332 lines
7.6 KiB
C
332 lines
7.6 KiB
C
/*
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* Mailattach - a program to remove attachments and replace them with links.
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* Licensed under the Apache 2.0 License. Parts taken from the sendmail
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* libmilter sample. License restrictions from their license may apply.
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*/
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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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/*
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* error - wrapper for perror
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*/
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void error(char *msg) {
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perror(msg);
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exit(1);
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}
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struct mail_recv_t{
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char* input_buffer;
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size_t in_len;
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bool in_body;
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bool after_body;
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char* body_p;
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size_t body_offs;
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struct pollfd fds[2];
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int n;
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char buf[1000];
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};
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struct client_info {
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int fd;
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};
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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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}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 message */
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write((rec->fds[1].fd),
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abody,
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abody_len);
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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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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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error("ERROR opening client socket");
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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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/* 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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error("ERROR connecting");
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}
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struct mail_recv_t rec;
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memset(&rec,0,sizeof(rec));
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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 clients\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 main(int argc, char* argv[]){
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printf("INIT\n");
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printf("Arguments passed on:\n");
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for(int i = 0; i < argc; i++){
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printf("\t%i:%s\n",i, argv[i]);
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}
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int parentfd; /* parent socket */
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int childfd; /* child socket */
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socklen_t clientlen; /* byte size of client's address */
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struct sockaddr_in serveraddr; /* server's addr */
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struct sockaddr_in clientaddr; /* client addr */
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struct hostent *hostp; /* client host info */
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char *hostaddrp; /* dotted decimal host addr string */
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int optval; /* flag value for setsockopt */
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/*
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* socket: create the parent socket
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*/
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parentfd = socket(AF_INET, SOCK_STREAM, 0);
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if (parentfd < 0){
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error("ERROR opening socket");
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}
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/* setsockopt: Handy debugging trick that lets
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* us rerun the server immediately after we kill it;
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* otherwise we have to wait about 20 secs.
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* Eliminates "ERROR on binding: Address already in use" error.
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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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/*
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* build the server's Internet address
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*/
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bzero((char *) &serveraddr, sizeof(serveraddr));
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/* this is an Internet address */
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serveraddr.sin_family = AF_INET;
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/* let the system figure out our IP address */
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serveraddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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/* this is the port we will listen on */
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serveraddr.sin_port = htons((unsigned short)listen_port);
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/*
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* bind: associate the parent socket with a port
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*/
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if (bind(parentfd, (struct sockaddr *) &serveraddr,
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sizeof(serveraddr)) < 0) {
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error("ERROR on binding");
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}
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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) /* allow 5 requests to queue up */
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error("ERROR on listen");
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/*
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* main loop: wait for a connection request, echo input line,
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* then close connection.
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*/
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clientlen = sizeof(clientaddr);
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char hostaddr_str[20];
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inet_ntop(AF_INET,(struct sockaddr *) &serveraddr, hostaddr_str, 20);
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printf("Listening for clients on port %u\n", listen_port);
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while (1) {
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/*
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* accept: wait for a connection request
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*/
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childfd = accept(parentfd, (struct sockaddr *) &clientaddr, &clientlen);
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if (childfd < 0)
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error("ERROR on accept");
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/*
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* gethostbyaddr: determine who sent the message
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*/
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hostp = gethostbyaddr((const char *)&clientaddr.sin_addr.s_addr,
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sizeof(clientaddr.sin_addr.s_addr), AF_INET);
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if (hostp == NULL)
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error("ERROR on gethostbyaddr");
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hostaddrp = inet_ntoa(clientaddr.sin_addr);
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if (hostaddrp == NULL)
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error("ERROR on inet_ntoa\n");
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printf("server established connection with %s (%s) fd %i\n",
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hostp->h_name, hostaddrp, childfd);
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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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error("Failed to create thread");
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}
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}
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return EX_TEMPFAIL;
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}
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