+++ /dev/null
-<!-- Copyright (C) 2003 Red Hat, Inc. -->
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-<HTML
-><HEAD
-><TITLE
->Sockets</TITLE
-><meta name="MSSmartTagsPreventParsing" content="TRUE">
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-TITLE="eCos Reference Manual"
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-REL="UP"
-TITLE="File System Support Infrastructure"
-HREF="fileio.html"><LINK
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-TITLE="Initialization and Mounting"
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-><DIV
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-><H1
-><A
-NAME="FILEIO-SOCKETS">Chapter 26. Sockets</H1
-><P
->If a network stack is present, then the FILEIO infrastructure also
-provides access to the standard BSD socket calls.</P
-><P
->The netstack table contains entries which describe the network
-protocol stacks that are in the system image. Each resident stack
-should export an entry to this table using the
-<TT
-CLASS="LITERAL"
->NSTAB_ENTRY()</TT
-> macro.</P
-><P
->Each table entry has the following structure:</P
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->struct cyg_nstab_entry
-{
- cyg_bool valid; // true if stack initialized
- cyg_uint32 syncmode; // synchronization protocol
- char *name; // stack name
- char *devname; // hardware device name
- CYG_ADDRWORD data; // private data value
-
- int (*init)( cyg_nstab_entry *nste );
- int (*socket)( cyg_nstab_entry *nste, int domain, int type,
- int protocol, cyg_file *file );
-};</PRE
-></TD
-></TR
-></TABLE
-><P
->This table is analogous to a combination of the filesystem and mount
-tables.</P
-><P
->The <TT
-CLASS="STRUCTFIELD"
-><I
->valid</I
-></TT
-> field is set
-<TT
-CLASS="LITERAL"
->true</TT
-> if the stack's <TT
-CLASS="FUNCTION"
->init()</TT
->
-function returned successfully and the
-<TT
-CLASS="STRUCTFIELD"
-><I
->syncmode</I
-></TT
-> field contains the
-<TT
-CLASS="LITERAL"
->CYG_SYNCMODE_SOCK_*</TT
-> bits described above.</P
-><P
->The <TT
-CLASS="STRUCTFIELD"
-><I
->name</I
-></TT
-> field contains the name of the
-protocol stack.</P
-><P
->The <TT
-CLASS="STRUCTFIELD"
-><I
->devname</I
-></TT
-> field names the device that the stack is using. This may
-reference a device under "/dev", or may be a name that is only
-meaningful to the stack itself.</P
-><P
->The <TT
-CLASS="FUNCTION"
->init()</TT
-> function pointer is called during
-system initialization to start the protocol stack running. If it
-returns non-zero the <TT
-CLASS="STRUCTFIELD"
-><I
->valid</I
-></TT
-> field is set
-false and the stack will be ignored subsequently.</P
-><P
->The <TT
-CLASS="FUNCTION"
->socket()</TT
-> function is called to attempt to create a socket in the
-stack. When the <TT
-CLASS="FUNCTION"
->socket()</TT
-> API function is called the netstack table is
-scanned and for each valid entry the <TT
-CLASS="FUNCTION"
->socket()</TT
->
-function pointer is called. If
-this returns non-zero then the scan continues to the next valid stack,
-or terminates with an error if the end of the table is reached.</P
-><P
->The result of a successful socket call is an initialized file object
-with the <TT
-CLASS="STRUCTFIELD"
-><I
->f_xops</I
-></TT
-> field pointing to the
-following structure:</P
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->struct cyg_sock_ops
-{
- int (*bind) ( cyg_file *fp, const sockaddr *sa, socklen_t len );
- int (*connect) ( cyg_file *fp, const sockaddr *sa, socklen_t len );
- int (*accept) ( cyg_file *fp, cyg_file *new_fp,
- struct sockaddr *name, socklen_t *anamelen );
- int (*listen) ( cyg_file *fp, int len );
- int (*getname) ( cyg_file *fp, sockaddr *sa, socklen_t *len, int peer );
- int (*shutdown) ( cyg_file *fp, int flags );
- int (*getsockopt)( cyg_file *fp, int level, int optname,
- void *optval, socklen_t *optlen);
- int (*setsockopt)( cyg_file *fp, int level, int optname,
- const void *optval, socklen_t optlen);
- int (*sendmsg) ( cyg_file *fp, const struct msghdr *m,
- int flags, ssize_t *retsize );
- int (*recvmsg) ( cyg_file *fp, struct msghdr *m,
- socklen_t *namelen, ssize_t *retsize );
-};</PRE
-></TD
-></TR
-></TABLE
-><P
->It should be obvious from the names of these functions which API calls
-they provide support for. The <TT
-CLASS="FUNCTION"
->getname()</TT
-> function
-pointer provides support for both <TT
-CLASS="FUNCTION"
->getsockname()</TT
->
-and <TT
-CLASS="FUNCTION"
->getpeername()</TT
-> while the
-<TT
-CLASS="FUNCTION"
->sendmsg()</TT
-> and <TT
-CLASS="FUNCTION"
->recvmsg()</TT
->
-function pointers provide support for <TT
-CLASS="FUNCTION"
->send()</TT
->,
-<TT
-CLASS="FUNCTION"
->sendto()</TT
->, <TT
-CLASS="FUNCTION"
->sendmsg()</TT
->,
-<TT
-CLASS="FUNCTION"
->recv()</TT
->, <TT
-CLASS="FUNCTION"
->recvfrom()</TT
-> and
-<TT
-CLASS="FUNCTION"
->recvmsg()</TT
-> as appropriate.</P
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