From ef39868b6bffa3030c7cbc083df1301849fba0f7 Mon Sep 17 00:00:00 2001
From: Jesper Jensen <jesper@slashwin.dk>
Date: Sat, 16 Oct 2021 20:16:38 +0200
Subject: Add find_node query

---
 src/query.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 99 insertions(+), 2 deletions(-)

(limited to 'src/query.c')

diff --git a/src/query.c b/src/query.c
index 806c691..6012540 100644
--- a/src/query.c
+++ b/src/query.c
@@ -4,6 +4,7 @@
 
 #include <string.h>
 #include <errno.h>
+#include <assert.h>
 
 int handle_request(struct nodeid* self, const char* method, const char* packet, size_t packet_len, char** response, size_t response_len) {
 	if(strcmp(method, "ping") == 0) {
@@ -71,11 +72,107 @@ int handle_request(struct nodeid* self, const char* method, const char* packet,
 		*response += rc;
 		memcpy(*response, self, sizeof(struct nodeid));
 		*response += sizeof(struct nodeid);
-		rc = snprintf(*response, end-*response, "ee");
+		rc = snprintf(*response, end-*response, "e");
 		if(rc < 0)
 			return QUERY_EBADQ;
 		*response += rc;
-	}else if(strcmp(method, "get_peers") == 0) {
+	} else if(strcmp(method, "find_node") == 0) {
+		struct bcursor bcursor;
+		struct benc_node stream[256];
+		bcur_open(&bcursor, packet, packet+packet_len, stream, 256);
+
+		if(bcursor.readhead->type != BNT_DICT) {
+			err("Bad query: Packet is not a dict");
+			return QUERY_EBADQ;
+		}
+		if(bcur_next(&bcursor, 1) < 0) {
+			err("Bad query: No token after outer dict start");
+			return QUERY_EBADQ;
+		}
+
+		if(bcur_find_key(&bcursor, (const enum benc_nodetype[]){BNT_STRING}, (const char*[]){"a"}, (const size_t[]){1}, 1) != 0) {
+			err("Bad query: No arguments to request");
+			return QUERY_EBADQ;
+		}
+		bcur_next(&bcursor, 1);
+		if(bcursor.readhead->type != BNT_DICT) {
+			err("Bad query: Wrong value type for request");
+			return QUERY_EBADQ;
+		}
+		// Skip the dict element
+		bcur_next(&bcursor, 1);
+		bool target_set = false;
+		struct nodeid target;
+		while(bcursor.readhead->type != BNT_END) {
+			switch(bcur_find_key(&bcursor, (const enum benc_nodetype[]){BNT_STRING}, (const char*[]){"target"}, (const size_t[]){6}, 1)) {
+				case 0:
+					// Skip the key
+					bcur_next(&bcursor, 1);
+
+					if(bcursor.readhead->type != BNT_STRING) {
+						err("Bad query: Wrong value type for id");
+						return QUERY_EBADQ;
+					}
+
+					if(bcursor.readhead->size != 20) {
+						err("Bad query: Incorrect target length");
+						return QUERY_EBADQ;
+					}
+
+					target_set = true;
+					memcpy(&target, bcursor.readhead->loc, 20);
+
+					// Skip the value
+					bcur_next(&bcursor, 1);
+					break;
+			}
+		}
+
+		if(!target_set) {
+			err("Target argument not set");
+			return QUERY_EBADQ;
+		}
+
+		// Actually do the handling
+		struct entry* closest[8];
+		int found = routing_closest(&target, 8, closest);
+
+		char* end = (*response) + response_len;
+
+		int rc = snprintf(*response, end-*response, "d2:id20:");
+		if(rc < 0)
+			return QUERY_EBADQ;
+		*response += rc;
+		assert(*response < end);
+
+		memcpy(*response, self, sizeof(struct nodeid));
+		*response += sizeof(struct nodeid);
+		assert(*response < end);
+
+		rc = snprintf(*response, end-*response, "5:nodes%d:", found*26);
+		if(rc < 0)
+			return QUERY_EBADQ;
+		*response += rc;
+		assert(*response < end);
+
+		for(int i = 0; i < found; i++) {
+			memcpy(*response, &closest[i]->id, sizeof(struct nodeid));
+			*response += sizeof(struct nodeid); // 20
+			assert(*response < end);
+			memcpy(*response, &closest[i]->addr.ip, sizeof(uint32_t));
+			*response += sizeof(uint32_t); // 4
+			assert(*response < end);
+			memcpy(*response, &closest[i]->addr.port, sizeof(uint16_t));
+			*response += sizeof(uint16_t); // 2
+			assert(*response < end);
+		}
+
+		rc = snprintf(*response, end-*response, "e");
+		if(rc < 0)
+			return QUERY_EBADQ;
+		*response += rc;
+		assert(*response < end);
+	} else if(strcmp(method, "get_peers") == 0) {
 	} else {
 		return QUERY_EUNK;
 	}
-- 
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