curl を使って HTTP Get

sample_curl.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "curl/curl.h"

typedef struct {
	char *m;
	size_t size;
} Memory;

size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata);

int main(int argc, char **argv)
{
	CURL *curl;
	CURLcode ret;
	Memory response_body;

	curl_global_init(CURL_GLOBAL_ALL);

	curl = curl_easy_init();
	if (curl == NULL) {
		fprintf(stderr, "Error: curl_easy_init() failed\n");
		return 1;
	}

	response_body.m = (char *)malloc(1);
	response_body.m[0] = '\0';
	response_body.size = 0;

	curl_easy_setopt(curl, CURLOPT_URL, "http://localhost/");
	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_body);
	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
	curl_easy_setopt(curl, CURLOPT_USERAGENT, "libcurl-agent/1.0");

	ret = curl_easy_perform(curl);
	if (ret != CURLE_OK) {
		fprintf(stderr, "Error: curl_easy_perform() failed: %s\n", curl_easy_strerror(ret));
		return 1;
	}

	printf("response: [%s]\n", response_body.m);

	free(response_body.m);

	curl_easy_cleanup(curl);

	curl_global_cleanup();

	return 0;
}

size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata)
{
	char *p;
	Memory *mem = (Memory *)userdata;
	size_t append_size = size * nmemb;

	p = (char *)realloc(mem->m, mem->size + append_size + 1);
	if (p == NULL) {
		return 0;
	}
	memcpy(p + mem->size, ptr, append_size);

	mem->m = p;
	mem->size += append_size;
	mem->m[mem->size] = '\0';

	return size * nmemb;
}