p2p通信的简单实现（c语言）

#include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <arpa/inet.h> #include <sys/socket.h> #include <netinet/in.h> #include <string.h> #include <stdbool.h> #include <time.h> #define MAXSIZE 1024 struct client { unsigned short token; unsigned short port; unsigned int ip; time_t time; struct client *next; }; int size = 0;//list pthread_mutex_t mutex; struct client* head = NULL; void Insert(struct sockaddr_in * cli, int token); struct client* Search(int token); void Delete(int token); void *thread(void *vargp); void parsemessage(char * buf, int fd, struct sockaddr_in * cli); void Compare(void); int main() { pthread_t id; int ret; int fd = socket(PF_INET, SOCK_DGRAM, 0); if( fd == -1 )perror("create failed!"),exit( -1 ); struct sockaddr_in ser_addr; struct sockaddr_in cli_addr; ser_addr.sin_family = PF_INET; ser_addr.sin_port = htons( 12345 ); ser_addr.sin_addr.s_addr = htonl( INADDR_ANY ); if(bind(fd, (struct sockaddr*)&ser_addr, sizeof(ser_addr)) < 0) { perror("bind failed!1"); exit( -1 ); } else printf( "bind success!\n" ); int cli_len = sizeof(cli_addr); memset(&cli_addr, 0, cli_len); cli_addr.sin_family = PF_INET; char buf[MAXSIZE]; memset(&cli_addr, 0, sizeof(cli_addr)); ret = pthread_create(&id, NULL, (void*)thread, NULL); if(ret != 0) { printf("Create thread error!\r\n"); exit(1); } while(1) { printf("wait client login......\n"); if((recvfrom(fd, buf, MAXSIZE, 0, (struct sockaddr*)&cli_addr, &cli_len))<0) { perror("recv failed!1"); break; } parsemessage(buf, fd, &cli_addr); } close(fd); return 0; } void parsemessage(char* buf, int fd, struct sockaddr_in * cli) { unsigned short token; memcpy(&token, buf, 2); token = ntohs(token); struct client *p; p = Search(token); if(p != NULL) { struct sockaddr_in addr; addr.sin_family = PF_INET; addr.sin_port = htons(p->port); addr.sin_addr.s_addr = htonl(p->ip); memset(buf, 0, MAXSIZE); token = htons(token); memcpy(buf, &token, 2); memcpy(buf+2, &addr.sin_port, 2); memcpy(buf+4, &addr.sin_addr.s_addr, 4); if(sendto(fd, buf, 8, 0, (struct sockaddr*)cli, sizeof(*cli))<0) { perror("send failed!1"); exit(0); } memset(buf, 0, MAXSIZE); memcpy(buf, &token, 2); memcpy(buf+2, &(cli->sin_port), 2); memcpy(buf+4, &(cli->sin_addr.s_addr), 4); if(sendto(fd, buf, 8, 0, (struct sockaddr*)&addr, sizeof(addr))<0) { perror("send failed!2"); exit(0); } pthread_mutex_lock(&mutex); Delete(token); pthread_mutex_unlock(&mutex); return; } if(p == NULL) { pthread_mutex_lock(&mutex); Insert(cli,token); pthread_mutex_unlock(&mutex); unsigned short token1; token1 = 0x0000; char buf1[30] = "received!"; token1 = htons(token1); memcpy(buf, &token1, 2); memcpy(buf+2, buf1, 12); if(sendto(fd, buf, 14, 0, (struct sockaddr*)cli, sizeof(*cli))<0) { perror("send failed!3"); exit(1); } } } void *thread(void *vargp) { // int i ; while(1) { Compare(); sleep(5); } } void Compare(void) { struct client *p; time_t t = time(NULL); p = head; int n = 0; while(p) { if((n = (int)difftime(t, p->time)) > 100) { pthread_mutex_lock(&mutex); Delete( p->token ); pthread_mutex_unlock(&mutex); } p = p->next; } } void Insert(struct sockaddr_in * cli, int token) { struct client *p; time_t t = time(NULL); p = (struct client*)malloc(sizeof(struct client)); p->port = ntohs(cli->sin_port); p->ip = ntohl(cli->sin_addr.s_addr); p->token = token; p->time = t; if(head == NULL) { p->next = NULL; head = p; p = NULL; } else { p->next = head; head = p; p = NULL; } size++; } struct client* Search(int token) { struct client *p; p = head; while(p) { if(p->token == token) { return p; } p = p->next; } return p; } void Delete(int token) { struct client *p; struct client *p1; p = Search(token); int i; p1 = head; for(i = 1; i < size; i++) { if(p1->next == p) { p1->next = p->next; free(p); p = NULL; p1 = NULL; return; } p1 = p1->next; } free(p); p = NULL; p1 = NULL; head = NULL; }