Remove sslkeylog file setup from quic-hq-interop

Now that libcrypto supports the user of SSLKEYLOGFILE, the interop demo
attempts to open the same file based on the same env variable.

The hq-interop-demo code can just be removed, and it fixes the open
failure when both libcrypto and hq-interop attempt to open and write the
same file, which is causing the nightly failure

Reviewed-by: Paul Dale <[email protected]>
Reviewed-by: Matt Caswell <[email protected]>
(Merged from openssl#25819)

demos/guide/quic-hq-interop.c

@@ -55,7 +55,6 @@
 #include <openssl/err.h>
 
 static int handle_io_failure(SSL *ssl, int res);
-static int set_keylog_file(SSL_CTX *ctx, const char *keylog_file);
 
 #define REQ_STRING_SZ 1024
 
@@ -73,18 +72,6 @@ static int set_keylog_file(SSL_CTX *ctx, const char *keylog_file);
  */
 static BIO *session_bio = NULL;
 
-/**
- * @brief A static pointer to a BIO object used for logging key material.
- *
- * This variable holds a reference to a BIO object that is used to log
- * cryptographic key material for debugging purposes. It is initialized to
- * NULL and should be assigned a valid BIO object before use.
- *
- * @note This variable is static, meaning it is only accessible within the
- * file in which it is declared.
- */
-static BIO *bio_keylog = NULL;
-
 /**
  * @brief Creates a BIO object for a UDP socket connection to a server.
  *
@@ -349,84 +336,6 @@ static int handle_io_failure(SSL *ssl, int res)
     }
 }
 
-/**
- * @brief Callback function to log key material during an SSL session.
- *
- * This function is invoked by OpenSSL when key material needs to be logged
- * for debugging purposes. It writes the provided key log line to the
- * `bio_keylog` BIO, ensuring thread-safe output by writing the entire line
- * at once.
- *
- * @param ssl A pointer to the SSL object associated with the session.
- * @param line The key log line to be written.
- *
- * @note If `bio_keylog` is NULL, an error message is printed to stderr, and
- * the function returns without logging the key material.
- */
-static void keylog_callback(const SSL *ssl, const char *line)
-{
-    if (bio_keylog == NULL) {
-        fprintf(stderr, "Keylog callback is invoked without valid file!\n");
-        return;
-    }
-
-    /*
-     * There might be concurrent writers to the keylog file, so we must ensure
-     * that the given line is written at once.
-     */
-    BIO_printf(bio_keylog, "%s\n", line);
-    (void)BIO_flush(bio_keylog);
-}
-
-/**
- * @brief Sets up the key logging file for an SSL context.
- *
- * This function configures a file to log SSL/TLS key material for the
- * provided SSL context. If a keylog file is specified, it will be opened
- * in append mode, allowing for concurrent writes and preserving existing
- * logs. If no keylog file is provided, key logging is disabled.
- *
- * @param ctx A pointer to the SSL_CTX object where the keylog file is set.
- * @param keylog_file The path to the keylog file. If NULL, key logging is
- *                    disabled.
- * @return 0 on success, or 1 if there was an error opening the keylog file.
- *
- * @note The function writes a header to the keylog file if it is empty and
- * seekable. It also ensures that any previously opened keylog files are
- * closed before opening a new one.
- */
-static int set_keylog_file(SSL_CTX *ctx, const char *keylog_file)
-{
-    /* Close any open files */
-    BIO_free_all(bio_keylog);
-    bio_keylog = NULL;
-
-    if (ctx == NULL || keylog_file == NULL) {
-        /* Keylogging is disabled, OK. */
-        return 0;
-    }
-
-    /*
-     * Append rather than write in order to allow concurrent modification.
-     * Furthermore, this preserves existing keylog files which is useful when
-     * the tool is run multiple times.
-     */
-    bio_keylog = BIO_new_file(keylog_file, "a");
-    if (bio_keylog == NULL) {
-        printf("Error writing keylog file %s\n", keylog_file);
-        return 1;
-    }
-
-    /* Write a header for seekable, empty files (this excludes pipes). */
-    if (BIO_tell(bio_keylog) == 0) {
-        BIO_puts(bio_keylog,
-                 "# SSL/TLS secrets log file, generated by OpenSSL\n");
-        (void)BIO_flush(bio_keylog);
-    }
-    SSL_CTX_set_keylog_callback(ctx, keylog_callback);
-    return 0;
-}
-
 /**
  * @brief A static integer indicating whether the session is cached.
  *
@@ -778,7 +687,6 @@ static int setup_connection(char *hostname, char *port, int ipv6,
 {
     unsigned char alpn[] = {10, 'h', 'q', '-', 'i', 'n', 't', 'e', 'r', 'o', 'p'};
     int ret = 0;
-    char *sslkeylogfile = NULL;
     BIO *bio = NULL;
 
     /*
@@ -810,11 +718,6 @@ static int setup_connection(char *hostname, char *port, int ipv6,
         goto end;
     }
 
-    sslkeylogfile = getenv("SSLKEYLOGFILE");
-    if (sslkeylogfile != NULL)
-        if (set_keylog_file(*ctx, sslkeylogfile))
-            goto end;
-
     /*
      * If the SSL_CIPHER_SUITES env variable is set, assign those
      * ciphers to the context