmsg are not made at this time; they will be done separately.
2019-08-07fix regression in recvmmsg with no timeoutRich Felker-1/+1
somewhat analogous to commit d0b547dfb5f7678cab6bc39dd736ed6454357ca4, but here the omission of the null timeout check was in the time64 syscall code path. this code is not yet used except on x32.
2019-07-31get/setsockopt: add fallback for new time64 SO_RCVTIMEO/SO_SNDTIMEORich Felker-2/+57
without this, the SO_RCVTIMEO and SO_SNDTIMEO socket options would stop working on pre-5.1 kernels after time_t is switched to 64-bit and their values are changed to the new time64 versions. new code is written such that it's statically unreachable on 64-bit archs, and on existing 32-bit archs until the macro values are changed to activate 64-bit time_t.
2019-07-29recvmmsg: add time64 syscall support, decouple 32-bit time_tRich Felker-0/+18
the time64 syscall is used only if the timeout does not fit in 32 bits. after preprocessing, the code is unchanged on 64-bit archs. for 32-bit archs, the timeout now goes through an intermediate copy, meaning that the caller does not get back the updated timeout. this is based on my reading of the documentation, which does not document the updating as a contract you can rely on, and mentions that the whole recvmmsg timeout mechanism is buggy and unlikely to be useful. if it turns out that there's interest in making the remaining time officially available to callers, such functionality could be added back later.
2019-03-13handle labels with 8-bit byte values in dn_skipnameRyan Fairfax-2/+5
The original logic considered each byte until it either found a 0 value or a value >= 192. This means if a string segment contained any byte >= 192 it was interepretted as a compressed segment marker even if it wasn't in a position where it should be interpretted as such. The fix is to adjust dn_skipname to increment by each segments size rather than look at each character. This avoids misinterpretting string segment characters by not considering those bytes.
2019-02-20fix spurious undefined behavior in getaddrinfoRich Felker-3/+2
addressing &out[k].sa was arguably undefined, despite &out[k] being defined the slot one past the end of an array, since the member access .sa is intervening between the [] operator and the & operator.
2019-02-20fix invalid free of partial addrinfo list with multiple servicesRich Felker-1/+1
the backindex stored by getaddrinfo to allow freeaddrinfo to perform partial-free wrongly used the address result index, rather than the output slot index, and thus was only valid when they were equal (nservs==1). patch based on report with proposed fix by Markus Wichmann.
2018-10-04allow freeaddrinfo of arbitrary sublists of addrinfo listRich Felker-8/+25
the specification for freeaddrinfo allows it to be used to free "arbitrary sublists" of the list returned by getaddrinfo. it's not clearly stated how such sublists come into existence, but the interpretation seems to be that the application can edit the ai_next pointers to cut off a portion of the list and then free it. actual freeing of individual list slots is contrary to the design of our getaddrinfo implementation, which has no failure paths after making a single allocation, so that light callers can avoid linking realloc/free. freeing individual slots is also incompatible with sharing the string for ai_canonname, which the current implementation does despite no requirement that it be present except on the first result. so, rather than actually freeing individual slots, provide a way to find the start of the allocated array, and reference-count it, freeing the memory all at once after the last slot has been freed. since the language in the spec is "arbitrary sublists", no provision for handling other constructs like multiple lists glued together, circular links, etc. is made. presumably passing such a construct to freeaddrinfo produces undefined behavior.
2018-09-19fix getaddrinfo regression with AI_ADDRCONFIG on some configurationsRich Felker-1/+10
despite not being documented to do so in the standard or Linux documentation, attempts to udp connect to or ::1 generate EADDRNOTAVAIL when the loopback device is not configured and there is no default route for IPv6. this caused getaddrinfo with AI_ADDRCONFIG to fail with EAI_SYSTEM and EADDRNOTAVAIL on some no-IPv6 configurations, rather than the intended behavior of detecting IPv6 as unsuppported and producing IPv4-only results. previously, only EAFNOSUPPORT was treated as unavailability of the address family being probed. instead, treat all errors related to inability to get an address or route as conclusive that the family being probed is unsupported, and only fail with EAI_SYSTEM on other errors. further improvements may be desirable, such as reporting EAI_AGAIN instead of EAI_SYSTEM for errors which are expected to be transient, but this patch should suffice to fix the serious regression.
2018-09-12reduce spurious inclusion of libc.hRich Felker-13/+4
libc.h was intended to be a header for access to global libc state and related interfaces, but ended up included all over the place because it was the way to get the weak_alias macro. most of the inclusions removed here are places where weak_alias was needed. a few were recently introduced for hidden. some go all the way back to when libc.h defined CANCELPT_BEGIN and _END, and all (wrongly implemented) cancellation points had to include it. remaining spurious users are mostly callers of the LOCK/UNLOCK macros and files that use the LFS64 macro to define the awful *64 aliases. in a few places, new inclusion of libc.h is added because several internal headers no longer implicitly include libc.h. declarations for __lockfile and __unlockfile are moved from libc.h to stdio_impl.h so that the latter does not need libc.h. putting them in libc.h made no sense at all, since the macros in stdio_impl.h are needed to use them correctly anyway.
2018-09-12remove or make static various unused __-prefixed symbolsRich Felker-7/+3
2018-09-12apply hidden visibility to various remaining internal interfacesRich Felker-7/+8
2018-09-12overhaul internally-public declarations using wrapper headersRich Felker-16/+2
commits leading up to this one have moved the vast majority of libc-internal interface declarations to appropriate internal headers, allowing them to be type-checked and setting the stage to limit their visibility. the ones that have not yet been moved are mostly namespace-protected aliases for standard/public interfaces, which exist to facilitate implementing plain C functions in terms of POSIX functionality, or C or POSIX functionality in terms of extensions that are not standardized. some don't quite fit this description, but are "internally public" interfacs between subsystems of libc. rather than create a number of newly-named headers to declare these functions, and having to add explicit include directives for them to every source file where they're needed, I have introduced a method of wrapping the corresponding public headers. parallel to the public headers in $(srcdir)/include, we now have wrappers in $(srcdir)/src/include that come earlier in the include path order. they include the public header they're wrapping, then add declarations for namespace-protected versions of the same interfaces and any "internally public" interfaces for the subsystem they correspond to. along these lines, the wrapper for features.h is now responsible for the definition of the hidden, weak, and weak_alias macros. this means source files will no longer need to include any special headers to access these features. over time, it is my expectation that the scope of what is "internally public" will expand, reducing the number of source files which need to include *_impl.h and related headers down to those which are actually implementing the corresponding subsystems, not just using them.
2018-09-12move __res_msend_rc declaration to lookup.hRich Felker-1/+1
unlike the other res/dn functions, this one is tied to struct resolvconf which is not a public interface, so put it in the private header for its subsystem.
2018-09-12move and deduplicate declarations of __dns_parse to make it checkableRich Felker-2/+3
the source file for this function is completely standalone, but it doesn't seem worth adding a header just for it, so declare it in lookup.h for now.
2018-09-12fix issues from public functions defined without declaration visibleRich Felker-2/+7
policy is that all public functions which have a public declaration should be defined in a context where that public declaration is visible, to avoid preventable type mismatches. an audit performed using GCC's -Wmissing-declarations turned up the violations corrected here. in some cases the public header had not been included; in others, a feature test macro needed to make the declaration visible had been omitted. in the case of gethostent and getnetent, the omission seems to have been intentional, as a hack to admit a single stub definition for both functions. this kind of hack is no longer acceptable; it's UB and would not fly with LTO or advanced toolchains. the hack is undone to make exposure of the declarations possible.
2018-09-02fix stack-based oob memory clobber in resolver's result sortingRich Felker-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 Felker-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 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 Felker-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 Jones-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 Felker-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. Wilcox-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 Felker-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 Felker-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 Felker-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 Felker-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 Felker-1/+5
2016-09-24fix getservby*_r result pointer value on errorDaniel Sabogal-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 Sabogal-2/+0
this case statement was accidently left behind when this function was refactored in commit e8f39ca4898237cf71657500f0b11534c47a0521.
2016-09-16fix if_indextoname error caseDaniel Sabogal-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 Felker-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 Copa-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 Copa-0/+4
don't send a query that may be malformed.
2016-06-27fix misaligned address buffers in gethostbyname[2][_r] resultsRich Felker-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 Kelley-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 Vaněk-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 Teräs-0/+1
2016-03-02handle non-matching address family entries in hosts fileRich Felker-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 Felker-16/+22