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| -rw-r--r-- | src/dnsclient.c | 208 | ||||
| -rw-r--r-- | src/dnsclient.h | 32 |
2 files changed, 240 insertions, 0 deletions
diff --git a/src/dnsclient.c b/src/dnsclient.c new file mode 100644 index 0000000..7bf313d --- /dev/null +++ b/src/dnsclient.c @@ -0,0 +1,208 @@ +/* $Id: dnsclient.c,v 1.1 2002-05-23 04:40:06 rjkaes Exp $ + * + * Create the dnsserver child process, and then include functions to + * retrieve IP addresses or host names. These functions are required + * since the traditional gethostbyaddr() and getaddrbyname() functions + * are not thread reentrant. By spawning a child process the blocking + * has been moved outside the threads. + * + * Copyright (C) 2002 Robert James Kaes (rjkaes@flarenet.com) + * + * This program 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. + * + * This program 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. + */ + +#include "tinyproxy.h" + +#include "dnsclient.h" +#include "heap.h" +#include "log.h" +#include "network.h" +#include "text.h" + +/* + * Static variable which holds the "dnsserver" process. + */ +static pid_t dnsserver_process; + +/* + * Hold the location of the Unix socket for client communication. + */ +static char* unix_socket_loc; + +/* + * Fork a copy of the "dnsserver" program. Two arguments are used + * by this function: 'dnsserver_location' is the complete path to the + * dnsserver execuatable; 'path' is the absolute path used by the + * Unix socket. + */ +int +start_dnsserver(const char* dnsserver_location, const char* path) +{ + int ret; + + assert(dnsserver_location != NULL); + assert(path != NULL); + + unix_socket_loc = safestrdup(path); + + if ((dnsserver_process = fork()) == 0) { + /* Child process */ + chdir("/"); + umask(077); + + close(0); + close(1); + close(2); + + /* Start the "dnsserver" program */ + ret = execl(dnsserver_location, + dnsserver_location, + path, + NULL); + + if (ret < 0) + return -ENOEXEC; + } + + /* Parent process */ + return 0; +} + +/* + * Stop the dnsserver process. + */ +int +stop_dnsserver(void) +{ + kill(dnsserver_process, SIGTERM); + kill(dnsserver_process, SIGKILL); + unlink(unix_socket_loc); + + return 0; +} + +/* + * Returns a socket connected to the "dnsserver" + */ +int +dns_connect(void) +{ + int dns; + struct sockaddr_un addr; + + dns = socket(AF_LOCAL, SOCK_STREAM, 0); + if (dns < 0) + return -EIO; + + memset(&addr, 0, sizeof(addr)); + addr.sun_family = AF_LOCAL; + strcpy(addr.sun_path, unix_socket_loc); + + if (connect(dns, (struct sockaddr *)&addr, sizeof(addr)) < 0) + return -EIO; + else + return dns; +} + +/* + * Closes the connection to the "dnsserver" + */ +void +dns_disconnect(int dns) +{ + assert(dns >= 0); + + safe_write(dns, "$shutdown\n", 10); + close(dns); +} + +/* + * Takes a dotted-decimal IP address and returns the host name in the + * buffer supplied by the caller. + * + * Returns: 0 if the buffer is filled correctly, or + * -1 if there was an error + */ +int +dns_gethostbyaddr(int dns, const char* ipaddr, char** hostname, + size_t hostlen) +{ + char* buffer; + ssize_t len; + char *ptr; + + assert(dns >= 0); + assert(ipaddr != NULL); + assert(hostname != NULL); + assert(hostlen > 0); + + write_message(dns, "%s\n", ipaddr); + len = readline(dns, &buffer); + if (len < 0) + return len; + chomp(buffer, len); + + if (strncmp(buffer, "$fail", 5) == 0) { + /* There was a problem. */ + safefree(buffer); + return -ENOMSG; + } + + ptr = strchr(buffer, ' '); + ptr++; + + strlcpy(*hostname, ptr, hostlen); + + safefree(buffer); + return 0; +} + +/* + * Takes a host name and returns an array of IP addresses. The caller + * is responsible for freeing the 'addresses' memory block. + */ +int +dns_getaddrbyname(int dns, const char* name, struct in_addr** addresses) +{ + char* buffer; + ssize_t len; + char *ptr; + + assert(dns >= 0); + assert(name != NULL); + assert(addresses != NULL); + + write_message(dns, "%s\n", name); + len = readline(dns, &buffer); + if (len < 0) + return len; + chomp(buffer, len); + + if (strncmp(buffer, "$fail", 5) == 0) { + safefree(buffer); + return -ENOMSG; + } + + ptr = strchr(buffer + 6, ' '); + if (ptr) + *ptr = '\0'; + + *addresses = safemalloc(sizeof(struct in_addr)); + if (!*addresses) { + safefree(buffer); + return -ENOMEM; + } + + inet_aton(buffer + 6, *addresses); + + safefree(buffer); + return 0; +} diff --git a/src/dnsclient.h b/src/dnsclient.h new file mode 100644 index 0000000..32bad58 --- /dev/null +++ b/src/dnsclient.h @@ -0,0 +1,32 @@ +/* $Id: dnsclient.h,v 1.1 2002-05-23 04:40:06 rjkaes Exp $ + * + * See 'dnsclient.c' for a detailed description. + * + * Copyright (C) 2002 Robert James Kaes (rjkaes@flarenet.com) + * + * This program 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. + * + * This program 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. + */ + +#ifndef TINYPROXY_DNSCLIENT_H +#define TINYPROXY_DNSCLIENT_H + +extern int start_dnsserver(const char* dnsserver_location, const char* path); +extern int stop_dnsserver(void); + +extern int dns_connect(void); +extern void dns_disconnect(int dns); + +extern int dns_gethostbyaddr(int dns, const char* ipaddr, char** hostname, + size_t hostlen); +extern int dns_getaddrbyname(int dns, const char* name, + struct in_addr** addresses); + +#endif |