Fix bugs in protocol file parsing

Protocol numbers were being used as a short in network byte order
instead of host byte order, so this command would fail:
nmap -sO -p tcp

Additionally, duplicate protocols would not be reported correctly. This
change speeds up lookups and simplifies the code.

protocols.cc

@@ -64,16 +64,29 @@
 
 #include "protocols.h"
 #include "NmapOps.h"
-#include "charpool.h"
+#include "string_pool.h"
 #include "nmap_error.h"
 #include "utils.h"
 
+#include <map>
+
 extern NmapOps o;
-static int numipprots = 0;
-static struct protocol_list *protocol_table[PROTOCOL_TABLE_SIZE];
-static int protocols_initialized = 0;
+
+struct strcmp_comparator {
+  bool operator()(const char *a, const char *b) const {
+    return strcmp(a, b) < 0;
+  }
+};
+
+// IP Protocol number is 8 bits wide
+// protocol_table[IPPROTO_TCP] == {"tcp", 6}
+static struct nprotoent *protocol_table[UCHAR_MAX];
+// proto_map["tcp"] = {"tcp", 6}
+typedef std::map<const char *, struct nprotoent, strcmp_comparator> ProtoMap;
+static ProtoMap proto_map;
 
 static int nmap_protocols_init() {
+  static int protocols_initialized = 0;
   if (protocols_initialized) return 0;
 
   char filename[512];
@@ -83,7 +96,6 @@ static int nmap_protocols_init() {
   char *p;
   char line[1024];
   int lineno = 0;
-  struct protocol_list *current, *previous;
   int res;
 
   if (nmap_fetchfile(filename, sizeof(filename), "nmap-protocols") != 1) {
@@ -108,35 +120,27 @@ static int nmap_protocols_init() {
     if (*p == '#')
       continue;
     res = sscanf(line, "%127s %hu", protocolname, &protno);
-    if (res !=2)
+    if (res !=2 || protno > UCHAR_MAX) {
+      error("Parse error in protocols file %s line %d", filename, lineno);
       continue;
+    }
+
+    struct nprotoent ent;
+    // Using string_pool means we don't have to copy this data; the pointer is unique!
+    ent.p_name = string_pool_insert(protocolname);
+    ent.p_proto = protno;
+    std::pair<ProtoMap::iterator, bool> status = proto_map.insert(std::pair<const char *, struct nprotoent>(ent.p_name, ent));
 
     /* Now we make sure our protocols don't have duplicates */
-    for(current = protocol_table[protno % PROTOCOL_TABLE_SIZE], previous = NULL;
-        current; current = current->next) {
-      if (protno == current->protoent->p_proto) {
-        if (o.debugging) {
-          error("Protocol %d is duplicated in protocols file %s", ntohs(protno), filename);
+    if (!status.second) {
+      if (o.debugging > 1) {
+        error("Protocol %d is duplicated in protocols file %s", protno, filename);
       }
-        break;
-      }
-      previous = current;
-    }
-    if (current)
       continue;
-
-    numipprots++;
-
-    current = (struct protocol_list *) cp_alloc(sizeof(struct protocol_list));
-    current->protoent = (struct nprotoent *) cp_alloc(sizeof(struct nprotoent));
-    current->next = NULL;
-    if (previous == NULL) {
-      protocol_table[protno % PROTOCOL_TABLE_SIZE] = current;
-    } else {
-      previous->next = current;
     }
-    current->protoent->p_name = cp_strdup(protocolname);
-    current->protoent->p_proto = protno;
+
+    assert(!protocol_table[protno]);
+    protocol_table[protno] = &status.first->second;
   }
   fclose(fp);
   protocols_initialized = 1;
@@ -151,18 +155,24 @@ static int nmap_protocols_init() {
 
 
 int addprotocolsfromservmask(char *mask, u8 *porttbl) {
-  struct protocol_list *current;
-  int bucket, t=0;
+  ProtoMap::const_iterator it;
+  int t=0;
 
-  if (!protocols_initialized && nmap_protocols_init() == -1)
+  if (nmap_protocols_init() != 0)
     fatal("%s: Couldn't get protocol numbers", __func__);
 
-  for(bucket = 0; bucket < PROTOCOL_TABLE_SIZE; bucket++) {
-    for(current = protocol_table[bucket % PROTOCOL_TABLE_SIZE]; current; current = current->next) {
-      if (wildtest(mask, current->protoent->p_name)) {
-        porttbl[ntohs(current->protoent->p_proto)] |= SCAN_PROTOCOLS;
-        t++;
+  // Check for easy ones: plain string match.
+  it = proto_map.find(mask);
+  if (it != proto_map.end()) {
+    // Matched! No need to try wildtest on everything.
+    porttbl[it->second.p_proto] |= SCAN_PROTOCOLS;
+    return 1;
   }
+  // No match? iterate and use wildtest.
+  for(it = proto_map.begin(); it != proto_map.end(); it++) {
+    if (wildtest(mask, it->second.p_name)) {
+      porttbl[it->second.p_proto] |= SCAN_PROTOCOLS;
+      t++;
     }
   }
 
@@ -172,17 +182,10 @@ int addprotocolsfromservmask(char *mask, u8 *porttbl) {
 
 
 struct nprotoent *nmap_getprotbynum(int num) {
-  struct protocol_list *current;
 
   if (nmap_protocols_init() == -1)
     return NULL;
 
-  for(current = protocol_table[num % PROTOCOL_TABLE_SIZE];
-      current; current = current->next) {
-    if (num == current->protoent->p_proto)
-      return current->protoent;
-  }
-
-  /* Couldn't find it ... oh well. */
-  return NULL;
+  assert(num >= 0 && num < UCHAR_MAX);
+  return protocol_table[num];
 }

protocols.h

@@ -75,18 +75,11 @@
 #include "libnetutil/netutil.h"
 #endif
 
-#define PROTOCOL_TABLE_SIZE 256
-
 struct nprotoent {
   const char *p_name;
   short p_proto;
 };
 
-struct protocol_list {
-  struct nprotoent *protoent;
-  struct protocol_list *next;
-};
-
 int addprotocolsfromservmask(char *mask, u8 *porttbl);
 struct nprotoent *nmap_getprotbynum(int num);