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Diffstat (limited to 'lib/libc/net/getaddrinfo.3')
| -rw-r--r-- | lib/libc/net/getaddrinfo.3 | 408 |
1 files changed, 408 insertions, 0 deletions
diff --git a/lib/libc/net/getaddrinfo.3 b/lib/libc/net/getaddrinfo.3 new file mode 100644 index 0000000..39bcdb7 --- /dev/null +++ b/lib/libc/net/getaddrinfo.3 @@ -0,0 +1,408 @@ +.\" Copyright (c) 1983, 1987, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" From: @(#)gethostbyname.3 8.4 (Berkeley) 5/25/95 +.\" $Id: getaddrinfo.3,v 1.3 1999/10/07 08:22:04 jinmei Exp $ +.\" $FreeBSD$ +.\" +.Dd May 25, 1995 +.Dt GETADDRINFO 3 +.Os KAME +.\" +.Sh NAME +.Nm getaddrinfo +.Nm freeaddrinfo , +.Nm gai_strerror +.Nd nodename-to-address translation in protocol-independent manner +.\" +.Sh SYNOPSIS +.Fd #include <sys/socket.h> +.Fd #include <netdb.h> +.Ft int +.Fn getaddrinfo "const char *nodename" "const char *servname" \ +"const struct addrinfo *hints" "struct addrinfo **res" +.Ft void +.Fn freeaddrinfo "struct addrinfo *ai" +.Ft "char *" +.Fn gai_strerror "int ecode" +.\" +.Sh DESCRIPTION +The +.Fn getaddrinfo +function is defined for protocol-independent nodename-to-address translation. +It performs functionality of +.Xr gethostbyname 3 +and +.Xr getservbyname 3 , +in more sophisticated manner. +.Pp +The addrinfo structure is defined as a result of including the +.Li <netdb.h> +header: +.Bd -literal -offset +struct addrinfo { * + int ai_flags; /* AI_PASSIVE, AI_CANONNAME, AI_NUMERICHOST */ + 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 nodename */ + struct sockaddr *ai_addr; /* binary address */ + struct addrinfo *ai_next; /* next structure in linked list */ +}; +.Ed +.Pp +The +.Fa nodename +and +.Fa servname +arguments are pointers to null-terminated strings or +.Dv NULL . +One or both of these two arguments must be a +.Pf non Dv -NULL +pointer. +In the normal client scenario, both the +.Fa nodename +and +.Fa servname +are specified. +In the normal server scenario, only the +.Fa servname +is specified. +A +.Pf non Dv -NULL +.Fa nodename +string can be either a node name or a numeric host address string +.Po +i.e., a dotted-decimal IPv4 address or an IPv6 hex address +.Pc . +A +.Pf non Dv -NULL +.Fa servname +string can be either a service name or a decimal port number. +.Pp +The caller can optionally pass an +.Li addrinfo +structure, pointed to by the third argument, +to provide hints concerning the type of socket that the caller supports. +In this +.Fa hints +structure all members other than +.Fa ai_flags , +.Fa ai_family , +.Fa ai_socktype , +and +.Fa ai_protocol +must be zero or a +.Dv NULL +pointer. +A value of +.Dv PF_UNSPEC +for +.Fa ai_family +means the caller will accept any protocol family. +A value of 0 for +.Fa ai_socktype +means the caller will accept any socket type. +A value of 0 for +.Fa ai_protocol +means the caller will accept any protocol. +For example, if the caller handles only TCP and not UDP, then the +.Fa ai_socktype +member of the hints structure should be set to +.Dv SOCK_STREAM +when +.Fn getaddrinfo +is called. +If the caller handles only IPv4 and not IPv6, then the +.Fa ai_family +member of the +.Fa hints +structure should be set to +.Dv PF_INET +when +.Fn getaddrinfo +is called. +If the third argument to +.Fn getaddrinfo +is a +.Dv NULL +pointer, this is the same as if the caller had filled in an +.Li addrinfo +structure initialized to zero with +.Fa ai_family +set to PF_UNSPEC. +.Pp +Upon successful return a pointer to a linked list of one or more +.Li addrinfo +structures is returned through the final argument. +The caller can process each +.Li addrinfo +structure in this list by following the +.Fa ai_next +pointer, until a +.Dv NULL +pointer is encountered. +In each returned +.Li addrinfo +structure the three members +.Fa ai_family , +.Fa ai_socktype , +and +.Fa ai_protocol +are the corresponding arguments for a call to the +.Fn socket +function. +In each +.Li addrinfo +structure the +.Fa ai_addr +member points to a filled-in socket address structure whose length is +specified by the +.Fa ai_addrlen +member. +.Pp +If the +.Dv AI_PASSIVE +bit is set in the +.Fa ai_flags +member of the +.Fa hints +structure, then the caller plans to use the returned socket address +structure in a call to +.Fn bind . +In this case, if the +.Fa nodename +argument is a +.Dv NULL +pointer, then the IP address portion of the socket +address structure will be set to +.Dv INADDR_ANY +for an IPv4 address or +.Dv IN6ADDR_ANY_INIT +for an IPv6 address. +.Pp +If the +.Dv AI_PASSIVE +bit is not set in the +.Fa ai_flags +member of the +.Fa hints +structure, then the returned socket address structure will be ready for a +call to +.Fn connect +.Pq for a connection-oriented protocol +or either +.Fn connect , +.Fn sendto , or +.Fn sendmsg +.Pq for a connectionless protocol . +In this case, if the +.Fa nodename +argument is a +.Dv NULL +pointer, then the IP address portion of the +socket address structure will be set to the loopback address. +.Pp +If the +.Dv AI_CANONNAME +bit is set in the +.Fa ai_flags +member of the +.Fa hints +structure, then upon successful return the +.Fa ai_canonname +member of the first +.Li addrinfo +structure in the linked list will point to a null-terminated string +containing the canonical name of the specified +.Fa nodename . +.Pp +If the +.Dv AI_NUMERICHOST +bit is set in the +.Fa ai_flags +member of the +.Fa hints +structure, then a +.Pf non Dv -NULL +.Fa nodename +string must be a numeric host address string. +Otherwise an error of +.Dv EAI_NONAME +is returned. +This flag prevents any type of name resolution service (e.g., the DNS) +from being called. +.Pp +All of the information returned by +.Fn getaddrinfo +is dynamically allocated: +the +.Li addrinfo +structures, and the socket address structures and canonical node name +strings pointed to by the addrinfo structures. +To return this information to the system the function +.Fn freeaddrinfo +is called. +The +.Fa addrinfo +structure pointed to by the +.Fa ai argument +is freed, along with any dynamic storage pointed to by the structure. +This operation is repeated until a +.Dv NULL +.Fa ai_next +pointer is encountered. +.Pp +To aid applications in printing error messages based on the +.Dv EAI_xxx +codes returned by +.Fn getaddrinfo , +.Fn gai_strerror +is defined. +The argument is one of the +.Dv EAI_xxx +values defined earlier and the return value points to a string describing +the error. +If the argument is not one of the +.Dv EAI_xxx +values, the function still returns a pointer to a string whose contents +indicate an unknown error. +.\" +.Sh EXTENSION +The implementation allows experimental numeric IPv6 address notation with +scope identifier. +By appending atmark and scope identifier to addresses, you can fill +.Li sin6_scope_id +field for addresses. +This would make management of scoped address easier, +and allows cut-and-paste input of scoped address. +.Pp +At this moment the code supports only link-local addresses with the format. +Scope identifier is hardcoded to name of hardware interface associated +with the link. +.Po +such as +.Li ne0 +.Pc . +Example would be like +.Dq Li fe80::1@ne0 , +which means +.Do +.Li fe80::1 +on the link associated with +.Li ne0 +interface +.Dc . +.Pp +The implementation is still very experimental and non-standard. +The current implementation assumes one-by-one relationship between +interface and link, which is not necessarily true from the specification. +.\" +.Sh FILES +.Bl -tag -width /etc/resolv.conf -compact +.It Pa /etc/hosts +.It Pa /etc/host.conf +.It Pa /etc/resolv.conf +.El +.\" +.Sh DIAGNOSTICS +Error return status from +.Fn getaddrinfo +is zero on success and non-zero on errors. +Non-zero error codes are defined in +.Li <netdb.h> , +and as follows: +.Pp +.Bl -tag -width EAI_ADDRFAMILY -compact +.It Dv EAI_ADDRFAMILY +address family for nodename not supported +.It Dv EAI_AGAIN +temporary failure in name resolution +.It Dv EAI_BADFLAGS +invalid value for ai_flags +.It Dv EAI_FAIL +non-recoverable failure in name resolution +.It Dv EAI_FAMILY +ai_family not supported +.It Dv EAI_MEMORY +memory allocation failure +.It Dv EAI_NODATA +no address associated with nodename +.It Dv EAI_NONAME +nodename nor servname provided, or not known +.It Dv EAI_SERVICE +servname not supported for ai_socktype +.It Dv EAI_SOCKTYPE +ai_socktype not supported +.It Dv EAI_SYSTEM +system error returned in errno +.El +.Pp +If called with proper argument, +.Fn gai_strerror +returns a pointer to a string describing the given error code. +If the argument is not one of the +.Dv EAI_xxx +values, the function still returns a pointer to a string whose contents +indicate an unknown error. +.\" +.Sh SEE ALSO +.Xr getnameinfo 3 , +.Xr gethostbyname 3 , +.Xr getservbyname 3 , +.Xr hosts 5 , +.Xr services 5 , +.Xr hostname 7 , +.Xr named 8 . +.Pp +.Rs +.%A R. Gilligan +.%A S. Thomson +.%A J. Bound +.%A W. Stevens +.%T Basic Socket Interface Extensions for IPv6 +.%R RFC2553 +.%D March 1999 +.Re +.\" +.Sh HISTORY +The implementation first appeared in WIDE Hydrangea IPv6 protocol stack kit. +.\" +.Sh STANDARDS +The +.Fn getaddrinfo +function is defined IEEE POSIX 1003.1g draft specification, +and documented in ``Basic Socket Interface Extensions for IPv6'' +.Pq RFC2533 . +.\" +.Sh BUGS +The text was shamelessly copied from RFC2553. |
