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Diffstat (limited to '')
| -rw-r--r-- | libevent/sample/dns-example.c | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/libevent/sample/dns-example.c b/libevent/sample/dns-example.c new file mode 100644 index 0000000..2d07c38 --- /dev/null +++ b/libevent/sample/dns-example.c @@ -0,0 +1,264 @@ +/* + 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 <event2/event-config.h> + +/* Compatibility for possible missing IPv6 declarations */ +#include "../ipv6-internal.h" + +#include <sys/types.h> + +#ifdef EVENT__HAVE_UNISTD_H +#include <unistd.h> +#endif + +#ifdef _WIN32 +#include <winsock2.h> +#include <ws2tcpip.h> +#include <getopt.h> +#else +#include <sys/socket.h> +#include <netinet/in.h> +#include <arpa/inet.h> +#endif + +#include <event2/event.h> +#include <event2/dns.h> +#include <event2/dns_struct.h> +#include <event2/util.h> + +#ifdef EVENT__HAVE_NETINET_IN6_H +#include <netinet/in6.h> +#endif + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#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; + struct evutil_addrinfo *first_ai = ai; + + 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); + } + } + + if (first_ai) + evutil_freeaddrinfo(first_ai); +} + +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; + int 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:g")) != -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) { + fprintf(stderr, "Couldn't configure nameservers\n"); + 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); + evdns_base_free(evdns_base, 1); + event_base_free(event_base); + return 0; +} + |