dns_impl.inl

嵌入式操作系统ECOS的网络开发包

        ptr += sizeof(struct resource_record) - sizeof(rr.rdata) + ntohs(rr.rdlength);
        dns_hdr->ancount--;
    }

    /* If we found one. decode it */
    if (dns_hdr->ancount > 0) {
        hent = alloc_hent();
        if (!hent) 
            return NULL;
        switch (rr_type) {
        case DNS_TYPE_A:
            hent->h_name = real_name(msg, qname);
            if (!hent->h_name) {
                free_hent(hent);
                return NULL;
            }
            memcpy(hent->h_addr_list[0], rr_p->rdata, sizeof(struct in_addr));
            hent->h_addrtype = AF_INET;
            hent->h_length = sizeof(struct in_addr);
            return hent;
        case DNS_TYPE_PTR:
            hent->h_name = real_name(msg, rr_p->rdata);
            if (!hent->h_name) {
                free_hent(hent);
                return NULL;
            }
            hent->h_addrtype = AF_INET;
            hent->h_length = sizeof(struct in_addr);
            return hent;
        default:
            free_hent(hent);
        }
    }
    h_errno = NO_DATA;
    return NULL;
}

/* Given an address, find out the hostname. */
struct hostent *
gethostbyaddr(const char *addr, int len, int type)
{
    unsigned char msg[MAXDNSMSGSIZE];
    char hostname[40];
    struct hostent * hent;

    CYG_REPORT_FUNCNAMETYPE( "gethostbyaddr", "returning %08x" );
    CYG_REPORT_FUNCARG3( "addr=%08x, len=%d, type=%d", addr, len, type );

    if ( !addr || 0 == len) {
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }

    CYG_CHECK_DATA_PTR( addr, "addr is not a valid pointer!" );

    /* Has the socket to the DNS server been opened? */
    if (s < 0) {
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }

    /* See if there is an answer to an old query. If so free the memory
       it uses. */
    free_stored_hent();

    /* Only IPv4 addresses accepted */
    if ((type != AF_INET) || (len != sizeof(struct in_addr))) {
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }

    cyg_drv_mutex_lock(&dns_mutex);

    /* Build the 'hostname' we want to lookup. */
    sprintf(hostname, "%d.%d.%d.%d.IN-ADDR.ARPA.",
            (unsigned char)addr[3],
            (unsigned char)addr[2],
            (unsigned char)addr[1],
            (unsigned char)addr[0]);
  
    memset(msg, 0, sizeof(msg));
  
    /* Build a PTR type request using the hostname */
    len = build_query(msg, hostname, DNS_TYPE_PTR);
    if (len < 0) {
        cyg_drv_mutex_unlock(&dns_mutex);
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }

    /* Send the request and wait for an answer */
    len = send_recv(msg, len, sizeof(msg));
    if (len < 0) {
        cyg_drv_mutex_unlock(&dns_mutex);
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }

    /* Fill in the missing address */
    hent = parse_answer(msg, DNS_TYPE_PTR);
    if (hent) {
        memcpy(hent->h_addr_list[0], addr, sizeof(struct in_addr));
        store_hent(hent);
    }
    cyg_drv_mutex_unlock(&dns_mutex);

    CYG_REPORT_RETVAL( hent );
    return hent;
}

/* Given a hostname find out the IP address */
struct hostent *
gethostbyname(const char * hostname)
{
    unsigned char msg[MAXDNSMSGSIZE];
    char name[256];
    struct hostent *hent;
    int len;

    CYG_REPORT_FUNCNAMETYPE( "gethostbyname", "returning %08x" );
    CYG_REPORT_FUNCARG1( "hostname=%08x", hostname );

    if ( !hostname ) {
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }

    CYG_CHECK_DATA_PTR( hostname, "hostname is not a valid pointer!" );

    /* Has the socket to the DNS server been opened? */
    if (s < 0) {
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }

    /* See if there is an answer to an old query. If so free the memory
       it uses */
    free_stored_hent();
  
    if (!valid_hostname(hostname)) {
        /* It could be a dot address */
        hent = dot_hostname(hostname);
        store_hent(hent);
        CYG_REPORT_RETVAL( hent );
        return hent;
    }

    cyg_drv_mutex_lock(&dns_mutex);

    /* First try the name as passed in */
    memset(msg, 0, sizeof(msg));
    len = build_query(msg, hostname, DNS_TYPE_A);
    if (len < 0) {
        cyg_drv_mutex_unlock(&dns_mutex);
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }
  
    /* Send the query and wait for an answer */
    len = send_recv(msg, len, sizeof(msg));
    if (len < 0) {
        cyg_drv_mutex_unlock(&dns_mutex);
        CYG_REPORT_RETVAL( NULL );
        return NULL;
    }
  
    /* Decode the answer */
    hent = parse_answer(msg, DNS_TYPE_A);
    if (hent) {
        cyg_drv_mutex_unlock(&dns_mutex); 
        store_hent(hent);
        CYG_REPORT_RETVAL( hent );
        return hent;
    }

    /* If no match, try appending the domainname if we have one */
    if (domainname) {
        if ((strlen(hostname) + strlen(domainname)) > 254) {
            h_errno = NO_RECOVERY;
            cyg_drv_mutex_unlock(&dns_mutex);
            CYG_REPORT_RETVAL( NULL );
            return NULL;
        }
        strcpy(name, hostname);
        strcat(name, ".");
        strcat(name, domainname);
    
        memset(msg, 0, sizeof(msg));
        len = build_query(msg, name, DNS_TYPE_A);
        if (len < 0) {
            cyg_drv_mutex_unlock(&dns_mutex);
            CYG_REPORT_RETVAL( NULL );
            return NULL;
        }
    
        /* Send the query and wait for an answer */
        len = send_recv(msg, len, sizeof(msg));
        if (len < 0) {
            cyg_drv_mutex_unlock(&dns_mutex);
            CYG_REPORT_RETVAL( NULL );
            return NULL;
        }
    
        /* Decode the answer */
        hent = parse_answer(msg, DNS_TYPE_A);
    }

    cyg_drv_mutex_unlock(&dns_mutex); 
    store_hent(hent);
    CYG_REPORT_RETVAL( hent );
    return hent;
}

/* Set the domain names, as used by the DNS server */
int
setdomainname(const char *name, size_t len)
{
    char * ptr;

    CYG_REPORT_FUNCNAMETYPE( "setdomainname", "returning %d" );
    CYG_REPORT_FUNCARG2( "name=%08x, len=%d", name, len );

    if ((len < 0) || (len > 255)) {
        h_errno = NO_RECOVERY;
        CYG_REPORT_RETVAL( -1 );
        return -1;
    }
    if (len != 0) {
        CYG_CHECK_DATA_PTR( name, "name is not a valid pointer!" );
        ptr = alloc_string(len+1);
        if (!ptr) {         
            CYG_REPORT_RETVAL( -1 );
            return -1;
        } 
        memcpy(ptr, name, len);
        ptr[len]=0;
    } else {
        ptr = NULL;
    }
  
    if (domainname) {
        free_string(domainname);
    }
    domainname = ptr;
    CYG_REPORT_RETVAL( 0 );
    return 0;
}

/* Return the domain name as used by the DNS server */
int
getdomainname(char *name, size_t len)
{
    CYG_REPORT_FUNCNAMETYPE( "getdomainname", "returning %d" );
    CYG_REPORT_FUNCARG2( "name=%08x, len=%d", name, len );

    if ( !name || 0 == len) {
        CYG_REPORT_RETVAL( -1 );
        return -1;
    }

    CYG_CHECK_DATA_PTR( name, "name is not a valid pointer!" );

    /* No domainname set, return a 0 */
    if (!domainname) {
        if (len == 0) {
            h_errno = HOST_NOT_FOUND;
            CYG_REPORT_RETVAL( -1 );
            return -1;
        }
        name[0]='\0';
    } else {
        if ((strlen(domainname) + 1) > len) {
            h_errno = NO_RECOVERY;
            CYG_REPORT_RETVAL( -1 );
            return -1;
        }
        strncpy(name, domainname, len);
    }
    CYG_REPORT_RETVAL( 0 );
    return 0;
}

int h_errno = DNS_SUCCESS;

const char*
hstrerror(int err)
{
    CYG_REPORT_FUNCNAMETYPE( "hstrerror", "returning %08x" );
    CYG_REPORT_FUNCARG1( "err=%d", err );

    switch (err) {
    case DNS_SUCCESS:
        return "No error";
    case HOST_NOT_FOUND:
        return "No such host is known";
    case TRY_AGAIN:
        return "Timeout";
    case NO_RECOVERY:
        return "Server failure or invalid input";
    case NO_DATA:
        return "No data for type";
    default:
        return "Uknown error";
    }
}

//-----------------------------------------------------------------------------
#endif // CYGONCE_NS_DNS_DNS_IMPL_H
// End of dns_impl.h