我有一个运行两个线程的代码，
第一个线程使用sender在recv()上等待数据，然后使用receiver将数据转发到send。
第二个线程使用receiver在recv()上等待数据，然后使用sender将数据转发到send。
这两个步骤必须并行工作。
假定发送方断开连接，第一个线程检测到此情况并关闭连接。
我如何告诉仍在等待接收器的第二个线程连接已关闭并且不需要进一步的通信？
recieve_packet已使用recv()实现。
send_packet已使用send()实现。
sender_fd是发送方的套接字文件描述符。
reciever_fd是接收者的套接字文件描述符。
void* sender_to_reciever(){
int t1;packet* p = malloc(sizeof(packet));
while((t1=recieve_packet(sender_fd,&p))!=0){
send_packet(reciever_fd,p);
}
close(sender_fd);
}
void* reciever_to_sender(){
int t1;packet* p = malloc(sizeof(packet));
while((t1=recieve_packet(reciever_fd,&p))!=0){
send_packet(sender_fd,p);
}
close(reciever_fd);
}
我不想更改send_packet和recieve_packet函数调用的实现。
如果任何一个while循环都退出，我尝试同时关闭sender_fd和reciever_d。但是，它没有用。
channel.c的代码，它同时处理发送者和接收者：-
#include "packets.c"
#define SERVER_PORT "8642"
#define QUEUE_LENGTH 10
void handle_connection(int);
void* sender_to_receiver();
void* receiver_to_sender();
int open_outgoing_connection(char*, char*);
int sender_fd;
int receiver_fd;
int main(int argc, char* argv[]){
int sock_fd,new_fd,rv,yes;yes=1;
struct addrinfo hints,*res;
struct sockaddr_storage client_addr;
socklen_t addr_size;
char client_details[INET6_ADDRSTRLEN];
struct sigaction sa;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;
if((rv=getaddrinfo(NULL, SERVER_PORT, &hints, &res))!=0){
printf("Error getaddrinfo : %s\n",gai_strerror(rv));
return 1;
}
if((sock_fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol))==-1){
printf("Error socket file descriptor\n");
return 1;
}
if(setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1){
printf("Error setsockopt\n");
return 1;
}
if(bind(sock_fd,res->ai_addr,res->ai_addrlen)==-1){
close(sock_fd);
printf("Error bind\n");
return 1;
}
if(listen(sock_fd, QUEUE_LENGTH)==-1){
printf("Error listen\n");
return 1;
}
freeaddrinfo(res);
sa.sa_handler = sigchld_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if(sigaction(SIGCHLD,&sa,NULL) == -1){
printf("Error sigaction\n");
return 1;
}
// Now we have prepared the socket(ip+port) for accepting incoming connections.
printf("Server PID : %d\n",getpid());
while(1){
addr_size = sizeof client_addr;
new_fd = accept(sock_fd,(struct sockaddr*)&client_addr, &addr_size);
if(new_fd==-1){
printf("Error Accepting Request %d\n",getpid());
return 1;
}
inet_ntop(client_addr.ss_family,get_in_addr((struct sockaddr*)&client_addr),client_details,sizeof client_details);
if(!fork()){ // Child Process
close(sock_fd);
printf("Connection Accepted From : %s by PID:%d\n",client_details,getpid());
handle_connection(new_fd);
exit(0);
}
}
return 1;
}
void handle_connection(int socket_sender){
packet* p = malloc(sizeof(packet));
int t1;
if((t1=receive_packet(socket_sender, &p))==0){
printf("Closed Connection\n");
}else{
int socket_receiver;
if((socket_receiver=open_outgoing_connection(p->destination_ip,p->destination_port))!=-1){
sender_fd = socket_sender;
receiver_fd = socket_receiver;
pthread_t str,rts;
str = pthread_self();
rts = pthread_self();
pthread_create(&str,NULL,sender_to_receiver,NULL);
pthread_create(&rts,NULL,receiver_to_sender,NULL);
pthread_join(str,NULL);
pthread_join(rts,NULL);
}else{
printf("Error Connecting to receiver\n");
}
}
}
void* sender_to_receiver(){
int t1;packet* p = malloc(sizeof(packet));
while((t1=receive_packet(sender_fd,&p))!=0){
printf("SENDER\n");
display_packet(p);
send_packet(receiver_fd,p);
}
printf("Sender Disconnected\n");
close(sender_fd);close(receiver_fd);
}
void* receiver_to_sender(){
int t1;packet* p = malloc(sizeof(packet));
while((t1=receive_packet(receiver_fd,&p))!=0){
printf("Receiver\n");
display_packet(p);
send_packet(sender_fd,p);
}
printf("Receiver Disconnected\n");
close(receiver_fd);close(sender_fd);
}
int open_outgoing_connection(char* ip, char* port){
int gai;
char server_ip[100];memset(server_ip,'\0',sizeof(server_ip));
struct addrinfo hints,*server;
memset(&hints,0,sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
int socket_fd;
if((gai=getaddrinfo(ip,port,&hints,&server)) != 0){
printf("GetAddrInfo Error: %s\n",gai_strerror(gai));
return -1;
}
if((socket_fd = socket(server->ai_family, server->ai_socktype, server->ai_protocol)) == -1){
printf("Socket Error\n");
return -1;
}
if(connect(socket_fd,server->ai_addr,server->ai_addrlen) == -1){
printf("Connect Error\n");
return -1;
}
freeaddrinfo(server);
inet_ntop(server->ai_family, get_in_addr((struct sockaddr*)server->ai_addr), server_ip, sizeof(server_ip));
printf("Connected to: %s\n",server_ip);
return socket_fd;
}
收款人代码：-
#include "packets.c"
#define QUEUE_LENGTH 10
void handle_connection(int);
int main(int argc, char* argv[]){
if(argc!=2){
printf("Enter PORT\n");
return 1;
}
int sock_fd,new_fd,rv,yes;yes=1;
struct addrinfo hints,*res;
struct sockaddr_storage client_addr;
socklen_t addr_size;
char client_details[INET6_ADDRSTRLEN];
struct sigaction sa;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;
if((rv=getaddrinfo(NULL, argv[1], &hints, &res))!=0){
printf("Error getaddrinfo : %s\n",gai_strerror(rv));
return 1;
}
if((sock_fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol))==-1){
printf("Error socket file descriptor\n");
return 1;
}
if(setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1){
printf("Error setsockopt\n");
return 1;
}
if(bind(sock_fd,res->ai_addr,res->ai_addrlen)==-1){
close(sock_fd);
printf("Error bind\n");
return 1;
}
if(listen(sock_fd, QUEUE_LENGTH)==-1){
printf("Error listen\n");
return 1;
}
freeaddrinfo(res);
sa.sa_handler = sigchld_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if(sigaction(SIGCHLD,&sa,NULL) == -1){
printf("Error sigaction\n");
return 1;
}
// Now we have prepared the socket(ip+port) for accepting incoming connections.
printf("Server PID : %d\n",getpid());
while(1){
addr_size = sizeof client_addr;
new_fd = accept(sock_fd,(struct sockaddr*)&client_addr, &addr_size);
if(new_fd==-1){
printf("Error Accepting Request %d\n",getpid());
return 1;
}
inet_ntop(client_addr.ss_family,get_in_addr((struct sockaddr*)&client_addr),client_details,sizeof client_details);
if(!fork()){ // Child Process
close(sock_fd);
printf("Connection Accepted From : %s by PID:%d\n",client_details,getpid());
handle_connection(new_fd);
exit(0);
}
close(new_fd);
}
return 1;
}
void handle_connection(int socket_fd){
int t1;packet* p = malloc(sizeof(packet));
while((t1=receive_packet(socket_fd,&p))!=0){
display_packet(p);
p->message = "ACK";
p->timestamp = get_time_in_ns();
send_packet(socket_fd,p);
}
printf("Sender Disconnected\n");
}
发件人代码：-
#include "packets.c"
#define CHANNEL_PORT "8642"
#define CHANNEL_IP "127.0.0.1"
int socket_fd;
char* destination_ip;
char* destination_port;
int number_of_packets;
char message[MESSAGE_BUFFER_LEN];
void prepare_packet_header(packet *p){
p->destination_ip=destination_ip;
p->destination_port=destination_port;
p->timestamp = get_time_in_ns();
p->length=0;
}
void divide_message_and_send_packets(){
if(number_of_packets>strlen(message)){
number_of_packets = strlen(message);
}
int indi_len = strlen(message)/number_of_packets;
int lm = 0;int i,j;
packet* all_packets[number_of_packets];
for(i=0;i<number_of_packets;i+=1)all_packets[i]=malloc(sizeof(packet));
// HANDSHAKE
prepare_packet_header(all_packets[0]);
all_packets[0]->message="SYN";
all_packets[0]->uid=-1;
send_packet(socket_fd,all_packets[0]);
// HANDSHAKE OVER
for(i=0;i<number_of_packets;i+=1){
// printf("Processing Packet: %d with message[%d:%d]\n",i,lm,lm+indi_len);
if(i!=number_of_packets-1){
char temp[indi_len+1];memset(temp,'\0', sizeof temp);
for(j=lm;j<lm+indi_len;j+=1)temp[j-lm]=message[j];
all_packets[i]->message = malloc(sizeof temp);
strcpy(all_packets[i]->message, temp);
all_packets[i]->uid = i;
}else{
char temp[strlen(message)-lm+1];memset(temp,'\0', sizeof temp);
for(j=lm;j<strlen(message);j+=1)temp[j-lm]=message[j];
all_packets[i]->message = malloc(sizeof temp);
strcpy(all_packets[i]->message, temp);
all_packets[i]->uid = i;
}
prepare_packet_header(all_packets[i]);lm+=indi_len;
display_packet(all_packets[i]);
send_packet(socket_fd,all_packets[i]);
}
}
void main(int argc,char* argv[]){
if(argc!=5){
printf("Enter DESTINATION_IP DESTINATION_PORT NUMBER_OF_PACKETS MESSAGE\n");
return;
}
strcpy(message,argv[4]);
number_of_packets=atoi(argv[3]);
destination_ip=malloc(sizeof argv[1] + 1);memset(destination_ip,'\0', sizeof destination_ip);
destination_port=malloc(sizeof argv[2] + 1);memset(destination_port,'\0', sizeof destination_port);
strcpy(destination_ip,argv[1]);
strcpy(destination_port,argv[2]);
int gai;
char server_ip[100];memset(server_ip,'\0',sizeof(server_ip));
struct addrinfo hints,*server;
memset(&hints,0,sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
if((gai=getaddrinfo(CHANNEL_IP,CHANNEL_PORT,&hints,&server)) != 0){
printf("GetAddrInfo Error: %s\n",gai_strerror(gai));
return;
}
if((socket_fd = socket(server->ai_family, server->ai_socktype, server->ai_protocol)) == -1){
printf("Socket Error\n");
}
if(connect(socket_fd,server->ai_addr,server->ai_addrlen) == -1){
printf("Connect Error\n");
}
freeaddrinfo(server);
inet_ntop(server->ai_family, get_in_addr((struct sockaddr*)server->ai_addr), server_ip, sizeof(server_ip));
printf("Connected to: %s\n",server_ip);
divide_message_and_send_packets();
while(1){} // busy wait taht simulates future work
}
packets.c的代码（包含与数据包有关的功能）：-
#include "helper.c"
typedef struct StupidAssignment{
long length;
char* destination_ip;
char* destination_port;
long timestamp;
long uid;
char* message;
}packet;
int receive_packet(int socket,packet** p1){
packet* p = *p1;
int remaining=0;int i;
int received=0;
long content_length=0;
remaining=11;
char buffer[MESSAGE_BUFFER_LEN];memset(buffer,'\0',sizeof(buffer));
while(remaining>0){
int t1 = recv(socket, buffer+received, remaining, 0);
if(t1==0)return 0;
remaining-=t1;
received+=t1;
}
content_length = read_long(buffer, received);
received=0;
remaining=content_length;p->length=content_length;
memset(buffer,'\0',sizeof(buffer));
while(remaining>0){
int t1 = recv(socket, buffer+received, remaining, 0);
if(t1==0)return 0;
remaining-=t1;
received+=t1;
}
char part[MESSAGE_BUFFER_LEN];memset(part,'\0',sizeof(part));int part_len=0;int nlmkr=0;
for(i=0;i<=content_length;i+=1){
if(buffer[i]=='\n' || i==content_length){
nlmkr+=1;
if(nlmkr==1) read_char(&(p->destination_ip), part, part_len);
else if(nlmkr==2) read_char(&(p->destination_port), part, part_len);
else if(nlmkr==3) p->timestamp = read_long(part, part_len);
else if(nlmkr==4) p->uid = read_long(part, part_len);
else if(nlmkr==6) read_char(&(p->message), part, part_len);
part_len=0;memset(part, '\0', sizeof part);
}else{
part[part_len++]=buffer[i];
}
}
return 1;
}
void send_packet(int socket,packet *p){
char temp[MESSAGE_BUFFER_LEN];memset(temp,'\0',sizeof temp);
strcat(temp,p->destination_ip);strcat(temp,"\n");
strcat(temp,p->destination_port);strcat(temp,"\n");
snprintf(temp+strlen(temp),100,"%ld\n",p->timestamp);
snprintf(temp+strlen(temp),100,"%ld\n",p->uid);
// write_long(p->timestamp,temp);strcat(temp,"\n");
// write_long(p->uid,temp);strcat(temp,"\n");
strcat(temp,"\n");
strcat(temp,p->message);
char buffer[MESSAGE_BUFFER_LEN];memset(buffer, '\0', sizeof buffer);
p->length = strlen(temp);
snprintf(buffer,100,"%10ld\n",strlen(temp));
strcat(buffer, temp);
sendAll(buffer,socket);
}
void display_packet(packet* p){
printf("----PACKET START----\n");
printf("%ld\n",p->length);
printf("%s\n",p->destination_ip);
printf("%s\n",p->destination_port);
printf("%ld\n",p->timestamp);
printf("%ld\n",p->uid);
printf("%s\n",p->message);
printf("----PACKET END-----\n");
}
helper.c的代码（所有其他代码使用某些功能）：-
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <poll.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#include <time.h>
#include <sys/stat.h>
#include <ctype.h>
#include <fcntl.h>
#include <pthread.h>
#define MESSAGE_BUFFER_LEN 20480
void read_char(char** into, char* from, int length){
*into = malloc(length+1);memset(*into, '\0', sizeof *into);
strcpy(*into, from);
// printf("%s\n",into);
}
long read_long(char* from, int length){
int i;long temp=0;
for(i=0;i<length;i+=1){
if(isdigit(*(from+i))){
temp=temp*10;temp+=(long)(*(from+i) - '0');
}
}
return temp;
}
void write_long(long t1,char* m){
int mkr=0;
char temp[100];memset(temp,'\0',sizeof temp);
while(t1!=0){
temp[mkr] = ((int)(t1%10)) + '0';
t1 = t1/10;
}
for(mkr=strlen(temp)-1;mkr>=0;mkr-=1){
*(m+strlen(m))=temp[mkr];
}
}
void *get_in_addr(struct sockaddr* sa){
if(sa->sa_family == AF_INET){
return &(((struct sockaddr_in *)sa)->sin_addr);
}else{
return &(((struct sockaddr_in6*)sa)->sin6_addr);
}
}
void sigchld_handler(int s){
int saved_errno=errno;
while(waitpid(-1, NULL, WNOHANG) > 0);
errno = saved_errno;
}
int sendAll(char* data_to_send,int socket_fd){
int bytesleft = strlen(data_to_send);
int total=0;int n;
while(bytesleft>0){
n = send(socket_fd,data_to_send + total, bytesleft, 0);
if(n==-1)break;
total+=n;
bytesleft-=n;
}
return n==-1?-1:0;
}
long get_time_in_ns(){
struct timespec start;clock_gettime(CLOCK_REALTIME,&start);
long ct = ((long)start.tv_sec)*1e9 + ((long)start.tv_nsec);
return ct;
}
根本没有记录代码。
答案 0 :(得分：1)
对于TCP，请在套接字上调用shutdown。要更完整：
shutdown。如果您需要在拆解过程中致电shutdown，请执行此操作。如果不是，则在完成拆卸过程（如果有）后，shutdown双向连接。close，直到您可以100％确认没有线程正在或可能正在尝试访问套接字。这非常重要。对于UDP，将数据报发送到套接字。当线程接收到虚拟数据报时，它将解除阻塞。