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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Web crawler based on curl and libxml2.
* Copyright (C) 2018 - 2019 Jeroen Ooms <jeroenooms@gmail.com>
* License: MIT
*
* To compile:
* gcc crawler.c $(pkg-config --cflags --libs libxml-2.0 libcurl)
*
*/
/* <DESC>
* Web crawler based on curl and libxml2 to stress-test curl with
* hundreds of concurrent connections to various servers.
* </DESC>
*/
/* Parameters */
int max_con = 200;
int max_total = 20000;
int max_requests = 500;
int max_link_per_page = 5;
int follow_relative_links = 0;
char *start_page = "https://www.reuters.com";
#include <libxml/HTMLparser.h>
#include <libxml/xpath.h>
#include <libxml/uri.h>
#include <curl/curl.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <signal.h>
int pending_interrupt = 0;
void sighandler(int dummy)
{
pending_interrupt = 1;
}
/* resizable buffer */
typedef struct {
char *buf;
size_t size;
} memory;
size_t grow_buffer(void *contents, size_t sz, size_t nmemb, void *ctx)
{
size_t realsize = sz * nmemb;
memory *mem = (memory*) ctx;
char *ptr = realloc(mem->buf, mem->size + realsize);
if(!ptr) {
/* out of memory */
printf("not enough memory (realloc returned NULL)\n");
return 0;
}
mem->buf = ptr;
memcpy(&(mem->buf[mem->size]), contents, realsize);
mem->size += realsize;
return realsize;
}
CURL *make_handle(char *url)
{
CURL *handle = curl_easy_init();
/* Important: use HTTP2 over HTTPS */
curl_easy_setopt(handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
curl_easy_setopt(handle, CURLOPT_URL, url);
/* buffer body */
memory *mem = malloc(sizeof(memory));
mem->size = 0;
mem->buf = malloc(1);
curl_easy_setopt(handle, CURLOPT_WRITEFUNCTION, grow_buffer);
curl_easy_setopt(handle, CURLOPT_WRITEDATA, mem);
curl_easy_setopt(handle, CURLOPT_PRIVATE, mem);
/* For completeness */
curl_easy_setopt(handle, CURLOPT_ACCEPT_ENCODING, "");
curl_easy_setopt(handle, CURLOPT_TIMEOUT, 5L);
curl_easy_setopt(handle, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(handle, CURLOPT_MAXREDIRS, 10L);
curl_easy_setopt(handle, CURLOPT_CONNECTTIMEOUT, 2L);
curl_easy_setopt(handle, CURLOPT_COOKIEFILE, "");
curl_easy_setopt(handle, CURLOPT_FILETIME, 1L);
curl_easy_setopt(handle, CURLOPT_USERAGENT, "mini crawler");
curl_easy_setopt(handle, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
curl_easy_setopt(handle, CURLOPT_UNRESTRICTED_AUTH, 1L);
curl_easy_setopt(handle, CURLOPT_PROXYAUTH, CURLAUTH_ANY);
curl_easy_setopt(handle, CURLOPT_EXPECT_100_TIMEOUT_MS, 0L);
return handle;
}
/* HREF finder implemented in libxml2 but could be any HTML parser */
size_t follow_links(CURLM *multi_handle, memory *mem, char *url)
{
int opts = HTML_PARSE_NOBLANKS | HTML_PARSE_NOERROR | \
HTML_PARSE_NOWARNING | HTML_PARSE_NONET;
htmlDocPtr doc = htmlReadMemory(mem->buf, mem->size, url, NULL, opts);
if(!doc)
return 0;
xmlChar *xpath = (xmlChar*) "//a/@href";
xmlXPathContextPtr context = xmlXPathNewContext(doc);
xmlXPathObjectPtr result = xmlXPathEvalExpression(xpath, context);
xmlXPathFreeContext(context);
if(!result)
return 0;
xmlNodeSetPtr nodeset = result->nodesetval;
if(xmlXPathNodeSetIsEmpty(nodeset)) {
xmlXPathFreeObject(result);
return 0;
}
size_t count = 0;
for(int i = 0; i < nodeset->nodeNr; i++) {
double r = rand();
int x = r * nodeset->nodeNr / RAND_MAX;
const xmlNode *node = nodeset->nodeTab[x]->xmlChildrenNode;
xmlChar *href = xmlNodeListGetString(doc, node, 1);
if(follow_relative_links) {
xmlChar *orig = href;
href = xmlBuildURI(href, (xmlChar *) url);
xmlFree(orig);
}
char *link = (char *) href;
if(!link || strlen(link) < 20)
continue;
if(!strncmp(link, "http://", 7) || !strncmp(link, "https://", 8)) {
curl_multi_add_handle(multi_handle, make_handle(link));
if(count++ == max_link_per_page)
break;
}
xmlFree(link);
}
xmlXPathFreeObject(result);
return count;
}
int is_html(char *ctype)
{
return ctype != NULL && strlen(ctype) > 10 && strstr(ctype, "text/html");
}
int main(void)
{
signal(SIGINT, sighandler);
LIBXML_TEST_VERSION;
curl_global_init(CURL_GLOBAL_DEFAULT);
CURLM *multi_handle = curl_multi_init();
curl_multi_setopt(multi_handle, CURLMOPT_MAX_TOTAL_CONNECTIONS, max_con);
curl_multi_setopt(multi_handle, CURLMOPT_MAX_HOST_CONNECTIONS, 6L);
/* enables http/2 if available */
#ifdef CURLPIPE_MULTIPLEX
curl_multi_setopt(multi_handle, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
#endif
/* sets html start page */
curl_multi_add_handle(multi_handle, make_handle(start_page));
int msgs_left;
int pending = 0;
int complete = 0;
int still_running = 1;
while(still_running && !pending_interrupt) {
int numfds;
curl_multi_wait(multi_handle, NULL, 0, 1000, &numfds);
curl_multi_perform(multi_handle, &still_running);
/* See how the transfers went */
CURLMsg *m = NULL;
while((m = curl_multi_info_read(multi_handle, &msgs_left))) {
if(m->msg == CURLMSG_DONE) {
CURL *handle = m->easy_handle;
char *url;
memory *mem;
curl_easy_getinfo(handle, CURLINFO_PRIVATE, &mem);
curl_easy_getinfo(handle, CURLINFO_EFFECTIVE_URL, &url);
if(m->data.result == CURLE_OK) {
long res_status;
curl_easy_getinfo(handle, CURLINFO_RESPONSE_CODE, &res_status);
if(res_status == 200) {
char *ctype;
curl_easy_getinfo(handle, CURLINFO_CONTENT_TYPE, &ctype);
printf("[%d] HTTP 200 (%s): %s\n", complete, ctype, url);
if(is_html(ctype) && mem->size > 100) {
if(pending < max_requests && (complete + pending) < max_total) {
pending += follow_links(multi_handle, mem, url);
still_running = 1;
}
}
}
else {
printf("[%d] HTTP %d: %s\n", complete, (int) res_status, url);
}
}
else {
printf("[%d] Connection failure: %s\n", complete, url);
}
curl_multi_remove_handle(multi_handle, handle);
curl_easy_cleanup(handle);
free(mem->buf);
free(mem);
complete++;
pending--;
}
}
}
curl_multi_cleanup(multi_handle);
curl_global_cleanup();
return 0;
}
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