lib: introduce curl library

Introduce a new "curl" library which provides simplified bindings for
libcurl easy POST and GET operations.

Signed-off-by: Thibaut VARÈNE <[email protected]>

CMakeLists.txt

@@ -29,6 +29,7 @@ find_library(libubox NAMES ubox)
 find_library(libubus NAMES ubus)
 find_library(libblobmsg_json NAMES blobmsg_json)
 find_package(ZLIB)
+find_package(CURL)
 
 if(LINUX)
   find_library(libnl_tiny NAMES nl-tiny)
@@ -54,6 +55,10 @@ if(ZLIB_FOUND)
   set(DEFAULT_ZLIB_SUPPORT ON)
 endif()
 
+if(CURL_FOUND)
+  set(DEFAULT_CURL_SUPPORT ON)
+endif()
+
 option(DEBUG_SUPPORT "Debug plugin support" ON)
 option(FS_SUPPORT "Filesystem plugin support" ON)
 option(MATH_SUPPORT "Math plugin support" ON)
@@ -67,6 +72,7 @@ option(ULOOP_SUPPORT "Uloop plugin support" ${DEFAULT_ULOOP_SUPPORT})
 option(LOG_SUPPORT "Log plugin support" ON)
 option(SOCKET_SUPPORT "Socket plugin support" ON)
 option(ZLIB_SUPPORT "Zlib plugin support" ${DEFAULT_ZLIB_SUPPORT})
+option(CURL_SUPPORT "Curl plugin support" ${DEFAULT_CURL_SUPPORT})
 
 set(LIB_SEARCH_PATH "${CMAKE_INSTALL_PREFIX}/lib/ucode/*.so:${CMAKE_INSTALL_PREFIX}/share/ucode/*.uc:./*.so:./*.uc" CACHE STRING "Default library search path")
 string(REPLACE ":" "\", \"" LIB_SEARCH_DEFINE "${LIB_SEARCH_PATH}")
@@ -290,6 +296,14 @@ if(ZLIB_SUPPORT)
   target_link_libraries(zlib_lib ZLIB::ZLIB)
 endif()
 
+if(CURL_SUPPORT)
+  set(LIBRARIES ${LIBRARIES} curl_lib)
+  add_library(curl_lib MODULE lib/curl.c)
+  set_target_properties(curl_lib PROPERTIES OUTPUT_NAME curl PREFIX "")
+  target_link_options(curl_lib PRIVATE ${UCODE_MODULE_LINK_OPTIONS})
+  target_link_libraries(curl_lib CURL::libcurl)
+endif()
+
 if(UNIT_TESTING)
   enable_testing()
   add_definitions(-DUNIT_TESTING)

lib/curl.c

@@ -0,0 +1,296 @@
+/*
+ * Copyright (C) 2024 Thibaut VARÈNE <[email protected]>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/**
+ * # Curl bindings
+ *
+ * The `curl` module provides single-call curl bindings through the libcurl-easy API.
+ *
+ * @module curl
+ *
+ * @todo
+ * add support for returning response headers
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <curl/curl.h>
+
+#include "ucode/module.h"
+#include "ucode/platform.h"
+
+
+CURL *
+uc_curl_initurl(uc_vm_t *vm, const char *url)
+{
+	CURL *curl = NULL;
+	CURLcode res;
+
+	res = curl_global_init(CURL_GLOBAL_DEFAULT);
+	if (res != CURLE_OK) {
+		uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Curl init error");
+		goto out;
+	}
+
+	curl = curl_easy_init();
+	if (!curl) {
+		uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Curl easy init error");
+		goto out;
+	}
+
+	res = curl_easy_setopt(curl, CURLOPT_URL, url);
+	if (res != CURLE_OK) {
+		uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Failed to set target URL: %s", curl_easy_strerror(res));
+		goto out;
+	}
+	curl_easy_setopt(curl, CURLOPT_TIMEOUT, 10L);		// 10s timeout
+	curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);	// follow redirects
+
+out:
+	return curl;
+}
+
+/**
+ * POST data to remote URL.
+ *
+ * Throws an exception on errors.
+ *
+ * Returns true on success.
+ *
+ * @function module:curl#post
+ *
+ * @param {string} url
+ * Target URL. for the POST
+ *
+ * @param {string} data
+ * POST data
+ *
+ * @param {?array} headers
+ * Optional extra HTTP headers
+ *
+ * @returns {?boolean}
+ *
+ * @example
+ * const REMOTE_URL = "https://myserver.domain/api/post";
+ * const curl = require('curl');
+ * let gzipdata = ...
+ * let headers = [ "My_Custom_Header:  foobar", "Content_Encoding: gzip" ];
+ * curl.post(REMOTE_URL, gzipdata, headers);
+ */
+static uc_value_t *
+uc_curl_post(uc_vm_t *vm, size_t nargs)
+{
+	uc_value_t *url = uc_fn_arg(0);
+	uc_value_t *src = uc_fn_arg(1);
+	uc_value_t *hdr = uc_fn_arg(2);
+	size_t i, len;
+	CURL *curl = NULL;
+	CURLcode res;
+	struct curl_slist *headers = NULL;
+	bool ret = false;
+
+	if (ucv_type(url) != UC_STRING) {
+		uc_vm_raise_exception(vm, EXCEPTION_TYPE, "Passed url is not a string");
+		goto out;
+	}
+
+	curl = uc_curl_initurl(vm, ucv_string_get(url));
+
+	if (hdr) {
+		if (ucv_type(hdr) != UC_ARRAY) {
+			uc_vm_raise_exception(vm, EXCEPTION_TYPE, "Passed headers is not an array");
+			goto out;
+		}
+
+		len = ucv_array_length(hdr);
+
+		if (len) {
+			for (i = 0; i < len; i++) {
+				/* XXX curl_slist_append(headers, ucv_string_get(ucv_array_get(hdr, i))); fails with
+				 include/ucode/types.h:356:59: error: lvalue required as unary '&' operand
+				   356 | #define ucv_string_get(uv) _ucv_string_get((uc_value_t **)&uv)
+				       |                                                           ^
+				 lib/curl.c:75:70: note: in expansion of macro 'ucv_string_get'
+				    75 |                                 headers = curl_slist_append(headers, ucv_string_get(ucv_array_get(hdr, i)));
+				       |                                                                      ^~~~~~~~~~~~~~
+				*/
+				uc_value_t *h = ucv_array_get(hdr, i);
+				headers = curl_slist_append(headers, ucv_string_get(h));
+				if (!headers) {
+					uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Could not append header: %s", ucv_string_get(h));
+					goto out;
+				}
+			}
+			res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
+			if (res != CURLE_OK) {
+				uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Failed to set POST headers: %s", curl_easy_strerror(res));
+				goto out;
+			}
+		}
+	}
+
+	switch (ucv_type(src)) {
+	case UC_STRING:
+		res = curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, ucv_string_length(src));
+		if (res != CURLE_OK) {
+			uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Failed to set POST size: %s", curl_easy_strerror(res));
+			goto out;
+		}
+		res = curl_easy_setopt(curl, CURLOPT_POSTFIELDS, ucv_string_get(src));
+		if (res != CURLE_OK) {
+			uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Failed to set POST data: %s", curl_easy_strerror(res));
+			goto out;
+		}
+		break;
+
+	case UC_RESOURCE:
+	case UC_OBJECT:
+	case UC_ARRAY:
+	default:
+		uc_vm_raise_exception(vm, EXCEPTION_TYPE, "Unsupported data type");
+		goto out;
+	}
+
+	res = curl_easy_perform(curl);
+	if (res != CURLE_OK) {
+		uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Curl error: %s", curl_easy_strerror(res));
+		goto out;
+	}
+
+	ret = true;
+out:
+	curl_slist_free_all(headers);
+	curl_easy_cleanup(curl);
+	curl_global_cleanup();
+	return ucv_boolean_new(ret);
+}
+
+static size_t
+recv_data(char *ptr, size_t size, size_t nmemb, void *userdata)
+{
+	size_t dsize = size * nmemb;
+	uc_stringbuf_t *outbuf = userdata;
+
+	printbuf_memset(outbuf, printbuf_length(outbuf) + dsize - 1, 0, 1);
+	outbuf->bpos -= dsize;
+
+	memcpy(outbuf->buf + outbuf->bpos, ptr, dsize);
+	outbuf->bpos += dsize;
+
+	return dsize;
+}
+
+/**
+ * GET data from remote URL.
+ *
+ * Throws an exception on errors.
+ *
+ * Returns remote content on success.
+ *
+ * @function module:curl#get
+ *
+ * @param {string} url
+ * Target URL. for the GET
+ *
+ * @param {?array} headers
+ * Optional extra HTTP headers
+ *
+ * @returns {?string}
+ *
+ * @example
+ * const REMOTE_URL = "https://myserver.domain/";
+ * const curl = require('curl');
+ * let content = curl.get(REMOTE_URL);
+ */
+static uc_value_t *
+uc_curl_get(uc_vm_t *vm, size_t nargs)
+{
+	uc_value_t *url = uc_fn_arg(0);
+	uc_value_t *hdr = uc_fn_arg(1);
+	uc_value_t *rv = NULL;
+	uc_stringbuf_t *outbuf;
+	size_t i, len;
+	CURL *curl = NULL;
+	CURLcode res;
+	struct curl_slist *headers = NULL;
+
+	if (ucv_type(url) != UC_STRING) {
+		uc_vm_raise_exception(vm, EXCEPTION_TYPE, "Passed url is not a string");
+		goto out;
+	}
+
+	curl = uc_curl_initurl(vm, ucv_string_get(url));
+
+	if (hdr) {
+		if (ucv_type(hdr) != UC_ARRAY) {
+			uc_vm_raise_exception(vm, EXCEPTION_TYPE, "Passed headers is not an array");
+			goto out;
+		}
+
+		len = ucv_array_length(hdr);
+
+		if (len) {
+			for (i = 0; i < len; i++) {
+				uc_value_t *h = ucv_array_get(hdr, i);
+				headers = curl_slist_append(headers, ucv_string_get(h));
+				if (!headers) {
+					uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Could not append header: %s", ucv_string_get(h));
+					goto out;
+				}
+			}
+			res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
+			if (res != CURLE_OK) {
+				uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Failed to set GET headers: %s", curl_easy_strerror(res));
+				goto out;
+			}
+		}
+	}
+
+	outbuf = ucv_stringbuf_new();
+	res = curl_easy_setopt(curl, CURLOPT_WRITEDATA, outbuf);
+	if (res != CURLE_OK) {
+		uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Failed to set output buffer: %s", curl_easy_strerror(res));
+		printbuf_free(outbuf);
+		goto out;
+	}
+
+	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, recv_data);
+
+	res = curl_easy_perform(curl);
+	if (res != CURLE_OK) {
+		uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "Curl error: %s", curl_easy_strerror(res));
+		printbuf_free(outbuf);
+		goto out;
+	}
+
+	rv = ucv_stringbuf_finish(outbuf);
+
+out:
+	curl_slist_free_all(headers);
+	curl_easy_cleanup(curl);
+	curl_global_cleanup();
+	return rv;
+}
+
+static const uc_function_list_t global_fns[] = {
+	{ "post",	uc_curl_post },
+	{ "get",	uc_curl_get },
+};
+
+void uc_module_init(uc_vm_t *vm, uc_value_t *scope)
+{
+	uc_function_list_register(scope, global_fns);
+}