// -*- mode: cpp; mode: fold -*-
// Description /*{{{*/
-// $Id: http.cc,v 1.28 1999/03/15 06:01:00 jgg Exp $
+// $Id: http.cc,v 1.59 2004/05/08 19:42:35 mdz Exp $
/* ######################################################################
HTTP Aquire Method - This is the HTTP aquire method for APT.
It uses HTTP/1.1 and many of the fancy options there-in, such as
- pipelining, range, if-range and so on. It accepts on the command line
- a list of url destination pairs and writes to stdout the status of the
- operation as defined in the APT method spec.
-
- It is based on a doubly buffered select loop. All the requests are
+ pipelining, range, if-range and so on.
+
+ It is based on a doubly buffered select loop. A groupe of requests are
fed into a single output buffer that is constantly fed out the
socket. This provides ideal pipelining as in many cases all of the
requests will fit into a single packet. The input socket is buffered
- the same way and fed into the fd for the file.
+ the same way and fed into the fd for the file (may be a pipe in future).
This double buffering provides fairly substantial transfer rates,
compared to wget the http method is about 4% faster. Most importantly,
#include <apt-pkg/fileutl.h>
#include <apt-pkg/acquire-method.h>
#include <apt-pkg/error.h>
-#include <apt-pkg/md5.h>
+#include <apt-pkg/hashes.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
+#include <string.h>
+#include <apti18n.h>
// Internet stuff
-#include <netinet/in.h>
-#include <sys/socket.h>
-#include <arpa/inet.h>
#include <netdb.h>
+#include "connect.h"
+#include "rfc2553emu.h"
#include "http.h"
+
/*}}}*/
+using namespace std;
string HttpMethod::FailFile;
int HttpMethod::FailFd = -1;
time_t HttpMethod::FailTime = 0;
unsigned long PipelineDepth = 10;
unsigned long TimeOut = 120;
+bool Debug = false;
+URI Proxy;
+unsigned long CircleBuf::BwReadLimit=0;
+unsigned long CircleBuf::BwTickReadData=0;
+struct timeval CircleBuf::BwReadTick={0,0};
+const unsigned int CircleBuf::BW_HZ=10;
+
// CircleBuf::CircleBuf - Circular input buffer /*{{{*/
// ---------------------------------------------------------------------
/* */
-CircleBuf::CircleBuf(unsigned long Size) : Size(Size), MD5(0)
+CircleBuf::CircleBuf(unsigned long Size) : Size(Size), Hash(0)
{
Buf = new unsigned char[Size];
Reset();
+
+ CircleBuf::BwReadLimit = _config->FindI("Acquire::http::Dl-Limit",0)*1024;
}
/*}}}*/
// CircleBuf::Reset - Reset to the default state /*{{{*/
StrPos = 0;
MaxGet = (unsigned int)-1;
OutQueue = string();
- if (MD5 != 0)
+ if (Hash != 0)
{
- delete MD5;
- MD5 = new MD5Summation;
+ delete Hash;
+ Hash = new Hashes;
}
};
/*}}}*/
is non-blocking.. */
bool CircleBuf::Read(int Fd)
{
+ unsigned long BwReadMax;
+
while (1)
{
// Woops, buffer is full
if (InP - OutP == Size)
return true;
-
+
+ // what's left to read in this tick
+ BwReadMax = CircleBuf::BwReadLimit/BW_HZ;
+
+ if(CircleBuf::BwReadLimit) {
+ struct timeval now;
+ gettimeofday(&now,0);
+
+ unsigned long d = (now.tv_sec-CircleBuf::BwReadTick.tv_sec)*1000000 +
+ now.tv_usec-CircleBuf::BwReadTick.tv_usec;
+ if(d > 1000000/BW_HZ) {
+ CircleBuf::BwReadTick = now;
+ CircleBuf::BwTickReadData = 0;
+ }
+
+ if(CircleBuf::BwTickReadData >= BwReadMax) {
+ usleep(1000000/BW_HZ);
+ return true;
+ }
+ }
+
// Write the buffer segment
int Res;
- Res = read(Fd,Buf + (InP%Size),LeftRead());
+ if(CircleBuf::BwReadLimit) {
+ Res = read(Fd,Buf + (InP%Size),
+ BwReadMax > LeftRead() ? LeftRead() : BwReadMax);
+ } else
+ Res = read(Fd,Buf + (InP%Size),LeftRead());
+ if(Res > 0 && BwReadLimit > 0)
+ CircleBuf::BwTickReadData += Res;
+
if (Res == 0)
return false;
if (Res < 0)
unsigned long Sz = LeftRead();
if (OutQueue.length() - StrPos < Sz)
Sz = OutQueue.length() - StrPos;
- memcpy(Buf + (InP%Size),OutQueue.begin() + StrPos,Sz);
+ memcpy(Buf + (InP%Size),OutQueue.c_str() + StrPos,Sz);
// Advance
StrPos += Sz;
return false;
}
- if (MD5 != 0)
- MD5->Add(Buf + (OutP%Size),Res);
+ if (Hash != 0)
+ Hash->Add(Buf + (OutP%Size),Res);
OutP += Res;
}
{
if (Buf[I%Size] != '\n')
continue;
- for (I++; I < InP && Buf[I%Size] == '\r'; I++);
+ ++I;
if (Single == false)
{
- if (Buf[I%Size] != '\n')
- continue;
- for (I++; I < InP && Buf[I%Size] == '\r'; I++);
+ if (I < InP && Buf[I%Size] == '\r')
+ ++I;
+ if (I >= InP || Buf[I%Size] != '\n')
+ continue;
+ ++I;
}
- if (I > InP)
- I = InP;
-
Data = "";
while (OutP < I)
{
unsigned long Sz = LeftWrite();
if (Sz == 0)
return false;
- if (I - OutP < LeftWrite())
+ if (I - OutP < Sz)
Sz = I - OutP;
Data += string((char *)(Buf + (OutP%Size)),Sz);
OutP += Sz;
// ServerState::Open - Open a connection to the server /*{{{*/
// ---------------------------------------------------------------------
/* This opens a connection to the server. */
-string LastHost;
-in_addr LastHostA;
bool ServerState::Open()
{
// Use the already open connection if possible.
Close();
In.Reset();
Out.Reset();
-
+ Persistent = true;
+
// Determine the proxy setting
if (getenv("http_proxy") == 0)
{
else
Proxy = getenv("http_proxy");
+ // Parse no_proxy, a , separated list of domains
+ if (getenv("no_proxy") != 0)
+ {
+ if (CheckDomainList(ServerName.Host,getenv("no_proxy")) == true)
+ Proxy = "";
+ }
+
// Determine what host and port to use based on the proxy settings
- int Port = 80;
+ int Port = 0;
string Host;
- if (Proxy.empty() == true)
+ if (Proxy.empty() == true || Proxy.Host.empty() == true)
{
if (ServerName.Port != 0)
Port = ServerName.Port;
Host = Proxy.Host;
}
- /* We used a cached address record.. Yes this is against the spec but
- the way we have setup our rotating dns suggests that this is more
- sensible */
- if (LastHost != Host)
- {
- Owner->Status("Connecting to %s",Host.c_str());
-
- // Lookup the host
- hostent *Addr = gethostbyname(Host.c_str());
- if (Addr == 0 || Addr->h_addr_list[0] == 0)
- return _error->Error("Could not resolve '%s'",Host.c_str());
- LastHost = Host;
- LastHostA = *(in_addr *)(Addr->h_addr_list[0]);
- }
-
- Owner->Status("Connecting to %s (%s)",Host.c_str(),inet_ntoa(LastHostA));
-
- // Get a socket
- if ((ServerFd = socket(AF_INET,SOCK_STREAM,0)) < 0)
- return _error->Errno("socket","Could not create a socket");
-
- // Connect to the server
- struct sockaddr_in server;
- server.sin_family = AF_INET;
- server.sin_port = htons(Port);
- server.sin_addr = LastHostA;
- SetNonBlock(ServerFd,true);
- if (connect(ServerFd,(sockaddr *)&server,sizeof(server)) < 0 &&
- errno != EINPROGRESS)
- return _error->Errno("socket","Could not create a socket");
-
- /* This implements a timeout for connect by opening the connection
- nonblocking */
- if (WaitFd(ServerFd,true,TimeOut) == false)
- return _error->Error("Could not connect, connection timed out");
- unsigned int Err;
- unsigned int Len = sizeof(Err);
- if (getsockopt(ServerFd,SOL_SOCKET,SO_ERROR,&Err,&Len) != 0)
- return _error->Errno("getsockopt","Failed");
- if (Err != 0)
- return _error->Error("Could not connect.");
+ // Connect to the remote server
+ if (Connect(Host,Port,"http",80,ServerFd,TimeOut,Owner) == false)
+ return false;
return true;
}
{
State = Header;
- Owner->Status("Waiting for file");
+ Owner->Status(_("Waiting for headers"));
Major = 0;
Minor = 0;
string Data;
if (In.WriteTillEl(Data) == false)
continue;
+
+ if (Debug == true)
+ clog << Data;
for (string::const_iterator I = Data.begin(); I < Data.end(); I++)
{
string::const_iterator J = I;
for (; J != Data.end() && *J != '\n' && *J != '\r';J++);
- if (HeaderLine(string(I,J-I)) == false)
+ if (HeaderLine(string(I,J)) == false)
return 2;
I = J;
}
+
+ // 100 Continue is a Nop...
+ if (Result == 100)
+ continue;
+
+ // Tidy up the connection persistance state.
+ if (Encoding == Closes && HaveContent == true)
+ Persistent = false;
+
return 0;
}
while (Owner->Go(false,this) == true);
-
+
return 1;
}
/*}}}*/
// The http server might be trying to do something evil.
if (Line.length() >= MAXLEN)
- return _error->Error("Got a single header line over %u chars",MAXLEN);
+ return _error->Error(_("Got a single header line over %u chars"),MAXLEN);
string::size_type Pos = Line.find(' ');
if (Pos == string::npos || Pos+1 > Line.length())
- return _error->Error("Bad header line");
-
- string Tag = string(Line,0,Pos);
- string Val = string(Line,Pos+1);
+ {
+ // Blah, some servers use "connection:closes", evil.
+ Pos = Line.find(':');
+ if (Pos == string::npos || Pos + 2 > Line.length())
+ return _error->Error(_("Bad header line"));
+ Pos++;
+ }
- if (stringcasecmp(Tag.begin(),Tag.begin()+4,"HTTP") == 0)
+ // Parse off any trailing spaces between the : and the next word.
+ string::size_type Pos2 = Pos;
+ while (Pos2 < Line.length() && isspace(Line[Pos2]) != 0)
+ Pos2++;
+
+ string Tag = string(Line,0,Pos);
+ string Val = string(Line,Pos2);
+
+ if (stringcasecmp(Tag.c_str(),Tag.c_str()+4,"HTTP") == 0)
{
// Evil servers return no version
if (Line[4] == '/')
{
if (sscanf(Line.c_str(),"HTTP/%u.%u %u %[^\n]",&Major,&Minor,
&Result,Code) != 4)
- return _error->Error("The http server sent an invalid reply header");
+ return _error->Error(_("The HTTP server sent an invalid reply header"));
}
else
{
Major = 0;
Minor = 9;
if (sscanf(Line.c_str(),"HTTP %u %[^\n]",&Result,Code) != 2)
- return _error->Error("The http server sent an invalid reply header");
+ return _error->Error(_("The HTTP server sent an invalid reply header"));
}
-
+
+ /* Check the HTTP response header to get the default persistance
+ state. */
+ if (Major < 1)
+ Persistent = false;
+ else
+ {
+ if (Major == 1 && Minor <= 0)
+ Persistent = false;
+ else
+ Persistent = true;
+ }
+
return true;
}
return true;
if (sscanf(Val.c_str(),"%lu",&Size) != 1)
- return _error->Error("The http server sent an invalid Content-Length header");
+ return _error->Error(_("The HTTP server sent an invalid Content-Length header"));
return true;
}
HaveContent = true;
if (sscanf(Val.c_str(),"bytes %lu-%*u/%lu",&StartPos,&Size) != 2)
- return _error->Error("The http server sent an invalid Content-Range header");
+ return _error->Error(_("The HTTP server sent an invalid Content-Range header"));
if ((unsigned)StartPos > Size)
- return _error->Error("This http server has broken range support");
+ return _error->Error(_("This HTTP server has broken range support"));
return true;
}
{
HaveContent = true;
if (stringcasecmp(Val,"chunked") == 0)
- Encoding = Chunked;
-
+ Encoding = Chunked;
return true;
}
+ if (stringcasecmp(Tag,"Connection:") == 0)
+ {
+ if (stringcasecmp(Val,"close") == 0)
+ Persistent = false;
+ if (stringcasecmp(Val,"keep-alive") == 0)
+ Persistent = true;
+ return true;
+ }
+
if (stringcasecmp(Tag,"Last-Modified:") == 0)
{
if (StrToTime(Val,Date) == false)
- return _error->Error("Unknown date format");
+ return _error->Error(_("Unknown date format"));
return true;
}
will glitch HTTP/1.0 proxies because they do not filter it out and
pass it on, HTTP/1.1 says the connection should default to keep alive
and we expect the proxy to do this */
- if (Proxy.empty() == true)
+ if (Proxy.empty() == true || Proxy.Host.empty())
sprintf(Buf,"GET %s HTTP/1.1\r\nHost: %s\r\nConnection: keep-alive\r\n",
QuoteString(Uri.Path,"~").c_str(),ProperHost.c_str());
else
and a no-store directive for archives. */
sprintf(Buf,"GET %s HTTP/1.1\r\nHost: %s\r\n",
Itm->Uri.c_str(),ProperHost.c_str());
- if (_config->FindB("Acquire::http::No-Cache",false) == true)
- strcat(Buf,"Cache-Control: no-cache\r\nPragma: no-cache\r\n");
- else
+ // only generate a cache control header if we actually want to
+ // use a cache
+ if (_config->FindB("Acquire::http::No-Cache",false) == false)
{
if (Itm->IndexFile == true)
sprintf(Buf+strlen(Buf),"Cache-Control: max-age=%u\r\n",
- _config->FindI("Acquire::http::Max-Age",60*60*24));
+ _config->FindI("Acquire::http::Max-Age",0));
else
{
if (_config->FindB("Acquire::http::No-Store",false) == true)
}
}
}
+ // generate a no-cache header if needed
+ if (_config->FindB("Acquire::http::No-Cache",false) == true)
+ strcat(Buf,"Cache-Control: no-cache\r\nPragma: no-cache\r\n");
+
string Req = Buf;
if (stat(Itm->DestFile.c_str(),&SBuf) >= 0 && SBuf.st_size > 0)
{
// In this case we send an if-range query with a range header
- sprintf(Buf,"Range: bytes=%li-\r\nIf-Range: %s\r\n",SBuf.st_size - 1,
+ sprintf(Buf,"Range: bytes=%li-\r\nIf-Range: %s\r\n",(long)SBuf.st_size - 1,
TimeRFC1123(SBuf.st_mtime).c_str());
Req += Buf;
}
Req += string("Proxy-Authorization: Basic ") +
Base64Encode(Proxy.User + ":" + Proxy.Password) + "\r\n";
- Req += "User-Agent: Debian APT-HTTP/1.2\r\n\r\n";
-// cerr << Req << endl;
+ if (Uri.User.empty() == false || Uri.Password.empty() == false)
+ Req += string("Authorization: Basic ") +
+ Base64Encode(Uri.User + ":" + Uri.Password) + "\r\n";
+
+ Req += "User-Agent: Debian APT-HTTP/1.3\r\n\r\n";
+
+ if (Debug == true)
+ cerr << Req << endl;
Out.Read(Req);
}
bool HttpMethod::Go(bool ToFile,ServerState *Srv)
{
// Server has closed the connection
- if (Srv->ServerFd == -1 && Srv->In.WriteSpace() == false)
+ if (Srv->ServerFd == -1 && (Srv->In.WriteSpace() == false ||
+ ToFile == false))
return false;
- fd_set rfds,wfds,efds;
+ fd_set rfds,wfds;
FD_ZERO(&rfds);
FD_ZERO(&wfds);
- FD_ZERO(&efds);
- // Add the server
- if (Srv->Out.WriteSpace() == true && Srv->ServerFd != -1)
+ /* Add the server. We only send more requests if the connection will
+ be persisting */
+ if (Srv->Out.WriteSpace() == true && Srv->ServerFd != -1
+ && Srv->Persistent == true)
FD_SET(Srv->ServerFd,&wfds);
- if (Srv->In.ReadSpace() == true && Srv->ServerFd != -1)
+ if (Srv->In.ReadSpace() == true && Srv->ServerFd != -1)
FD_SET(Srv->ServerFd,&rfds);
// Add the file
// Add stdin
FD_SET(STDIN_FILENO,&rfds);
- // Error Set
- if (FileFD != -1)
- FD_SET(FileFD,&efds);
- if (Srv->ServerFd != -1)
- FD_SET(Srv->ServerFd,&efds);
-
// Figure out the max fd
int MaxFd = FileFD;
if (MaxFd < Srv->ServerFd)
MaxFd = Srv->ServerFd;
-
+
// Select
struct timeval tv;
tv.tv_sec = TimeOut;
tv.tv_usec = 0;
int Res = 0;
- if ((Res = select(MaxFd+1,&rfds,&wfds,&efds,&tv)) < 0)
- return _error->Errno("select","Select failed");
+ if ((Res = select(MaxFd+1,&rfds,&wfds,0,&tv)) < 0)
+ {
+ if (errno == EINTR)
+ return true;
+ return _error->Errno("select",_("Select failed"));
+ }
if (Res == 0)
{
- _error->Error("Connection timed out");
+ _error->Error(_("Connection timed out"));
return ServerDie(Srv);
}
- // Some kind of exception (error) on the sockets, die
- if ((FileFD != -1 && FD_ISSET(FileFD,&efds)) ||
- (Srv->ServerFd != -1 && FD_ISSET(Srv->ServerFd,&efds)))
- return _error->Error("Socket Exception");
-
// Handle server IO
if (Srv->ServerFd != -1 && FD_ISSET(Srv->ServerFd,&rfds))
{
if (FileFD != -1 && FD_ISSET(FileFD,&wfds))
{
if (Srv->In.Write(FileFD) == false)
- return _error->Errno("write","Error writing to output file");
+ return _error->Errno("write",_("Error writing to output file"));
}
// Handle commands from APT
if (FD_ISSET(STDIN_FILENO,&rfds))
{
- if (Run(true) != 0)
+ if (Run(true) != -1)
exit(100);
}
{
if (File != 0)
{
- SetNonBlock(File->Fd(),false);
+ // on GNU/kFreeBSD, apt dies on /dev/null because non-blocking
+ // can't be set
+ if (File->Name() != "/dev/null")
+ SetNonBlock(File->Fd(),false);
if (Srv->In.WriteSpace() == false)
return true;
while (Srv->In.WriteSpace() == true)
{
if (Srv->In.Write(File->Fd()) == false)
- return _error->Errno("write","Error writing to file");
+ return _error->Errno("write",_("Error writing to file"));
if (Srv->In.IsLimit() == true)
return true;
}
// Dump the buffer to the file
if (Srv->State == ServerState::Data)
{
- SetNonBlock(File->Fd(),false);
+ // on GNU/kFreeBSD, apt dies on /dev/null because non-blocking
+ // can't be set
+ if (File->Name() != "/dev/null")
+ SetNonBlock(File->Fd(),false);
while (Srv->In.WriteSpace() == true)
{
if (Srv->In.Write(File->Fd()) == false)
- return _error->Errno("write","Error writing to the file");
+ return _error->Errno("write",_("Error writing to the file"));
// Done
if (Srv->In.IsLimit() == true)
{
Srv->Close();
if (LErrno == 0)
- return _error->Error("Error reading from server Remote end closed connection");
+ return _error->Error(_("Error reading from server. Remote end closed connection"));
errno = LErrno;
- return _error->Errno("read","Error reading from server");
+ return _error->Errno("read",_("Error reading from server"));
}
else
{
failure */
if (Srv->Result < 200 || Srv->Result >= 300)
{
+ char err[255];
+ snprintf(err,sizeof(err)-1,"HttpError%i",Srv->Result);
+ SetFailReason(err);
_error->Error("%u %s",Srv->Result,Srv->Code);
if (Srv->HaveContent == true)
return 4;
// Set the start point
lseek(File->Fd(),0,SEEK_END);
- delete Srv->In.MD5;
- Srv->In.MD5 = new MD5Summation;
+ delete Srv->In.Hash;
+ Srv->In.Hash = new Hashes;
- // Fill the MD5 Hash if the file is non-empty (resume)
+ // Fill the Hash if the file is non-empty (resume)
if (Srv->StartPos > 0)
{
lseek(File->Fd(),0,SEEK_SET);
- if (Srv->In.MD5->AddFD(File->Fd(),Srv->StartPos) == false)
+ if (Srv->In.Hash->AddFD(File->Fd(),Srv->StartPos) == false)
{
- _error->Errno("read","Problem hashing file");
+ _error->Errno("read",_("Problem hashing file"));
return 5;
}
lseek(File->Fd(),0,SEEK_END);
void HttpMethod::SigTerm(int)
{
if (FailFd == -1)
- exit(100);
+ _exit(100);
close(FailFd);
// Timestamp
struct utimbuf UBuf;
- time(&UBuf.actime);
UBuf.actime = FailTime;
UBuf.modtime = FailTime;
utime(FailFile.c_str(),&UBuf);
- exit(100);
+ _exit(100);
}
/*}}}*/
// HttpMethod::Fetch - Fetch an item /*{{{*/
depth. */
bool HttpMethod::Fetch(FetchItem *)
{
- if (Server == 0)
+ if (Server == 0)
return true;
// Queue the requests
int Depth = -1;
bool Tail = false;
- for (FetchItem *I = Queue; I != 0 && Depth < (signed)PipelineDepth; I = I->Next, Depth++)
+ for (FetchItem *I = Queue; I != 0 && Depth < (signed)PipelineDepth;
+ I = I->Next, Depth++)
{
+ // If pipelining is disabled, we only queue 1 request
+ if (Server->Pipeline == false && Depth >= 0)
+ break;
+
// Make sure we stick with the same server
if (Server->Comp(I->Uri) == false)
break;
QueueBack = I->Next;
SendReq(I,Server->Out);
continue;
- }
+ }
}
return true;
TimeOut = _config->FindI("Acquire::http::Timeout",TimeOut);
PipelineDepth = _config->FindI("Acquire::http::Pipeline-Depth",
PipelineDepth);
+ Debug = _config->FindB("Debug::Acquire::http",false);
return true;
}
return 0;
}
- // Run messages
- if (Run(true) != 0)
+ /* Run messages, we can accept 0 (no message) if we didn't
+ do a WaitFd above.. Otherwise the FD is closed. */
+ int Result = Run(true);
+ if (Result != -1 && (Result != 0 || Queue == 0))
return 100;
if (Queue == 0)
delete Server;
Server = new ServerState(Queue->Uri,this);
}
-
+
+ /* If the server has explicitly said this is the last connection
+ then we pre-emptively shut down the pipeline and tear down
+ the connection. This will speed up HTTP/1.0 servers a tad
+ since we don't have to wait for the close sequence to
+ complete */
+ if (Server->Persistent == false)
+ Server->Close();
+
// Reset the pipeline
if (Server->ServerFd == -1)
QueueBack = Queue;
// The header data is bad
case 2:
{
- _error->Error("Bad header Data");
+ _error->Error(_("Bad header data"));
Fail(true);
+ RotateDNS();
continue;
}
FailCounter++;
_error->Discard();
Server->Close();
-
+ Server->Pipeline = false;
+
if (FailCounter >= 2)
{
- Fail("Connection timed out",true);
+ Fail(_("Connection failed"),true);
FailCounter = 0;
}
+ RotateDNS();
continue;
}
};
// Run the data
bool Result = Server->RunData();
+ /* If the server is sending back sizeless responses then fill in
+ the size now */
+ if (Res.Size == 0)
+ Res.Size = File->Size();
+
// Close the file, destroy the FD object and timestamp it
FailFd = -1;
delete File;
// Send status to APT
if (Result == true)
{
- Res.MD5Sum = Server->In.MD5->Result();
+ Res.TakeHashes(*Server->In.Hash);
URIDone(Res);
}
else
Fail(true);
-
+
break;
}
// Hard internal error, kill the connection and fail
case 5:
{
+ delete File;
+ File = 0;
+
Fail();
+ RotateDNS();
Server->Close();
break;
}
}
default:
- Fail("Internal error");
+ Fail(_("Internal error"));
break;
}
}
/*}}}*/
-int main()
-{
- HttpMethod Mth;
-
- return Mth.Loop();
-}
+
+
projects / apt.git / blobdiff