passt: Address new clang-tidy warnings from LLVM 13.0.1

clang-tidy from LLVM 13.0.1 reports some new warnings from these
checkers:

- altera-unroll-loops, altera-id-dependent-backward-branch: ignore
  for the moment being, add a TODO item

- bugprone-easily-swappable-parameters: ignore, nothing to do about
  those

- readability-function-cognitive-complexity: ignore for the moment
  being, add a TODO item

- altera-struct-pack-align: ignore, alignment is forced in protocol
  headers

- concurrency-mt-unsafe: ignore for the moment being, add a TODO
  item

Fix bugprone-implicit-widening-of-multiplication-result warnings,
though, that's doable and they seem to make sense.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

9 files changed, 52 insertions, 25 deletions

diff --git a/Makefile b/Makefile
index 443c39d..5085578 100644
--- a/Makefile
+++ b/Makefile
@@ -167,6 +167,23 @@ pkgs:
 #
 # - bugprone-suspicious-string-compare
 #	Return value of memcmp(), not really suspicious
+#
+# - altera-unroll-loops
+# - altera-id-dependent-backward-branch
+#	TODO: check paths where it might make sense to improve performance
+#
+# - bugprone-easily-swappable-parameters
+#	Not much can be done about them other than being careful
+#
+# - readability-function-cognitive-complexity
+#	TODO: split reported functions
+#
+# - altera-struct-pack-align
+#	"Poor" alignment needed for structs reflecting message formats/headers
+#
+# - concurrency-mt-unsafe
+#	TODO: check again if multithreading is implemented
+
 clang-tidy: $(wildcard *.c) $(wildcard *.h)
 	clang-tidy -checks=*,-modernize-*,\
 	-clang-analyzer-valist.Uninitialized,\
@@ -187,7 +204,12 @@ clang-tidy: $(wildcard *.c) $(wildcard *.h)
 	-bugprone-narrowing-conversions,\
 	-cppcoreguidelines-narrowing-conversions,\
 	-cppcoreguidelines-avoid-non-const-global-variables,\
-	-bugprone-suspicious-string-compare \
+	-bugprone-suspicious-string-compare,\
+	-altera-unroll-loops,-altera-id-dependent-backward-branch,\
+	-bugprone-easily-swappable-parameters,\
+	-readability-function-cognitive-complexity,\
+	-altera-struct-pack-align,\
+	-concurrency-mt-unsafe \
 	--warnings-as-errors=* $(wildcard *.c) -- $(CFLAGS)
 
 ifeq ($(shell $(CC) -v 2>&1 | grep -c "gcc version"),1)
diff --git a/checksum.c b/checksum.c
index c9905d1..acb1e3e 100644
--- a/checksum.c
+++ b/checksum.c
@@ -108,10 +108,13 @@ uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init)
  */
 void csum_tcp4(struct iphdr *iph)
 {
-	struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
-	uint16_t tlen = ntohs(iph->tot_len) - iph->ihl * 4, *p = (uint16_t *)th;
+	uint16_t tlen = ntohs(iph->tot_len) - iph->ihl * 4, *p;
+	struct tcphdr *th;
 	uint32_t sum = 0;
 
+	th = (struct tcphdr *)((char *)iph + (intptr_t)(iph->ihl * 4));
+	p = (uint16_t *)th;
+
 	sum += (iph->saddr >> 16) & 0xffff;
 	sum += iph->saddr & 0xffff;
 	sum += (iph->daddr >> 16) & 0xffff;
diff --git a/conf.c b/conf.c
index 9a9dade..abe63a1 100644
--- a/conf.c
+++ b/conf.c
@@ -867,7 +867,7 @@ void conf(struct ctx *c, int argc, char **argv)
 
 			for (i = 0; i < ETH_ALEN; i++) {
 				errno = 0;
-				b = strtol(optarg + i * 3, NULL, 16);
+				b = strtol(optarg + (intptr_t)i * 3, NULL, 16);
 				if (b < 0 || b > UCHAR_MAX || errno) {
 					err("Invalid MAC address: %s", optarg);
 					usage(argv[0]);
@@ -1032,7 +1032,7 @@ void conf(struct ctx *c, int argc, char **argv)
 		case 'M':
 			for (i = 0; i < ETH_ALEN; i++) {
 				errno = 0;
-				b = strtol(optarg + i * 3, NULL, 16);
+				b = strtol(optarg + (intptr_t)i * 3, NULL, 16);
 				if (b < 0 || b > UCHAR_MAX || errno) {
 					err("Invalid MAC address: %s", optarg);
 					usage(argv[0]);
diff --git a/dhcp.c b/dhcp.c
index 0d6d698..a052397 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -271,10 +271,10 @@ int dhcp(struct ctx *c, struct ethhdr *eh, size_t len)
 	if (len < sizeof(*eh) + sizeof(*iph))
 		return 0;
 
-	if (len < sizeof(*eh) + iph->ihl * 4 + sizeof(*uh))
+	if (len < sizeof(*eh) + (long)iph->ihl * 4 + sizeof(*uh))
 		return 0;
 
-	uh = (struct udphdr *)((char *)iph + iph->ihl * 4);
+	uh = (struct udphdr *)((char *)iph + (long)(iph->ihl * 4));
 	m = (struct msg *)(uh + 1);
 
 	if (uh->dest != htons(67))
@@ -283,7 +283,7 @@ int dhcp(struct ctx *c, struct ethhdr *eh, size_t len)
 	if (c->no_dhcp)
 		return 1;
 
-	mlen = len - sizeof(*eh) - iph->ihl * 4 - sizeof(*uh);
+	mlen = len - sizeof(*eh) - (long)iph->ihl * 4 - sizeof(*uh);
 	if (mlen != ntohs(uh->len) - sizeof(*uh) ||
 	    mlen < offsetof(struct msg, o) ||
 	    m->op != BOOTREQUEST)
@@ -349,7 +349,7 @@ int dhcp(struct ctx *c, struct ethhdr *eh, size_t len)
 	iph->daddr = c->addr4;
 	iph->saddr = c->gw4;
 	iph->check = 0;
-	iph->check = csum_unaligned(iph, iph->ihl * 4, 0);
+	iph->check = csum_unaligned(iph, (intptr_t)(iph->ihl * 4), 0);
 
 	len += sizeof(*eh);
 	memcpy(eh->h_dest, eh->h_source, ETH_ALEN);
diff --git a/qrap.c b/qrap.c
index 1eb82fa..3ee73a7 100644
--- a/qrap.c
+++ b/qrap.c
@@ -111,7 +111,7 @@ void usage(const char *name)
  */
 int main(int argc, char **argv)
 {
-	struct timeval tv = { .tv_sec = 0, .tv_usec = 500 * 1000 };
+	struct timeval tv = { .tv_sec = 0, .tv_usec = (long)(500 * 1000) };
 	int i, s, qemu_argc = 0, addr_map = 0, has_dev = 0;
 	char *qemu_argv[ARG_MAX], dev_str[ARG_MAX];
 	struct sockaddr_un addr = {
diff --git a/tap.c b/tap.c
index 34a5705..22db9c5 100644
--- a/tap.c
+++ b/tap.c
@@ -131,7 +131,7 @@ void tap_ip_send(struct ctx *c, struct in6_addr *src, uint8_t proto,
 		memcpy(&iph->saddr, &src->s6_addr[12], 4);
 
 		iph->check = 0;
-		iph->check = csum_unaligned(iph, iph->ihl * 4, 0);
+		iph->check = csum_unaligned(iph, (size_t)iph->ihl * 4, 0);
 
 		memcpy(data, in, len);
 
@@ -337,9 +337,9 @@ resume:
 			continue;
 
 		iph = (struct iphdr *)(eh + 1);
-		if ((iph->ihl * 4) + sizeof(*eh) > len)
+		if ((size_t)iph->ihl * 4 + sizeof(*eh) > len)
 			continue;
-		if (iph->ihl * 4 < (int)sizeof(*iph))
+		if ((size_t)iph->ihl * 4 < (int)sizeof(*iph))
 			continue;
 
 		if (iph->saddr && c->addr4_seen != iph->saddr) {
@@ -347,7 +347,7 @@ resume:
 			proto_update_l2_buf(NULL, NULL, &c->addr4_seen);
 		}
 
-		l4h = (char *)iph + iph->ihl * 4;
+		l4h = (char *)iph + (size_t)iph->ihl * 4;
 		l4_len = len - ((intptr_t)l4h - (intptr_t)eh);
 
 		if (iph->protocol == IPPROTO_ICMP) {
diff --git a/tcp.c b/tcp.c
index 7122898..723b18e 100644
--- a/tcp.c
+++ b/tcp.c
@@ -345,7 +345,7 @@
 
 #define TCP_TAP_FRAMES			256
 
-#define MAX_PIPE_SIZE			(2 * 1024 * 1024)
+#define MAX_PIPE_SIZE			(2UL * 1024 * 1024)
 
 #define TCP_HASH_TABLE_LOAD		70		/* % */
 #define TCP_HASH_TABLE_SIZE		(MAX_TAP_CONNS * 100 /		\
@@ -1040,8 +1040,8 @@ static int tcp_opt_get(struct tcphdr *th, size_t len, uint8_t type_search,
 	uint8_t type, optlen;
 	char *p;
 
-	if (len > (unsigned)th->doff * 4)
-		len = th->doff * 4;
+	if (len > (size_t)th->doff * 4)
+		len = (size_t)th->doff * 4;
 
 	len -= sizeof(*th);
 	p = (char *)(th + 1);
@@ -1568,7 +1568,7 @@ static int tcp_update_seqack_wnd(struct ctx *c, struct tcp_tap_conn *conn,
 #else
 	if (conn->state > ESTABLISHED || (flags & (DUP_ACK | FORCE_ACK)) ||
 	    conn->local || tcp_rtt_dst_low(conn) ||
-	    conn->snd_buf < SNDBUF_SMALL) {
+	    (unsigned long)conn->snd_buf < SNDBUF_SMALL) {
 		conn->seq_ack_to_tap = conn->seq_from_tap;
 	} else if (conn->seq_ack_to_tap != conn->seq_from_tap) {
 		if (!tinfo) {
@@ -2393,7 +2393,7 @@ static void tcp_data_from_tap(struct ctx *c, struct tcp_tap_conn *conn,
 			return;
 		}
 
-		off = th->doff * 4;
+		off = (size_t)th->doff * 4;
 		if (off < sizeof(*th) || off > len) {
 			tcp_rst(c, conn);
 			return;
diff --git a/util.c b/util.c
index 46a539b..57b987a 100644
--- a/util.c
+++ b/util.c
@@ -51,7 +51,7 @@ void name(const char *format, ...) {					\
 		clock_gettime(CLOCK_REALTIME, &tp);			\
 		fprintf(stderr, "%li.%04li: ",				\
 			tp.tv_sec - log_debug_start,			\
-			tp.tv_nsec / (100 * 1000));			\
+			tp.tv_nsec / (100L * 1000));			\
 	} else {							\
 		va_start(args, format);					\
 		passt_vsyslog(level, format, args);			\
@@ -305,12 +305,14 @@ void sock_probe_mem(struct ctx *c)
 
 	sl = sizeof(v);
 	if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, &v, sizeof(v))	||
-	    getsockopt(s, SOL_SOCKET, SO_SNDBUF, &v, &sl) || v < SNDBUF_BIG)
+	    getsockopt(s, SOL_SOCKET, SO_SNDBUF, &v, &sl) ||
+	    (size_t)v < SNDBUF_BIG)
 		c->low_wmem = 1;
 
 	v = INT_MAX / 2;
 	if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, &v, sizeof(v))	||
-	    getsockopt(s, SOL_SOCKET, SO_RCVBUF, &v, &sl) || v < RCVBUF_BIG)
+	    getsockopt(s, SOL_SOCKET, SO_RCVBUF, &v, &sl) ||
+	    (size_t)v < RCVBUF_BIG)
 		c->low_rmem = 1;
 
 	close(s);
diff --git a/util.h b/util.h
index 800a91d..add4c1e 100644
--- a/util.h
+++ b/util.h
@@ -144,9 +144,9 @@ enum {
 		.daddr		= IN6ADDR_ANY_INIT,			\
 	}
 
-#define RCVBUF_BIG		(2 * 1024 * 1024)
-#define SNDBUF_BIG		(4 * 1024 * 1024)
-#define SNDBUF_SMALL		(128 * 1024)
+#define RCVBUF_BIG		(2UL * 1024 * 1024)
+#define SNDBUF_BIG		(4UL * 1024 * 1024)
+#define SNDBUF_SMALL		(128UL * 1024)
 
 #include <net/if.h>
 #include <limits.h>