<p>Kévin Redon has uploaded this change for <strong>review</strong>.</p><p><a href="https://gerrit.osmocom.org/9966">View Change</a></p><pre style="font-family: monospace,monospace; white-space: pre-wrap;">sniff: add checksum verification for ATR and PPS<br><br>a checksum error is only signaled in the USB message with the<br>corresponding flag.<br><br>Change-Id: I277868267c3199eea216ab47bdd09fb2fb944b06<br>---<br>M firmware/libcommon/include/simtrace_prot.h<br>M firmware/libcommon/source/sniffer.c<br>M host/simtrace2-sniff.c<br>3 files changed, 28 insertions(+), 3 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">git pull ssh://gerrit.osmocom.org:29418/simtrace2 refs/changes/66/9966/1</pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/firmware/libcommon/include/simtrace_prot.h b/firmware/libcommon/include/simtrace_prot.h</span><br><span>index f1f736b..58e51be 100644</span><br><span>--- a/firmware/libcommon/include/simtrace_prot.h</span><br><span>+++ b/firmware/libcommon/include/simtrace_prot.h</span><br><span>@@ -297,6 +297,7 @@</span><br><span> /* SIMTRACE_MSGT_SNIFF_ATR, SIMTRACE_MSGT_SNIFF_PPS, SIMTRACE_MSGT_SNIFF_TPDU flags */</span><br><span> #define SNIFF_DATA_FLAG_ERROR_INCOMPLETE (1<<5)</span><br><span> #define SNIFF_DATA_FLAG_ERROR_MALFORMED (1<<6)</span><br><span style="color: hsl(120, 100%, 40%);">+#define SNIFF_DATA_FLAG_ERROR_CHECKSUM (1<<7)</span><br><span> </span><br><span> /* SIMTRACE_MSGT_SNIFF_CHANGE */</span><br><span> struct sniff_change {</span><br><span>diff --git a/firmware/libcommon/source/sniffer.c b/firmware/libcommon/source/sniffer.c</span><br><span>index c58b047..f99c25a 100644</span><br><span>--- a/firmware/libcommon/source/sniffer.c</span><br><span>+++ b/firmware/libcommon/source/sniffer.c</span><br><span>@@ -394,6 +394,7 @@</span><br><span> static uint8_t atr_hist_len = 0; /* store the number of expected historical bytes */</span><br><span> static uint8_t y = 0; /* last mask of the upcoming TA, TB, TC, TD interface bytes */</span><br><span> static uint8_t i = 0; /* interface byte subgroup number */</span><br><span style="color: hsl(120, 100%, 40%);">+ static uint32_t flags = 0; /* error flag */</span><br><span> </span><br><span> /* sanity check */</span><br><span> if (ISO7816_S_IN_ATR != iso_state) {</span><br><span>@@ -411,6 +412,7 @@</span><br><span> /* handle ATR byte depending on current state */</span><br><span> switch (atr_state) {</span><br><span> case ATR_S_WAIT_TS: /* see ISO/IEC 7816-3:2006 section 8.1 */</span><br><span style="color: hsl(120, 100%, 40%);">+ flags = 0;</span><br><span> switch (byte) {</span><br><span> case 0x23: /* direct convention used, but decoded using inverse convention (a parity error should also have occurred) */</span><br><span> case 0x30: /* inverse convention used, but decoded using direct convention (a parity error should also have occurred) */</span><br><span>@@ -480,8 +482,21 @@</span><br><span> break;</span><br><span> }</span><br><span> case ATR_S_WAIT_TCK: /* see ISO/IEC 7816-3:2006 section 8.2.5 */</span><br><span style="color: hsl(0, 100%, 40%);">- /* we could verify the checksum, but we are just here to sniff */</span><br><span style="color: hsl(0, 100%, 40%);">- usb_send_atr(0); /* send ATR to host software using USB */</span><br><span style="color: hsl(120, 100%, 40%);">+ /* verify checksum if present */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (ATR_S_WAIT_TCK == atr_state) {</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t ui;</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t checksum = 0;</span><br><span style="color: hsl(120, 100%, 40%);">+ for (ui = 1; ui < atr_i; atr_i++) {</span><br><span style="color: hsl(120, 100%, 40%);">+ checksum ^= atr[ui];</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ if (checksum) {</span><br><span style="color: hsl(120, 100%, 40%);">+ flags |= SNIFF_DATA_FLAG_ERROR_CHECKSUM;</span><br><span style="color: hsl(120, 100%, 40%);">+ /* We still consider the data as valid (e.g. for WT) even is the checksum is wrong.</span><br><span style="color: hsl(120, 100%, 40%);">+ * It is up to the reader to handle this error (e.g. by resetting)</span><br><span style="color: hsl(120, 100%, 40%);">+ */</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ usb_send_atr(flags); /* send ATR to host software using USB */</span><br><span> change_state(ISO7816_S_WAIT_TPDU); /* go to next state */</span><br><span> break;</span><br><span> default:</span><br><span>@@ -551,6 +566,7 @@</span><br><span> static void process_byte_pps(uint8_t byte)</span><br><span> {</span><br><span> uint8_t *pps_cur; /* current PPS (request or response) */</span><br><span style="color: hsl(120, 100%, 40%);">+ static uint32_t flags = 0; /* error flag */</span><br><span> </span><br><span> /* sanity check */</span><br><span> if (ISO7816_S_IN_PPS_REQ == iso_state) {</span><br><span>@@ -565,6 +581,7 @@</span><br><span> /* handle PPS byte depending on current state */</span><br><span> switch (pps_state) { /* see ISO/IEC 7816-3:2006 section 9.2 */</span><br><span> case PPS_S_WAIT_PPSS: /*!< initial byte */</span><br><span style="color: hsl(120, 100%, 40%);">+ flags = 0;</span><br><span> if (0xff) {</span><br><span> pps_cur[0] = byte;</span><br><span> pps_state = PPS_S_WAIT_PPS0; /* go to next state */</span><br><span>@@ -613,8 +630,11 @@</span><br><span> check ^= pps_cur[4];</span><br><span> }</span><br><span> check ^= pps_cur[5];</span><br><span style="color: hsl(120, 100%, 40%);">+ if (check) {</span><br><span style="color: hsl(120, 100%, 40%);">+ flags |= SNIFF_DATA_FLAG_ERROR_CHECKSUM;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span> pps_state = PPS_S_WAIT_END;</span><br><span style="color: hsl(0, 100%, 40%);">- usb_send_pps(0); /* send PPS to host software using USB */</span><br><span style="color: hsl(120, 100%, 40%);">+ usb_send_pps(flags); /* send PPS to host software using USB */</span><br><span> if (ISO7816_S_IN_PPS_REQ == iso_state) {</span><br><span> if (0 == check) { /* checksum is valid */</span><br><span> change_state(ISO7816_S_WAIT_PPS_RSP); /* go to next state */</span><br><span>diff --git a/host/simtrace2-sniff.c b/host/simtrace2-sniff.c</span><br><span>index 765ced3..64cc354 100644</span><br><span>--- a/host/simtrace2-sniff.c</span><br><span>+++ b/host/simtrace2-sniff.c</span><br><span>@@ -131,6 +131,10 @@</span><br><span> .flag = SNIFF_DATA_FLAG_ERROR_MALFORMED,</span><br><span> .meaning = "malformed",</span><br><span> },</span><br><span style="color: hsl(120, 100%, 40%);">+ {</span><br><span style="color: hsl(120, 100%, 40%);">+ .flag = SNIFF_DATA_FLAG_ERROR_CHECKSUM,</span><br><span style="color: hsl(120, 100%, 40%);">+ .meaning = "checksum error",</span><br><span style="color: hsl(120, 100%, 40%);">+ },</span><br><span> };</span><br><span> </span><br><span> static void print_flags(const struct flag_meaning_t* flag_meanings, uint32_t nb_flags, uint32_t flags) {</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/9966">change 9966</a>. 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<div style="display:none"> Gerrit-Project: simtrace2 </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-MessageType: newchange </div>
<div style="display:none"> Gerrit-Change-Id: I277868267c3199eea216ab47bdd09fb2fb944b06 </div>
<div style="display:none"> Gerrit-Change-Number: 9966 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: Kévin Redon <kredon@sysmocom.de> </div>