/********************************************************************************
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* Copyright: (C) 2022 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: socket.c
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* Description: This file is for socket API functions
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*
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* Version: 1.0.0(18/04/22)
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* Author: Guo Wenxue <guowenxue@gmail.com>
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* ChangeLog: 1, Release initial version on "18/04/22 17:09:59"
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*
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********************************************************************************/
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <netdb.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/un.h>
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#include <poll.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <linux/sockios.h>
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netinet/tcp.h>
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#include <arpa/inet.h>
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#include <sys/resource.h>
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#include "socket.h"
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#include "logger.h"
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/* description: initial socket context
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* input args:
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* $sock: socket context pointer
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* $host: connect server hostname for client mode, unused for server mode
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* $port: connect server port for client mode or listen port for server mode
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* return value: <0: failure 0:ok
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*/
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int socket_init(socket_ctx_t *sock, char *host, int port)
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{
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if( !sock || port<=0 )
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return -1;
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memset( sock, 0, sizeof(*sock) );
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sock->fd = -1;
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sock->port = port;
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if( host ) /* server no need it */
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{
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strncpy(sock->host, host, HOSTNAME_LEN);
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}
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return 0;
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}
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/* description: close socket
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* input args:
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* $sock: socket context pointer
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* return value: <0: failure 0:ok
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*/
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int socket_term(socket_ctx_t *sock)
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{
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if( !sock )
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return -1;
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if( sock->fd > 0)
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{
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close(sock->fd);
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sock->fd = -1;
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sock->connected = 0;
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}
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return 0;
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}
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/* description: socket server start listen
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* input args:
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* $sock: socket context pointer
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* return value: <0: failure 0:ok
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*/
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#if 0 /* --TBD-- */
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int socket_listen(socket_ctx_t *sock)
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{
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int rv = 0;
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struct sockaddr_in addr;
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int backlog = 13;
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if( !sock )
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return -1;
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set_socket_rlimit(); /* set max open socket count */
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}
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#endif
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/* description: check socket connect status
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* input args:
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* $sock: socket context pointer
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* return value: 1: connected 0:disconnected
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*/
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int socket_connected(socket_ctx_t *sock)
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{
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struct tcp_info info;
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int len=sizeof(info);
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int changed = 0;
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if( !sock )
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{
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return 0;
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}
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if( sock->fd < 0 )
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{
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/* socket is connected before but got disconnected now */
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changed = sock->connected ? 1 : 0;
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sock->connected = 0;
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goto out;
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}
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getsockopt(sock->fd, IPPROTO_TCP, TCP_INFO, &info, (socklen_t *)&len);
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if( TCP_ESTABLISHED==info.tcpi_state )
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{
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/* socket is disconnected before but got connected now */
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changed = !sock->connected ? 1 : 0;
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sock->connected = 1;
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}
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else
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{
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/* socket is connected before but got disconnected now */
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changed = sock->connected ? 1 : 0;
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sock->connected = 0;
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}
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out:
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if( changed )
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{
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log_info("socket status got %s\n", sock->connected?"connected":"disconnected");
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}
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return sock->connected;
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}
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/* description: socket connect to server in block mode
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* input args:
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* $sock: socket context pointer
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* return value: <0: failure 0:ok
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*/
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int socket_connect(socket_ctx_t *sock)
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{
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int rv = 0;
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int sockfd = 0;
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char service[20];
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struct addrinfo hints, *rp;
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struct addrinfo *res = NULL;
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struct in_addr inaddr;
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struct sockaddr_in addr;
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int len = sizeof(addr);
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if( !sock )
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return -1;
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socket_term(sock);
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/*+--------------------------------------------------+
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*| use getaddrinfo() to do domain name translation |
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*+--------------------------------------------------+*/
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memset(&hints, 0, sizeof(struct addrinfo));
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hints.ai_family = AF_INET; /* Only support IPv4 */
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_protocol = IPPROTO_TCP; /* TCP protocol */
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/* If $host is a valid IP address, then don't use name resolution */
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if( inet_aton(sock->host, &inaddr) )
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{
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//log_info("%s is a valid IP address, don't use domain name resolution.\n", sock->host);
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hints.ai_flags |= AI_NUMERICHOST;
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}
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/* Obtain address(es) matching host/port */
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snprintf(service, sizeof(service), "%d", sock->port);
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if( (rv=getaddrinfo(sock->host, service, &hints, &res)) )
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{
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log_error("getaddrinfo() parser [%s:%s] failed: %s\n", sock->host, service, gai_strerror(rv));
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return -3;
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}
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/* getaddrinfo() returns a list of address structures. Try each
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address until we successfully connect or bind */
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for (rp=res; rp!=NULL; rp=rp->ai_next)
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{
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#if 0
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char ipaddr[INET_ADDRSTRLEN];
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struct sockaddr_in *sp = (struct sockaddr_in *) rp->ai_addr;
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/* print domain name translation result */
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memset( ipaddr, 0, sizeof(ipaddr) );
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if( inet_ntop(AF_INET, &sp->sin_addr, ipaddr, sizeof(ipaddr)) )
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{
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log_info("domain name resolution [%s->%s]\n", sock->host, ipaddr);
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}
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#endif
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/* Create the socket */
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sockfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
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if( sockfd < 0)
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{
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log_error("socket() create failed: %s\n", strerror(errno));
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rv = -3;
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continue;
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}
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/* connect to server */
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rv = connect(sockfd, rp->ai_addr, len);
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if( 0 == rv )
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{
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sock->fd = sockfd;
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log_info("Connect to server[%s:%d] on fd[%d] successfully!\n", sock->host, sock->port, sockfd);
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break;
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}
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else
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{
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/* socket connect get error, try another IP address */
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close(sockfd);
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continue;
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}
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}
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freeaddrinfo(res);
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return rv;
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}
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/* description: send data from the socket
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* input args:
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* $sock : socket context pointer
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* $data : socket send data
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* $bytes: socket send data bytes
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* return value: <0: failure 0:ok
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*/
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int socket_send(socket_ctx_t *sock, char *data, int bytes)
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{
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int rv = 0;
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int i = 0;
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int left_bytes = bytes;
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if( !sock || !data || bytes<= 0 )
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return -1;
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while( left_bytes > 0 )
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{
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rv=write(sock->fd, &data[i], left_bytes);
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if( rv < 0 )
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{
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log_info("socket[%d] write() failure: %s, close socket now\n", sock->fd, strerror(errno));
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socket_term(sock);
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return -2;
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}
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else if( rv == left_bytes )
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{
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log_info("socket send %d bytes data over\n", bytes);
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return 0;
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}
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else
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{
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/* not send over this time, continue to send left data */
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i += rv;
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left_bytes -= rv;
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continue;
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}
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}
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return 0;
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}
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/* description: receive data from the socket
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* input args:
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* $sock : socket context pointer
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* $buf : socket receive data buffer
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* $size : socket receive data buffer size
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* $timeout: receive data time, <=0 will don't timeout
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* return value: <0: failure 0:ok
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*/
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int socket_recv(socket_ctx_t *sock, char *buf, int size, int timeout)
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{
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int rv = 0;
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fd_set rdset;
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int maxfd;
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if( !sock || !buf || size<= 0 )
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return -1;
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memset(buf, 0, size);
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maxfd = sock->fd;
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FD_ZERO(&rdset);
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FD_SET(sock->fd, &rdset);
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if( timeout <= 0 ) /* no timeout */
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{
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rv=select(maxfd+1, &rdset, NULL, NULL, NULL);
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}
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else
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{
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struct timeval tv;
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tv.tv_sec = timeout;
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tv.tv_usec = 0;
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rv=select(maxfd+1, &rdset, NULL, NULL, &tv);
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}
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if( rv < 0 )
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{
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log_error("select() on socket[%d] got error: %s\n", sock->fd, strerror(errno));
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return -2;
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}
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else if( rv == 0 )
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{
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log_error("select() on socket[%d] get timeout\n", sock->fd);
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return 0;
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}
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else
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{
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rv = read(sock->fd, buf, size);
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if( rv <= 0 )
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{
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log_error("socket[%d] read() failure or got disconnected: %s, close socket now\n", sock->fd, strerror(errno));
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socket_term(sock);
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return -2;
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}
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else
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{
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log_debug("socket[%d] receive %d bytes data\n", sock->fd, rv);
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return rv;
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}
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}
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}
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/*+-------------------------------------------------------------------+
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*| socket utils function |
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*+-------------------------------------------------------------------+*/
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/* description: set socket listen port as reusable, fix port already used bug */
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int socket_set_reuseaddr(int sockfd)
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{
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int opt = 1;
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int len = sizeof (int);
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if (setsockopt (sockfd, SOL_SOCKET, SO_REUSEADDR, (void *) &opt, len))
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{
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log_error("Set socket[%d] option SO_REUSEADDR failed:%s\n", sockfd, strerror(errno));
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return -1;
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}
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log_debug("Set socket[%d] option SO_REUSEADDR ok\n", sockfd);
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return 0;
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}
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/* set socket as non-block mode, common socket default work as block mode */
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int socket_set_nonblock(int sockfd)
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{
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int opts;
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/*
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* fcntl may set:
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*
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* EACCES, EAGAIN: Operation is prohibited by locks held by other
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* processes. Or, operation is prohibited because the file has
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* been memory-mapped by another process.
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* EBADF: fd is not an open file descriptor, or the command was F_SETLK
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* or F_SETLKW and the file descriptor open mode doesn't match
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* with the type of lock requested.
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* EDEADLK: It was detected that the specified F_SETLKW command would
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* cause a deadlock.
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* EFAULT: lock is outside your accessible address space.
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* EINTR: For F_SETLKW, the command was interrupted by a signal. For
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* F_GETLK and F_SETLK, the command was interrupted by a signal
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* before the lock was checked or acquired. Most likely when
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* locking a remote file (e.g. locking over NFS), but can
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* sometimes happen locally.
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* EINVAL: For F_DUPFD, arg is negative or is greater than the maximum
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* allowable value. For F_SETSIG, arg is not an allowable signal
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* number.
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* EMFILE: For F_DUPFD, the process already has the maximum number of
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* file descriptors open.
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* ENOLCK: Too many segment locks open, lock table is full, or a remote
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* locking protocol failed (e.g. locking over NFS).
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* EPERM: Attempted to clear the O_APPEND flag on a file that has the
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* append-only attribute set.
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*/
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opts = fcntl(sockfd, F_GETFL);
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if (opts < 0)
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{
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log_warn("fcntl() get socket options failure: %s\n", strerror(errno));
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return -1;
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}
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opts |= O_NONBLOCK;
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if (fcntl(sockfd, F_SETFL, opts) < 0)
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{
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log_warn("fcntl() set socket options failure: %s\n", strerror(errno));
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return -1;
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}
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log_debug("Set socket[%d] none blocking\n", sockfd);
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return opts;
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}
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/* set socket receive and send buffer size in linux kernel space */
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int socket_set_buffer(int sockfd, int rsize, int ssize)
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{
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int opt;
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socklen_t optlen = sizeof(opt);
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if(sockfd < 0)
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return -1;
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/* Get system default receive buffer size, Linux X86: 85K */
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if (getsockopt (sockfd, SOL_SOCKET, SO_RCVBUF, (char *) &opt, &optlen))
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{
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log_warn("getsockopt() get receive buffer failure: %s\n", strerror(errno));
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return -2;
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}
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/* Only when current receive buffer size larger than the default one will change it */
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if(rsize > opt)
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{
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opt = (int) rsize;
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if (setsockopt (sockfd, SOL_SOCKET, SO_RCVBUF, (char *) &opt, optlen))
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{
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log_warn("setsockopt() set receive buffer to %d failure: %s\n", opt, strerror(errno));
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return -2;
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}
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}
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/* Get system default send buffer size, Linux X86: 16K */
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if (getsockopt (sockfd, SOL_SOCKET, SO_SNDBUF, (char *) &opt, &optlen))
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{
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log_warn("getsockopt() get send buffer failure: %s\n", strerror(errno));
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return -3;
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}
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/* Only when current receive buffer size larger than the default one will change it */
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if(ssize > opt)
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{
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opt = (int) ssize;
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if (setsockopt (sockfd, SOL_SOCKET, SO_SNDBUF, (char *) &opt, optlen))
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{
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log_warn("setsockopt() set send buffer to %d failure: %s\n", opt, strerror(errno));
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return -3;
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}
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}
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log_info("Set socket[%d] RCVBUF size:%d SNDBUF size:%d\n", sockfd, rsize, ssize);
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return 0;
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}
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/*
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* Enable socket SO_KEEPALIVE, if the connection disconnected, any system call on socket
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* will return immediately and errno will be set to "WSAENOTCONN"
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*
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* keepalive is not program related, but socket related, * so if you have multiple sockets,
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* you can handle keepalive for each of them separately.
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*
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* Reference: http://tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/
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*/
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int socket_set_keepalive(int sockfd, int keepintvl, int keepcnt)
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{
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int opt;
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if(sockfd < 0)
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return -1;
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/* Enable the KEEPALIVE flag */
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opt = 1;
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if (setsockopt (sockfd, SOL_SOCKET, SO_KEEPALIVE, (char *) &opt, sizeof (opt)))
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{
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log_warn("setsockopt() enable SO_KEEPALIVE failure: %s\n", strerror(errno));
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return -2;
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}
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if(keepintvl || keepcnt)
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{
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/*
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* The tcp_keepidle parameter specifies the interval between the last data packet sent
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* (simple ACKs are not considered data) and the first keepalive probe; after the
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* connection is marked to need keepalive, this counter is not used any further.
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* ~ >: cat /proc/sys/net/ipv4/tcp_keepalive_time
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* 7200
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*/
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opt = 3; /* 3 seconds */
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if (setsockopt (sockfd, SOL_TCP, TCP_KEEPIDLE, (char *) &opt, sizeof (opt)))
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{
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log_error("setsockopt() set TCP_KEEPIDLE to %d seconds failure: %s\n", opt, strerror(errno));
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return -3;
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}
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if((opt=keepintvl) > 0)
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{
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/*
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* The tcp_keepintvl parameter specifies the interval between subsequential keepalive
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* probes, regardless of what the connection has exchanged in the meantime.
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* ~ >: cat /proc/sys/net/ipv4/tcp_keepalive_intvl
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* 75
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*/
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if (setsockopt (sockfd, SOL_TCP, TCP_KEEPINTVL, (char *) &opt, sizeof (opt)))
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{
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log_error("setsockopt() set TCP_KEEPINTVL to %d failure: %s\n", opt, strerror(errno));
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return -4;
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}
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}
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if((opt=keepcnt) > 0)
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{
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/*
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* The TCP_KEEPCNT option specifies the maximum number of unacknowledged probes to
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* send before considering the connection dead and notifying the application layer
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* probes to be sent. The value of TCP_KEEPCNT is an integer value between 1 and n,
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* where n is the value of the systemwide tcp_keepcnt parameter.
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* ~ >: cat /proc/sys/net/ipv4/tcp_keepalive_probes
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* 9
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*/
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if (setsockopt (sockfd, SOL_TCP, TCP_KEEPCNT, (char *) &opt, sizeof (opt)))
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{
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log_error("setsockopt() set TCP_KEEPCNT to %d failure: %s\n", opt, strerror(errno));
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return -5;
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}
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}
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}
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log_debug("Set socket[%d] KEEPINTVL:%d KEEPCNT:%d\n", sockfd, keepintvl, keepcnt);
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return 0;
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}
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/* Set open file description count to max */
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void set_socket_rlimit(void)
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{
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struct rlimit limit = {0};
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getrlimit(RLIMIT_NOFILE, &limit );
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limit.rlim_cur = limit.rlim_max;
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setrlimit(RLIMIT_NOFILE, &limit );
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log_info("set socket open fd max count to %d\n", limit.rlim_max);
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}
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