[Asio] Cannot set port number on endpoint
Hi, I'm new to Boost and am trying to write a command line networking tool. I am currently working in Windows XP SP2 using MS Visual Studio 2005. I use the default compiler. I have read a few tutorials and examples on using Asio, and thus wrote my app using that information, as well as information from the reference library. Currently the problem that I have is that I cannot set the port used by the endpoint to the value I want - 10540 - it is always set to 11035. I'm not sure why this is, I cant find the number 11035 anywhere in the code or documentation so I am not sure where it comes from. I have tried to instantiate a new endpoint using the IPv4 address as a string and the port number as a short, and have also tried to construct a query that specifies the protocol, host name, service name (port number in this case) and the numeric_service flag. In either case, when I debug, the port of the endpoint is always 11035, no matter what I set it to. I am able to connect to the endpoint, but not able to write data to it. I get a "File handle supplied is not valid error message". I presume the most likely reason for this is that the port 11035 is not open. The machine that I am trying to connect to is running Red Hat EL4 Update 4. I would appreciate any help in this matter. Thank you, Jonathan.
Jonathan Locke wrote:
I'm new to Boost and am trying to write a command line networking tool. I am currently working in Windows XP SP2 using MS Visual Studio 2005. I use the default compiler. I have read a few tutorials and examples on using Asio, and thus wrote my app using that information, as well as information from the reference library. Currently the problem that I have is that I cannot set the port used by the endpoint to the value I want - 10540 - it is always set to 11035. I'm not sure why this is, I cant find the number 11035 anywhere in the code or documentation so I am not sure where it comes from. I have tried to instantiate a new endpoint using the IPv4 address as a string and the port number as a short, and have also tried to construct a query that specifies the protocol, host name, service name (port number in this case) and the numeric_service flag.
In either case, when I debug, the port of the endpoint is always 11035, no matter what I set it to. I am able to connect to the endpoint, but not able to write data to it. I get a "File handle supplied is not valid error message". I presume the most likely reason for this is that the port 11035 is not open.
Do you mean 11035 or 11305? I ask this because, when I swap the bytes of 10540, I get 11305. I'm not familiar with ASIO, but I know that in network communication, integers are sent in "network byte order," which is most significant byte first, but Intel processors store integers least significant byte first. Hence the need to swap them. I'm surprised ASIO isn't swapping the bytes for you. Perhaps one of our resident ASIO gurus could provide some insight on this. Of course, if you really meant 11035, then kindly disregard this message.
On Jun 19, 2008, at 8:22 AM, Andrew Holden wrote:
In either case, when I debug, the port of the endpoint is always 11035, no matter what I set it to. I am able to connect to the endpoint, but not able to write data to it. I get a "File handle supplied is not valid error message". I presume the most likely reason for this is that the port 11035 is not open.
Do you mean 11035 or 11305? I ask this because, when I swap the bytes of 10540, I get 11305.
I'm not familiar with ASIO, but I know that in network communication, integers are sent in "network byte order," which is most significant byte first, but Intel processors store integers least significant byte first. Hence the need to swap them.
I had that thought at first too, but on rereading his original message realized he did say "no matter what I set it to," and realized I must be thinking something way too simple to actually be the problem. :-) Good mention, though! - Chris
I'm not familiar with ASIO, but I know that in network communication, integers are sent in "network byte order," which is most significant byte first, but Intel processors store integers least significant byte first.
I had that thought at first too, but on rereading his original message realized he did say "no matter what I set it to," and realized I must be thinking something way too simple to actually be the problem. :-)
Besides, ASIO takes care for the correct interpretation of the addres (including the right byte-order), you can set the IP&port in a "human-readable" form. According to the description of the OP, it seems that 11035 is the local port that the application opens for the outgoing connection - this explains why it's always the same.
participants (4)
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Andrew Holden -
Chris Ross -
Igor R -
Jonathan Locke