.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved .TH "" 0P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" .\" .SH NAME netdb.h \- definitions for network database operations .SH SYNOPSIS .LP \fB#include \fP .SH DESCRIPTION .LP The \fI\fP header may define the \fBin_port_t\fP type and the \fBin_addr_t\fP type as described in \fI\fP . .LP The \fI\fP header shall define the \fBhostent\fP structure that includes at least the following members: .sp .RS .nf \fBchar *h_name \fP Official name of the host. \fB char **h_aliases \fP A pointer to an array of pointers to \fB \fP alternative host names, terminated by a \fB \fP null pointer. \fB int h_addrtype \fP Address type. \fB int h_length \fP The length, in bytes, of the address. \fB char **h_addr_list \fP A pointer to an array of pointers to network \fB \fP addresses (in network byte order) for the host, \fB \fP terminated by a null pointer. \fB \fP .fi .RE .LP The \fI\fP header shall define the \fBnetent\fP structure that includes at least the following members: .sp .RS .nf \fBchar *n_name \fP Official, fully-qualified (including the \fB \fP domain) name of the host. \fB char **n_aliases \fP A pointer to an array of pointers to \fB \fP alternative network names, terminated by a \fB \fP null pointer. \fB int n_addrtype \fP The address type of the network. \fB uint32_t n_net \fP The network number, in host byte order. \fB \fP .fi .RE .LP The \fBuint32_t\fP type shall be defined as described in \fI\fP \&. .LP The \fI\fP header shall define the \fBprotoent\fP structure that includes at least the following members: .sp .RS .nf \fBchar *p_name \fP Official name of the protocol. \fB char **p_aliases \fP A pointer to an array of pointers to \fB \fP alternative protocol names, terminated by \fB \fP a null pointer. \fB int p_proto \fP The protocol number. \fB \fP .fi .RE .LP The \fI\fP header shall define the \fBservent\fP structure that includes at least the following members: .sp .RS .nf \fBchar *s_name \fP Official name of the service. \fB char **s_aliases \fP A pointer to an array of pointers to \fB \fP alternative service names, terminated by \fB \fP a null pointer. \fB int s_port \fP The port number at which the service \fB \fP resides, in network byte order. \fB char *s_proto \fP The name of the protocol to use when \fB \fP contacting the service. \fB \fP .fi .RE .LP The \fI\fP header shall define the IPPORT_RESERVED macro with the value of the highest reserved Internet port number. .LP When the \fI\fP header is included, \fIh_errno\fP shall be available as a modifiable lvalue of type \fBint\fP. It is unspecified whether \fIh_errno\fP is a macro or an identifier declared with external linkage. .LP The \fI\fP header shall define the following macros for use as error values for \fIgethostbyaddr\fP() and \fIgethostbyname\fP(): .sp .RS .nf HOST_NOT_FOUND NO_DATA NO_RECOVERY TRY_AGAIN .fi .RE .SS Address Information Structure .LP The \fI\fP header shall define the \fBaddrinfo\fP structure that includes at least the following members: .sp .RS .nf \fBint ai_flags \fP Input flags. \fB int ai_family \fP Address family of socket. \fB int ai_socktype \fP Socket type. \fB int ai_protocol \fP Protocol of socket. \fB socklen_t ai_addrlen \fP Length of socket address. \fB struct sockaddr *ai_addr \fP Socket address of socket. \fB char *ai_canonname \fP Canonical name of service location. \fB struct addrinfo *ai_next \fP Pointer to next in list. \fB \fP .fi .RE .LP The \fI\fP header shall define the following macros that evaluate to bitwise-distinct integer constants for use in the \fIflags\fP field of the \fBaddrinfo\fP structure: .TP 7 AI_PASSIVE Socket address is intended for \fIbind\fP(). .TP 7 AI_CANONNAME .sp Request for canonical name. .TP 7 AI_NUMERICHOST .sp Return numeric host address as name. .TP 7 AI_NUMERICSERV .sp Inhibit service name resolution. .TP 7 AI_V4MAPPED If no IPv6 addresses are found, query for IPv4 addresses and return them to the caller as IPv4-mapped IPv6 addresses. .TP 7 AI_ALL Query for both IPv4 and IPv6 addresses. .TP 7 AI_ADDRCONFIG .sp Query for IPv4 addresses only when an IPv4 address is configured; query for IPv6 addresses only when an IPv6 address is configured. .sp .LP The \fI\fP header shall define the following macros that evaluate to bitwise-distinct integer constants for use in the \fIflags\fP argument to \fIgetnameinfo\fP(): .TP 7 NI_NOFQDN Only the nodename portion of the FQDN is returned for local hosts. .TP 7 NI_NUMERICHOST .sp The numeric form of the node's address is returned instead of its name. .TP 7 NI_NAMEREQD Return an error if the node's name cannot be located in the database. .TP 7 NI_NUMERICSERV .sp The numeric form of the service address is returned instead of its name. .TP 7 NI_NUMERICSCOPE .sp For IPv6 addresses, the numeric form of the scope identifier is returned instead of its name. .TP 7 NI_DGRAM Indicates that the service is a datagram service (SOCK_DGRAM). .sp .SS Address Information Errors .LP The \fI\fP header shall define the following macros for use as error values for \fIgetaddrinfo\fP() and \fIgetnameinfo\fP(): .TP 7 EAI_AGAIN The name could not be resolved at this time. Future attempts may succeed. .TP 7 EAI_BADFLAGS The flags had an invalid value. .TP 7 EAI_FAIL A non-recoverable error occurred. .TP 7 EAI_FAMILY The address family was not recognized or the address length was invalid for the specified family. .TP 7 EAI_MEMORY There was a memory allocation failure. .TP 7 EAI_NONAME The name does not resolve for the supplied parameters. .LP NI_NAMEREQD is set and the host's name cannot be located, or both \fInodename\fP and \fIservname\fP were null. .TP 7 EAI_SERVICE The service passed was not recognized for the specified socket type. .TP 7 EAI_SOCKTYPE The intended socket type was not recognized. .TP 7 EAI_SYSTEM A system error occurred. The error code can be found in \fIerrno\fP. .TP 7 EAI_OVERFLOW .sp An argument buffer overflowed. .sp .LP The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided. .sp .RS .nf \fBvoid endhostent(void); void endnetent(void); void endprotoent(void); void endservent(void); void freeaddrinfo(struct addrinfo *); const char *gai_strerror(int); int getaddrinfo(const char *restrict, const char *restrict, const struct addrinfo *restrict, struct addrinfo **restrict); struct hostent *gethostbyaddr(const void *, socklen_t, int); struct hostent *gethostbyname(const char *); struct hostent *gethostent(void); int getnameinfo(const struct sockaddr *restrict, socklen_t, char *restrict, socklen_t, char *restrict, socklen_t, int); struct netent *getnetbyaddr(uint32_t, int); struct netent *getnetbyname(const char *); struct netent *getnetent(void); struct protoent *getprotobyname(const char *); struct protoent *getprotobynumber(int); struct protoent *getprotoent(void); struct servent *getservbyname(const char *, const char *); struct servent *getservbyport(int, const char *); struct servent *getservent(void); void sethostent(int); void setnetent(int); void setprotoent(int); void setservent(int); \fP .fi .RE .LP The type \fBsocklen_t\fP shall be defined through \fBtypedef\fP as described in \fI\fP. .LP Inclusion of the \fI\fP header may also make visible all symbols from \fI\fP, \fI\fP, and \fI\fP. .LP \fIThe following sections are informative.\fP .SH APPLICATION USAGE .LP None. .SH RATIONALE .LP None. .SH FUTURE DIRECTIONS .LP None. .SH SEE ALSO .LP \fI\fP, \fI\fP, \fI\fP, the System Interfaces volume of IEEE\ Std\ 1003.1-2001, \fIbind\fP(), \fIendhostent\fP(), \fIendnetent\fP(), \fIendprotoent\fP(), \fIendservent\fP(), \fIgetaddrinfo\fP(), \fIgetnameinfo\fP() .SH COPYRIGHT Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .