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POwhat is the meaning of error: dereferencing pointer to incomplete type
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copied!<p>Here is my program:</p> <pre><code>//SSL-Server-Client-Linkage-Broker.c #include <errno.h> #include <unistd.h> #include <malloc.h> #include <string.h> #include <asm/stat.h> #include <linux/fs.h> #include <linux/sched.h> #include <arpa/inet.h> #include <sys/socket.h> #include <sys/types.h> #include <netinet/in.h> #include <resolv.h> #include "openssl/ssl.h" #include "openssl/err.h" #define FAIL -1 int OpenConnection(const char *hostnamen, int portn) //for software house { int sd; struct hostent *host; struct sockaddr_in addr; if ( (host = gethostbyname(hostnamen)) == NULL ) { perror(hostnamen); abort(); } sd = socket(PF_INET, SOCK_STREAM, 0); bzero(&addr, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_port = htons(portn); addr.sin_addr.s_addr = *(long*)(host->h_addr); if ( connect(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 ) { close(sd); perror(hostnamen); abort(); } return sd; } SSL_CTX* InitServerCTX(void) { SSL_METHOD *method; SSL_CTX *ctx; OpenSSL_add_all_algorithms(); /* load & register all cryptos, etc. */ SSL_load_error_strings(); /* load all error messages */ method = SSLv2_server_method(); /* create new server-method instance */ ctx = SSL_CTX_new(method); /* create new context from method */ if ( ctx == NULL ) { ERR_print_errors_fp(stderr); abort(); } return ctx; } int OpenListener(int port) { int sd; struct sockaddr_in addr; sd = socket(PF_INET, SOCK_STREAM, 0); bzero(&addr, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_port = htons(port); addr.sin_addr.s_addr = INADDR_ANY; if ( bind(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 ) { perror("can't bind port"); abort(); } if ( listen(sd, 10) != 0 ) { perror("Can't configure listening port"); abort(); } return sd; } void LoadCertificates(SSL_CTX* ctx, char* CertFile, char* KeyFile) { /* set the local certificate from CertFile */ if ( SSL_CTX_use_certificate_file(ctx, CertFile, SSL_FILETYPE_PEM) <= 0 ) { ERR_print_errors_fp(stderr); abort(); } /* set the private key from KeyFile (may be the same as CertFile) */ if ( SSL_CTX_use_PrivateKey_file(ctx, KeyFile, SSL_FILETYPE_PEM) <= 0 ) { ERR_print_errors_fp(stderr); abort(); } /* verify private key */ if ( !SSL_CTX_check_private_key(ctx) ) { fprintf(stderr, "Private key does not match the public certificate\n"); abort(); } } void ShowCerts(SSL* ssl) { X509 *cert; char *line; cert = SSL_get_peer_certificate(ssl); /* Get certificates (if available) */ if ( cert != NULL ) { printf("Server certificates:\n"); line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0); printf("Subject: %s\n", line); free(line); line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0); printf("Issuer: %s\n", line); free(line); X509_free(cert); } else printf("No certificates.\n"); } char Servlet(SSL* ssl) /* Serve the connection -- threadable */ { char buf[1024]; char bufnew[1024]; char reply[1024]; int sd, bytes; const char* echo="Message received"; if ( SSL_accept(ssl) == FAIL ) /* do SSL-protocol accept */ ERR_print_errors_fp(stderr); else { ShowCerts(ssl); /* get any certificates */ bytes = SSL_read(ssl, buf, sizeof(buf)); /* get request */ if ( bytes > 0 ) { buf[bytes] = 0; printf("Client msg: %s\n", buf); strcpy (bufnew,buf); sprintf(reply, echo, buf); /* construct reply */ SSL_write(ssl, reply, strlen(reply)); /* send reply */ return bufnew; /* storing that in buffer for sending it to software house */ } else ERR_print_errors_fp(stderr); } sd = SSL_get_fd(ssl); /* get socket connection */ SSL_free(ssl); /* release SSL state */ close(sd); /* close connection */ } SSL_CTX* InitCTX(void) { SSL_METHOD *method; SSL_CTX *ctxn; OpenSSL_add_all_algorithms(); /* Load cryptos, et.al. */ SSL_load_error_strings(); /* Bring in and register error messages */ method = SSLv2_client_method(); /* Create new client-method instance */ ctxn = SSL_CTX_new(method); /* Create new context */ if ( ctxn == NULL ) { ERR_print_errors_fp(stderr); abort(); } return ctxn; } int main(int count, char *strings[]) { SSL_CTX *ctx; int server; char *portnum; int servern; char bufnew[1024]; int bytes; char *hostnamen, *portnumn; if ( count != 2 ) { printf("Usage: %s <portnum>\n", strings[0]); exit(0); } SSL_library_init(); portnum = strings[1]; ctx = InitServerCTX(); /* initialize SSL */ LoadCertificates(ctx, "mycert.pem", "mycert.pem"); /* load certs */ server = OpenListener(atoi(portnum)); /* create server socket */ while (1) { struct sockaddr_in addr; socklen_t len = sizeof(addr); SSL *ssl; int client = accept(server, (struct sockaddr*)&addr, &len); /* accept connection as usual */ printf("Connection: %s:%d\n",inet_ntoa(addr.sin_addr), ntohs(addr.sin_port)); ssl = SSL_new(ctx); /* get new SSL state with context */ SSL_set_fd(ssl, client); /* set connection socket to SSL state */ Servlet(ssl); /* service connection */ } close(server); /* close server socket */ SSL_CTX_free(ctx); /* release context */ /* ----------------------------- End of programmer/linkage broker connection ----------------------------------*/ /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Start of linkage broker/software house connection ~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/ SSL_CTX *ctxn; SSL *ssln; if ( count != 3 ) { printf("usage: %s <hostnamen> <portnumn>\n", strings[0]); exit(0); } SSL_library_init(); hostnamen = strings[1]; portnumn = strings[2]; ctxn = InitCTX(); server = OpenConnection(hostnamen, atoi(portnumn)); ssln = SSL_new(ctxn); // create new SSL connection state SSL_set_fd(ssln, server); // attach the socket descriptor if ( SSL_connect(ssln) == FAIL ) //perform the connection ERR_print_errors_fp(stderr); else { char *msg = bufnew; printf("Connected with %s encryption\n", SSL_get_cipher(ssln)); ShowCerts(ssln); // get any certs SSL_write(ssln, msg, strlen(msg)); // encrypt & send message bytes = SSL_read(ssln, bufnew, sizeof(bufnew)); // get reply & decrypt bufnew[bytes] = 0; printf("Received: \"%s\"\n", bufnew); SSL_free(ssln); // release connection state } close(server); // close socket SSL_CTX_free(ctxn); // release context return 0; } </code></pre> <p>when compiling it gives error in line</p> <pre><code>addr.sin_addr.s_addr = *(long*)(host->h_addr); </code></pre> <p>I tried to look hostent structure but couldn't find any solution.</p>

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