+/*
+ * RFC1122 says the following on data in RST segments:
+ *
+ * 4.2.2.12 RST Segment: RFC-793 Section 3.4
+ *
+ * A TCP SHOULD allow a received RST segment to include data.
+ *
+ * DISCUSSION
+ * It has been suggested that a RST segment could contain
+ * ASCII text that encoded and explained the cause of the
+ * RST. No standard has yet been established for such
+ * data.
+ *
+ */
+
+static void
+print_tcp_rst_data(register const u_char *sp, u_int length)
+{
+ int c;
+
+ if (TTEST2(*sp, length))
+ printf(" [RST");
+ else
+ printf(" [!RST");
+ if (length > MAX_RST_DATA_LEN) {
+ length = MAX_RST_DATA_LEN; /* can use -X for longer */
+ putchar('+'); /* indicate we truncate */
+ }
+ putchar(' ');
+ while (length-- && sp <= snapend) {
+ c = *sp++;
+ safeputchar(c);
+ }
+ putchar(']');
+}
+
+#ifdef HAVE_LIBCRYPTO
+static int
+tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
+ const u_char *data, int length, const u_char *rcvsig)
+{
+ struct tcphdr tp1;
+ u_char sig[TCP_SIGLEN];
+ char zero_proto = 0;
+ MD5_CTX ctx;
+ u_int16_t savecsum, tlen;
+#ifdef INET6
+ struct ip6_hdr *ip6;
+#endif
+ u_int32_t len32;
+ u_int8_t nxt;
+
+ tp1 = *tp;
+
+ if (tcpmd5secret == NULL)
+ return (CANT_CHECK_SIGNATURE);
+
+ MD5_Init(&ctx);
+ /*
+ * Step 1: Update MD5 hash with IP pseudo-header.
+ */
+ if (IP_V(ip) == 4) {
+ MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
+ MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
+ MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
+ MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
+ tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
+ tlen = htons(tlen);
+ MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
+#ifdef INET6
+ } else if (IP_V(ip) == 6) {
+ ip6 = (struct ip6_hdr *)ip;
+ MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
+ MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
+ len32 = htonl(ntohs(ip6->ip6_plen));
+ MD5_Update(&ctx, (char *)&len32, sizeof(len32));
+ nxt = 0;
+ MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
+ MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
+ MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
+ nxt = IPPROTO_TCP;
+ MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
+#endif
+ } else
+ return (CANT_CHECK_SIGNATURE);
+
+ /*
+ * Step 2: Update MD5 hash with TCP header, excluding options.
+ * The TCP checksum must be set to zero.
+ */
+ savecsum = tp1.th_sum;
+ tp1.th_sum = 0;
+ MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
+ tp1.th_sum = savecsum;
+ /*
+ * Step 3: Update MD5 hash with TCP segment data, if present.
+ */
+ if (length > 0)
+ MD5_Update(&ctx, data, length);
+ /*
+ * Step 4: Update MD5 hash with shared secret.
+ */
+ MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
+ MD5_Final(sig, &ctx);
+
+ if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
+ return (SIGNATURE_VALID);
+ else
+ return (SIGNATURE_INVALID);
+}
+#endif /* HAVE_LIBCRYPTO */
projects / tcpdump / blobdiff