blocks|key|2338409|text|“已接收”行使用的格式在RFC2821中定义，正则表达式无法解析它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2338410|(您无论如何都可以尝试，对于已知软件生成的一个有限的标头子集，您可能会成功，但当您将其附加到在现实世界邮件中发现的一系列奇怪的东西时，它将失败。)|2338411|使用现有的RFC2821解析器，您应该可以，但否则，您应该会失败，并编写软件来处理它。不要以任何重要的东西为基础，比如围绕它的安全系统。|2338412|2338413|我们需要提取"by“服务器。|blockquote|2338414|2338415|2338416|‘'from’更有可能是有用的。“by”行中给出的主机名是由主机本身看到的，因此不能保证它将是可公开解析的FQDN。当然，您并不倾向于在那里获得有效的(TCP-Info)。|2338417|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|T|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|U|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|V|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|W|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|O|$]]

The format used by 'Received' lines is defined in RFC 2821, and regex can't parse it.

(You can try anyway, and for a limited subset of headers produced by known software you might succeed, but when you attach this to the range of strange stuff found in real-world mail it will fail.)

Use an existing RFC 2821 parser and you should be OK, but otherwise you should expect failure, and write the software to cope with it. Don't base anything important like a security system around it.

<blockquote>
 We need to extract the "by" server.
</blockquote>

'from' is more likely to be of use. The hostname given in a 'by' line is as seen by the host itself, so there is no guarantee it will be a publically resolvable FQDN. And of course you don't tend to get valid (TCP-Info) there.

blocks|key|5549726|text|有一个Perl+Received+module，它是SpamAssassin代码的分支。它返回带有相关信息的Received报头的散列。例如|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5549727|{+ip+=>+'64.12.136.4',+
++id+=>+'875522',+
++by+=>+'xxx.com',
++helo+=>+'imo-m01.mx.aol.com'+}|code-block|syntax|javascript|5549728|entityMap|0|LINK|mutability|MUTABLE|url|http://search.cpan.org/~simon/Email-Received-1.00/lib/Email/Received.pm^0|1I|8|8|F|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

There is a Perl <a href="http://search.cpan.org/~simon/Email-Received-1.00/lib/Email/Received.pm" rel="nofollow">Received module</a> which is a fork of the SpamAssassin code. It returns a hash for a <code>Received</code> header with the relevant information. For example 

<pre><code>{ ip =&gt; '64.12.136.4', 
 id =&gt; '875522', 
 by =&gt; 'xxx.com',
 helo =&gt; 'imo-m01.mx.aol.com' }
</code></pre>

blocks|key|5549657|text|vmime应该很好，任何邮件库都可以让你这么做。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|5549658|entityMap|0|LINK|mutability|MUTABLE|url|http://www.vmime.org/^0|0|5|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

<a href="http://www.vmime.org/" rel="nofollow noreferrer">vmime</a> should be fine, moreless any mail library will allow you to do that.

blocks|key|423605|text|您可能希望使用正则表达式|type|unstyled|depth|inlineStyleRanges|entityRanges|data|423606|(?<=by).*(?=with)|423607|这将得到pilot01.cl.msu.edu+(8.10.2/8.10.2)|423608|编辑:我发现有趣的是，当它实际上得到了OP所要求的东西时，它被降级了。|423609|C#：|423610|string+header+=+"Received:+from+server.mymailhost.com+(mail.mymailhost.com+[126.43.75.123])+by+pilot01.cl.msu.edu+(8.10.2/8.10.2)+with+ESMTP+id+NAA23597;+Fri,+12+Jul+2002+16:11:20+-0400+(EDT)";
+++++++System.Text.RegularExpressions.Regex+r+=+new+System.Text.RegularExpressions.Regex(@"(?<=by).*(?=with)");
+++++++System.Text.RegularExpressions.Match+m+=+r.Match(header);
+++++++Console.WriteLine(m.Captures[0].Value);
+++++++Console.ReadKey();|code-block|syntax|javascript|423611|我没有声称它是完整的，但我想知道给它一个-1的人是否尝试过。嗯..。|423612|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|X|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

You'll want to use Regular Expressions possibly

(?&lt;=by).*(?=with)

This will give you pilot01.cl.msu.edu (8.10.2/8.10.2) 

Edit:
I find it amusing that this was modded down when it actually gets what the OP asked for.

C#:

<pre><code>string header = "Received: from server.mymailhost.com (mail.mymailhost.com [126.43.75.123]) by pilot01.cl.msu.edu (8.10.2/8.10.2) with ESMTP id NAA23597; Fri, 12 Jul 2002 16:11:20 -0400 (EDT)";
 System.Text.RegularExpressions.Regex r = new System.Text.RegularExpressions.Regex(@"(?&lt;=by).*(?=with)");
 System.Text.RegularExpressions.Match m = r.Match(header);
 Console.WriteLine(m.Captures[0].Value);
 Console.ReadKey();
</code></pre>

I didnt claim that it was complete, but am wondering if the person that gave it a -1 even tried. Meh..

blocks|key|2338392|text|您可以使用正则表达式。它看起来像这样(未经过测试)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2338393|#include+<regex.h>

regex_t+*re+=+malloc(sizeof(regex_t));

const+char+*restr+=+"by+([A-Za-z.]%2B)+$([%5E$]*)\)";

check(regcomp(re,+restr,+REG_EXTENDED+%7C+REG_ICASE),+"regcomp");

size_t+nmatch+=+1;

regmatch_t+*matches+=+malloc(sizeof(regmatch_t)+*+nmatch);

int+ret+=+regexec(re,+YOUR_STRING,+nmatch,+matches,+0);

check(ret+!=+0,+"regexec");

int+size;

size+=+matches[2].rm_eo+-+matches[2].rm_so;
char+*host+=+malloc(sizeof(char)+*+size);
strncpy(host,+YOUR_STRING+%2B+matches[2].rm_so,+size+);
host[size]+=+'\0';

size+=+matches[3].rm_eo+-+matches[3].rm_so;
char+*ip+=+malloc(sizeof(char)+*+size);
strncpy(ip,+YOUR_STRING+%2B+matches[3].rm_so,+size+);
ip[size]+=+'\0';|code-block|syntax|javascript|2338394|check是一个宏，可以帮助您找出是否存在任何问题：|2338395|#define+check(condition,+description)+if+(condition)+{+fprintf(stdout,+"%25s:%25i+-+%25s+-+%25s\n",+__FILE__,+__LINE__,+description,+strerror(errno));+exit(1);+}|2338396|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can use regular expressions. It would look like this(not tested):

<pre><code>#include &lt;regex.h&gt;

regex_t *re = malloc(sizeof(regex_t));

const char *restr = "by ([A-Za-z.]+) $([^$]*)\)";

check(regcomp(re, restr, REG_EXTENDED | REG_ICASE), "regcomp");

size_t nmatch = 1;

regmatch_t *matches = malloc(sizeof(regmatch_t) * nmatch);

int ret = regexec(re, YOUR_STRING, nmatch, matches, 0);

check(ret != 0, "regexec");

int size;

size = matches[2].rm_eo - matches[2].rm_so;
char *host = malloc(sizeof(char) * size);
strncpy(host, YOUR_STRING + matches[2].rm_so, size );
host[size] = '\0';

size = matches[3].rm_eo - matches[3].rm_so;
char *ip = malloc(sizeof(char) * size);
strncpy(ip, YOUR_STRING + matches[3].rm_so, size );
ip[size] = '\0';
</code></pre>

check is a macro to help you figure out if there are any problems:

<pre><code>#define check(condition, description) if (condition) { fprintf(stdout, "%s:%i - %s - %s\n", __FILE__, __LINE__, description, strerror(errno)); exit(1); }
</code></pre>

blocks|key|3437855|text|typedef+struct+mailHeaders{
++++char+name[100];
++++char+value[2000];
}mailHeaders;

int+header_count+=+0;
mailHeaders+headers[30];++++//+A+struct+to+hold+the+name+value+pairs

char+*GetMailHeader(char+*name)
{
++++char+*value+=+NULL;;
++++int+i;

++++for(i=0;i<header_count;i%2B%2B){
++++++++if(strcmp(name,headers[i].name)+==+0){
++++++++++++value+=+headers[i].value;
++++++++++++break;
++++++++}
++++}
++++return(value);
}


void+ReadMail(void)
{

++++//Loop+through+the+email+message+line+by+line+to+separate+the+headers.++Then+save+the+name+value+pairs+to+a+linked+list+or+struct.++
++++++++++char+*Received+=+NULL+//+Received+header
++++char+*mail+=+NULL;++//+Buffer+that+has+the+email+message.
++++char+*line+=+NULL;++//+A+line+of+text+in+the+email.+
++++char+*name+=+NULL;++//+Header+name
++++char+*value+=+NULL;+//+Header+value

++++int+index+=+-1;+++++//+Header+index


++++memset(&headers,'\0',sizeof(mailHeaders));

++++line+=+strtok(mail,"\n");
++++while(line+!=+NULL)
++++{

++++++++if(*line+==+'\t')+//+Tabbed+headers
++++++++{
++++++++++++strcat(headers[index].value,line);+//+Concatenate+the+tabbed+values
++++++++}
++++++++else
++++++++{
++++++++++++name+=+line;++
++++++++++++value+=+strchr(line,':');++//+Split+the+name+value+pairs.++
++++++++++++if(value+!=+NULL)
++++++++++++{
++++++++++++++++*value='\0';++++//+NULL+the+colon+
++++++++++++++++value%2B%2B;++++++++//+Move+the+pointer+past+the+NULL+character+to+separate+the+name+and+value
++++++++++++++++index%2B%2B;
++++++++++++++++strcpy(headers[index].name,name);++++//+Copy+the+name+to+the+data+structure
++++++++++++++++strcpy(headers[index].value,value);++//+Copy+the+value+to+the+data+structure
++++++++++++}

++++++++}

++++++++if(*line+==+'\r')+//+End+of+headers
++++++++++++break;

++++++++line+=+strtok(NULL,"\n");+//+Get+next+header
++++++++header_count+=+index;
++++}

++++++++++Received+=+GetMailHeader("Received");

}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3437856|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>typedef struct mailHeaders{
 char name[100];
 char value[2000];
}mailHeaders;

int header_count = 0;
mailHeaders headers[30]; // A struct to hold the name value pairs

char *GetMailHeader(char *name)
{
 char *value = NULL;;
 int i;

 for(i=0;i&lt;header_count;i++){
 if(strcmp(name,headers[i].name) == 0){
 value = headers[i].value;
 break;
 }
 }
 return(value);
}


void ReadMail(void)
{

 //Loop through the email message line by line to separate the headers. Then save the name value pairs to a linked list or struct. 
 char *Received = NULL // Received header
 char *mail = NULL; // Buffer that has the email message.
 char *line = NULL; // A line of text in the email. 
 char *name = NULL; // Header name
 char *value = NULL; // Header value

 int index = -1; // Header index


 memset(&amp;headers,'\0',sizeof(mailHeaders));

 line = strtok(mail,"\n");
 while(line != NULL)
 {

 if(*line == '\t') // Tabbed headers
 {
 strcat(headers[index].value,line); // Concatenate the tabbed values
 }
 else
 {
 name = line; 
 value = strchr(line,':'); // Split the name value pairs. 
 if(value != NULL)
 {
 *value='\0'; // NULL the colon 
 value++; // Move the pointer past the NULL character to separate the name and value
 index++;
 strcpy(headers[index].name,name); // Copy the name to the data structure
 strcpy(headers[index].value,value); // Copy the value to the data structure
 }

 }

 if(*line == '\r') // End of headers
 break;

 line = strtok(NULL,"\n"); // Get next header
 header_count = index;
 }

 Received = GetMailHeader("Received");

}
</code></pre>

blocks|key|426278|text|解析这样的报头并不困难，即使是手动逐行解析也是如此。通过查看by\s%2B(\w)%2B\(，正则表达式可能会对此有所帮助。对于C%2B%2B，您可以尝试使用library或that+one。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|426279|entityMap|0|LINK|mutability|MUTABLE|url|http://www.scalingweb.com/mime_parser.php|1|http://www.hotscripts.com/Detailed/76234.html^0|U|C|1Z|7|0|27|8|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]|$9|V|A|W|1|X]]|E|$]]|$1|F|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]|N|$5|I|J|K|E|$L|O]]]]

It is not difficult to parse such headers, even manually line-by-line. A regex could help there by looking at <code>by\s+(\w)+\(</code>. For C++, you could try that <a href="http://www.scalingweb.com/mime_parser.php" rel="nofollow noreferrer">library</a> or <a href="http://www.hotscripts.com/Detailed/76234.html" rel="nofollow noreferrer">that one</a>.

blocks|key|3437769|text|你有没有考虑过使用regular+expressions？|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3437770|Here是内部不可路由地址范围的列表。|3437771|entityMap|0|LINK|mutability|MUTABLE|url|http://www.regular-expressions.info/examples.html|1|http://www.mtmnet.com/PDF_FILES/NonRoutableIPaddresses.PDF^0|9|J|0|0|0|4|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]|N|$5|I|J|K|C|$L|O]]]]

Have you considered using <a href="http://www.regular-expressions.info/examples.html" rel="nofollow noreferrer">regular expressions</a>? 

<a href="http://www.mtmnet.com/PDF_FILES/NonRoutableIPaddresses.PDF" rel="nofollow noreferrer">Here</a> is a list of internal, non-routable address ranges.

We need to parse <code>Received:</code> email headers according to RFC 5321. We need to extract domain\IPs through which the mail has traversed.Also, we need to figure if an IP is an internal IP. Is there already a library which can help out , especially in C\C++. 

For example,

<pre><code>Received: from server.mymailhost.com (mail.mymailhost.com [126.43.75.123])
 by pilot01.cl.msu.edu (8.10.2/8.10.2) with ESMTP id NAA23597;
 Fri, 12 Jul 2002 16:11:20 -0400 (EDT)
</code></pre>

We need to extract the "by" server.

thanks

Parsing email "Received:" headers

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我们需要根据RFC5321解析Received:电子邮件报头。我们需要提取邮件具有traversed.Also的域\ IP，我们需要确定IP是否是内部IP。是否已经有一个库可以提供帮助，特别是在C\C++中。例如,Received: from server.mymailhost.com (mail.mymailhost.com [126.43.75.123])    by pilot01.cl.m

问解析电子邮件"Received:“标头
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