我到处搜索了这个，我找不到一个像样的代码。如何使用GSOAP 访问Amazon AWS S3 服务？
【问题讨论】：
标签： c++ c amazon-s3 signature gsoap
以下代码来自 OP。最初，该帖子包含问题和答案，我将其转换为问答格式。
签名必须是格式
base64encode((HMAC-SHA1(ActionName+"AmazonS3"+XMLTimestamp)))
HMAC、SHA1 和 B64 实用程序可在 openssl.
SOAP 请求的格式由 wsdl.
REST 接口不同。
wsdl2h 之后生成标头，soapcpp2 生成 GSOAP
客户端代码以下将是访问服务的代码：
使用编译器预处理指令WITH_OPENSSL 构建。链接到
库libeay32 和ssleay32。
#include "AmazonS3SoapBinding.nsmap" //generated from soapcpp2
#include "soapAmazonS3SoapBindingProxy.h" //generated from soapcpp2
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include <openssl/evp.h>
/* convert to base64 */
std::string base64_encodestring(char* text, int len) {
EVP_ENCODE_CTX ectx;
int size = len*2;
size = size > 64 ? size : 64;
unsigned char* out = (unsigned char*)malloc( size );
int outlen = 0;
int tlen = 0;
EVP_EncodeInit(&ectx);
EVP_EncodeUpdate(&ectx,
out,
&outlen,
(const unsigned char*)text,
len
);
tlen += outlen;
EVP_EncodeFinal( &ectx, out+tlen, &outlen );
tlen += outlen;
std::string str((char*)out, tlen );
free( out );
return str;
}
/* return the utc date+time in xml format */
const char* xml_datetime() {
/*"YYYY-mm-ddTHH:MM:SS.000Z\"*/
const int MAX=25;
static char output[MAX+1];
time_t now = time(NULL);
strftime( output, MAX+1, "%Y-%m-%dT%H:%M:%S.000Z", gmtime( &now ) );
std::cout <<output<<std::endl;
return output;
}
/* first argument is the signing key */
/* all subsequent argumets are concatenated */
/* must end list with NULL */
char* aws_signature(char* key, ...) {
unsigned int i, len;
char *data, **list = &key;
static char hmac[EVP_MAX_MD_SIZE];
for (i = 1, len = 0; *(list+i) != NULL; ++i) {
len += strlen( *(list+i) );
}
data = (char*)malloc(sizeof(char) * (len+1));
if (data) {
for ( i = 1, len = 0 ; *(list+i) != NULL ; ++i ) {
strncpy( data+len, *(list+i), strlen(*(list+i)) );
len += strlen(*(list+i));
}
data[len]='\0';
std::cout<<data<<std::endl;
HMAC( EVP_sha1(),
key, strlen(key),
(unsigned char*)data, strlen(data),
(unsigned char*) hmac, &len
);
free(data);
}
std::string b64data=base64_encodestring(hmac, len);
strcpy(hmac,b64data.c_str());
return hmac;
};
int main(void) {
AmazonS3SoapBindingProxy client;
soap_ssl_client_context(&client,
/* for encryption w/o authentication */
SOAP_SSL_NO_AUTHENTICATION,
/* SOAP_SSL_DEFAULT | SOAP_SSL_SKIP_HOST_CHECK, */
/* if we don't want the host name checks since
* these will change from machine to machine */
/*SOAP_SSL_DEFAULT,*/
/* use SOAP_SSL_DEFAULT in production code */
NULL, /* keyfile (cert+key): required only when
client must authenticate to server
(see SSL docs to create this file) */
NULL, /* password to read the keyfile */
NULL, /* optional cacert file to store trusted
certificates, use cacerts.pem for all
public certificates issued by common CAs */
NULL, /* optional capath to directory with trusted
certificates */
NULL /* if randfile!=NULL: use a file with random
data to seed randomness */
);
/* use this if you are behind a proxy server.....
client.proxy_host="proxyserver"; // proxy hostname
client.proxy_port=4250;
client.proxy_userid="username"; // user pass if proxy
client.proxy_passwd="password"; // requires authentication
client.proxy_http_version="1.1"; // http version
*/
_ns1__ListAllMyBuckets buk_req;
_ns1__ListAllMyBucketsResponse buk_resp;
ns1__ListAllMyBucketsResult buk_res;
buk_res.soap=&client;
buk_req.AWSAccessKeyId=new std::string("ACCESSKEY");
buk_req.soap=&client;
/* ListAllMyBuckets is the method I want to call here.
* change it for other S3 services that you wish to call.*/
char *sig=aws_signature(
"SECRETKEY",
"AmazonS3",
"ListAllMyBuckets",
xml_datetime(),
NULL
);
buk_req.Signature=new std::string(sig);
buk_req.Timestamp=new time_t(time(NULL));
buk_resp.soap=&client;
buk_resp.ListAllMyBucketsResponse=&buk_res;
client.ListAllMyBuckets(&buk_req,&buk_resp);
client.soap_stream_fault(std::cout);
std::vector<ns1__ListAllMyBucketsEntry * >::iterator itr;
for(itr=buk_resp.ListAllMyBucketsResponse->Buckets->Bucket.begin();
itr!=buk_resp.ListAllMyBucketsResponse->Buckets->Bucket.end();
itr++
) {
std::cout<<(*itr)->Name<<std::endl;
}
}
【讨论】：
如何使用 GSOAP for C 和 C++ 访问 Amazon AWS S3？
第 1 步
使用 gSOAP 的 wsd2lh 工具将 Amazon 的 S3 WSDL 转换为接口头文件aws-s3.h：
wsdl2h -t typemap.dat -o aws-s3.h http://doc.s3.amazonaws.com/2006-03-01/AmazonS3.wsdl
使用选项-c 生成C 源代码而不是默认的C++ 源代码。 typemap.dat 文件位于 gSOAP 发行版的 gsoap 目录中。
第 2 步
对从 wsdl2h 工具创建的头文件使用 soapcpp2 工具。
soapcpp2 -C -j aws-s3.h
这会从 aws-s3.h 标头生成带有 C++ 服务代理和对象（-j 选项）的客户端代码（-C 选项）。 C 代码省略-j。
第 3 步
使用自动生成的 AmazonS3SoapBindingProxy 代理方法访问 AWS S3 并为 AWS S3 创建 base64 编码的 HMAC-SHA1 哈希签名。签名是一个带有 HMAC-SHA1 哈希字符串 "AmazonS3" + OPERATION_NAME + Timestamp 的 base64 编码版本的字符串：
/*
createbucket.cpp
Example AWS S3 CreateBucket service invocation
*/
#include "soapAmazonS3SoapBindingProxy.h"
#include "AmazonS3SoapBinding.nsmap"
#include <fstream>
// Make allocation of primitive values quick and easy:
template<class T>
T * soap_make(struct soap *soap, T val) {
T *p = (T*)soap_malloc(soap, sizeof(T));
*p = val;
return p;
}
// Make base64-encoded, HMAC-SHA1 hashed signature for AWS S3
std::string soap_make_s3__signature(struct soap *soap, char const *operation, char const *key) {
std::string signature = "AmazonS3";
signature += operation;
char UTCstamp[40]; //to hold ISO 8601 time format
time_t now;
time(&now);
strftime(UTCstamp, sizeof UTCstamp, "%Y-%m-%dT%H:%M:%S.000Z", gmtime(&now));
signature += UTCstamp;
// Get the HMAC-SHA1 digest of the signature string
unsigned char * digest;
digest = HMAC(EVP_sha1(), key, strlen(key),
(unsigned char*)(signature.c_str()),
signature.length(), NULL, NULL);
char signatureBase64[20];
// Convert the digest to base64
soap_s2base64(soap, digest, signatureBase64, sizeof signatureBase64);
return std::string(signatureBase64);
}
// Read access keys from file generated by AWS CLI
bool getAWSKeys(std::string path, std::string user, std::string &accessKey, std::string &secretKey) {
std::ifstream credentialsFile(path.c_str());
if (!credentialsFile.is_open())
return false;
std::string line;
while (std::getline(credentialsFile, line)) {
// Keep going until we get to the desired user
if (line.find(user) == std::string::npos)
continue;
while (std::getline(credentialsFile, line)) {
// Keep going until we get to the access key lines
if (line.find("aws_access_key_id") == std::string::npos)
continue;
// Grab keys and trim whitespace
size_t first, last;
accessKey = line.substr(line.find_first_of('=')+1);
first = accessKey.find_first_not_of(' ');
if (first == std::string::npos)
return false;
last = accessKey.find_last_not_of(' ');
accessKey.substr(first, last-first+1).swap(accessKey);
std::getline(credentialsFile, line);
secretKey = line.substr(line.find_first_of('=')+1);
first = secretKey.find_first_not_of(' ');
if (first == std::string::npos)
return false;
last = secretKey.find_last_not_of(' ');
secretKey.substr(first, last-first+1).swap(secretKey);
return true;
}
}
return false;
}
int main(int argc, char **argv) {
// Load AWS keys from file
std::string accessKey, secretKey;
// Use the path to your AWS credentials file
std::string credentialsFile = (argc > 2 ? argv[2] : "path_to_aws_credentials_file");
std::string user = "default";
if (!getAWSKeys(credentialsFile, user, accessKey, secretKey)) {
std::cout << "Couldn't read AWS keys for user " << user
<< " from file " << credentialsFile << '\n';
return 0;
}
// Create a proxy to invoke AWS S3 services
AmazonS3SoapBindingProxy aws(SOAP_XML_INDENT);
// Create bucket
// Set the arguments of the CreateBucket service operation
_s3__CreateBucket createBucketReq;
std::string bucketName = (argc > 1 ? argv[1] : "BucketName");
createBucketReq.Bucket = bucketName;
createBucketReq.AWSAccessKeyId = soap_new_std__string(aws.soap);
*createBucketReq.AWSAccessKeyId = accessKey;
createBucketReq.Timestamp = soap_make(aws.soap, time(0));
createBucketReq.Signature = soap_new_std__string(aws.soap);
*createBucketReq.Signature = soap_make_s3__signature(aws.soap,
"CreateBucket",
secretKey.c_str());
// Store the result of the service
_s3__CreateBucketResponse createBucketRes;
// Create a bucket
if (aws.CreateBucket(&createBucketReq, createBucketRes)) {
aws.soap_stream_fault(std::cerr);
}
/*
NOTE: you must add the line:
_s3__CreateBucketResponse = $ s3__CreateBucketResult* CreateBucketResponse;
to the typemap.dat file because Amazon's response doesn't match
their promised schema. This adds the variable CreateBucketResponse
to the _s3__CreateBucketResponse class so we can access the response.
*/
else if (createBucketRes.CreateBucketResponse) {
s3__CreateBucketResult &result = *createBucketRes.CreateBucketResponse;
std::cout << "You are the owner of bucket '" << result.BucketName << "'." << std::endl;
}
// Delete all managed data
aws.destroy();
return 0;
}
C 代码看起来很相似，主要区别在于使用函数调用而不是方法调用，即soap_call___s3__CreateBucket(&createBucketReq, &createBucketRes)。所有这些都在生成的aws-s4.h 文件中进行了解释。
使用您的源代码编译生成的文件：
c++ -DSOAP_MAXDIMESIZE=104857600 -DWITH_OPENSSL -o createbucket createbucket.cpp soapAmazonS3SoapBindingProxy.cpp soapC.cpp stdsoap2.cpp -lssl -lcrypto
SOAP_MAXDIMESIZE=104857600 确保 DIME 附件大小可以足够大，同时防止使用 DIME 的拒绝服务攻击。 DIME 标头具有附件大小，因此攻击者可以将其设置为任意大以耗尽内存资源。其他帖子没有提到这一点。
运行createbucket，会创建一个新的bucket。
在最终的 .cpp 文件中，请注意我们在设置 credentialsFile 和 bucketName 时会检查命令行参数 (argv)。这允许使用参数调用程序：
./createbucket BucketName path_to_credentials_file
有关所有这些的更多详细信息，我建议阅读 Chris Moutsos 在How to use AWS S3 in C++ with gSOAP 上撰写的优秀 CodeProject 文章，该解释的部分内容来自该文章。
【讨论】：