HTTP, SoftEther, Florensia: fix some memory corruptions

```
==12308==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60600068f4b4 at pc 0x5603d2b56098 bp 0x7ffc967bd3b0 sp 0x7ffc967bd3a8
READ of size 2 at 0x60600068f4b4 thread T0
    #0 0x5603d2b56097 in ndpi_search_florensia /home/ivan/svnrepos/nDPI/src/lib/protocols/florensia.c:93:40
    ntop#1 0x5603d2a2e835 in check_ndpi_detection_func /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:5414:6
    ntop#2 0x5603d2a2f247 in check_ndpi_tcp_flow_func /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:5462:12
    ntop#3 0x5603d2a2eee7 in ndpi_check_flow_func /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:5481:12
    ntop#4 0x5603d2a3ffb5 in ndpi_detection_process_packet /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:6308:15
    ntop#5 0x5603d2955f4c in packet_processing /home/ivan/svnrepos/nDPI/example/reader_util.c:1612:31
    ntop#6 0x5603d294ee64 in ndpi_workflow_process_packet /home/ivan/svnrepos/nDPI/example/reader_util.c:2182:10
    ntop#7 0x5603d290aa50 in LLVMFuzzerTestOneInput /home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader.c:107:7
    ntop#8 0x5603d290ab8b in main /home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader.c:179:17
    ntop#9 0x7f972cdc9082 in __libc_start_main /build/glibc-SzIz7B/glibc-2.31/csu/../csu/libc-start.c:308:16
    ntop#10 0x5603d28494fd in _start (/home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader_with_main+0x4be4fd) (BuildId: e81373a75c70e248ba9ae985fcb4134e7113121a)
```
```
==14164==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60d0000000c1 at pc 0x561608bada2c bp 0x7ffc40d38ed0 sp 0x7ffc40d38690
READ of size 10 at 0x60d0000000c1 thread T0
    #0 0x561608bada2b in __interceptor_strncpy (/home/ivan/svnrepos/nDPI/fuzz/fuzz_process_packet_with_main+0x4e9a2b) (BuildId: 2e4fd67f1aeb93c491a04ae424331669c993ee9b)
    ntop#1 0x561608e66f2a in dissect_softether_host_fqdn /home/ivan/svnrepos/nDPI/src/lib/protocols/softether.c:226:2
    ntop#2 0x561608e64e88 in ndpi_search_softether /home/ivan/svnrepos/nDPI/src/lib/protocols/softether.c:316:8
    ntop#3 0x561608ca7475 in check_ndpi_detection_func /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:5414:6
    ntop#4 0x561608ca823b in check_ndpi_udp_flow_func /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:5450:10
    ntop#5 0x561608ca7bdc in ndpi_check_flow_func /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:5483:12
    ntop#6 0x561608cb8bf5 in ndpi_detection_process_packet /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:6308:15
    ntop#7 0x561608bff84e in LLVMFuzzerTestOneInput /home/ivan/svnrepos/nDPI/fuzz/fuzz_process_packet.c:29:5
    ntop#8 0x561608bff9c7 in main /home/ivan/svnrepos/nDPI/fuzz/fuzz_process_packet.c:101:17
    ntop#9 0x7fc50662d082 in __libc_start_main /build/glibc-SzIz7B/glibc-2.31/csu/../csu/libc-start.c:308:16
    ntop#10 0x561608b3e42d in _start (/home/ivan/svnrepos/nDPI/fuzz/fuzz_process_packet_with_main+0x47a42d) (BuildId: 2e4fd67f1aeb93c491a04ae424331669c993ee9b)
```

Found by oss-fuzzer.
See: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=50105
See: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=50110
See: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=50268

src/lib/protocols/florensia.c

@@ -90,7 +90,8 @@ void ndpi_search_florensia(struct ndpi_detection_module_struct *ndpi_struct, str
 	ndpi_florensia_add_connection(ndpi_struct, flow);
 	return;
       }
-      if (flow->packet_counter < 10 && get_l16(packet->payload, 0) == packet->payload_packet_len) {
+      if (flow->packet_counter < 10 && packet->payload_packet_len >=2 &&
+	  get_l16(packet->payload, 0) == packet->payload_packet_len) {
 	NDPI_LOG_DBG2(ndpi_struct, "maybe florensia\n");
 	return;
       }

src/lib/protocols/http.c

@@ -855,7 +855,8 @@ static void check_content_type_and_change_protocol(struct ndpi_detection_module_
       /* Matching on Content-Type.
           OCSP:  application/ocsp-request, application/ocsp-response
        */
-      if(strncmp((const char *)packet->content_line.ptr, "application/ocsp-", 17) == 0) {
+      if(packet->content_line.len > 17 &&
+         strncmp((const char *)packet->content_line.ptr, "application/ocsp-", 17) == 0) {
         NDPI_LOG_DBG2(ndpi_struct, "Found OCSP\n");
         ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_OCSP, NDPI_PROTOCOL_HTTP, NDPI_CONFIDENCE_DPI);
       }

src/lib/protocols/softether.c

@@ -97,7 +97,7 @@ static size_t dissect_softether_type(enum softether_value_type t,
 
       v->value.ptr.raw = payload + 4;
       u_int32_t siz = ntohl(get_u_int32_t(payload, 0));
-      if(siz == 0 || (u_int64_t)payload_len < (u_int64_t)siz + 3)
+      if(siz == 0 || (u_int64_t)payload_len < (u_int64_t)siz + sizeof(siz))
 	return 0;
 
       if(t == VALUE_DATA)