1 /*
2 * Copyright (c) 2016-2021, OARC, Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. Neither the name of the copyright holder nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
29 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
31 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32 * POSSIBILITY OF SUCH DAMAGE.
33 */
34
35 #include "config.h"
36
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <unistd.h>
40 #include <string.h>
41 #include <netinet/in.h>
42
43 #include "dnscap_common.h"
44
45 static logerr_t* logerr;
46 static int opt_f = 0;
47 static const char* opt_x = 0;
48
49 output_t template_output;
50
template_usage()51 void template_usage()
52 {
53 fprintf(stderr,
54 "\ntemplate.so options:\n"
55 "\t-? print these instructions and exit\n"
56 "\t-f flag option\n"
57 "\t-x <arg> option with argument\n");
58 }
59
template_getopt(int * argc,char ** argv[])60 void template_getopt(int* argc, char** argv[])
61 {
62 /*
63 * The "getopt" function will be called from the parent to
64 * process plugin options.
65 */
66 int c;
67 while ((c = getopt(*argc, *argv, "?fx:")) != EOF) {
68 switch (c) {
69 case 'f':
70 opt_f = 1;
71 break;
72 case 'x':
73 opt_x = strdup(optarg);
74 break;
75 case '?':
76 template_usage();
77 if (!optopt || optopt == '?') {
78 exit(0);
79 }
80 // fallthrough
81 default:
82 exit(1);
83 }
84 }
85 }
86
template_start(logerr_t * a_logerr)87 int template_start(logerr_t* a_logerr)
88 {
89 /*
90 * The "start" function is called once, when the program
91 * starts. It is used to initialize the plugin. If the
92 * plugin wants to write debugging and or error messages,
93 * it should save the a_logerr pointer passed from the
94 * parent code.
95 */
96 logerr = a_logerr;
97 return 0;
98 }
99
template_stop()100 void template_stop()
101 {
102 /*
103 * The "start" function is called once, when the program
104 * is exiting normally. It might be used to clean up state,
105 * free memory, etc.
106 */
107 }
108
template_open(my_bpftimeval ts)109 int template_open(my_bpftimeval ts)
110 {
111 /*
112 * The "open" function is called at the start of each
113 * collection interval, which might be based on a period
114 * of time or a number of packets. In the original code,
115 * this is where we opened an output pcap file.
116 */
117 return 0;
118 }
119
template_close(my_bpftimeval ts)120 int template_close(my_bpftimeval ts)
121 {
122 /*
123 * The "close" function is called at the end of each
124 * collection interval, which might be based on a period
125 * of time or on a number of packets. In the original code
126 * this is where we closed an output pcap file.
127 */
128 return 0;
129 }
130
template_output(const char * descr,iaddr from,iaddr to,uint8_t proto,unsigned flags,unsigned sport,unsigned dport,my_bpftimeval ts,const u_char * pkt_copy,const unsigned olen,const u_char * payload,const unsigned payloadlen)131 void template_output(const char* descr, iaddr from, iaddr to, uint8_t proto, unsigned flags,
132 unsigned sport, unsigned dport, my_bpftimeval ts,
133 const u_char* pkt_copy, const unsigned olen,
134 const u_char* payload, const unsigned payloadlen)
135 {
136 /*
137 * Here you can "process" a packet. The function is named
138 * "output" because in the original code this is where
139 * packets were outputted.
140 *
141 * if flags & PCAP_OUTPUT_ISDNS != 0 then payload is the start of a DNS message.
142 *
143 * if flags & PCAP_OUTPUT_ISFRAG != 0 then the packet is a fragment.
144 *
145 * if flags & PCAP_OUTPUT_ISLAYER != 0 then the pkt_copy is the same as payload.
146 */
147 }
148