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/*
* (C) 2013 by Christian Hesse <mail@eworm.de>
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*
* This is an example code skeleton provided by vim-skeleton.
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <time.h>
#include <avahi-client/client.h>
#include <avahi-client/lookup.h>
#include <avahi-common/simple-watch.h>
#include <avahi-common/malloc.h>
#include <avahi-common/error.h>
#include <curl/curl.h>
#include <microhttpd.h>
#define PAGE307 "<html><head><title>307 temporary redirect</title>" \
"</head><body>307 temporary redirect: " \
"<a href=\"%s\">%s</a></body></html>"
#define PAGE404 "<html><head><title>404 Not Found</title>" \
"</head><body>404 Not Found: %s</body></html>"
#define PORT 7077
#define SERVICE "_pacserve._tcp"
#define BADTIME 60 * 10
/* hosts */
struct hosts {
/* host name */
char * host;
/* http port */
uint16_t port;
/* unix timestamp of last bad request */
__time_t bad;
/* true if host is offline */
uint8_t offline;
/* pointer to next struct element */
struct hosts * next;
};
/* global variables */
struct hosts * hosts = NULL;
static AvahiSimplePoll *simple_poll = NULL;
/*** resolve_callback_new ***
* Called whenever a service has been resolved successfully or timed out */
static void resolve_callback_new(AvahiServiceResolver *r, AVAHI_GCC_UNUSED AvahiIfIndex interface, AVAHI_GCC_UNUSED AvahiProtocol protocol,
AvahiResolverEvent event, const char *name, const char *type, const char *domain, const char *host, const AvahiAddress *address,
AVAHI_GCC_UNUSED uint16_t port, AVAHI_GCC_UNUSED AvahiStringList *txt, AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
AVAHI_GCC_UNUSED void* userdata) {
struct hosts * tmphosts = hosts;
assert(r);
switch (event) {
case AVAHI_RESOLVER_FAILURE:
fprintf(stderr, "(Resolver) Failed to resolve service '%s' of type '%s' in domain '%s': %s\n",
name, type, domain, avahi_strerror(avahi_client_errno(avahi_service_resolver_get_client(r))));
break;
case AVAHI_RESOLVER_FOUND: {
while (tmphosts->host != NULL) {
if (strcmp(tmphosts->host, host) == 0) {
# if defined DEBUG
printf("Host is already in the list: %s\n", host);
# endif
tmphosts->offline = 0;
goto out;
}
tmphosts = tmphosts->next;
}
printf("Adding host: %s, port %d\n", host, port);
tmphosts->host = strdup(host);
tmphosts->port = port;
tmphosts->bad = 0;
tmphosts->offline = 0;
tmphosts->next = realloc(tmphosts->next, sizeof(struct hosts));
tmphosts = tmphosts->next;
tmphosts->host = NULL;
tmphosts->next = NULL;
break;
}
}
out:
avahi_service_resolver_free(r);
}
/*** resolve_callback_remove ***
* Called whenever a service has been resolved successfully or timed out */
static void resolve_callback_remove(AvahiServiceResolver *r, AVAHI_GCC_UNUSED AvahiIfIndex interface, AVAHI_GCC_UNUSED AvahiProtocol protocol,
AvahiResolverEvent event, const char *name, const char *type, const char *domain, const char *host, const AvahiAddress *address,
AVAHI_GCC_UNUSED uint16_t port, AVAHI_GCC_UNUSED AvahiStringList *txt, AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
AVAHI_GCC_UNUSED void* userdata) {
struct hosts * tmphosts = hosts;
assert(r);
switch (event) {
case AVAHI_RESOLVER_FAILURE:
fprintf(stderr, "(Resolver) Failed to resolve service '%s' of type '%s' in domain '%s': %s\n",
name, type, domain, avahi_strerror(avahi_client_errno(avahi_service_resolver_get_client(r))));
break;
case AVAHI_RESOLVER_FOUND: {
while (tmphosts->host != NULL) {
if (strcmp(tmphosts->host, host) == 0) {
printf("Marking host offline: %s\n", host);
tmphosts->offline = 1;
goto out;
}
tmphosts = tmphosts->next;
}
break;
}
}
out:
avahi_service_resolver_free(r);
}
/*** browse_callback ***
* Called whenever a new services becomes available on the LAN or is removed from the LAN */
static void browse_callback(AvahiServiceBrowser *b, AvahiIfIndex interface, AvahiProtocol protocol, AvahiBrowserEvent event, const char *name,
const char *type, const char *domain, AVAHI_GCC_UNUSED AvahiLookupResultFlags flags, void* userdata) {
AvahiClient *c = userdata;
assert(b);
switch (event) {
case AVAHI_BROWSER_FAILURE:
fprintf(stderr, "(Browser) %s\n", avahi_strerror(avahi_client_errno(avahi_service_browser_get_client(b))));
avahi_simple_poll_quit(simple_poll);
return;
case AVAHI_BROWSER_NEW:
# if defined DEBUG
fprintf(stderr, "(Browser) NEW: service '%s' of type '%s' in domain '%s'\n", name, type, domain);
# endif
/* We ignore the returned resolver object. In the callback
* function we free it. If the server is terminated before
* the callback function is called the server will free
* the resolver for us. */
if (avahi_service_resolver_new(c, interface, protocol, name, type, domain, AVAHI_PROTO_UNSPEC, 0, resolve_callback_new, c) == NULL)
fprintf(stderr, "Failed to resolve service '%s': %s\n", name, avahi_strerror(avahi_client_errno(c)));
break;
case AVAHI_BROWSER_REMOVE:
# if defined DEBUG
fprintf(stderr, "(Browser) REMOVE: service '%s' of type '%s' in domain '%s'\n", name, type, domain);
# endif
if (avahi_service_resolver_new(c, interface, protocol, name, type, domain, AVAHI_PROTO_UNSPEC, 0, resolve_callback_remove, c) == NULL)
fprintf(stderr, "Failed to resolve service '%s': %s\n", name, avahi_strerror(avahi_client_errno(c)));
break;
case AVAHI_BROWSER_ALL_FOR_NOW:
case AVAHI_BROWSER_CACHE_EXHAUSTED:
break;
}
}
/*** client_callback ***/
static void client_callback(AvahiClient *c, AvahiClientState state, AVAHI_GCC_UNUSED void * userdata) {
assert(c);
if (state == AVAHI_CLIENT_FAILURE) {
fprintf(stderr, "Server connection failure: %s\n", avahi_strerror(avahi_client_errno(c)));
avahi_simple_poll_quit(simple_poll);
}
}
/*** get_http_code ***/
int get_http_code(const char * host, const uint16_t port, const char * url) {
CURL *curl;
CURLcode res;
unsigned int http_code;
curl_global_init(CURL_GLOBAL_ALL);
if ((curl = curl_easy_init()) != NULL) {
curl_easy_setopt(curl, CURLOPT_URL, url);
/* example.com is redirected, so we tell libcurl to follow redirection */
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
/* set user agent */
curl_easy_setopt(curl, CURLOPT_USERAGENT, "pacredir/" VERSION);
/* do not receive body */
curl_easy_setopt(curl, CURLOPT_NOBODY, 1);
/* set connection timeout to 2 seconds
* if the host needs longer we do not want to use it anyway ;) */
curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 2);
/* get it! */
if (curl_easy_perform(curl) != CURLE_OK) {
fprintf(stderr, "Could not connect to server %s on port %d.\n", host, port);
return -1;
}
if ((res = curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &http_code)) != CURLE_OK) {
fprintf(stderr, "curl_easy_getinfo() failed: %s\n", curl_easy_strerror(res));
return -1;
}
/* always cleanup */
curl_easy_cleanup(curl);
}
/* we're done with libcurl, so clean it up */
curl_global_cleanup();
return http_code;
}
/*** ahc_echo ***
* called whenever a http request is received */
static int ahc_echo(void * cls, struct MHD_Connection * connection, const char * uri, const char * method,
const char * version, const char * upload_data, size_t * upload_data_size, void ** ptr) {
static int dummy;
struct MHD_Response * response;
int ret;
struct hosts * tmphosts = hosts;
char * url = NULL, * page;
const char * basename;
int http_code = 0;
struct timeval tv;
/* we want to filename, not the path */
basename = uri;
while (strstr(basename, "/") != NULL)
basename = strstr(basename, "/") + 1;
if (strcmp(method, "GET") != 0)
return MHD_NO; /* unexpected method */
if (&dummy != *ptr) {
/* The first time only the headers are valid,
* do not respond in the first round... */
*ptr = &dummy;
return MHD_YES;
}
if (*upload_data_size != 0)
return MHD_NO; /* upload data in a GET!? */
/* clear context pointer */
*ptr = NULL;
/* do not process db requests */
/* TODO: do some timestamp magic to find suitable db files */
if (strcmp(basename + strlen(basename) - 3, ".db") == 0) {
# if defined DEBUG
printf("Not precessing db file request for %s\n", basename);
# endif
} else {
/* try to find a server */
while (tmphosts->host != NULL) {
gettimeofday(&tv, NULL);
/* skip host if offline or had a bad request within last BADTIME seconds */
if (tmphosts->offline == 1 || tmphosts->bad + BADTIME > tv.tv_sec) {
tmphosts = tmphosts->next;
continue;
}
url = malloc(10 + strlen(tmphosts->host) + 5 + strlen(basename));
sprintf(url, "http://%s:%d/%s", tmphosts->host, tmphosts->port, basename);
printf("Trying %s\n", url);
if ((http_code = get_http_code(tmphosts->host, tmphosts->port, url)) == MHD_HTTP_OK)
break;
else if (http_code == -1)
tmphosts->bad = tv.tv_sec;
tmphosts = tmphosts->next;
}
}
/* give response */
if (http_code == MHD_HTTP_OK) {
printf("Redirecting to %s\n", url);
page = malloc(strlen(PAGE307) + strlen(url) + strlen(basename) + 1);
sprintf(page, PAGE307, url, basename);
response = MHD_create_response_from_data(strlen(url), (void*) url, MHD_NO, MHD_NO);
ret = MHD_add_response_header(response, "Location", url);
ret = MHD_queue_response(connection, MHD_HTTP_TEMPORARY_REDIRECT, response);
} else {
printf("File %s not found, giving up.\n", basename);
page = malloc(strlen(PAGE404) + strlen(basename) + 1);
sprintf(page, PAGE404, basename);
response = MHD_create_response_from_data(strlen(page), (void*) page, MHD_NO, MHD_NO);
ret = MHD_queue_response(connection, MHD_HTTP_NOT_FOUND, response);
}
MHD_destroy_response(response);
free(page);
if (url != NULL)
free(url);
return ret;
}
/*** sigterm_callback ***/
void sigterm_callback(int signal) {
avahi_simple_poll_quit(simple_poll);
}
/*** sighup_callback ***/
void sighup_callback(int signal) {
struct hosts * tmphosts = hosts;
printf("Received SIGHUP, marking all hosts offline.\n");
while (tmphosts->host != NULL) {
tmphosts->offline = 1;
tmphosts = tmphosts->next;
}
}
/*** main ***/
int main(int argc, char ** argv) {
AvahiClient *client = NULL;
AvahiServiceBrowser *sb = NULL;
int error;
int ret = 1;
struct MHD_Daemon * mhd;
struct hosts * tmphosts;
printf("Starting pacredir/" VERSION "\n");
/* allocate first struct element as dummy */
hosts = malloc(sizeof(struct hosts));
hosts->host = NULL;
hosts->port = 0;
hosts->bad = 0;
hosts->offline = 0;
hosts->next = NULL;
/* allocate main loop object */
if (!(simple_poll = avahi_simple_poll_new())) {
fprintf(stderr, "Failed to create simple poll object.\n");
goto fail;
}
/* allocate a new client */
client = avahi_client_new(avahi_simple_poll_get(simple_poll), 0, client_callback, NULL, &error);
/* check wether creating the client object succeeded */
if (!client) {
fprintf(stderr, "Failed to create client: %s\n", avahi_strerror(error));
goto fail;
}
/* create the service browser */
if (!(sb = avahi_service_browser_new(client, AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC, SERVICE, NULL, 0, browse_callback, client))) {
fprintf(stderr, "Failed to create service browser: %s\n", avahi_strerror(avahi_client_errno(client)));
goto fail;
}
if ((mhd = MHD_start_daemon(MHD_USE_THREAD_PER_CONNECTION, PORT, NULL, NULL, &ahc_echo, NULL, MHD_OPTION_END)) == NULL) {
fprintf(stderr, "Could not start daemon on port %d.\n", PORT);
return EXIT_FAILURE;
}
/* register signal callbacks */
signal(SIGTERM, sigterm_callback);
signal(SIGHUP, sighup_callback);
/* run the main loop */
avahi_simple_poll_loop(simple_poll);
MHD_stop_daemon(mhd);
ret = EXIT_SUCCESS;
fail:
/* Cleanup things */
while(hosts->host != NULL) {
free(hosts->host);
tmphosts = hosts->next;
free(hosts);
hosts = tmphosts;
}
if (sb)
avahi_service_browser_free(sb);
if (client)
avahi_client_free(client);
if (simple_poll)
avahi_simple_poll_free(simple_poll);
return ret;
}
// vim: set syntax=c:
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