Adds a CURL wrapper library to help using libcurl

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

5 files changed, 707 insertions, 1 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index fe260fa..c294717 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -23,7 +23,7 @@
 PROJECT_TARGET_ADD(afb-utilities)
 
     # Define targets
-    ADD_LIBRARY(${TARGET_NAME} STATIC wrap-json.c filescan-utils.c)
+    ADD_LIBRARY(${TARGET_NAME} STATIC curl-wrap.c escape.c wrap-json.c filescan-utils.c)
 
     # Library properties
     SET_TARGET_PROPERTIES(${TARGET_NAME} PROPERTIES
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: */
diff --git a/curl-wrap.h b/curl-wrap.h
new file mode 100644
index 0000000..2e44f47
--- /dev/null
+++ b/curl-wrap.h
@@ -0,0 +1,45 @@
+/*
+ * 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.
+ *
+ */
+
+#pragma once
+
+#include <curl/curl.h>
+
+extern char *curl_wrap_url (const char *base, const char *path,
+                            const char *const *query, size_t * size);
+
+extern int curl_wrap_perform (CURL * curl, char **result, size_t * size);
+
+extern void curl_wrap_do(CURL *curl, void (*callback)(void *closure, int status, CURL *curl, const char *result, size_t size), void *closure);
+
+extern int curl_wrap_content_type_is (CURL * curl, const char *value);
+
+extern CURL *curl_wrap_prepare_get_url(const char *url);
+
+extern CURL *curl_wrap_prepare_get(const char *base, const char *path, const char * const *args);
+
+extern CURL *curl_wrap_prepare_post_url_data(const char *url, const char *datatype, const char *data, size_t szdata);
+
+extern CURL *curl_wrap_prepare_post(const char *base, const char *path, const char * const *args);
+
+extern int curl_wrap_add_header(CURL *curl, const char *header);
+
+extern int curl_wrap_add_header_value(CURL *curl, const char *name, const char *value);
+
+/* vim: set colorcolumn=80: */
+
diff --git a/escape.c b/escape.c
new file mode 100644
index 0000000..3bb25c2
--- /dev/null
+++ b/escape.c
@@ -0,0 +1,428 @@
+/*
+ * 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>
+
+/*
+ * Test if 'c' is to be escaped or not.
+ * Any character that is not in [-.0-9A-Z_a-z~]
+ * must be escaped.
+ * Note that space versus + is not managed here.
+ */
+static inline int should_escape(char c)
+{
+/* ASCII CODES OF UNESCAPED CHARS
+car hx/oct  idx
+'-' 2d/055  1
+'.' 2e/056  2
+'0' 30/060  3
+...         ..
+'9' 39/071  12
+'A' 41/101  13
+...         ..
+'Z' 5a/132  38
+'_' 5f/137  39
+'a' 61/141  40
+...         ..
+'z' 7a/172  65
+'~' 7e/176  66
+*/
+	/* [-.0-9A-Z_a-z~] */
+	if (c <= 'Z') {
+		/* [-.0-9A-Z] */
+		if (c < '0') {
+			/* [-.] */
+			return c != '-' && c != '.';
+		} else {
+			/* [0-9A-Z] */
+			return c < 'A' && c > '9';
+		}
+	} else {
+		/* [_a-z~] */
+		if (c <= 'z') {
+			/* [_a-z] */
+			return c < 'a' && c != '_';
+		} else {
+			/* [~] */
+			return c != '~';
+		}
+	}
+}
+
+/*
+ * returns the ASCII char for the hexadecimal
+ * digit of the binary value 'f'.
+ * returns 0 if f isn't in [0 ... 15].
+ */
+static inline char bin2hex(int f)
+{
+	if ((f & 15) != f)
+		f = 0;
+	else if (f < 10)
+		f += '0';
+	else
+		f += 'A' - 10;
+	return (char)f;
+}
+
+/*
+ * returns the binary value for the hexadecimal
+ * digit whose char is 'c'.
+ * returns -1 if c isn't i n[0-9A-Fa-f]
+ */
+static inline int hex2bin(char c)
+{
+	/* [0-9A-Fa-f] */
+	if (c <= 'F') {
+		/* [0-9A-F] */
+		if (c <= '9') {
+			/* [0-9] */
+			if (c >= '0') {
+				return (int)(c - '0');
+			}
+		} else if (c >= 'A') {
+			/* [A-F] */
+			return (int)(c - ('A' - 10));
+		}
+	} else {
+		/* [a-f] */
+		if (c >= 'a' && c <= 'f') {
+			return (int)(c - ('a' - 10));
+		}
+	}
+	return -1;
+}
+
+/*
+ * returns the length that will have the text 'itext' of length
+ * 'ilen' when escaped. When 'ilen' == 0, strlen is used to
+ * compute the size of 'itext'.
+ */
+static size_t escaped_length(const char *itext, size_t ilen)
+{
+	char c;
+	size_t i, r;
+
+	if (!ilen)
+		ilen = strlen(itext);
+	c = itext[i = r = 0];
+	while (i < ilen) {
+		r += c != ' ' && should_escape(c) ? 3 : 1;
+		c = itext[++i];
+	}
+	return r;
+}
+
+/*
+ * Escapes the text 'itext' of length 'ilen'.
+ * When 'ilen' == 0, strlen is used to compute the size of 'itext'.
+ * The escaped text is put in 'otext' of length 'olen'.
+ * Returns the length of the escaped text (it can be greater than 'olen').
+ * When 'olen' is greater than the needed length, an extra null terminator
+ * is appened to the escaped string.
+ */
+static size_t escape_to(const char *itext, size_t ilen, char *otext, size_t olen)
+{
+	char c;
+	size_t i, r;
+
+	if (!ilen)
+		ilen = strlen(itext);
+	c = itext[i = r = 0];
+	while (i < ilen) {
+		if (c == ' ')
+			c = '+';
+		else if (should_escape(c)) {
+			if (r < olen)
+				otext[r] = '%';
+			r++;
+			if (r < olen)
+				otext[r] = bin2hex((c >> 4) & 15);
+			r++;
+			c = bin2hex(c & 15);
+		}
+		if (r < olen)
+			otext[r] = c;
+		r++;
+		c = itext[++i];
+	}
+	if (r < olen)
+		otext[r] = 0;
+	return r;
+}
+
+/*
+ * returns the length of 'itext' of length 'ilen' that can be unescaped.
+ * compute the size of 'itext' when 'ilen' == 0.
+ */
+static size_t unescapable_length(const char *itext, size_t ilen)
+{
+	char c;
+	size_t i;
+
+	c = itext[i = 0];
+	while (i < ilen) {
+		if (c != '%')
+			i++;
+		else {
+			if (i + 3 > ilen
+			 || hex2bin(itext[i + 1]) < 0
+			 || hex2bin(itext[i + 2]) < 0)
+				break;
+			i += 3;
+		}
+		c = itext[i];
+	}
+	return i;
+}
+
+/*
+ * returns the length that will have the text 'itext' of length
+ * 'ilen' when escaped. When 'ilen' == 0, strlen is used to
+ * compute the size of 'itext'.
+ */
+static size_t unescaped_length(const char *itext, size_t ilen)
+{
+	char c;
+	size_t i, r;
+
+	c = itext[i = r = 0];
+	while (i < ilen) {
+		i += (size_t)(1 + ((c == '%') << 1));
+		r++;
+		c = itext[i];
+	}
+	return r;
+}
+
+static size_t unescape_to(const char *itext, size_t ilen, char *otext, size_t olen)
+{
+	char c;
+	size_t i, r;
+	int h, l;
+
+	ilen = unescapable_length(itext, ilen);
+	c = itext[i = r = 0];
+	while (i < ilen) {
+		if (c != '%') {
+			if (c == '+')
+				c = ' ';
+			i++;
+		} else {
+			if (i + 2 >= ilen)
+				break;
+			h = hex2bin(itext[i + 1]);
+			l = hex2bin(itext[i + 2]);
+			c = (char)((h << 4) | l);
+			i += 3;
+		}
+		if (r < olen)
+			otext[r] = c;
+		r++;
+		c = itext[i];
+	}
+	if (r < olen)
+		otext[r] = 0;
+	return r;
+}
+
+/* create an url */
+char *escape_url(const char *base, const char *path, const char * const *args, size_t *length)
+{
+	int i;
+	size_t lb, lp, lq, l, L;
+	const char *null;
+	char *result;
+
+	/* ensure args */
+	if (!args) {
+		null = NULL;
+		args = &null;
+	}
+
+	/* compute lengths */
+	lb = base ? strlen(base) : 0;
+	lp = path ? strlen(path) : 0;
+	lq = 0;
+	i = 0;
+	while (args[i]) {
+		lq += 1 + escaped_length(args[i], strlen(args[i]));
+		i++;
+		if (args[i])
+			lq += 1 + escaped_length(args[i], strlen(args[i]));
+		i++;
+	}
+
+	/* allocation */
+	L = lb + lp + lq + 1;
+	result = malloc(L + 1);
+	if (result) {
+		/* make the resulting url */
+		l = lb;
+		if (lb) {
+			memcpy(result, base, lb);
+			if (result[l - 1] != '/' && path && path[0] != '/')
+				result[l++] = '/';
+		}
+		if (lp) {
+			memcpy(result + l, path, lp);
+			l += lp;
+		}
+		i = 0;
+		while (args[i]) {
+			if (i) {
+				result[l++] = '&';
+			} else if (base || path) {
+				result[l] = memchr(result, '?', l) ? '&' : '?';
+				l++;
+			}
+			l += escape_to(args[i], strlen(args[i]), result + l, L - l);
+			i++;
+			if (args[i]) {
+				result[l++] = '=';
+				l += escape_to(args[i], strlen(args[i]), result + l, L - l);
+			}
+			i++;
+		}
+		result[l] = 0;
+		if (length)
+			*length = l;
+	}
+	return result;
+}
+
+char *escape_args(const char * const *args, size_t *length)
+{
+	return escape_url(NULL, NULL, args, length);
+}
+
+const char **unescape_args(const char *args)
+{
+	const char **r, **q;
+	char c, *p;
+	size_t j, z, l, n, lt;
+
+	lt = n = 0;
+	if (args[0]) {
+		z = 0;
+		do {
+			l = strcspn(&args[z], "&=");
+			j = 1 + unescaped_length(&args[z], l);
+			lt += j;
+			z += l;
+			c = args[z++];
+			if (c == '=') {
+				l = strcspn(&args[z], "&");
+				j = 1 + unescaped_length(&args[z], l);
+				lt += j;
+				z += l;
+				c = args[z++];
+			}
+			n++;
+		} while(c);
+	}
+
+	l = lt + (2 * n + 1) * sizeof(char *);
+	r = malloc(l);
+	if (!r)
+		return r;
+
+	q = r;
+	p = (void*)&r[2 * n + 1];
+	if (args[0]) {
+		z = 0;
+		do {
+			q[0] = p;
+			l = strcspn(&args[z], "&=");
+			j = 1 + unescape_to(&args[z], l, p, lt);
+			lt -= j;
+			p += j;
+			z += l;
+			c = args[z++];
+			if (c != '=')
+				q[1] = NULL;
+			else {
+				q[1] = p;
+				l = strcspn(&args[z], "&");
+				j = 1 + unescape_to(&args[z], l, p, lt);
+				lt -= j;
+				p += j;
+				z += l;
+				c = args[z++];
+			}
+			q = &q[2];
+		} while(c);
+	}
+	q[0] = NULL;
+	return r;
+}
+
+char *escape(const char *text, size_t textlen, size_t *reslength)
+{
+	size_t len;
+	char *result;
+
+	len = 1 + escaped_length(text, textlen);
+	result = malloc(len);
+	if (result)
+		escape_to(text, textlen, result, len);
+	if (reslength)
+		*reslength = len - 1;
+	return result;
+}
+
+char *unescape(const char *text, size_t textlen, size_t *reslength)
+{
+	size_t len;
+	char *result;
+
+	len = 1 + unescaped_length(text, textlen);
+	result = malloc(len);
+	if (result)
+		unescape_to(text, textlen, result, len);
+	if (reslength)
+		*reslength = len - 1;
+	return result;
+}
+
+#if 1
+#include <stdio.h>
+int main(int ac, char **av)
+{
+	int i;
+	char *x = escape_args((void*)++av, NULL);
+	char *y = escape(x, strlen(x), NULL);
+	char *z = unescape(y, strlen(y), NULL);
+	const char **v = unescape_args(x);
+
+	printf("%s\n%s\n%s\n", x, y, z);
+	free(x);
+	free(y);
+	free(z);
+	i = 0;
+	while(v[i]) {
+		printf("%s=%s / %s=%s\n", av[i], av[i+1], v[i], v[i+1]);
+		i += 2;
+	}
+	free(v);
+	return 0;
+}
+#endif
+/* vim: set colorcolumn=80: */
diff --git a/escape.h b/escape.h
new file mode 100644
index 0000000..7d548db
--- /dev/null
+++ b/escape.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2017 "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.
+ */
+#pragma once
+
+extern char *escape_url(const char *base, const char *path, const char * const *args, size_t *length);
+extern char *escape_args(const char * const *args, size_t *length);
+extern const char **unescape_args(const char *args);
+
+/* vim: set colorcolumn=80: */