Implement select() for timeout and flush.

wolfSSL · Jan 17, 2024 · 985ee60 · 985ee60
1 parent fec34be
commit 985ee60
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Showing 2 changed files with 52 additions and 20 deletions.
diff --git a/docs/SWTPM.md b/docs/SWTPM.md
@@ -4,6 +4,8 @@ wolfTPM is to be able to interface with software TPM (SW TPM) interfaces defined
 
 The SWTPM interface is not compatible with TIS or devtpm (/dev/tpm0). Transport is a socket connection by default, but can also be a UART.
 
+This implementation only uses the TPM command interface typically on port 2321. It does not support the Platform interface typically on port 2322.
+
 Software TPM implementations tested:
 * https://github.com/kgoldman/ibmswtpm2 or https://sourceforge.net/projects/ibmswtpm2/files/
 * https://github.com/microsoft/ms-tpm-20-ref
@@ -31,7 +33,7 @@ make
 * `TPM2_SWTPM_HOST`: The host TPM address (default=localhost)
 * `TPM2_SWTPM_PORT`: The socket port (default=2321)
 * `WOLFTPM_SWTPM_UART`: Use UART transport (no TIS layer)
-* `WOLFTPM_SWTPM_UARTFLUSH`: Force a read flush on connect.
+
 
 ## SWTPM simulator setup
 

diff --git a/src/tpm2_swtpm.c b/src/tpm2_swtpm.c
@@ -68,6 +68,9 @@
     #ifndef TPM2_SWTPM_PORT
     #define TPM2_SWTPM_PORT         115200
     #endif
+    #ifndef TPM2_TIMEOUT_SECONDS
+    #define TPM2_TIMEOUT_SECONDS    60
+    #endif
 #else
     #include <wolftpm/tpm2_socket.h>
 
@@ -77,8 +80,12 @@
     #ifndef TPM2_SWTPM_PORT
     #define TPM2_SWTPM_PORT         "2321"
     #endif
+    #ifndef TPM2_TIMEOUT_SECONDS
+    #define TPM2_TIMEOUT_SECONDS    10
+    #endif
 #endif /* WOLFTPM_SWTPM_UART */
 
+
 static TPM_RC SwTpmTransmit(TPM2_CTX* ctx, const void* buffer, ssize_t bufSz)
 {
     TPM_RC rc = TPM_RC_SUCCESS;
@@ -88,6 +95,11 @@ static TPM_RC SwTpmTransmit(TPM2_CTX* ctx, const void* buffer, ssize_t bufSz)
         return BAD_FUNC_ARG;
     }
 
+#ifdef DEBUG_SWTPM_IO
+    printf("Write %zd\n", bufSz);
+    TPM2_PrintBin(buffer, (word32)bufSz);
+#endif
+
     wrc = write(ctx->tcpCtx.fd, buffer, bufSz);
     if (bufSz != wrc) {
         rc = TPM_RC_FAILURE;
@@ -103,23 +115,41 @@ static TPM_RC SwTpmTransmit(TPM2_CTX* ctx, const void* buffer, ssize_t bufSz)
     return rc;
 }
 
-static TPM_RC SwTpmReceive(TPM2_CTX* ctx, void* buffer, size_t rxSz)
+static int SwTpmReceive(TPM2_CTX* ctx, void* buffer, size_t rxSz)
 {
-    TPM_RC rc = TPM_RC_SUCCESS;
-    ssize_t wrc = 0;
-    size_t bytes_remaining = rxSz;
+    int rc;
+    size_t remain;
     char* ptr = (char*)buffer;
+    fd_set rfds;
+    struct timeval tv = { TPM2_TIMEOUT_SECONDS, 0};
 
     if (ctx == NULL || ctx->tcpCtx.fd < 0 || buffer == NULL) {
         return BAD_FUNC_ARG;
     }
 
-    while (bytes_remaining > 0) {
-        wrc = read(ctx->tcpCtx.fd, ptr, bytes_remaining);
-        if (wrc <= 0) {
+    FD_ZERO(&rfds);
+    FD_SET(ctx->tcpCtx.fd, &rfds);
+
+    remain = rxSz;
+    while (remain > 0) {
+        /* use select to wait for data */
+        rc = select(ctx->tcpCtx.fd + 1, &rfds, NULL, NULL, &tv);
+        if (rc == 0) {
+            rc = SOCKET_ERROR_E; /* timeout */
+            break;
+        }
+        rc = (int)read(ctx->tcpCtx.fd, ptr, remain);
+#ifdef DEBUG_SWTPM_IO
+        printf("Read asked %zd, got %d\n", remain, rc);
+#endif
+        if (rc <= 0) {
         #ifdef DEBUG_WOLFTPM
-            if (wrc == 0) {
+            if (rc == 0) {
+            #ifdef WOLFTPM_SWTPM_UART
+                continue; /* keep trying */
+            #else
                 printf("Failed to read from TPM socket: EOF\n");
+            #endif
             }
             else {
                 printf("Failed to read from TPM socket %d, got errno %d"
@@ -130,14 +160,20 @@ static TPM_RC SwTpmReceive(TPM2_CTX* ctx, void* buffer, size_t rxSz)
             break;
         }
 
-        bytes_remaining -= wrc;
-        ptr += wrc;
+#ifdef DEBUG_SWTPM_IO
+        TPM2_PrintBin((const byte*)ptr, rc);
+#endif
+        remain -= rc;
+        ptr += rc;
 
     #ifdef WOLFTPM_DEBUG_VERBOSE
-        printf("TPM socket received %zd waiting for %zu more\n",
-               wrc, bytes_remaining);
+        printf("TPM socket received %d waiting for %zu more\n",
+               rc, remain);
     #endif
     }
+    if (remain == 0) {
+        rc = TPM_RC_SUCCESS;
+    }
 
     return rc;
 }
@@ -146,9 +182,6 @@ static TPM_RC SwTpmReceive(TPM2_CTX* ctx, void* buffer, size_t rxSz)
 static int SwTpmConnect(TPM2_CTX* ctx, const char* uartDev, uint32_t baud)
 {
     struct termios tty;
-#ifdef WOLFTPM_SWTPM_UARTFLUSH
-    byte readBuf[100];
-#endif
     int fd;
 
     if (ctx == NULL) {
@@ -178,11 +211,8 @@ static int SwTpmConnect(TPM2_CTX* ctx, const char* uartDev, uint32_t baud)
     tty.c_cc[VTIME] = 5;
     tcsetattr(fd, TCSANOW, &tty);
 
-#ifdef WOLFTPM_SWTPM_UARTFLUSH
     /* Flush any data in the RX buffer */
-    (void)read(fd, readBuf, sizeof(readBuf));
-    /* Ignore RX error on flush */
-#endif
+    tcflush(fd, TCIOFLUSH);
 
     /* save file descriptor to context */
     ctx->tcpCtx.fd = fd;