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- /*
- Copyright (c) 2014, Nils Schneider <nils@nilsschneider.net>
- 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.
- 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 <stdio.h>
- #include <unistd.h>
- #include <stdlib.h>
- #include <sys/types.h>
- #include <sys/socket.h>
- #include <net/if.h>
- #include <netinet/in.h>
- #include <arpa/inet.h>
- #include <string.h>
- void usage() {
- puts("Usage: gluon-announced [-h] -g <group> -p <port> -i <if0> [-i <if1> ..] -s <script>");
- puts(" -g <ip6> multicast group, e.g. ff02:0:0:0:0:0:2:1001");
- puts(" -p <int> port number to listen on");
- puts(" -i <string> interface on which the group is joined");
- puts(" -s <string> script to be executed for each request");
- puts(" -h this help\n");
- }
- /* The maximum size of output returned is limited to 8192 bytes (including
- * terminating null byte) for now. If this turns out to be problem, a
- * dynamic buffer should be implemented instead of increasing the
- * limit.
- */
- #define BUFFER 8192
- char *run_script(size_t *length, const char *script) {
- FILE *f;
- char *buffer;
- buffer = calloc(BUFFER, sizeof(char));
- if (buffer == NULL) {
- fprintf(stderr, "couldn't allocate buffer\n");
- return NULL;
- }
- f = popen(script, "r");
- size_t read_bytes = 0;
- while (1) {
- ssize_t ret = fread(buffer+read_bytes, sizeof(char), BUFFER-read_bytes, f);
- if (ret <= 0)
- break;
- read_bytes += ret;
- }
- int ret = pclose(f);
- if (ret != 0)
- fprintf(stderr, "script exited with status %d\n", ret);
- *length = read_bytes;
- return buffer;
- }
- void join_mcast(const int sock, const struct in6_addr addr, const char *iface) {
- struct ipv6_mreq mreq;
- mreq.ipv6mr_multiaddr = addr;
- mreq.ipv6mr_interface = if_nametoindex(iface);
- if (mreq.ipv6mr_interface == 0)
- goto error;
- if (setsockopt(sock, IPPROTO_IPV6, IPV6_JOIN_GROUP, &mreq, sizeof(mreq)) == -1)
- goto error;
- return;
- error:
- fprintf(stderr, "Could not join multicast group on %s: ", iface);
- perror(NULL);
- return;
- }
- #define REQUESTSIZE 64
- char *recvrequest(const int sock, struct sockaddr *client_addr, socklen_t *clilen) {
- char request_buffer[REQUESTSIZE];
- ssize_t read_bytes;
- read_bytes = recvfrom(sock, request_buffer, sizeof(request_buffer), 0, client_addr, clilen);
- if (read_bytes < 0) {
- perror("recvfrom failed");
- exit(EXIT_FAILURE);
- }
- char *request = strndup(request_buffer, read_bytes);
- if (request == NULL)
- perror("Could not receive request");
- return strsep(&request, "\r\n\t ");
- }
- void serve(const int sock, const char *script) {
- char *request;
- socklen_t clilen;
- struct sockaddr_in6 client_addr;
- clilen = sizeof(client_addr);
- while (1) {
- request = recvrequest(sock, (struct sockaddr*)&client_addr, &clilen);
- int cmp = strcmp(request, "nodeinfo");
- free(request);
- if (cmp != 0)
- continue;
- char *msg;
- size_t msg_length;
- msg = run_script(&msg_length, script);
- if (sendto(sock, msg, msg_length, 0, (struct sockaddr *)&client_addr, sizeof(client_addr)) < 0) {
- perror("sendto failed");
- exit(EXIT_FAILURE);
- }
- free(msg);
- }
- }
- int main(int argc, char **argv) {
- int sock;
- struct sockaddr_in6 server_addr = {};
- char *script = NULL;
- struct in6_addr mgroup_addr;
- sock = socket(PF_INET6, SOCK_DGRAM, 0);
- if (sock < 0) {
- perror("creating socket");
- exit(EXIT_FAILURE);
- }
- server_addr.sin6_family = AF_INET6;
- server_addr.sin6_addr = in6addr_any;
- opterr = 0;
- int group_set = 0;
- int c;
- while ((c = getopt(argc, argv, "p:g:s:i:h")) != -1)
- switch (c) {
- case 'p':
- server_addr.sin6_port = htons(atoi(optarg));
- break;
- case 'g':
- if (!inet_pton(AF_INET6, optarg, &mgroup_addr)) {
- perror("Invalid multicast group. This message will probably confuse you");
- exit(EXIT_FAILURE);
- }
- group_set = 1;
- break;
- case 's':
- script = optarg;
- break;
- case 'i':
- if (!group_set) {
- fprintf(stderr, "Multicast group must be given before interface.\n");
- exit(EXIT_FAILURE);
- }
- join_mcast(sock, mgroup_addr, optarg);
- break;
- case 'h':
- usage();
- exit(EXIT_SUCCESS);
- break;
- default:
- fprintf(stderr, "Invalid parameter %c ignored.\n", c);
- }
- if (script == NULL) {
- fprintf(stderr, "No script given\n");
- exit(EXIT_FAILURE);
- }
- if (bind(sock, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
- perror("bind failed");
- exit(EXIT_FAILURE);
- }
- serve(sock, script);
- return EXIT_FAILURE;
- }
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