UDP communication, message queue and socket? -
i have client sends message server; server, before receiving data, creates child process; when client try connect server, server sends on message queue data client; child read message queue , send response client; program in not complete, because i'm doing tests; when run program, client sending request , receives response data; put printf in child code, , doesn't print anything; child executes sendto, don't understand if child readed message queue..
server code:
struct msgbuf{ long mtype; struct sockaddr_in s; }; void err_exit(char* str) { perror(str); exit(exit_failure); } int get_msg_queue() { key_t key = ftok(".",'b'); if(key == -1) err_exit("ftok"); int qid = msgget(key,ipc_creat | 0666); if(qid == -1) err_exit("msgget"); return qid; } void child_job(int qid, pid_t pid) { (void)pid; struct sockaddr_in addr; header p; int sockfd; struct msgbuf msg; msg.mtype = 1; memset((void *)&addr, 0, sizeof(addr)); addr.sin_family = af_inet; addr.sin_addr.s_addr = htonl(inaddr_any); addr.sin_port = htons(0); if ((sockfd = socket(af_inet, sock_dgram, 0)) < 0) err_exit("errore in socket"); if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) { perror("error in bind"); exit(1); } if(msgrcv(qid,&msg,sizeof(msg) - sizeof(long),0,0) == -1) err_exit("msgrcv"); printf("received data\n"); p.v[0] = 1; p.v[1] = 1; p.data[0] = 'a'; p.data[1] = '\0'; printf("tring sending\n"); if (sendto(sockfd, &p, sizeof(header), 0, (struct sockaddr *)&addr, sizeof(addr)) < 0) { err_exit("sendto"); } printf("sended request\n"); exit(exit_success); } void initialize_processes(int qid) { pid_t pid; pid = fork(); if(pid == -1) err_exit("fork"); if(pid == 0) child_job(qid,getpid()); } void write_on_queue(struct sockaddr_in addr, int qid) { struct msgbuf msg; size_t size = sizeof(addr) - sizeof(long); msg.mtype = 1; msg.s = addr; if(msgsnd(qid,&msg,size,0) == -1) err_exit("msgsnd"); } void listen_request(int qid) { int sockfd; struct sockaddr_in addr; socklen_t l = sizeof(addr); header p; memset((void *)&addr, 0, sizeof(addr)); addr.sin_family = af_inet; addr.sin_addr.s_addr = htonl(inaddr_any); addr.sin_port = htons(servport); /* numero di porta del server */ if ((sockfd = socket(af_inet, sock_dgram, 0)) < 0) err_exit("errore in socket"); if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) { printf("padre: erorre bind\n"); perror("errore in bind"); exit(1); } printf("listening request\n"); if ((recvfrom(sockfd, &p, maxline, 0, (struct sockaddr *)&addr, &l)) < 0){ printf("errno code: %d\n",errno); err_exit("recvfrom\n"); } write_on_queue(addr,qid); printf("write on queue\n"); return; } int main(int argc, char*argv[]) { (void) argc, (void) argv; int qid; qid = get_msg_queue(); initialize_processes(qid); listen_request(qid); printf("server listened request\n"); wait(null); exit(exit_success); } client code:
void err_exit(char* str) { perror(str); exit(exit_failure); } //header typedef 2 integers , buffer 2 carachtet int request_to_server(int sockfd,header* x,struct sockaddr_in addr) { int n; if(sendto(sockfd, null, 0, 0, (struct sockaddr *) &addr, sizeof(addr)) < 0) err_exit("sendto\n"); printf("client waiting response\n"); n = recvfrom(sockfd,x,sizeof(header),0,null,null); if (n < 0) { perror("errore in recvfrom"); exit(1); } if(n > 0) { printf("client connected!\n"); } return 1; } int main(int argc, char *argv[ ]) { int sockfd; struct sockaddr_in servaddr; header p; if (argc != 2) { fprintf(stderr, "utilizzo: daytime_clientudp <indirizzo ip server>\n"); exit(1); } if((sockfd = socket(af_inet, sock_dgram, 0)) < 0) { /* crea il socket */ perror("errore in socket"); exit(1); } memset((void *)&servaddr, 0, sizeof(servaddr)); servaddr.sin_family = af_inet; servaddr.sin_port = htons(servport); if(inet_pton(af_inet, argv[1], &servaddr.sin_addr) <= 0) { err_exit("error in inet_pton %s"); } if(!request_to_server(sockfd,&p,servaddr)) err_exit("request server"); printf("received ack!\n"); for(;;) ; exit(exit_success); }
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