<div dir="ltr"><div class="gmail_default" style="font-size:small;color:rgb(51,51,153)">I am curious: apart from a training prospective at code digging, what was the goal?<br></div><div class="gmail_default" style="font-size:small;color:rgb(51,51,153)">In other words, where did you expect the IP address to come from, if not from a system network socket?<br></div><div class="gmail_default" style="font-size:small;color:rgb(51,51,153)"><br>Have a nice week-end,<br></div><div class="gmail_extra"><div><div class="gmail_signature" data-smartmail="gmail_signature"><font size="1"><span style="color:rgb(102,102,102)">---<br></span><b><span style="color:rgb(102,102,102)">B. R.</span></b><span style="color:rgb(102,102,102)"></span></font></div></div>
<br><div class="gmail_quote">On Sat, Feb 4, 2017 at 12:02 AM, Paul Nickerson <span dir="ltr"><<a href="mailto:pnickerson@cashstar.com" target="_blank">pnickerson@cashstar.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><span class=""><div>> Reading that file, the next likely looking line is:</div><div>> c->addr_text.len = ngx_sock_ntop(c->sockaddr, c->socklen,</div><div>> c->addr_text.data,</div><div>> ls->addr_text_max_len, 0);</div><div><br></div></span><div>Thank you for the boost. From what you said, it looks like the variable is constructed from c->sockaddr</div><div><br></div><div>src/event/ngx_event_accept.c<br></div><div>line 167<br></div><div>c->sockaddr = ngx_palloc(c->pool, socklen);<br></div><div><br></div><div>I chased that down, and it looks like ngx_palloc only allocates some memory; it doesn't fill it. Moving on.</div><div><br></div><div><div>line 173</div><div>ngx_memcpy(c->sockaddr, &sa, socklen);</div></div><div><br></div><div>It looks like ngx_memcpy is a wrapper around the standard C library function memcpy. For memcpy(A, B, C), it copies to destination A from source B, and it does amount C. So now I want to know where &sa comes from.</div><div class="gmail_extra"><br></div><div class="gmail_extra"><div class="gmail_extra">line 70</div><div class="gmail_extra">s = accept(lc->fd, &sa.sockaddr, &socklen);</div><div class="gmail_extra"><br></div><div class="gmail_extra">Here, &sa.sockaddr is being sent into something. I think &sa.sockaddr becomes c->sockaddr, so I chase this.</div><div class="gmail_extra"><br></div><div class="gmail_extra">Bash</div><div class="gmail_extra">man 2 accept<br></div><div class="gmail_extra"><br></div><div class="gmail_extra">accept is a Linux system call: "accept a connection on a socket"</div><div class="gmail_extra">int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);<br></div><div class="gmail_extra"><br></div><div class="gmail_extra">"The argument addr is a pointer to a sockaddr structure. This</div><div class="gmail_extra">structure is filled in with the address of the peer socket, as known</div><div class="gmail_extra">to the communications layer. The exact format of the address</div><div class="gmail_extra">returned addr is determined by the socket's address family (see</div><div class="gmail_extra">socket(2) and the respective protocol man pages). When addr is NULL,</div><div class="gmail_extra">nothing is filled in; in this case, addrlen is not used, and should</div><div class="gmail_extra">also be NULL."</div><div class="gmail_extra"><br></div><div class="gmail_extra">And so, the answer to my question appears to be: $remote_addr is constructed from "struct sockaddr *addr" of the "accept" Linux system call. It is the address of the peer socket.</div><div class="gmail_extra"><br></div><div class="gmail_extra">I am going to read through socket(2) and the respective protocol man pages, but at this point we're outside of NGINX, and so the scope of this mailing list.</div><div class="gmail_extra">Thank you again for your help.</div><span class="HOEnZb"><font color="#888888"><div class="gmail_extra"><br></div><div class="gmail_extra"> ~ Paul Nickerson</div></font></span></div></div><div class="HOEnZb"><div class="h5">
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