If a HTTP server backlog becomes very large (>1 GB), kill the connection to avoid...

diff --git a/shared/httpd.cpp b/shared/httpd.cpp
index 5442e7f123f7533b9740fc244241acd9123b1703..f447f54876f33b5bbeb453d4cf994cbf9b39c853 100644 (file)
--- a/shared/httpd.cpp
+++ b/shared/httpd.cpp
@@ -182,7 +182,7 @@ ssize_t HTTPD::Stream::reader_callback(uint64_t pos, char *buf, size_t max)
        unique_lock<mutex> lock(buffer_mutex);
        has_buffered_data.wait(lock, [this] { return should_quit || !buffered_data.empty(); });
        if (should_quit) {
-               return 0;
+               return -1;
        }
 
        ssize_t ret = 0;
@@ -196,6 +196,7 @@ ssize_t HTTPD::Stream::reader_callback(uint64_t pos, char *buf, size_t max)
                        buf += len;
                        ret += len;
                        max -= len;
+                       buffered_data_bytes -= s.size();
                        buffered_data.pop_front();
                        used_of_buffered_data = 0;
                } else {
@@ -213,7 +214,7 @@ ssize_t HTTPD::Stream::reader_callback(uint64_t pos, char *buf, size_t max)
 
 void HTTPD::Stream::add_data(const char *buf, size_t buf_size, HTTPD::Stream::DataType data_type, int64_t time, AVRational timebase)
 {
-       if (buf_size == 0) {
+       if (buf_size == 0 || should_quit) {
                return;
        }
        if (data_type == DATA_TYPE_KEYFRAME) {
@@ -225,6 +226,17 @@ void HTTPD::Stream::add_data(const char *buf, size_t buf_size, HTTPD::Stream::Da
 
        lock_guard<mutex> lock(buffer_mutex);
 
+       if (buffered_data_bytes + buf_size > (1ULL << 30)) {
+               // More than 1GB of backlog; the client obviously isn't keeping up,
+               // so kill it instead of going out of memory. Note that this
+               // won't kill the client immediately, but will cause the next callback
+               // to kill the client.
+               should_quit = true;
+               buffered_data.clear();
+               has_buffered_data.notify_all();
+               return;
+       }
+
        if (framing == FRAMING_METACUBE) {
                int flags = 0;
                if (data_type == DATA_TYPE_HEADER) {
@@ -249,6 +261,7 @@ void HTTPD::Stream::add_data(const char *buf, size_t buf_size, HTTPD::Stream::Da
                        hdr.csum = htons(metacube2_compute_crc(&hdr));
                        buffered_data.emplace_back((char *)&hdr, sizeof(hdr));
                        buffered_data.emplace_back((char *)&packet, sizeof(packet));
+                       buffered_data_bytes += sizeof(hdr) + sizeof(packet);
                }
 
                metacube2_block_header hdr;
@@ -257,8 +270,10 @@ void HTTPD::Stream::add_data(const char *buf, size_t buf_size, HTTPD::Stream::Da
                hdr.flags = htons(flags);
                hdr.csum = htons(metacube2_compute_crc(&hdr));
                buffered_data.emplace_back((char *)&hdr, sizeof(hdr));
+               buffered_data_bytes += sizeof(hdr);
        }
        buffered_data.emplace_back(buf, buf_size);
+       buffered_data_bytes += buf_size;
 
        // Send a Metacube2 timestamp every keyframe.
        if (framing == FRAMING_METACUBE && data_type == DATA_TYPE_KEYFRAME) {
@@ -277,6 +292,7 @@ void HTTPD::Stream::add_data(const char *buf, size_t buf_size, HTTPD::Stream::Da
                hdr.csum = htons(metacube2_compute_crc(&hdr));
                buffered_data.emplace_back((char *)&hdr, sizeof(hdr));
                buffered_data.emplace_back((char *)&packet, sizeof(packet));
+               buffered_data_bytes += sizeof(hdr) + sizeof(packet);
        }
 
        has_buffered_data.notify_all();

diff --git a/shared/httpd.h b/shared/httpd.h
index 2a628594c91beb2d556c8df3459ac526287f7d50..6c9a254307aee03f5b15b347e32c7a521a863b9a 100644 (file)
--- a/shared/httpd.h
+++ b/shared/httpd.h
@@ -106,7 +106,8 @@ private:
                bool should_quit = false;  // Under <buffer_mutex>.
                std::condition_variable has_buffered_data;
                std::deque<std::string> buffered_data;  // Protected by <buffer_mutex>.
-               size_t used_of_buffered_data = 0;  // How many bytes of the first element of <buffered_data> that is already used. Protected by <mutex>.
+               size_t used_of_buffered_data = 0;  // How many bytes of the first element of <buffered_data> that is already used. Protected by <buffer_mutex>.
+               size_t buffered_data_bytes = 0;  // The sum of all size() in buffered_data. Protected by <buffer_mutex>.
                size_t seen_keyframe = false;
                StreamType stream_type;
        };