/* $NetBSD: dns-example.c,v 1.1.1.2 2017/01/31 21:14:53 christos Exp $ */ /* This example code shows how to use the high-level, low-level, and server-level interfaces of evdns. XXX It's pretty ugly and should probably be cleaned up. */ #include /* Compatibility for possible missing IPv6 declarations */ #include "../ipv6-internal.h" #include #ifdef EVENT__HAVE_UNISTD_H #include #endif #ifdef _WIN32 #include #include #include #else #include #include #include #endif #include #include #include #include #ifdef EVENT__HAVE_NETINET_IN6_H #include #endif #include #include #include #define u32 ev_uint32_t #define u8 ev_uint8_t static const char * debug_ntoa(u32 address) { static char buf[32]; u32 a = ntohl(address); evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d", (int)(u8)((a>>24)&0xff), (int)(u8)((a>>16)&0xff), (int)(u8)((a>>8 )&0xff), (int)(u8)((a )&0xff)); return buf; } static void main_callback(int result, char type, int count, int ttl, void *addrs, void *orig) { char *n = (char*)orig; int i; for (i = 0; i < count; ++i) { if (type == DNS_IPv4_A) { printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i])); } else if (type == DNS_PTR) { printf("%s: %s\n", n, ((char**)addrs)[i]); } } if (!count) { printf("%s: No answer (%d)\n", n, result); } fflush(stdout); } static void gai_callback(int err, struct evutil_addrinfo *ai, void *arg) { const char *name = arg; int i; if (err) { printf("%s: %s\n", name, evutil_gai_strerror(err)); } if (ai && ai->ai_canonname) printf(" %s ==> %s\n", name, ai->ai_canonname); for (i=0; ai; ai = ai->ai_next, ++i) { char buf[128]; if (ai->ai_family == PF_INET) { struct sockaddr_in *sin = (struct sockaddr_in*)ai->ai_addr; evutil_inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)); printf("[%d] %s: %s\n",i,name,buf); } else { struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)ai->ai_addr; evutil_inet_ntop(AF_INET6, &sin6->sin6_addr, buf, sizeof(buf)); printf("[%d] %s: %s\n",i,name,buf); } } } static void evdns_server_callback(struct evdns_server_request *req, void *data) { int i, r; (void)data; /* dummy; give 192.168.11.11 as an answer for all A questions, * give foo.bar.example.com as an answer for all PTR questions. */ for (i = 0; i < req->nquestions; ++i) { u32 ans = htonl(0xc0a80b0bUL); if (req->questions[i]->type == EVDNS_TYPE_A && req->questions[i]->dns_question_class == EVDNS_CLASS_INET) { printf(" -- replying for %s (A)\n", req->questions[i]->name); r = evdns_server_request_add_a_reply(req, req->questions[i]->name, 1, &ans, 10); if (r<0) printf("eeep, didn't work.\n"); } else if (req->questions[i]->type == EVDNS_TYPE_PTR && req->questions[i]->dns_question_class == EVDNS_CLASS_INET) { printf(" -- replying for %s (PTR)\n", req->questions[i]->name); r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name, "foo.bar.example.com", 10); if (r<0) printf("ugh, no luck"); } else { printf(" -- skipping %s [%d %d]\n", req->questions[i]->name, req->questions[i]->type, req->questions[i]->dns_question_class); } } r = evdns_server_request_respond(req, 0); if (r<0) printf("eeek, couldn't send reply.\n"); } static int verbose = 0; static void logfn(int is_warn, const char *msg) { if (!is_warn && !verbose) return; fprintf(stderr, "%s: %s\n", is_warn?"WARN":"INFO", msg); } int main(int c, char **v) { struct options { int reverse; int use_getaddrinfo; int servertest; const char *resolv_conf; const char *ns; }; struct options o; char opt; struct event_base *event_base = NULL; struct evdns_base *evdns_base = NULL; memset(&o, 0, sizeof(o)); if (c < 2) { fprintf(stderr, "syntax: %s [-x] [-v] [-c resolv.conf] [-s ns] hostname\n", v[0]); fprintf(stderr, "syntax: %s [-T]\n", v[0]); return 1; } while ((opt = getopt(c, v, "xvc:Ts:")) != -1) { switch (opt) { case 'x': o.reverse = 1; break; case 'v': ++verbose; break; case 'g': o.use_getaddrinfo = 1; break; case 'T': o.servertest = 1; break; case 'c': o.resolv_conf = optarg; break; case 's': o.ns = optarg; break; default : fprintf(stderr, "Unknown option %c\n", opt); break; } } #ifdef _WIN32 { WSADATA WSAData; WSAStartup(0x101, &WSAData); } #endif event_base = event_base_new(); evdns_base = evdns_base_new(event_base, EVDNS_BASE_DISABLE_WHEN_INACTIVE); evdns_set_log_fn(logfn); if (o.servertest) { evutil_socket_t sock; struct sockaddr_in my_addr; sock = socket(PF_INET, SOCK_DGRAM, 0); if (sock == -1) { perror("socket"); exit(1); } evutil_make_socket_nonblocking(sock); my_addr.sin_family = AF_INET; my_addr.sin_port = htons(10053); my_addr.sin_addr.s_addr = INADDR_ANY; if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) { perror("bind"); exit(1); } evdns_add_server_port_with_base(event_base, sock, 0, evdns_server_callback, NULL); } if (optind < c) { int res; #ifdef _WIN32 if (o.resolv_conf == NULL && !o.ns) res = evdns_base_config_windows_nameservers(evdns_base); else #endif if (o.ns) res = evdns_base_nameserver_ip_add(evdns_base, o.ns); else res = evdns_base_resolv_conf_parse(evdns_base, DNS_OPTION_NAMESERVERS, o.resolv_conf); if (res < 0) { fprintf(stderr, "Couldn't configure nameservers"); return 1; } } printf("EVUTIL_AI_CANONNAME in example = %d\n", EVUTIL_AI_CANONNAME); for (; optind < c; ++optind) { if (o.reverse) { struct in_addr addr; if (evutil_inet_pton(AF_INET, v[optind], &addr)!=1) { fprintf(stderr, "Skipping non-IP %s\n", v[optind]); continue; } fprintf(stderr, "resolving %s...\n",v[optind]); evdns_base_resolve_reverse(evdns_base, &addr, 0, main_callback, v[optind]); } else if (o.use_getaddrinfo) { struct evutil_addrinfo hints; memset(&hints, 0, sizeof(hints)); hints.ai_family = PF_UNSPEC; hints.ai_protocol = IPPROTO_TCP; hints.ai_flags = EVUTIL_AI_CANONNAME; fprintf(stderr, "resolving (fwd) %s...\n",v[optind]); evdns_getaddrinfo(evdns_base, v[optind], NULL, &hints, gai_callback, v[optind]); } else { fprintf(stderr, "resolving (fwd) %s...\n",v[optind]); evdns_base_resolve_ipv4(evdns_base, v[optind], 0, main_callback, v[optind]); } } fflush(stdout); event_base_dispatch(event_base); return 0; }