Add support for API Key authentication (#313)

This adds support for authenticating using API Keys.

The DSN editor has been updated to take a new "API Key" field. This
field is enabled iif no Username and Password are provided.
The field is stored in the DSN string and then used in every request for
respective configured connection.

driver/connect.c

@@ -35,6 +35,10 @@
 #define HTTP_CONTENT_TYPE_JSON	"Content-Type: " HTTP_APP_JSON \
 	"; charset=utf-8"
 
+/* HTTP header API Key authentication-specific */
+#define HTTP_AUTH_API_KEY		"Authorization: ApiKey "
+#define APIKEY_BUFF_SIZE		512
+
 /* Elasticsearch/SQL data types */
 /* 2 */
 #define TYPE_IP				"IP"
@@ -382,6 +386,10 @@ static void cleanup_curl(esodbc_dbc_st *dbc)
 		return;
 	}
 	DBGH(dbc, "libcurl: handle 0x%p cleanup.", dbc->curl);
+	if (dbc->curl_hdrs) {
+		curl_slist_free_all(dbc->curl_hdrs);
+		dbc->curl_hdrs = NULL;
+	}
 	dbc->curl_err = CURLE_OK;
 	dbc->curl_err_buff[0] = '\0';
 
@@ -442,11 +450,34 @@ SQLRETURN dbc_curl_set_url(esodbc_dbc_st *dbc, int url_type)
 	return SQL_ERROR;
 }
 
+/* copy of unexported Curl_slist_duplicate() libcurl function */
+static struct curl_slist *curl_slist_duplicate(struct curl_slist *inlist)
+{
+	struct curl_slist *outlist = NULL;
+	struct curl_slist *tmp;
+
+	while(inlist) {
+		tmp = curl_slist_append(outlist, inlist->data);
+
+		if(!tmp) {
+			curl_slist_free_all(outlist);
+			return NULL;
+		}
+
+		outlist = tmp;
+		inlist = inlist->next;
+	}
+	return outlist;
+}
+
 static SQLRETURN dbc_curl_init(esodbc_dbc_st *dbc)
 {
 	CURL *curl;
 	SQLRETURN ret;
 	BOOL compress;
+	char apikey_buff[APIKEY_BUFF_SIZE], *apikey_ptr = NULL;
+	struct curl_slist *curl_hdrs;
+
 
 	assert(! dbc->curl);
 
@@ -467,14 +498,6 @@ static SQLRETURN dbc_curl_init(esodbc_dbc_st *dbc)
 		goto err;
 	}
 
-	/* set the HTTP headers: Content-Type, Accept */
-	dbc->curl_err = curl_easy_setopt(curl, CURLOPT_HTTPHEADER,
-			dbc->pack_json ? json_headers : cbor_headers);
-	if (dbc->curl_err != CURLE_OK) {
-		ERRH(dbc, "libcurl: failed to set HTTP headers list.");
-		goto err;
-	}
-
 	/* set the behavior for redirection */
 	dbc->curl_err = curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION,
 			dbc->follow);
@@ -582,8 +605,55 @@ static SQLRETURN dbc_curl_init(esodbc_dbc_st *dbc)
 				goto err;
 			}
 		}
+	} else if (dbc->api_key.cnt) {
+		if (sizeof(HTTP_AUTH_API_KEY) + dbc->api_key.cnt <
+			sizeof(apikey_buff)) {
+			apikey_ptr = apikey_buff;
+		} else {
+			DBGH(dbc, "static buffer size %zuB less than required %zuB, "
+				"allocating.", sizeof(apikey_buff), sizeof(HTTP_AUTH_API_KEY) +
+				dbc->api_key.cnt);
+			apikey_ptr = malloc(sizeof(HTTP_AUTH_API_KEY) + dbc->api_key.cnt);
+			if (! apikey_ptr) {
+				ERRNH(dbc, "OOM for %zuB.", sizeof(HTTP_AUTH_API_KEY) +
+					dbc->api_key.cnt);
+				goto err;
+			}
+		}
+		memcpy(apikey_ptr, HTTP_AUTH_API_KEY, sizeof(HTTP_AUTH_API_KEY) - 1);
+		memcpy(apikey_ptr + sizeof(HTTP_AUTH_API_KEY) - 1, dbc->api_key.str,
+			dbc->api_key.cnt);
+		apikey_ptr[sizeof(HTTP_AUTH_API_KEY) - 1 + dbc->api_key.cnt] = '\0';
+
+		dbc->curl_hdrs = curl_slist_append(NULL, apikey_ptr);
+		if (apikey_ptr != apikey_buff) {
+			free(apikey_ptr);
+			apikey_ptr = NULL;
+		}
+		if (! dbc->curl_hdrs) {
+			ERRH(dbc, "libcurl: failed to init API key Auth header.");
+			goto err;
+		}
 	} else {
-		INFOH(dbc, "no username provided: auth disabled.");
+		INFOH(dbc, "no username or API key provided: auth disabled.");
+	}
+
+	/* set the HTTP headers: Content-Type, Accept, Authorization(?) */
+	curl_hdrs = dbc->pack_json ? json_headers : cbor_headers;
+	/* is there already an Autorization header set? then chain the pack hdrs */
+	if (dbc->curl_hdrs) {
+		if (! (curl_hdrs = curl_slist_duplicate(curl_hdrs))) {
+			ERRNH(dbc, "failed duplicating packing format headers.");
+			goto err;
+		}
+		dbc->curl_hdrs->next = curl_hdrs;
+		/* if there's no Authz header, the pack headers won't be dup'd */
+		curl_hdrs = dbc->curl_hdrs;
+	}
+	dbc->curl_err = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, curl_hdrs);
+	if (dbc->curl_err != CURLE_OK) {
+		ERRH(dbc, "libcurl: failed to set HTTP headers list.");
+		goto err;
 	}
 
 	/* proxy parameters */
@@ -1322,6 +1392,14 @@ SQLRETURN config_dbc(esodbc_dbc_st *dbc, esodbc_dsn_attrs_st *attrs)
 			/* indicates the presence of a non-empty password */
 			INFOH(dbc, "connection PWD: " ESODBC_PWD_VAL_SUBST ".");
 		}
+	} else if (attrs->api_key.cnt) {
+		if (! wstr_to_utf8(&attrs->api_key, &dbc->api_key)) {
+			ERRH(dbc, "failed to convert API key [%zu] `" LWPDL "` to UTF8.",
+				attrs->api_key.cnt, LWSTR(&attrs->api_key));
+			SET_HDIAG(dbc, SQL_STATE_HY000, "API key UTF8 conversion failed",
+				0);
+			goto err;
+		}
 	}
 
 	/* "follow location" param for liburl */

driver/dsn.c

@@ -33,7 +33,8 @@ void TEST_API init_dsn_attrs(esodbc_dsn_attrs_st *attrs)
 static inline wstr_st *mask_pwd(wstr_st *attr, wstr_st *val)
 {
 	static wstr_st subst = WSTR_INIT(ESODBC_PWD_VAL_SUBST);
-	return EQ_CASE_WSTR(attr, &MK_WSTR(ESODBC_DSN_PWD)) ? &subst : val;
+	return EQ_CASE_WSTR(attr, &MK_WSTR(ESODBC_DSN_PWD)) ||
+		EQ_CASE_WSTR(attr, &MK_WSTR(ESODBC_DSN_API_KEY)) ? &subst : val;
 }
 
 #define DSN_NOT_MATCHED		0
@@ -61,6 +62,7 @@ int assign_dsn_attr(esodbc_dsn_attrs_st *attrs,
 		{&MK_WSTR(ESODBC_DSN_DSN), &attrs->dsn},
 		{&MK_WSTR(ESODBC_DSN_PWD), &attrs->pwd},
 		{&MK_WSTR(ESODBC_DSN_UID), &attrs->uid},
+		{&MK_WSTR(ESODBC_DSN_API_KEY), &attrs->api_key},
 		{&MK_WSTR(ESODBC_DSN_SAVEFILE), &attrs->savefile},
 		{&MK_WSTR(ESODBC_DSN_FILEDSN), &attrs->filedsn},
 		{&MK_WSTR(ESODBC_DSN_CLOUD_ID), &attrs->cloud_id},
@@ -404,6 +406,7 @@ long TEST_API write_00_list(esodbc_dsn_attrs_st *attrs,
 		{&MK_WSTR(ESODBC_DSN_DSN), &attrs->dsn},
 		{&MK_WSTR(ESODBC_DSN_PWD), &attrs->pwd},
 		{&MK_WSTR(ESODBC_DSN_UID), &attrs->uid},
+		{&MK_WSTR(ESODBC_DSN_API_KEY), &attrs->api_key},
 		{&MK_WSTR(ESODBC_DSN_SAVEFILE), &attrs->savefile},
 		{&MK_WSTR(ESODBC_DSN_FILEDSN), &attrs->filedsn},
 		{&MK_WSTR(ESODBC_DSN_CLOUD_ID), &attrs->cloud_id},
@@ -637,6 +640,10 @@ BOOL write_system_dsn(esodbc_dsn_attrs_st *new_attrs,
 			&MK_WSTR(ESODBC_DSN_UID), &new_attrs->uid,
 			old_attrs ? &old_attrs->uid : NULL
 		},
+		{
+			&MK_WSTR(ESODBC_DSN_API_KEY), &new_attrs->api_key,
+			old_attrs ? &old_attrs->api_key : NULL
+		},
 		/* SAVEILE */
 		/* FILEDSN */
 		{
@@ -819,6 +826,7 @@ long TEST_API write_connection_string(esodbc_dsn_attrs_st *attrs,
 		{&attrs->dsn, &MK_WSTR(ESODBC_DSN_DSN)},
 		{&attrs->pwd, &MK_WSTR(ESODBC_DSN_PWD)},
 		{&attrs->uid, &MK_WSTR(ESODBC_DSN_UID)},
+		{&attrs->api_key, &MK_WSTR(ESODBC_DSN_API_KEY)},
 		{&attrs->savefile, &MK_WSTR(ESODBC_DSN_SAVEFILE)},
 		{&attrs->filedsn, &MK_WSTR(ESODBC_DSN_FILEDSN)},
 		{&attrs->cloud_id, &MK_WSTR(ESODBC_DSN_CLOUD_ID)},

driver/dsn.h

@@ -20,6 +20,7 @@
 #define ESODBC_DSN_DSN				"DSN"
 #define ESODBC_DSN_PWD				"PWD"
 #define ESODBC_DSN_UID				"UID"
+#define ESODBC_DSN_API_KEY			"APIKey"
 #define ESODBC_DSN_SAVEFILE			"SAVEFILE"
 #define ESODBC_DSN_FILEDSN			"FILEDSN"
 #define ESODBC_DSN_CLOUD_ID			"CloudID"
@@ -71,6 +72,7 @@ typedef struct {
 	wstr_st dsn;
 	wstr_st pwd;
 	wstr_st uid;
+	wstr_st api_key;
 	wstr_st savefile;
 	wstr_st filedsn;
 	wstr_st cloud_id;
@@ -102,7 +104,7 @@ typedef struct {
 	wstr_st trace_enabled;
 	wstr_st trace_file;
 	wstr_st trace_level;
-#define ESODBC_DSN_ATTRS_COUNT	36
+#define ESODBC_DSN_ATTRS_COUNT	37
 
 	SQLWCHAR buff[ESODBC_DSN_ATTRS_COUNT * ESODBC_DSN_MAX_ATTR_LEN];
 	/* DSN reading/writing functions are passed a SQLSMALLINT length param */

driver/handles.h

@@ -150,7 +150,10 @@ typedef struct struct_dbc {
 	cstr_st ca_path;
 
 	cstr_st uid;
-	cstr_st pwd;
+	union {
+		cstr_st pwd; /* when dbc configuring, pwd is only set if uid is */
+		cstr_st api_key;
+	};
 	SQLUINTEGER timeout;
 	BOOL follow;
 	struct {
@@ -204,6 +207,7 @@ typedef struct struct_dbc {
 	size_t apos; /* current write position in the abuff */
 	size_t amax; /* maximum length (bytes) that abuff can grow to */
 	esodbc_mutex_lt curl_mux; /* mutex for above 'networking' members */
+	struct curl_slist *curl_hdrs; /* HTTP headers list */
 
 	/* window handler */
 	HWND hwin;