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| <h5 class="subsubsection">16.6.2.3 Host Address Functions</h5> |
| |
| <p><a name="index-arpa_002finet_002eh-1702"></a>These additional functions for manipulating Internet addresses are |
| declared in the header file <samp><span class="file">arpa/inet.h</span></samp>. They represent Internet |
| addresses in network byte order, and network numbers and |
| local-address-within-network numbers in host byte order. See <a href="Byte-Order.html#Byte-Order">Byte Order</a>, for an explanation of network and host byte order. |
| |
| <!-- arpa/inet.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: int <b>inet_aton</b> (<var>const char *name, struct in_addr *addr</var>)<var><a name="index-inet_005faton-1703"></a></var><br> |
| <blockquote><p>This function converts the IPv4 Internet host address <var>name</var> |
| from the standard numbers-and-dots notation into binary data and stores |
| it in the <code>struct in_addr</code> that <var>addr</var> points to. |
| <code>inet_aton</code> returns nonzero if the address is valid, zero if not. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: uint32_t <b>inet_addr</b> (<var>const char *name</var>)<var><a name="index-inet_005faddr-1704"></a></var><br> |
| <blockquote><p>This function converts the IPv4 Internet host address <var>name</var> from the |
| standard numbers-and-dots notation into binary data. If the input is |
| not valid, <code>inet_addr</code> returns <code>INADDR_NONE</code>. This is an |
| obsolete interface to <code>inet_aton</code>, described immediately above. It |
| is obsolete because <code>INADDR_NONE</code> is a valid address |
| (255.255.255.255), and <code>inet_aton</code> provides a cleaner way to |
| indicate error return. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: uint32_t <b>inet_network</b> (<var>const char *name</var>)<var><a name="index-inet_005fnetwork-1705"></a></var><br> |
| <blockquote><p>This function extracts the network number from the address <var>name</var>, |
| given in the standard numbers-and-dots notation. The returned address is |
| in host order. If the input is not valid, <code>inet_network</code> returns |
| <code>-1</code>. |
| |
| <p>The function works only with traditional IPv4 class A, B and C network |
| types. It doesn't work with classless addresses and shouldn't be used |
| anymore. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: char * <b>inet_ntoa</b> (<var>struct in_addr addr</var>)<var><a name="index-inet_005fntoa-1706"></a></var><br> |
| <blockquote><p>This function converts the IPv4 Internet host address <var>addr</var> to a |
| string in the standard numbers-and-dots notation. The return value is |
| a pointer into a statically-allocated buffer. Subsequent calls will |
| overwrite the same buffer, so you should copy the string if you need |
| to save it. |
| |
| <p>In multi-threaded programs each thread has an own statically-allocated |
| buffer. But still subsequent calls of <code>inet_ntoa</code> in the same |
| thread will overwrite the result of the last call. |
| |
| <p>Instead of <code>inet_ntoa</code> the newer function <code>inet_ntop</code> which is |
| described below should be used since it handles both IPv4 and IPv6 |
| addresses. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: struct in_addr <b>inet_makeaddr</b> (<var>uint32_t net, uint32_t local</var>)<var><a name="index-inet_005fmakeaddr-1707"></a></var><br> |
| <blockquote><p>This function makes an IPv4 Internet host address by combining the network |
| number <var>net</var> with the local-address-within-network number |
| <var>local</var>. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: uint32_t <b>inet_lnaof</b> (<var>struct in_addr addr</var>)<var><a name="index-inet_005flnaof-1708"></a></var><br> |
| <blockquote><p>This function returns the local-address-within-network part of the |
| Internet host address <var>addr</var>. |
| |
| <p>The function works only with traditional IPv4 class A, B and C network |
| types. It doesn't work with classless addresses and shouldn't be used |
| anymore. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: uint32_t <b>inet_netof</b> (<var>struct in_addr addr</var>)<var><a name="index-inet_005fnetof-1709"></a></var><br> |
| <blockquote><p>This function returns the network number part of the Internet host |
| address <var>addr</var>. |
| |
| <p>The function works only with traditional IPv4 class A, B and C network |
| types. It doesn't work with classless addresses and shouldn't be used |
| anymore. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- IPv6 basic API --> |
| <div class="defun"> |
| — Function: int <b>inet_pton</b> (<var>int af, const char *cp, void *buf</var>)<var><a name="index-inet_005fpton-1710"></a></var><br> |
| <blockquote><p>This function converts an Internet address (either IPv4 or IPv6) from |
| presentation (textual) to network (binary) format. <var>af</var> should be |
| either <code>AF_INET</code> or <code>AF_INET6</code>, as appropriate for the type of |
| address being converted. <var>cp</var> is a pointer to the input string, and |
| <var>buf</var> is a pointer to a buffer for the result. It is the caller's |
| responsibility to make sure the buffer is large enough. |
| </p></blockquote></div> |
| |
| <!-- arpa/inet.h --> |
| <!-- IPv6 basic API --> |
| <div class="defun"> |
| — Function: const char * <b>inet_ntop</b> (<var>int af, const void *cp, char *buf, size_t len</var>)<var><a name="index-inet_005fntop-1711"></a></var><br> |
| <blockquote><p>This function converts an Internet address (either IPv4 or IPv6) from |
| network (binary) to presentation (textual) form. <var>af</var> should be |
| either <code>AF_INET</code> or <code>AF_INET6</code>, as appropriate. <var>cp</var> is a |
| pointer to the address to be converted. <var>buf</var> should be a pointer |
| to a buffer to hold the result, and <var>len</var> is the length of this |
| buffer. The return value from the function will be this buffer address. |
| </p></blockquote></div> |
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