getroute: remove seed arg, document fromid, make default fuzzpercent match docs.

seed isn't very useful at this level: I've left it in routing.c
because it might be useful for detailed testing.  Pretty sure it's unused,
so I simply removed it.

The fuzzpercent is documented to default at 5%, but actually was 75%.
Fix that too.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

CHANGELOG.md

@@ -109,6 +109,8 @@ changes.
 
 ### Removed
 
+- JSON API: the optional 'seed' parameter to `getroute` was removed.
+
 ### Fixed
 
 - Startup: more coherent complaint if daemon already running.

doc/lightning-getroute.7

@@ -2,12 +2,12 @@
 .\"     Title: lightning-getroute
 .\"    Author: [see the "AUTHOR" section]
 .\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
-.\"      Date: 09/17/2018
+.\"      Date: 12/17/2018
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "LIGHTNING\-GETROUTE" "7" "09/17/2018" "\ \&" "\ \&"
+.TH "LIGHTNING\-GETROUTE" "7" "12/17/2018" "\ \&" "\ \&"
 .\" -----------------------------------------------------------------
 .\" * Define some portability stuff
 .\" -----------------------------------------------------------------
@@ -31,7 +31,7 @@
 lightning-getroute \- Command for routing a payment (low\-level)\&.
 .SH "SYNOPSIS"
 .sp
-\fBgetroute\fR \fIid\fR \fImsatoshi\fR \fIriskfactor\fR [\fIcltv\fR] [\fIfuzzpercent\fR] [\fIseed\fR]
+\fBgetroute\fR \fIid\fR \fImsatoshi\fR \fIriskfactor\fR [\fIcltv\fR] [\fIfromid\fR] [\fIfuzzpercent\fR]
 .SH "DESCRIPTION"
 .sp
 The \fBgetroute\fR RPC command attempts to find the best route for the payment of \fImsatoshi\fR to lightning node \fIid\fR, such that the payment will arrive at \fIid\fR with \fIcltv\fR\-blocks to spare (default 9)\&.
@@ -42,9 +42,9 @@ For example, if you thought there was a 1% chance that a node would fail, and it
 .sp
 If you didn\(cqt care about risk, \fIriskfactor\fR would be zero\&.
 .sp
-The \fIfuzzpercent\fR is a positive floating\-point number, representing a percentage of the actual fee\&. The \fIfuzzpercent\fR is used to distort computed fees along each channel, to provide some randomization to the route generated\&. 0\&.0 means the exact fee of that channel is used, while 100\&.0 means the fee used might be from 0 to twice the actual fee\&. The default is 5\&.0, or up to 5% fee distortion\&.
+\fIfromid\fR is the node to start the route from: default is this node\&.
 .sp
-The \fIseed\fR is a string whose bytes are used to seed the RNG for the route randomization\&. If not specified, a random string is used\&.
+The \fIfuzzpercent\fR is a positive floating\-point number, representing a percentage of the actual fee\&. The \fIfuzzpercent\fR is used to distort computed fees along each channel, to provide some randomization to the route generated\&. 0\&.0 means the exact fee of that channel is used, while 100\&.0 means the fee used might be from 0 to twice the actual fee\&. The default is 5\&.0, or up to 5% fee distortion\&.
 .SH "RISKFACTOR EFFECT ON ROUTING"
 .sp
 The risk factor is treated as if it were an additional fee on the route, for the purposes of comparing routes\&.

doc/lightning-getroute.7.txt

@@ -9,7 +9,7 @@ lightning-getroute - Command for routing a payment (low-level).
 
 SYNOPSIS
 --------
-*getroute* 'id' 'msatoshi' 'riskfactor' ['cltv'] ['fuzzpercent'] ['seed']
+*getroute* 'id' 'msatoshi' 'riskfactor' ['cltv'] ['fromid'] ['fuzzpercent']
 
 DESCRIPTION
 -----------
@@ -29,6 +29,8 @@ fail, and it would cost you 20% per annum if that happened,
 
 If you didn't care about risk, 'riskfactor' would be zero.
 
+'fromid' is the node to start the route from: default is this node.
+
 The 'fuzzpercent' is a positive floating-point number, representing a percentage of the actual fee.
 The 'fuzzpercent' is used to distort computed fees along each channel,
 to provide some randomization to the route generated.
@@ -36,10 +38,6 @@ to provide some randomization to the route generated.
 while 100.0 means the fee used might be from 0 to twice the actual fee.
 The default is 5.0, or up to 5% fee distortion.
 
-The 'seed' is a string whose bytes are used to seed the RNG for
-the route randomization.
-If not specified, a random string is used.
-
 
 RISKFACTOR EFFECT ON ROUTING
 ----------------------------

gossipd/gossip_wire.csv

@@ -32,7 +32,6 @@ gossip_getroute_request,,msatoshi,u64
 gossip_getroute_request,,riskfactor,u16
 gossip_getroute_request,,final_cltv,u32
 gossip_getroute_request,,fuzz,double
-gossip_getroute_request,,seed,struct siphash_seed
 
 gossip_getroute_reply,3106
 gossip_getroute_reply,,num_hops,u16

gossipd/gossipd.c

@@ -1870,7 +1870,6 @@ static struct io_plan *getroute_req(struct io_conn *conn, struct daemon *daemon,
 	u8 *out;
 	struct route_hop *hops;
 	double fuzz;
-	struct siphash_seed seed;
 
 	/* To choose between variations, we need to know how much we're
 	 * sending (eliminates too-small channels, and also effects the fees
@@ -1881,7 +1880,7 @@ static struct io_plan *getroute_req(struct io_conn *conn, struct daemon *daemon,
 	if (!fromwire_gossip_getroute_request(msg,
 					      &source, &destination,
 					      &msatoshi, &riskfactor,
-					      &final_cltv, &fuzz, &seed))
+					      &final_cltv, &fuzz))
 		master_badmsg(WIRE_GOSSIP_GETROUTE_REQUEST, msg);
 
 	status_trace("Trying to find a route from %s to %s for %"PRIu64" msatoshi",
@@ -1891,7 +1890,7 @@ static struct io_plan *getroute_req(struct io_conn *conn, struct daemon *daemon,
 	/* routing.c does all the hard work; can return NULL. */
 	hops = get_route(tmpctx, daemon->rstate, &source, &destination,
 			 msatoshi, riskfactor, final_cltv,
-			 fuzz, &seed);
+			 fuzz, siphash_seed());
 
 	out = towire_gossip_getroute_reply(NULL, hops);
 	daemon_conn_send(daemon->master, take(out));

lightningd/gossip_control.c

@@ -300,7 +300,6 @@ static struct command_result *json_getroute(struct command *cmd,
 	struct lightningd *ld = cmd->ld;
 	struct pubkey *destination;
 	struct pubkey *source;
-	const jsmntok_t *seedtok;
 	u64 *msatoshi;
 	unsigned *cltv;
 	double *riskfactor;
@@ -310,7 +309,6 @@ static struct command_result *json_getroute(struct command *cmd,
 	 * be selected) at the cost of increasing the probability of
 	 * selecting the higher-fee paths. */
 	double *fuzz;
-	struct siphash_seed seed;
 
 	if (!param(cmd, buffer, params,
 		   p_req("id", param_pubkey, &destination),
@@ -318,29 +316,16 @@ static struct command_result *json_getroute(struct command *cmd,
 		   p_req("riskfactor", param_double, &riskfactor),
 		   p_opt_def("cltv", param_number, &cltv, 9),
 		   p_opt_def("fromid", param_pubkey, &source, ld->id),
-		   p_opt("seed", param_tok, &seedtok),
+		   p_opt_def("fuzzpercent", param_percent, &fuzz, 5.0),
-		   p_opt_def("fuzzpercent", param_percent, &fuzz, 75.0),
 		   NULL))
 		return command_param_failed();
 
 	/* Convert from percentage */
 	*fuzz = *fuzz / 100.0;
 
-	if (seedtok) {
-		if (seedtok->end - seedtok->start > sizeof(seed))
-			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
-					    "seed must be < %zu bytes",
-					    sizeof(seed));
-
-		memset(&seed, 0, sizeof(seed));
-		memcpy(&seed, buffer + seedtok->start,
-		       seedtok->end - seedtok->start);
-	} else
-		randombytes_buf(&seed, sizeof(seed));
-
 	u8 *req = towire_gossip_getroute_request(cmd, source, destination,
 						 *msatoshi, *riskfactor * 1000,
-						 *cltv, fuzz, &seed);
+						 *cltv, fuzz);
 	subd_req(ld->gossip, ld->gossip, req, -1, 0, json_getroute_reply, cmd);
 	return command_still_pending(cmd);
 }

lightningd/payalgo.c

@@ -508,7 +508,6 @@ static struct command_result *json_pay_try(struct pay *pay)
 	u8 *req;
 	struct command *cmd = pay->cmd;
 	struct timeabs now = time_now();
-	struct siphash_seed seed;
 	u64 maxoverpayment;
 	u64 overpayment;
 
@@ -534,9 +533,6 @@ static struct command_result *json_pay_try(struct pay *pay)
 	/* Clear route */
 	pay->route = tal_free(pay->route);
 
-	/* Generate random seed */
-	randombytes_buf(&seed, sizeof(seed));
-
 	/* Generate an overpayment, from fuzz * maxfee. */
 	/* Now normally the use of double for money is very bad.
 	 * Note however that a later stage will ensure that
@@ -561,8 +557,7 @@ static struct command_result *json_pay_try(struct pay *pay)
 					     pay->msatoshi + overpayment,
 					     pay->riskfactor,
 					     pay->min_final_cltv_expiry,
-					     &pay->fuzz,
+					     &pay->fuzz);
-					     &seed);
 	subd_req(pay->try_parent, cmd->ld->gossip, req, -1, 0, json_pay_getroute_reply, pay);
 
 	return NULL;