Refactor channel binding code to fetch cbind_data only when necessary

As things stand now, channel binding data is fetched from OpenSSL and
saved into the SCRAM exchange context for any SSL connection attempted
for a SCRAM authentication, resulting in data fetched but not used if no
channel binding is used or if a different channel binding type is used
than what the data is here for.

Refactor the code in such a way that binding data is fetched from the
SSL stack only when a specific channel binding is used for both the
frontend and the backend.  In order to achieve that, save the libpq
connection context directly in the SCRAM exchange state, and add a
dependency to SSL in the low-level SCRAM routines.

This makes the interface in charge of initializing the SCRAM context
cleaner as all its data comes from either PGconn* (for frontend) or
Port* (for the backend).

Author: Michael Paquier <michael.paquier@gmail.com>

src/backend/libpq/auth-scram.c

@@ -110,10 +110,8 @@ typedef struct
 
 	const char *username;		/* username from startup packet */
 
+	Port	   *port;
 	char		cbind_flag;
-	bool		ssl_in_use;
-	const char *tls_finished_message;
-	size_t		tls_finished_len;
 	char	   *channel_binding_type;
 
 	int			iterations;
@@ -172,21 +170,15 @@ static char *scram_mock_salt(const char *username);
  * it will fail, as if an incorrect password was given.
  */
 void *
-pg_be_scram_init(const char *username,
-				 const char *shadow_pass,
-				 bool ssl_in_use,
-				 const char *tls_finished_message,
-				 size_t tls_finished_len)
+pg_be_scram_init(Port *port,
+				 const char *shadow_pass)
 {
 	scram_state *state;
 	bool		got_verifier;
 
 	state = (scram_state *) palloc0(sizeof(scram_state));
+	state->port = port;
 	state->state = SCRAM_AUTH_INIT;
-	state->username = username;
-	state->ssl_in_use = ssl_in_use;
-	state->tls_finished_message = tls_finished_message;
-	state->tls_finished_len = tls_finished_len;
 	state->channel_binding_type = NULL;
 
 	/*
@@ -209,7 +201,7 @@ pg_be_scram_init(const char *username,
 				 */
 				ereport(LOG,
 						(errmsg("invalid SCRAM verifier for user \"%s\"",
-								username)));
+								state->port->user_name)));
 				got_verifier = false;
 			}
 		}
@@ -220,7 +212,7 @@ pg_be_scram_init(const char *username,
 			 * authentication with an MD5 hash.)
 			 */
 			state->logdetail = psprintf(_("User \"%s\" does not have a valid SCRAM verifier."),
-										state->username);
+										state->port->user_name);
 			got_verifier = false;
 		}
 	}
@@ -242,8 +234,8 @@ pg_be_scram_init(const char *username,
 	 */
 	if (!got_verifier)
 	{
-		mock_scram_verifier(username, &state->iterations, &state->salt,
-							state->StoredKey, state->ServerKey);
+		mock_scram_verifier(state->port->user_name, &state->iterations,
+							&state->salt, state->StoredKey, state->ServerKey);
 		state->doomed = true;
 	}
 
@@ -815,7 +807,7 @@ read_client_first_message(scram_state *state, char *input)
 			 * it supports channel binding, which in this implementation is
 			 * the case if a connection is using SSL.
 			 */
-			if (state->ssl_in_use)
+			if (state->port->ssl_in_use)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 						 errmsg("SCRAM channel binding negotiation error"),
@@ -839,7 +831,7 @@ read_client_first_message(scram_state *state, char *input)
 			{
 				char	   *channel_binding_type;
 
-				if (!state->ssl_in_use)
+				if (!state->port->ssl_in_use)
 				{
 					/*
 					 * Without SSL, we don't support channel binding.
@@ -1120,8 +1112,9 @@ read_client_final_message(scram_state *state, char *input)
 		 */
 		if (strcmp(state->channel_binding_type, SCRAM_CHANNEL_BINDING_TLS_UNIQUE) == 0)
 		{
-			cbind_data = state->tls_finished_message;
-			cbind_data_len = state->tls_finished_len;
+#ifdef USE_SSL
+			cbind_data = be_tls_get_peer_finished(state->port, &cbind_data_len);
+#endif
 		}
 		else
 		{

src/backend/libpq/auth.c

@@ -873,8 +873,6 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 	int			inputlen;
 	int			result;
 	bool		initial;
-	char	   *tls_finished = NULL;
-	size_t		tls_finished_len = 0;
 
 	/*
 	 * SASL auth is not supported for protocol versions before 3, because it
@@ -915,17 +913,6 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 	sendAuthRequest(port, AUTH_REQ_SASL, sasl_mechs, p - sasl_mechs + 1);
 	pfree(sasl_mechs);
 
-#ifdef USE_SSL
-
-	/*
-	 * Get data for channel binding.
-	 */
-	if (port->ssl_in_use)
-	{
-		tls_finished = be_tls_get_peer_finished(port, &tls_finished_len);
-	}
-#endif
-
 	/*
 	 * Initialize the status tracker for message exchanges.
 	 *
@@ -937,11 +924,7 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 	 * This is because we don't want to reveal to an attacker what usernames
 	 * are valid, nor which users have a valid password.
 	 */
-	scram_opaq = pg_be_scram_init(port->user_name,
-								  shadow_pass,
-								  port->ssl_in_use,
-								  tls_finished,
-								  tls_finished_len);
+	scram_opaq = pg_be_scram_init(port, shadow_pass);
 
 	/*
 	 * Loop through SASL message exchange.  This exchange can consist of

src/include/libpq/scram.h

@@ -13,15 +13,15 @@
 #ifndef PG_SCRAM_H
 #define PG_SCRAM_H
 
+#include "libpq/libpq-be.h"
+
 /* Status codes for message exchange */
 #define SASL_EXCHANGE_CONTINUE		0
 #define SASL_EXCHANGE_SUCCESS		1
 #define SASL_EXCHANGE_FAILURE		2
 
 /* Routines dedicated to authentication */
-extern void *pg_be_scram_init(const char *username, const char *shadow_pass,
-				 bool ssl_in_use, const char *tls_finished_message,
-				 size_t tls_finished_len);
+extern void *pg_be_scram_init(Port *port, const char *shadow_pass);
 extern int pg_be_scram_exchange(void *opaq, char *input, int inputlen,
 					 char **output, int *outputlen, char **logdetail);
 

src/interfaces/libpq/fe-auth-scram.c

@@ -42,13 +42,9 @@ typedef struct
 	fe_scram_state_enum state;
 
 	/* These are supplied by the user */
-	const char *username;
+	PGconn	   *conn;
 	char	   *password;
-	bool		ssl_in_use;
-	char	   *tls_finished_message;
-	size_t		tls_finished_len;
 	char	   *sasl_mechanism;
-	const char *channel_binding_type;
 
 	/* We construct these */
 	uint8		SaltedPassword[SCRAM_KEY_LEN];
@@ -68,14 +64,10 @@ typedef struct
 	char		ServerSignature[SCRAM_KEY_LEN];
 } fe_scram_state;
 
-static bool read_server_first_message(fe_scram_state *state, char *input,
-						  PQExpBuffer errormessage);
-static bool read_server_final_message(fe_scram_state *state, char *input,
-						  PQExpBuffer errormessage);
-static char *build_client_first_message(fe_scram_state *state,
-						   PQExpBuffer errormessage);
-static char *build_client_final_message(fe_scram_state *state,
-						   PQExpBuffer errormessage);
+static bool read_server_first_message(fe_scram_state *state, char *input);
+static bool read_server_final_message(fe_scram_state *state, char *input);
+static char *build_client_first_message(fe_scram_state *state);
+static char *build_client_final_message(fe_scram_state *state);
 static bool verify_server_signature(fe_scram_state *state);
 static void calculate_client_proof(fe_scram_state *state,
 					   const char *client_final_message_without_proof,
@@ -84,18 +76,11 @@ static bool pg_frontend_random(char *dst, int len);
 
 /*
  * Initialize SCRAM exchange status.
- *
- * The non-const char* arguments should be passed in malloc'ed.  They will be
- * freed by pg_fe_scram_free().
  */
 void *
-pg_fe_scram_init(const char *username,
+pg_fe_scram_init(PGconn *conn,
 				 const char *password,
-				 bool ssl_in_use,
-				 const char *sasl_mechanism,
-				 const char *channel_binding_type,
-				 char *tls_finished_message,
-				 size_t tls_finished_len)
+				 const char *sasl_mechanism)
 {
 	fe_scram_state *state;
 	char	   *prep_password;
@@ -107,13 +92,9 @@ pg_fe_scram_init(const char *username,
 	if (!state)
 		return NULL;
 	memset(state, 0, sizeof(fe_scram_state));
+	state->conn = conn;
 	state->state = FE_SCRAM_INIT;
-	state->username = username;
-	state->ssl_in_use = ssl_in_use;
-	state->tls_finished_message = tls_finished_message;
-	state->tls_finished_len = tls_finished_len;
 	state->sasl_mechanism = strdup(sasl_mechanism);
-	state->channel_binding_type = channel_binding_type;
 
 	if (!state->sasl_mechanism)
 	{
@@ -154,8 +135,6 @@ pg_fe_scram_free(void *opaq)
 
 	if (state->password)
 		free(state->password);
-	if (state->tls_finished_message)
-		free(state->tls_finished_message);
 	if (state->sasl_mechanism)
 		free(state->sasl_mechanism);
 
@@ -188,9 +167,10 @@ pg_fe_scram_free(void *opaq)
 void
 pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 					 char **output, int *outputlen,
-					 bool *done, bool *success, PQExpBuffer errorMessage)
+					 bool *done, bool *success)
 {
 	fe_scram_state *state = (fe_scram_state *) opaq;
+	PGconn	   *conn = state->conn;
 
 	*done = false;
 	*success = false;
@@ -205,13 +185,13 @@ pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 	{
 		if (inputlen == 0)
 		{
-			printfPQExpBuffer(errorMessage,
+			printfPQExpBuffer(&conn->errorMessage,
 							  libpq_gettext("malformed SCRAM message (empty message)\n"));
 			goto error;
 		}
 		if (inputlen != strlen(input))
 		{
-			printfPQExpBuffer(errorMessage,
+			printfPQExpBuffer(&conn->errorMessage,
 							  libpq_gettext("malformed SCRAM message (length mismatch)\n"));
 			goto error;
 		}
@@ -221,7 +201,7 @@ pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 	{
 		case FE_SCRAM_INIT:
 			/* Begin the SCRAM handshake, by sending client nonce */
-			*output = build_client_first_message(state, errorMessage);
+			*output = build_client_first_message(state);
 			if (*output == NULL)
 				goto error;
 
@@ -232,10 +212,10 @@ pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 
 		case FE_SCRAM_NONCE_SENT:
 			/* Receive salt and server nonce, send response. */
-			if (!read_server_first_message(state, input, errorMessage))
+			if (!read_server_first_message(state, input))
 				goto error;
 
-			*output = build_client_final_message(state, errorMessage);
+			*output = build_client_final_message(state);
 			if (*output == NULL)
 				goto error;
 
@@ -246,7 +226,7 @@ pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 
 		case FE_SCRAM_PROOF_SENT:
 			/* Receive server signature */
-			if (!read_server_final_message(state, input, errorMessage))
+			if (!read_server_final_message(state, input))
 				goto error;
 
 			/*
@@ -260,7 +240,7 @@ pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 			else
 			{
 				*success = false;
-				printfPQExpBuffer(errorMessage,
+				printfPQExpBuffer(&conn->errorMessage,
 								  libpq_gettext("incorrect server signature\n"));
 			}
 			*done = true;
@@ -269,7 +249,7 @@ pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 
 		default:
 			/* shouldn't happen */
-			printfPQExpBuffer(errorMessage,
+			printfPQExpBuffer(&conn->errorMessage,
 							  libpq_gettext("invalid SCRAM exchange state\n"));
 			goto error;
 	}
@@ -327,8 +307,9 @@ read_attr_value(char **input, char attr, PQExpBuffer errorMessage)
  * Build the first exchange message sent by the client.
  */
 static char *
-build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
+build_client_first_message(fe_scram_state *state)
 {
+	PGconn	   *conn = state->conn;
 	char		raw_nonce[SCRAM_RAW_NONCE_LEN + 1];
 	char	   *result;
 	int			channel_info_len;
@@ -341,7 +322,7 @@ build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
 	 */
 	if (!pg_frontend_random(raw_nonce, SCRAM_RAW_NONCE_LEN))
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("could not generate nonce\n"));
 		return NULL;
 	}
@@ -349,7 +330,7 @@ build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
 	state->client_nonce = malloc(pg_b64_enc_len(SCRAM_RAW_NONCE_LEN) + 1);
 	if (state->client_nonce == NULL)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("out of memory\n"));
 		return NULL;
 	}
@@ -370,11 +351,11 @@ build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
 	 */
 	if (strcmp(state->sasl_mechanism, SCRAM_SHA256_PLUS_NAME) == 0)
 	{
-		Assert(state->ssl_in_use);
-		appendPQExpBuffer(&buf, "p=%s", state->channel_binding_type);
+		Assert(conn->ssl_in_use);
+		appendPQExpBuffer(&buf, "p=%s", conn->scram_channel_binding);
 	}
-	else if (state->channel_binding_type == NULL ||
-			 strlen(state->channel_binding_type) == 0)
+	else if (conn->scram_channel_binding == NULL ||
+			 strlen(conn->scram_channel_binding) == 0)
 	{
 		/*
 		 * Client has chosen to not show to server that it supports channel
@@ -382,7 +363,7 @@ build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
 		 */
 		appendPQExpBuffer(&buf, "n");
 	}
-	else if (state->ssl_in_use)
+	else if (conn->ssl_in_use)
 	{
 		/*
 		 * Client supports channel binding, but thinks the server does not.
@@ -423,7 +404,7 @@ build_client_first_message(fe_scram_state *state, PQExpBuffer errormessage)
 
 oom_error:
 	termPQExpBuffer(&buf);
-	printfPQExpBuffer(errormessage,
+	printfPQExpBuffer(&conn->errorMessage,
 					  libpq_gettext("out of memory\n"));
 	return NULL;
 }
@@ -432,9 +413,10 @@ oom_error:
  * Build the final exchange message sent from the client.
  */
 static char *
-build_client_final_message(fe_scram_state *state, PQExpBuffer errormessage)
+build_client_final_message(fe_scram_state *state)
 {
 	PQExpBufferData buf;
+	PGconn	   *conn = state->conn;
 	uint8		client_proof[SCRAM_KEY_LEN];
 	char	   *result;
 
@@ -450,22 +432,25 @@ build_client_final_message(fe_scram_state *state, PQExpBuffer errormessage)
 	 */
 	if (strcmp(state->sasl_mechanism, SCRAM_SHA256_PLUS_NAME) == 0)
 	{
-		char	   *cbind_data;
-		size_t		cbind_data_len;
+		char	   *cbind_data = NULL;
+		size_t		cbind_data_len = 0;
 		size_t		cbind_header_len;
 		char	   *cbind_input;
 		size_t		cbind_input_len;
 
-		if (strcmp(state->channel_binding_type, SCRAM_CHANNEL_BINDING_TLS_UNIQUE) == 0)
+		if (strcmp(conn->scram_channel_binding, SCRAM_CHANNEL_BINDING_TLS_UNIQUE) == 0)
 		{
-			cbind_data = state->tls_finished_message;
-			cbind_data_len = state->tls_finished_len;
+#ifdef USE_SSL
+			cbind_data = pgtls_get_finished(state->conn, &cbind_data_len);
+			if (cbind_data == NULL)
+				goto oom_error;
+#endif
 		}
 		else
 		{
 			/* should not happen */
 			termPQExpBuffer(&buf);
-			printfPQExpBuffer(errormessage,
+			printfPQExpBuffer(&conn->errorMessage,
 							  libpq_gettext("invalid channel binding type\n"));
 			return NULL;
 		}
@@ -473,37 +458,46 @@ build_client_final_message(fe_scram_state *state, PQExpBuffer errormessage)
 		/* should not happen */
 		if (cbind_data == NULL || cbind_data_len == 0)
 		{
+			if (cbind_data != NULL)
+				free(cbind_data);
 			termPQExpBuffer(&buf);
-			printfPQExpBuffer(errormessage,
+			printfPQExpBuffer(&conn->errorMessage,
 							  libpq_gettext("empty channel binding data for channel binding type \"%s\"\n"),
-							  state->channel_binding_type);
+							  conn->scram_channel_binding);
 			return NULL;
 		}
 
 		appendPQExpBuffer(&buf, "c=");
 
-		cbind_header_len = 4 + strlen(state->channel_binding_type); /* p=type,, */
+		/* p=type,, */
+		cbind_header_len = 4 + strlen(conn->scram_channel_binding);
 		cbind_input_len = cbind_header_len + cbind_data_len;
 		cbind_input = malloc(cbind_input_len);
 		if (!cbind_input)
+		{
+			free(cbind_data);
 			goto oom_error;
-		snprintf(cbind_input, cbind_input_len, "p=%s,,", state->channel_binding_type);
+		}
+		snprintf(cbind_input, cbind_input_len, "p=%s,,",
+				 conn->scram_channel_binding);
 		memcpy(cbind_input + cbind_header_len, cbind_data, cbind_data_len);
 
 		if (!enlargePQExpBuffer(&buf, pg_b64_enc_len(cbind_input_len)))
 		{
+			free(cbind_data);
 			free(cbind_input);
 			goto oom_error;
 		}
 		buf.len += pg_b64_encode(cbind_input, cbind_input_len, buf.data + buf.len);
 		buf.data[buf.len] = '\0';
 
+		free(cbind_data);
 		free(cbind_input);
 	}
-	else if (state->channel_binding_type == NULL ||
-			 strlen(state->channel_binding_type) == 0)
+	else if (conn->scram_channel_binding == NULL ||
+			 strlen(conn->scram_channel_binding) == 0)
 		appendPQExpBuffer(&buf, "c=biws");	/* base64 of "n,," */
-	else if (state->ssl_in_use)
+	else if (conn->ssl_in_use)
 		appendPQExpBuffer(&buf, "c=eSws");	/* base64 of "y,," */
 	else
 		appendPQExpBuffer(&buf, "c=biws");	/* base64 of "n,," */
@@ -541,7 +535,7 @@ build_client_final_message(fe_scram_state *state, PQExpBuffer errormessage)
 
 oom_error:
 	termPQExpBuffer(&buf);
-	printfPQExpBuffer(errormessage,
+	printfPQExpBuffer(&conn->errorMessage,
 					  libpq_gettext("out of memory\n"));
 	return NULL;
 }
@@ -550,9 +544,9 @@ oom_error:
  * Read the first exchange message coming from the server.
  */
 static bool
-read_server_first_message(fe_scram_state *state, char *input,
-						  PQExpBuffer errormessage)
+read_server_first_message(fe_scram_state *state, char *input)
 {
+	PGconn	   *conn = state->conn;
 	char	   *iterations_str;
 	char	   *endptr;
 	char	   *encoded_salt;
@@ -561,13 +555,14 @@ read_server_first_message(fe_scram_state *state, char *input,
 	state->server_first_message = strdup(input);
 	if (state->server_first_message == NULL)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("out of memory\n"));
 		return false;
 	}
 
 	/* parse the message */
-	nonce = read_attr_value(&input, 'r', errormessage);
+	nonce = read_attr_value(&input, 'r',
+							&conn->errorMessage);
 	if (nonce == NULL)
 	{
 		/* read_attr_value() has generated an error string */
@@ -578,7 +573,7 @@ read_server_first_message(fe_scram_state *state, char *input,
 	if (strlen(nonce) < strlen(state->client_nonce) ||
 		memcmp(nonce, state->client_nonce, strlen(state->client_nonce)) != 0)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("invalid SCRAM response (nonce mismatch)\n"));
 		return false;
 	}
@@ -586,12 +581,12 @@ read_server_first_message(fe_scram_state *state, char *input,
 	state->nonce = strdup(nonce);
 	if (state->nonce == NULL)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("out of memory\n"));
 		return false;
 	}
 
-	encoded_salt = read_attr_value(&input, 's', errormessage);
+	encoded_salt = read_attr_value(&input, 's', &conn->errorMessage);
 	if (encoded_salt == NULL)
 	{
 		/* read_attr_value() has generated an error string */
@@ -600,7 +595,7 @@ read_server_first_message(fe_scram_state *state, char *input,
 	state->salt = malloc(pg_b64_dec_len(strlen(encoded_salt)));
 	if (state->salt == NULL)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("out of memory\n"));
 		return false;
 	}
@@ -608,7 +603,7 @@ read_server_first_message(fe_scram_state *state, char *input,
 								   strlen(encoded_salt),
 								   state->salt);
 
-	iterations_str = read_attr_value(&input, 'i', errormessage);
+	iterations_str = read_attr_value(&input, 'i', &conn->errorMessage);
 	if (iterations_str == NULL)
 	{
 		/* read_attr_value() has generated an error string */
@@ -617,13 +612,13 @@ read_server_first_message(fe_scram_state *state, char *input,
 	state->iterations = strtol(iterations_str, &endptr, 10);
 	if (*endptr != '\0' || state->iterations < 1)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("malformed SCRAM message (invalid iteration count)\n"));
 		return false;
 	}
 
 	if (*input != '\0')
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("malformed SCRAM message (garbage at end of server-first-message)\n"));
 
 	return true;
@@ -633,16 +628,16 @@ read_server_first_message(fe_scram_state *state, char *input,
  * Read the final exchange message coming from the server.
  */
 static bool
-read_server_final_message(fe_scram_state *state, char *input,
-						  PQExpBuffer errormessage)
+read_server_final_message(fe_scram_state *state, char *input)
 {
+	PGconn	   *conn = state->conn;
 	char	   *encoded_server_signature;
 	int			server_signature_len;
 
 	state->server_final_message = strdup(input);
 	if (!state->server_final_message)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("out of memory\n"));
 		return false;
 	}
@@ -650,16 +645,18 @@ read_server_final_message(fe_scram_state *state, char *input,
 	/* Check for error result. */
 	if (*input == 'e')
 	{
-		char	   *errmsg = read_attr_value(&input, 'e', errormessage);
+		char	   *errmsg = read_attr_value(&input, 'e',
+											 &conn->errorMessage);
 
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("error received from server in SCRAM exchange: %s\n"),
 						  errmsg);
 		return false;
 	}
 
 	/* Parse the message. */
-	encoded_server_signature = read_attr_value(&input, 'v', errormessage);
+	encoded_server_signature = read_attr_value(&input, 'v',
+											   &conn->errorMessage);
 	if (encoded_server_signature == NULL)
 	{
 		/* read_attr_value() has generated an error message */
@@ -667,7 +664,7 @@ read_server_final_message(fe_scram_state *state, char *input,
 	}
 
 	if (*input != '\0')
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("malformed SCRAM message (garbage at end of server-final-message)\n"));
 
 	server_signature_len = pg_b64_decode(encoded_server_signature,
@@ -675,7 +672,7 @@ read_server_final_message(fe_scram_state *state, char *input,
 										 state->ServerSignature);
 	if (server_signature_len != SCRAM_KEY_LEN)
 	{
-		printfPQExpBuffer(errormessage,
+		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("malformed SCRAM message (invalid server signature)\n"));
 		return false;
 	}

src/interfaces/libpq/fe-auth.c

@@ -491,8 +491,6 @@ pg_SASL_init(PGconn *conn, int payloadlen)
 	bool		success;
 	const char *selected_mechanism;
 	PQExpBufferData mechanism_buf;
-	char	   *tls_finished = NULL;
-	size_t		tls_finished_len = 0;
 	char	   *password;
 
 	initPQExpBuffer(&mechanism_buf);
@@ -570,32 +568,15 @@ pg_SASL_init(PGconn *conn, int payloadlen)
 		goto error;
 	}
 
-#ifdef USE_SSL
-
-	/*
-	 * Get data for channel binding.
-	 */
-	if (strcmp(selected_mechanism, SCRAM_SHA256_PLUS_NAME) == 0)
-	{
-		tls_finished = pgtls_get_finished(conn, &tls_finished_len);
-		if (tls_finished == NULL)
-			goto oom_error;
-	}
-#endif
-
 	/*
 	 * Initialize the SASL state information with all the information gathered
 	 * during the initial exchange.
 	 *
 	 * Note: Only tls-unique is supported for the moment.
 	 */
-	conn->sasl_state = pg_fe_scram_init(conn->pguser,
+	conn->sasl_state = pg_fe_scram_init(conn,
 										password,
-										conn->ssl_in_use,
-										selected_mechanism,
-										conn->scram_channel_binding,
-										tls_finished,
-										tls_finished_len);
+										selected_mechanism);
 	if (!conn->sasl_state)
 		goto oom_error;
 
@@ -603,7 +584,7 @@ pg_SASL_init(PGconn *conn, int payloadlen)
 	pg_fe_scram_exchange(conn->sasl_state,
 						 NULL, -1,
 						 &initialresponse, &initialresponselen,
-						 &done, &success, &conn->errorMessage);
+						 &done, &success);
 
 	if (done && !success)
 		goto error;
@@ -684,7 +665,7 @@ pg_SASL_continue(PGconn *conn, int payloadlen, bool final)
 	pg_fe_scram_exchange(conn->sasl_state,
 						 challenge, payloadlen,
 						 &output, &outputlen,
-						 &done, &success, &conn->errorMessage);
+						 &done, &success);
 	free(challenge);			/* don't need the input anymore */
 
 	if (final && !done)

src/interfaces/libpq/fe-auth.h

@@ -23,17 +23,13 @@ extern int	pg_fe_sendauth(AuthRequest areq, int payloadlen, PGconn *conn);
 extern char *pg_fe_getauthname(PQExpBuffer errorMessage);
 
 /* Prototypes for functions in fe-auth-scram.c */
-extern void *pg_fe_scram_init(const char *username,
+extern void *pg_fe_scram_init(PGconn *conn,
 				 const char *password,
-				 bool ssl_in_use,
-				 const char *sasl_mechanism,
-				 const char *channel_binding_type,
-				 char *tls_finished_message,
-				 size_t tls_finished_len);
+				 const char *sasl_mechanism);
 extern void pg_fe_scram_free(void *opaq);
 extern void pg_fe_scram_exchange(void *opaq, char *input, int inputlen,
 					 char **output, int *outputlen,
-					 bool *done, bool *success, PQExpBuffer errorMessage);
+					 bool *done, bool *success);
 extern char *pg_fe_scram_build_verifier(const char *password);
 
 #endif							/* FE_AUTH_H */