Many interfaces to the linux kernel are not well documented. Or even if they seem well documented, they can be pretty complex and that can make it hard to understanding what the functional or, often even harder, nonfunctional properties of the interface are. For this reason, my advice to anyone wanting a solid understanding of … Read more
TCP/IP is a protocol stack for communication, a socket is an endpoint in a (bidirectional) communication. A socket need not be TCP based, but it is quite often the case. The term socket is also often used to refer to the API provided by the operating system that allows you to make a connection over … Read more
The close call only marks the TCP socket closed. It is not usable by process anymore. But kernel may still hold some resources for a period (TIME_WAIT, 2MLS etc stuff). Setting of SO_REUSEADDR should remove binding problems. So be sure that value of true is really non-zero when calling setsockopt (overflow bug may overwrite it): … Read more
Based on suggestion by Saint_pl: I found probably better solution – similar to SharpPcap. It’s Pcap.Net – .NET wrapper for WinPcap. Now I can modify my packets whatever I want. I have some resources for you that maybe helpful. I don’t try that solutions in Windows 7 but maybe it contains some good info to … Read more
The UDP checksum is performed over the entire payload, and the other fields in the header, and some fields from the IP header. A pseudo-header is constructed from the IP header in order to perform the calculation (which is done over this pseudo-header, the UDP header and the payload). The reason the pseudo-header is included … Read more
Overview SOAP is a messaging protocol and in a nutshell is just another XML language. Its purpose is the data exchange over networks. Its concern is the encapsulation of these data and the rules for transmitting and receiving them. HTTP is an application protocol and SOAP messages are placed as the HTTP payload. Although there … Read more
Let’s write both in binary: 130.45.34.36 = 10000010.00101101.00100010.00100100 255.255.240.0 = 11111111.11111111.11110000.00000000 A bitwise AND between the two would give us the network address: 10000010.00101101.00100010.00100100 (ip address) AND 11111111.11111111.11110000.00000000 (subnet mask) = 10000010.00101101.00100000.00000000 = 130.45.32.0 (the resulting network address) A bitwise OR between the network address and the inverted subnet mask would give us the broadcast … Read more
The best way to go is to use getaddrinfo(). Pseudo code: struct addrinfo *restrict hints = { .ai_family = AF_UNSPEC, .ai_socktype = SOCK_STREAM }; struct addrinfo * res, r; if (0 == getaddrinfo(“foo.bar.baz”, “http”, &hints, &res)) { for (r=res; r; r=r->ai_next) { sock = socket(r->ai_family, r->ai_socktype, r->ai_protocol); connect(sock, r->ai_addr, r->ai_addrlen); if error: continue break } … Read more