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[/] [or1k/] [trunk/] [ecos-2.0/] [packages/] [net/] [ns/] [dns/] [v2_0/] [src/] [dns.c] - Rev 1254
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//============================================================================= // // dns.c // // DNS client code // //============================================================================= //####ECOSGPLCOPYRIGHTBEGIN#### // ------------------------------------------- // This file is part of eCos, the Embedded Configurable Operating System. // Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc. // // eCos is free software; you can redistribute it and/or modify it under // the terms of the GNU General Public License as published by the Free // Software Foundation; either version 2 or (at your option) any later version. // // eCos is distributed in the hope that it will be useful, but WITHOUT ANY // WARRANTY; without even the implied warranty of MERCHANTABILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License // for more details. // // You should have received a copy of the GNU General Public License along // with eCos; if not, write to the Free Software Foundation, Inc., // 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. // // As a special exception, if other files instantiate templates or use macros // or inline functions from this file, or you compile this file and link it // with other works to produce a work based on this file, this file does not // by itself cause the resulting work to be covered by the GNU General Public // License. However the source code for this file must still be made available // in accordance with section (3) of the GNU General Public License. // // This exception does not invalidate any other reasons why a work based on // this file might be covered by the GNU General Public License. // // Alternative licenses for eCos may be arranged by contacting Red Hat, Inc. // at http://sources.redhat.com/ecos/ecos-license/ // ------------------------------------------- //####ECOSGPLCOPYRIGHTEND#### //============================================================================= //#####DESCRIPTIONBEGIN#### // // Author(s): andrew.lunn // Contributors:andrew.lunn, jskov // Date: 2001-09-18 // Description: Provides DNS lookup as per RFC 1034/1035. // // Note: Does only support A and PTR lookups. Maybe add for other // types as well? // // parse_answer() only returns the first found record. // // Add tracing and assertions. // //####DESCRIPTIONEND#### // //============================================================================= #include <pkgconf/system.h> #ifdef CYGPKG_KERNEL # include <pkgconf/kernel.h> # include <cyg/kernel/kapi.h> #endif #include <cyg/hal/drv_api.h> #include <cyg/infra/cyg_type.h> #include <cyg/infra/cyg_trac.h> /* Tracing support */ #include <netdb.h> #include <sys/time.h> #include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <ctype.h> #include <unistd.h> #include <stdio.h> #include <string.h> #include <stdlib.h> #include <cyg/ns/dns/dns_priv.h> static short id = 0; /* ID of the last query */ static int s = -1; /* Socket to the DNS server */ static cyg_drv_mutex_t dns_mutex; /* Mutex to stop multiple queries as once */ static cyg_ucount32 ptdindex; /* Index for the per thread data */ static char * domainname=NULL; /* Domain name used for queries */ /* Allocate space for string of length len. Return NULL on failure. */ static inline char* alloc_string(int len) { return malloc(len); } static inline void free_string(char* s) { free(s); } /* Deallocate the memory taken to hold a hent structure */ static void free_hent(struct hostent * hent) { if (hent->h_name) { free_string(hent->h_name); } if (hent->h_addr_list) { int i = 0; while (hent->h_addr_list[i]) { free(hent->h_addr_list[i]); i++; } free(hent->h_addr_list); } free(hent); } /* Allocate hent structure with room for one in_addr. Returns NULL on failure. */ static struct hostent* alloc_hent(void) { struct hostent *hent; hent = malloc(sizeof(struct hostent)); if (hent) { memset(hent, 0, sizeof(struct hostent)); hent->h_addr_list = malloc(sizeof(char *)*2); if (!hent->h_addr_list) { free_hent(hent); return NULL; } hent->h_addr_list[0] = malloc(sizeof(struct in_addr)); if (!hent->h_addr_list[0]) { free_hent(hent); return NULL; } hent->h_addr_list[1] = NULL; } return hent; } /* Thread destructor used to free stuff stored in per-thread data slot. */ static void thread_destructor(CYG_ADDRWORD data) { struct hostent *hent; hent = (struct hostent *)cyg_thread_get_data(ptdindex); if (hent) free_hent(hent); return; data=data; } /* Store the hent away in the per-thread data. */ static void store_hent(struct hostent *hent) { // Prevent memory leaks by setting a destructor to be // called on thread exit to free per-thread data. cyg_thread_add_destructor( &thread_destructor, 0 ); cyg_thread_set_data(ptdindex, (CYG_ADDRWORD)hent); } /* If there is an answer to an old query, free the memory it uses. */ static void free_stored_hent(void) { struct hostent *hent; hent = (struct hostent *)cyg_thread_get_data(ptdindex); if (hent) { free_hent(hent); cyg_thread_set_data(ptdindex, (CYG_ADDRWORD)NULL); cyg_thread_rem_destructor( &thread_destructor, 0 ); } } /* Send the query to the server and read the response back. Return -1 if it fails, otherwise put the response back in msg and return the length of the response. */ static int send_recv(char * msg, int len, int msglen) { struct dns_header *dns_hdr; struct timeval timeout; int finished = false; int backoff = 1; fd_set readfds; int written; int ret; CYG_REPORT_FUNCNAMETYPE( "send_recv", "returning %d" ); CYG_REPORT_FUNCARG3( "msg=%08x, len=%d, msglen", msg, len, msglen ); CYG_CHECK_DATA_PTR( msg, "msg is not a valid pointer!" ); dns_hdr = (struct dns_header *) msg; do { written = write(s, msg, len); if (written < 0) { ret = -1; break; } FD_ZERO(&readfds); FD_SET(s, &readfds); timeout.tv_sec = backoff; timeout.tv_usec = 0; backoff = backoff << 1; ret = select(s+1, &readfds, NULL, NULL, &timeout); if (ret < 0) { ret = -1; break; } /* Timeout */ if (ret == 0) { if (backoff > 16) { h_errno = TRY_AGAIN; ret = -1; break; } } if (ret == 1) { ret = read(s, msg, msglen); if (ret < 0) { ret = -1; break; } /* Reply to an old query. Ignore it */ if (ntohs(dns_hdr->id) != (id-1)) { continue; } finished = true; } } while (!finished); CYG_REPORT_RETVAL( ret ); return ret; } /* Include the DNS client implementation code */ #include <cyg/ns/dns/dns_impl.inl> /* Initialise the resolver. Open a socket and bind it to the address of the server. return -1 if something goes wrong, otherwise 0. If we are being called a second time we have to be careful to allow any ongoing lookups to finish before we close the socket and connect to a different DNS server. The danger here is that we may have to wait for upto 32 seconds if the DNS server is down. */ int cyg_dns_res_init(struct in_addr *dns_server) { struct sockaddr_in server; struct servent *sent; static int init =0; CYG_REPORT_FUNCNAMETYPE( "cyg_dns_res_init", "returning %d" ); CYG_REPORT_FUNCARG1( "dns_server=%08x", dns_server ); CYG_CHECK_DATA_PTR( dns_server, "dns_server is not a valid pointer!" ); if (init) { cyg_drv_mutex_lock(&dns_mutex); cyg_thread_free_data_index(ptdindex); if (s >= 0) { close(s); } } else { init = 1; cyg_drv_mutex_init(&dns_mutex); cyg_drv_mutex_lock(&dns_mutex); } s = socket(PF_INET, SOCK_DGRAM, 0); if (s < 0) { cyg_drv_mutex_unlock(&dns_mutex); CYG_REPORT_RETVAL( -1 ); return -1; } sent = getservbyname("domain", "udp"); if (sent == (struct servent *)0) { s = -1; cyg_drv_mutex_unlock(&dns_mutex); CYG_REPORT_RETVAL( -1 ); return -1; } memcpy((char *)&server.sin_addr, dns_server, sizeof(server.sin_addr)); server.sin_port = sent->s_port; server.sin_family = AF_INET; server.sin_len = sizeof(server); if (connect(s, (struct sockaddr *)&server, sizeof(server)) < 0) { s = -1; cyg_drv_mutex_unlock(&dns_mutex); CYG_REPORT_RETVAL( -1 ); return -1; } ptdindex = cyg_thread_new_data_index(); cyg_drv_mutex_unlock(&dns_mutex); CYG_REPORT_RETVAL( 0 ); return 0; }
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