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85050ac5a2
this was apparently omitted long ago out of a lack of understanding of its importance and the fact that POSIX doesn't specify it. despite not being officially standardized, however, it turns out that at least AIX, glibc, NetBSD, OpenBSD, QNX, and Solaris document and support it. in certain usage cases, such as implementing a DNS gateway on top of the stub resolver interfaces, it's necessary to distinguish the case where a name does not exit (NxDomain) from one where it exists but has no addresses (or other records) of the requested type (NODATA). in fact, even the legacy gethostbyname API had this distinction, which we were previously unable to support correctly because the backend lacked it. apart from fixing an important functionality gap, adding this distinction helps clarify to users how search domain fallback works (falling back in cases corresponding to EAI_NONAME, not in ones corresponding to EAI_NODATA), a topic that has been a source of ongoing confusion and frustration. as a result of this change, EAI_NONAME is no longer a valid universal error code for getaddrinfo in the case where AI_ADDRCONFIG has suppressed use of all address families. in order to return an accurate result in this case, getaddrinfo is modified to still perform at least one lookup. this will almost surely fail (with a network error, since there is no v4 or v6 network to query DNS over) unless a result comes from the hosts file or from ip literal parsing, but in case it does succeed, the result is replaced by EAI_NODATA. glibc has a related error code, EAI_ADDRFAMILY, that could be used for the AI_ADDRCONFIG case and certain NODATA cases, but distinguishing them properly in full generality seems to require additional DNS queries that are otherwise not useful. on glibc, it is only used for ip literals with mismatching family, not for DNS or hosts file results where the name has addresses only in the opposite family. since this seems misleading and inconsistent, and since EAI_NODATA already covers the semantic case where the "name" exists but doesn't have any addresses in the requested family, we do not adopt EAI_ADDRFAMILY at this time. this could be changed at some point if desired, but the logic for getting all the corner cases with AI_ADDRCONFIG right is slightly nontrivial.
158 lines
3.9 KiB
C
158 lines
3.9 KiB
C
#ifndef _NETDB_H
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#define _NETDB_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <features.h>
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#include <netinet/in.h>
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#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
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#define __NEED_size_t
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#include <bits/alltypes.h>
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#endif
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struct addrinfo {
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int ai_flags;
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int ai_family;
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int ai_socktype;
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int ai_protocol;
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socklen_t ai_addrlen;
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struct sockaddr *ai_addr;
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char *ai_canonname;
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struct addrinfo *ai_next;
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};
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#define AI_PASSIVE 0x01
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#define AI_CANONNAME 0x02
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#define AI_NUMERICHOST 0x04
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#define AI_V4MAPPED 0x08
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#define AI_ALL 0x10
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#define AI_ADDRCONFIG 0x20
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#define AI_NUMERICSERV 0x400
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#define NI_NUMERICHOST 0x01
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#define NI_NUMERICSERV 0x02
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#define NI_NOFQDN 0x04
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#define NI_NAMEREQD 0x08
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#define NI_DGRAM 0x10
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#define NI_NUMERICSCOPE 0x100
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#define EAI_BADFLAGS -1
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#define EAI_NONAME -2
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#define EAI_AGAIN -3
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#define EAI_FAIL -4
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#define EAI_NODATA -5
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#define EAI_FAMILY -6
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#define EAI_SOCKTYPE -7
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#define EAI_SERVICE -8
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#define EAI_MEMORY -10
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#define EAI_SYSTEM -11
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#define EAI_OVERFLOW -12
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int getaddrinfo (const char *__restrict, const char *__restrict, const struct addrinfo *__restrict, struct addrinfo **__restrict);
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void freeaddrinfo (struct addrinfo *);
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int getnameinfo (const struct sockaddr *__restrict, socklen_t, char *__restrict, socklen_t, char *__restrict, socklen_t, int);
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const char *gai_strerror(int);
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/* Legacy functions follow (marked OBsolete in SUS) */
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struct netent {
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char *n_name;
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char **n_aliases;
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int n_addrtype;
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uint32_t n_net;
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};
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struct hostent {
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char *h_name;
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char **h_aliases;
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int h_addrtype;
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int h_length;
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char **h_addr_list;
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};
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#define h_addr h_addr_list[0]
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struct servent {
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char *s_name;
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char **s_aliases;
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int s_port;
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char *s_proto;
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};
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struct protoent {
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char *p_name;
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char **p_aliases;
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int p_proto;
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};
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void sethostent (int);
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void endhostent (void);
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struct hostent *gethostent (void);
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void setnetent (int);
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void endnetent (void);
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struct netent *getnetent (void);
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struct netent *getnetbyaddr (uint32_t, int);
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struct netent *getnetbyname (const char *);
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void setservent (int);
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void endservent (void);
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struct servent *getservent (void);
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struct servent *getservbyname (const char *, const char *);
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struct servent *getservbyport (int, const char *);
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void setprotoent (int);
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void endprotoent (void);
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struct protoent *getprotoent (void);
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struct protoent *getprotobyname (const char *);
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struct protoent *getprotobynumber (int);
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#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE) || defined(_POSIX_SOURCE) \
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|| (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE+0 < 200809L) \
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|| (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE+0 < 700)
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struct hostent *gethostbyname (const char *);
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struct hostent *gethostbyaddr (const void *, socklen_t, int);
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#ifdef __GNUC__
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__attribute__((const))
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#endif
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int *__h_errno_location(void);
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#define h_errno (*__h_errno_location())
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#define HOST_NOT_FOUND 1
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#define TRY_AGAIN 2
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#define NO_RECOVERY 3
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#define NO_DATA 4
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#define NO_ADDRESS NO_DATA
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#endif
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#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
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void herror(const char *);
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const char *hstrerror(int);
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int gethostbyname_r(const char *, struct hostent *, char *, size_t, struct hostent **, int *);
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int gethostbyname2_r(const char *, int, struct hostent *, char *, size_t, struct hostent **, int *);
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struct hostent *gethostbyname2(const char *, int);
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int gethostbyaddr_r(const void *, socklen_t, int, struct hostent *, char *, size_t, struct hostent **, int *);
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int getservbyport_r(int, const char *, struct servent *, char *, size_t, struct servent **);
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int getservbyname_r(const char *, const char *, struct servent *, char *, size_t, struct servent **);
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#define EAI_NODATA -5
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#define EAI_ADDRFAMILY -9
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#define EAI_INPROGRESS -100
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#define EAI_CANCELED -101
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#define EAI_NOTCANCELED -102
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#define EAI_ALLDONE -103
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#define EAI_INTR -104
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#define EAI_IDN_ENCODE -105
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#define NI_MAXHOST 255
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#define NI_MAXSERV 32
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif
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