ping: fix write-after-allocated-mem bug

ping: use monotonic_us instead of gettimeofday: smaller code and
      needs only 4 bytes in the packet
ping: display roundtrip times with 1/1000th of ms, not 1/10 ms precision.
wget: small optimization

function                                             old     new   delta
pingstats                                            243     259     +16
sendping6                                             98      93      -5
sendping4                                            183     178      -5
.rodata                                           129715  129707      -8
progressmeter                                        867     855     -12
unpack_tail                                          320     272     -48
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/5 up/down: 16/-78)            Total: -62 bytes

1 files changed, 29 insertions, 34 deletions

diff --git a/networking/ping.c b/networking/ping.c
index e94b7914f..c4a498cd8 100644
--- a/networking/ping.c
+++ b/networking/ping.c
@@ -242,8 +242,8 @@ struct globals {
         int if_index;
         unsigned long ntransmitted, nreceived, nrepeats, pingcount;
         uint16_t myid;
-        unsigned tmin, tmax;
-        unsigned long tsum;
+        unsigned tmin, tmax; /* in us */
+        unsigned long long tsum; /* in us, sum of all times */
         const char *hostname;
         const char *dotted;
         union {
@@ -301,11 +301,13 @@ static void pingstats(int junk ATTRIBUTE_UNUSED)
         if (ntransmitted)
                 ntransmitted = (ntransmitted - nreceived) * 100 / ntransmitted;
         printf("%lu%% packet loss\n", ntransmitted);
-        if (tmin != UINT_MAX)
-                printf("round-trip min/avg/max = %u.%u/%lu.%lu/%u.%u ms\n",
-                        tmin / 10, tmin % 10,
-                        (tsum / (nreceived + nrepeats)) / 10,
-                        (tsum / (nreceived + nrepeats)) % 10, tmax / 10, tmax % 10);
+        if (tmin != UINT_MAX) {
+                unsigned tavg = tsum / (nreceived + nrepeats);
+                printf("round-trip min/avg/max = %u.%03u/%u.%03u/%u.%03u ms\n",
+                        tmin / 1000, tmin % 1000,
+                        tavg / 1000, tavg % 1000,
+                        tmax / 1000, tmax % 1000);
+        }
         exit(nreceived == 0); /* (nreceived == 0) is true (1) -- 'failure' */
 }
 
@@ -334,7 +336,9 @@ static void sendping_tail(void (*sp)(int), const void *pkt, int size_pkt)
 
 static void sendping4(int junk ATTRIBUTE_UNUSED)
 {
-        struct icmp *pkt = alloca(datalen + ICMP_MINLEN);
+        /* +4 reserves a place for timestamp, which may end up sitting
+         * *after* packet. Saves one if() */
+        struct icmp *pkt = alloca(datalen + ICMP_MINLEN + 4);
 
         pkt->icmp_type = ICMP_ECHO;
         pkt->icmp_code = 0;
@@ -342,10 +346,9 @@ static void sendping4(int junk ATTRIBUTE_UNUSED)
         pkt->icmp_seq = htons(ntransmitted); /* don't ++ here, it can be a macro */
         pkt->icmp_id = myid;
 
-// I can't fucking believe someone thought it's okay to do it like this...
-// where's hton? Where is a provision for different word size, structure padding, etc??
-// FIXME!
-        gettimeofday((struct timeval *) &pkt->icmp_dun, NULL);
+        /* We don't do hton, because we will read it back on the same machine */
+        /*if (datalen >= 4)*/
+                *(uint32_t*)&pkt->icmp_dun = monotonic_us();
 
         pkt->icmp_cksum = in_cksum((unsigned short *) pkt, datalen + ICMP_MINLEN);
 
@@ -354,7 +357,7 @@ static void sendping4(int junk ATTRIBUTE_UNUSED)
 #if ENABLE_PING6
 static void sendping6(int junk ATTRIBUTE_UNUSED)
 {
-        struct icmp6_hdr *pkt = alloca(datalen + sizeof(struct icmp6_hdr));
+        struct icmp6_hdr *pkt = alloca(datalen + sizeof(struct icmp6_hdr) + 4);
 
         pkt->icmp6_type = ICMP6_ECHO_REQUEST;
         pkt->icmp6_code = 0;
@@ -362,8 +365,8 @@ static void sendping6(int junk ATTRIBUTE_UNUSED)
         pkt->icmp6_seq = htons(ntransmitted); /* don't ++ here, it can be a macro */
         pkt->icmp6_id = myid;
 
-// FIXME!
-        gettimeofday((struct timeval *) &pkt->icmp6_data8[4], NULL);
+        /*if (datalen >= 4)*/
+                *(uint32_t*)(&pkt->icmp6_data8[4]) = monotonic_us();
 
         sendping_tail(sendping6, pkt, datalen + sizeof(struct icmp6_hdr));
 }
@@ -417,7 +420,7 @@ static const char *icmp6_type_name(int id)
 }
 #endif
 
-static void unpack_tail(int sz, struct timeval *tp,
+static void unpack_tail(int sz, uint32_t *tp,
                 const char *from_str,
                 uint16_t recv_seq, int ttl)
 {
@@ -427,17 +430,9 @@ static void unpack_tail(int sz, struct timeval *tp,
         ++nreceived;
 
         if (tp) {
-                struct timeval tv;
-
-                gettimeofday(&tv, NULL);
-                tv.tv_usec -= tp->tv_usec;
-                if (tv.tv_usec < 0) {
-                        --tv.tv_sec;
-                        tv.tv_usec += 1000000;
-                }
-                tv.tv_sec -= tp->tv_sec;
-
-                triptime = tv.tv_sec * 10000 + (tv.tv_usec / 100);
+                /* (int32_t) cast is for hypothetical 64-bit unsigned */
+                /* (doesn't hurt 32-bit real-world anyway) */
+                triptime = (int32_t) ((uint32_t)monotonic_us() - *tp);
                 tsum += triptime;
                 if (triptime < tmin)
                         tmin = triptime;
@@ -459,7 +454,7 @@ static void unpack_tail(int sz, struct timeval *tp,
         printf("%d bytes from %s: seq=%u ttl=%d", sz,
                 from_str, recv_seq, ttl);
         if (tp)
-                printf(" time=%u.%u ms", triptime / 10, triptime % 10);
+                printf(" time=%u.%03u ms", triptime / 1000, triptime % 1000);
         puts(dupmsg);
         fflush(stdout);
 }
@@ -483,10 +478,10 @@ static void unpack4(char *buf, int sz, struct sockaddr_in *from)
 
         if (icmppkt->icmp_type == ICMP_ECHOREPLY) {
                 uint16_t recv_seq = ntohs(icmppkt->icmp_seq);
-                struct timeval *tp = NULL;
+                uint32_t *tp = NULL;
 
-                if (sz >= ICMP_MINLEN + sizeof(struct timeval))
-                        tp = (struct timeval *) icmppkt->icmp_data;
+                if (sz >= ICMP_MINLEN + sizeof(uint32_t))
+                        tp = (uint32_t *) icmppkt->icmp_data;
                 unpack_tail(sz, tp,
                         inet_ntoa(*(struct in_addr *) &from->sin_addr.s_addr),
                         recv_seq, iphdr->ttl);
@@ -512,10 +507,10 @@ static void unpack6(char *packet, int sz, struct sockaddr_in6 *from, int hoplimi
 
         if (icmppkt->icmp6_type == ICMP6_ECHO_REPLY) {
                 uint16_t recv_seq = ntohs(icmppkt->icmp6_seq);
-                struct timeval *tp = NULL;
+                uint32_t *tp = NULL;
 
-                if (sz >= sizeof(struct icmp6_hdr) + sizeof(struct timeval))
-                        tp = (struct timeval *) &icmppkt->icmp6_data8[4];
+                if (sz >= sizeof(struct icmp6_hdr) + sizeof(uint32_t))
+                        tp = (uint32_t *) &icmppkt->icmp6_data8[4];
                 unpack_tail(sz, tp,
                         inet_ntop(AF_INET6, &pingaddr.sin6.sin6_addr,
                                         buf, sizeof(buf)),