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Added length type wrapper in sockaddr_any for convenience. #1492

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merged 1 commit into from
Sep 1, 2020
Merged

Added length type wrapper in sockaddr_any for convenience. #1492

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4 changes: 1 addition & 3 deletions apps/srt-tunnel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -675,13 +675,11 @@ unique_ptr<Medium> SrtMedium::Accept()
unique_ptr<Medium> TcpMedium::Accept()
{
sockaddr_any sa;
socklen_t salen = sizeof sa;
int s = ::accept(m_socket, (sa.get()), (&salen));
int s = ::accept(m_socket, (sa.get()), (&sa.syslen()));
if (s == -1)
{
Error(errno, "accept");
}
sa.len = salen;

// Configure 1s timeout
timeval timeout_1s { 1, 0 };
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23 changes: 23 additions & 0 deletions srtcore/netinet_any.h
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Expand Up @@ -58,6 +58,29 @@ struct sockaddr_any
// back here from the value of `syslen_t`.
len_t len;

struct SysLenWrapper
{
syslen_t syslen;
len_t& backwriter;
syslen_t* operator&() { return &syslen; }

SysLenWrapper(len_t& source): syslen(source), backwriter(source)
{
}

~SysLenWrapper()
{
backwriter = syslen;
}
};

// Usage:
// ::accept(lsn_sock, sa.get(), &sa.syslen());
SysLenWrapper syslen()
{
return SysLenWrapper(len);
}

static size_t storage_size()
{
typedef union
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4 changes: 1 addition & 3 deletions testing/testmedia.cpp
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Expand Up @@ -2517,16 +2517,14 @@ class UdpSource: public virtual Source, public virtual UdpCommon
{
bytevector data(chunk);
sockaddr_any sa(sadr.family());
socklen_t si = sa.size();
int64_t srctime = 0;
int stat = recvfrom(m_sock, data.data(), (int) chunk, 0, sa.get(), &si);
int stat = recvfrom(m_sock, data.data(), (int) chunk, 0, sa.get(), &sa.syslen());
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Dereferencing a temporal object SysLenWrapper::syslen.... 🤔

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Allowed, as long as you don't access it after it is deleted. We know it is not deleted until the current instruction finishes execution, so it won't happen before returning from the function. It actually does the same as the "temporary variable" solution used previously, just the trick is hidden inside.

if (transmit_use_sourcetime)
{
srctime = srt_time_now();
}
if (stat == -1)
Error(SysError(), "UDP Read/recvfrom");
sa.len = si;

if (stat < 1)
{
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