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avrl ☘ @avrldotdev

Backend Dev | I write on System Design, AI & Open Source | Medium: avrl.medium.com

Joined November 2024
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avrl ☘
@avrldotdev
May 13
x.com/i/article/205245122262…

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Step-1: Learn Go Step-2: Master structs, interfaces & pointers Step-3: Learn goroutines & channels Step-4: Build an HTTP server with std-lib Step-5: Read the Go runtime & standard library source. Embrace humility Step-6: Build a production-grade backend (REST/gRPC, DB, caching, etc) Step-7: Make it load-bearing Step-8: Learn profiling & optimization (pprof, trace, benchmarks) Step-9: deploy with Docker (& K8s) Step-10: Ship it
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avrl ☘ retweeted
avrl ☘
@avrldotdev
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Day 10 of Implementing Raft in Go. Almost done with log replication. Any new log entry first applies the leader log, sent to all followers & if majority of them say they applied it too, its committed to the leader's state machine (DB/Store) Its a lot of back & forth b/w nodes.
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avrl ☘ retweeted
avrl ☘
@avrldotdev
22h
It's over for me, back to being a caveman for the rest of the month!
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avrl ☘
@avrldotdev
Jun 13
Assembly is still a high level language.
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avrl ☘ retweeted
avrl ☘
@avrldotdev
Jun 12
this c code looks harmless on first glance but mimics one the most famous & dangerous bugs in OpenSSL. It's not your typical buffer overflow exploit but much worse in reality. can you tell why is it so?
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> typedef struct { uint16_t length; char data[16]; } Message; int main() { Message msg; // User-controlled input printf("Claimed length: "); scanf("%hu", &msg.length); printf("Message: "); scanf("s", msg.data); // Allocate buffer based on claimed length char *copy = malloc(msg.length); // Vulnerability: // msg.data may contain only a few bytes, // but msg.length can be arbitrarily large. memcpy(copy, msg.data, msg.length); printf("\nCopied bytes:\n"); fwrite(copy, 1, msg.length, stdout); printf("\n"); free(copy); return 0; }

ALT #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> typedef struct { uint16_t length; char data[16]; } Message; int main() { Message msg; // User-controlled input printf("Claimed length: "); scanf("%hu", &msg.length); printf("Message: "); scanf("s", msg.data); // Allocate buffer based on claimed length char *copy = malloc(msg.length); // Vulnerability: // msg.data may contain only a few bytes, // but msg.length can be arbitrarily large. memcpy(copy, msg.data, msg.length); printf("\nCopied bytes:\n"); fwrite(copy, 1, msg.length, stdout); printf("\n"); free(copy); return 0; }

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this c code looks harmless on first glance but mimics one the most famous & dangerous bugs in OpenSSL. It's not your typical buffer overflow exploit but much worse in reality. can you tell why is it so?
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> typedef struct { uint16_t length; char data[16]; } Message; int main() { Message msg; // User-controlled input printf("Claimed length: "); scanf("%hu", &msg.length); printf("Message: "); scanf("s", msg.data); // Allocate buffer based on claimed length char *copy = malloc(msg.length); // Vulnerability: // msg.data may contain only a few bytes, // but msg.length can be arbitrarily large. memcpy(copy, msg.data, msg.length); printf("\nCopied bytes:\n"); fwrite(copy, 1, msg.length, stdout); printf("\n"); free(copy); return 0; }

ALT #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> typedef struct { uint16_t length; char data[16]; } Message; int main() { Message msg; // User-controlled input printf("Claimed length: "); scanf("%hu", &msg.length); printf("Message: "); scanf("s", msg.data); // Allocate buffer based on claimed length char *copy = malloc(msg.length); // Vulnerability: // msg.data may contain only a few bytes, // but msg.length can be arbitrarily large. memcpy(copy, msg.data, msg.length); printf("\nCopied bytes:\n"); fwrite(copy, 1, msg.length, stdout); printf("\n"); free(copy); return 0; }

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this was the real snippet where the issue was in OpenSSL. Millions of devices were compromised at once & it was a wakeup call to fund & maintain open-source properly.
/* Read type and payload length first */ hbtype = *p ; n2s(p, payload); pl = p; /* Allocate memory for the response */ buffer = OPENSSL_malloc(1 2 payload padding); bp = buffer; /* Enter response type */ *bp = TLS1_HB_RESPONSE; /* Copy payload length */ s2n(payload, bp); /* Copy payload */ memcpy(bp, pl, payload); /* Random padding */ RAND_pseudo_bytes(bp payload, padding);

ALT /* Read type and payload length first */ hbtype = *p ; n2s(p, payload); pl = p; /* Allocate memory for the response */ buffer = OPENSSL_malloc(1 2 payload padding); bp = buffer; /* Enter response type */ *bp = TLS1_HB_RESPONSE; /* Copy payload length */ s2n(payload, bp); /* Copy payload */ memcpy(bp, pl, payload); /* Random padding */ RAND_pseudo_bytes(bp payload, padding);

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I interviewed for a tech firm last year. Everything was going fine, cleared the OA, one DSA & two system design rounds. Before my final round, the recruiter tells me the HM wants someone from IITs/NITs. This type of stuff should get people fired!
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Anyone else had such weird interview experiences? Would love to hear in the comments or quotes
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avrl ☘ retweeted
avrl ☘
@avrldotdev
Jun 12
I interviewed for a tech firm last year. Everything was going fine, cleared the OA, one DSA & two system design rounds. Before my final round, the recruiter tells me the HM wants someone from IITs/NITs. This type of stuff should get people fired!
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avrl ☘ retweeted
avrl ☘
@avrldotdev
Jun 11
Day 9 of learning/implementing Raft in Go Log replication is underway, its pretty complicated with the states you need to maintain. There are 2 states, persisted & volatile, former holds the log & its metadata & latter stores the leader's info about each of the followers log states which gets reinit on new election. Next up: replace in-memory to db store.
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Day 9 of learning/implementing Raft in Go Log replication is underway, its pretty complicated with the states you need to maintain. There are 2 states, persisted & volatile, former holds the log & its metadata & latter stores the leader's info about each of the followers log states which gets reinit on new election. Next up: replace in-memory to db store.
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paper for anyone to refer:raft.github.io/raft.pdf
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avrl ☘ retweeted
avrl ☘
@avrldotdev
Jun 11
I have a workaholic friend who really did long hours to build some leverage in his first job. In his performance review, manager told him he'll be up for a promotion if he keeps it up. So he worked even longer hours & harder. He was laid off a month later.
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Its so sad that PrimeAgen won't see this prediction of mine which matched his 2nd prediction on his latest yt video. (He blocked me long back for spamming) Can you guys tag/send this to him?
avrl ☘
@avrldotdev
Jun 4
Its not far off in the future when companies will mention your annual token budget in your offer letters & devs will negotiate based on that too.
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Video timestamp: youtu.be/m-bT5v5Tm7w?t=4m49s

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