Support multiple simultaneous clients

* replace cqb with a dns request buffer with separate queues for each cnx id
* ensure we respond to the addr from the DNS request we popped from queue

src/slipstream_utils.c

@@ -0,0 +1,44 @@
+#include "slipstream_utils.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+char* picoquic_connection_id_to_string(const picoquic_connection_id_t* cid) {
+    // Each byte needs 2 hex characters + null terminator
+    char* str = malloc((cid->id_len * 2 + 1) * sizeof(char));
+    if (str == NULL) {
+        return NULL;
+    }
+
+    // Convert each byte to hex
+    for (int i = 0; i < cid->id_len; i++) {
+        sprintf(&str[i * 2], "%02x", cid->id[i]);
+    }
+    str[cid->id_len * 2] = '\0';
+
+    return str;
+}
+
+// Function to create a dummy sockaddr_storage with hardcoded IPv4 and port
+void sockaddr_dummy(struct sockaddr_storage *addr_storage) {
+    // Clear the entire sockaddr_storage to avoid residual data
+    memset(addr_storage, 0, sizeof(struct sockaddr_storage));
+
+    // Cast sockaddr_storage to sockaddr_in for IPv4
+    struct sockaddr_in *addr4 = (struct sockaddr_in *)addr_storage;
+
+    // Set address family to AF_INET (IPv4)
+    addr4->sin_family = AF_INET;
+
+    // Use a hardcoded IPv4 address: 192.0.2.1 (TEST-NET-1 for testing)
+    inet_pton(AF_INET, "192.0.2.1", &addr4->sin_addr);
+
+    // Set a hardcoded port: 12345
+    addr4->sin_port = htons(12345);
+
+#ifdef __APPLE__ // For BSD systems, set sin_len
+    addr4->sin_len = sizeof(struct sockaddr_in);
+#endif
+}