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 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  * Copyright by The HDF Group.                                               *
  * All rights reserved.                                                      *
  *                                                                           *
  * This file is part of HDF5.  The full HDF5 copyright notice, including     *
  * terms governing use, modification, and redistribution, is contained in    *
  * the COPYING file, which can be found at the root of the source code       *
  * distribution tree, or in https://www.hdfgroup.org/licenses.               *
  * If you do not have access to either file, you may request a copy from     *
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
 /*****************************************************************************
  * Read-Only S3 Virtual File Driver (VFD)
  *
  * This is the header for the S3 Communications module
  *
  * ***NOT A FILE DRIVER***
  *
  * Purpose:
  *
  *     - Provide structures and functions related to communicating with
  *       Amazon S3 (Simple Storage Service).
  *     - Abstract away the REST API (HTTP,
  *       networked communications) behind a series of uniform function calls.
  *     - Handle AWS4 authentication, if appropriate.
  *     - Fail predictably in event of errors.
  *     - Eventually, support more S3 operations, such as creating, writing to,
  *       and removing Objects remotely.
  *
  *     translates:
  *     `read(some_file, bytes_offset, bytes_length, &dest_buffer);`
  *     to:
  *     ```
  *     GET myfile HTTP/1.1
  *     Host: somewhere.me
  *     Range: bytes=4096-5115
  *     ```
  *     and places received bytes from HTTP response...
  *     ```
  *     HTTP/1.1 206 Partial-Content
  *     Content-Range: 4096-5115/63239
  *
  *     <bytes>
  *     ```
  *     ...in destination buffer.
  *
  *****************************************************************************/
 
 #include "H5private.h" /* Generic Functions        */
 
 #ifdef H5_HAVE_ROS3_VFD
 
 /* Necessary S3 headers */
 #include <curl/curl.h>
 #include <openssl/evp.h>
 #include <openssl/hmac.h>
 #include <openssl/sha.h>
 
 /*****************
  * PUBLIC MACROS *
  *****************/
 
 /* hexadecimal string of pre-computed sha256 checksum of the empty string
  * hex(sha256sum(""))
  */
 #define EMPTY_SHA256 "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
 
 /* string length (plus null terminator)
  * example ISO8601-format string: "20170713T145903Z" (YYYYmmdd'T'HHMMSS'_')
  */
 #define ISO8601_SIZE 17
 
 /* string length (plus null terminator)
  * example RFC7231-format string: "Fri, 30 Jun 2017 20:41:55 GMT"
  */
 #define RFC7231_SIZE 30
 
 /*---------------------------------------------------------------------------
  *
  * Macro: ISO8601NOW()
  *
  * Purpose:
  *
  *     write "YYYYmmdd'T'HHMMSS'Z'" (less single-quotes) to dest
  *     e.g., "20170630T204155Z"
  *
  *     wrapper for strftime()
  *
  *     It is left to the programmer to check return value of
  *     ISO8601NOW (should equal ISO8601_SIZE - 1).
  *
  *---------------------------------------------------------------------------
  */
 #define ISO8601NOW(dest, now_gm) strftime((dest), ISO8601_SIZE, "%Y%m%dT%H%M%SZ", (now_gm))
 
 /*---------------------------------------------------------------------------
  *
  * Macro: RFC7231NOW()
  *
  * Purpose:
  *
  *     write "Day, dd Mmm YYYY HH:MM:SS GMT" to dest
  *     e.g., "Fri, 30 Jun 2017 20:41:55 GMT"
  *
  *     wrapper for strftime()
  *
  *     It is left to the programmer to check return value of
  *     RFC7231NOW (should equal RFC7231_SIZE - 1).
  *
  *---------------------------------------------------------------------------
  */
 #define RFC7231NOW(dest, now_gm) strftime((dest), RFC7231_SIZE, "%a, %d %b %Y %H:%M:%S GMT", (now_gm))
 
 /* Reasonable maximum length of a credential string.
  * Provided for error-checking S3COMMS_FORMAT_CREDENTIAL (below).
  *  17 <- "////aws4_request\0"
  *   2 < "s3" (service)
  *   8 <- "YYYYmmdd" (date)
  * 128 <- (access_id)
  * 155 :: sum
  */
 #define S3COMMS_MAX_CREDENTIAL_SIZE 155
 
 /*---------------------------------------------------------------------------
  *
  * Macro: H5FD_S3COMMS_FORMAT_CREDENTIAL()
  *
  * Purpose:
  *
  *     Format "S3 Credential" string from inputs, for AWS4.
  *
  *     Wrapper for snprintf().
  *
  *     _HAS NO ERROR-CHECKING FACILITIES_
  *     It is left to programmer to ensure that return value confers success.
  *     e.g.,
  *     ```
  *     assert( S3COMMS_MAX_CREDENTIAL_SIZE >=
  *             S3COMMS_FORMAT_CREDENTIAL(...) );
  *     ```
  *
  *     "<access-id>/<date>/<aws-region>/<aws-service>/aws4_request"
  *     assuming that `dest` has adequate space.
  *
  *     ALL inputs must be null-terminated strings.
  *
  *     `access` should be the user's access key ID.
  *     `date` must be of format "YYYYmmdd".
  *     `region` should be relevant AWS region, i.e. "us-east-1".
  *     `service` should be "s3".
  *
  *---------------------------------------------------------------------------
  */
 #define S3COMMS_FORMAT_CREDENTIAL(dest, access, iso8601_date, region, service)                               \
     snprintf((dest), S3COMMS_MAX_CREDENTIAL_SIZE, "%s/%s/%s/%s/aws4_request", (access), (iso8601_date),      \
              (region), (service))
 
 /*********************
  * PUBLIC STRUCTURES *
  *********************/
 
 /*----------------------------------------------------------------------------
  *
  * Structure: hrb_node_t
  *
  * HTTP Header Field Node
  *
  *
  *
  * Maintain a ordered (linked) list of HTTP Header fields.
  *
  * Provides efficient access and manipulation of a logical sequence of
  * HTTP header fields, of particular use when composing an
  * "S3 Canonical Request" for authentication.
  *
  * - The creation of a Canonical Request involves:
  *     - convert field names to lower case
  *     - sort by this lower-case name
  *     - convert ": " name-value separator in HTTP string to ":"
  *     - get sorted lowercase names without field or separator
  *
  * As HTTP headers allow headers in any order (excepting the case of multiple
  * headers with the same name), the list ordering can be optimized for Canonical
  * Request creation, suggesting alphabtical order. For more expedient insertion
  * and removal of elements in the list, linked list seems preferable to a
  * dynamically-expanding array. The usually-smaller number of entries (5 or
  * fewer) makes performance overhead of traversing the list trivial.
  *
  * The above requirements of creating at Canonical Request suggests a reasonable
  * trade-off of speed for space with the option to compute elements as needed
  * or to have the various elements prepared and stored in the structure
  * (e.g. name, value, lowername, concatenated name:value)
  * The structure currently is implemented to pre-compute.
  *
  * At all times, the "first" node of the list should be the least,
  * alphabetically. For all nodes, the `next` node should be either NULL or
  * of greater alphabetical value.
  *
  * Each node contains its own header field information, plus a pointer to the
  * next node.
  *
  * It is not allowed to have multiple nodes with the same _lowercase_ `name`s
  * in the same list
  * (i.e., name is case-insensitive for access and modification.)
  *
  * All data (`name`, `value`, `lowername`, and `cat`) are null-terminated
  * strings allocated specifically for their node.
  *
  * `name` (char *)
  *
  *     Case-meaningful name of the HTTP field.
  *     Given case is how it is supplied to networking code.
  *     e.g., "Range"
  *
  * `lowername` (char *)
  *
  *     Lowercase copy of name.
  *     e.g., "range"
  *
  * `value` (char *)
  *
  *     Case-meaningful value of HTTP field.
  *     e.g., "bytes=0-9"
  *
  * `cat` (char *)
  *
  *     Concatenated, null-terminated string of HTTP header line,
  *     as the field would appear in an HTTP request.
  *     e.g., "Range: bytes=0-9"
  *
  * `next` (hrb_node_t *)
  *
  *     Pointers to next node in the list, or NULL sentinel as end of list.
  *     Next node must have a greater `lowername` as determined by strcmp().
  *
  *----------------------------------------------------------------------------
  */
 typedef struct hrb_node_t {
     char              *name;
     char              *value;
     char              *cat;
     char              *lowername;
     struct hrb_node_t *next;
 } hrb_node_t;
 
 /*----------------------------------------------------------------------------
  *
  * Structure: hrb_t
  *
  * HTTP Request Buffer structure
  *
  *
  *
  * Logically represent an HTTP request
  *
  *     GET /myplace/myfile.h5 HTTP/1.1
  *     Host: over.rainbow.oz
  *     Date: Fri, 01 Dec 2017 12:35:04 CST
  *
  *     <body>
  *
  * ...with fast, efficient access to and modification of primary and field
  * elements.
  *
  * Structure for building HTTP requests while hiding much of the string
  * processing required "under the hood."
  *
  * Information about the request target -- the first line -- and the body text,
  * if any, are managed directly with this structure. All header fields, e.g.,
  * "Host" and "Date" above, are created with a linked list of `hrb_node_t` and
  * included in the request by a pointer to the head of the list.
  *
  *
  * `body` (char *) :
  *
  *     Pointer to start of HTTP body.
  *
  *     Can be NULL, in which case it is treated as the empty string, "".
  *
  * `body_len` (size_t) :
  *
  *     Number of bytes (characters) in `body`. 0 if empty or NULL `body`.
  *
  * `first_header` (hrb_node_t *) :
  *
  *     Pointer to first SORTED header node, if any.
  *     It is left to the programmer to ensure that this node and associated
  *     list is destroyed when done.
  *
  * `resource` (char *) :
  *
  *     Pointer to resource URL string, e.g., "/folder/page.xhtml".
  *
  * `verb` (char *) :
  *
  *     Pointer to HTTP verb string, e.g., "GET".
  *
  * `version` (char *) :
  *
  *     Pointer to HTTP version string, e.g., "HTTP/1.1".
  *
  *----------------------------------------------------------------------------
  */
 typedef struct {
     char       *body;
     size_t      body_len;
     hrb_node_t *first_header;
     char       *resource;
     char       *verb;
     char       *version;
 } hrb_t;
 
 /*----------------------------------------------------------------------------
  *
  * Structure: parsed_url_t
  *
  *
  * Represent a URL with easily-accessed pointers to logical elements within.
  * These elements (components) are stored as null-terminated strings (or just
  * NULLs). These components should be allocated for the structure, making the
  * data as safe as possible from modification. If a component is NULL, it is
  * either implicit in or absent from the URL.
  *
  * "http://mybucket.s3.amazonaws.com:8080/somefile.h5?param=value&arg=value"
  *  ^--^   ^-----------------------^ ^--^ ^---------^ ^-------------------^
  * Scheme             Host           Port  Resource        Query/-ies
  *
  *
  * `scheme` (char *)
  *
  *     String representing which protocol is to be expected.
  *     _Must_ be present.
  *     "http", "https", "ftp", e.g.
  *
  * `host` (char *)
  *
  *     String of host, either domain name, IPv4, or IPv6 format.
  *     _Must_ be present.
  *     "over.rainbow.oz", "192.168.0.1", "[0000:0000:0000:0001]"
  *
  * `port` (char *)
  *
  *     String representation of specified port. Must resolve to a valid unsigned
  *     integer.
  *     "9000", "80"
  *
  * `path` (char *)
  *
  *     Path to resource on host. If not specified, assumes root "/".
  *     "lollipop_guild.wav", "characters/witches/white.dat"
  *
  * `query` (char *)
  *
  *     Single string of all query parameters in url (if any).
  *     "arg1=value1&arg2=value2"
  *
  *----------------------------------------------------------------------------
  */
 typedef struct {
     char *scheme; /* required */
     char *host;   /* required */
     char *port;
     char *path;
     char *query;
 } parsed_url_t;
 
 /*----------------------------------------------------------------------------
  *
  * Structure: s3r_t
  *
  *
  *
  * S3 request structure "handle".
  *
  * Holds persistent information for Amazon S3 requests.
  *
  * Instantiated through `H5FD_s3comms_s3r_open()`, copies data into self.
  *
  * Intended to be re-used for operations on a remote object.
  *
  * Cleaned up through `H5FD_s3comms_s3r_close()`.
  *
  * _DO NOT_ share handle between threads: curl easy handle `curlhandle` has
  * undefined behavior if called to perform in multiple threads.
  *
  *
  * `curlhandle` (CURL)
  *
  *     Pointer to the curl_easy handle generated for the request.
  *
  * `httpverb` (char *)
  *
  *     Pointer to NULL-terminated string. HTTP verb,
  *     e.g. "GET", "HEAD", "PUT", etc.
  *
  *     Default is NULL, resulting in a "GET" request.
  *
  * `purl` (parsed_url_t *)
  *
  *     Pointer to structure holding the elements of URL for file open.
  *
  *     e.g., "http://bucket.aws.com:8080/myfile.dat?q1=v1&q2=v2"
  *     parsed into...
  *     {   scheme: "http"
  *         host:   "bucket.aws.com"
  *         port:   "8080"
  *         path:   "myfile.dat"
  *         query:  "q1=v1&q2=v2"
  *     }
  *
  *     Cannot be NULL.
  *
  * `region` (char *)
  *
  *     Pointer to NULL-terminated string, specifying S3 "region",
  *     e.g., "us-east-1".
  *
  *     Required to authenticate.
  *
  * `secret_id` (char *)
  *
  *     Pointer to NULL-terminated string for "secret" access id to S3 resource.
  *
  *     Required to authenticate.
  *
  * `signing_key` (unsigned char *)
  *
  *     Pointer to `SHA256_DIGEST_LENGTH`-long string for "reusable" signing
  *     key, generated via
  *     `HMAC-SHA256(HMAC-SHA256(HMAC-SHA256(HMAC-SHA256("AWS4<secret_key>",
  *         "<yyyyMMDD"), "<aws-region>"), "<aws-service>"), "aws4_request")`
  *     which may be re-used for several (up to seven (7)) days from creation?
  *     Computed once upon file open.
  *
  *     Required to authenticate.
  *
  *----------------------------------------------------------------------------
  */
 typedef struct {
     CURL          *curlhandle;
     size_t         filesize;
     char          *httpverb;
     parsed_url_t  *purl;
     char          *region;
     char          *secret_id;
     unsigned char *signing_key;
     char          *token;
 } s3r_t;
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /*******************************************
  * DECLARATION OF HTTP FIELD LIST ROUTINES *
  *******************************************/
 
 H5_DLL herr_t H5FD_s3comms_hrb_node_set(hrb_node_t **L, const char *name, const char *value);
 
 /***********************************************
  * DECLARATION OF HTTP REQUEST BUFFER ROUTINES *
  ***********************************************/
 
 H5_DLL herr_t H5FD_s3comms_hrb_destroy(hrb_t **buf);
 
 H5_DLL hrb_t *H5FD_s3comms_hrb_init_request(const char *verb, const char *resource, const char *host);
 
 /*************************************
  * DECLARATION OF S3REQUEST ROUTINES *
  *************************************/
 
 H5_DLL herr_t H5FD_s3comms_s3r_close(s3r_t *handle);
 
 H5_DLL size_t H5FD_s3comms_s3r_get_filesize(s3r_t *handle);
 
 H5_DLL s3r_t *H5FD_s3comms_s3r_open(const char url[], const char region[], const char id[],
                                     const unsigned char signing_key[], const char token[]);
 
 H5_DLL herr_t H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest);
 
 /*********************************
  * DECLARATION OF OTHER ROUTINES *
  *********************************/
 
 H5_DLL struct tm *gmnow(void);
 
 H5_DLL herr_t H5FD_s3comms_aws_canonical_request(char *canonical_request_dest, int cr_size,
                                                  char *signed_headers_dest, int sh_size, hrb_t *http_request);
 
 H5_DLL herr_t H5FD_s3comms_bytes_to_hex(char *dest, const unsigned char *msg, size_t msg_len, bool lowercase);
 
 H5_DLL herr_t H5FD_s3comms_free_purl(parsed_url_t *purl);
 
 H5_DLL herr_t H5FD_s3comms_HMAC_SHA256(const unsigned char *key, size_t key_len, const char *msg,
                                        size_t msg_len, char *dest);
 
 H5_DLL herr_t H5FD_s3comms_load_aws_profile(const char *name, char *key_id_out, char *secret_access_key_out,
                                             char *aws_region_out);
 
 H5_DLL herr_t H5FD_s3comms_parse_url(const char *str, parsed_url_t **purl);
 
 H5_DLL herr_t H5FD_s3comms_signing_key(unsigned char *md, const char *secret, const char *region,
                                        const char *iso8601now);
 
 H5_DLL herr_t H5FD_s3comms_tostringtosign(char *dest, const char *req_str, const char *now,
                                           const char *region);
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* H5_HAVE_ROS3_VFD */

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