There is a server and many clients. Clients send their names to the server. Then the client can write the name of a client and a message. The server should send this message to the client whose name the client wrote. The server has a list of clients, but I cannot find a client and send this email.

struct client { struct client* next; char name[1024]; int sd; }; struct client* head; void add(int id, char* n) { struct client* temp; temp = (struct client*)malloc(sizeof(struct client)); strcpy(temp -> name, n); temp -> sd = id; temp -> next = head; head = temp; } bool findsd(int id) { struct client* cur = head; if(head == NULL) { return NULL; } while(cur -> sd != id) { if(cur -> next == NULL) { return false; } else { cur = cur -> next; } } return true; } struct client* find(char* n) { struct client* cur = head; if(head == NULL) { return NULL; } while(strcmp(cur -> name, n) != 0) { if(cur -> next == NULL) { return NULL; } else { cur = cur -> next; } } return cur; } void printList() { struct client* ptr = head; while(ptr != NULL) { printf("[(%s, %d)]\n", ptr -> name, ptr -> sd); ptr = ptr -> next; } } void *connection_handler(void *socket_desc) { int sock = *(int*)socket_desc; struct client* c; int num, i = 0; char r[1024], n[100]; num = recv(sock, r, sizeof(r), 0); if(num <= 0) { printf("Error\n"); //break; } else if (num == 0) { printf("Connection closed\n"); } r[num] = '\0'; if(!findsd(sock)) { add(sock, r); printList(); } else{ while(r[i] != ' ') { n[i] = r[i]; i++; } n[i] = '\0'; } if((c = find(n)) != NULL) { send(c -> sd, r, sizeof(r), 0); } } int main() { int sd, csd; int* new_sock; char buf[1024]; char b[1024]; int* d, *c; int num; struct sockaddr_in sAddr; struct sockaddr_storage sStorage; socklen_t addr_size; sd = socket(PF_INET, SOCK_STREAM, 0); sAddr.sin_family = AF_INET; sAddr.sin_port = htons(8888); sAddr.sin_addr.s_addr = inet_addr("127.0.0.1"); memset(sAddr.sin_zero, '\0', sizeof sAddr.sin_zero); bind(sd, (struct sockaddr *) &sAddr, sizeof(sAddr)); if( listen(sd, 5) == 0 ) printf("Listening\n"); else printf("Error\n"); addr_size = sizeof(struct sockaddr_in); int j, i = 0; new_sock = malloc(5); while( csd = accept(sd, (struct sockaddr *) &sStorage, &addr_size)) { puts("Connection accepted"); pthread_t sniffer_thread; new_sock[i] = csd; if( pthread_create( &sniffer_thread , 0 ,connection_handler , (void*) (new_sock + i)) < 0) { perror("could not create thread"); return 1; } puts("Handler assigned"); i++; } }

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