postgresql源码学习（46）—— PostmasterMain(3) 监听套接字与客户端认证
继续学习后面的部分
一、 创建监听套接字
1. 预备知识
- ListenAddresses：字符串，用于存储服务器IP地址，以逗号分隔
extern char *ListenAddresses;- ListenSocket[MAXLISTEN]：整型数组，保存与服务器上某个IP地址绑定的套接字描述符。初始时全为-1，MAXLISTEN为64。
/* The socket(s) we're listening to. */
#define MAXLISTEN 64
static pgsocket ListenSocket[MAXLISTEN];2. 相关代码
/*
* Establish input sockets.
*
* First, mark them all closed, and set up an on_proc_exit function that's charged with closing the sockets again at postmaster shutdown.
*/
for (i = 0; i < MAXLISTEN; i++)
ListenSocket[i] = PGINVALID_SOCKET;
on_proc_exit(CloseServerPorts, 0);
/* 如果ListenAddresses非空 */
if (ListenAddresses)
{
char *rawstring;
List *elemlist;
ListCell *l;
int success = 0;
/* Need a modifiable copy of ListenAddresses */
rawstring = pstrdup(ListenAddresses);
/* Parse string into list of hostnames，解析ListenAddresses获取ip地址或主机名 */
if (!SplitGUCList(rawstring, ',', &elemlist))
{
/* syntax error in list */
ereport(FATAL,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid list syntax in parameter \"%s\"",
"listen_addresses")));
}
/* 循环处理解析出来的每个ip */
foreach(l, elemlist)
{
char *curhost = (char *) lfirst(l);
/* 如果不为*，调用StreamServerPort函数创建套接字，注意第二个参数为NULL */
if (strcmp(curhost, "*") == 0)
status = StreamServerPort(AF_UNSPEC, NULL,
(unsigned short) PostPortNumber,
NULL,
ListenSocket, MAXLISTEN);
else
/* 否则，也是调用StreamServerPort函数创建套接字，但第二个参数为curhost */
status = StreamServerPort(AF_UNSPEC, curhost,
(unsigned short) PostPortNumber,
NULL,
ListenSocket, MAXLISTEN);
/* 创建成功 */
if (status == STATUS_OK)
{
success++;
/* record the first successful host addr in lockfile，在lockfile中记录第一个成功的地址 */
if (!listen_addr_saved)
{
AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, curhost);
listen_addr_saved = true;
}
}
else
ereport(WARNING,
(errmsg("could not create listen socket for \"%s\"",
curhost)));
}
if (!success && elemlist != NIL)
ereport(FATAL,
(errmsg("could not create any TCP/IP sockets")));
list_free(elemlist);
pfree(rawstring);
}
二、 读取客户端认证的配置文件
调用load_hba()函数和load_ident()函数读取客户端认证文件pg_hba.conf和pg_ident.conf。
/*
* Load configuration files for client authentication.
*/
if (!load_hba())
{
/*
* It makes no sense to continue if we fail to load the HBA file,
* since there is no way to connect to the database in this case.
*/
ereport(FATAL,
(errmsg("could not load pg_hba.conf")));
}
if (!load_ident())
{
/*
* We can start up without the IDENT file, although it means that you
* cannot log in using any of the authentication methods that need a
* user name mapping. load_ident() already logged the details of error
* to the log.
*/
}1. load_hba函数
/*
* Read the config file and create a List of HbaLine records for the contents.
*
* The configuration is read into a temporary list, and if any parse error
* occurs the old list is kept in place and false is returned. Only if the
* whole file parses OK is the list replaced, and the function returns true.
*
* On a false result, caller will take care of reporting a FATAL error in case
* this is the initial startup. If it happens on reload, we just keep running
* with the old data.
*/
bool
load_hba(void)
{
FILE *file;
List *hba_lines = NIL;
ListCell *line;
List *new_parsed_lines = NIL;
bool ok = true;
MemoryContext linecxt;
MemoryContext oldcxt;
MemoryContext hbacxt;
file = AllocateFile(HbaFileName, "r");
if (file == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open configuration file \"%s\": %m",
HbaFileName)));
return false;
}
linecxt = tokenize_file(HbaFileName, file, &hba_lines, LOG);
FreeFile(file);
/* Now parse all the lines */
Assert(PostmasterContext);
hbacxt = AllocSetContextCreate(PostmasterContext,
"hba parser context",
ALLOCSET_SMALL_SIZES);
oldcxt = MemoryContextSwitchTo(hbacxt);
foreach(line, hba_lines)
{
TokenizedLine *tok_line = (TokenizedLine *) lfirst(line);
HbaLine *newline;
/* don't parse lines that already have errors */
if (tok_line->err_msg != NULL)
{
ok = false;
continue;
}
if ((newline = parse_hba_line(tok_line, LOG)) == NULL)
{
/* Parse error; remember there's trouble */
ok = false;
/*
* Keep parsing the rest of the file so we can report errors on
* more than the first line. Error has already been logged, no
* need for more chatter here.
*/
continue;
}
new_parsed_lines = lappend(new_parsed_lines, newline);
}
/*
* A valid HBA file must have at least one entry; else there's no way to
* connect to the postmaster. But only complain about this if we didn't
* already have parsing errors.
*/
if (ok && new_parsed_lines == NIL)
{
ereport(LOG,
(errcode(ERRCODE_CONFIG_FILE_ERROR),
errmsg("configuration file \"%s\" contains no entries",
HbaFileName)));
ok = false;
}
/* Free tokenizer memory */
MemoryContextDelete(linecxt);
MemoryContextSwitchTo(oldcxt);
if (!ok)
{
/* File contained one or more errors, so bail out */
MemoryContextDelete(hbacxt);
return false;
}
/* Loaded new file successfully, replace the one we use */
if (parsed_hba_context != NULL)
MemoryContextDelete(parsed_hba_context);
parsed_hba_context = hbacxt;
parsed_hba_lines = new_parsed_lines;
return true;
}2. load_ident函数
这个文件没有不影响启动，代码跟前一个函数有点像
/*
* Read the ident config file and create a List of IdentLine records for
* the contents.
*
* This works the same as load_hba(), but for the user config file.
*/
bool
load_ident(void)
{
FILE *file;
List *ident_lines = NIL;
ListCell *line_cell,
*parsed_line_cell;
List *new_parsed_lines = NIL;
bool ok = true;
MemoryContext linecxt;
MemoryContext oldcxt;
MemoryContext ident_context;
IdentLine *newline;
file = AllocateFile(IdentFileName, "r");
if (file == NULL)
{
/* not fatal ... we just won't do any special ident maps */
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open usermap file \"%s\": %m",
IdentFileName)));
return false;
}
linecxt = tokenize_file(IdentFileName, file, &ident_lines, LOG);
FreeFile(file);
/* Now parse all the lines */
Assert(PostmasterContext);
ident_context = AllocSetContextCreate(PostmasterContext,
"ident parser context",
ALLOCSET_SMALL_SIZES);
oldcxt = MemoryContextSwitchTo(ident_context);
foreach(line_cell, ident_lines)
{
TokenizedLine *tok_line = (TokenizedLine *) lfirst(line_cell);
/* don't parse lines that already have errors */
if (tok_line->err_msg != NULL)
{
ok = false;
continue;
}
if ((newline = parse_ident_line(tok_line)) == NULL)
{
/* Parse error; remember there's trouble */
ok = false;
/*
* Keep parsing the rest of the file so we can report errors on
* more than the first line. Error has already been logged, no
* need for more chatter here.
*/
continue;
}
new_parsed_lines = lappend(new_parsed_lines, newline);
}
/* Free tokenizer memory */
MemoryContextDelete(linecxt);
MemoryContextSwitchTo(oldcxt);
if (!ok)
{
/*
* File contained one or more errors, so bail out, first being careful
* to clean up whatever we allocated. Most stuff will go away via
* MemoryContextDelete, but we have to clean up regexes explicitly.
*/
foreach(parsed_line_cell, new_parsed_lines)
{
newline = (IdentLine *) lfirst(parsed_line_cell);
if (newline->ident_user[0] == '/')
pg_regfree(&newline->re);
}
MemoryContextDelete(ident_context);
return false;
}
/* Loaded new file successfully, replace the one we use */
if (parsed_ident_lines != NIL)
{
foreach(parsed_line_cell, parsed_ident_lines)
{
newline = (IdentLine *) lfirst(parsed_line_cell);
if (newline->ident_user[0] == '/')
pg_regfree(&newline->re);
}
}
if (parsed_ident_context != NULL)
MemoryContextDelete(parsed_ident_context);
parsed_ident_context = ident_context;
parsed_ident_lines = new_parsed_lines;
return true;
}参考
《PostgreSQL数据库内核分析》第二章
Postgres中postmaster代码解析(上) - JavaShuo