55 Network Utilities

This chapter describes network utilities provided in the module NetSocket.c. These utilities are convenience functions that you can use in place of net library functions in applications that use the net library. You can find NetSocket.c in the folder Libraries\Net\Src. (On Palm OS^® 3.5, NetSocket.c is in the folder CodeWarrior Libraries\Comms\NetSocket\Src.)

The include file for the functions described in this chapter is <unix/sys_socket.h>. This header file is not included by any other Palm header file; you must explicitly include it in your code.

For more information on NetSocket.c and sys_socket.h, see the chapter "Network Communication" in the Palm OS Programmer's Companion.

Network Utility Functions

NetUReadN

Purpose

Reads a specified number of bytes from a socket.

Prototype

Int32 NetUReadN (NetSocketRef fd, UInt8* bufP, UInt32 numBytes)

Parameters

-> fd

Descriptor for the open socket.

<- bufP

Pointer to buffer to hold received data.

-> numBytes

Number of bytes to read.

Result

Returns the number of bytes actually read. If the return value is less than 0, an error occurred.

Comments

This function repeatedly calls NetLibReceive until numBytes have been read or until NetLibReceive returns an error.

See Also

NetUWriteN

NetUTCPOpen

Purpose

Opens a TCP (streams-based) socket and connects it to a server.

Prototype

NetSocketRef NetUTCPOpen (Char* hostName, Char* serviceName, Int16 port)

Parameters

-> hostName

Remote host, given either by name or by dotted decimal address.

-> serviceName

The name of a network service or NULL if the port parameter is used. Possible services are "echo", "discard", "daytime", "qotd", "chargen", "ftp-data", "ftp", "telnet", "smtp", "time", "name", "finger", "pop2", "pop3", "nntp", "imap2".

-> port

The number of the port to connect to on the remote host. Ignored if serviceName is not NULL.

Result

Returns the socket descriptor of the socket that was connected, or -1 if an error occurred.

Comments

If serviceName is given, this function looks up the port number for that service on the remote host and uses it for the connection.

This function is the equivalent of calling NetLibSocketOpen and NetLibSocketConnect (or socket and connect).

---

NOTE:  

This function does not return specific reasons for failure if there is a failure. This function is not production-quality code. It is provided as a quick and dirty way of creating a connection and as sample code that can be used as a reference.

---

NetUWriteN

Purpose

Writes the specified number of bytes to a socket.

Prototype

Int32 NetUWriteN (NetSocketRef fd, UInt8* bufP, UInt32 numBytes)

Parameters

-> fd

Descriptor for the open socket.

-> bufP

Pointer to buffer to write.

-> numBytes

Number of bytes to write.

Result

Returns the number of bytes actually sent. If the return value is less than 0, an error occurred.

Comments

This function repeatedly calls NetLibSend until numBytes have been written or until NetLibSend returns an error.

See Also

NetUReadN