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- /*
- meta.c -- handle the meta communication
- Copyright (C) 2000-2017 Guus Sliepen <guus@tinc-vpn.org>,
- 2000-2005 Ivo Timmermans
- 2006 Scott Lamb <slamb@slamb.org>
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
- #include "system.h"
- #include <openssl/err.h>
- #include <openssl/evp.h>
- #include "avl_tree.h"
- #include "connection.h"
- #include "logger.h"
- #include "meta.h"
- #include "net.h"
- #include "protocol.h"
- #include "proxy.h"
- #include "utils.h"
- #include "xalloc.h"
- bool send_meta(connection_t *c, const char *buffer, int length) {
- int outlen;
- int result;
- ifdebug(META) logger(LOG_DEBUG, "Sending %d bytes of metadata to %s (%s)", length,
- c->name, c->hostname);
- if(!c->outbuflen) {
- c->last_flushed_time = now;
- }
- /* Find room in connection's buffer */
- if(length + c->outbuflen > c->outbufsize) {
- c->outbufsize = length + c->outbuflen;
- c->outbuf = xrealloc(c->outbuf, c->outbufsize);
- }
- if(length + c->outbuflen + c->outbufstart > c->outbufsize) {
- memmove(c->outbuf, c->outbuf + c->outbufstart, c->outbuflen);
- c->outbufstart = 0;
- }
- /* Add our data to buffer */
- if(c->status.encryptout) {
- /* Check encryption limits */
- if((uint64_t)length > c->outbudget) {
- ifdebug(META) logger(LOG_ERR, "Byte limit exceeded for encryption to %s (%s)", c->name, c->hostname);
- return false;
- } else {
- c->outbudget -= length;
- }
- result = EVP_EncryptUpdate(c->outctx, (unsigned char *)c->outbuf + c->outbufstart + c->outbuflen,
- &outlen, (unsigned char *)buffer, length);
- if(!result || outlen < length) {
- logger(LOG_ERR, "Error while encrypting metadata to %s (%s): %s",
- c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
- return false;
- } else if(outlen > length) {
- logger(LOG_EMERG, "Encrypted data too long! Heap corrupted!");
- abort();
- }
- c->outbuflen += outlen;
- } else {
- memcpy(c->outbuf + c->outbufstart + c->outbuflen, buffer, length);
- c->outbuflen += length;
- }
- return true;
- }
- bool flush_meta(connection_t *c) {
- int result;
- ifdebug(META) logger(LOG_DEBUG, "Flushing %d bytes to %s (%s)",
- c->outbuflen, c->name, c->hostname);
- while(c->outbuflen) {
- result = send(c->socket, c->outbuf + c->outbufstart, c->outbuflen, 0);
- if(result <= 0) {
- if(!errno || errno == EPIPE) {
- ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection closed by %s (%s)",
- c->name, c->hostname);
- } else if(errno == EINTR) {
- continue;
- } else if(sockwouldblock(sockerrno)) {
- ifdebug(META) logger(LOG_DEBUG, "Flushing %d bytes to %s (%s) would block",
- c->outbuflen, c->name, c->hostname);
- return true;
- } else {
- logger(LOG_ERR, "Flushing meta data to %s (%s) failed: %s", c->name,
- c->hostname, sockstrerror(sockerrno));
- }
- return false;
- }
- c->outbufstart += result;
- c->outbuflen -= result;
- }
- c->outbufstart = 0; /* avoid unnecessary memmoves */
- return true;
- }
- void broadcast_meta(connection_t *from, const char *buffer, int length) {
- avl_node_t *node;
- connection_t *c;
- for(node = connection_tree->head; node; node = node->next) {
- c = node->data;
- if(c != from && c->status.active) {
- send_meta(c, buffer, length);
- }
- }
- }
- bool receive_meta(connection_t *c) {
- int oldlen, i, result;
- int lenin, lenout, reqlen;
- bool decrypted = false;
- char inbuf[MAXBUFSIZE];
- /* Strategy:
- - Read as much as possible from the TCP socket in one go.
- - Decrypt it.
- - Check if a full request is in the input buffer.
- - If yes, process request and remove it from the buffer,
- then check again.
- - If not, keep stuff in buffer and exit.
- */
- lenin = recv(c->socket, c->buffer + c->buflen, MAXBUFSIZE - c->buflen, 0);
- if(lenin <= 0) {
- if(!lenin || !errno) {
- ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection closed by %s (%s)",
- c->name, c->hostname);
- } else if(sockwouldblock(sockerrno)) {
- return true;
- } else
- logger(LOG_ERR, "Metadata socket read error for %s (%s): %s",
- c->name, c->hostname, sockstrerror(sockerrno));
- return false;
- }
- oldlen = c->buflen;
- c->buflen += lenin;
- while(lenin > 0) {
- reqlen = 0;
- /* Is it proxy metadata? */
- if(c->allow_request == PROXY) {
- reqlen = receive_proxy_meta(c);
- if(reqlen < 0) {
- return false;
- }
- goto consume;
- }
- /* Decrypt */
- if(c->status.decryptin && !decrypted) {
- /* Check decryption limits */
- if((uint64_t)lenin > c->inbudget) {
- ifdebug(META) logger(LOG_ERR, "Byte limit exceeded for decryption from %s (%s)", c->name, c->hostname);
- return false;
- } else {
- c->inbudget -= lenin;
- }
- result = EVP_DecryptUpdate(c->inctx, (unsigned char *)inbuf, &lenout, (unsigned char *)c->buffer + oldlen, lenin);
- if(!result || lenout != lenin) {
- logger(LOG_ERR, "Error while decrypting metadata from %s (%s): %s",
- c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
- return false;
- }
- memcpy(c->buffer + oldlen, inbuf, lenin);
- decrypted = true;
- }
- /* Are we receiving a TCPpacket? */
- if(c->tcplen) {
- if(c->tcplen <= c->buflen) {
- if(c->allow_request != ALL) {
- logger(LOG_ERR, "Got unauthorized TCP packet from %s (%s)", c->name, c->hostname);
- return false;
- }
- receive_tcppacket(c, c->buffer, c->tcplen);
- reqlen = c->tcplen;
- c->tcplen = 0;
- }
- } else {
- /* Otherwise we are waiting for a request */
- for(i = oldlen; i < c->buflen; i++) {
- if(c->buffer[i] == '\n') {
- c->buffer[i] = '\0'; /* replace end-of-line by end-of-string so we can use sscanf */
- c->reqlen = reqlen = i + 1;
- break;
- }
- }
- if(reqlen && !receive_request(c)) {
- return false;
- }
- }
- consume:
- if(reqlen) {
- c->buflen -= reqlen;
- lenin -= reqlen - oldlen;
- memmove(c->buffer, c->buffer + reqlen, c->buflen);
- oldlen = 0;
- continue;
- } else {
- break;
- }
- }
- if(c->buflen >= MAXBUFSIZE) {
- logger(LOG_ERR, "Metadata read buffer overflow for %s (%s)",
- c->name, c->hostname);
- return false;
- }
- return true;
- }
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