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181
net.c
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181
net.c
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/*
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This file is part of udpxd.
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Copyright (C) 2015 T.v.Dein.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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You can contact me by mail: <tom AT vondein DOT org>.
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*/
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#include "net.h"
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#include "client.h"
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char *ntoa(struct sockaddr_in *src) {
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char *ip;
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ip = inet_ntoa(src->sin_addr);
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return ip;
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}
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/* called each time when the loop restarts to feed select() correctly */
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int fill_set(fd_set *fds) {
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int max = 0;
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client_t *current = NULL;
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client_iter(clients, current) {
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if (current->socket < (int)FD_SETSIZE) {
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if (current->socket > max)
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max = current->socket;
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FD_SET(current->socket, fds);
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}
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else {
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fprintf(stderr, "skipped client, socket too large!\n");
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}
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}
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return max;
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}
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/* return file handle ready to read */
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int get_sender(fd_set *fds) {
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int i = 0;
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while(!FD_ISSET(i, fds))
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i++;
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return i;
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}
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/* bind to a socket, either for listen() or for outgoing src ip binding */
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int bindsocket( char* ip, int port ) {
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int fd;
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struct sockaddr_in addr;
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addr.sin_family = AF_INET;
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addr.sin_addr.s_addr = inet_addr( ip );
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addr.sin_port = htons( port );
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fd = socket( PF_INET, SOCK_DGRAM, IPPROTO_IP );
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if( -1 == bind( fd, (struct sockaddr*)&addr, sizeof( addr ) ) ) {
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fprintf( stderr, "Cannot bind address (%s:%d)\n", ip, port );
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exit( 1 );
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}
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return fd;
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}
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/* handle new or known incoming requests */
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void handle_inside(int inside, char *bindip, struct sockaddr_in *dst) {
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int len;
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unsigned char buffer[MAX_BUFFER_SIZE];
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struct sockaddr_in *src;
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client_t *client;
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int output;
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char *srcip;
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char *dstip = ntoa(dst);
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socklen_t size;
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src = malloc(sizeof(struct sockaddr_in));
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len = recvfrom( inside, buffer, sizeof( buffer ), 0,
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(struct sockaddr*)src, &size );
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srcip = ntoa(src);
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if(VERBOSE) {
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char *srcip = ntoa(src);
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fprintf(stderr, "New incomming request from %s:%d with %d bytes\n",
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srcip, ntohs(src->sin_port), len);
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}
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if(len > 0) {
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/* do we know it ? */
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client = client_find_src(src);
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if(client != NULL) {
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/* yes, we know it, send req out via existing bind socket */
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if(VERBOSE) {
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fprintf(stderr, "Client %s:%d is known, forwarding data to %s:%d\n",
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srcip, ntohs(src->sin_port), dstip, ntohs(dst->sin_port));
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}
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if(sendto(client->socket, buffer, len, 0, (struct sockaddr*)dst, size) < 0) {
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fprintf(stderr, "unable to forward to %s%d", dstip, ntohs(dst->sin_port));
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perror(NULL);
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}
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else {
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client_seen(client);
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}
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}
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else {
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/* unknown client, open new out socket */
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if(VERBOSE) {
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fprintf(stderr, "Client %s:%d is unknown, forwarding data to %s:%d ",
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srcip, ntohs(src->sin_port), dstip, ntohs(dst->sin_port));
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}
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if(bindip == NULL)
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output = bindsocket("0.0.0.0", 0);
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else
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output = bindsocket(bindip, 0);
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/* send req out */
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if(sendto(output, buffer, len, 0, (struct sockaddr*)dst, size) < 0) {
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fprintf(stderr, "unable to forward to %s%d", dstip, ntohs(dst->sin_port));
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perror(NULL);
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}
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else {
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struct sockaddr_in *ret = malloc(size);
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getsockname(output, (struct sockaddr*)ret, (socklen_t *)&size);
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client = client_new(output, src, ret);
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client_add(client);
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if(VERBOSE) {
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if(bindip != NULL) {
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char *bindip = ntoa(ret);
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fprintf(stderr, "from %s:%d\n", bindip, ntohs(ret->sin_port));
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}
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else {
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fprintf(stderr, "\n");
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}
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}
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}
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}
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}
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}
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/* handle answer from the outside */
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void handle_outside(int inside, int outside) {
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int len;
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unsigned char buffer[MAX_BUFFER_SIZE];
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struct sockaddr_in *src;
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client_t *client;
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socklen_t size;
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src = malloc(sizeof(struct sockaddr_in));
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len = recvfrom( outside, buffer, sizeof( buffer ), 0,
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(struct sockaddr*)src, &size );
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if(len > 0) {
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/* do we know it? */
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client = client_find_fd(outside);
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if(client != NULL) {
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/* yes, we know it */
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if(sendto(inside, buffer, len, 0, (struct sockaddr*)client->src, size) < 0) {
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perror("unable to send back to client"); /* FIXME: add src+port */
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client_close(client);
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}
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}
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}
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}
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