301 lines
6.8 KiB
C
301 lines
6.8 KiB
C
/*
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* network.c - Netowrking interface to and from postfix
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* The author licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#include <stdint.h>
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#include <stddef.h>
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#include <sys/types.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdbool.h>
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#include <sysexits.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <netdb.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <poll.h>
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#include <pthread.h>
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#include "version.h"
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#include "config.h"
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#include "attach.h"
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#include "detect.h"
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#include "network.h"
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int parentfd = 0;
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/* Used to ingest data from a client */
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void receive_mail(struct mail_recv_t* rec){
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if(!rec->in_body){
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/* As long as we are outside the real mail body
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* we can basically passthrough the commands
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*/
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rec->in_len += rec->n;
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rec->input_buffer = realloc(rec->input_buffer, rec->in_len);
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strncat(rec->input_buffer,rec->buf, rec->n);
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rec->body_p = detect_start_of_body(rec->input_buffer);
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if(rec->body_p != NULL){
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/* We reached the beginning of the body
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* now! */
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rec->body_offs = rec->body_p - rec->input_buffer;
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rec->in_body = true;
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write((rec->fds[1].fd),
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rec->input_buffer+(rec->in_len-rec->n),
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rec->body_offs-(rec->in_len-rec->n));
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printf("Beginning of message found! Awaiting end...\n");
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}else{
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write((rec->fds[1].fd), rec->buf, rec->n);
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}
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} else if(!rec->after_body){
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/* We keep the body until we have it completely
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*/
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rec->in_len += rec->n;
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rec->input_buffer = realloc(rec->input_buffer, rec->in_len);
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strncat(rec->input_buffer, rec->buf, rec->n);
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rec->body_p = detect_end_of_body(rec->input_buffer+
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rec->body_offs);
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if(rec->body_p != NULL){
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printf("Data found, interpreting...\n");
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size_t body_len = rec->body_p-
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(rec->input_buffer+rec->body_offs);
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/* Copy the after body message and reduce original
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* pointer to mail size to allow reallocs */
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size_t abody_len = rec->in_len-
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(rec->body_offs+body_len);
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void * abody = malloc(abody_len);
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memcpy(abody,
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rec->input_buffer+rec->body_offs+body_len,
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abody_len);
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/* reduce the input buffer to the body */
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memmove(rec->input_buffer,
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rec->input_buffer+rec->body_offs, body_len);
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rec->input_buffer = realloc(rec->input_buffer,
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body_len + 1);
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rec->input_buffer[body_len] = 0;
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rec->in_len = body_len;
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char* new_body = attach_files(
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rec->input_buffer,
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rec->in_len);
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if(new_body != NULL){
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/* Write the replacement */
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write((rec->fds[1].fd), new_body,
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strlen(new_body));
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free(new_body);
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rec->input_buffer = NULL;
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rec->in_len = 0;
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}else{
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/* Write the original */
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write((rec->fds[1].fd),
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rec->input_buffer+rec->body_offs,
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body_len);
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}
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/* Rest of conversation after mail itself. Most likely
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* just a CRLF.CRLF abd QUIT */
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write((rec->fds[1].fd),
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abody,
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abody_len);
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free(abody);
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rec->after_body = true;
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}
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}else{
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write((rec->fds[1].fd), rec->buf, rec->n);
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}
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return;
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}
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/* Handle an incoming client connection. Passes every command through to the
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* server on the other end, apart from the E-Mail message itself, identified by
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* the DATA command. If the data command fails, then we just error out by
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* disconnecting both sides of this tunnel.
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*/
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void* client_handle_async(void* params){
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struct client_info * cli = params;
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struct sockaddr_in serveraddr; /* server's addr */
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int remote_fd;
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remote_fd = socket(AF_INET, SOCK_STREAM, 0);
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if (remote_fd < 0){
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perror("error opening client socket");
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close(cli->fd);
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free(cli);
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return NULL;
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}
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/* build the server's Internet address */
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bzero((char *) &serveraddr, sizeof(serveraddr));
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serveraddr.sin_family = AF_INET;
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serveraddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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serveraddr.sin_port = htons(forward_port);
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struct mail_recv_t rec;
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memset(&rec,0,sizeof(rec));
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/* connect: create a connection with the server */
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if (connect(remote_fd,(struct sockaddr *) &serveraddr,
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sizeof(serveraddr)) < 0){
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perror("ERROR connecting client socket");
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goto closeup;
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}
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rec.fds[0].fd = cli->fd;
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rec.fds[0].events = POLLIN;
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rec.fds[1].fd = remote_fd;
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rec.fds[1].events = POLLIN;
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int timeout = (10 * 1000); /* 10 seconds */
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rec.input_buffer = malloc(1);
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rec.input_buffer[0]=0;
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rec.in_len = 1;
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rec.in_body = false;
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rec.after_body = false;
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rec.body_p = NULL;
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rec.body_offs = 0;
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while(poll(rec.fds, 2, timeout) > 0){
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for(size_t i = 0; i < 2; i++){
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if(!(rec.fds[i].revents & POLLIN)){
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continue;
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}
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bzero(rec.buf, sizeof(rec.buf));
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rec.n = read(rec.fds[i].fd, rec.buf, sizeof(rec.buf)-1);
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if (rec.n <= 0) {
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goto closeup;
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}
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if(i == 0){
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receive_mail(&rec);
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}else{
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write((rec.fds[!i].fd), rec.buf, rec.n);
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}
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}
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}
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closeup:
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printf("Disconnecting...\n");
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close(cli->fd);
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close(remote_fd);
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free(cli);
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free(rec.input_buffer);
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return NULL;
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}
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int init_net(){
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struct sockaddr_in serveraddr;
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int optval;
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parentfd = socket(AF_INET, SOCK_STREAM, 0);
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if (parentfd < 0){
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perror("ERROR opening socket");
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return -1;
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}
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optval = 1;
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setsockopt(parentfd, SOL_SOCKET, SO_REUSEADDR,
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(const void *)&optval , sizeof(int));
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bzero((char *) &serveraddr, sizeof(serveraddr));
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serveraddr.sin_family = AF_INET;
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serveraddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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serveraddr.sin_port = htons((unsigned short)listen_port);
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if (bind(parentfd, (struct sockaddr *) &serveraddr,
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sizeof(serveraddr)) < 0) {
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perror("ERROR on binding");
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return -1;
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}
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return 0;
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}
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void loop_clients(){
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/*
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* listen: make this socket ready to accept connection requests
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*/
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if (listen(parentfd, 5) < 0){
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perror("Failed to listen on socket...");
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}
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int childfd;
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struct sockaddr_in clientaddr;
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socklen_t clientlen = sizeof(clientaddr);
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printf("Listening for clients on port %u\n", listen_port);
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while (1) {
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childfd = accept(parentfd, (struct sockaddr *) &clientaddr, &clientlen);
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if (childfd < 0){
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perror("accept failed");
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}
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struct client_info* cli = malloc(sizeof(struct client_info));
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memset(cli, 0, sizeof(struct client_info));
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cli->fd = childfd;
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pthread_t executing_thread;
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int status = pthread_create(&executing_thread, NULL,
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client_handle_async, cli);
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if(status < 0){
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fprintf(stderr, "Failed to create thread: %s\n",
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strerror(status));
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}
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}
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return;
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}
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