8 changed files with 244 additions and 173 deletions
@ -1,56 +1,179 @@ |
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#include "helpers.h" |
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|
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int create_socket(uint16_t port) { |
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int sock; |
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struct sockaddr_in socket_name; |
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void set_timer_and_handler(void (*handler)(int), long int timer_interval) { |
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struct itimerval interval_timer; |
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struct sigaction signal_action; |
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|
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// Installs handler as the signal handler for SIGALRM
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memset(&signal_action, 0, sizeof(signal_action)); |
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signal_action.sa_handler = handler; |
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if (sigaction(SIGALRM, &signal_action, NULL)) { |
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perror("Couldn't install function handler for SIGALRM signals."); |
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exit(EXIT_FAILURE); |
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} |
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|
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// Sets an interval timer to deliver a SIGALRM signal every timer_interval seconds
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interval_timer.it_interval.tv_usec = 0; |
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interval_timer.it_interval.tv_sec = timer_interval; |
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interval_timer.it_value.tv_usec = 0; |
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interval_timer.it_value.tv_sec = timer_interval; |
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|
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if (setitimer(ITIMER_REAL, &interval_timer, NULL) == -1) { |
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perror("Couldn't set timer."); |
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exit(EXIT_FAILURE); |
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} |
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} |
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|
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void enable_echo_broadcast(void) { |
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if (system("echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts") < 0) { |
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perror("Couldn't allow echo broadcasts."); |
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exit(EXIT_FAILURE); |
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} |
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} |
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|
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/*
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* Function based on this snippet: |
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* https://codereview.stackexchange.com/a/58107
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*/ |
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void search_for_neighbors(void) { |
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// Broadcasts ping
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if (system("ping -b 10.255.255.255 -c 3 > /dev/null") < 0) { |
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perror("Couldn't broadcast echo."); |
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exit(EXIT_FAILURE); |
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} |
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|
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// Reads the ARP file checking for connected devices
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FILE *arpCache = fopen(ARP_CACHE, "r"); |
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if (!arpCache) { |
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perror("ARP Cache: Failed to open file \"" ARP_CACHE "\""); |
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exit(EXIT_FAILURE); |
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} |
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|
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// Ignores the first line, which contains the header
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char header[ARP_BUFFER_LEN]; |
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if (!fgets(header, sizeof(header), arpCache)) { |
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perror("Couldn't read ARP file header."); |
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exit(EXIT_FAILURE); |
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} |
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|
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// Extracts IP addresses found in the file
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char ipAddr[ARP_BUFFER_LEN]; |
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int count = 0; |
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while (1 == fscanf(arpCache, ARP_LINE_FORMAT, ipAddr)) { |
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printf("%03d: [%s]\n", ++count, ipAddr); |
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} |
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fclose(arpCache); |
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} |
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|
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/*
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* Function based on this example: |
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* https://www.gnu.org/software/libc/manual/html_node/Inet-Example.html#Inet-Example
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*/ |
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int create_socket_and_listen(uint16_t port, uint8_t backlog_size) { |
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int in_sock; |
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struct sockaddr_in own_name; |
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// Creates the socket
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sock = socket (PF_INET, SOCK_STREAM, 0); //TODO: check if PF_INET is the right one
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if (sock < 0) { |
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in_sock = socket(PF_INET, SOCK_STREAM, 0); |
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if (in_sock < 0) { |
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perror("Couldn't create the socket."); |
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exit(EXIT_FAILURE); |
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} |
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// Gives the socket a name
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socket_name.sin_family = AF_INET; |
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socket_name.sin_port = htons(port); |
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socket_name.sin_addr.s_addr = htonl(INADDR_ANY); |
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own_name.sin_family = AF_INET; |
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own_name.sin_port = htons(port); |
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own_name.sin_addr.s_addr = htonl(INADDR_ANY); |
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// Binds own address structure to socket
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if (bind(sock, (struct sockaddr *) &socket_name, sizeof(socket_name)) < 0) { |
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if (bind(in_sock, (struct sockaddr *) &own_name, sizeof(own_name)) < 0) { |
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perror("Couldn't bind the address structure to the socket."); |
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exit(EXIT_FAILURE); |
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} |
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return sock; |
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if (listen(in_sock, backlog_size) < 0) { |
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perror("Couldn't listen for connections on the socket."); |
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exit(EXIT_FAILURE); |
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} |
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return in_sock; |
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} |
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void send_message(const char *ipv4, uint16_t port, const char *message) { |
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int out_sock; |
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struct sockaddr_in peer_name; |
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// Creates the socket
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out_sock = socket(PF_INET, SOCK_STREAM, 0); |
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if (out_sock < 0) { |
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perror("Couldn't create the socket."); |
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exit(EXIT_FAILURE); |
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} |
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// Connects to the peer
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init_sockaddr(&peer_name, ipv4, port); |
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if (connect(out_sock, (struct sockaddr *) &peer_name, sizeof(peer_name))) { |
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printf("Couldn't connect to the peer.\n"); |
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} else { |
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// Sends data to the peer
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write_to_peer(out_sock, message); |
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} |
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close(out_sock); |
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} |
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void accept_connection(int sock, struct sockaddr_in *peer_name, fd_set *active_fd_set) { |
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size_t peer_name_size = sizeof((*peer_name)); |
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int comm_socket = accept(sock, (struct sockaddr *) peer_name, &peer_name_size); |
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if (comm_socket < 0) { |
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perror("Couldn't accept the connection."); |
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exit(EXIT_FAILURE); |
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} |
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fprintf(stderr, "Connected to host %s, port %hd.\n", |
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inet_ntoa((*peer_name).sin_addr), ntohs((*peer_name).sin_port)); |
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FD_SET(comm_socket, active_fd_set); |
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} |
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void write_to_peer(int file_desc, const char *message) { |
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int num_bytes = write(file_desc, message, strlen(message) + 1); |
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if (num_bytes < 0) { |
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perror("Couldn't write to peer."); |
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exit(EXIT_FAILURE); |
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} |
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} |
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int read_from_client(int file_des, uint16_t max_line) { |
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int read_from_peer(int file_des, uint16_t max_line) { |
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char buffer[max_line]; |
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int nbytes; |
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int num_bytes; |
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nbytes = read(file_des, buffer, sizeof(buffer)); |
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if (nbytes < 0) { |
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perror("Couldn't read from client."); |
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num_bytes = read(file_des, buffer, sizeof(buffer)); |
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if (num_bytes < 0) { |
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perror("Couldn't read from peer."); |
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exit(EXIT_FAILURE); |
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} else if (nbytes == 0) |
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} else if (num_bytes == 0) |
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// End-of-file
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return -1; |
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else { |
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fprintf(stderr, "Server: got message: `%s'\n", buffer); |
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fprintf(stderr, "Got message: `%s'\n", buffer); |
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return 0; |
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} |
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} |
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void init_sockaddr(struct sockaddr_in *name, const char *hostname, uint16_t port) { |
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/*
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* Function based on this example: |
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* https://www.gnu.org/software/libc/manual/html_node/Inet-Example.html#Inet-Example
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*/ |
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void init_sockaddr(struct sockaddr_in *peer_name, const char *ipv4, uint16_t port) { |
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struct hostent *hostinfo; |
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name->sin_family = AF_INET; |
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name->sin_port = htons(port); |
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hostinfo = gethostbyname(hostname); |
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peer_name->sin_family = AF_INET; |
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peer_name->sin_port = htons(port); |
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hostinfo = gethostbyname(ipv4); |
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if (hostinfo == NULL) { |
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fprintf(stderr, "Unknown host %s.\n", hostname); |
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fprintf(stderr, "Unknown host %s.\n", ipv4); |
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exit(EXIT_FAILURE); |
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} |
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name->sin_addr = *(struct in_addr *) hostinfo->h_addr_list[0]; |
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peer_name->sin_addr = *(struct in_addr *) hostinfo->h_addr_list[0]; |
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} |
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|
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