Data sending method and apparatus, and method and system for establishing P2P connection

A method of establishing a peer to peer (P2P) connection, comprising:

• sending, by a first terminal device, n2 second access request data packets at a second preset time interval t2 by using one file descriptor, wherein the first terminal device is associated with port-restricted network address translation (NAT), and wherein the n2 second access request data packets comprises a same destination IP address and different destination ports, wherein a second terminal device that is associated with symmetric NAT and that corresponds to the destination IP address comprised in the n2 second access request data packets, wherein the second terminal device is configured to performs operations comprising:
• S1:
• establishing a queue for accommodating m file descriptors for n1 first access request data packets to be sent from the second terminal device, wherein 2≤m<n1,
• S2:
• creating an ith file descriptor in the queue, sending an ith first access request data packet by using the ith file descriptor, and monitoring a source port recorded by the ith file descriptor, wherein the ith file descriptor has a same source port as the ith first access request data packet, and 1≤i≤n1,
• S3:
• at every first preset time interval t1, enabling i to automatically increase by 1, continuing to perform operation S2, and setting a preset monitoring time T for each source port, wherein each file descriptor records a different source port, and T=t1*m, and
• S4:
• ending monitoring of an (i-m)th source port and destroying a corresponding file descriptor while creating an ith file descriptor in the queue when m*j<i≤m*(j+1);
• within a t2*n2+t1*n1 monitoring time period of a source port of the first terminal device, in response to detecting that the source port of the first terminal device receives a first access request data packet from the second terminal device by the port-restricted NAT, obtaining, by the first terminal device, address information in the first access request data packet, and sending a response data packet based on the obtained address information;
• and
• in response to detecting that a first port of the second terminal device receives the response data packet, stopping, by the symmetric NAT, monitoring other source ports, wherein the first port corresponds to the obtained address information.

A system for establishing a peer to peer (P2P) connection, comprising port-restricted network address translation (NAT), a first terminal device associated with the port-restricted NAT, symmetric NAT, and a second terminal device associated with the symmetric NAT,

• wherein the first terminal device is configured to send n2 second access request data packets at a second preset time interval t2 by using one file descriptor, wherein the n2 second access request data packets comprise a same destination IP address and different destination ports;
• wherein the second terminal device corresponds to the destination IP address comprised in the n2 second access request data packets, and the second terminal device is configured to perform operations comprising:
• S1:
• establishing a queue for accommodating m file descriptors for n1 first access request data packets to be sent from the second terminal device, wherein 2≤m<n1,
• S2:
• creating an ith file descriptor in the queue, sending an ith first access request data packet by using the ith file descriptor, and monitoring a source port recorded by the ith file descriptor, wherein the ith file descriptor has a same source port as the ith first access request data packet, and 1≤i≤n1,
• S3:
• at every first preset time interval t1, enabling i to automatically increase by 1, continuing to perform operation S2, and setting a preset monitoring time T for each source port, wherein each file descriptor records a different source port, and T=t1*m, and
• S4:
• ending monitoring of an (i-m)th source port and destroying a corresponding file descriptor for creating the ith file descriptor in the queue when m*j<i≤m*(j+1);
• wherein the first terminal device is further configured to:
• within a t2*n2+t1*n1 monitoring time period of a source port of the first terminal device, in response to detecting that the source port of the first terminal device receives a first access request data packet from the second terminal device by the port-restricted NAT, obtain address information in the first access request data packet, and send a response data packet based on the obtained address information;
• and
• wherein the symmetric NAT is configured to:
• when detecting that a first port of the second terminal device receives the response data packet, stop monitoring other source ports, wherein the first port of the second terminal device corresponds to the obtained address information.

A computing device, comprising a memory, a processor, and computer instructions that are stored in the memory and executable by the processor, wherein the computer instructions upon execution by the processor cause the processor to perform operations comprising:

• establishing a queue for accommodating m file descriptors for generating n1 first access request data packets to be sent from the computing device, wherein 2≤m<n1, wherein the computing device is associated with symmetric network address translation (NAT);
• creating an ith file descriptor in the queue, generating and sending an ith first access request data packet by using the ith file descriptor, and monitoring a source port recorded by the ith file descriptor, wherein the ith file descriptor corresponds to a same source port as the ith first access request data packet, and 1≤i≤n1;
• at every first preset time interval t1, enabling i to automatically increase by 1, continuing to perform operations of creating an (i+1)th file descriptor in the queue, generating and sending an (i+1)th first access request data packet by using the (i+1)th file descriptor, and monitoring a source port recorded by the (i+1)th file descriptor, and setting a preset monitoring time T for each source port, wherein each file descriptor records a different source port, and T=t1*m,
• ending monitoring of an (i-m)th source port and destroying a corresponding file descriptor while creating an ith file descriptor in the queue when m*j<i≤m*(j+1), wherein j≥1,
• stopping monitoring other source ports in response to detecting that a first port of the computing device receives a response data packet, and wherein the first port is any source port in a monitored state.