C

准备环境

以Linux Ubuntu系统为例，首先需要安装SSL相关工具。

1. 安装openssl库。

   1	apt-get install libssl-dev

2. 安装curl库。

   1	apt-get install libcurl4-openssl-dev

获取SDK

签名SDK只包含签名功能，不包含云服务的SDK功能，云服务SDK请参见SDK。

点此下载SDK与Demo。

解压时选择解压到当前文件夹，解压后目录结构如下：

请求签名与API调用

1. 在main.c中加入以下引用。

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

2. 生成一个sig_params_t类型的变量， 填入AK和SK。
   1. 本示例以AK和SK保存在环境变量中为例，运行本示例前请先在本地环境中设置环境变量HUAWEICLOUD_SDK_AK和HUAWEICLOUD_SDK_SK。以Linux系统为例在本地将已获取的AK/SK设置为环境变量。
      1. 打开终端，输入以下命令打开环境变量配置文件。

         vi ~/.bashrc

      2. 设置环境变量，保存文件并退出编辑器。

         export HUAWEICLOUD_SDK_AK="已获取AK值" 
         export HUAWEICLOUD_SDK_SK="已获取SK值" 

      3. 输入以下命令使配置文件生效。

         source ~/.bashrc

   2. 生成一个sig_params_t类型的变量， 填入已设置的环境变量。

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      sig_params_t params; sig_params_init(&params); // Directly writing AK/SK in code is risky. For security, encrypt your AK/SK and store them in the configuration file or environment variables. // In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, set environment variables HUAWEICLOUD_SDK_AK and HUAWEICLOUD_SDK_SK. sig_str_t ak = sig_str(getenv("HUAWEICLOUD_SDK_AK")); sig_str_t sk = sig_str(getenv("HUAWEICLOUD_SDK_SK")); params.key = ak; params.secret = sk;

3. 指定方法名、域名、请求uri、查询字符串和body。

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   sig_str_t host = sig_str("service.region.example.com"); sig_str_t method = sig_str("GET"); sig_str_t uri = sig_str("/v1/{project_id}/vpcs"); sig_str_t query_str = sig_str("limit=2"); sig_str_t payload = sig_str(""); params.host = host; params.method = method; params.uri = uri; params.query_str = query_str; params.payload = payload;

4. 增加头部参数，或者其他用途的头域，如多项目场景中添加X-Project-Id，或者全局服务场景中添加X-Domain-Id。

   1 2	//Add header parameters, for example, X-Domain-Id for invoking a global service and X-Project-Id for invoking a project-level service. sig_headers_add(&params.headers, "X-Project-Id", "xxx");

5. 进行签名，执行此函数会将生成的签名头加入request变量中。

   1	sig_sign(&params);

6. 使用curl库访问API，查看访问结果。

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   static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp) { size_t realsize = size * nmemb; struct MemoryStruct *mem = (struct MemoryStruct *)userp; mem->memory = (char*)realloc(mem->memory, mem->size + realsize + 1); if (mem->memory == NULL) { /* out of memory! */ printf("not enough memory (realloc returned NULL)\n"); return 0; } memcpy(&(mem->memory[mem->size]), contents, realsize); mem->size += realsize; mem->memory[mem->size] = 0; return realsize; } //send http request using curl library int perform_request(RequestParams* request) { CURL *curl; CURLcode res; struct MemoryStruct resp_header; resp_header.memory = malloc(1); resp_header.size = 0; struct MemoryStruct resp_body; resp_body.memory = malloc(1); resp_body.size = 0; curl_global_init(CURL_GLOBAL_ALL); curl = curl_easy_init(); curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, params.method.data); char url[1024]; sig_snprintf(url, 1024, "http://%V%V?%V", &params.host, &params.uri, &params.query_str); curl_easy_setopt(curl, CURLOPT_URL, url); struct curl_slist *chunk = NULL; for (int i = 0; i < params.headers.len; i++) { char header[1024]; sig_snprintf(header, 1024, "%V: %V", &params.headers.data[i].name, &params.headers.data[i].value); printf("%s\n", header); chunk = curl_slist_append(chunk, header); } printf("-------------\n"); curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk); curl_easy_setopt(curl, CURLOPT_POSTFIELDS, params.payload.data); curl_easy_setopt(curl, CURLOPT_NOBODY, 0L); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteMemoryCallback); curl_easy_setopt(curl, CURLOPT_HEADERDATA, (void *)&resp_header); curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&resp_body); //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); res = curl_easy_perform(curl); if (res != CURLE_OK) { fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); } else { long status; curl_easy_getinfo(curl, CURLINFO_HTTP_CODE, &status); printf("status %d\n", status); printf(resp_header.memory); printf(resp_body.memory); } free(resp_header.memory); free(resp_body.memory); curl_easy_cleanup(curl); curl_global_cleanup(); //free signature params sig_params_free(&params); return 0; }

7. 运行make命令编译，得到可执行文件main，执行main文件，查看结果。