+
+
+/* IP options: log and reject the connection.
+
+Deal with any IP options that are set. On the systems I have looked at,
+the value of MAX_IPOPTLEN has been 40, meaning that there should never be
+more logging data than will fit in big_buffer. Nevertheless, after somebody
+questioned this code, I've added in some paranoid checking.
+
+Given the disuse of options on the internet as of 2024 I'm tempted to
+drop the detailed parsing and logging. */
+
+#ifdef GLIBC_IP_OPTIONS
+# if (!defined __GLIBC__) || (__GLIBC__ < 2)
+# define OPTSTYLE 1
+# else
+# define OPTSTYLE 2
+# endif
+#elif defined DARWIN_IP_OPTIONS
+# define OPTSTYLE 2
+#else
+# define OPTSTYLE 3
+# endif
+
+#if OPTSTYLE == 1
+# define EXIM_IP_OPT_T struct ip_options
+# define OPTSTART (ipopt->__data)
+#elif OPTSTYLE == 2
+# define EXIM_IP_OPT_T struct ip_opts
+# define OPTSTART (ipopt->ip_opts);
+#else
+# define EXIM_IP_OPT_T struct ipoption
+# define OPTSTART (ipopt->ipopt_list);
+#endif
+
+static BOOL
+smtp_in_reject_options(EXIM_IP_OPT_T * ipopt, EXIM_SOCKLEN_T optlen)
+{
+uschar * p, * pend = big_buffer + big_buffer_size;
+uschar * adptr;
+int optcount, sprint_len;
+struct in_addr addr;
+uschar * optstart = US OPTSTART;
+
+DEBUG(D_receive) debug_printf("IP options exist\n");
+
+p = Ustpcpy(big_buffer, "IP options on incoming call:");
+
+for (uschar * opt = optstart; opt && opt < US (ipopt) + optlen; )
+ switch (*opt)
+ {
+ case IPOPT_EOL:
+ opt = NULL;
+ break;
+
+ case IPOPT_NOP:
+ opt++;
+ break;
+
+ case IPOPT_SSRR:
+ case IPOPT_LSRR:
+ if (!
+# if OPTSTYLE == 1
+ string_format(p, pend-p, " %s [@%s%n",
+ *opt == IPOPT_SSRR ? "SSRR" : "LSRR",
+ inet_ntoa(*(struct in_addr *)&ipopt->faddr),
+ &sprint_len)
+# elif OPTSTYLE == 2
+ string_format(p, pend-p, " %s [@%s%n",
+ *opt == IPOPT_SSRR ? "SSRR" : "LSRR",
+ inet_ntoa(ipopt->ip_dst),
+ &sprint_len)
+# else
+ string_format(p, pend-p, " %s [@%s%n",
+ *opt == IPOPT_SSRR ? "SSRR" : "LSRR",
+ inet_ntoa(ipopt->ipopt_dst),
+ &sprint_len)
+# endif
+ )
+ opt = NULL;
+ else
+ {
+ p += sprint_len;
+ optcount = (opt[1] - 3) / sizeof(struct in_addr);
+ adptr = opt + 3;
+ while (optcount-- > 0)
+ {
+ memcpy(&addr, adptr, sizeof(addr));
+ if (!string_format(p, pend - p - 1, "%s%s%n",
+ optcount == 0 ? ":" : "@", inet_ntoa(addr), &sprint_len))
+ { opt = NULL; goto bad_srr; }
+ p += sprint_len;
+ adptr += sizeof(struct in_addr);
+ }
+ *p++ = ']';
+ opt += opt[1];
+ }
+bad_srr: break;
+
+ default:
+ if (pend - p < 4 + 3*opt[1])
+ opt = NULL;
+ else
+ {
+ p = Ustpcpy(p, "[ ");
+ for (int i = 0; i < opt[1]; i++)
+ p += sprintf(CS p, "%2.2x ", opt[i]);
+ *p++ = ']';
+ opt += opt[1];
+ }
+ break;
+ }
+
+*p = '\0';
+log_write(0, LOG_MAIN, "%s", big_buffer);
+
+/* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
+
+log_write(0, LOG_MAIN|LOG_REJECT,
+ "connection from %s refused (IP options)", host_and_ident(FALSE));
+
+smtp_printf("554 SMTP service not available\r\n", SP_NO_MORE);
+return FALSE;
+}
+
+
git://git.exim.org / exim.git / blobdiff