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Ensure we discard unread/unsent data when abandoning a connection attempt.
authorTom Lane <tgl@sss.pgh.pa.us>
Sat, 27 Aug 2011 18:16:39 +0000 (14:16 -0400)
committerTom Lane <tgl@sss.pgh.pa.us>
Sat, 27 Aug 2011 18:16:39 +0000 (14:16 -0400)
There are assorted situations wherein PQconnectPoll() will abandon a
connection attempt and try again with different parameters (eg, SSL versus
not SSL).  However, the code forgot to discard any pending data in libpq's
I/O buffers when doing this.  In at least one case (server returns E
message during SSL negotiation), there is unread input data which bollixes
the next connection attempt.  I have not checked to see whether this is
possible in the other cases where we close the socket and retry, but it
seems like a matter of good defensive programming to add explicit
buffer-flushing code to all of them.

This is one of several issues exposed by Daniel Farina's report of
misbehavior after a server-side fork failure.

This has been wrong since forever, so back-patch to all supported branches.

src/interfaces/libpq/fe-connect.c patch | blob | blame | history

diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 58d70bd4d965eb469b65c50b08e94066c40d19d8..318edd41065c196ad16932c87f7a09f854aaba22 100644 (file)
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1379,6 +1379,9 @@ keep_going:                       /* We will come back to here until there is
                        closesocket(conn->sock);
                        conn->sock = -1;
                        conn->status = CONNECTION_NEEDED;
+                       /* Discard any unread/unsent data */
+                       conn->inStart = conn->inCursor = conn->inEnd = 0;
+                       conn->outCount = 0;
                        goto keep_going;
                    }
                    else
@@ -1416,6 +1419,9 @@ keep_going:                       /* We will come back to here until there is
                        closesocket(conn->sock);
                        conn->sock = -1;
                        conn->status = CONNECTION_NEEDED;
+                       /* Discard any unread/unsent data */
+                       conn->inStart = conn->inCursor = conn->inEnd = 0;
+                       conn->outCount = 0;
                        goto keep_going;
                    }
                }
@@ -1528,6 +1534,9 @@ keep_going:                       /* We will come back to here until there is
                        closesocket(conn->sock);
                        conn->sock = -1;
                        conn->status = CONNECTION_NEEDED;
+                       /* Discard any unread/unsent data */
+                       conn->inStart = conn->inCursor = conn->inEnd = 0;
+                       conn->outCount = 0;
                        goto keep_going;
                    }
 
@@ -1594,6 +1603,9 @@ keep_going:                       /* We will come back to here until there is
                        closesocket(conn->sock);
                        conn->sock = -1;
                        conn->status = CONNECTION_NEEDED;
+                       /* Discard any unread/unsent data */
+                       conn->inStart = conn->inCursor = conn->inEnd = 0;
+                       conn->outCount = 0;
                        goto keep_going;
                    }
 
@@ -1613,6 +1625,9 @@ keep_going:                       /* We will come back to here until there is
                        closesocket(conn->sock);
                        conn->sock = -1;
                        conn->status = CONNECTION_NEEDED;
+                       /* Discard any unread/unsent data */
+                       conn->inStart = conn->inCursor = conn->inEnd = 0;
+                       conn->outCount = 0;
                        goto keep_going;
                    }
 #endif
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