asyncns-test.c

An example program

00001 /* $Id: asyncns-test.c 27 2007-02-16 13:51:03Z lennart $ */
00002 
00003 /***
00004   This file is part of libasyncns.
00005  
00006   libasyncns is free software; you can redistribute it and/or modify
00007   it under the terms of the GNU Lesser General Public License as
00008   published by the Free Software Foundation; either version 2 of the
00009   License, or (at your option) any later version.
00010  
00011   libasyncns is distributed in the hope that it will be useful, but
00012   WITHOUT ANY WARRANTY; without even the implied warranty of
00013   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
00014   General Public License for more details.
00015  
00016   You should have received a copy of the GNU Lesser General Public
00017   License along with libasyncns; if not, write to the Free Software
00018   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
00019   USA.
00020 ***/
00021 
00022 #if HAVE_CONFIG_H
00023 #include <config.h>
00024 #endif
00025 
00026 #include <string.h>
00027 #include <sys/types.h>
00028 #include <sys/socket.h>
00029 #include <arpa/inet.h>
00030 #include <stdio.h>
00031 #include <netinet/in.h>
00032 #include <arpa/nameser.h>
00033 #include <resolv.h>
00034 #include <assert.h>
00035 
00036 #include "asyncns.h"
00037 
00038 int main(int argc, char *argv[]) {
00039     asyncns_t* asyncns = NULL;
00040     asyncns_query_t *q1, *q2, *q3;
00041     int r = 1, ret;
00042     struct addrinfo *ai, hints;
00043     struct sockaddr_in sa;
00044     char host[NI_MAXHOST] = "", serv[NI_MAXSERV] = "";
00045     unsigned char *srv;
00046 
00047     if (!(asyncns = asyncns_new(10))) {
00048         fprintf(stderr, "asyncns_new() failed\n");
00049         goto fail;
00050     }
00051 
00052     /* Make a name -> address query */
00053     memset(&hints, 0, sizeof(hints));
00054     hints.ai_family = PF_UNSPEC;
00055     hints.ai_socktype = SOCK_STREAM;
00056 
00057     q1 = asyncns_getaddrinfo(asyncns, argc >= 2 ? argv[1] : "www.heise.de", NULL, &hints);
00058 
00059     /* Make an address -> name query */
00060     memset(&sa, 0, sizeof(sa));
00061     sa.sin_family = AF_INET;
00062     sa.sin_addr.s_addr = inet_addr(argc >= 3 ? argv[2] : "193.99.144.71");
00063     sa.sin_port = htons(80);
00064     
00065     q2 = asyncns_getnameinfo(asyncns, (struct sockaddr*) &sa, sizeof(sa), 0, 1, 1); 
00066 
00067     /* Make a res_query() call */
00068     q3 = asyncns_res_query(asyncns, "_xmpp-client._tcp.gmail.com", C_IN, T_SRV); 
00069 
00070     /* Wait until the three queries are completed */
00071     while (!asyncns_isdone(asyncns, q1) 
00072            || !asyncns_isdone(asyncns, q2)
00073            || !asyncns_isdone(asyncns, q3)) {
00074         if (asyncns_wait(asyncns, 1) < 0)
00075             goto fail;
00076     }
00077 
00078     /* Interpret the result of the name -> addr query */
00079     if ((ret = asyncns_getaddrinfo_done(asyncns, q1, &ai)))
00080         fprintf(stderr, "error: %s %i\n", gai_strerror(ret), ret);
00081     else {
00082         struct addrinfo *i;
00083 
00084         for (i = ai; i; i = i->ai_next) {
00085             char t[256];
00086             const char *p = NULL;
00087 
00088             if (i->ai_family == PF_INET) 
00089                 p = inet_ntop(AF_INET, &((struct sockaddr_in*) i->ai_addr)->sin_addr, t, sizeof(t));
00090             else if (i->ai_family == PF_INET6)
00091                 p = inet_ntop(AF_INET6, &((struct sockaddr_in6*) i->ai_addr)->sin6_addr, t, sizeof(t));
00092                           
00093             printf("%s\n", p);
00094         }
00095 
00096         asyncns_freeaddrinfo(ai);
00097     }
00098 
00099     /* Interpret the result of the addr -> name query */
00100     if ((ret = asyncns_getnameinfo_done(asyncns, q2, host, sizeof(host), serv, sizeof(serv))))
00101         fprintf(stderr, "error: %s %i\n", gai_strerror(ret), ret);
00102     else
00103         printf("%s -- %s\n", host, serv);
00104 
00105     /* Interpret the result of the SRV lookup */
00106     if ((ret = asyncns_res_done(asyncns, q3, &srv)) < 0) {
00107         fprintf(stderr, "error: %s %i\n", strerror(ret), ret);
00108     } else if (ret == 0) { 
00109         fprintf(stderr, "No reply for SRV lookup\n");
00110     } else {
00111         int qdcount;
00112         int ancount;
00113         int len;
00114         const unsigned char *pos = srv + sizeof(HEADER);
00115         unsigned char *end = srv + ret;
00116         HEADER *head = (HEADER *)srv;
00117         char name[256];
00118 
00119         qdcount = ntohs(head->qdcount);
00120         ancount = ntohs(head->ancount);
00121 
00122         printf("%d answers for srv lookup:\n", ancount);
00123 
00124         /* Ignore the questions */
00125         while (qdcount-- > 0 && (len = dn_expand(srv, end, pos, name, 255)) >= 0) {
00126             assert(len >= 0);
00127             pos += len + QFIXEDSZ;
00128         }
00129 
00130         /* Parse the answers */
00131         while (ancount-- > 0 && (len = dn_expand(srv, end, pos, name, 255)) >= 0) {
00132             /* Ignore the initial string */
00133             uint16_t pref, weight, port;
00134             assert(len >= 0);
00135             pos += len;
00136             /* Ignore type, ttl, class and dlen */
00137             pos += 10;
00138         
00139             GETSHORT(pref, pos);
00140             GETSHORT(weight, pos);
00141             GETSHORT(port, pos);
00142             len = dn_expand(srv, end, pos, name, 255); 
00143             printf("\tpreference: %2d weight: %2d port: %d host: %s\n",
00144                    pref, weight, port, name);
00145 
00146             pos += len;
00147         }
00148     }
00149     
00150     r = 0;
00151 
00152 fail:
00153 
00154     if (asyncns)
00155         asyncns_free(asyncns);
00156     
00157     return r;
00158 }

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