LibC: getprotoent() family of functions

This commit implements the getprotoent() family of functions, including

getprotoent()
getprotobyname()
getprotobynumber()
setprotoent()
endprotoent()

This implementation is very similar to the getservent family of functions,
which is what led to the discovery of a bug in the process of reading the aliases.
The ByteBuffer for the alias strings didn't include a null terminating character,
this was fixed for both the protoent and servent family of functions by appending a
null character to the end of them before adding them to the alias lists.

2 files changed, 208 insertions, 1 deletions

diff --git a/Libraries/LibC/netdb.cpp b/Libraries/LibC/netdb.cpp
index f58d45f02c..bc8aebc400 100644
--- a/Libraries/LibC/netdb.cpp
+++ b/Libraries/LibC/netdb.cpp
@@ -49,6 +49,7 @@ static hostent __gethostbyaddr_buffer;
 static char __gethostbyaddr_name_buffer[512];
 static in_addr_t* __gethostbyaddr_address_list_buffer[2];
 
+//Get service entry buffers and file information for the getservent() family of functions
 static FILE* services_file = nullptr;
 static const char* services_path = "/etc/services";
 
@@ -62,6 +63,19 @@ static Vector<char*> __getserv_alias_list;
 static bool keep_service_file_open = false;
 static ssize_t service_file_offset = 0;
 
+//Get protocol entry buffers and file information for the getprotent() family of functions
+static FILE* protocols_file = nullptr;
+static const char* protocols_path = "/etc/protocols";
+
+static bool fill_getproto_buffers(char* line, ssize_t read);
+static protoent __getproto_buffer;
+static char __getproto_name_buffer[512];
+static Vector<ByteBuffer> __getproto_alias_list_buffer;
+static Vector<char*> __getproto_alias_list;
+static int __getproto_protocol_buffer;
+static bool keep_protocols_file_open = false;
+static ssize_t protocol_file_offset = 0;
+
 static int connect_to_lookup_server()
 {
     int fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
@@ -263,9 +277,11 @@ struct servent* getservent()
     __getserv_buffer.s_port = __getserv_port_buffer;
     __getserv_buffer.s_proto = __getserv_protocol_buffer;
 
+    __getserv_alias_list.clear();
     for (auto& alias : __getserv_alias_list_buffer) {
         __getserv_alias_list.append((char*)alias.data());
     }
+
     __getserv_buffer.s_aliases = __getserv_alias_list.data();
     service_entry = &__getserv_buffer;
 
@@ -395,7 +411,185 @@ static bool fill_getserv_buffers(char* line, ssize_t read)
             if (split_line[i].starts_with('#')) {
                 break;
             }
-            __getserv_alias_list_buffer.append(split_line[i].to_byte_buffer());
+            auto alias = split_line[i].to_byte_buffer();
+            alias.append("\0", sizeof(char));
+            __getserv_alias_list_buffer.append(alias);
+        }
+    }
+
+    return true;
+}
+
+struct protoent* getprotoent()
+{
+    //If protocols file isn't open, attempt to open and return null on failure.
+    if (!protocols_file) {
+        protocols_file = fopen(protocols_path, "r");
+
+        if (!protocols_file) {
+            perror("error opening protocols file");
+            return nullptr;
+        }
+    }
+
+    if (fseek(protocols_file, protocol_file_offset, SEEK_SET) != 0) {
+        perror("error seeking protocols file");
+        fclose(protocols_file);
+        return nullptr;
+    }
+
+    char* line = nullptr;
+    size_t len = 0;
+    ssize_t read;
+
+    auto free_line_on_exit = ScopeGuard([line] {
+        if (line) {
+            free(line);
+        }
+    });
+
+    do {
+        read = getline(&line, &len, protocols_file);
+        protocol_file_offset += read;
+        if (read > 0 && (line[0] >= 65 && line[0] <= 122)) {
+            break;
+        }
+    } while (read != -1);
+
+    if (read == -1) {
+        fclose(protocols_file);
+        protocols_file = nullptr;
+        protocol_file_offset = 0;
+        return nullptr;
+    }
+
+    struct protoent* protocol_entry = nullptr;
+    if (!fill_getproto_buffers(line, read))
+        return nullptr;
+
+    __getproto_buffer.p_name = __getproto_name_buffer;
+    __getproto_buffer.p_proto = __getproto_protocol_buffer;
+
+    __getproto_alias_list.clear();
+
+    for (auto& alias : __getproto_alias_list_buffer) {
+        __getproto_alias_list.append((char*)alias.data());
+    }
+
+    __getproto_buffer.p_aliases = __getproto_alias_list.data();
+    protocol_entry = &__getproto_buffer;
+
+    if (!keep_protocols_file_open)
+        endprotoent();
+
+    return protocol_entry;
+}
+
+struct protoent* getprotobyname(const char* name)
+{
+    bool previous_file_open_setting = keep_protocols_file_open;
+    setprotoent(1);
+    struct protoent* current_protocol = nullptr;
+    auto protocol_file_handler = ScopeGuard([previous_file_open_setting] {
+        if (!previous_file_open_setting) {
+            endprotoent();
+        }
+    });
+
+    while (true) {
+        current_protocol = getprotoent();
+        if (current_protocol == nullptr)
+            break;
+        else if (strcmp(current_protocol->p_name, name) == 0)
+            break;
+    }
+
+    return current_protocol;
+}
+
+struct protoent* getprotobynumber(int proto)
+{
+    bool previous_file_open_setting = keep_protocols_file_open;
+    setprotoent(1);
+    struct protoent* current_protocol = nullptr;
+    auto protocol_file_handler = ScopeGuard([previous_file_open_setting] {
+        if (!previous_file_open_setting) {
+            endprotoent();
+        }
+    });
+
+    while (true) {
+        current_protocol = getprotoent();
+        if (current_protocol == nullptr)
+            break;
+        else if (current_protocol->p_proto == proto)
+            break;
+    }
+
+    return current_protocol;
+}
+
+void setprotoent(int stay_open)
+{
+    if (!protocols_file) {
+        protocols_file = fopen(protocols_path, "r");
+
+        if (!protocols_file) {
+            perror("error opening protocols file");
+            return;
+        }
+    }
+    rewind(protocols_file);
+    keep_protocols_file_open = stay_open;
+    protocol_file_offset = 0;
+}
+
+void endprotoent()
+{
+    if (!protocols_file) {
+        return;
+    }
+    fclose(protocols_file);
+    protocols_file = nullptr;
+}
+
+static bool fill_getproto_buffers(char* line, ssize_t read)
+{
+    String string_line = String(line, read);
+    string_line.replace(" ", "\t", true);
+    auto split_line = string_line.split('\t');
+
+    //This indicates an incorrect file format. Protocols file entries should always have at least a name and a protocol.
+    if (split_line.size() < 2) {
+        perror("malformed protocols file: entry");
+        return false;
+    }
+    if (sizeof(__getproto_name_buffer) >= split_line[0].length() + 1) {
+        strncpy(__getproto_name_buffer, split_line[0].characters(), split_line[0].length() + 1);
+    } else {
+        perror("invalid buffer length: protocol name");
+        return false;
+    }
+
+    bool conversion_checker;
+    __getproto_protocol_buffer = split_line[1].to_int(conversion_checker);
+
+    if (!conversion_checker) {
+        return false;
+    }
+
+    __getproto_alias_list_buffer.clear();
+
+    //If there are aliases for the protocol, we will fill the alias list buffer.
+    if (split_line.size() > 2 && !split_line[2].starts_with('#')) {
+
+        for (size_t i = 2; i < split_line.size(); i++) {
+            if (split_line[i].starts_with('#')) {
+                break;
+            }
+            auto alias = split_line[i].to_byte_buffer();
+            alias.append("\0", sizeof(char));
+            __getproto_alias_list_buffer.append(alias);
         }
     }
 
diff --git a/Libraries/LibC/netdb.h b/Libraries/LibC/netdb.h
index 802c89a39d..c2bd5a130f 100644
--- a/Libraries/LibC/netdb.h
+++ b/Libraries/LibC/netdb.h
@@ -55,6 +55,19 @@ struct servent* getservbyname(const char* name, const char* protocol);
 struct servent* getservbyport(int port, const char* protocol);
 void setservent(int stay_open);
 void endservent();
+
+struct protoent {
+    char* p_name;
+    char** p_aliases;
+    int p_proto;
+};
+
+void endprotoent();
+struct protoent* getprotobyname(const char* name);
+struct protoent* getprotobynumber(int proto);
+struct protoent* getprotoent();
+void setprotoent(int stay_open);
+
 extern int h_errno;
 
 #define HOST_NOT_FOUND 101