.\" .\" Copyright (C) 2000, 2001 Internet Software Consortium. .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM .\" DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL .\" INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, .\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING .\" FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, .\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION .\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .TH "LWRES_GETADDRINFO" "3" "Jun 30, 2000" "BIND9" "" .SH NAME lwres_getaddrinfo, lwres_freeaddrinfo \- socket address structure to host and service name .SH SYNOPSIS \fB#include .sp .na int lwres_getaddrinfo(const char *hostname, const char *servname, const struct addrinfo *hints, struct addrinfo **res); .ad .sp .na void lwres_freeaddrinfo(struct addrinfo *ai); .ad \fR.PP If the operating system does not provide a \fBstruct addrinfo\fR, the following structure is used: .sp .nf struct addrinfo { int ai_flags; /* AI_PASSIVE, AI_CANONNAME */ int ai_family; /* PF_xxx */ int ai_socktype; /* SOCK_xxx */ int ai_protocol; /* 0 or IPPROTO_xxx for IPv4 and IPv6 */ size_t ai_addrlen; /* length of ai_addr */ char *ai_canonname; /* canonical name for hostname */ struct sockaddr *ai_addr; /* binary address */ struct addrinfo *ai_next; /* next structure in linked list */ }; .sp .fi .SH "DESCRIPTION" .PP \fBlwres_getaddrinfo()\fR is used to get a list of IP addresses and port numbers for host \fIhostname\fR and service \fIservname\fR. The function is the lightweight resolver's implementation of \fBgetaddrinfo()\fR as defined in RFC2133. \fIhostname\fR and \fIservname\fR are pointers to null-terminated strings or \fBNULL\fR. \fIhostname\fR is either a host name or a numeric host address string: a dotted decimal IPv4 address or an IPv6 address. \fIservname\fR is either a decimal port number or a service name as listed in \fI/etc/services\fR. .PP \fIhints\fR is an optional pointer to a \fBstruct addrinfo\fR. This structure can be used to provide hints concerning the type of socket that the caller supports or wishes to use. The caller can supply the following structure elements in \fI*hints\fR: .TP \fBai_family\fR The protocol family that should be used. When ai_family is set to \fBPF_UNSPEC\fR, it means the caller will accept any protocol family supported by the operating system. .TP \fBai_socktype\fR denotes the type of socket \(em \fBSOCK_STREAM\fR, \fBSOCK_DGRAM\fR or \fBSOCK_RAW\fR \(em that is wanted. When ai_socktype is zero the caller will accept any socket type. .TP \fBai_protocol\fR indicates which transport protocol is wanted: IPPROTO_UDP or IPPROTO_TCP. If ai_protocol is zero the caller will accept any protocol. .TP \fBai_flags\fR Flag bits. If the \fBAI_CANONNAME\fR bit is set, a successful call to \fBlwres_getaddrinfo()\fR will return a a null-terminated string containing the canonical name of the specified hostname in ai_canonname of the first \fBaddrinfo\fR structure returned. Setting the \fBAI_PASSIVE\fR bit indicates that the returned socket address structure is intended for used in a call to \fBbind\fR(2). In this case, if the hostname argument is a \fBNULL\fR pointer, then the IP address portion of the socket address structure will be set to \fBINADDR_ANY\fR for an IPv4 address or \fBIN6ADDR_ANY_INIT\fR for an IPv6 address. When ai_flags does not set the \fBAI_PASSIVE\fR bit, the returned socket address structure will be ready for use in a call to \fBconnect\fR(2) for a connection-oriented protocol or \fBconnect\fR(2), \fBsendto\fR(2), or \fBsendmsg\fR(2) if a connectionless protocol was chosen. The IP address portion of the socket address structure will be set to the loopback address if \fIhostname\fR is a \fBNULL\fR pointer and \fBAI_PASSIVE\fR is not set in ai_flags. If ai_flags is set to \fBAI_NUMERICHOST\fR it indicates that \fIhostname\fR should be treated as a numeric string defining an IPv4 or IPv6 address and no name resolution should be attempted. .PP All other elements of the \fBstruct addrinfo\fR passed via \fIhints\fR must be zero. .PP A \fIhints\fR of \fBNULL\fR is treated as if the caller provided a \fBstruct addrinfo\fR initialized to zero with ai_familyset to PF_UNSPEC. .PP After a successful call to \fBlwres_getaddrinfo()\fR, \fI*res\fR is a pointer to a linked list of one or more \fBaddrinfo\fR structures. Each \fBstruct addrinfo\fR in this list cn be processed by following the ai_next pointer, until a \fBNULL\fR pointer is encountered. The three members ai_family, ai_socktype, and ai_protocol in each returned \fBaddrinfo\fR structure contain the corresponding arguments for a call to \fBsocket\fR(2). For each \fBaddrinfo\fR structure in the list, the ai_addr member points to a filled-in socket address structure of length ai_addrlen. .PP All of the information returned by \fBlwres_getaddrinfo()\fR is dynamically allocated: the addrinfo structures, and the socket address structures and canonical host name strings pointed to by the addrinfostructures. Memory allocated for the dynamically allocated structures created by a successful call to \fBlwres_getaddrinfo()\fR is released by \fBlwres_freeaddrinfo()\fR. \fIai\fR is a pointer to a \fBstruct addrinfo\fR created by a call to \fBlwres_getaddrinfo()\fR. .SH "RETURN VALUES" .PP \fBlwres_getaddrinfo()\fR returns zero on success or one of the error codes listed in \fBgai_strerror\fR(3) if an error occurs. If both \fIhostname\fR and \fIservname\fR are \fBNULL\fR \fBlwres_getaddrinfo()\fR returns EAI_NONAME. .SH "SEE ALSO" .PP \fBlwres\fR(3), \fBlwres_getaddrinfo\fR(3), \fBlwres_freeaddrinfo\fR(3), \fBlwres_gai_strerror\fR(3), \fBRFC2133\fR, \fBgetservbyname\fR(3), \fBbind\fR(2), \fBconnect\fR(2), \fBsendto\fR(2), \fBsendmsg\fR(2), \fBsocket\fR(2).