1 files changed, 159 insertions, 0 deletions
diff --git a/bouncer/dns.cpp b/bouncer/dns.cpp
new file mode 100644
index 0000000..056bb09
--- /dev/null
+++ b/bouncer/dns.cpp
@@ -0,0 +1,159 @@
+#include "dns.h"
+#include <pthread.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+
+#define DNS_QUERY_COUNT 20
+#define DNS_QUERY_NAME_SIZE 256
+
+enum DNSQueryState {
+	DQS_FREE = 0,
+	DQS_WAITING = 1,
+	DQS_COMPLETE = 2,
+	DQS_ERROR = 3
+};
+
+struct DNSQuery {
+	char name[DNS_QUERY_NAME_SIZE];
+	in_addr result;
+	DNSQueryState status;
+	int version;
+};
+
+static DNSQuery dnsQueue[DNS_QUERY_COUNT];
+static pthread_t dnsThread;
+static pthread_mutex_t dnsQueueMutex;
+static pthread_cond_t dnsQueueCond;
+
+static void *dnsThreadProc(void *);
+
+
+void DNS::start() {
+	pthread_mutex_init(&dnsQueueMutex, NULL);
+	pthread_cond_init(&dnsQueueCond, NULL);
+
+	pthread_create(&dnsThread, NULL, &dnsThreadProc, NULL);
+
+	for (int i = 0; i < DNS_QUERY_COUNT; i++) {
+		dnsQueue[i].status = DQS_FREE;
+		dnsQueue[i].version = 0;
+	}
+}
+
+int DNS::makeQuery(const char *name) {
+	int id = -1;
+
+	pthread_mutex_lock(&dnsQueueMutex);
+
+	for (int i = 0; i < DNS_QUERY_COUNT; i++) {
+		if (dnsQueue[i].status == DQS_FREE) {
+			id = i;
+			break;
+		}
+	}
+
+	if (id != -1) {
+		strncpy(dnsQueue[id].name, name, sizeof(dnsQueue[id].name));
+		dnsQueue[id].name[sizeof(dnsQueue[id].name) - 1] = 0;
+		dnsQueue[id].status = DQS_WAITING;
+		dnsQueue[id].version++;
+		printf("[DNS::%d] New query: %s\n", id, dnsQueue[id].name);
+	}
+
+	pthread_mutex_unlock(&dnsQueueMutex);
+	pthread_cond_signal(&dnsQueueCond);
+
+	return id;
+}
+
+void DNS::closeQuery(int id) {
+	if (id < 0 || id >= DNS_QUERY_COUNT)
+		return;
+
+	pthread_mutex_lock(&dnsQueueMutex);
+	printf("[DNS::%d] Closing query\n", id);
+	dnsQueue[id].status = DQS_FREE;
+	pthread_mutex_unlock(&dnsQueueMutex);
+}
+
+bool DNS::checkQuery(int id, in_addr *pResult, bool *pIsError) {
+	if (id < 0 || id >= DNS_QUERY_COUNT)
+		return false;
+
+	pthread_mutex_lock(&dnsQueueMutex);
+
+	bool finalResult = false;
+	if (dnsQueue[id].status == DQS_COMPLETE) {
+		finalResult = true;
+		*pIsError = false;
+		memcpy(pResult, &dnsQueue[id].result, sizeof(dnsQueue[id].result));
+	} else if (dnsQueue[id].status == DQS_ERROR) {
+		finalResult = true;
+		*pIsError = true;
+	}
+
+	pthread_mutex_unlock(&dnsQueueMutex);
+
+	return finalResult;
+}
+
+
+void *dnsThreadProc(void *) {
+	pthread_mutex_lock(&dnsQueueMutex);
+
+	for (;;) {
+		for (int i = 0; i < DNS_QUERY_COUNT; i++) {
+			if (dnsQueue[i].status == DQS_WAITING) {
+				char nameCopy[DNS_QUERY_NAME_SIZE];
+				memcpy(nameCopy, dnsQueue[i].name, DNS_QUERY_NAME_SIZE);
+
+				int versionCopy = dnsQueue[i].version;
+
+				printf("[DNS::%d] Trying %s...\n", i, nameCopy);
+
+				pthread_mutex_unlock(&dnsQueueMutex);
+
+				addrinfo hints, *res;
+
+				memset(&hints, 0, sizeof(hints));
+				hints.ai_family = AF_INET;
+				hints.ai_socktype = SOCK_STREAM;
+				hints.ai_protocol = IPPROTO_TCP;
+				hints.ai_flags = AI_ADDRCONFIG | AI_V4MAPPED;
+
+				int s = getaddrinfo(nameCopy, NULL, &hints, &res);
+
+				pthread_mutex_lock(&dnsQueueMutex);
+
+				// Before we write to the request, check that it hasn't been
+				// closed (and possibly replaced...!) by another thread
+
+				if (dnsQueue[i].status == DQS_WAITING && dnsQueue[i].version == versionCopy) {
+					if (s == 0) {
+						// Only try the first one for now...
+						// Is this safe? Not sure.
+						dnsQueue[i].status = DQS_COMPLETE;
+						memcpy(&dnsQueue[i].result, &((sockaddr_in*)res->ai_addr)->sin_addr, sizeof(dnsQueue[i].result));
+
+						printf("[DNS::%d] Resolved %s to %x\n", i, dnsQueue[i].name, dnsQueue[i].result.s_addr);
+					} else {
+						dnsQueue[i].status = DQS_ERROR;
+						printf("[DNS::%d] Error condition: %d\n", i, s);
+					}
+				} else {
+					printf("[DNS::%d] Request was cancelled before getaddrinfo completed\n", i);
+				}
+
+				if (s == 0)
+					freeaddrinfo(res);
+			}
+		}
+
+		pthread_cond_wait(&dnsQueueCond, &dnsQueueMutex);
+	}
+
+	pthread_mutex_unlock(&dnsQueueMutex);
+	return NULL;
+}
+