Method and apparatus for limiting traffic rate to an origin server

A proxy server for limiting a rate at which traffic is received at an origin server, the proxy server comprising:

• a non-transitory computer readable storage medium to store instructions;
• and
• a processor coupled with the non-transitory computer readable storage medium to process the stored instructions to:
• receive, from a client device, a first request for a resource at an origin server;
• transmit, to the client device, a first response that includes a refresh instruction, a first refresh time, and a first cryptographic token that is not valid until a first predetermined time is reached, and wherein the refresh instruction is to cause the client device to request the resource after the first refresh time has elapsed;
• increment a value of a first counter;
• receive as a result of the refresh instruction a second request for the resource from the client device, wherein the second request includes the first cryptographic token;
• determine that the first cryptographic token is not valid;
• and
• responsive to determining that the first cryptographic token is not valid, perform:
• (a) responsive to determining that a value of a second counter is strictly smaller than a maximum number of client devices that can access the origin server during a predetermined interval of time, transmit a second response including the refresh instruction, a second refresh time, and a second cryptographic token that is not valid until a second predetermined time is reached, wherein the second predetermined time occurs earlier than the first predetermined time, increment the value of the second counter, and decrement the value of the first counter,
• (b) responsive to determining that the value of the second counter is not strictly smaller than the maximum number of client devices that can access the origin server during a predetermined interval of time, transmit a third response that includes the refresh instruction, the first refresh time, and the first cryptographic token,
• (c) receive a third request for the resource from the client device, wherein the third request includes at least one of the first cryptographic token and the second cryptographic token,
• (d) repeat (a), (b) and (c) until receiving a request from the client device that includes at least one of the first cryptographic token and the second cryptographic token that is valid, and
• (e) responsive to determining that at least one of the first cryptographic token and the second cryptographic token is valid, fulfil the third request.

A non-transitory computer readable storage medium that provide instructions, which when executed by a processor of a proxy server, cause said processor to perform operations comprising:

• receiving, from a client device, a first request for a resource at an origin server;
• transmitting, to the client device, a first response that includes a refresh instruction, a first refresh time, and a first cryptographic token that is not valid until a first predetermined time is reached, and wherein the refresh instruction is to cause the client device to request the resource after the first refresh time has elapsed;
• incrementing a value of a first counter;
• receiving as a result of the refresh instruction a second request for the resource from the client device, wherein the second request includes the first cryptographic token;
• determining that the first cryptographic token is not valid;
• and
• responsive to determining that the first cryptographic token is not valid, performing:
• (f) responsive to determining that a value of a second counter is strictly smaller than a maximum number of client devices that can access the origin server during a predetermined interval of time, transmitting a second response including the refresh instruction, a second refresh time, and a second cryptographic token that is not valid until a second predetermined time is reached, wherein the second predetermined time occurs earlier than the first predetermined time, incrementing the value of the second counter, and decrementing the value of the first counter,
• (g) responsive to determining that the value of the second counter is not strictly smaller than the maximum number of client devices that can access the origin server during a predetermined interval of time, transmitting a third response that includes the refresh instruction, the first refresh time, and the first cryptographic token,
• (h) receiving a third request for the resource from the client device, wherein the third request includes at least one of the first cryptographic token and the second cryptographic token,
• (i) repeating (a), (b) and (c) until receiving a request from the client device that includes at least one of the first cryptographic token and the second cryptographic token that is valid, and
• (j) responsive to determining that at least one of the first cryptographic token and the second cryptographic token is valid, fulfilling the third request.