1 files changed, 47 insertions, 3 deletions

diff --git a/ssh/client.c b/ssh/client.c
index 64f8f57..80e14a4 100644
--- a/ssh/client.c
+++ b/ssh/client.c
@@ -83,6 +83,38 @@ static void splice_scanned(struct readbuffer *rb) {
 	rb->newline_cursor = 0;
 }
 
+static bool prompt_yn(struct readbuffer *rb, const char *text) {
+	printf("%s [y/n] ", text);
+	fflush(stdout);
+
+	while (true) {
+		struct string_view line = extract_line(rb);
+		if (line.s == NULL) {
+			read_more_data(STDIN_FILENO, rb);
+			continue;
+		}
+
+		splice_scanned(rb);
+
+		if (line.len <= 3) {
+			char buf[4];
+			memcpy(buf, line.s, line.len);
+			buf[line.len] = '\0';
+
+			if (strcmp(buf, "y") == 0 || strcmp(buf, "yes") == 0) {
+				return true;
+			}
+
+			if (strcmp(buf, "n") == 0 || strcmp(buf, "no") == 0) {
+				return false;
+			}
+		}
+
+		printf("Please answer with 'y', 'n', 'yes' or 'no'. [y/n] ");
+		fflush(stdout);
+	}
+}
+
 static struct string_view tokenise_greedy(struct string_view *line) {
 	sv_skip_whitespace(line);
 	return sv_tokenise_word(line);
@@ -415,6 +447,17 @@ static void handle_event(struct state *state, const struct tomsg_event event) {
 	}
 }
 
+static bool hostkey_checker(const unsigned char *hash, size_t length, void *stdinbuf_) {
+	struct readbuffer *stdinbuf = stdinbuf_;
+
+	const char *fingerprint = tomsg_print_hash(hash, length);
+
+	printf("Server host key fingerprint: %s\n", fingerprint);
+	return prompt_yn(stdinbuf,
+		"Does this hash match the one given to you by the server administrator, or by a\n"
+		"member that you trust and is already connected to the server?");
+}
+
 int main(int argc, char **argv) {
 	if (argc != 2) {
 		printf("Usage: %s <hostname:port>\n", argv[0]);
@@ -428,10 +471,13 @@ int main(int argc, char **argv) {
 		return 1;
 	}
 
+	struct readbuffer stdinbuf = readbuffer_new();
+
 	printf("Connecting...\n");
 
 	struct tomsg_client *client;
-	enum tomsg_retval ret = tomsg_connect(hostname, port, &client);
+	enum tomsg_retval ret = tomsg_connect(
+			hostname, port, hostkey_checker, &stdinbuf, &client);
 	if (ret != TOMSG_OK) {
 		printf("Could not connect: %s\n", tomsg_strerror(ret));
 		return 1;
@@ -439,8 +485,6 @@ int main(int argc, char **argv) {
 
 	printf("Connected.\n");
 
-	struct readbuffer stdinbuf = readbuffer_new();
-
 	struct state state = (struct state){
 		.rooms = NULL,
 		.num_rooms = 0,