Adds a CURL wrapper library to help using libcurl

Change-Id: If73bab16a5d4a5258f730c599630bd5fa8e5684f
Signed-off-by: Romain Forlot <romain.forlot@iot.bzh>

1 files changed, 210 insertions, 0 deletions

diff --git a/curl-wrap.c b/curl-wrap.c
new file mode 100644
index 0000000..3c566a3
--- /dev/null
+++ b/curl-wrap.c
@@ -0,0 +1,210 @@
+/*
+ * Copyright (C) 2015, 2016 "IoT.bzh"
+ * Author: José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#define _GNU_SOURCE
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include <curl/curl.h>
+
+#include "curl-wrap.h"
+#include "escape.h"
+
+
+/* internal representation of buffers */
+struct buffer {
+	size_t size;
+	char *data;
+};
+
+/* write callback for filling buffers with the response */
+static size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata)
+{
+	struct buffer *buffer = userdata;
+	size_t sz = size * nmemb;
+	size_t old_size = buffer->size;
+	size_t new_size = old_size + sz;
+	char *data = realloc(buffer->data, new_size + 1);
+	if (!data)
+		return 0;
+	memcpy(&data[old_size], ptr, sz);
+	data[new_size] = 0;
+	buffer->size = new_size;
+	buffer->data = data;
+	return sz;
+}
+
+/* 
+ * Perform the CURL operation for 'curl' and put the result in
+ * memory. If 'result' isn't NULL it receives the returned content
+ * that then must be freed. If 'size' isn't NULL, it receives the
+ * size of the returned content. Note that if not NULL, the real
+ * content is one byte greater than the read size and the last byte
+ * zero. This facility allows to handle the returned content as a
+ * null terminated C-string.
+ */
+int curl_wrap_perform(CURL *curl, char **result, size_t *size)
+{
+	int rc;
+	struct buffer buffer;
+	CURLcode code;
+
+	/* init tthe buffer */
+	buffer.size = 0;
+	buffer.data = NULL;
+
+	/* Perform the request, res will get the return code */ 
+	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
+	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buffer);
+
+	/* Perform the request, res will get the return code */ 
+	code = curl_easy_perform(curl);
+	rc = code == CURLE_OK;
+
+	/* Check for no errors */ 
+	if (rc) {
+		/* no error */
+		if (size)
+			*size = buffer.size;
+		if (result)
+			*result = buffer.data;
+		else
+			free(buffer.data);
+	} else {
+		/* had error */
+		if (size)
+			*size = 0;
+		if (result)
+			*result = NULL;
+		free(buffer.data);
+	}
+
+	return rc;
+}
+
+void curl_wrap_do(CURL *curl, void (*callback)(void *closure, int status, CURL *curl, const char *result, size_t size), void *closure)
+{
+	int rc;
+	char *result;
+	size_t size;
+	char errbuf[CURL_ERROR_SIZE];
+
+	curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errbuf);
+	rc = curl_wrap_perform(curl, &result, &size);
+	if (rc)
+		callback(closure, rc, curl, result, size);
+	else
+		callback(closure, rc, curl, errbuf, 0);
+	free(result);
+	curl_easy_cleanup(curl);
+}
+
+int curl_wrap_content_type_is(CURL *curl, const char *value)
+{
+	char *actual;
+	CURLcode code;
+
+	code = curl_easy_getinfo(curl, CURLINFO_CONTENT_TYPE, &actual);
+	if (code != CURLE_OK || !actual)
+		return 0;
+
+	return !strncasecmp(actual, value, strcspn(actual, "; "));
+}
+
+CURL *curl_wrap_prepare_get_url(const char *url)
+{
+	CURL *curl;
+	CURLcode code;
+
+	curl = curl_easy_init();
+	if(curl) {
+		code = curl_easy_setopt(curl, CURLOPT_URL, url);
+		if (code == CURLE_OK)
+			return curl;
+		curl_easy_cleanup(curl);
+	}
+	return NULL;
+}
+
+CURL *curl_wrap_prepare_get(const char *base, const char *path, const char * const *args)
+{
+	CURL *res;
+	char *url;
+
+	url = escape_url(base, path, args, NULL);
+	res = url ? curl_wrap_prepare_get_url(url) : NULL;
+	free(url);
+	return res;
+}
+
+int curl_wrap_add_header(CURL *curl, const char *header)
+{
+	int rc;
+	struct curl_slist *list;
+
+	list = curl_slist_append(NULL, header);
+	rc = list ? curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list) == CURLE_OK : 0;
+/*
+	curl_slist_free_all(list);
+*/
+	return rc;
+}
+
+int curl_wrap_add_header_value(CURL *curl, const char *name, const char *value)
+{
+	char *h;
+	int rc;
+
+	rc = asprintf(&h, "%s: %s", name, value);
+	rc = rc < 0 ? 0 : curl_wrap_add_header(curl, h);
+	free(h);
+	return rc;
+}
+
+
+CURL *curl_wrap_prepare_post_url_data(const char *url, const char *datatype, const char *data, size_t szdata)
+{
+	CURL *curl;
+
+	curl = curl_easy_init();
+	if (curl
+	 && CURLE_OK == curl_easy_setopt(curl, CURLOPT_URL, url)
+	 && (!szdata || CURLE_OK == curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, szdata))
+	 && CURLE_OK == curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data)
+	 && (!datatype || curl_wrap_add_header_value(curl, "content-type", datatype)))
+		return curl;
+	curl_easy_cleanup(curl);
+	return NULL;
+}
+
+CURL *curl_wrap_prepare_post(const char *base, const char *path, const char * const *args)
+{
+	CURL *res;
+	char *url;
+	char *data;
+	size_t szdata;
+
+	url = escape_url(base, path, NULL, NULL);
+	data = escape_args(args, &szdata);
+	res = url ? curl_wrap_prepare_post_url_data(url, NULL, data, szdata) : NULL;
+	free(url);
+	return res;
+}
+
+/* vim: set colorcolumn=80: */