Adding upstream version 2.3.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>

plugins/asudp/asudp.c

@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 2025 OARC, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/udp.h>
+#include <sys/socket.h>
+
+#include "dnscap_common.h"
+
+enum plugin_type asudp_type()
+{
+    return plugin_filter;
+}
+
+void asudp_usage()
+{
+    fprintf(stderr,
+        "\nasudp.so options:\n"
+        "\t-T         skip packets that would be truncated\n"
+        "\t-?         print these instructions and exit\n");
+}
+
+static int skip_truncated = 0;
+
+void asudp_getopt(int* argc, char** argv[])
+{
+    int c;
+    while ((c = getopt(*argc, *argv, "T?")) != EOF) {
+        switch (c) {
+        case 'T':
+            skip_truncated = 1;
+            break;
+        case '?':
+            asudp_usage();
+            if (!optopt || optopt == '?') {
+                exit(0);
+            }
+            // fallthrough
+        default:
+            exit(1);
+        }
+    }
+}
+
+static set_output_pkt_t asudp_set_output_pkt = 0;
+
+void asudp_extension(int ext, void* arg)
+{
+    switch (ext) {
+    case DNSCAP_EXT_SET_OUTPUT_PKT:
+        asudp_set_output_pkt = (set_output_pkt_t)arg;
+        break;
+    }
+}
+
+struct _pkt {
+    union {
+        struct ip      iphdr;
+        struct ip6_hdr ip6_hdr;
+    };
+    struct udphdr updhdr;
+    uint8_t       payload[0xffff];
+};
+static uint8_t _pkt[sizeof(struct _pkt)];
+
+int asudp_filter(const char* descr, iaddr* from, iaddr* to, uint8_t proto, unsigned flags,
+    unsigned sport, unsigned dport, my_bpftimeval ts,
+    u_char* pkt_copy, const unsigned olen,
+    u_char* payload, const unsigned payloadlen)
+{
+    if (!asudp_set_output_pkt)
+        return 0;
+    if (!(flags & DNSCAP_OUTPUT_ISDNS) || !payloadlen) {
+        return 1;
+    }
+
+    size_t   plen = payloadlen;
+    uint8_t* pkt  = _pkt;
+
+    switch (from->af) {
+    case AF_INET: {
+        if (plen > sizeof(((struct _pkt*)0)->payload) - sizeof(struct ip) - sizeof(struct udphdr)) {
+            if (skip_truncated)
+                return 1;
+            plen = sizeof(((struct _pkt*)0)->payload) - sizeof(struct ip) - sizeof(struct udphdr);
+        }
+
+        struct ip ip = {};
+        ip.ip_hl     = 5;
+        ip.ip_v      = 4;
+        ip.ip_len    = htons(sizeof(struct ip) + sizeof(struct udphdr) + plen);
+        ip.ip_ttl    = 255;
+        ip.ip_p      = IPPROTO_UDP;
+        ip.ip_src    = from->u.a4;
+        ip.ip_dst    = to->u.a4;
+        memcpy(pkt, &ip, sizeof(struct ip));
+        pkt += sizeof(struct ip);
+        break;
+    }
+    case AF_INET6: {
+        if (plen > sizeof(((struct _pkt*)0)->payload) - sizeof(struct ip6_hdr) - sizeof(struct udphdr)) {
+            if (skip_truncated)
+                return 1;
+            plen = sizeof(((struct _pkt*)0)->payload) - sizeof(struct ip6_hdr) - sizeof(struct udphdr);
+        }
+
+        struct ip6_hdr ip6 = {};
+        ip6.ip6_vfc        = 0x60;
+        ip6.ip6_plen       = htons(sizeof(struct udphdr) + plen);
+        ip6.ip6_nxt        = IPPROTO_UDP;
+        ip6.ip6_src        = from->u.a6;
+        ip6.ip6_dst        = to->u.a6;
+        memcpy(pkt, &ip6, sizeof(struct ip6_hdr));
+        pkt += sizeof(struct ip6_hdr);
+        break;
+    }
+    default:
+        return 1;
+    }
+
+    struct udphdr udp = {};
+    udp.uh_sport      = htons(sport);
+    udp.uh_dport      = htons(dport);
+    udp.uh_ulen       = htons(sizeof(struct udphdr) + plen);
+    memcpy(pkt, &udp, sizeof(struct udphdr));
+    pkt += sizeof(struct udphdr);
+
+    memcpy(pkt, payload, plen);
+    pkt += plen;
+
+    asudp_set_output_pkt(_pkt, pkt - _pkt);
+
+    return 0;
+}