Translation

(itstool) path: sect4/para
English
So far, we have viewed <varname>sockaddr</varname> as an abstraction. Our computer does not store <varname>short</varname> integers as a single 16-bit entity, but as a sequence of 2 bytes. Similarly, it stores 32-bit integers as a sequence of 4 bytes.
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Context English Portuguese (Brazil) State
Specifically, whenever the <emphasis>address family</emphasis> is <symbol>AF_INET</symbol>, we can use <varname>struct sockaddr_in</varname> found in <filename>netinet/in.h</filename>, wherever <varname>sockaddr</varname> is expected: Especificamente, sempre que o <emphasis> família de endereço </emphasis> é <symbol> AF_INET </symbol> , podemos usar <varname> struct sockaddr_in </varname> encontrado em <filename> netinet / in.h </filename> onde quer que <varname> sockaddr </varname> é esperado:
/*
* Socket address, internet style.
*/
struct sockaddr_in {
uint8_t sin_len;
sa_family_t sin_family;
in_port_t sin_port;
struct in_addr sin_addr;
char sin_zero[8];
}; 		/*
* Socket address, internet style.
*/
struct sockaddr_in {
uint8_t sin_len;
sa_family_t sin_family;
in_port_t sin_port;
struct in_addr sin_addr;
char sin_zero[8];
};
We can visualize its organization this way: Podemos visualizar sua organização desta maneira:
_ external ref='sockets/sain' md5='__failed__' external ref='sockets/sain' md5='__failed__'
0 1 2 3
+--------+--------+-----------------+
0 | 0 | Family | Port |
+--------+--------+-----------------+
4 | IP Address |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+ 		0 1 2 3
+--------+--------+-----------------+
0 | 0 | Family | Port |
+--------+--------+-----------------+
4 | IP Address |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+
<imageobject> <imagedata fileref="sockets/sain"/> </imageobject> <textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>sockaddr_in</phrase> </textobject> <imageobject><imagedata fileref="sockets/sain"/></imageobject><textobject> &lt;_: literallayout-1 /&gt; </textobject><textobject><phrase> sockaddr_in </phrase></textobject>
The three important fields are <varname>sin_family</varname>, which is byte 1 of the structure, <varname>sin_port</varname>, a 16-bit value found in bytes 2 and 3, and <varname>sin_addr</varname>, a 32-bit integer representation of the <acronym>IP</acronym> address, stored in bytes 4-7. Os três campos importantes são <varname> sin_family </varname> , que é o byte 1 da estrutura, <varname> sin_port </varname> , um valor de 16 bits encontrado nos bytes 2 e 3 e <varname> sin_addr </varname> , uma representação inteira de 32 bits do endereço <acronym>IP</acronym> , armazenada nos bytes 4-7.
Now, let us try to fill it out. Let us assume we are trying to write a client for the <emphasis>daytime</emphasis> protocol, which simply states that its server will write a text string representing the current date and time to port 13. We want to use <acronym>TCP/IP</acronym>, so we need to specify <constant>AF_INET</constant> in the address family field. <constant>AF_INET</constant> is defined as <constant>2</constant>. Let us use the <acronym>IP</acronym> address of <systemitem class="ipaddress">192.43.244.18</systemitem>, which is the time server of US federal government (<systemitem class="fqdomainname">time.nist.gov</systemitem>). Agora, vamos tentar preenchê-lo. Vamos supor que estamos tentando escrever um cliente para o <emphasis> dia </emphasis> protocolo, que simplesmente afirma que seu servidor irá escrever uma seqüência de texto que representa a data e hora atuais para a porta 13. Queremos usar <acronym>TCP / IP</acronym> , por isso precisamos especificar <constant> AF_INET </constant> no campo da família de endereços. <constant> AF_INET </constant> é definido como <constant> 2 </constant> . Vamos usar o endereço <acronym>IP</acronym> de <systemitem class="ipaddress"> 192.43.244.18 </systemitem> , que é o servidor de horário do governo federal dos EUA ( <systemitem class="fqdomainname"> time.nist.gov </systemitem> )
_ external ref='sockets/sainfill' md5='__failed__' external ref='sockets/sainfill' md5='__failed__'
0 1 2 3
+--------+--------+-----------------+
0 | 0 | 2 | 13 |
+-----------------+-----------------+
4 | 192.43.244.18 |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+ 		0 1 2 3
+--------+--------+-----------------+
0 | 0 | 2 | 13 |
+-----------------+-----------------+
4 | 192.43.244.18 |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+
<imageobject> <imagedata fileref="sockets/sainfill"/> </imageobject> <textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>Specific example of sockaddr_in</phrase> </textobject> <imageobject><imagedata fileref="sockets/sainfill"/></imageobject><textobject> &lt;_: literallayout-1 /&gt; </textobject><textobject><phrase> Exemplo específico de sockaddr_in </phrase></textobject>
By the way the <varname>sin_addr</varname> field is declared as being of the <varname>struct in_addr</varname> type, which is defined in <filename>netinet/in.h</filename>: A propósito, o <varname> sin_addr </varname> campo é declarado como sendo do <varname> struct in_addr </varname> tipo, que é definido em <filename> netinet / in.h </filename> :
/*
* Internet address (a structure for historical reasons)
*/
struct in_addr {
in_addr_t s_addr;
}; 		/*
* Internet address (a structure for historical reasons)
*/
struct in_addr {
in_addr_t s_addr;
};
In addition, <varname>in_addr_t</varname> is a 32-bit integer. Além do que, além do mais, <varname> in_addr_t </varname> é um inteiro de 32 bits.
The <systemitem class="ipaddress">192.43.244.18</systemitem> is just a convenient notation of expressing a 32-bit integer by listing all of its 8-bit bytes, starting with the <emphasis>most significant</emphasis> one. O <systemitem class="ipaddress"> 192.43.244.18 </systemitem> é apenas uma notação conveniente de expressar um inteiro de 32 bits, listando todos os seus bytes de 8 bits, começando com o <emphasis> mais significante </emphasis> 1.
So far, we have viewed <varname>sockaddr</varname> as an abstraction. Our computer does not store <varname>short</varname> integers as a single 16-bit entity, but as a sequence of 2 bytes. Similarly, it stores 32-bit integers as a sequence of 4 bytes. Até agora, vimos <varname> sockaddr </varname> como uma abstração. Nosso computador não armazena <varname> curto </varname> inteiros como uma única entidade de 16 bits, mas como uma sequência de 2 bytes. Da mesma forma, armazena números inteiros de 32 bits como uma seqüência de 4 bytes.
Suppose we coded something like this: Suponha que codificássemos algo assim:
sa.sin_family = AF_INET;
sa.sin_port = 13;
sa.sin_addr.s_addr = (((((192 &lt;&lt; 8) | 43) &lt;&lt; 8) | 244) &lt;&lt; 8) | 18; 		sa.sin_family = AF_INET;
sa.sin_port = 13;
sa.sin_addr.s_addr = (((((192 &lt;&lt; 8) | 43) &lt;&lt; 8) | 244) &lt;&lt; 8) | 18;
What would the result look like? Como seria o resultado?
Well, that depends, of course. On a <trademark class="registered">Pentium</trademark>, or other x86, based computer, it would look like this: Bem, isso depende, claro. Em um <trademark class="registered"> Pentium </trademark> , ou outro computador baseado em x86, ficaria assim:
_ external ref='sockets/sainlsb' md5='__failed__' external ref='sockets/sainlsb' md5='__failed__'
0 1 2 3
+--------+--------+--------+--------+
0 | 0 | 2 | 13 | 0 |
+--------+--------+--------+--------+
4 | 18 | 244 | 43 | 192 |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+ 		0 1 2 3
+--------+--------+--------+--------+
0 | 0 | 2 | 13 | 0 |
+--------+--------+--------+--------+
4 | 18 | 244 | 43 | 192 |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+
<imageobject> <imagedata fileref="sockets/sainlsb"/> </imageobject> <textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>sockaddr_in on an Intel system</phrase> </textobject> <imageobject><imagedata fileref="sockets/sainlsb"/></imageobject><textobject> &lt;_: literallayout-1 /&gt; </textobject><textobject><phrase> sockaddr_in em um sistema Intel </phrase></textobject>
On a different system, it might look like this: Em um sistema diferente, pode ser assim:
_ external ref='sockets/sainmsb' md5='__failed__' external ref='sockets/sainmsb' md5='__failed__'
0 1 2 3
+--------+--------+--------+--------+
0 | 0 | 2 | 0 | 13 |
+--------+--------+--------+--------+
4 | 192 | 43 | 244 | 18 |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+ 		0 1 2 3
+--------+--------+--------+--------+
0 | 0 | 2 | 0 | 13 |
+--------+--------+--------+--------+
4 | 192 | 43 | 244 | 18 |
+-----------------------------------+
8 | 0 |
+-----------------------------------+
12 | 0 |
+-----------------------------------+
<imageobject> <imagedata fileref="sockets/sainmsb"/> </imageobject> <textobject> <_:literallayout-1/> </textobject> <textobject> <phrase>sockaddr_in on an MSB system</phrase> </textobject> <imageobject><imagedata fileref="sockets/sainmsb"/></imageobject><textobject> &lt;_: literallayout-1 /&gt; </textobject><textobject><phrase> sockaddr_in em um sistema MSB </phrase></textobject>
And on a PDP it might look different yet. But the above two are the most common ways in use today. E em um PDP pode parecer diferente ainda. Mas os dois acima são as formas mais comuns em uso hoje.
Ordinarily, wanting to write portable code, programmers pretend that these differences do not exist. And they get away with it (except when they code in assembly language). Alas, you cannot get away with it that easily when coding for sockets. Normalmente, querendo escrever códigos portáveis, os programadores fingem que essas diferenças não existem. E eles se safam (exceto quando eles codificam na linguagem assembly). Infelizmente, você não pode se safar tão facilmente quando codifica para sockets.
Why? Por quê?
Because when communicating with another computer, you usually do not know whether it stores data <emphasis>most significant byte</emphasis> (<acronym>MSB</acronym>) or <emphasis>least significant byte</emphasis> (<acronym>LSB</acronym>) first. Porque quando se comunica com outro computador, você geralmente não sabe se ele armazena dados <emphasis> byte mais significativo </emphasis> ( <acronym>MSB</acronym> ) ou <emphasis> byte menos significativo </emphasis> ( <acronym>LSB</acronym> ) primeiro.

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(itstool) path: sect4/para
Source string location
book.translate.xml:5541
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a year ago
Source string age
a year ago
Translation file
books/pt_BR/developers-handbook.po, string 919